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Sample records for charge-free etching process

  1. Laser-driven fusion etching process

    DOEpatents

    Ashby, C.I.H.; Brannon, P.J.; Gerardo, J.B.

    1987-08-25

    The surfaces of solids are etched by a radiation-driven chemical reaction. The process involves exposing a substrate coated with a layer of a reactant material on its surface to radiation, e.g., a laser, to induce localized melting of the substrate which results in the occurrence of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic substrates, e.g., LiNbO/sub 3/, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  2. Laser-driven fusion etching process

    DOEpatents

    Ashby, Carol I. H.; Brannon, Paul J.; Gerardo, James B.

    1989-01-01

    The surfaces of solid ionic substrates are etched by a radiation-driven chemical reaction. The process involves exposing an ionic substrate coated with a layer of a reactant material on its surface to radiation, e.g. a laser, to induce localized melting of the substrate which results in the occurrance of a fusion reaction between the substrate and coating material. The resultant reaction product and excess reactant salt are then removed from the surface of the substrate with a solvent which is relatively inert towards the substrate. The laser-driven chemical etching process is especially suitable for etching ionic salt substrates, e.g., a solid inorganic salt such as LiNbO.sub.3, such as used in electro-optical/acousto-optic devices. It is also suitable for applications wherein the etching process is required to produce an etched ionic substrate having a smooth surface morphology or when a very rapid etching rate is desired.

  3. Graphene nanoribbons: Relevance of etching process

    SciTech Connect

    Simonet, P. Bischoff, D.; Moser, A.; Ihn, T.; Ensslin, K.

    2015-05-14

    Most graphene nanoribbons in the experimental literature are patterned using plasma etching. Various etching processes induce different types of defects and do not necessarily result in the same electronic and structural ribbon properties. This study focuses on two frequently used etching techniques, namely, O{sub 2} plasma ashing and O{sub 2 }+ Ar reactive ion etching (RIE). O{sub 2} plasma ashing represents an alternative to RIE physical etching for sensitive substrates, as it is a more gentle chemical process. We find that plasma ashing creates defective graphene in the exposed trenches, resulting in instabilities in the ribbon transport. These are probably caused by more or larger localized states at the edges of the ashed device compared to the RIE defined device.

  4. Process for etching mixed metal oxides

    DOEpatents

    Ashby, C.I.H.; Ginley, D.S.

    1994-10-18

    An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

  5. Process for etching mixed metal oxides

    DOEpatents

    Ashby, Carol I. H.; Ginley, David S.

    1994-01-01

    An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

  6. Environmentally benign semiconductor processing for dielectric etch

    NASA Astrophysics Data System (ADS)

    Liao, Marci Yi-Ting

    Semiconductor processing requires intensive usage of chemicals, electricity, and water. Such intensive resource usage leaves a large impact on the environment. For instance, in Silicon Valley, the semiconductor industry is responsible for 80% of the hazardous waste sites contaminated enough to require government assistance. Research on environmentally benign semiconductor processing is needed to reduce the environmental impact of the semiconductor industry. The focus of this dissertation is on the environmental impact of one aspect of semiconductor processing: patterning of dielectric materials. Plasma etching of silicon dioxide emits perfluorocarbons (PFCs) gases, like C2F6 and CF4, into the atmosphere. These gases are super global warming/greenhouse gases because of their extremely long atmospheric lifetimes and excellent infrared absorption properties. We developed the first inductively coupled plasma (ICP) abatement device for destroying PFCs downstream of a plasma etcher. Destruction efficiencies of 99% and 94% can be obtained for the above mentioned PFCs, by using O 2 as an additive gas. Our results have lead to extensive modeling in academia as well as commercialization of the ICP abatement system. Dielectric patterning of hi-k materials for future device technology brings different environment challenges. The uncertainty of the hi-k material selection and the patterning method need to be addressed. We have evaluated the environmental impact of three different dielectric patterning methods (plasma etch, wet etch and chemical-mechanical polishing), as well as, the transistor device performances associated with the patterning methods. Plasma etching was found to be the most environmentally benign patterning method, which also gives the best device performance. However, the environmental concern for plasma etching is the possibility of cross-contamination from low volatility etch by-products. Therefore, mass transfer in a plasma etcher for a promising hi

  7. Aspect ratio dependent etching lag reduction in deep silicon etch processes

    SciTech Connect

    Lai, S.L.; Johnson, D.; Westerman, R.

    2006-07-15

    Microelectromechanical system (MEMS) device fabrication often involves three dimensional structures with high aspect ratios. Moreover, MEMS designs require structures with different dimensions and aspect ratios to coexist on a single microchip. There is a well-documented aspect ratio dependent etching (ARDE) effect in deep silicon etching processes. For features with different dimensions etched simultaneously, the ARDE effect causes bigger features to be etched at faster rates. In practice, ARDE effect has many undesired complications to MEMS device fabrication. This article presents a physical model to describe the time division multiplex (TDM) plasma etch processes and thereafter the experimental results on ARDE lag reduction. The model breaks individual plasma etch cycles in the TDM plasma etch processes into polymer deposition, polymer removal, and spontaneous silicon etching stages. With the insights gained from the model and control over the passivation and etch steps, it has been demonstrated that ARDE lag can be controlled effectively. Experiments have shown that a normal ARDE lag can be changed to an inverse ARDE lag. Under optimized conditions, the ARDE lag is reduced to below 2%-3% for trenches with widths ranging from 2.5 to 100 {mu}m, while maintaining good etch profile in trenches with different dimensions. Such results are achieved at etch rates exceeding 2 {mu}m/min.

  8. Dry etched SiO2 Mask for HgCdTe Etching Process

    NASA Astrophysics Data System (ADS)

    Chen, Y. Y.; Ye, Z. H.; Sun, C. H.; Deng, L. G.; Zhang, S.; Xing, W.; Hu, X. N.; Ding, R. J.; He, L.

    2016-09-01

    A highly anisotropic etching process with low etch-induced damage is indispensable for advanced HgCdTe (MCT) infrared focal plane array (IRFPA) detectors. The inductively coupled plasma (ICP) enhanced reactive ion etching technique has been widely adopted in manufacturing HgCdTe IRFPA devices. An accurately patterned mask with sharp edges is decisive to accomplish pattern duplication. It has been reported by our group that the SiO2 mask functions well in etching HgCdTe with high selectivity. However, the wet process in defining the SiO2 mask is limited by ambiguous edges and nonuniform patterns. In this report, we patterned SiO2 with a mature ICP etching technique, prior to which a thin ZnS film was deposited by thermal evaporation. The SiO2 film etching can be terminated at the auto-stopping point of the ZnS layer thanks to the high selectivity of SiO2/ZnS in SF6 based etchant. Consequently, MCT etching was directly performed without any other treatment. This mask showed acceptable profile due to the maturity of the SiO2 etching process. The well-defined SiO2 pattern and the etched smooth surfaces were investigated with scanning electron microscopy and atomic force microscope. This new mask process could transfer the patterns exactly with very small etch-bias. A cavity with aspect-ratio (AR) of 1.2 and root mean square roughness of 1.77 nm was achieved first, slightly higher AR of 1.67 was also get with better mask profile. This masking process ensures good uniformity and surely benefits the delineation of shrinking pixels with its high resolution.

  9. Automated process control for plasma etching

    NASA Astrophysics Data System (ADS)

    McGeown, Margaret; Arshak, Khalil I.; Murphy, Eamonn

    1992-06-01

    This paper discusses the development and implementation of a rule-based system which assists in providing automated process control for plasma etching. The heart of the system is to establish a correspondence between a particular data pattern -- sensor or data signals -- and one or more modes of failure, i.e., a data-driven monitoring approach. The objective of this rule based system, PLETCHSY, is to create a program combining statistical process control (SPC) and fault diagnosis to help control a manufacturing process which varies over time. This can be achieved by building a process control system (PCS) with the following characteristics. A facility to monitor the performance of the process by obtaining and analyzing the data relating to the appropriate process variables. Process sensor/status signals are input into an SPC module. If trends are present, the SPC module outputs the last seven control points, a pattern which is represented by either regression or scoring. The pattern is passed to the rule-based module. When the rule-based system recognizes a pattern, it starts the diagnostic process using the pattern. If the process is considered to be going out of control, advice is provided about actions which should be taken to bring the process back into control.

  10. Alternative process for thin layer etching: Application to nitride spacer etching stopping on silicon germanium

    SciTech Connect

    Posseme, N. Pollet, O.; Barnola, S.

    2014-08-04

    Silicon nitride spacer etching realization is considered today as one of the most challenging of the etch process for the new devices realization. For this step, the atomic etch precision to stop on silicon or silicon germanium with a perfect anisotropy (no foot formation) is required. The situation is that none of the current plasma technologies can meet all these requirements. To overcome these issues and meet the highly complex requirements imposed by device fabrication processes, we recently proposed an alternative etching process to the current plasma etch chemistries. This process is based on thin film modification by light ions implantation followed by a selective removal of the modified layer with respect to the non-modified material. In this Letter, we demonstrate the benefit of this alternative etch method in term of film damage control (silicon germanium recess obtained is less than 6 A), anisotropy (no foot formation), and its compatibility with other integration steps like epitaxial. The etch mechanisms of this approach are also addressed.

  11. Feedback control of chlorine inductively coupled plasma etch processing

    SciTech Connect

    Lin Chaung; Leou, K.-C.; Shiao, K.-M.

    2005-03-01

    Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2{sup 2} factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained.

  12. Advanced Simulation Technology to Design Etching Process on CMOS Devices

    NASA Astrophysics Data System (ADS)

    Kuboi, Nobuyuki

    2015-09-01

    Prediction and control of plasma-induced damage is needed to mass-produce high performance CMOS devices. In particular, side-wall (SW) etching with low damage is a key process for the next generation of MOSFETs and FinFETs. To predict and control the damage, we have developed a SiN etching simulation technique for CHxFy/Ar/O2 plasma processes using a three-dimensional (3D) voxel model. This model includes new concepts for the gas transportation in the pattern, detailed surface reactions on the SiN reactive layer divided into several thin slabs and C-F polymer layer dependent on the H/N ratio, and use of ``smart voxels''. We successfully predicted the etching properties such as the etch rate, polymer layer thickness, and selectivity for Si, SiO2, and SiN films along with process variations and demonstrated the 3D damage distribution time-dependently during SW etching on MOSFETs and FinFETs. We confirmed that a large amount of Si damage was caused in the source/drain region with the passage of time in spite of the existing SiO2 layer of 15 nm in the over etch step and the Si fin having been directly damaged by a large amount of high energy H during the removal step of the parasitic fin spacer leading to Si fin damage to a depth of 14 to 18 nm. By analyzing the results of these simulations and our previous simulations, we found that it is important to carefully control the dose of high energy H, incident energy of H, polymer layer thickness, and over-etch time considering the effects of the pattern structure, chamber-wall condition, and wafer open area ratio. In collaboration with Masanaga Fukasawa and Tetsuya Tatsumi, Sony Corporation. We thank Mr. T. Shigetoshi and Mr. T. Kinoshita of Sony Corporation for their assistance with the experiments.

  13. Carrier-lifetime-controlled selective etching process for semiconductors using photochemical etching

    DOEpatents

    Ashby, Carol I. H.; Myers, David R.

    1992-01-01

    The minority carrier lifetime is significantly much shorter in semiconductor materials with very high impurity concentrations than it is in semiconductor materials with lower impurity concentration levels. This phenomenon of reduced minority carrier lifetime in semiconductor materials having high impurity concentration is utilized to advantage for permitting highly selective semiconductor material etching to be achieved using a carrier-driven photochemical etching reaction. Various means may be employed for increasing the local impurity concentration level in specific near-surface regions of a semiconductor prior to subjecting the semiconductor material to a carrier-driven photochemical etching reaction. The regions having the localized increased impurity concentration form a self-aligned mask inhibiting photochemical etching at such localized regions while the adjacent regions not having increased impurity concentrations are selectively photochemically etched. Liquid- or gas-phase etching may be performed.

  14. A versatile masking process for plasma etched backside via holes in GaAs

    NASA Astrophysics Data System (ADS)

    Howard, A. J.; Shul, R. J.; Lovejoy, M. L.; Word, J. C.

    We have developed a versatile backside via patterning process for a visible transmission modulator application. The vias are processed on mechanically thinned (approximately)100 micrometers thick GaAs using a (approximately)45 micrometers thick, negative tone, photo definable Polyimide mask and Reaction Ion Etch (RIE) plasma etching. The Polyimide masking process was found to be superior in both etch resistance and ease of use (more robust process, thicker, straighter sidewall Profile films, were more easily attained) to masking with standard optical photoresist. With the improved etch resistance (GaAs-to-polyimide etch selectivities of 10:1) we were able to Optimize Cl2-based plasma chemistries and etching conditions to achieve high GaAs etch rates in the RIE exceeding 5.0 micrometers/min. These etch optimization results along with our novel via patterning process are reported in this paper.

  15. Optimization of chemical etching process in niobium cavities

    SciTech Connect

    Tajima, T.; Trabia, M.; Culbreth, W.; Subramanian, S.

    2004-01-01

    Superconducting niobium cavities are important components of linear accelerators. Buffered chemical polishing (BCP) on the inner surface of the cavity is a standard procedure to improve its performance. The quality of BCP, however, has not been optimized well in terms of the uniformity of surface smoothness. A finite element computational fluid dynamics (CFD) model was developed to simulate the chemical etching process inside the cavity. The analysis confirmed the observation of other researchers that the iris section of the cavity received more etching than the equator regions due to higher flow rate. The baffle, which directs flow towards the walls of the cavity, was redesigned using optimization techniques. The redesigned baffle significantly improves the performance of the etching process. To verify these results an experimental setup for flow visualization was created. The setup consists of a high speed, high resolution CCD camera. The camera is positioned by a computer-controlled traversing mechanism. A dye injecting arrangement is used for tracking the fluid path. Experimental results are in general agreement with CFD and optimization results.

  16. Optical and electrical diagnostics of fluorocarbon plasma etching processes

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul

    1999-05-01

    This article reviews recent work concerning the role of CF and CF2 radicals in etching and polymerization processes occurring in capacitively coupled radio-frequency plasmas in fluorocarbon gases used for the selective etching of SiO2 layers in microelectronic device fabrication. Laser-induced fluorescence (LIF) was used to determine time-resolved axial concentration profiles of these species in continuous and pulse-modulated CF4 and C2F6 plasmas. Calibration techniques, including broad-band UV absorption spectroscopy, were developed to put the LIF measurements on an absolute scale. A novel technique was used to determine the ion flux to the reactor walls in these polymerizing environments. The mass distribution of the ions arriving at the reactor walls was determined using a quadrupole mass spectrometer. It was found that CFx radicals are produced predominantly by the reflection of neutralized and dissociated CFx+ ions at the powered electrode surface. When the fluorine atom concentration is high, the CFx radicals are destroyed effectively by recombination catalysed by the reactor walls. When the fluorine atom concentration is lowered, the CF2 concentration rises markedly, and it participates in gas-phase oligomerization processes, forming large CxFy molecules and, after ionization, large CxFy+ ions. These species appear to be the true polymer precursors. This mechanism explains the well known correlation between high CF2 concentrations, polymer deposition and SiO2 over Si etch selectivity.

  17. Multi-layer VEB modeling: capturing interlayer etch process effects for multi-patterning process

    NASA Astrophysics Data System (ADS)

    Hu, Lin; Jung, Sunwook; Li, Jianliang; Kim, Young; Bar, Yuval; Lobb, Granger; Liang, Jim; Ogino, Atsushi; Sturtevant, John; Bailey, Todd

    2016-03-01

    Self-Aligned Via (SAV) process is commonly used in back end of line (BEOL) patterning. As the technology node advances, tightening CD and overlay specs require continuous improvement in model accuracy of the SAV process. Traditional single layer Variable Etch Bias (VEB) model is capable of describing the micro-loading and aperture effects associated with the reactive ion etch (RIE), but it does not include effects from under layers. For the SAV etch, a multi-layer VEB model is needed to account for the etch restriction from metal trenches. In this study, we characterize via post-etch dimensions through pitch and through metal trench widths, and show that VEB model prediction accuracy for SAV CDs after SAV formation can be significantly improved by applying a multi-layer scheme. Using a multi-layer VEB, it is demonstrated that the output via size changes with varying trench dimensions, which matches the silicon results. The model also reports via shape post-etch as a function of trench environment, where elliptical vias are correctly produced. The multi-layer VEB model can be applied both multi-layer correction and verification in full chip flow. This paper will also suggest that the multi-layer VEB model can be used in other FEOL layers with interlayer etch process effects, such as gate cut, to support the robustness of new model.

  18. Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

    NASA Astrophysics Data System (ADS)

    Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

    2016-10-01

    Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

  19. Performance enhancement of IPMC by anisotropic plasma etching process

    NASA Astrophysics Data System (ADS)

    Lee, Seok Hwan; Kim, Chul-Jin; Hwang, Hyun-Woo; Kim, Sung-Joo; Yang, Hyun-Seok; Park, No-Cheol; Park, Young-Pil; Park, Kang-Ho; Lee, Hyung-Kun; Choi, Nak-Jin

    2009-03-01

    Ionic Polymer-Metal Composites (IPMCs) of EAP actuators is famous for its good property of response and durability. The performance of Ionic Polymer-Metal Composites (IPMCs) is an important issue which is affected by many factors. There are two factors for deciding the performance of IPMC. By treating anisotropic plasma etching process to 6 models of the IPMCs, enhanced experimental displacement and force results are obtained. Plasma patterning processes are executed by changing the groove and the land length of 6 patterns. The purpose of the present investigation is to find out the major factor which mainly affects the IPMC performance. Simulations using ANSYS have been executed to compare with the experimental results about the values and the tendency of data. Experimental and simulating data of the performances seem to have similar tendency. In the next part of the paper, we observed the other properties like capacitance, resistance and stiffness of 6 plasma patterned IPMCs. And we observed that the stiffness is the major factor which affects the performance of IPMCs. As we seen, our problem has been reduced to investigate about the property of stiffness. We suggest that the stiffness is largely changed mainly because of the different thickness of Platinum stacked of the groove and the land part which are produced by anisotropic plasma etching processes. And we understand that anisotropic plasma patterned IPMCs of better performance can be applied to various applications.

  20. Optimization of silver-assisted nano-pillar etching process in silicon

    NASA Astrophysics Data System (ADS)

    Azhari, Ayu Wazira; Sopian, Kamaruzzaman; Desa, Mohd Khairunaz Mat; Zaidi, Saleem H.

    2015-12-01

    In this study, a respond surface methodology (RSM) model is developed using three-level Box-Behnken experimental design (BBD) technique. This model is developed to investigate the influence of metal-assisted chemical etching (MACE) process variables on the nanopillars profiles created in single crystalline silicon (Si) substrate. Design-Expert® software (version 7.1) is employed in formulating the RSM model based on five critical process variables: (A) concentration of silver (Ag), (B) concentration of hydrofluoric acid (HF), (C) concentration of hydrogen peroxide (H2O2), (D) deposition time, and (E) etching time. This model is supported by data from 46 experimental configurations. Etched profiles as a function of lateral etching rate, vertical etching rate, height, size and separation between the Si trenches and etching uniformity are characterized using field emission scanning electron microscope (FE-SEM). A quadratic regression model is developed to correlate critical process variables and is validated using the analysis of variance (ANOVA) methodology. The model exhibits near-linear dependence of lateral and vertical etching rates on both the H2O2 concentration and etching time. The predicted model is in good agreement with the experimental data where R2 is equal to 0.80 and 0.67 for the etching rate and lateral etching respectively. The optimized result shows minimum lateral etching with the average pore size of about 69 nm while the maximum etching rate is estimated at around 360 nm/min. The model demonstrates that the etching process uniformity is not influenced by either the etchant concentration or the etching time. This lack of uniformity could be attributed to the surface condition of the wafer. Optimization of the process parameters show adequate accuracy of the model with acceptable percentage errors of 6%, 59%, 1.8%, 38% and 61% for determination of the height, separation, size, the pore size and the etching rate respectively.

  1. Porous siliconformation and etching process for use in silicon micromachining

    DOEpatents

    Guilinger, Terry R.; Kelly, Michael J.; Martin, Jr., Samuel B.; Stevenson, Joel O.; Tsao, Sylvia S.

    1991-01-01

    A reproducible process for uniformly etching silicon from a series of micromechanical structures used in electrical devices and the like includes providing a micromechanical structure having a silicon layer with defined areas for removal thereon and an electrochemical cell containing an aqueous hydrofluoric acid electrolyte. The micromechanical structure is submerged in the electrochemical cell and the defined areas of the silicon layer thereon are anodically biased by passing a current through the electrochemical cell for a time period sufficient to cause the defined areas of the silicon layer to become porous. The formation of the depth of the porous silicon is regulated by controlling the amount of current passing through the electrochemical cell. The micromechanical structure is then removed from the electrochemical cell and submerged in a hydroxide solution to remove the porous silicon. The process is subsequently repeated for each of the series of micromechanical structures to achieve a reproducibility better than 0.3%.

  2. Low-frequency process for silicon-on-insulator deep reactive ion etching

    NASA Astrophysics Data System (ADS)

    Wasilik, Matthew; Pisano, Albert P.

    2001-11-01

    Due to the inherently non-uniform etching effects in the standard DRIE (Deep Reactive Ion Etch) process, a new technique has been developed specifically for SOI (silicon on insulator) etching. The new system embodies a separate LF power supply that is pulsed when being applied to the platen during the etch cycle. This lends itself to assisting in the reduction of ionic charging at the insulator layer in deep trenches. Consequently, notching or footing of Si structures is disallowed. From this a decrease in over etch sensitivity emerges, with the end result being the ability to produce high-quality, large aspect ratio structures. Si etch rates in the same DRIE process may differ due to three basic effects: Aspect ratio dependent etch (ARDE), microloading (RIE-lag), and the general loading effect by which edges of the substrate etch faster than the center. When etching to a buried insulating layer these effects tend to indirectly encourage footing. The purpose of the research involved was to find optimal process parameters that would minimize footing. Factorial design of experiment technique was used to accomplish this in a two step process. First, main and second order effects on etch-rate uniformity were studied. Then, once supplied with process parameters that minimize uniformity effects, parameter settings that minimize footing were found. The end result is a purse of optimized DRIE-SOI recipes that produce superb high-aspect ratio Silicon structures.

  3. Process feasibility investigation of freezing free litho-litho-etch process for below 32nm hp

    NASA Astrophysics Data System (ADS)

    Nakamura, Tsuyoshi; Takeshita, Masaru; Yokoya, Jiro; Yoshii, Yasuhiro; Saito, Hirokuni; Takasu, Ryoichi; Ohmori, Katsumi

    2010-04-01

    Double patterning with 193nm immersion lithography becomes to most promising candidate for 32nm half pitch node and possibly below 32nm half pitch. Several double patterning methods have been suggested such as LELE (Litho-Etch -Litho-Etch), LLE (Litho-Litho-Etch) and Spacer defined process, however, LLE process is pointed out as low cost double patterning technique because of its simplicity. But LLE process needs new method to maintain 1st lithography pattern and additional freezing processes have been suggested In SPIE Advanced Lithography 2009, freezing free "Posi/Posi" process was introduced as candidate for LLE process. This is LLE process that uses two different positive tone photoresists without freezing process. The resist for 2nd lithography contains a specific solvent to prevent the mixing of two resists and there is an activation energy gap between 1st and 2nd resists to maintain 1st lithography pattern. The double patterning can be successfully processed by these specific resists without freezing process. In this study, the performance of this freezing free "Posi/Posi" process is investigated for pitch splitting pattern using 1.35 NA exposure tool. The imaging results including CD control capability, and etching results are collected for 32nm half pitch and below. Additionally the two-dimensional pattern imaging is also obtained for 76nm minimum pitch.

  4. Deep Reactive Ion Etching (DRIE) of High Aspect Ratio SiC Microstructures using a Time-Multiplexed Etch-Passivate Process

    NASA Technical Reports Server (NTRS)

    Evans, Laura J.; Beheim, Glenn M.

    2006-01-01

    High aspect ratio silicon carbide (SiC) microstructures are needed for microengines and other harsh environment micro-electro-mechanical systems (MEMS). Previously, deep reactive ion etching (DRIE) of low aspect ratio (AR less than or = 1) deep (greater than 100 micron) trenches in SiC has been reported. However, existing DRIE processes for SiC are not well-suited for definition of high aspect ratio features because such simple etch-only processes provide insufficient control over sidewall roughness and slope. Therefore, we have investigated the use of a time-multiplexed etch-passivate (TMEP) process, which alternates etching with polymer passivation of the etch sidewalls. An optimized TMEP process was used to etch high aspect ratio (AR greater than 5) deep (less than 100 micron) trenches in 6H-SiC. Power MEMS structures (micro turbine blades) in 6H-SiC were also fabricated.

  5. A novel process of etching EUV masks for future generation technology

    NASA Astrophysics Data System (ADS)

    Wu, Banqiu; Kumar, Ajay; Chandrachood, Madhavi; Ibrahim, Ibrahim; Sabharwal, Amitabh

    2006-10-01

    Studies on pattern transfer of next generation lithographic (EUV) photomask were carried out. Based on current absorber layer material candidates, thermodynamic calculations were performed and plasma etch gas system and composition were investigated. The gas systems have the advantage of all etch products being in volatile condition. This is helpful to keep the etch process and etch chamber clean. For etch CD bias challenge in EUV photomask etch, self-mask concept was investigated, which makes anti-reflective (AR) sub-layer of the absorber layer function as a hard mask for the bulk absorber layer beneath. It significantly reduces etch CD bias and improves pattern transfer fidelity. For common candidates of EUV mask absorber layers such as TaBO/TaBN and TaSiON/TaSi, reactive gas systems were proposed according to thermodynamic calculations with all products volatile. AR sub-layers were etched in one gas composition with volatiles. Once the AR sub-layer is etched through, gas composition was changed so that the bulk absorber sub-layer beneath is etched selectively with volatile products. Excellent results in profiles, CD bias, CD uniformity, and underneath buffer/capping layer impact have been demonstrated.

  6. Thermal compression chip interconnection using organic solderability preservative etched substrate by plasma processing.

    PubMed

    Cho, Sung-Won; Choi, JoonYoung; Chung, Chin-Wook

    2014-12-01

    The solderability of copper organic solderbility preservative (CuOSP) finished substrate was enhanced by the plasma etching. To improve the solderability of TC interconnection with the CuOSP finished substrate, the plasma etching process is used. An Oxygen-Hydrogen plasma treatment process is performed to remove OSP material. To prevent the oxidation by oxygen plasma treatment, hydrogen reducing process is also performed before TC interconnection process. The thickness of OSP material after plasma etching is measured by optical reflection method and the component analysis by Auger Electron Spectroscopy is performed. From the lowered thickness, the bonding force of TC interconnection after OSP etching process is lowered. Also the electrical open/short test was performed after assembling the completed semiconductor packaging. The improved yield due to the plasma etching process is achieved.

  7. Advanced simulation technology for etching process design for CMOS device applications

    NASA Astrophysics Data System (ADS)

    Kuboi, Nobuyuki; Fukasawa, Masanaga; Tatsumi, Tetsuya

    2016-07-01

    Plasma etching is a critical process for the realization of high performance in the next generation of CMOS devices. To predict and control fluctuations in the etching properties accurately during mass production, it is essential that etching process simulation technology considers fluctuations in the plasma chamber wall conditions, the effects of by-products on the critical dimensions, the Si recess dependence on the wafer open area ratio and local pattern structure, and the time-dependent plasma-induced damage distribution associated with the three-dimensional feature scale profile at the 100 nm level. This consideration can overcome the issues with conventional simulations performed under the assumed ideal conditions, which are not accurate enough for practical process design. In this article, these advanced process simulation technologies are reviewed, and, from the results of suitable process simulations, a new etching system that automatically controls the etching properties is proposed to enable stable CMOS device fabrication with high yields.

  8. Summary of Chalcogenide Glass Processing: Wet-Etching and Photolithography

    SciTech Connect

    Riley, Brian J.; Sundaram, S. K.; Johnson, Bradley R.; Saraf, Laxmikant V.

    2006-12-01

    This report describes a study designed to explore the different properties of two different chalcogenide materials, As2S3 and As24S38Se38, when subjected to photolithographic wet-etching techniques. Chalcogenide glasses are made by combining chalcogen elements S, Se, and Te with Group IV and/or V elements. The etchant was selected from the literature and was composed of sodium hydroxide, isopropyl alcohol, and deionized water and the types of chalcogenide glass for study were As2S3 and As24S38Se38. The main goals here were to obtain a single variable etch rate curve of etch depth per time versus NaOH overall solution concentration in M and to see the difference in etch rate between a given etchant when used on the different chalcogenide stoichiometries. Upon completion of these two goals, future studies will begin to explore creating complex, integrated photonic devices via these methods.

  9. Deep Etching Process Developed for the Fabrication of Silicon Carbide Microsystems

    NASA Technical Reports Server (NTRS)

    Beheim, Glenn M.

    2000-01-01

    Silicon carbide (SiC), because of its superior electrical and mechanical properties at elevated temperatures, is a nearly ideal material for the microminiature sensors and actuators that are used in harsh environments where temperatures may reach 600 C or greater. Deep etching using plasma methods is one of the key processes used to fabricate silicon microsystems for more benign environments, but SiC has proven to be a more difficult material to etch, and etch depths in SiC have been limited to several micrometers. Recently, the Sensors and Electronics Technology Branch at the NASA Glenn Research Center at Lewis Field developed a plasma etching process that was shown to be capable of etching SiC to a depth of 60 mm. Deep etching of SiC is achieved by inductive coupling of radiofrequency electrical energy to a sulfur hexafluoride (SF6) plasma to direct a high flux of energetic ions and reactive fluorine atoms to the SiC surface. The plasma etch is performed at a low pressure, 5 mtorr, which together with a high gas throughput, provides for rapid removal of the gaseous etch products. The lateral topology of the SiC microstructure is defined by a thin film of etch-resistant material, such as indium-tin-oxide, which is patterned using conventional photolithographic processes. Ions from the plasma bombard the exposed SiC surfaces and supply the energy needed to initiate a reaction between SiC and atomic fluorine. In the absence of ion bombardment, no reaction occurs, so surfaces perpendicular to the wafer surface (the etch sidewalls) are etched slowly, yielding the desired vertical sidewalls.

  10. Solar cell efficiency enhancement by junction etching and conductive AR coating processes

    NASA Astrophysics Data System (ADS)

    Mardesich, N.

    Discussions on some injectable processes for enhancing the response of low cost terrestrial solar cells are presented. The procedure consists of (1) reduction of junction depth and removal of diffusion damage and defects by suitable etching processes after application of front contact and (2) reduction of light reflection and an increase in sheet conductivity by sputtering a conductive ITO AR coat on the etch front surface. By combining the two processes of plasma etching and ITO AR coating, a 43% total increase in short circuit current is expected for a cell with initial 3000 A junction depth.

  11. Process for Smoothing an Si Substrate after Etching of SiO2

    NASA Technical Reports Server (NTRS)

    Turner, Tasha; Wu, Chi

    2003-01-01

    A reactive-ion etching (RIE) process for smoothing a silicon substrate has been devised. The process is especially useful for smoothing those silicon areas that have been exposed by etching a pattern of holes in a layer of silicon dioxide that covers the substrate. Applications in which one could utilize smooth silicon surfaces like those produced by this process include fabrication of optical waveguides, epitaxial deposition of silicon on selected areas of silicon substrates, and preparation of silicon substrates for deposition of adherent metal layers. During etching away of a layer of SiO2 that covers an Si substrate, a polymer becomes deposited on the substrate, and the substrate surface becomes rough (roughness height approximately equal to 50 nm) as a result of over-etching or of deposition of the polymer. While it is possible to smooth a silicon substrate by wet chemical etching, the undesired consequences of wet chemical etching can include compromising the integrity of the SiO2 sidewalls and undercutting of the adjacent areas of the silicon dioxide that are meant to be left intact. The present RIE process results in anisotropic etching that removes the polymer and reduces height of roughness of the silicon substrate to less than 10 nm while leaving the SiO2 sidewalls intact and vertical. Control over substrate versus sidewall etching (in particular, preferential etching of the substrate) is achieved through selection of process parameters, including gas flow, power, and pressure. Such control is not uniformly and repeatably achievable in wet chemical etching. The recipe for the present RIE process is the following: Etch 1 - A mixture of CF4 and O2 gases flowing at rates of 25 to 75 and 75 to 125 standard cubic centimeters per minute (stdcm3/min), respectively; power between 44 and 55 W; and pressure between 45 and 55 mtorr (between 6.0 and 7.3 Pa). The etch rate lies between approximately equal to 3 and approximately equal to 6 nm/minute. Etch 2 - O2 gas

  12. A Silicon-Based, Sequential Coat-and-Etch Process to Fabricate Nearly Perfect Substrate Surfaces

    SciTech Connect

    Mirkarimi, P B; Spiller, E; Baker, S L; Stearns, D G; Robinson, J C; Olynick, D L; Salmassi, F; Liddle, J A; Liang, T; Stivers, A R

    2005-07-05

    For many thin-film applications substrate imperfections such as particles, pits, scratches, and general roughness, can nucleate film defects which can severely detract from the coating's performance. Previously we developed a coat-and-etch process, termed the ion beam thin film planarization process, to planarize substrate particles up to {approx} 70 nm in diameter. The process relied on normal incidence etching; however, such a process induces defects nucleated by substrate pits to grow much larger. We have since developed a coat-and-etch process to planarize {approx}70 nm deep by 70 nm wide substrate pits; it relies on etching at an off-normal incidence angle, i.e., an angle of {approx} 70{sup o} from the substrate normal. However, a disadvantage of this pit smoothing process is that it induces defects nucleated by substrate particles to grow larger. Combining elements from both processes we have been able to develop a silicon-based, coat-and-etch process to successfully planarize {approx}70 nm substrate particles and pits simultaneously to at or below 1 nm in height; this value is important for applications such as extreme ultraviolet lithography (EUVL) masks. The coat-and-etch process has an added ability to significantly reduce high-spatial frequency roughness, rendering a nearly perfect substrate surface.

  13. Multi-Step Deep Reactive Ion Etching Fabrication Process for Silicon-Based Terahertz Components

    NASA Technical Reports Server (NTRS)

    Jung-Kubiak, Cecile (Inventor); Reck, Theodore (Inventor); Chattopadhyay, Goutam (Inventor); Perez, Jose Vicente Siles (Inventor); Lin, Robert H. (Inventor); Mehdi, Imran (Inventor); Lee, Choonsup (Inventor); Cooper, Ken B. (Inventor); Peralta, Alejandro (Inventor)

    2016-01-01

    A multi-step silicon etching process has been developed to fabricate silicon-based terahertz (THz) waveguide components. This technique provides precise dimensional control across multiple etch depths with batch processing capabilities. Nonlinear and passive components such as mixers and multipliers waveguides, hybrids, OMTs and twists have been fabricated and integrated into a small silicon package. This fabrication technique enables a wafer-stacking architecture to provide ultra-compact multi-pixel receiver front-ends in the THz range.

  14. EUV process establishment through litho and etch for N7 node

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yuhei; Kawakami, Shinichiro; Kubota, Minoru; Matsunaga, Koichi; Nafus, Kathleen; Foubert, Philippe; Mao, Ming

    2016-03-01

    Extreme ultraviolet lithography (EUVL) technology is steadily reaching high volume manufacturing for 16nm half pitch node and beyond. However, some challenges, for example scanner availability and resist performance (resolution, CD uniformity (CDU), LWR, etch behavior and so on) are remaining. Advance EUV patterning on the ASML NXE:3300/ CLEAN TRACK LITHIUS Pro Z- EUV litho cluster is launched at imec, allowing for finer pitch patterns for L/S and CH. Tokyo Electron Ltd. and imec are continuously collabo rating to develop manufacturing quality POR processes for NXE:3300. TEL's technologies to enhance CDU, defectivity and LWR/LER can improve patterning performance. The patterning is characterized and optimized in both litho and etch for a more complete understanding of the final patterning performance. This paper reports on post-litho CDU improvement by litho process optimization and also post-etch LWR reduction by litho and etch process optimization.

  15. A laser dry etch process for smooth continuous relief structures in InP

    NASA Astrophysics Data System (ADS)

    Weber, H.; Matz, R.; Weimann, G.

    1996-11-01

    A laser induced etch process is described which uses a pulsed 248 nm KrF excimer laser and Cl2 atmosphere for the fabrication of monolithic continuously curved reliefs in InP substrate. In a bakeable processing chamber with low base pressure a wide range of laser fluences is available for damage-free etching. Especially, by photothermal heating far above the melting point, mirrorlike smooth surfaces are obtained. The etch rate characteristics are correlated to the maximum surface temperature reached during the laser pulse. The etch rate is independent of pressure and gas flux in the ranges 0.1 10 mbar and 20 300 sccm, respectively. It increases, however, with the background substrate temperature. Etch rates of up to 3.6 nm/pulse or 4.3 lm/min are possible at 20 Hz pulse repetition rate without visible surface damage. The process exhibits a smooth increase of the etch rate from 1 to 3 nm/pulse between 200 and 300 mJ/cm2, which could be used for making curved reliefs by optical transmission variations on the projection mask.

  16. New Deep Reactive Ion Etching Process Developed for the Microfabrication of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Evans, Laura J.; Beheim, Glenn M.

    2005-01-01

    Silicon carbide (SiC) is a promising material for harsh environment sensors and electronics because it can enable such devices to withstand high temperatures and corrosive environments. Microfabrication techniques have been studied extensively in an effort to obtain the same flexibility of machining SiC that is possible for the fabrication of silicon devices. Bulk micromachining using deep reactive ion etching (DRIE) is attractive because it allows the fabrication of microstructures with high aspect ratios (etch depth divided by lateral feature size) in single-crystal or polycrystalline wafers. Previously, the Sensors and Electronics Branch of the NASA Glenn Research Center developed a DRIE process for SiC using the etchant gases sulfur hexafluoride (SF6) and argon (Ar). This process provides an adequate etch rate of 0.2 m/min and yields a smooth surface at the etch bottom. However, the etch sidewalls are rougher than desired, as shown in the preceding photomicrograph. Furthermore, the resulting structures have sides that slope inwards, rather than being precisely vertical. A new DRIE process for SiC was developed at Glenn that produces smooth, vertical sidewalls, while maintaining an adequately high etch rate.

  17. Electronic-carrier-controlled photochemical etching process in semiconductor device fabrication

    DOEpatents

    Ashby, C.I.H.; Myers, D.R.; Vook, F.L.

    1988-06-16

    An electronic-carrier-controlled photochemical etching process for carrying out patterning and selective removing of material in semiconductor device fabrication includes the steps of selective ion implanting, photochemical dry etching, and thermal annealing, in that order. In the selective ion implanting step, regions of the semiconductor material in a desired pattern are damaged and the remainder of the regions of the material not implanted are left undamaged. The rate of recombination of electrons and holes is increased in the damaged regions of the pattern compared to undamaged regions. In the photochemical dry etching step which follows ion implanting step, the material in the undamaged regions of the semiconductor are removed substantially faster than in the damaged regions representing the pattern, leaving the ion-implanted, damaged regions as raised surface structures on the semiconductor material. After completion of photochemical dry etching step, the thermal annealing step is used to restore the electrical conductivity of the damaged regions of the semiconductor material.

  18. Electronic-carrier-controlled photochemical etching process in semiconductor device fabrication

    DOEpatents

    Ashby, Carol I. H.; Myers, David R.; Vook, Frederick L.

    1989-01-01

    An electronic-carrier-controlled photochemical etching process for carrying out patterning and selective removing of material in semiconductor device fabrication includes the steps of selective ion implanting, photochemical dry etching, and thermal annealing, in that order. In the selective ion implanting step, regions of the semiconductor material in a desired pattern are damaged and the remainder of the regions of the material not implanted are left undamaged. The rate of recombination of electrons and holes is increased in the damaged regions of the pattern compared to undamaged regions. In the photochemical dry etching step which follows ion implanting step, the material in the undamaged regions of the semiconductor are removed substantially faster than in the damaged regions representing the pattern, leaving the ion-implanted, damaged regions as raised surface structures on the semiconductor material. After completion of photochemical dry etching step, the thermal annealing step is used to restore the electrical conductivity of the damaged regions of the semiconductor material.

  19. Effects of wet etch processing on laser-induced damage of fused silica surfaces

    SciTech Connect

    Battersby, C.L.; Kozlowski, M.R.; Sheehan, L.M.

    1998-12-22

    Laser-induced damage of transparent fused silica optical components by 355 nm illumination occurs primarily at surface defects produced during the grinding and polishing processes. These defects can either be surface defects or sub-surface damage.Wet etch processing in a buffered hydrogen fluoride (HF) solution has been examined as a tool for characterizing such defects. A study was conducted to understand the effects of etch depth on the damage threshold of fused silica substrates. The study used a 355 nm, 7.5 ns, 10 Hz Nd:YAG laser to damage test fused silica optics through various wet etch processing steps. Inspection of the surface quality was performed with Nomarski microscopy and Total Internal Reflection Microscopy. The damage test data and inspection results were correlated with polishing process specifics. The results show that a wet etch exposes subsurface damage while maintaining or improving the laser damage performance. The benefits of a wet etch must be evaluated for each polishing process.

  20. Investigation of the neutral-solution etch process for refractive SOE antireflective surfaces

    SciTech Connect

    Maish, A.B.

    1991-01-01

    Antireflection of optically clear glass used in photovoltaic concentrator refractive secondary optical elements (SOE's) was investigated using the neutral-solution etch process developed by Schott Glass. Test coupons and SOE's made from barium zinc glass, which does not solarize under ultraviolet exposure, were successfully etched at the center point process variable conditions of 87{degrees}C and 24 hours. Reflectance of the plano-plano dropped from 7.7% to 0.8%, with a corresponding increase in transmission from 91.7% to 98.5%. The etching process uses non-hydrofluoric, relatively non-toxic chemicals in a low-cost process well suited for use by photovoltaic system manufacturers during production. 10 refs., 4 figs., 1 tab.

  1. On the interest of carbon-coated plasma reactor for advanced gate stack etching processes

    SciTech Connect

    Ramos, R.; Cunge, G.; Joubert, O.

    2007-03-15

    In integrated circuit fabrication the most wide spread strategy to achieve acceptable wafer-to-wafer reproducibility of the gate stack etching process is to dry-clean the plasma reactor walls between each wafer processed. However, inherent exposure of the reactor walls to fluorine-based plasma leads to formation and accumulation of nonvolatile fluoride residues (such as AlF{sub x}) on reactor wall surfaces, which in turn leads to process drifts and metallic contamination of wafers. To prevent this while keeping an Al{sub 2}O{sub 3} reactor wall material, a coating strategy must be used, in which the reactor is coated by a protective layer between wafers. It was shown recently that deposition of carbon-rich coating on the reactor walls allows improvements of process reproducibility and reactor wall protection. The authors show that this strategy results in a higher ion-to-neutral flux ratio to the wafer when compared to other strategies (clean or SiOCl{sub x}-coated reactors) because the carbon walls load reactive radical densities while keeping the same ion current. As a result, the etching rates are generally smaller in a carbon-coated reactor, but a highly anisotropic etching profile can be achieved in silicon and metal gates, whose etching is strongly ion assisted. Furthermore, thanks to the low density of Cl atoms in the carbon-coated reactor, silicon etching can be achieved almost without sidewall passivation layers, allowing fine critical dimension control to be achieved. In addition, it is shown that although the O atom density is also smaller in the carbon-coated reactor, the selectivity toward ultrathin gate oxides is not reduced dramatically. Furthermore, during metal gate etching over high-k dielectric, the low level of parasitic oxygen in the carbon-coated reactor also allows one to minimize bulk silicon reoxidation through HfO{sub 2} high-k gate dielectric. It is then shown that the BCl{sub 3} etching process of the HfO{sub 2} high-k material is highly

  2. Reaction ion etching process for improving laser damage resistance of fused silica optical surface.

    PubMed

    Sun, Laixi; Liu, Hongjie; Huang, Jin; Ye, Xin; Xia, Handing; Li, Qingzhi; Jiang, Xiaodong; Wu, Weidong; Yang, Liming; Zheng, Wanguo

    2016-01-11

    Laser induced damage of fused silica optics occurs primarily on optical surface or subsurface resulting from various defects produced during polishing/grinding process. Many new kinds of surface treatment processes are explored to remove or control the defects on fused silica surface. In this study, we report a new application of reaction ion etching (RIE)-based surface treatment process for manufacture of high quality fused silica optics. The influence of RIE processes on laser damage resistance as a function of etching depth and the evolution of typical defects which are associated with laser damage performance were investigated. The results show that the impurity element defects and subsurface damage on the samples surface were efficiently removed and prevented. Pure silica surface with relatively single-stable stoichiometry and low carbon atomic concentration was created during the etching. The laser damage resistance of the etched samples increased dramatically. The increase of roughness and ODC point defect with deeper etching are believed to be the main factors to limit further increase of the damage resistance of fused silica. The study is expected to contribute to the development of fused silica optics with high resistance to laser induced degradation in the future. PMID:26832251

  3. Deep silicon etch for biology MEMS fabrication: review of process parameters influence versus chip design

    NASA Astrophysics Data System (ADS)

    Magis, T.; Ballerand, S.; Bellemin Comte, A.; Pollet, Olivier

    2013-03-01

    Micro-system for biology is a growing market, especially for micro-fluidic applications (environment and health). Key part for the manufacturing of biology MEMS is the deep silicon etching by plasma to create microstructures. Usual etching process as an alternation of etching and passivation steps is a well-known method for MEMS fabrication, nowadays used in high volume production for devices like sensors and actuators. MEMS for biology applications are very different in design compared to more common micro-systems like accelerometers for instance. Indeed, their design includes on the same chip structures of very diverse size like narrow pillars, large trenches and wide cavities. This makes biology MEMS fabrication very challenging for DRIE, since each type of feature considered individually would require a specific etch process. Furthermore process parameters suited to match specifications on small size features (vertical profile, low sidewall roughness) induce issues and defects on bigger structures (undercut, micro-masking) and vice versa. Thus the process window is constrained leading to trade-offs in process development. In this paper process parameters such as source and platen powers, pressure, etching and passivation gas flows and steps duration were investigated to achieve all requirements. As well interactions between those different factors were characterized at different levels, from individual critical feature up to chip scale and to wafer scale. We will show the plasma process development and tuning to reach all these specifications. We also compared different chambers configurations of our ICP tool (source wafer distance, plasma diffusion) in order to obtain a good combination of hardware and process. With optimized etching we successfully fabricate micro-fluidic devices like micro-pumps.

  4. Dry etching of metallization

    NASA Technical Reports Server (NTRS)

    Bollinger, D.

    1983-01-01

    The production dry etch processes are reviewed from the perspective of microelectronic fabrication applications. The major dry etch processes used in the fabrication of microelectronic devices can be divided into two categories - plasma processes in which samples are directly exposed to an electrical discharge, and ion beam processes in which samples are etched by a beam of ions extracted from a discharge. The plasma etch processes can be distinguished by the degree to which ion bombardment contributes to the etch process. This, in turn is related to capability for anisotropic etching. Reactive Ion Etching (RIE) and Ion Beam Etching are of most interest for etching of thin film metals. RIE is generally considered the best process for large volume, anisotropic aluminum etching.

  5. Finding practical phenomenological models that include both photoresist behavior and etch process effects

    NASA Astrophysics Data System (ADS)

    Jung, Sunwook; Do, Thuy; Sturtevant, John

    2015-03-01

    For more than five decades, the semiconductor industry has overcome technology challenges with innovative ideas that have continued to enable Moore's Law. It is clear that multi-patterning lithography is vital for 20nm half pitch using 193i. Multi-patterning exposure sequences and pattern multiplication processes can create complicated tolerance accounting due to the variability associated with the component processes. It is essential to ensure good predictive accuracy of compact etch models used in multipatterning simulation. New modelforms have been developed to account for etch bias behavior at 20 nm and below. The new modeling components show good results in terms of global fitness and some improved predication capability for specific features. We've also investigated a new methodology to make the etch model aware of 3D resist profiles.

  6. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    SciTech Connect

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  7. Silicon Wafer Surface-Temperature Monitoring System for Plasma Etching Process

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Ishii, J.; Nakaoka, A.; Mizojiri, Y.

    2011-08-01

    A thermoreflectance temperature measuring system was developed with the aim to realize monitoring of the silicon wafer surface temperature during plasma etching. The thermoreflectance detects variations in temperature through changes in optical reflectance. To overcome such difficulties as low sensitivity and limitation in installation space and position for in situ measurements, the differential thermoreflectance utilizing two orthogonal polarizations was introduced. Noise such as fluctuations in the incident beam intensity or changes of loss in the optical path would affect both polarizations equally and would not affect the measurement. The large angle of incidence of the beam allows measurement to be performed from outside the viewing ports of existing plasma etching process chambers through the gap between the plasma electrode and the silicon wafer. In this article, an off-line measurement result is presented, with results for bare wafers as well as for wafers with metal depositions. A prototype system developed for tests in plasma etching facilities in a production line is described.

  8. A Simple Single Step diffusion and Emitter Etching Process for High Efficiency Gallium Antimonide Thermophotovoltaic Devices

    SciTech Connect

    G. Rajagopalan; N.S. Reddy; E. Ehsani; I.B. Bhat; P.S. Dutta; R.J. Gutmann; G. Nichols; G.W. Charache; O. Sulima

    2003-08-29

    A single step diffusion followed by precise etching of the diffused layer has been developed to obtain a diffusion profile appropriate for high efficiency GaSb thermophotovoltaic cells. The junction depth was controlled through monitoring of light current-voltage (I-V) curves (photovoltaic response) during the post diffusion emitter etching process. The measured photoresponses (prior to device fabrication) have been correlated with the quantum efficiencies and the open circuit voltages in the fabricated devices. An optimum junction depth for obtaining highest quantum efficiency and open circuit voltage is presented based on diffusion lengths (or monitoring carrier lifetimes), carrier mobility and typical diffused impurity profile in GaSb.

  9. Modeling a Dry Etch Process for Large-Area Devices

    SciTech Connect

    Buss, R.J.; Hebner, G.A.; Ruby, D.S.; Yang, P.

    1999-07-28

    There has been considerable interest in developing dry processes which can effectively replace wet processing in the manufacture of large area photovoltaic devices. Environmental and health issues are a driver for this activity because wet processes generally increase worker exposure to toxic and hazardous chemicals and generate large volumes of liquid hazardous waste. Our work has been directed toward improving the performance of screen-printed solar cells while using plasma processing to reduce hazardous chemical usage.

  10. Similarity ratio analysis for early stage fault detection with optical emission spectrometer in plasma etching process.

    PubMed

    Yang, Jie; McArdle, Conor; Daniels, Stephen

    2014-01-01

    A Similarity Ratio Analysis (SRA) method is proposed for early-stage Fault Detection (FD) in plasma etching processes using real-time Optical Emission Spectrometer (OES) data as input. The SRA method can help to realise a highly precise control system by detecting abnormal etch-rate faults in real-time during an etching process. The method processes spectrum scans at successive time points and uses a windowing mechanism over the time series to alleviate problems with timing uncertainties due to process shift from one process run to another. A SRA library is first built to capture features of a healthy etching process. By comparing with the SRA library, a Similarity Ratio (SR) statistic is then calculated for each spectrum scan as the monitored process progresses. A fault detection mechanism, named 3-Warning-1-Alarm (3W1A), takes the SR values as inputs and triggers a system alarm when certain conditions are satisfied. This design reduces the chance of false alarm, and provides a reliable fault reporting service. The SRA method is demonstrated on a real semiconductor manufacturing dataset. The effectiveness of SRA-based fault detection is evaluated using a time-series SR test and also using a post-process SR test. The time-series SR provides an early-stage fault detection service, so less energy and materials will be wasted by faulty processing. The post-process SR provides a fault detection service with higher reliability than the time-series SR, but with fault testing conducted only after each process run completes. PMID:24755865

  11. Similarity ratio analysis for early stage fault detection with optical emission spectrometer in plasma etching process.

    PubMed

    Yang, Jie; McArdle, Conor; Daniels, Stephen

    2014-01-01

    A Similarity Ratio Analysis (SRA) method is proposed for early-stage Fault Detection (FD) in plasma etching processes using real-time Optical Emission Spectrometer (OES) data as input. The SRA method can help to realise a highly precise control system by detecting abnormal etch-rate faults in real-time during an etching process. The method processes spectrum scans at successive time points and uses a windowing mechanism over the time series to alleviate problems with timing uncertainties due to process shift from one process run to another. A SRA library is first built to capture features of a healthy etching process. By comparing with the SRA library, a Similarity Ratio (SR) statistic is then calculated for each spectrum scan as the monitored process progresses. A fault detection mechanism, named 3-Warning-1-Alarm (3W1A), takes the SR values as inputs and triggers a system alarm when certain conditions are satisfied. This design reduces the chance of false alarm, and provides a reliable fault reporting service. The SRA method is demonstrated on a real semiconductor manufacturing dataset. The effectiveness of SRA-based fault detection is evaluated using a time-series SR test and also using a post-process SR test. The time-series SR provides an early-stage fault detection service, so less energy and materials will be wasted by faulty processing. The post-process SR provides a fault detection service with higher reliability than the time-series SR, but with fault testing conducted only after each process run completes.

  12. Quantum cascade laser based monitoring of CF2 radical concentration as a diagnostic tool of dielectric etching plasma processes

    NASA Astrophysics Data System (ADS)

    Hübner, M.; Lang, N.; Zimmermann, S.; Schulz, S. E.; Buchholtz, W.; Röpcke, J.; van Helden, J. H.

    2015-01-01

    Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF2 radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF2 radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm-1. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν3 fundamental band of CF2 with the aid of an improved simulation of the line strengths. We found that the CF2 radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.

  13. Process optimization for lattice-selective wet etching of crystalline silicon structures

    NASA Astrophysics Data System (ADS)

    Dixson, Ronald G.; Guthrie, William F.; Allen, Richard A.; Orji, Ndubuisi G.; Cresswell, Michael W.; Murabito, Christine E.

    2016-01-01

    Lattice-selective etching of silicon is used in a number of applications, but it is particularly valuable in those for which the lattice-defined sidewall angle can be beneficial to the functional goals. A relatively small but important niche application is the fabrication of tip characterization standards for critical dimension atomic force microscopes (CD-AFMs). CD-AFMs are commonly used as reference tools for linewidth metrology in semiconductor manufacturing. Accurate linewidth metrology using CD-AFM, however, is critically dependent upon calibration of the tip width. Two national metrology institutes and at least two commercial vendors have explored the development of tip calibration standards using lattice-selective etching of crystalline silicon. The National Institute of Standards and Technology standard of this type is called the single crystal critical dimension reference material. These specimens, which are fabricated using a lattice-plane-selective etch on (110) silicon, exhibit near vertical sidewalls and high uniformity and can be used to calibrate CD-AFM tip width to a standard uncertainty of less than 1 nm. During the different generations of this project, we evaluated variations of the starting material and process conditions. Some of our starting materials required a large etch bias to achieve the desired linewidths. During the optimization experiment described in this paper, we found that for potassium hydroxide etching of the silicon features, it was possible to independently tune the target linewidth and minimize the linewidth nonuniformity. Consequently, this process is particularly well suited for small-batch fabrication of CD-AFM linewidth standards.

  14. The study of influence of the gas flow rate to etched layer thickness, and roughness of the anisotropy field of gallium arsenide is etched in the plasma chemical etching process

    NASA Astrophysics Data System (ADS)

    Ageev, O. A.; Klimin, V. S.; Solodovnik, M. S.; Eskov, A. V.; Krasnoborodko, S. Y.

    2016-08-01

    In the experiments on the etched surface of gallium arsenide were performed. We studied the effect of BCl3 gas flow rate on the thickness of the etched layer. GaAs etching rate was: 537,4 nm/min 28,7 nm/min 2,6 nm/min, the values of the flow rate of BCl3 NBCl3 - 15, 10, 5 cc/min, respectively. The effect of BCl3 gas flow rate to the mean-square roughness of the etched surface. The influence of the anisotropy of the process on the geometry of the etched area. Revealed that the deflection angle for the samples treated with the working gas flow rate NBCl3 - 15 cc/min in the [110] direction was α [110] = 65,5° in direction [111] was α [111] = 45,58°. For samples treated with the working gas flow rate NBCl3 - 10 cc/min in the [110] direction was α [110] = 20,94° in direction [111] was α [111] = 11,37°. For samples treated with the working gas flow rate NBCl3 - 5 cc/min in the [110] was α [110] = 0,32° in direction [111] was α [111] = 0,21°. The results can be used to produce discrete diodes, heterojunction devices, and other results.

  15. Crackless linear through-wafer etching of Pyrex glass using liquid-assisted CO2 laser processing

    NASA Astrophysics Data System (ADS)

    Chung, C. K.; Sung, Y. C.; Huang, G. R.; Hsiao, E. J.; Lin, W. H.; Lin, S. L.

    2009-03-01

    Pyrex glass etching is an important technology for the microfluid application to lab-on-a-chip devices, but suffers from very low etching rate and mask-requiring process in conventional HF/BOE wet or plasma dry etching as well as thermal induced crack surface by CO2 laser processing. In this paper, we applied the liquid-assisted laser processing (LALP) method for linear through-wafer deep etching of Pyrex glass without mask materials to obtain a crackless surface at very fast etching rates up to 25 μm/s for a 20 mm long trench. The effect of laser scanning rate and water depth on the etching of the 500 μm thick Pyrex glass immersed in liquid water was investigated. The smooth surface without cracks can be achieved together with the much reduced height of bulge via an appropriate parameter control. A mechanism of thermal stress reduction in water and shear-force-enhanced debris removal is discussed. The quality improvement of glass etching using LALP is due to the cooling effect of the water to reduce the temperature gradient for a crackless surface and natural convection during etching to carry away the debris for diminishing bulge formation.

  16. Relationship between gas-phase chemistries and surface processes in fluorocarbon etch plasmas: A process rate model

    SciTech Connect

    Sant, S. P.; Nelson, C. T.; Overzet, L. J.; Goeckner, M. J.

    2009-07-15

    In a typical plasma tool, both etch and deposition occur simultaneously. Extensive experimental measurements are used to help develop a general model of etch and deposition processes. This model employs reaction probabilities, or surface averaged cross sections, to link the measurable surface processes, etch and deposition, to the flux of various species to the surfaces. Because the cross sections are quantum mechanical in nature, this surface rate model should be applicable to many low temperature plasma processing systems. Further, the parameters that might be important in reaction cross sections are known from quantum mechanics, e.g., species, energy, temperature, and impact angle. Such parameters might vary from system to system, causing the wide processing variability observed in plasma tools. Finally the model is used to compare measurements of ion flux, ion energy, and fluorocarbon radical flux to the measured process rates. It is found that the model appears to be consistent with calculations of gain/loss rates for the various radicals present in the discharge as well as measured etch and deposition rates.

  17. Challenges in the Plasma Etch Process Development in the sub-20nm Technology Nodes

    NASA Astrophysics Data System (ADS)

    Kumar, Kaushik

    2013-09-01

    For multiple generations of semiconductor technologies, RF plasmas have provided a reliable platform for critical and non-critical patterning applications. The electron temperature of processes in a RF plasma is typically several electron volts. A substantial portion of the electron population is within the energy range accessible for different types of electron collision processes, such as electron collision dissociation and dissociative electron attachment. When these electron processes occur within a small distance above the wafer, the neutral species, radicals and excited molecules, generated from these processes take part in etching reactions impacting selectivity, ARDE and micro-loading. The introduction of finFET devices at 22 nm technology node at Intel marks the transition of planar devices to 3-dimensional devices, which add to the challenges to etch process in fabricating such devices. In the sub-32 nm technology node, Back-end-of-the-line made a change with the implementation of Trench First Metal Hard Mask (TFMHM) integration scheme, which has hence gained traction and become the preferred integration of low-k materials for BEOL. This integration scheme also enables Self-Aligned Via (SAV) patterning which prevents via CD growth and confines via by line trenches to better control via to line spacing. In addition to this, lack of scaling of 193 nm Lithography and non-availability of EUV based lithography beyond concept, has placed focus on novel multiple patterning schemes. This added complexity has resulted in multiple etch schemes to enable technology scaling below 80 nm Pitches, as shown by the memory manufacturers. Double-Patterning and Quad-Patterning have become increasingly used techniques to achieve 64 nm, 56 nm and 45 nm Pitch technologies in Back-end-of-the-line. Challenges associated in the plasma etching of these multiple integration schemes will be discussed in the presentation. In collaboration with A. Ranjan, TEL Technology Center, America

  18. Multichamber reactive ion etching processing for III-V optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Rothman, Mark A.; Thompson, John A.; Armiento, Craig A.

    1991-03-01

    A multistep reactive ion etching (RIE) process sequence has been developed for fabrication of optoelectronic devices in 111-V semiconductor materials. This process was developed in a multichamber RIlE system that has been adapted to use a different etch chemistry in each of the four chambers as well as robotic handling of small pieces of ITT-V materials. This system has been used to fabricate ridge waveguide lasers based on the TnPJTnGaAsP material system. The etch sequence consists of the following steps: SiNX patterning in an SF6 plasma photoresist removal in an plasma ridge formation in the InP and InGaAsP epitaxial layers using a CH4/H2/Ar plasma and polymer removal using an 0 2 plasma. Laser interferometry and emission spectroscopy techniques were used to establish endpoints for many of these process steps. Laser arrays with threshold currents as low as 22 mA have been routinely fabricated using this process.

  19. Sampling plan optimization for detection of lithography and etch CD process excursions

    NASA Astrophysics Data System (ADS)

    Elliott, Richard C.; Nurani, Raman K.; Lee, Sung Jin; Ortiz, Luis G.; Preil, Moshe E.; Shanthikumar, J. G.; Riley, Trina; Goodwin, Greg A.

    2000-06-01

    Effective sample planning requires a careful combination of statistical analysis and lithography engineering. In this paper, we present a complete sample planning methodology including baseline process characterization, determination of the dominant excursion mechanisms, and selection of sampling plans and control procedures to effectively detect the yield- limiting excursions with a minimum of added cost. We discuss the results of our novel method in identifying critical dimension (CD) process excursions and present several examples of poly gate Photo and Etch CD excursion signatures. Using these results in a Sample Planning model, we determine the optimal sample plan and statistical process control (SPC) chart metrics and limits for detecting these excursions. The key observations are that there are many different yield- limiting excursion signatures in photo and etch, and that a given photo excursion signature turns into a different excursion signature at etch with different yield and performance impact. In particular, field-to-field variance excursions are shown to have a significant impact on yield. We show how current sampling plan and monitoring schemes miss these excursions and suggest an improved procedure for effective detection of CD process excursions.

  20. Fabrication of suspended thermally insulating membranes using frontside micromachining of the Si substrate: characterization of the etching process

    NASA Astrophysics Data System (ADS)

    Tserepi, A.; Tsamis, C.; Kokkoris, G.; Gogolides, E.; Nassiopoulou, A. G.

    2003-03-01

    We describe a frontside Si micromachining process for the fabrication of suspended silicon oxide or nitride membranes for thermal sensors. Membrane release is achieved by means of lateral nearly isotropic dry etching of the bulk silicon substrate, the etching being optimized for high rates and high selectivity with respect to the photoresist used to protect the device and the membrane material. Lateral Si etch rates of the order of 6-7 mum min-1 have been achieved in a high-density F-based plasma, which permit a reasonable etching time for the release of the membrane and the simultaneous formation of the cavity underneath ensuring thermal isolation of the final device. The proposed process can enhance the flexibility of device design and reduce the complexity of the fabrication process, since it does not require any additional steps other than the photoresist lithography for the protection of the active elements (e.g. polysilicon heaters and catalytic materials) that are formed on top of the membrane, due to the high selectivity of the process for Si etching with respect to the photoresist. We attempt to explain the observed dependencies of etch rates and selectivities on the plasma parameters and the dimensions of the released membranes by means of a simulator of the mechanisms involved in etching of structures.

  1. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    PubMed

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise. PMID:25958585

  2. Award-Winning Etching Process Cuts Solar Cell Costs (Fact Sheet)

    SciTech Connect

    Not Available

    2013-08-01

    NREL scientists have invented the 'black silicon' nanocatalytic wet-chemical etch, an inexpensive, one-step process that literally turns the solar cells black, allowing them to absorb more than 98% of incident sunlight. The process costs just a few cents per watt of solar-cell power-producing capacity. Increases in manufactured cell efficiencies of up to 0.8% are possible because of the reduced reflectance of black silicon. This would reduce silicon solar module costs by $5-$10 per module.

  3. Integration and optimization of the DUV ALTA pattern generation system using a CAR process with the Tetra photomask etch system

    NASA Astrophysics Data System (ADS)

    Buxbaum, Alex H.; Fuller, Scott E.; Montgomery, Warren; Ungureit, Michael E.

    2003-12-01

    Etec Systems, the Mask Business Group of Applied Materials, is in a unique position within the mask making industry - Etec has the opportunity to integrate individual parts of the overall mask manufacturing process to provide a more complete solution. Here we present the integration of the DUV ALTA laser pattern generator and the TetraTM photomask etch system with advanced CAR resist processes. Dry etch process effects of flow, overetch, and oxygen content (in a Cl2/O2/He plasma) are discussed for the baseline POR resist in terms of etch rate, selectivity, etch bias, CD uniformity and micro-loading; the optimized etch process space was then implemented for advanced CAR resists. Iso-dense bias, football pattern loading and other pattern transfer results influencing mask manufactureability are also presented. Within the synthesis and optimization of the pattern generation system, process, and dry etch sub 13 nm range process uniformity has been achieved. The integrated ALTA / Tetra / Advanced-CAR solution set is characterized on both Etec test patterns and customer demonstrations.

  4. Nanotexturing process on microtextured surfaces of silicon solar cells by SF6/O2 reactive ion etching.

    PubMed

    Ji, Hyungyong; Choi, Jaeho; Lim, Gyoungho; Parida, Bhaskar; Kim, Keunjoo; Jo, Jung Hee; Kim, Hong Seub

    2013-12-01

    We investigated a nanotexturing process on the microtextured surface of single crystalline silicon solar cell by the reactive ion etching process in SF6/O2 mixed gas ambient. P-type Si wafer samples were prepared using a chemical wet etching process to address saw damage removal and achieve microtexturing. The microtextured wafers were further processed for nanotexturing by exposure to reactive ions within a circular tray of wafer carrier containing many small holes for uniform etching. As the dry etching times were increased to 2, 4 and finally to 8 min, surface structures were observed in a transition from nanoholes to nanorods, and a variation in wafer color from dark blue to black. The surface nanostructures showed a lowered photoreflectance and enhanced quantum efficiency within the visible light region with wavelengths of less than 679 nm. The nanohole structure etched for 2 min showed enhanced conversion efficiency when compared to the bare sample; however, the nanorod structure etched for 8 min exhibited the decreased efficiency with a reduced short circuit current, indicating that the surface nanostructural damage with the enlarged nanoperimetric surface area is sensitive to surface passivation from the surface recombination process.

  5. Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

    NASA Astrophysics Data System (ADS)

    Altamore, C.; Tringali, C.; Sparta', N.; Di Marco, S.; Grasso, A.; Ravesi, S.

    2010-02-01

    In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (105) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 101 Hz to 106 Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl2/Ar chemistry. The relationship between the etch rate and the Cl2/Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl2/Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

  6. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, Stephen M.; Tao, Hongyi; Todd-Copley, Judith A.

    1991-01-01

    A process for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength.

  7. Etching process for improving the strength of a laser-machined silicon-based ceramic article

    DOEpatents

    Copley, S.M.; Tao, H.; Todd-Copley, J.A.

    1991-06-11

    A process is disclosed for improving the strength of laser-machined articles formed of a silicon-based ceramic material such as silicon nitride, in which the laser-machined surface is immersed in an etching solution of hydrofluoric acid and nitric acid for a duration sufficient to remove substantially all of a silicon film residue on the surface but insufficient to allow the solution to unduly attack the grain boundaries of the underlying silicon nitride substrate. This effectively removes the silicon film as a source of cracks that otherwise could propagate downwardly into the silicon nitride substrate and significantly reduce its strength. 1 figure.

  8. Gallium arsenide surface chemistry and surface damage in a chlorine high density plasma etch process

    NASA Astrophysics Data System (ADS)

    Eddy, C. R., Jr.; Glembocki, O. J.; Leonhardt, D.; Shamamian, V. A.; Holm, R. T.; Thoms, B. D.; Butler, J. E.; Pang, S. W.

    1997-11-01

    In an effort to monitor ion-driven surface chemistry in the high density plasma etching of GaAs by Cl2/Ar plasma chemistries, we have applied mass spectrometry and careful substrate temperature control. Etch product chlorides were mass analyzed while the substrate temperature was monitored by optical bandgap thermometry and as pressure (neutral flux), microwave power (ion flux) and rf bias of the substrate (ion energy) were varied. By ensuring that the substrate temperature does not deviate during process variations, the changes in product mass peak intensities are a direct measure of changes in the ionassisted surface chemistry which promotes anisotropic etching. Experimental results show that ion-assisted surface chemistry is optimum when sufficient Cl and Cl+ are present in the incident plasma flux. These conditions are met at low coupled microwave powers (<300 W) and low total process pressures (<1.0 mTorr) for input gas mixtures of 25% Cl2 in Ar. Three mechanistic regions are identified for surface chemistry as a function of incident ion energy: 1) largely thermal chemistry for <50 eV; 2) ion-assisted chemistry for 50 200 eV; and 3) sputtering for >200 eV. Photoreflectance measurements of the surface Fermi level show significant damage for ion energies >75 eV. However, in situ and ex situ surface passivations can recover the surface Fermi level for up to 200 eV ion energies, in good correlation to the onset of sputtering and subsurface damage. Thus, anisotropic, low damage pattern transfer is possible for ion energies between 50 and 200 eV.

  9. Plasma etching processes for the integration of InP based compounds on 200mm Si wafer for photonic applications

    NASA Astrophysics Data System (ADS)

    Pargon, E.; Gay, G.; Petit-Etienne, C.; Brihoum, M.; Bizouerne, M.; Burtin, P.; Barnola, S.

    2016-03-01

    Ar/Cl2/CH4 gas mixture has been investigated for the development of plasma etching process dedicated to the patterning of 3μm-deep InP structures integrated on 200mm SiO2 carrier wafer. The plasma process requirements are: high InP etch rates (>500nm.min-1), high InP/SiO2 selectivity (<40), anisotropic profiles and smooth bottom and sidewalls surfaces. The process development mainly focuses on the impact of the gas ratio and gas flow on the etch rates, selectivity, pattern profile and surface roughness. It is demonstrated that the CH4 flow drives the process performance and that by adjusting it properly, a narrow process window provides acceptable selectivity of 25, anisotropic profiles and smooth surface. The difficulty of the process development using Ar/Cl2/CH4 gas mixture is to combine high InP/SiO2 selectivity and anisotropic profiles since to passivate efficiently the InP sidewalls and prevent from lateral etching, it seems that a SiOC like deposition is needed, which is only possible if the SiO2 wafer is etched.

  10. Pattern scaling with directed self assembly through lithography and etch process integration

    NASA Astrophysics Data System (ADS)

    Rathsack, Benjamen; Somervell, Mark; Hooge, Josh; Muramatsu, Makoto; Tanouchi, Keiji; Kitano, Takahiro; Nishimura, Eiichi; Yatsuda, Koichi; Nagahara, Seiji; Hiroyuki, Iwaki; Akai, Keiji; Hayakawa, Takashi

    2012-03-01

    Directed self-assembly (DSA) has the potential to extend scaling for both line/space and hole patterns. DSA has shown the capability for pitch reduction (multiplication), hole shrinks, CD self-healing as well as a pathway towards line edge roughness (LER) and pattern collapse improvement [1-4]. The current challenges for industry adoption are materials maturity, practical process integration, hardware capability, defect reduction and design integration. Tokyo Electron (TEL) has created close collaborations with customers, consortia and material suppliers to address these challenges with the long term goal of robust manufacturability. This paper provides a wide range of DSA demonstrations to accommodate different device applications. In collaboration with IMEC, directed line/space patterns at 12.5 and 14 nm HP are demonstrated with PS-b-PMMA (poly(styrene-b-methylmethacrylate)) using both chemo and grapho-epitaxy process flows. Pre-pattern exposure latitudes of >25% (max) have been demonstrated with 4X directed self-assembly on 300 mm wafers for both the lift off and etch guide chemo-epitaxy process flows. Within TEL's Technology Development Center (TDC), directed selfassembly processes have been applied to holes for both CD shrink and variation reduction. Using a PS-b-PMMA hole shrink process, negative tone developed pre-pattern holes are reduced to below 30 nm with critical dimension uniformity (CDU) of 0.9 nm (3s) and contact edge roughness (CER) of 0.8 nm. To generate higher resolution beyond a PS-b-PMMA system, a high chi material is used to demonstrate 9 nm HP line/ space post-etch patterns. In this paper, TEL presents process solutions for both line/space and hole DSA process integrations.

  11. Study on closed recycling regeneration process of FeCl3 waste etching solution and recovery of Copper

    NASA Astrophysics Data System (ADS)

    Miao, X. F.; Zhou, X. T.; Wang, R. X.; Zhai, D. H.; Ran, H. H.

    2016-08-01

    FeCl3 etching solution is widely used in etching processes due to its strong oxidation and corrosion properties. However, significant amounts of waste etching solution is produced, which pollutes the environment and wastes materials. Aiming to address problems related to the use of recycled FeCl3 waste etching solution containing Cu, the crystallization regeneration process in an enterprise was improved and the copper element was recovered in the form of copper chloride crystal. Based on the original process, a hydrocyclone was added to preseparate the slurry. By investigating the change of the inlet flow rate and separation efficiency of the hydrocyclone with inlet pressure under different concentrations, the optimal inlet pressure was determined to be approximately 0.25Mpa. Experimental results indicated that the workload of the centrifuge was reduced by approximately 80%, the average specific surface area of the copper chloride crystal was decreased by 50%, the production of copper chloride crystal byproducts after washing process was increased by approximately 20% and regeneration of FeCl3 waste etching solution was also realized.

  12. Novel ArF photoresist polymer to suppress the roughness formation in plasma etching processes

    NASA Astrophysics Data System (ADS)

    Kato, Keisuke; Yasuda, Atsushi; Maeda, Shin-ichi; Uesugi, Takuji; Okada, Takeru; Wada, Akira; Samukawa, Seiji

    2013-03-01

    The serious problem associated with 193-nm lithography using an ArF photoresist is roughness formation of photoresist polymer during plasma processes. We have previously investigated the mechanism of roughness formation caused by plasma. The main deciding factor for roughness formation is a chemical reaction between photoresist polymer and reactive species from plasma. The lactone group in photoresist polymer is highly chemically reactive, and shrinking the lactone structure enhances the roughness formation. In this paper, on the basis of the mechanism of roughness formation, we propose a novel ArF photoresist polymer. The roughness formation was much more suppressed in the novel photoresist polymer during plasma etching process than in the previous type. In the novel photoresist polymer, chemical reactions were spread evenly on the photoresist film surface by adding the polar structure. As a result, decreases in the lactone group were inhibited, leading to suppressing ArF photoresist roughness.

  13. Scalable shape-controlled fabrication of curved microstructures using a femtosecond laser wet-etching process.

    PubMed

    Bian, Hao; Yang, Qing; Chen, Feng; Liu, Hewei; Du, Guangqing; Deng, Zefang; Si, Jinhai; Yun, Feng; Hou, Xun

    2013-07-01

    Materials with curvilinear surface microstructures are highly desirable for micro-optical and biomedical devices. However, realization of such devices efficiently remains technically challenging. This paper demonstrates a facile and flexible method to fabricate curvilinear microstructures with controllable shapes and dimensions. The method composes of femtosecond laser exposures and chemical etching process with the hydrofluoric acid solutions. By fixed-point and step-in laser irradiations followed by the chemical treatments, concave microstructures with different profiles such as spherical, conical, bell-like and parabola were fabricated on silica glasses. The convex structures were replicated on polymers by the casting replication process. In this work, we used this technique to fabricate high-quality microlens arrays and high-aspect-ratio microwells which can be used in 3D cell culture. This approach offers several advantages such as high-efficient, scalable shape-controllable and easy manipulations.

  14. Process control of chrome dry etching by complete characterization of the RF power delivery

    NASA Astrophysics Data System (ADS)

    Sass, Björn; Schubert, Ralf; Jakubski, Thomas; Mauermann, Sebastian; Nesladek, Pavel; Wiswesser, Andreas; Gindra, Karl-Heinz; Malone, Ray

    2008-10-01

    In order to fulfil the upcoming requirements for photomasks there is a need for improving the process stability (reproducibility) of the unit processes in photomask fabrication. In order to understand and minimize the etch contribution to the CD stability impedance sensors integrated into the capacitively coupled radio frequency (RF) circuit (bias circuit) have shown a big potential. The last step towards a full characterization of the RF properties is the integration of impedance sensors in the inductively coupled RF circuit (source). This kind of sensor measures voltage, current and phase angle for the fundamental (13.56 MHz) and higher harmonics (up to the 5th harmonic). In this paper we are describing the integration of the Z-Scan sensors into the source RF matchbox and its impact on the RF and CD characteristics of the mask etcher. The central point is the correlation of impedance data to CD data. We will also compare the responses for bias and source impedance measurements.

  15. Alkaline etch system qualification

    SciTech Connect

    Goldammer, S.E.; Pemberton, S.E.; Tucker, D.R.

    1997-04-01

    Based on the data from this qualification activity, the Atotech etch system, even with minimum characterization, was capable of etching production printed circuit products as good as those from the Chemcut system. Further characterization of the Atotech system will improve its etching capability. In addition to the improved etch quality expected from further characterization, the Atotech etch system has additional features that help reduce waste and provide for better consistency in the etching process. The programmable logic controller and computer will allow operators to operate the system manually or from pre-established recipes. The evidence and capabilities of the Atotech system made it as good as or better than the Chemcut system for etching WR products. The Printed Wiring Board Engineering Department recommended that the Atotech system be released for production. In December 1995, the Atotech system was formerly qualified for production.

  16. Characterization of the NiFe sputter etch process in a rf plasma

    SciTech Connect

    Kropewnicki, Thomas J.; Paterson, Alex M.; Panagopoulos, Theodoros; Holland, John P.

    2006-05-15

    The sputter etching of NiFe thin films by Ar ions in a rf plasma has been studied and characterized with the use of a Langmuir probe. The NiFe sputter etch rate was found to depend strongly on incident ion energy, with the highest NiFe etch rates occurring at high rf bias power, low pressure, and moderate rf source power. NiFe etch rates initially increased with increasing rf source power, then saturated at higher rf source powers. Pressure had the weakest effect on NiFe etch rates. Empirically determined sputter yields based on the NiFe etch rates and ion current densities were calculated, and these compared favorably to sputter yields determined using the sputtering model proposed by Sigmund [Phys. Rev. 184, 383 (1969)].

  17. Si nanowires by a single-step metal-assisted chemical etching process on lithographically defined areas: formation kinetics

    PubMed Central

    2011-01-01

    In this paper, we investigate the formation kinetics of Si nanowires [SiNWs] on lithographically defined areas using a single-step metal-assisted chemical etching process in an aqueous HF/AgNO3 solution. We show that the etch rate of Si, and consequently, the SiNW length, is much higher on the lithographically defined areas compared with that on the non-patterned areas. A comparative study of the etch rate in the two cases under the same experimental conditions showed that this effect is much more pronounced at the beginning of the etching process. Moreover, it was found that in both cases, the nanowire formation rate is linear with temperature in the range from 20°C to 50°C, with almost the same activation energy, as obtained from an Arrhenius plot (0.37 eV in the case of non-patterned areas, while 0.38 eV in the case of lithographically patterned areas). The higher etch rate on lithographically defined areas is mainly attributed to Si surface modification during the photolithographic process. PACS: 68; 68.65-k. PMID:22087735

  18. High purity chemical etching and thermal passivation process for Ge(001) as nanostructure template.

    PubMed

    Blumenstein, Christian; Meyer, Sebastian; Ruff, Andreas; Schmid, Benjamin; Schäfer, Jörg; Claessen, Ralph

    2011-08-14

    An advanced two-step cleaning process of the Ge(001) surface for nanoscience requirements is presented. First, wet-chemical etching with a variant of the Piranha solution (H(2)SO(4), H(2)O(2), H(2)O) is used to remove contaminants as well as the native oxide layer. Second, passivation of the surface is achieved by a rapid thermal oxidation step, leading to a homogeneous protective oxide layer. The thickness of the oxide layer is tuned to be thick enough to protect the surface, yet thin enough to be completely removed by thermal treatment in ultra-high vacuum. The application of this recipe results in an outstandingly clean and atomically flat surface, with carbon contamination at the detection limit of x-ray photoelectron spectroscopy. Scanning tunneling microscopy and electron diffraction reveal a long range ordered surface with typical terrace diameters of ~100 nm, suitable for the growth of atomic-scale nanostructures.

  19. XAFS studies of monodisperse Au nanoclusters formation in the etching process

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Huang, Ting; Liu, Wei; Bao, Jie; Huang, Yuanyuan; Cao, Yuanjie; Yao, Tao; Sun, Zhihu; Wei, Shiqiang

    2016-05-01

    Understanding the formation mechanism of gold nanoclusters is essential to the development of their synthetic chemistry. Here, by using x-ray absorption fine-structure (XAFS) spectroscopy, UV-Vis and MS spectra, the formation process of monodisperse Au13 nanoclusters is investigated. We find that a critical step involving the formation of smaller Au8-Au11 metastable intermediate clusters induced by the HCl + HSR etching of the polydisperse Aun precursor clusters occurs firstly. Then these intermediate species undergo a size-growth to Au13 cores, followed by a slow structure rearrangement to reach the final stable structure. This work enriches the understanding of cluster formation chemistry and may guide the way towards the design and the controllable synthesis of nanoclusters.

  20. Probe microloading effect of in-situ etch in EPROM stack-gate process

    NASA Astrophysics Data System (ADS)

    Chiou, Jang Ming; Pan, Sheng Liang; Ching, Kai Ming; Chang, Bi-Jiang; Lu, Kuo-Liang

    1998-08-01

    An unpredictable significant microloading effect occurs between array and low photoresist ratio area when C2F6Cl2 and HBr are used as etch gas to define EPROM stack gate. Although we have examined etch time for array is enough, much poly residue still exist on those test keys with low photoresist ratio areas that lead to failure of electric parameter. On array area, polymer formed from C2F6 reactant gas trends to accumulate upon side-wall. Oppositely on the low photoresist area, there is almost not nay side-wall that can offer the medium absorbed by polymer. It will fall down and deposits upon poly surface. That will be a barrier. In the beginning, sufficient etch time often result from under- etch issue. We have modified etch time to get best optimal condition. Now, this issue does not occur any more.

  1. Electromigration study of copper lines on steps prepared by a plasma-based etch process

    SciTech Connect

    Lin, Chi-Chou; Kuo Yue

    2012-03-15

    The electromigration phenomenon of the copper line etched with a plasma-based process over the SiN{sub x} step has been investigated. Two important factors, i.e., the dielectric topography and the stress temperature, were examined using the accelerated isothermal electromigration method. The activation energy of 0.73 eV to 0.89 eV indicates two possible mass transport pathways: interfacial and copper surface diffusions. The copper line on the SiN{sub x} step has a shorter lifetime and a smaller activation energy than the copper line on the flat surface has. For the former, voids were formed at the cusp region and perpendicular to the current flow direction. For the latter, voids were formed in series and parallel to the current flow direction. The ''neck'' structure at the cusp region, which is a result of the inappropriate etching condition, further decreased the lifetime and the activation energy. The lifetime of the ''neck-free'' copper line over the SiN{sub x} step was estimated to be 7.1 x 10{sup 9} s under the high-speed IC operation condition. The thermal stress mismatch between the copper layer and TiW barrier layer as well as the underneath dielectric layer facilitated the void formation. The step effect on the lifetime was reduced when the test temperature was high because of the change of the local stress. In summary, the topography and the test temperature are critical factors for the copper line's lifetime.

  2. Charge-free method of forming nanostructures on a substrate

    DOEpatents

    Hoffbauer; Mark , Akhadov; Elshan

    2010-07-20

    A charge-free method of forming a nanostructure at low temperatures on a substrate. A substrate that is reactive with one of atomic oxygen and nitrogen is provided. A flux of neutral atoms of least one of oxygen and nitrogen is generated within a laser-sustained-discharge plasma source and a collimated beam of energetic neutral atoms and molecules is directed from the plasma source onto a surface of the substrate to form the nanostructure. The energetic neutral atoms and molecules in the beam have an average kinetic energy in a range from about 1 eV to about 5 eV.

  3. A facile processing way of silica needle arrays with tunable orientation by tube arrays fabrication and etching method

    SciTech Connect

    Zhu Mingwei; Gao Haigen; Li Hongwei; Xu Jiao; Chen Yanfeng

    2010-03-15

    A simple method to fabricate silica micro/nano-needle arrays (SNAs) is presented based on tube-etching mechanism. Using silica fibers as templates, highly aligned and free-standing needle arrays are created over large area by simple processes of polymer infiltration, cutting, chemical etching and polymer removal. Their sizes and orientations can be arbitrarily and precisely tuned by simply selecting fiber sizes and the cutting directions, respectively. This technique enables the needle arrays with special morphology to be fabricated in a greatly facile way, thereby offers them the potentials in various applications, such as optic, energy harvesting, sensors, etc. As a demonstration, the super hydrophobic property of PDMS treated SNAs is examined. - Graphical abstract: Silica needle arrays are fabricated by tube arrays fabrication and etching method. They show super hydrophobic property after being treated with PDMS.

  4. The etching process of boron nitride by alkali and alkaline earth fluorides under high pressure and high temperature

    SciTech Connect

    Guo, W.; Ma, H.A.; Jia, X.

    2014-03-01

    Graphical abstract: - Highlights: • Appropriate etch processes of hBN and cBN under HPHT are proposed. • The degree of the crystallization of hBN was decreased. • A special cBN growth mechanism with a triangular unit is proposed. • Plate-shape cBN crystals with large ratio of length to thickness were obtained. • A strategy provides useful guidance for controlling the cBN morphology. - Abstract: Some new etching processes of hexagonal boron nitride (hBN) and cubic boron nitride (cBN) under high pressure and high temperature in the presence of alkali and alkaline earth fluorides have been discussed. It is found that hBN is etched distinctly by alkali and alkaline earth fluorides and the morphology of hBN is significantly changed from plate-shape to spherical-shape. Based on the “graphitization index” values of hBN, the degree of the crystallization of hBN under high pressure and high temperature decreases in the sequence of LiF > CaF{sub 2} > MgF{sub 2}. This facilitates the formation of high-quality cBN single crystals. Different etch steps, pits, and islands are observed on cBN surface, showing the strong etching by alkali and alkaline earth fluorides and the tendency of layer-by-layer growth. A special layer growth mechanism of cBN with a triangular unit has been found. Furthermore, the morphologies of cBN crystals are apparently affected by a preferential surface etching of LiF, CaF{sub 2} and MgF{sub 2}. Respectively, the plate-shape and tetrahedral cBN crystals can be obtained in the presence of different alkali and alkaline earth fluorides.

  5. Efficient process development for bulk silicon etching using cellular automata simulation techniques

    NASA Astrophysics Data System (ADS)

    Marchetti, James; He, Yie; Than, Olaf; Akkaraju, Sandeep

    1998-09-01

    This paper describes cellular automata simulation techniques used to predict the anisotropic etching of single-crystal silicon. In particular, this paper will focus on the application of wet etching of silicon wafers using typical anisotropic etchants such as KOH, TMAH, and EDP. Achieving a desired final 3D geometry of etch silicon wafers often is difficult without requiring a number of fabrication design iterations. The result is wasted time and resources. AnisE, a tool to simulate anisotropic etching of silicon wafers using cellular automata simulation, was developed in order to efficiently prototype and manufacture MEMS devices. AnisE has been shown to effectively decrease device development time and costs by up to 50% and 60%, respectively.

  6. Award-Winning Etching Process Cuts Solar Cell Costs (Revised) (Fact Sheet)

    SciTech Connect

    Not Available

    2011-05-01

    The NREL "black silicon" nanocatalytic wet-chemical etch is an inexpensive, one-step method to minimize reflections from crystalline silicon solar cells. The technology enables high-efficiency solar cells without the use of expensive antireflection coatings.

  7. Simulation of microwave pulsing in a radial line slot antenna etch process reactor

    NASA Astrophysics Data System (ADS)

    Upadhyay, Rochan; Ishibashi, Kiyotaka; Raja, Laxminarayan

    2013-09-01

    The radial line slot antenna reactor couples the microwave power to a process plasma through a slot antenna. This arrangement leads to efficient generation of plasma with high electron energy adjacent to the window and a lower energy near wafer surfaces. This arrangement is beneficial for low ion energy applications such as soft etching or thin film processing. With increased charge densities, charge-up damage of dielectric surfaces can be a problem that can be addressed though plasma pulsing strategies in electronegative feed gases. The periodic power-off cycle results in an afterglow where electron attachment forms large amounts of negative ions that when extracted to the wafer surface, reduces the effects of positive charge trapping on the surface. We use computational modeling to investigate the effect of microwave pulsing on the negative ion generation rates for high density HBr and CF4 plasmas. We discuss improvements to a plasma chemistry mechanism for the pulsed plasma regime. Our results verify much larger negative ion to electron density ratios compared to the continuous (un-pulsed) case for both HBr and CF4 gases. Results also indicate greater plasma uniformity due to diffusion of positive and negative ions during the power-off phase of the pulse.

  8. Investigations on diamond nanostructuring of different morphologies by the reactive-ion etching process and their potential applications.

    PubMed

    Kunuku, Srinivasu; Sankaran, Kamatchi Jothiramalingam; Tsai, Cheng-Yen; Chang, Wen-Hao; Tai, Nyan-Hwa; Leou, Keh-Chyang; Lin, I-Nan

    2013-08-14

    We report the systematic studies on the fabrication of aligned, uniform, and highly dense diamond nanostructures from diamond films of various granular structures. Self-assembled Au nanodots are used as a mask in the self-biased reactive-ion etching (RIE) process, using an O2/CF4 process plasma. The morphology of diamond nanostructures is a close function of the initial phase composition of diamond. Cone-shaped and tip-shaped diamond nanostructures result for microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films, whereas pillarlike and grasslike diamond nanostructures are obtained for Ar-plasma-based and N2-plasma-based ultrananocrystalline diamond (UNCD) films, respectively. While the nitrogen-incorporated UNCD (N-UNCD) nanograss shows the most-superior electron-field-emission properties, the NCD nanotips exhibit the best photoluminescence properties, viz, different applications need different morphology of diamond nanostructures to optimize the respective characteristics. The optimum diamond nanostructure can be achieved by proper choice of granular structure of the initial diamond film. The etching mechanism is explained by in situ observation of optical emission spectrum of RIE plasma. The preferential etching of sp(2)-bonded carbon contained in the diamond films is the prime factor, which forms the unique diamond nanostructures from each type of diamond films. However, the excited oxygen atoms (O*) are the main etching species of diamond film.

  9. Quantum cascade laser based monitoring of CF{sub 2} radical concentration as a diagnostic tool of dielectric etching plasma processes

    SciTech Connect

    Hübner, M.; Lang, N.; Röpcke, J.; Helden, J. H. van; Zimmermann, S.; Schulz, S. E.; Buchholtz, W.

    2015-01-19

    Dielectric etching plasma processes for modern interlevel dielectrics become more and more complex by the introduction of new ultra low-k dielectrics. One challenge is the minimization of sidewall damage, while etching ultra low-k porous SiCOH by fluorocarbon plasmas. The optimization of this process requires a deeper understanding of the concentration of the CF{sub 2} radical, which acts as precursor in the polymerization of the etch sample surfaces. In an industrial dielectric etching plasma reactor, the CF{sub 2} radical was measured in situ using a continuous wave quantum cascade laser (cw-QCL) around 1106.2 cm{sup −1}. We measured Doppler-resolved ro-vibrational absorption lines and determined absolute densities using transitions in the ν{sub 3} fundamental band of CF{sub 2} with the aid of an improved simulation of the line strengths. We found that the CF{sub 2} radical concentration during the etching plasma process directly correlates to the layer structure of the etched wafer. Hence, this correlation can serve as a diagnostic tool of dielectric etching plasma processes. Applying QCL based absorption spectroscopy opens up the way for advanced process monitoring and etching controlling in semiconductor manufacturing.

  10. Integrated micromachined thermopile IR detectors with an XeF2 dry-etching process

    NASA Astrophysics Data System (ADS)

    Xu, Dehui; Xiong, Bin; Wang, Yuelin; Liu, Mifeng; Li, Tie

    2009-12-01

    Based on the Seebeck effect, the CMOS compatible micromachined thermopile is widely used in infrared detection for its advantages of low-cost, high batch yield, broad spectral response and insensitivity to ambient temperature. We present two integrated thermopile IR detectors on stacked dielectric layers realized by a standard P-well CMOS technology, followed by one CMOS compatible maskless XeF2 isotropic dry-etching step. Characterizations of CMOS devices, before and after XeF2 etching, respectively, were performed to investigate the effects of XeF2 etching on the CMOS devices. With a 2.5 µm thick stacked silicon oxide-nitride-oxide layer as an absorber, the rectangular thermopile detector and the circular thermopile detector provided responsivity of 14.14 and 10.26 V W-1, specific detectivity of 4.15 × 107 and 4.54 × 107 cm Hz1/2 W-1, and time constant of 23.7 and 14.6 ms, respectively. Compared with the rectangular thermopile detector, the circular thermopile detector is mechanically more stable, because its circular structure design eases the internal stress problem in the CMOS layers. After XeF2 etching, the maximum changes of threshold voltage, maximum transconductance and switching threshold voltage were 0.97%, 1.25% and 0.08%, respectively. Experimental results show that the effects of XeF2 etching on the CMOS devices are insignificant, and XeF2 etching is suitable for post-CMOS micromachining.

  11. Charging-free electrochemical system for harvesting low-grade thermal energy

    PubMed Central

    Yang, Yuan; Lee, Seok Woo; Ghasemi, Hadi; Loomis, James; Li, Xiaobo; Kraemer, Daniel; Zheng, Guangyuan; Cui, Yi; Chen, Gang

    2014-01-01

    Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)63−/4− redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas. PMID:25404325

  12. Charging-free electrochemical system for harvesting low-grade thermal energy.

    PubMed

    Yang, Yuan; Lee, Seok Woo; Ghasemi, Hadi; Loomis, James; Li, Xiaobo; Kraemer, Daniel; Zheng, Guangyuan; Cui, Yi; Chen, Gang

    2014-12-01

    Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)6(3-/4-) redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas.

  13. Chemical downstream etching of tungsten

    SciTech Connect

    Blain, M.G.; Jarecki, R.L.; Simonson, R.J.

    1998-07-01

    The downstream etching of tungsten and tungsten oxide has been investigated. Etching of chemical vapor deposited tungsten and e-beam deposited tungsten oxide samples was performed using atomic fluorine generated by a microwave discharge of argon and NF{sub 3}. Etching was found to be highly activated with activation energies approximated to be 6.0{plus_minus}0.5thinspkcal/mol and 5.4{plus_minus}0.4thinspkcal/mol for W and WO{sub 3}, respectively. In the case of F etching of tungsten, the addition of undischarged nitric oxide (NO) directly into the reaction chamber results in the competing effects of catalytic etch rate enhancement and the formation of a nearly stoichiometric WO{sub 3} passivating tungsten oxide film, which ultimately stops the etching process. For F etching of tungsten oxide, the introduction of downstream NO reduces the etch rate. {copyright} {ital 1998 American Vacuum Society.}

  14. Etching and Growth of GaAs

    NASA Technical Reports Server (NTRS)

    Seabaugh, A. C.; Mattauch, R., J.

    1983-01-01

    In-place process for etching and growth of gallium arsenide calls for presaturation of etch and growth melts by arsenic source crystal. Procedure allows precise control of thickness of etch and newly grown layer on substrate. Etching and deposition setup is expected to simplify processing and improve characteristics of gallium arsenide lasers, high-frequency amplifiers, and advanced integrated circuits.

  15. Self-aligned maskless process for etching cavities in SOI wafers to enhance the quality factor of MEMS resonators

    NASA Astrophysics Data System (ADS)

    Mohammad, Wajihuddin; Kaajakari, Ville

    2010-02-01

    We present a low cost, self-aligned, process to etch cavities under movable structures in commercially available SOI wafers. The cavity is formed by electrochemically etching the substrate through the openings in the SOI structural layer. A tuning fork structure fabricated with the cavity SOI process has resonant frequency of 247 kHz and the measured intrinsic is Q = 82,000 at 35 mTorr. Comparing the measured quality factor as function of pressure for devices with and without the cavity, the devices with cavity showed a consistent improvement in the quality factor by a factor of 2-3 except for very low pressures where the intrinsic mechanical quality factor dominates. As the distance between the device and substrate is increased from 2 μm (buried oxide thickness) to 10 μm (electrochemically etched cavity), the parasitic capacitance to the substrate is also reduced by 5x. In addition, the stiction between the device and substrate is effectively eliminated.

  16. Feedback control of HfO{sub 2} etch processing in inductively coupled Cl{sub 2}/N{sub 2}/Ar plasmas

    SciTech Connect

    Lin Chaung; Leou, K.-C.; Li, T.-C.; Lee, L.-S.; Tzeng, P.-J.

    2008-09-15

    The etch rate of HfO{sub 2} etch processing has been feedback controlled in inductively coupled Cl{sub 2}/N{sub 2}/Ar plasmas. The ion current and the root mean square rf voltage on the wafer stage, which are measured using a commercial impedance meter connected to the wafer stage, are chosen as controlled variables because the positive-ion flux and ion energy incident upon the wafer surface are the key factors that determine the etch rate. Two 13.56 MHz rf generators are used to adjust the inductively coupled plasma power and bias power which control ion density and ion energy, respectively. The adopted HfO{sub 2} etch processing used rather low rf voltage. The ion-current value obtained by the power/voltage method is underestimated, so the neural-network model was developed to assist estimating the correct ion-current value. The experimental results show that the etch-rate variation of the closed-loop control is smaller than that of the open-loop control. However, the first wafer effect cannot be eliminated using closed-loop control and thus to achieve a constant etch rate, the chamber-conditioning procedure is required in this etch processing.

  17. Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Hong, Hyun Seon; Cho, Sung-Soo

    2016-05-01

    Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m(3) of copper and 1.35kg/m(3) of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process. PMID:26918838

  18. Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes.

    PubMed

    Swain, Basudev; Mishra, Chinmayee; Hong, Hyun Seon; Cho, Sung-Soo

    2016-05-01

    Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m(3) of copper and 1.35kg/m(3) of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100-500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process.

  19. Plasma surface interactions in nanoscale processing: Preservation of low-k integrity and high-k gate-stack etching with silicon selectivity

    NASA Astrophysics Data System (ADS)

    Shoeb, Juline

    Plasma-surface interactions are very important in the fabrication of the nm-sized features of integrated circuits. Plasma processes are employed to produce high-resolution patterns in many of the thin layers of silicon integrated circuits and to remove masking layers while maintaining high selectivity. Integrated plasma processes consisting of sequential steps such as etch, clean and surface modification, are used in semiconductor industries. The surface in contact with the process plasma is exposed to the fluxes of neutrals, ions, molecules, electrons and photons. Modeling of surface reaction mechanisms requires the determination of the characterizations of fluxes (e.g. composition, magnitude, energy and angle) and development of the reaction mechanisms of the processes such as adsorption, reflection, bond breaking and etch product evolution, while reproducing the experimental results. When modeling the reaction mechanism for an entirely new material, the experimental data is often fragmentary. Therefore, fundamental principles such as bond energies and volatility of the etch products must be considered to develop the mechanism. In this thesis, results from a computational investigation of porous low-k SiCOH etching in fluorocarbon plasmas, damage during cleaning of CFx polymer etch residue in Ar/O2 and He/H2 plasmas, NH3 plasma pore sealing and low-k degradation due to water uptake, will be discussed. The plasma etching of HfO2 gate-stacks is also computationally investigated with an emphasis on the selectivity between HfO2 and Si.

  20. Agile dry etching of compound semiconductors for science-based manufacturing using in-situ process control

    SciTech Connect

    ASHBY,CAROL I.; VAWTER,GREGORY A.; BREILAND,WILLIAM G.; BRUSKAS,LARRY A.; WOODWORTH,JOSEPH R.; HEBNER,GREGORY A.

    2000-02-01

    In-situ optical diagnostics and ion beam diagnostics for plasma-etch and reactive-ion-beam etch (RIBE) tools have been developed and implemented on etch tools in the Compound Semiconductor Research Laboratory (CSRL). The optical diagnostics provide real-time end-point detection during plasma etching of complex thin-film layered structures that require precision etching to stop on a particular layer in the structure. The Monoetch real-time display and analysis program developed with this LDRD displays raw and filtered reflectance signals that enable an etch system operator to stop an etch at the desired depth within the desired layer. The ion beam diagnostics developed with this LDRD will permit routine analysis of critical ion-beam profile characteristics that determine etch uniformity and reproducibility on the RIBE tool.

  1. Direct observations of freeze-etching processes of ice-embedded biomembranes by atomic force microscopy.

    PubMed

    Yamamoto, Daisuke; Tani, Koji; Gotoh, Toshiaki; Kouyama, Tsutomu

    2003-01-01

    We have fabricated a cryogenic atomic force microscope that is designed for structural investigation of freeze-fractured biological specimens. The apparatus is operated in liquid nitrogen gas at atmospheric pressure. Freeze-fracturing, freeze-etching and subsequent imaging are carried out in the same chamber, so that the surface topography of a fractured plane is easily visualized without ice contamination. A controlled superficial sublimation of volatile molecules allows us to obtain three-dimensional views of ultrastructures of biological membranes. PMID:12694853

  2. Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

    NASA Astrophysics Data System (ADS)

    Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Zdorovets, Maxim V.; Taltenov, Abzal A.

    2015-12-01

    In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H2O2 under UV irradiation (H2O2/UV) and Fenton system under visible light (Fenton/H2O2/Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H2O2/UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H2O2/Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

  3. From ‘petal effect’ to ‘lotus effect’ on the highly flexible Silastic S elastomer microstructured using a fluorine based reactive ion etching process

    NASA Astrophysics Data System (ADS)

    Frankiewicz, Christophe; Zoueshtiagh, Farzam; Talbi, Abdelkrim; Streque, Jérémy; Pernod, Philippe; Merlen, Alain

    2014-11-01

    A fluorine-based reactive ion etching (RIE) process has been applied on a new family of silicone elastomers named ‘Silastic S’ for the first time. Excellent mechanical properties are the principal advantage of this elastomer. The main objective of this study was (i) to develop a new process with an electrodeposited thin Nickel (Ni) layer as a mask to obtain a more precise pattern transfer for deep etching (ii) to investigate the etch rates and the etch profiles obtained under various plasma conditions (gas mixture ratios and pressure). The resulting process exhibits etch rates that range from 20 µm h-1 to 40 µm h-1. The process was optimized to obtain anisotropic profiles of the edges. Finally, it is shown that (iii) the wetting contact angle could be easily modified with this process from 103° to 162°, with a hysteresis that ranges from 2° to 140°. The process is, at present, the only reported solution to reproduce the ‘petal effect’ (high contact angle hysteresis value) on a highly flexible substrate. A possibility to control the contact angle hysteresis from the ‘petal effect’ to the ‘lotus effect’ (low contact angle hysteresis value) has been investigated to allow a precise control on the required energy to pin or unpin the contact line of water droplets. This opens multiple possibilities to exploit this elastomer in many microfluidics applications.

  4. Use of silane-based primer on silicon wafers to enhance adhesion of edge-protective coatings during wet etching: application of the TALON Wrap process

    NASA Astrophysics Data System (ADS)

    Dalvi-Malhotra, J.; Brand, G. J.; Zhong, X.-F.

    2007-02-01

    Hydrolyzed silane primer solutions were made of an organosilane in glycolether diluted with a large amount of water with or without an acid as a catalyst. The newly developed primer compositions exhibited an extended shelf life of 3 months or more. The compositions were specially designed to accommodate ProTEK TM. layer adhesion in the TALON Wrap. process. In this application, a spin-coatable polymeric material, ProTEK TM., is applied as the protective coating to coat the top, edge, and underside rim of the wafer in preparation for backside etching. By applying an underlayer of primer and an overlayer of ProTEK TM. coating to the top, edge and the bottom side rim of the wafer, an effective encapsulation of the wafer was achieved by using a custom-designed baffle. Each layer was applied by spin coating followed by baking at a wide temperature range. Thermal processing was followed by wet etching in KOH at an elevated temperature for . 10 hr. Post-etched wafers were rinsed with deionized (DI) water. Excellent edge profiles without "knife-edges" were obtained after etching the unprotected areas of the wafer. The process is fully automated because it is carried out in the TALON TM automated wafer-processing tool. Intact films with no lifting or peeling were obtained during or after the KOH etch process/DI rinse for silicon substrates.

  5. Cross-Sectional Conductive Atomic Force Microscopy of CdTe/CdS Solar Cells: Effects of Etching and Back-Contact Processes; Preprint

    SciTech Connect

    Moutinho, H. R.; Dhere, R. G.; Jiang, C.-S.; Gessert, T. A.; Duda, A. M.; Young, M.; Metzger, W. K.; Li, X.; Al-Jassim, M. M.

    2006-05-01

    We investigated the effects of the etching processes using bromine and nitric-phosphoric acid solutions, as well as of Cu, in the bulk electrical conductivity of CdTe/CdS solar cells using conductive atomic force microscopy (C-AFM). Although the etching process can create a conductive layer on the surface of the CdTe, the layer is very shallow. In contrast, the addition of a thin layer of Cu to the surface creates a conductive layer inside the CdTe that is not uniform in depth, is concentrated at grains boundaries, and may short circuit the device if the CdTe is too thin. The etching process facilitates the Cu diffusion and results in thicker conductive layers. The existence of this inhomogeneous conductive layer directly affects the current transport and is probably the reason for needing thick CdTe in these devices.

  6. Damage-free top-down processes for fabricating two-dimensional arrays of 7 nm GaAs nanodiscs using bio-templates and neutral beam etching.

    PubMed

    Wang, Xuan-Yu; Huang, Chi-Hsien; Tsukamoto, Rikako; Mortemousque, Pierre-Andre; Itoh, Kohei M; Ohno, Yuzo; Samukawa, Seiji

    2011-09-01

    The first damage-free top-down fabrication processes for a two-dimensional array of 7 nm GaAs nanodiscs was developed by using ferritin (a protein which includes a 7 nm diameter iron core) bio-templates and neutral beam etching. The photoluminescence of GaAs etched with a neutral beam clearly revealed that the processes could accomplish defect-free etching for GaAs. In the bio-template process, to remove the ferritin protein shell without thermal damage to the GaAs, we firstly developed an oxygen-radical treatment method with a low temperature of 280 °C. Then, the neutral beam etched the defect-free nanodisc structure of the GaAs using the iron core as an etching mask. As a result, a two-dimensional array of GaAs quantum dots with a diameter of ∼ 7 nm, a height of ∼ 10 nm, a high taper angle of 88° and a quantum dot density of more than 7 × 10(11) cm(-2) was successfully fabricated without causing any damage to the GaAs.

  7. Enhancement on photocatalytic activity of an amorphous titanium oxide film with nano-textured surface by selective-fluorination etching process

    SciTech Connect

    Shih, Pin-Chun; Huang, Cheng-Hao; Chen, Tai-Hong; Lai, Li-Wen; Lu, Yi-Shan; Liu, Day-Shan

    2014-04-01

    Highlights: • The amorphous TiO{sub x} film surface was modified via selective fluorination etching process. • The resulting nano-textured surface markedly enriched the specific surface area and surface acidity. • The photocatalytic activity was comparable to an annealed TiO{sub x} film with anatase structure. - Abstract: A selective-fluorination etching process achieved by an UV light pre-irradiation and the subsequently fluorination etching was developed to enhance the photocatalytic activity of a low-temperature deposited amorphous titanium oxide (a-TiO{sub x}) film. Textured surface on the a-TiO{sub x} films formed by this process were investigated using atomic force microscope and field emission scanning electron microscope. Evidence of the fluorine ions introduced into the a-TiO{sub x} films was examined using Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. The etching thickness of the a-TiO{sub x} film was found to be deeply relevant to the film pre-irradiated by the UV light. An a-TiO{sub x} film with nano-textured surface, which was favorable to enlarge the specific surface area, thus was obtainable from the notable etching selectivity of the film pre-irradiated by UV light through a nano-sized mask. In addition, the surface acidity of the a-TiO{sub x} film was enhanced by the formation of the Ti-F chemical bonds originating from the fluorination etching process, which also was functional to facilitate the production of surface OH free radicals. Accordingly, the resulting fluorinated a-TiO{sub x} film with nano-textured surface performed a quality photocatalytic activity comparable to that of the high-temperature achieved TiO{sub x} film with anatase structures.

  8. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  9. Submicron patterned metal hole etching

    DOEpatents

    McCarthy, Anthony M.; Contolini, Robert J.; Liberman, Vladimir; Morse, Jeffrey

    2000-01-01

    A wet chemical process for etching submicron patterned holes in thin metal layers using electrochemical etching with the aid of a wetting agent. In this process, the processed wafer to be etched is immersed in a wetting agent, such as methanol, for a few seconds prior to inserting the processed wafer into an electrochemical etching setup, with the wafer maintained horizontal during transfer to maintain a film of methanol covering the patterned areas. The electrochemical etching setup includes a tube which seals the edges of the wafer preventing loss of the methanol. An electrolyte composed of 4:1 water: sulfuric is poured into the tube and the electrolyte replaces the wetting agent in the patterned holes. A working electrode is attached to a metal layer of the wafer, with reference and counter electrodes inserted in the electrolyte with all electrodes connected to a potentiostat. A single pulse on the counter electrode, such as a 100 ms pulse at +10.2 volts, is used to excite the electrochemical circuit and perform the etch. The process produces uniform etching of the patterned holes in the metal layers, such as chromium and molybdenum of the wafer without adversely effecting the patterned mask.

  10. High-etch-rate bottom-antireflective coating and gap-fill materials using dextrin derivatives in via first dual-Damascene lithography process

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi; Sakaida, Yasushi; Shinjo, Tetsuya; Hashimoto, Keisuke; Nakajima, Yasuyuki

    2008-03-01

    The present paper describes a novel class of bottom antireflective coating (BARC) and gap fill materials using dextrin derivatives. The general trend of interconnect fabrication for such a high performance LSI is to apply cupper (Cu)/ low-dielectric-constant (low-k) interconnect to reduce RC delay. A via-first dual damascene process is one of the most promising processes to fabricate Cu/ low-k interconnect due to its wide miss-alignment margin. The sacrificial materials containing dextrin derivatives under resist for lithography were developed in via-first dual damascene process. The dextrin derivatives in this study was obtained by the esterification of the hydroxyl groups of dextrin resulting in improved solubility in the resist solvents such as propylene glycol monomethylether, propylene glycol monomethylether acetate, and ethyl lactate due to avoid the issue of defects that were caused by incompatability. The etch rate of our developed BARC and gap fill materials using dextrin derivatives was more than two times faster than one of the ArF resists evaluated in a CF4 gas condition using reactive ion etching. The improved etch performance was also verified by comparison with poly(hydroxystyrene), acrylate-type materials and latest low-k materials as a reference. In addition to superior etch performance, these materials showed good resist profiles and via filling performance without voids in via holes.

  11. Influence of etching processes on electronic transport in mesoscopic InAs/GaSb quantum well devices

    SciTech Connect

    Pal, Atindra Nath; Müller, Susanne; Ihn, Thomas; Ensslin, Klaus; Tschirky, Thomas; Charpentier, Christophe; Wegscheider, Werner

    2015-07-15

    We report the electronic characterization of mesoscopic Hall bar devices fabricated from coupled InAs/GaSb quantum wells sandwiched between AlSb barriers, an emerging candidate for two-dimensional topological insulators. The electronic width of the etched structures was determined from the low field magneto-resistance peak, a characteristic signature of partially diffusive boundary scattering in the ballistic limit. In case of dry-etching the electronic width was found to decrease with electron density. In contrast, for wet etched devices it stayed constant with density. Moreover, the boundary scattering was found to be more specular for wet-etched devices, which may be relevant for studying topological edge states.

  12. Experimental optimization of an anisotropic etching process for random texturization of silicon solar cells

    SciTech Connect

    King, D.L.; Buck, M.E.

    1991-01-01

    A multifactor experimental investigation of silicon surface texturing was conducted in Sandia's Photovoltaic Device Fabrication Laboratory using aqueous potassium-hydroxide (KOH) solutions with isopropyl alcohol (IPA) added as a complexing agent. Czochralski, magnetic-Czochralski, and float-zone silicon wafers of different resistivities with both polished and lapped surfaces were included in the experiment. Process variables considered were solution temperature, time in solution, degree of mechanical mixing, KOH concentration, and IPA concentration. Using hemispherical reflectance as the primary gauge of success, process variables were identified that resulted in an effective surface texture with reflectance less than 12% prior to anti-reflection coating. Of particular interest was a low temperature (70 {degrees}C) process with less than 2% concentration of both KOH and IPA and wide process variable tolerances. 6 refs., 6 figs., 1 tab.

  13. Cryogenic electron beam induced chemical etching.

    PubMed

    Martin, Aiden A; Toth, Milos

    2014-11-12

    Cryogenic cooling is used to enable efficient, gas-mediated electron beam induced etching (EBIE) in cases where the etch rate is negligible at room and elevated substrate temperatures. The process is demonstrated using nitrogen trifluoride (NF3) as the etch precursor, and Si, SiO2, SiC, and Si3N4 as the materials volatilized by an electron beam. Cryogenic cooling broadens the range of precursors that can be used for EBIE, and enables high-resolution, deterministic etching of materials that are volatilized spontaneously by conventional etch precursors as demonstrated here by NF3 and XeF2 EBIE of silicon. PMID:25333843

  14. Method for anisotropic etching in the manufacture of semiconductor devices

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor); Cross, Jon B. (Inventor)

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by hyperthermal atomic oxygen beams (translational energies of 0.2 to 20 eV, preferably 1 to 10 eV). Etching with hyperthermal oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask protected areas.

  15. Method for anisotropic etching in the manufacture of semiconductor devices

    DOEpatents

    Koontz, Steven L.; Cross, Jon B.

    1993-01-01

    Hydrocarbon polymer coatings used in microelectronic manufacturing processes are anisotropically etched by atomic oxygen beams (translational energies of 0.2-20 eV, preferably 1-10 eV). Etching with hyperthermal (kinetic energy>1 eV) oxygen atom species obtains highly anisotropic etching with sharp boundaries between etched and mask-protected areas.

  16. Improvement of Specimen Preparation Process for Bulge Test Using the Combination of XeF2 and Deep Reactive Ion Etching

    NASA Astrophysics Data System (ADS)

    Wu, Chung-Lin; Yip, Ming-Chuen; Fang, Weileun

    2009-06-01

    The bulge test is a convenient approach to determine the thin film mechanical properties. This study presents a fabrication process to prepare the circular membrane made of metal as well as dielectric films for bulge test. The process successfully combines the dry etching of deep reactive ion etching (DRIE) and XeF2 to release the test metal films. The Si3N4 film is used to protect the metal layers during the release process. Thus, the ion bombardment of the test metal films by DRIE is prevented. In addition, this process is also designed to prevent the pre-deformation of the Si3N4 and the metal films before release. By changing the recipe of XeF2 etching, the circular Si3N4 test membrane can also be fabricated. In applications, the circular membranes of Al, Au, and Si3N4 films were successfully prepared using the presented approach. This study also performed the bulge test by using these specimens to determine the thin film elastic modulus.

  17. Toxicological investigations in the semiconductor industry: IV. Studies on the subchronic oral toxicity and genotoxicity of vacuum pump oils contaminated by waste products from aluminum plasma etching processes.

    PubMed

    Bauer, S; Wolff, I; Werner, N; Schmidt, R; Blume, R; Pelzing, M

    1995-01-01

    Dry etching processes in semiconductor manufacturing use ionized gases in closed reactors at pressures below 1 torr. Vacuum pump systems that service the reaction chambers are potential sources of exposure to complex mixtures of inorganic and organic compounds. These mixtures consist of unused process gases and process by-products that condense and accumulate in the vacuum pump oils. To evaluate potential hazards of dry etch vacuum equipment, a contaminated vacuum pump oil sample from a BCl3/Cl2 etching process was analyzed. The waste oil was administered by gavage for 14 or 28 days to male and female Wistar rats. Neither death nor behavioral changes occurred after subchronic treatment or during a 14-day posttreatment period. Only slight effects on body weights, clinical chemistry, and hematology data were seen in the exposed animals, although the livers of all waste oil-exposed rats of both sexes showed remarkable hypertrophic degenerations. Genotoxicological investigations were performed through the Ames assay (Salmonella assay) and the Micronucleus assay. The contaminated oil sample caused clear genotoxic effects in both test systems. PMID:8677517

  18. Monitoring of inner wall condition in mass-production plasma etching process using a load impedance monitoring system

    NASA Astrophysics Data System (ADS)

    Kasashima, Yuji; Kurita, Hiroyuki; Kimura, Naoya; Ando, Akira; Uesugi, Fumihiko

    2015-06-01

    This work describes the detection of changes in the inner wall condition of mass-production plasma etching equipment using a load impedance monitoring system. The system detects the change in the imaginary part of the load impedance from a 50-Ω transmission line when the inner wall condition changes following exposure to the atmosphere. The results demonstrate that the system can be used as a practical method for real-time and noninvasive monitoring of the wall condition of etching chambers. This method will contribute to improvements in production yield and overall equipment effectiveness, and the development of predictive maintenance in semiconductor manufacturing.

  19. Metal etching composition

    NASA Technical Reports Server (NTRS)

    Otousa, Joseph E. (Inventor); Thomas, Clark S. (Inventor); Foster, Robert E. (Inventor)

    1991-01-01

    The present invention is directed to a chemical etching composition for etching metals or metallic alloys. The composition includes a solution of hydrochloric acid, phosphoric acid, ethylene glycol, and an oxidizing agent. The etching composition is particularly useful for etching metal surfaces in preparation for subsequent fluorescent penetrant inspection.

  20. Investigations of Wafer Scale Etching with Xenon Difluoride

    NASA Astrophysics Data System (ADS)

    Chen, K. N.; Hoivik, N.; Lin, C. Y.; Young, A.; Ieong, M.; Shahidi, G.

    2006-03-01

    A good and uniform bulk silicon wafer etching method can be applied to the wafer thinning process in MEMS and 3D applications. In this study, the use of a Xenon Difluoride (XeF2) gas-phase etching system, operating at room temperature, has been investigated for bulk silicon wafer thinning. We investigated the Si-wafer surface morphology and profile following each XeF2 etching process cycle. Theoretical results are used to compare with the experimental results as well. A clean wafer surface by proper surface treatments is significant to achieve a uniform surface profile and morphology for XeF2 etching. A proper design of etching cycle with nitrogen ambient during etching is necessary to achieve the fastest and uniform silicon etching rate. The silicon etching rate is reported as a function of etching pressure, nitrogen pressure, and etching duration.

  1. Reactive ion etching-induced damage in AlAs/InGaAs heterostructure field-effect transistors processed in HBR plasma

    SciTech Connect

    Fay, P.; Agarwala, S.; Scafidi, C.; Adesida, I.

    1994-11-01

    An investigation of the effects of HBr reactive ion etching (RIE) processing for gate recessing in lattice-matched InAlAl/InGaAs heterostructure field-effect transitors (HFETs) has been conducted. The effect of varying the Schottky barrier layer thickness on device performance and the susceptibility of HFETs to RIE-induced damage are presented for barrier layer thicknesses ranging from 10 to 25 nm. The effect of plasma self-bias voltage during gate recess etching on overall device performance for a given layer is assessed through direct current (dc) characterization and transconductance, threshold voltage, reverse gate leakage current, and gate-drain breakdown voltage, and through microwave characterization of the devices. Devices with barrier layers less than 20 nm thick are found to suffer the most degradation due to the RIE-induced damage. For devices with sufficiently thick barrier layers, dc and microwave device parameters compare well with those of corresponding devices fabricated using a selective wet-etch process. 10 refs., 5 figs., 1 tab.

  2. Spherical and Periodic Boundary Conditions in Ionic Charging Free Energies in a Polarizable Solvent

    NASA Astrophysics Data System (ADS)

    Herce, David Henry; Sagui, Celeste; Darden, Thomas

    2003-03-01

    In this work we present a method to compute ionic charging free energies in a polarizable water model in systems with periodic and spherical boundary conditions. The spherical clusters are treated via a generalization of Gauss law, which allows us to relate the microscopic electrostatics given by the point charges and point induced dipoles to the macroscopic electrostatic observables. In analogy to a similar work for ionic charging free energies in a non-polarizable environment, [Darden et al., J.Chem. Phys. 109, 10921 (1998)] , we find that the `interior' potential of the spherical cluster is consistent with the `P-summation' approach for charges proposed by by Hummer et al. [J. Phys. Chem. B 101, 3017 (1997)]. The charging free energies in the interior of the cluster agree, within simulation error, with those obtained by Ewald summation with finite-size corrections. In the cluster calculations, the difference between the external and internal electrostatic potentials gives the surface potential of the cluster.

  3. In-Plasma Photo-Assisted Etching

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2015-09-01

    A methodology to precisely control the ion energy distribution (IED) on a substrate allowed the study of silicon etching as a function of ion energy at near-threshold energies. Surprisingly, a substantial etching rate was observed, independent of ion energy, when the ion energy was below the ion-assisted etching threshold (~ 16 eV for etching silicon with chlorine plasma). Careful experiments led to the conclusion that this ``sub-threshold'' etching was due to photons, predominately at wavelengths <1700 Å. Among the plasmas investigated, photo-assisted etching (PAE) was lowest in Br2/Ar gas mixtures and highest in HBr/Cl2/Ar. Above threshold etching rates scaled with the square root of ion energy. PAE rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. In-plasma PAE may be be a complicating factor for processes that require low ion energies, such as atomic layer etching. On the other hand PAE could produce sub-10 nm high aspect ratio (6:1) features by highly selective plasma etching to transfer nascent nanopatterns in silicon. Work supported by DOE Plasma Science Center and NSF.

  4. Radicals Are Required for Thiol Etching of Gold Particles.

    PubMed

    Dreier, Timothy A; Ackerson, Christopher J

    2015-08-01

    Etching of gold with an excess of thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is unclear. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initiator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process.

  5. Radicals are required for thiol etching of gold particles

    PubMed Central

    Dreier, Timothy A.

    2016-01-01

    Etching of gold with excess thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is opaque. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process. PMID:26089294

  6. A Multi-Scale Study on Silicon-Oxide Etching Processes in C4F8/Ar Plasmas

    NASA Astrophysics Data System (ADS)

    Sui, Jiaxing; Zhang, Saiqian; Liu, Zeng; Yan, Jun; Dai, Zhongling

    2016-06-01

    A multi-scale numerical method coupled with the reactor, sheath and trench model is constructed to simulate dry etching of SiO2 in inductively coupled C4F8 plasmas. Firstly, ion and neutral particle densities in the reactor are decided using the CFD-ACE+ commercial software. Then, the ion energy and angular distributions (IEDs and IADs) are obtained in the sheath model with the sheath boundary conditions provided with CFD-ACE+. Finally, the trench profile evolution is simulated in the trench model. What we principally focus on is the effects of the discharge parameters on the etching results. It is found that the discharge parameters, including discharge pressure, radio-frequency (rf) power, gas mixture ratios, bias voltage and frequency, have synergistic effects on IEDs and IADs on the etched material surface, thus further affecting the trench profiles evolution. supported by National Natural Science Foundation of China (No. 11375040) and the Important National Science & Technology Specific Project of China (No. 2011ZX02403-002)

  7. Dry etching technologies for reflective multilayer

    NASA Astrophysics Data System (ADS)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Kase, Yoshihisa; Yoshimori, Tomoaki; Muto, Makoto; Nonaka, Mikio; Iwami, Munenori

    2012-11-01

    We have developed a highly integrated methodology for patterning Extreme Ultraviolet (EUV) mask, which has been highlighted for the lithography technique at the 14nm half-pitch generation and beyond. The EUV mask is characterized as a reflective-type mask which is completely different compared with conventional transparent-type of photo mask. And it requires not only patterning of absorber layer without damaging the underlying multi reflective layers (40 Si/Mo layers) but also etching multi reflective layers. In this case, the dry etch process has generally faced technical challenges such as the difficulties in CD control, etch damage to quartz substrate and low selectivity to the mask resist. Shibaura Mechatronics ARESTM mask etch system and its optimized etch process has already achieved the maximal etch performance at patterning two-layered absorber. And in this study, our process technologies of multi reflective layers will be evaluated by means of optimal combination of process gases and our optimized plasma produced by certain source power and bias power. When our ARES™ is used for multilayer etching, the user can choose to etch the absorber layer at the same time or etch only the multilayer.

  8. Controlled ion implant damage profile for etching

    DOEpatents

    Arnold, Jr., George W.; Ashby, Carol I. H.; Brannon, Paul J.

    1990-01-01

    A process for etching a material such as LiNbO.sub.3 by implanting ions having a plurality of different kinetic energies in an area to be etched, and then contacting the ion implanted area with an etchant. The various energies of the ions are selected to produce implant damage substantially uniformly throughout the entire depth of the zone to be etched, thus tailoring the vertical profile of the damaged zone.

  9. Ultra-high aspect ratio Si nanowires fabricated with plasma etching: plasma processing, mechanical stability analysis against adhesion and capillary forces and oleophobicity.

    PubMed

    Zeniou, A; Ellinas, K; Olziersky, A; Gogolides, E

    2014-01-24

    Room-temperature deep Si etching using time-multiplexed deep reactive ion etching (DRIE) processes is investigated to fabricate ultra-high aspect ratio Si nanowires (SiNWs) perpendicular to the silicon substrate. Nanopatterning is achieved using either top-down techniques (e.g. electron beam lithography) or colloidal polystyrene (PS) sphere self-assembly. The latter is a faster and more economical method if imperfections in diameter and position can be tolerated. We demonstrate wire radii from below 100 nm to several micrometers, and aspect ratios (ARs) above 100:1 with etching rates above 1 μm min(-1) using classical mass flow controllers with pulsing rise times of seconds. The mechanical stability of these nanowires is studied theoretically and experimentally against adhesion and capillary forces. It is shown that above ARs of the order of 50:1 for spacing 1 μm, SiNWs tend to bend due to adhesion forces between them. Such large adhesion forces are due to the high surface energy of silicon. Wetting the SiNWs with water and drying also gives rise to capillary forces. We find that capillary forces may be less important for SiNW collapse/bending compared to adhesion forces of dry SiNWs, contrary to what is observed for polymeric nanowires/nanopillars which have a much lower surface energy compared to silicon. Finally we show that SiNW arrays have oleophobic and superoleophobic properties, i.e. they exhibit excellent anti-wetting properties for a wide range of liquids and oils due to the re-entrant profile produced by the DRIE process and the well-designed spacing. PMID:24346308

  10. Ultra-high aspect ratio Si nanowires fabricated with plasma etching: plasma processing, mechanical stability analysis against adhesion and capillary forces and oleophobicity

    NASA Astrophysics Data System (ADS)

    Zeniou, A.; Ellinas, K.; Olziersky, A.; Gogolides, E.

    2014-01-01

    Room-temperature deep Si etching using time-multiplexed deep reactive ion etching (DRIE) processes is investigated to fabricate ultra-high aspect ratio Si nanowires (SiNWs) perpendicular to the silicon substrate. Nanopatterning is achieved using either top-down techniques (e.g. electron beam lithography) or colloidal polystyrene (PS) sphere self-assembly. The latter is a faster and more economical method if imperfections in diameter and position can be tolerated. We demonstrate wire radii from below 100 nm to several micrometers, and aspect ratios (ARs) above 100:1 with etching rates above 1 μm min-1 using classical mass flow controllers with pulsing rise times of seconds. The mechanical stability of these nanowires is studied theoretically and experimentally against adhesion and capillary forces. It is shown that above ARs of the order of 50:1 for spacing 1 μm, SiNWs tend to bend due to adhesion forces between them. Such large adhesion forces are due to the high surface energy of silicon. Wetting the SiNWs with water and drying also gives rise to capillary forces. We find that capillary forces may be less important for SiNW collapse/bending compared to adhesion forces of dry SiNWs, contrary to what is observed for polymeric nanowires/nanopillars which have a much lower surface energy compared to silicon. Finally we show that SiNW arrays have oleophobic and superoleophobic properties, i.e. they exhibit excellent anti-wetting properties for a wide range of liquids and oils due to the re-entrant profile produced by the DRIE process and the well-designed spacing.

  11. Ultra-high aspect ratio Si nanowires fabricated with plasma etching: plasma processing, mechanical stability analysis against adhesion and capillary forces and oleophobicity.

    PubMed

    Zeniou, A; Ellinas, K; Olziersky, A; Gogolides, E

    2014-01-24

    Room-temperature deep Si etching using time-multiplexed deep reactive ion etching (DRIE) processes is investigated to fabricate ultra-high aspect ratio Si nanowires (SiNWs) perpendicular to the silicon substrate. Nanopatterning is achieved using either top-down techniques (e.g. electron beam lithography) or colloidal polystyrene (PS) sphere self-assembly. The latter is a faster and more economical method if imperfections in diameter and position can be tolerated. We demonstrate wire radii from below 100 nm to several micrometers, and aspect ratios (ARs) above 100:1 with etching rates above 1 μm min(-1) using classical mass flow controllers with pulsing rise times of seconds. The mechanical stability of these nanowires is studied theoretically and experimentally against adhesion and capillary forces. It is shown that above ARs of the order of 50:1 for spacing 1 μm, SiNWs tend to bend due to adhesion forces between them. Such large adhesion forces are due to the high surface energy of silicon. Wetting the SiNWs with water and drying also gives rise to capillary forces. We find that capillary forces may be less important for SiNW collapse/bending compared to adhesion forces of dry SiNWs, contrary to what is observed for polymeric nanowires/nanopillars which have a much lower surface energy compared to silicon. Finally we show that SiNW arrays have oleophobic and superoleophobic properties, i.e. they exhibit excellent anti-wetting properties for a wide range of liquids and oils due to the re-entrant profile produced by the DRIE process and the well-designed spacing.

  12. Copper-assisted, anti-reflection etching of silicon surfaces

    SciTech Connect

    Toor, Fatima; Branz, Howard

    2014-08-26

    A method (300) for etching a silicon surface (116) to reduce reflectivity. The method (300) includes electroless deposition of copper nanoparticles about 20 nanometers in size on the silicon surface (116), with a particle-to-particle spacing of 3 to 8 nanometers. The method (300) includes positioning (310) the substrate (112) with a silicon surface (116) into a vessel (122). The vessel (122) is filled (340) with a volume of an etching solution (124) so as to cover the silicon surface (116). The etching solution (124) includes an oxidant-etchant solution (146), e.g., an aqueous solution of hydrofluoric acid and hydrogen peroxide. The silicon surface (116) is etched (350) by agitating the etching solution (124) with, for example, ultrasonic agitation, and the etching may include heating (360) the etching solution (124) and directing light (365) onto the silicon surface (116). During the etching, copper nanoparticles enhance or drive the etching process.

  13. An Experimental Study on Fabricating an Inverted Mesa-Type Quartz Crystal Resonator Using a Cheap Wet Etching Process

    PubMed Central

    Liang, Jinxing; Huang, Jia; Zhang, Tian; Zhang, Jing; Li, Xuefeng; Ueda, Toshitsugu

    2013-01-01

    In this study, a miniaturized high fundamental frequency quartz crystal microbalance (QCM) is fabricated for sensor applications using a wet etching technique. The vibration area is reduced in the fabrication of the high frequency QCM with an inverted mesa structure. To reduce the complexity of the side wall profile that results from anisotropic quartz etching, a rectangular vibration area is used instead of the conventional circular structure. QCMs with high Q values exceeding 25,000 at 47 MHz, 27,000 at 60 MHz, 24,000 at 73 MHz and 25,000 at 84 MHz are fabricated on 4 × 4 mm2 chips with small vibration areas of 1.2 × 1.4 mm2. A PMMA-based flow cell is designed and manufactured to characterize the behavior of the fabricated QCM chip in a liquid. Q values as high as 1,006 at 47 MHz, 904 at 62 MHz, 867 at 71 MHz and 747 at 84 MHz are obtained when one side of the chip is exposed to pure water. These results show that fabricated QCM chips can be used for bio- and chemical sensor applications in liquids. PMID:24025559

  14. Facile large-scale synthesis of brain-like mesoporous silica nanocomposites via a selective etching process.

    PubMed

    Chen, Yu; Wang, Qihua; Wang, Tingmei

    2015-10-21

    The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume of 1.0 cm(3) g(-1). The novelty of this approach lies in the use of an inorganic-organic hybrid layer to assist the creation of large-pore morphology on the outermost shell thereby promoting efficient mass transfer or storage. Importantly, the method is reliable and grams of products can be easily prepared. The morphology on the outermost silica shell can be controlled by simply adjusting the VTES-to-TEOS molar ratio (VTES: triethoxyvinylsilane, TEOS: tetraethyl orthosilicate) as well as the etching time. The as-synthesized products exhibit fluorescence performance by incorporating rhodamine B isothiocyanate (RITC) covalently into the inner silica walls, which provide potential application in bioimaging. We also demonstrate the applications of as-synthesized large-pore structured nanocomposites in drug delivery systems and stimuli-responsive nanoreactors for heterogeneous catalysis. PMID:26394819

  15. An experimental study on fabricating an inverted mesa-type quartz crystal resonator using a cheap wet etching process.

    PubMed

    Liang, Jinxing; Huang, Jia; Zhang, Tian; Zhang, Jing; Li, Xuefeng; Ueda, Toshitsugu

    2013-09-10

    In this study, a miniaturized high fundamental frequency quartz crystal microbalance (QCM) is fabricated for sensor applications using a wet etching technique. The vibration area is reduced in the fabrication of the high frequency QCM with an inverted mesa structure. To reduce the complexity of the side wall profile that results from anisotropic quartz etching, a rectangular vibration area is used instead of the conventional circular structure. QCMs with high Q values exceeding 25,000 at 47 MHz, 27,000 at 60 MHz, 24,000 at 73 MHz and 25,000 at 84 MHz are fabricated on 4 × 4 mm2 chips with small vibration areas of 1.2 × 1.4 mm2. A PMMA-based flow cell is designed and manufactured to characterize the behavior of the fabricated QCM chip in a liquid. Q values as high as 1,006 at 47 MHz, 904 at 62 MHz, 867 at 71 MHz and 747 at 84 MHz are obtained when one side of the chip is exposed to pure water. These results show that fabricated QCM chips can be used for bio- and chemical sensor applications in liquids.

  16. An experimental study on fabricating an inverted mesa-type quartz crystal resonator using a cheap wet etching process.

    PubMed

    Liang, Jinxing; Huang, Jia; Zhang, Tian; Zhang, Jing; Li, Xuefeng; Ueda, Toshitsugu

    2013-01-01

    In this study, a miniaturized high fundamental frequency quartz crystal microbalance (QCM) is fabricated for sensor applications using a wet etching technique. The vibration area is reduced in the fabrication of the high frequency QCM with an inverted mesa structure. To reduce the complexity of the side wall profile that results from anisotropic quartz etching, a rectangular vibration area is used instead of the conventional circular structure. QCMs with high Q values exceeding 25,000 at 47 MHz, 27,000 at 60 MHz, 24,000 at 73 MHz and 25,000 at 84 MHz are fabricated on 4 × 4 mm2 chips with small vibration areas of 1.2 × 1.4 mm2. A PMMA-based flow cell is designed and manufactured to characterize the behavior of the fabricated QCM chip in a liquid. Q values as high as 1,006 at 47 MHz, 904 at 62 MHz, 867 at 71 MHz and 747 at 84 MHz are obtained when one side of the chip is exposed to pure water. These results show that fabricated QCM chips can be used for bio- and chemical sensor applications in liquids. PMID:24025559

  17. Analytical model of plasma-chemical etching in planar reactor

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Bakun, A. D.; Voronov, Yu A.; Kireev, V. Yu; Vasileva, O. V.

    2016-09-01

    The paper discusses an analytical model of plasma-chemical etching in planar diode- type reactor. Analytical expressions of etch rate and etch anisotropy were obtained. It is shown that etch anisotropy increases with increasing the ion current and ion energy. At the same time, etch selectivity of processed material decreases as compared with the mask. Etch rate decreases with the distance from the centre axis of the reactor. To decrease the loading effect, it is necessary to reduce the wafer temperature and pressure in the reactor, as well as increase the gas flow rate through the reactor.

  18. TOPICAL REVIEW: Black silicon method X: a review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

    NASA Astrophysics Data System (ADS)

    Jansen, H V; de Boer, M J; Unnikrishnan, S; Louwerse, M C; Elwenspoek, M C

    2009-03-01

    An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O2) or a fluorocarbon (FC) gas (C4F8 or CHF3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication of directional profiles, pulsed-mode DRIE is far easier to handle, is more robust with respect to the pattern layout and has the potential of achieving much higher mask etch selectivity, whereas in a mixed-mode the etch rate is higher and sidewall scalloping is prohibited. It is found that both pulsed-mode CHF3 and C4F8 are perfectly suited to perform high speed directional etching, although they have the drawback of leaving the FC residue at the sidewalls of etched structures. They show an identical result when the flow of CHF3 is roughly 30 times the flow of C4F8, and the amount of gas needed for a comparable result decreases rapidly while lowering the temperature from room down to cryogenic (and increasing the etch rate). Moreover, lowering the temperature lowers the mask erosion rate substantially (and so the mask selectivity improves). The pulsed-mode O2 is FC-free but shows only tolerable anisotropic results at -120 °C. The

  19. Facile large-scale synthesis of brain-like mesoporous silica nanocomposites via a selective etching process

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Wang, Qihua; Wang, Tingmei

    2015-10-01

    The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume of 1.0 cm3 g-1. The novelty of this approach lies in the use of an inorganic-organic hybrid layer to assist the creation of large-pore morphology on the outermost shell thereby promoting efficient mass transfer or storage. Importantly, the method is reliable and grams of products can be easily prepared. The morphology on the outermost silica shell can be controlled by simply adjusting the VTES-to-TEOS molar ratio (VTES: triethoxyvinylsilane, TEOS: tetraethyl orthosilicate) as well as the etching time. The as-synthesized products exhibit fluorescence performance by incorporating rhodamine B isothiocyanate (RITC) covalently into the inner silica walls, which provide potential application in bioimaging. We also demonstrate the applications of as-synthesized large-pore structured nanocomposites in drug delivery systems and stimuli-responsive nanoreactors for heterogeneous catalysis.The core-shell structured mesoporous silica nanomaterials (MSNs) are experiencing rapid development in many applications such as heterogeneous catalysis, bio-imaging and drug delivery wherein a large pore volume is desirable. We develop a one-pot method for large-scale synthesis of brain-like mesoporous silica nanocomposites based on the reasonable change of the intrinsic nature of the -Si-O-Si- framework of silica nanoparticles together with a selective etching strategy. The as-synthesized products show good monodispersion and a large pore volume

  20. Multilayer Badges Indicate Depths Of Ion Sputter Etches

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Matossian, J. N.; Garvin, H. L.

    1994-01-01

    Multilayer badges devised to provide rapid, in-place indications of ion sputter etch rates. Badges conceived for use in estimating ion erosion of molybdenum electrodes used in inert-gas ion thrustors. Concept adapted to measure ion erosion in industrial sputter etching processes used for manufacturing of magnetic, electronic, and optical devices. Badge etched when bombarded by energetic ions. Badge layers exposed using mask. Contrast between layers facilitates counting of layers to determine etch depth.

  1. 2D-t modeling of pulsed-2f-CCP in CF_4(5%)/Ar for oxide etching

    NASA Astrophysics Data System (ADS)

    Washio, G.; Maeshige, K.; Nakano, N.; Makabe, T.

    2000-10-01

    Capacitively coupled plasma (CCP) source with different frequency source at each of parallel plate electrodes is a powerful tool for doing etching. A time modulation of CCP by a pulsed-power operation may be one of the practical solution of the development of the charging free plasma process for etching. Then, (very) high frequency (VHF) power source is operated in a pulse mode, although the opposite bias electrode with patterned wafer is in cw operation at low frequency (LF). In this study, modeling has been performed in order to investigate the fluxed of positive and negative ions, and electrons to the wafer surface as a function of frequency (13.56 MHz, 100 MHz), amplitude and on/off period of the (V)HF source, as well as the amplitude of the LF (678 kHz) bias voltage at 50 mTorr in CF_4(5%)/Ar. We employed the RCT model, and also a hybrid model(E.Shidoji, N.Nakano, T.Makabe, Thin Solid Films 351 (1999) 37-41) consisting of Monte Carlo particle model of fast electrons and the RCT model. In particular, we discuss the rule of negative ions on the wafer surface during off-period in CF_4/Ar system with dissociative electron attachment at finite electron energy without thermal attachment.

  2. Investigation and simulation of XeF2 isotropic etching of silicon

    NASA Astrophysics Data System (ADS)

    Bahreyni, Behraad; Shafai, C.

    2002-11-01

    Trenching and loading phenomena observed on XeF2-etched (100) silicon wafers are explained in this article. Trenching refers to deeper etching at the side of an etch feature with respect to the middle of the feature. Loading is the reduction in etch depth that adjacent etched regions impose on their respective etch profiles. These two phenomena are especially recognized at locations where the substrate is etched through large mask openings. Both phenomena were reported by other groups, but no explanation was given for them. A novel model explaining these phenomena is developed in this article, and the etching process is simulated in software. The results are compared to several etched samples with varying mask aperture size and etch depth. Good agreement is found between simulated profiles and actual measured etch profiles at given mean-free paths. Furthermore, our simulator predicts that the reaction probability between etchant and substrate molecules influences surface roughness of the etched regions.

  3. Simulation of Etching Profiles Using Level Sets

    NASA Technical Reports Server (NTRS)

    Hwang, Helen; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Using plasma discharges to etch trenches and via holes in substrates is an important process in semiconductor manufacturing. Ion enhanced etching involves both neutral fluxes, which are isotropic, and ion fluxes, which are anisotropic. The angular distributions for the ions determines the degree of vertical etch, while the amount of the neutral fluxes determines the etch rate. We have developed a 2D profile evolution simulation which uses level set methods to model the plasma-substrate interface. Using level sets instead of traditional string models avoids the use of complicated delooping algorithms. The simulation calculates the etch rate based on the fluxes and distribution functions of both ions and neutrals. We will present etching profiles of Si substrates in low pressure (10s mTorr) Ar/Cl2 discharges for a variety of incident ion angular distributions. Both ion and neutral re-emission fluxes are included in the calculation of the etch rate, and their contributions to the total etch profile will be demonstrated. In addition, we will show RIE lag effects as a function of different trench aspect ratios. (For sample profiles, please see http://www.ipt.arc.nasa.gov/hwangfig1.html)

  4. Plasma etching of the Group-III nitrides

    SciTech Connect

    Shul, R.; Pearton, S.J.; Abernathy, C.R.

    1996-01-01

    In reactive ion etching (RIE) of GaN, the ion bombardment can damage the material, so it is necessary to develop plasma etch processes. This paper reports etching of GaN in an ECR (electron cyclotron resonance) etch system using both the ECR/RIE mode and the RIE-only mode. Group III (Ga, In, Al) nitride ECR etching is reviewed as a function of plasma chemistry, power, temperature, and pressure; as the ECR microwave power increased, the ion density and etch rates increased, with the etch rate increasing the most for InN. GaN etch rates > 6500 {angstrom}/min have been observed in the ECR/RIE mode. 2 figs, 6 refs.

  5. Characterization of silicon isotropic etch by inductively coupled plasma etcher for microneedle array fabrication

    NASA Astrophysics Data System (ADS)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin; Sun, Jianbo

    2006-04-01

    This work investigates the isotropic etching properties in inductively coupled plasma (ICP) etcher for microneedle arrays fabrication. The effects of process variables including powers, gas and pressure on needle structure generation are characterized by factorial design of experiment (DOE). The experimental responses of vertical etching depth, lateral etching length, ratio of vertical etching depth to lateral etching length and photoresist etching rate are reported. The relevance of the etching variables is also presented. The obtained etching behaviours for microneedle structure generation will be applied to develop recipes to fabricate microneedles in designed dimensions.

  6. Research on wet etching at MEMS torsion mirror optical switch

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Wang, Jifeng; Luo, Yuan

    2002-10-01

    Etching is a very important technique at MEMS micromachining. There are two kinds of etching processing, the one is wet etching and the other is dry etching. In this paper, wet selective etching with KOH and tetramethyl ammonium hydroxide (TMAH) etchants is researched in order to make a torsion mirror optical switch. The experiments results show that TMAH with superphosphate is more suitable at MEMS torsion mirror optical switch micromachining than KOH, and it also has good compatibility with IC processing. Also our experiments results show some different with other reported research data. More work will be done to improve the yield rate of MEMS optical switch.

  7. Chemical etching of nitinol stents.

    PubMed

    Katona, Bálint; Bognár, Eszter; Berta, Balázs; Nagy, Péter; Hirschberg, Kristóf

    2013-01-01

    At present the main cause of death originates from cardiovascular diseases. Primarily the most frequent cause is vessel closing thus resulting in tissue damage. The stent can help to avoid this. It expands the narrowed vessel section and allows free blood flow. The good surface quality of stents is important. It also must have adequate mechanical characteristics or else it can be damaged which can easily lead to the fracture of the implant. Thus, we have to consider the importance of the surface treatment of these implants. In our experiments the appropriate design was cut from a 1.041 mm inner diameter and 0.100 mm wall thickness nitinol tube by using Nd:YAG laser device. Then, the stent was subjected to chemical etching. By doing so, the burr created during the laser cutting process can be removed and the surface quality refined. In our research, we changed the time of chemical etching and monitored the effects of this parameter. The differently etched stents were subjected to microscopic analysis, mass measurement and in vivo environment tests. The etching times that gave suitable surface and mechanical features were identified.

  8. Silver coated platinum core-shell nanostructures on etched Si nanowires: atomic layer deposition (ALD) processing and application in SERS.

    PubMed

    Sivakov, Vladimir A; Höflich, Katja; Becker, Michael; Berger, Andreas; Stelzner, Thomas; Elers, Kai-Erik; Pore, Viljami; Ritala, Mikko; Christiansen, Silke H

    2010-06-21

    A new method to prepare plasmonically active noble metal nanostructures on large surface area silicon nanowires (SiNWs) mediated by atomic layer deposition (ALD) technology has successfully been demonstrated for applications of surface-enhanced Raman spectroscopy (SERS)-based sensing. As host material for the plasmonically active nanostructures we use dense single-crystalline SiNWs with diameters of less than 100 nm as obtained by a wet chemical etching method based on silver nitrate and hydrofluoric acid solutions. The SERS active metal nanoparticles/islands are made from silver (Ag) shells as deposited by autometallography on the core nanoislands made from platinum (Pt) that can easily be deposited by ALD in the form of nanoislands covering the SiNW surfaces in a controlled way. The density of the plasmonically inactive Pt islands as well as the thickness of noble metal Ag shell are two key factors determining the magnitude of the SERS signal enhancement and sensitivity of detection. The optimized Ag coated Pt islands on SiNWs exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability and reproducibility. The plasmonic activity of the core-shell Pt//Ag system that will be experimentally realized in this paper as an example was demonstrated in numerical finite element simulations as well as experimentally in Raman measurements of SERS activity of a highly diluted model dye molecule. The morphology and structure of the core-shell Pt//Ag nanoparticles on SiNW surfaces were investigated by scanning- and transmission electron microscopy. Optimized core-shell nanoparticle geometries for maximum Raman signal enhancement is discussed essentially based on the finite element modeling.

  9. Fe-catalyzed etching of graphene layers

    NASA Astrophysics Data System (ADS)

    Cheng, Guangjun; Calizo, Irene; Hight Walker, Angela; PML, NIST Team

    We investigate the Fe-catalyzed etching of graphene layers in forming gas. Fe thin films are deposited by sputtering onto mechanically exfoliated graphene, few-layer graphene (FLG), and graphite flakes on a Si/SiO2 substrate. When the sample is rapidly annealed in forming gas, particles are produced due to the dewetting of the Fe thin film and those particles catalyze the etching of graphene layers. Monolayer graphene and FLG regions are severely damaged and that the particles catalytically etch channels in graphite. No etching is observed on graphite for the Fe thin film annealed in nitrogen. The critical role of hydrogen indicates that this graphite etching process is catalyzed by Fe particles through the carbon hydrogenation reaction. By comparing with the etched monolayer and FLG observed for the Fe film annealed in nitrogen, our Raman spectroscopy measurements identify that, in forming gas, the catalytic etching of monolayer and FLG is through carbon hydrogenation. During this process, Fe particles are catalytically active in the dissociation of hydrogen into hydrogen atoms and in the production of hydrogenated amorphous carbon through hydrogen spillover.

  10. Enhanced ferro-actuator with a porosity-controlled membrane using the sol-gel process and the HF etching method

    NASA Astrophysics Data System (ADS)

    Kim, KiSu; Ko, Seong Young; Park, Jong-Oh; Park, Sukho

    2016-01-01

    In this paper, we propose a ferro-actuator using a porous polyvinylidene difluoride (PVDF) membrane. In detail, we fabricated the silica-embedded PVDF membrane using a sol-gel process with PVDF solution and tetraethyl orthosilicate (TEOS) solution, where the size of the silica was determined by the ratio of the PVDF and TEOS solutions. Using hydrofluoric acid (HF) etching, the silica were removed from the silica-embedded PVDF membrane, and porous PVDF membranes with different porosities were obtained. Finally, through absorption of a ferrofluid on the porous PVDF membrane, the proposed ferro-actuator using porous PVDF membranes with different porosities was fabricated. We executed the characterization and actuation test as follows. First, the silica size of the silica-embedded PVDF membrane and the pore size of the porous PVDF membrane were analyzed using scanning electron microscopy (SEM) imaging. Second, energy-dispersive x-ray spectroscopy analysis showed that the silica had clearly been removed from the silica-embedded PVDF membrane by HF etching. Third, through x-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) of the ferro-actuators, we found that more ferrofluids were absorbed by the porous PVDF membrane when the pore of the membrane was smaller and uniformly distributed. Finally, we executed tip displacement and a blocking force test of the proposed ferro-actuator using the porous PVDF membrane. Similar to the VSM result, the ferro-actuator that used a porous PVDF membrane with smaller pores exhibited better actuation performance. The ferro-actuator that used a porous PVDF membrane displayed a tip displacement that was about 7.2-fold better and a blocking force that was about 6.5-fold better than the ferro-actuator that used a pure PVDF membrane. Thus, we controlled the pore size of the porous PVDF membrane and enhanced the actuation performance of the ferro-actuator using a porous PVDF membrane.

  11. Reactive sputter etching of magnetic materials in an HCl plasma

    SciTech Connect

    Heijman, M.G.J.

    1988-12-01

    In an rf low-pressure HCl plasma NiZn and MnZn ferrite etch up to five times as fast as in an otherwise comparable Ar sputter etch process. Selectivity towards Al/sub 2/O/sub 3/ as an etch mask is of order 10. No redeposited material and very little trenching are seen. The etched slopes have a steepness up to 70/sup 0/, resulting from redeposition and enhanced etching on the sidewalls. This is shown by experiments and by computer simulations.

  12. ICP etching of GaAs via hole contacts

    SciTech Connect

    Shul, R.J.; Baca, A.G.; Briggs, R.D.; McClellan, G.B.; Pearton, S.J.; Constantine, C.

    1996-09-01

    Deep etching of GaAs is a critical process step required for many device applications including fabrication of through-substrate via holes for monolithic microwave integrated circuits (MMICs). Use of high-density plasmas, including inductively coupled plasmas (ICP), offers an alternative approach to etching vias as compared to more conventional parallel plate reactive ion etch systems. This paper reports ICP etching of GaAs vias at etch rates of about 5.3 {mu}m/min with via profiles ranging from highly anistropic to conical.

  13. Chemically assisted ion beam etching of polycrystalline and (100)tungsten

    NASA Technical Reports Server (NTRS)

    Garner, Charles

    1987-01-01

    A chemically assisted ion-beam etching technique is described which employs an ion beam from an electron-bombardment ion source and a directed flux of ClF3 neutrals. This technique enables the etching of tungsten foils and films in excess of 40 microns thick with good anisotropy and pattern definition over areas of 30 sq mm, and with a high degree of selectivity. (100) tungsten foils etched with this process exhibit preferred-orientation etching, while polycrystalline tungsten films exhibit high etch rates. This technique can be used to pattern the dispenser cathode surfaces serving as electron emitters in traveling-wave tubes to a controlled porosity.

  14. Si etching with reactive neutral beams of very low energy

    SciTech Connect

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Iwata, Naotaka; Hara, Tamio

    2014-12-14

    A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

  15. Modeling Wet Chemical Etching of Surface Flaws on Fused Silica

    SciTech Connect

    Feit, M D; Suratwala, T I; Wong, L L; Steele, W A; Miller, P E; Bude, J D

    2009-10-28

    Fluoride-based wet chemical etching of fused silica optical components is useful to open up surface fractures for diagnostic purposes, to create surface topology, and as a possible mitigation technique to remove damaged material. To optimize the usefulness of etching , it is important to understand how the morphology of etched features changes as a function of the amount of material removed. In this study, we present two geometric etch models that describe the surface topology evolution as a function of the amount etched. The first model, referred to as the finite-difference etch model, represents the surface as an array of points in space where at each time-step the points move normal to the local surface. The second model, referred to as the surface area-volume model, more globally describes the surface evolution relating the volume of material removed to the exposed surface area. These etch models predict growth and coalescence of surface fractures such as those observed on scratches and ground surfaces. For typical surface fractures, simulations show that the transverse growth of the cracks at long etch times scales with the square root of etch time or the net material removed in agreement with experiment. The finite-difference etch model has also been applied to more complex structures such as the etching of a CO{sub 2} laser-mitigated laser damage site. The results indicate that etching has little effect on the initial morphology of this site implying little change in downstream scatter and modulation characteristics upon exposure to subsequent high fluence laser light. In the second part of the study, the geometric etch model is expanded to include fluid dynamics and mass transport. This later model serves as a foundation for understanding related processes such as the possibility of redeposition of etch reaction products during the etching, rinsing or drying processes.

  16. Etching rate control of mask material for XeF2 etching using UV exposure

    NASA Astrophysics Data System (ADS)

    Sugano, Koji; Tabata, Osamu

    2001-09-01

    A new technique to control etching rates of mask materials during XeF2 etching was proposed. By exposing Si sample with SiO2 and Si3N4 as mask materials to UV light of 3 W/cm2 during XeF2 etching, the etching rates of SiO2 and Si3N4 were dramatically increased from 2.52 angstrom/pulse to 42.0 angstrom/pulse and from 27.3 angstrom/pulse to 403 angstrom/pulse, respectively. This new technique allows us to remove the mask material selectively and change the mask pattern by UV light exposure during in- situ etching process without additional photolithography step and opens a new silicon micromachining process for 3- dimensional fabrication. The multi-step Si structure was successfully realized by this technique.

  17. Dynamics of ion-assisted etching

    NASA Astrophysics Data System (ADS)

    Sebel, Petrus Gerardus Maria

    In this thesis a study is presented on the fundamentals of ion-assisted etching of silicon. The research was performed in the Atomic Physics and Quantum Electronics Group (AQT/B) of the Physics Department at the Eindhoven University of Technology. Etching is a key technique in the production process of integrated circuits. Industrial etching is usually done in a plasma reactor. However, to unravel the detailed mechanisms determining the etch process, a different approach was chosen. In this scheme, well defined beams of XeF2 and Ar + ions are directed towards the Si sample in an ultra-high vacuum (UHV) setup. In this way the relevant ingredients of a plasma (neutrals and ions) are simulated. The etching reaction is monitored by a quadruple mass spectrometer (QMS) which detects the desorption of non-reacted XeF2 and the main reaction products SiF4 and SiF2. We conclude that we have obtained a detailed microscopic picture of the etching of silicon by beams of neutrals and ions. However, there is still a gap between beam etching and plasma etching. To bridge this gap an ellipsometer has been added to our setup, because it is a common non-invasive diagnostic tool used in a plasma reactor. In addition, also a sample exchange mechanism was installed to facilitate the frequent exchange of samples. The first ellipsometric results of spontaneous etching show the construction of a reaction layer followed by surface roughening. The XeF2 dose needed to build the reaction layer as derived from the ellipsometric results is in good agreement with results from the mass spectrometer. Additional experiments have to be performed to obtain a full understanding of the roughening of the surface, but a first link between microscopic and macroscopic features has been established. (Abstract shortened by UMI.)

  18. Plasma damage mechanisms for low-k porous SiOCH films due to radiation, radicals, and ions in the plasma etching process

    SciTech Connect

    Uchida, Saburo; Takashima, Seigo; Hori, Masaru; Fukasawa, Masanaga; Ohshima, Keiji; Nagahata, Kazunori; Tatsumi, Tetsuya

    2008-04-01

    Low dielectric constant (low-k) films have been widely used as insulating materials in ultra-large-scale integrated circuits. Low-k films receive heavy damage during the plasma processes of etching or ashing, resulting in an increase in their dielectric constant. In order to realize damage-free plasma processes for low-k films, it is essential to determine the influence of radiation, radicals, and ions emitted in the plasma process on the characteristics of low-k films. We have developed a technique to evaluate the influence of radiation, radicals, ions, and their synergies on films in real plasma processes and have named it pallet for plasma evaluation (PAPE). Using the PAPE, plasma-induced damage on porous SiOCH films were investigated in dual-frequency capacitively coupled H{sub 2}/N{sub 2} plasmas. The damage was characterized by ellipsometry, Fourier-transform infrared spectroscopy, and thermal desorption spectroscopy. On the basis of the results, the damage mechanisms associated with vacuum ultraviolet (VUV) and UV radiation, radicals, and ions were clarified. The damage was caused not only by ions and radicals but also by VUV and UV radiation emitted by the plasmas. Moreover, it was found that the synergy between the radiation and the radicals enhanced the damage.

  19. Development of Localized Plasma Etching System for Failure Analyses in Semiconductor Devices: (3)
    Etching-Monitoring Using Quadrupole Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Takahashi, Satoshi; Horie, Tomoyuki; Shirayama, Yuya; Yokosuka, Shuntaro; Kashimura, Kenta; Hayashi, Akihiro; Iwase, Chikatsu; Shimbori, Shun'ichiro; Tokumoto, Hiroshi; Naitoh, Yasuhisa; Shimizu, Tetsuo

    Quadrupole mass spectrometry (QMS) has been applied to monitor the etching processes in a localized plasma etching system. An inward plasma was employed for etching in which the etching gas was discharged in the narrow gap between the etched sample and the entrance of an evacuating capillary tube. As the etching products are immediately evacuated through the capillary, a QMS system equipped at the capillary exit is able to analyze the products without any loss in concentration via diffusion into the chamber. Two kinds of samples, thermally grown SiO2 on Si and spin-coated polyimide film on Si, were etched, and the chemical species in the evacuated etching gas were analyzed with QMS, which enables monitoring of the composition of the surface being etched. Samples of thermal SiO2 were etched with CF4 plasma. The peak height of the SiF3+ signal during the SiO2 etching was lower than that observed during etching of the silicon substrate, leading to endpoint detection. The endpoint detection of the polyimide film etching was conducted using two etching gases: pure O2 and pure CF4. When O2 was used, the endpoint was detected by the decrease of the mass peak attributed to CO. When CF4 was employed, the plasma was able to etch both the polyimide film and Si substrate. Then the endpoint was detected by the increase of the mass peak of SiF3+ produced by the etching of the Si substrate.

  20. Steric stabilization of "charge-free" cellulose nanowhiskers by grafting of poly(ethylene glycol).

    PubMed

    Araki, Jun; Mishima, Shiho

    2015-01-01

    A sterically stabilized aqueous suspension of "charge-free" cellulose nanowhiskers was prepared by hydrochloric acid hydrolysis of cotton powders and subsequent surface grafting of monomethoxy poly(ethylene glycol) (mPEG). The preparation scheme included carboxylation of the terminal hydroxyl groups in mPEG via oxidation with silica gel particles carrying 2,2,6,6-tetramethyl-1-pyperidinyloxyl (TEMPO) moieties and subsequent esterification between terminal carboxyls in mPEG and surface hydroxyl groups of cellulose nanowhiskers, mediated by 1,1'-carbonyldiimidazole (CDI) in dimethyl sulfoxide or dimethylacetamide. Some of the prepared PEG-grafted samples showed remarkable flow birefringence and enhanced stability after 24 h, even in 0.1 M NaCl, suggesting successful steric stabilization by efficient mPEG grafting. Actual PEG grafting via ester linkages was confirmed by attenuated total reflectance-Fourier transform infrared spectrometry. In a typical example, the amount of grafted mPEG was estimated as ca. 0.3 g/g cellulose by two measurements, i.e., weight increase after grafting and weight loss after alkali cleavage of ester linkages. Transmission electron microscopy indicated unchanged nanowhisker morphology after mPEG grafting. PMID:25547722

  1. Plasma characteristics and etch uniformity in CF4 magnetron etching using an annular permanent magnet

    NASA Astrophysics Data System (ADS)

    Kinoshita, Haruhisa; Ishida, Toshimasa; Ohno, Seigo

    1987-11-01

    Etch characteristics of SiO2 and Si obtained by magnetron etching using an annular permanent magnet were analyzed. From these analyses, etch characteristics were found to be classified into three regimes. Remarkable enhancements in SiO2 etch rate, 25-40 times, were observed at constant Vrf by applying magnetic field of 150 G. Ion densities over the cathode were found to be distributed linearly along the E×B drift direction. Such an ion density distribution will be formed by the repeated process (ionization→ion bombardment→electron emission and drift→ionization). Etch distribution can be averaged and flattened to a uniformity of below ±2% by the magnetic field being rotated in 90° steps.

  2. Etching characteristics of LiNbO{sub 3} in reactive ion etching and inductively coupled plasma

    SciTech Connect

    Ren, Z.; Yu, S.; Heard, P. J.; Marshall, J. M.; Thomas, P. A.

    2008-02-01

    The etching characteristics of congruent LiNbO{sub 3} single crystals including doped LiNbO{sub 3} and proton-changed LiNbO{sub 3} have been studied in reactive ion etching (RIE) and inductively coupled plasma (ICP) etching tools, using different recipes of gas mixtures. The effects of parameters including working pressure, RIE power, and ICP power are investigated and analyzed by measurement of etching depth, selectivity, uniformity, etched surface state, and sidewall profile by means of focused ion beam etching, energy-dispersive x-ray analysis, secondary ion mass spectroscopy, scanning electron microscopy, and surface profilometry. The effects of a sample carrier wafer coating have also been investigated. Optimized processes with high etching rates, good mask selectivity, and a near-vertical profile have been achieved. Ridge waveguides on proton-exchanged LiNbO{sub 3} have been fabricated and optically measured.

  3. Black Germanium fabricated by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Steglich, Martin; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-09-01

    A reactive ion etching technique for the preparation of statistical "Black Germanium" antireflection surfaces, relying on self-organization in a Cl2 etch chemistry, is presented. The morphology of the fabricated Black Germanium surfaces is the result of a random lateral distribution of pyramidal etch pits with heights around (1450 ± 150) nm and sidewall angles between 80° and 85°. The pyramids' base edges are oriented along the <110> crystal directions of Germanium, indicating a crystal anisotropy of the etching process. In the Vis-NIR, the tapered Black Germanium surface structure suppresses interface reflection to <2.5 % for normal incidence and still to <6 % at an angle of incidence of 70°. The presented Black Germanium might find applications as low-cost AR structure in optoelectronics and IR optics.

  4. Epoxy bond and stop etch fabrication method

    DOEpatents

    Simmons, Jerry A.; Weckwerth, Mark V.; Baca, Wes E.

    2000-01-01

    A class of epoxy bond and stop etch (EBASE) microelectronic fabrication techniques is disclosed. The essence of such techniques is to grow circuit components on top of a stop etch layer grown on a first substrate. The first substrate and a host substrate are then bonded together so that the circuit components are attached to the host substrate by the bonding agent. The first substrate is then removed, e.g., by a chemical or physical etching process to which the stop etch layer is resistant. EBASE fabrication methods allow access to regions of a device structure which are usually blocked by the presence of a substrate, and are of particular utility in the fabrication of ultrafast electronic and optoelectronic devices and circuits.

  5. Application of an RF Biased Langmuir Probe to Etch Reactor Chamber Matching, Fault Detection and Process Control

    NASA Astrophysics Data System (ADS)

    Keil, Douglas; Booth, Jean-Paul; Benjamin, Neil; Thorgrimsson, Chris; Brooks, Mitchell; Nagai, Mikio; Albarede, Luc; Kim, Jung

    2008-10-01

    Semiconductor device manufacturing typically occurs in an environment of both increasing equipment costs and per unit sale price shrinkage. Profitability in such a conflicted economic environment depends critically on yield, throughput and cost-of-ownership. This has resulted in increasing interest in improved fault detection, process diagnosis, and advanced process control. Achieving advances in these areas requires an integrated understanding of the basic physical principles driving the processes of interest and the realities of commercial manufacturing. Following this trend, this work examines the usefulness of an RF-biased planar Langmuir probe^1. This method delivers precise real-time (10 Hz) measurements of ion flux and tail weighted electron temperature. However, it is also mechanically non-intrusive, reliable and insensitive to contamination and deposition on the probe. Since the measured parameters are closely related to physical processes occurring at the wafer-plasma interface, significant improvements in process control, chamber matching and fault detection are achieved. Examples illustrating the improvements possible will be given. ^1J.P. Booth, N. St. J. Braithwaite, A. Goodyear and P. Barroy, Rev.Sci.Inst., Vol.71, No.7, July 2000, pgs. 2722-2727.

  6. Metal assisted anodic etching of silicon.

    PubMed

    Lai, Chang Quan; Zheng, Wen; Choi, W K; Thompson, Carl V

    2015-07-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P(+)-type and N(+)-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P(+)-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N(+)-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si. PMID:26059556

  7. Solvothermal-Etching Process Induced Ti-Doped Fe2O3 Thin Film with Low Turn-On Voltage for Water Splitting.

    PubMed

    Ding, Dawei; Dong, Bitao; Liang, Jin; Zhou, Han; Pang, Yuanchao; Ding, Shujiang

    2016-09-21

    In this work, a thinning process of hematite film accompanied by simultaneous titanium (Ti) doping has been demonstrated. Ti(4+) ion was incorporated into ultrathin Fe2O3 film by solvothermally etching a hematite film fabricated on titanium nanorod array substrate. As a consequence, the onset potential (Von) of oxygen evolution reaction for final ultrathin Ti-doped Fe2O3 film shifted toward cathodic substantially, a very low Von of 0.48 VRHE was realized, approximately 0.53 V cathodic shift of the hematite film. Working mechanisms were investigated from both kinetic and thermodynamic ways. The ultrathin Ti-doped Fe2O3 film exhibited reduced Tafel slope and higher generated photovoltage than the pristine Fe2O3 electrode. Moreover, the highly doped Fe2O3 resulted in significant reduction of charge-transfer resistance at the Fe2O3∥electrolyte interface. The drastic cathodic-shift Von is believed to be a result of combined factors including thermodynamic contribution, improved surface reaction kinetics, as well as facilitated charge transfer across bulk and interface. PMID:27557165

  8. Solvothermal-Etching Process Induced Ti-Doped Fe2O3 Thin Film with Low Turn-On Voltage for Water Splitting.

    PubMed

    Ding, Dawei; Dong, Bitao; Liang, Jin; Zhou, Han; Pang, Yuanchao; Ding, Shujiang

    2016-09-21

    In this work, a thinning process of hematite film accompanied by simultaneous titanium (Ti) doping has been demonstrated. Ti(4+) ion was incorporated into ultrathin Fe2O3 film by solvothermally etching a hematite film fabricated on titanium nanorod array substrate. As a consequence, the onset potential (Von) of oxygen evolution reaction for final ultrathin Ti-doped Fe2O3 film shifted toward cathodic substantially, a very low Von of 0.48 VRHE was realized, approximately 0.53 V cathodic shift of the hematite film. Working mechanisms were investigated from both kinetic and thermodynamic ways. The ultrathin Ti-doped Fe2O3 film exhibited reduced Tafel slope and higher generated photovoltage than the pristine Fe2O3 electrode. Moreover, the highly doped Fe2O3 resulted in significant reduction of charge-transfer resistance at the Fe2O3∥electrolyte interface. The drastic cathodic-shift Von is believed to be a result of combined factors including thermodynamic contribution, improved surface reaction kinetics, as well as facilitated charge transfer across bulk and interface.

  9. Toxicological investigations in the semiconductor industry: I. Studies on the acute oral toxicity of a complex mixture of waste products from the aluminium plasma etching process.

    PubMed

    Bauer, S; Wolff, I; Werner, N; Hoffmann, P; Herzschuh, R; Oemus, K; Rath, F W; Voigt, R

    1992-01-01

    In dry etching processes--one of the sources of potential exposure to toxic wastes in the semiconductor industry--complex mixtures of inorganic and organic compounds arise from reactions between feed stock gases (BCl3/Cl2), top layers (aluminium photoresist), and the carrier gas (N2). Two different fractions of the complex mixture--one an ethanolic solution (ES) and the other an insoluble liquid residue (LR)--were examined for acute oral toxicity in rats. Analytical data showed that the ethanol soluble fraction contained mainly inorganic compounds, whereas the residue contained various halogenated hydrocarbons. Neither death nor behavioral changes occurred after oral administration and observation up to 23 days. ES caused a lower mean arterial blood pressure in both sexes, increased P-R-intervals in male rats, and caused some mild biochemical and hematological alterations and changes in relative organ weights compared to the control groups. Exposure to LR influenced food and water intake, and caused a significant decrease in body weights, signs of polyurie, as well as changes in various relative organ weights and biochemical and hematological parameters. The blood pressure of the male animals fell and the heart rates of both sexes decreased. PMID:1386950

  10. Toxicological investigations in the semiconductor industry: I. Studies on the acute oral toxicity of a complex mixture of waste products from the aluminium plasma etching process

    SciTech Connect

    Bauer, S.; Wolff, I.; Werner, N.; Hoffmann, P.; Herzschuh, R.; Oemus, K.; Rath, F.W.; Voigt, R. )

    1992-05-01

    In dry etching processes--one of the sources of potential exposure to toxic wastes in the semiconductor industry--complex mixtures of inorganic and organic compounds arise from reactions between feed stock gases (BCl3/Cl2), top layers (aluminium photoresist), and the carrier gas (N2). Two different fractions of the complex mixture--one an ethanolic solution (ES) and the other an insoluble liquid residue (LR)--were examined for acute oral toxicity in rats. Analytical data showed that the ethanol soluble fraction contained mainly inorganic compounds, whereas the residue contained various halogenated hydrocarbons. Neither death nor behavioral changes occurred after oral administration and observation up to 23 days. ES caused a lower mean arterial blood pressure in both sexes, increased P-R-intervals in male rats, and caused some mild biochemical and hematological alterations and changes in relative organ weights compared to the control groups. Exposure to LR influenced food and water intake, and caused a significant decrease in body weights, signs of polyurie, as well as changes in various relative organ weights and biochemical and hematological parameters. The blood pressure of the male animals fell and the heart rates of both sexes decreased.

  11. Metallographic examination of TD-nickel base alloys. [thermal and chemical etching technique evaluation

    NASA Technical Reports Server (NTRS)

    Kane, R. D.; Petrovic, J. J.; Ebert, L. J.

    1975-01-01

    Techniques are evaluated for chemical, electrochemical, and thermal etching of thoria dispersed (TD) nickel alloys. An electrochemical etch is described which yielded good results only for large grain sizes of TD-nickel. Two types of thermal etches are assessed for TD-nickel: an oxidation etch and vacuum annealing of a polished specimen to produce an etch. It is shown that the first etch was somewhat dependent on sample orientation with respect to the processing direction, the second technique was not sensitive to specimen orientation or grain size, and neither method appear to alter the innate grain structure when the materials were fully annealed prior to etching. An electrochemical etch is described which was used to observe the microstructures in TD-NiCr, and a thermal-oxidation etch is shown to produce better detail of grain boundaries and to have excellent etching behavior over the entire range of grain sizes of the sample.

  12. On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Miller, Eric L.; Dudenhoefer, James E.

    1989-01-01

    The signal distortion inherent to pressure transmission lines in free-piston Stirling engine research is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving the helium-charged free-piston Stirling engines. The underdamped flow regime is described, the primary resonance frequency is derived, and the pressure phase and amplitude distortion are discussed. The scope and limitation of the dynamic response analysis are considered.

  13. Experiment and Results on Plasma Etching of SRF cavities

    SciTech Connect

    Upadhyay, Janardan; Im, Do; Peshl, J.; Vuskovic, Leposova; Popovic, Svetozar; Valente, Anne-Marie; Phillips, H. Lawrence

    2015-09-01

    The inner surfaces of SRF cavities are currently chemically treated (etched or electropolished) to achieve the state of the art RF performance. We designed an apparatus and developed a method for plasma etching of the inner surface for SRF cavities. The process parameters (pressure, power, gas concentration, diameter and shape of the inner electrode, temperature and positive dc bias at inner electrode) are optimized for cylindrical geometry. The etch rate non-uniformity has been overcome by simultaneous translation of the gas point-of-entry and the inner electrode during the processing. A single cell SRF cavity has been centrifugally barrel polished, chemically etched and RF tested to establish a baseline performance. This cavity is plasma etched and RF tested afterwards. The effect of plasma etching on the RF performance of this cavity will be presented and discussed.

  14. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    SciTech Connect

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  15. ECR, ICP, and RIE plasma etching of GaN

    SciTech Connect

    Shul, R.J.; McClellan, G.B.; Rieger, D.J.; Hafich, M.J.

    1996-06-01

    The group III-nitrides continue to generate interest due to their wide band gaps and high dielectric constants. These materials have made significant impact on the compound semiconductor community as blue and ultraviolet light emitting diodes (LEDs). Realization of more advanced devices; including lasers and high temperature electronics, requires dry etch processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {mu}m/min. In this paper, we compare electron cyclotron resonance (ECR), inductively coupled plasma (ICP), and reactive ion etch (RIE) etch results for GaN. These are the first ICP etch results reported for GaN. We also report ECR etch rates for GaN as a function of growth technique.

  16. LDRD final report : on the development of hybrid level-set/particle methods for modeling surface evolution during feature-scale etching and deposition processes.

    SciTech Connect

    McBride, Cory L.; Schmidt, Rodney Cannon; Musson, Lawrence Cale

    2005-01-01

    Two methods for creating a hybrid level-set (LS)/particle method for modeling surface evolution during feature-scale etching and deposition processes are developed and tested. The first method supplements the LS method by introducing Lagrangian marker points in regions of high curvature. Once both the particle set and the LS function are advanced in time, minimization of certain objective functions adjusts the LS function so that its zero contour is in closer alignment with the particle locations. It was found that the objective-minimization problem was unexpectedly difficult to solve, and even when a solution could be found, the acquisition of it proved more costly than simply expanding the basis set of the LS function. The second method explored is a novel explicit marker-particle method that we have named the grid point particle (GPP) approach. Although not a LS method, the GPP approach has strong procedural similarities to certain aspects of the LS approach. A key aspect of the method is a surface rediscretization procedure--applied at each time step and based on a global background mesh--that maintains a representation of the surface while naturally adding and subtracting surface discretization points as the surface evolves in time. This method was coded in 2-D, and tested on a variety of surface evolution problems by using it in the ChISELS computer code. Results shown for 2-D problems illustrate the effectiveness of the method and highlight some notable advantages in accuracy over the LS method. Generalizing the method to 3D is discussed but not implemented.

  17. Laser-assisted dry etching of III-nitride wide band gap semiconductor materials

    NASA Astrophysics Data System (ADS)

    Leonard, Robert Tyler

    Laser assisted dry etching is a materials processing technique capable of producing highly anisotropic etch features with precise etch depth control and little contamination. The technique is simple: laser radiation is combined with a gaseous chemical etchant to remove material in pattern selected regions. The advantages of laser etching include the removal of etch products with photonic energy instead of ion bombardment, potential of projected patterning to combine growth and etching in situ without exposure to air, production of distinct sidewall etch features for device structures, and precise control of etching with a highly directional pulsed laser energy source. The use of pulsed laser radiation allows for pulsed etch depth control, ultimately resulting in atomic layer control. Laser assisted dry HCl etching of GaN, AlGaN and InGaN optical device materials was first demonstrated in our laboratory at North Carolina State University in a modified UHV vacuum chamber and ArF (193nm) excimer laser. Effective masking materials of Al and SiOsb2 were determined to be resistant to laser heating and HCl environment for laser etching. The process variables of laser intensity and HCl pressure were found to be dominant with the necessary condition that no etching occurs without both the excimer laser and HCl present. Successful laser etching of GaN, AlGaN, and InGaN was demonstrated indicating that deep etch features with distinct sidewall features are possible with this technique. Laser etching of a III-Nitride quantum well double heterostructure resulted in no degradation of the photoluminescence response. Also, reduction of etch damage with laser etching may be possible in comparison to ion etching. Finally, a proposed model for the etching mechanism includes the photothermal release of nitrogen from the GaN surface resulting in a Ga-rich surface which is removed by the HCl etchant.

  18. Influence of track-etching on polycarbonate membrane permittivity

    NASA Astrophysics Data System (ADS)

    Allaeys, J.-F.; Marcilhac, B.; Mage, J.-C.

    2007-06-01

    The complex dielectric permittivity of track-etched polycarbonate (PC) membranes is measured and compared with raw polymer membranes. Membranes at different steps of the track-etching process are compared. Dielectric loss is a key factor for microwave nanowired substrate devices, and better knowledge of the materials is necessary for choosing the most suited polymer for applications. Our experimental data on track-etched and raw PC are similar, and the PC dielectric loss at every track-etching step is lower than the raw polyimide dielectric loss.

  19. Multiple-mask chemical etching

    NASA Technical Reports Server (NTRS)

    Cannon, D. L.

    1969-01-01

    Multiple masking techniques use lateral etching to reduce the total area of the high etch-rate oxide exposed to the chemical etchant. One method uses a short-term etch to remove the top layer from the silicon oxide surface, another acts before the top layer is grown.

  20. Etching fission tracks in zircons

    USGS Publications Warehouse

    Naeser, C.W.

    1969-01-01

    A new technique has been developed whereby fission tracks can be etched in zircon with a solution of sodium hydroxide at 220??C. Etching time varied between 15 minutes and 5 hours. Colored zircon required less etching time than the colorless varieties.

  1. Systematically controlling Kapitza conductance via chemical etching

    NASA Astrophysics Data System (ADS)

    Duda, John C.; Hopkins, Patrick E.

    2012-03-01

    We measure the thermal interface conductance between thin aluminum films and silicon substrates via time-domain thermoreflectance from 100 to 300 K. The substrates are chemically etched prior to aluminum deposition, thereby offering a means of controlling interface roughness. We find that conductance can be systematically varied by manipulating roughness. In addition, transmission electron microscopy confirms the presence of a conformal oxide for all roughnesses, which is then taken into account via a thermal resistor network. This etching process provides a robust technique for tuning the efficiency of thermal transport while alleviating the need for laborious materials growth and/or processing.

  2. Advanced deep reactive-ion etching technology for hollow microneedles for transdermal blood sampling and drug delivery.

    PubMed

    Liu, Yufei; Eng, Pay F; Guy, Owen J; Roberts, Kerry; Ashraf, Huma; Knight, Nick

    2013-06-01

    Using an SPTS Technologies Ltd. Pegasus deep reactive-ion etching (DRIE) system, an advanced two-step etching process has been developed for hollow microneedles in applications of transdermal blood sampling and drug delivery. Because of the different etching requirements of both narrow deep hollow and large open cavity, hollow etch and cavity etch steps have been achieved separately. This novel two-step etching process is assisted with a bi-layer etching mask. Results show that the etch rate of silicon during this hollow etch step was about 7.5 microm/min and the etch rate of silicon during this cavity etch step was about 8-10 microm/min, using the coil plasma etching power between 2.0 and 2.8 kW. Especially for the microneedle bores etch, the deeper it etched, the slower the etch rate was. The microneedle bores have successfully been obtained 75-150 microm in inner diametre and 700-1000 microm long with high aspect ratio DRIE, meanwhile, the vertical sidewall structures have been achieved with the high etch load exposed area over 70% for the cavity etch step. PMID:24046906

  3. Dry-wet digital etching of Ge1-xSnx

    NASA Astrophysics Data System (ADS)

    Shang, Colleen K.; Wang, Vivian; Chen, Robert; Gupta, Suyog; Huang, Yi-Chiau; Pao, James J.; Huo, Yijie; Sanchez, Errol; Kim, Yihwan; Kamins, Theodore I.; Harris, James S.

    2016-02-01

    The development of a precise micromachining process for Ge1-xSnx has the potential to enable both the fabrication and optimization of Ge1-xSnx-based devices in photonics and microelectromechanical systems. We demonstrate a digital etching scheme for Ge0.922Sn0.078 based on a two-stage, highly selective CF4 plasma dry etch and HCl wet etch. Using X-Ray Reflectivity, we show consistent etch control as low as 1.5 nm per cycle, which is defined as one dry etch step followed by one wet etch step. The etch rate increases to 3.2 nm per cycle for a longer dry etch time due to physical sputtering contributions, accompanied by an increase in RMS surface roughness. By operating within a regime with minimal sputtering, we demonstrate that good digital etch depth control and surface quality can be achieved using this technique.

  4. On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

    NASA Technical Reports Server (NTRS)

    Miller, Eric L.; Dudenhoefer, James E.

    1989-01-01

    In free piston Stirling engine research the integrity of both amplitude and phase of the dynamic pressure measurements is critical to the characterization of cycle dynamics and thermodynamics. It is therefore necessary to appreciate all possible sources of signal distortion when designing pressure measurement systems for this type of research. The signal distortion inherent to pressure transmission lines is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving helium-charged free piston Stirling engines. The scope and limitations of the dynamic response analysis are considered.

  5. Correction for etch proximity: new models and applications

    NASA Astrophysics Data System (ADS)

    Granik, Yuri

    2001-09-01

    Short-range etch proximity effects increase intra-die CD variability and degrade the IC performance and yield. Tight control of the etch bias is an increasingly critical factor in realizing the ITRS technology nodes. The 2000 technology nodes revision added a new category, the post-etch 'physical' gate length metric, that is 9 - 17% smaller than 'in-resist' gate length. We present new etch proximity correction methods and models designed to reduce negative impact of etch-induced CD variability and increase uniformity of the controlled over- etching. Resolution Enhancement Technologies (RET) design correction methods typically employ 'lumped' process models. We found that an alternative methodology based upon separation of the process factors and the related models may yield better accuracy, performance, and better suit the design and process optimization flows. The contributions from the reticle, the optics, the wafer, and etch are individually determined and then used either separately or in aggregation for the most flexible and optimum correction of their respective contributions. The etch corrections are based on the Variable Etch Bias model (VEB model). This semi-empirical model requires experimental CD information to be collected from the test patterns under fixed process conditions (point-process model). It demonstrates excellent fit to the early experimental CD-SEM data gathered to date, which spans a variety of layout features and process conditions. The VEB model works in conjunction with CalibreR software system's Variable Threshold Resist-Extended (VTR-E) model, however the etching is modeled separately from the optics and the resist processing. This yields better understanding and more accurate explanation of the experiments than those that are produced by the 'lumped' process modeling. The VEB model explains etch- induced bias in terms of the following three proximity characteristics or variables: effective trench width (or pattern separation), pattern

  6. Physics and chemistry of complex oxide etching and redeposition control

    NASA Astrophysics Data System (ADS)

    Margot, Joëlle

    2012-10-01

    Since its introduction in the 1970s, plasma etching has become the universal method for fine-line pattern transfer onto thin films and is anticipated to remain so in foreseeable future. Despite many success stories, plasma etching processes fail to meet the needs for several of the newest materials involved in advanced devices for photonic, electronic and RF applications like ferroelectrics, electro-optic materials, high-k dielectrics, giant magnetoresistance materials and unconventional conductors. In this context, the work achieved over the last decade on the etching of multicomponent oxides thin films such as barium strontium titanate (BST), strontium titanate (STO) and niobate of calcium and barium (CBN) will be reviewed. These materials present a low reactivity with usual etching gases such as fluorinated and chlorinated gases, their etching is mainly governed by ion sputtering and reactive gases sometimes interact with surface materials to form compounds that inhibit etching. The etching of platinum will also be presented as an example of unconventional conductor materials for which severe redeposition limits the achievable etching quality. Finally, it will be shown how simulation can help to understand the etching mechanisms and to define avenues for higher quality patterning.

  7. Isotropic plasma etching of Ge Si and SiNx films

    DOE PAGES

    Henry, Michael David; Douglas, Erica Ann

    2016-08-31

    This study reports on selective isotropic dry etching of chemically vapor deposited (CVD) Ge thin film, release layers using a Shibaura chemical downstream etcher (CDE) with NF3 and Ar based plasma chemistry. Relative etch rates between Ge, Si and SiNx are described with etch rate reductions achieved by adjusting plasma chemistry with O2. Formation of oxides reducing etch rates were measured for both Ge and Si, but nitrides or oxy-nitrides created using direct injection of NO into the process chamber were measured to increase Si and SiNx etch rates while retarding Ge etching.

  8. Nanoscale dry etching of germanium by using inductively coupled CF4 plasma

    NASA Astrophysics Data System (ADS)

    Shim, Kyu-Hwan; Yang, Ha Yong; Kil, Yeon-Ho; Yang, Hyeon Deok; Yang, Jong-Han; Hong, Woong-Ki; Kang, Sukill; Jeong, Tae Soo; Kim, Taek Sung

    2012-08-01

    The nanoscale dry etching of germanium was investigated by using inductively coupled CF4 plasma and electron-beam lithography. The optimal dose of PMMA as E-beam lithography resist was ˜200 mC/cm2. When ICP Power was 200W, CF4 gas flow rate was 40 sccm, and process pressure was 20 mTorr, it had a smooth surface and good etch rate. The etching selectivity of Ge wafer to PMMA resist was as low as ˜1.5. Various sub-100 nm dry-etching patterns have been obtained. SEM pictures showed good profile qualities with a smooth etching sidewall and ultrasmall etching features.

  9. Pulsed plasma etching for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Economou, Demetre J.

    2014-07-01

    Power-modulated (pulsed) plasmas have demonstrated several advantages compared to continuous wave (CW) plasmas. Specifically, pulsed plasmas can result in a higher etching rate, better uniformity, and less structural, electrical or radiation (e.g. vacuum ultraviolet) damage. Pulsed plasmas can also ameliorate unwanted artefacts in etched micro-features such as notching, bowing, micro-trenching and aspect ratio dependent etching. As such, pulsed plasmas may be indispensable in etching of the next generation of micro-devices with a characteristic feature size in the sub-10 nm regime. This work provides an overview of principles and applications of pulsed plasmas in both electropositive (e.g. argon) and electronegative (e.g. chlorine) gases. The effect of pulsing the plasma source power (source pulsing), the electrode bias power (bias pulsing), or both source and bias power (synchronous pulsing), on the time evolution of species densities, electron energy distribution function and ion energy and angular distributions on the substrate is discussed. The resulting pulsed plasma process output (etching rate, uniformity, damage, etc) is compared, whenever possible, to that of CW plasma, under otherwise the same or similar conditions.

  10. In-situ diagnostics and characterization of etch by-product deposition on chamber walls during halogen etching of silicon

    NASA Astrophysics Data System (ADS)

    Rastgar, Neema; Sriraman, Saravanapriyan; Marsh, Ricky; Paterson, Alex

    2014-10-01

    Plasma etching is a critical technology for nanoelectronics fabrication, but the use of a vacuum chamber limits the number of in-situ, real-time diagnostics measurements that can be performed during an etch process. Byproduct deposition on chamber walls during etching can affect the run-to-run performance of an etch process if there is build-up or change of wall characteristics with time. Knowledge of chamber wall evolution and the composition of wall-deposited films are critical to understanding the performance of plasma etch processes, and an in-situ diagnostics measurement is useful for monitoring the chamber walls in real time. We report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to perform in-situ diagnostics of a vacuum chamber's walls during plasma etching. Using ATR-FTIR, we are able to monitor the relative thickness and makeup of chamber wall deposits in real time. We then use this information to develop a chamber wall cleaning process in order to maintain reproducible etching conditions from wafer to wafer. In particular, we report mid-IR (4000-650 cm-1) absorption spectra of chamber wall-deposited silicon byproducts formed during halogen etching of silicon wafers.

  11. Focused electron-beam-induced etching of silicon dioxide

    SciTech Connect

    Randolph, S.J.; Fowlkes, J.D.; Rack, P.D.

    2005-08-01

    Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO{sub 2} matrix, and subsequently rate limited by XeF{sub 2} availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO{sub 2} to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

  12. Focused electron-beam-induced etching of silicon dioxide

    NASA Astrophysics Data System (ADS)

    Randolph, S. J.; Fowlkes, J. D.; Rack, P. D.

    2005-08-01

    Focused electron-beam (FEB)-induced etching of silicon dioxide with xenon difluoride has been investigated as a selective nanoscale etching technique. In order to gain an understanding of the parameters that control etch rate and etch efficiency, the effects of beam current, beam energy, and scan rate conditions on the FEB process were examined. High etch rates were obtained for low beam energy, high beam current, and high scan rates. Experimental results also indicated that the FEB etch process is governed by the electron-stimulated desorption of oxygen from the SiO2 matrix, and subsequently rate limited by XeF2 availability. Based on experimental evidence and existing literature, a simple, two-step model was introduced to qualitatively describe the etch mechanism. The model involves a cyclical process, which is initiated by the reduction of a surface layer of SiO2 to elemental silicon. The exposed silicon surface is then removed by a chemical-mediated etch reaction.

  13. A paradigm shift in patterning foundation from frequency multiplication to edge-placement accuracy: a novel processing solution by selective etching and alternating-material self-aligned multiple patterning

    NASA Astrophysics Data System (ADS)

    Han, Ting; Liu, Hongyi; Chen, Yijian

    2016-03-01

    Overlay errors, cut/block and line/space critical-dimension (CD) variations are the major sources of the edge-placement errors (EPE) in the cut/block patterning processes of complementary lithography when IC technology is scaled down to sub-10nm half pitch (HP). In this paper, we propose and discuss a modular technology to reduce the EPE effect by combining selective etching and alternating-material (dual-material) self-aligned multiple patterning (altSAMP) processes. Preliminary results of altSAMP process development and material screening experiment are reported and possible material candidates are suggested. A geometrical cut-process yield model considering the joint effect of overlay errors, cut-hole and line CD variations is developed to analyze its patterning performance. In addition to the contributions from the above three process variations, the impacts of key control parameters (such as cut-hole overhang and etching selectivity) on the patterning yield are examined. It is shown that the optimized altSAMP patterning process significantly improves the patterning yield compared with conventional SAMP processes, especially when the half pitch of device patterns is driven down to 7 nm and below.

  14. Atomic precision etch using a low-electron temperature plasma

    NASA Astrophysics Data System (ADS)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2016-03-01

    Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

  15. Optical diagnostic instrument for monitoring etch uniformity during plasma etching of polysilicon in a chlorine-helium plasma

    SciTech Connect

    Hareland, W.A.; Buss, R.J.

    1993-06-01

    Nonuniform etching is a serious problem in plasma processing of semiconductor materials and has important consequences in the quality and yield of microelectronic components. In many plasmas, etching occurs at a faster rate near the periphery of the wafer, resulting in nonuniform removal of specific materials over the wafer surface. This research was to investigate in situ optical diagnostic techniques for monitoring etch uniformity during plasma processing of microelectronic components. We measured 2-D images of atomic chlorine at 726 nm in a chlorine-helium plasma during plasma etching of polysilicon in a parallel-plate plasma etching reactor. The 3-D distribution of atomic chlorine was determined by Abel inversion of the plasma image. The experimental results showed that the chlorine atomic emission intensity is at a maximum near the outer radius of the plasma and decreases toward the center. Likewise, the actual etch rate, as determined by profilometry on the processed wafer, was approximately 20% greater near the edge of the wafer than at its center. There was a direct correlation between the atomic chlorine emission intensity and the etch rate of polysilicon over the wafer surface. Based on these analyses, 3-D imaging would be a useful diagnostic technique for in situ monitoring of etch uniformity on wafers.

  16. Porous silicon formation during Au-catalyzed etching

    SciTech Connect

    Algasinger, Michael; Bernt, Maximilian; Koynov, Svetoslav; Stutzmann, Martin

    2014-04-28

    The formation of “black” nano-textured Si during the Au-catalyzed wet-chemical etch process was investigated with respect to photovoltaic applications. Cross-sectional scanning electron microscopy (SEM) images recorded at different stages of the etch process exhibit an evolution of a two-layer structure, consisting of cone-like Si hillocks covered with a nano-porous Si (np-Si) layer. Optical measurements confirm the presence of a np-Si phase which appears after the first ∼10 s of the etch process and continuously increases with the etch time. Furthermore, the etch process was investigated on Si substrates with different doping levels (∼0.01–100 Ω cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 Ω cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of “black” Si on various Si substrates, which is of significant interest for photovoltaic applications.

  17. Technique for etching monolayer and multilayer materials

    DOEpatents

    Bouet, Nathalie C. D.; Conley, Raymond P.; Divan, Ralu; Macrander, Albert

    2015-10-06

    A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi.sub.2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF.sub.3, Cl.sub.2, and O.sub.2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.

  18. Surface and thin film studies of the etching of molybdenum by xenon difluoride

    NASA Astrophysics Data System (ADS)

    Celik, Ozgur

    The controlled etching of micro/nano structures is essential for a variety of technological applications, including microelectromechanical systems (MEMS) fabrication. XeF2 is an isotropic and highly selective etching gas used to remove semiconductors and metals in the fabrication of MEMS and other devices. While the kinetics of XeF2 etching Si has been widely documented, XeF2 etching of metals is not widely understood. For better process control and device quality, it is important to understand the etching mechanism at the molecular level. In this work, we explore the surface and gas phase chemistry of XeF2 etching Mo films. Studies on the general characteristics of etching Mo blanket films were carried out on 1000AMo/475ASiO2/100ANi/glass samples at different sample temperatures and etchant pressures in a standalone etching chamber. They were analyzed ex-situ by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) for investigating morphology and chemical composition of the surfaces after etchings, respectively. Rutherford back scattering (RBS) was used to measure the thickness of the films and the depth profile of near-surface species after etching. Downstream mass spectrometry was used to identify the volatile products of the etching process. The composition and chemical state of the etched surface (reaction layer) is further investigated by in-vacuo etching and XPS analysis experiments using 3750AMo/quartz samples in an integrated etching/analysis system. The XPS studies have clarified issues on: (i) the thickness and chemical composition of the reaction layer during etching, (ii) the effects of the surface native oxides and adventitious hydrocarbons on the initiation and progress of etching, (iii) the re-deposition of etched products. Post-etching thermal processing and XPS analysis studies were performed to investigate the chemical composition of residues left after etching. Kinetics of etching blanket Mo films was investigated using total

  19. Aspect-ratio-dependent etching of polymers as interlayer dielectrics

    NASA Astrophysics Data System (ADS)

    Kim, Gusung

    2000-08-01

    The reactive ion etching of the polymer has been studied in CF4-O2, SF6, and N2 plasmas to understand the contributions of aspect-ratio dependent etching (ARDE), an anisotropic etch profiles, and the etch rate for one of low-k polymers, Divinyl bis-benzocyclobutene (BCB, silicon containing spin-on polymer). A new experimental process (Type B) was implemented to determine the ARDE in which the AR remains constant during the entire experiment. These samples showed the uniform etch rate for all trenches. However, in conventional structure (Type A), using a SiO2 hardmask for patterning, ARDE phenomena can be observed. In the range of 30--35% CF4 in O2, BCB shows the maximum etch rate, and this coincides with the maximum in the oxygen concentration. Complete anisotropic profiles can be obtained at low pressure where the fluorine atom concentration is low. The highest etch rates are achieved at the higher pressures where fluorine and oxygen atom concentrations are high, but with an increase in the amount of profile tapering in Type A. In Type B samples, etching gives increased undercutting and bowing with an increase in pressure. At low pressure, the sidewall profile is vertical regardless of the aspect ratio of the pattern. No oxide is exposed to the CF4-O2 plasma and undercutting occurs with an increase of fluorine concentration. In large trenches, polymer residue and micromasking phenomena were observed in both cases. Specifically, the surface roughness of etched BCB in CF 4-O2 was much higher than in SF6 and N2. Lateral etching of the BCB, mask erosion and faceting of the hardmask were more prominently observed with SF6. SF6 produces a very clean surface and no residue at the bottom of a trench. In N2 plasma, the etch rate of BCB is very low due to physical ion bombardment and trenches are formed by mask erosion and micro-trenching.

  20. Anisotropic Ta{sub 2}O{sub 5} waveguide etching using inductively coupled plasma etching

    SciTech Connect

    Muttalib, Muhammad Firdaus A. Chen, Ruiqi Y.; Pearce, Stuart J.; Charlton, Martin D. B.

    2014-07-01

    Smooth and vertical sidewall profiles are required to create low loss rib and ridge waveguides for integrated optical device and solid state laser applications. In this work, inductively coupled plasma (ICP) etching processes are developed to produce high quality low loss tantalum pentoxide (Ta{sub 2}O{sub 5}) waveguides. A mixture of C{sub 4}F{sub 8} and O{sub 2} gas are used in combination with chromium (Cr) hard mask for this purpose. In this paper, the authors make a detailed investigation of the etch process parameter window. Effects of process parameters such as ICP power, platen power, gas flow, and chamber pressure on etch rate and sidewall slope angle are investigated. Chamber pressure is found to be a particularly important factor, which can be used to tune the sidewall slope angle and so prevent undercut.

  1. Selective Etching of Semiconductor Glassivation

    NASA Technical Reports Server (NTRS)

    Casper, N.

    1982-01-01

    Selective etching technique removes portions of glassivation on a semi-conductor die for failure analysis or repairs. A periodontal needle attached to a plastic syringe is moved by a microprobe. Syringe is filled with a glass etch. A drop of hexane and vacuum pump oil is placed on microcircuit die and hexane is allowed to evaporate leaving a thin film of oil. Microprobe brings needle into contact with area of die to be etched.

  2. Consideration of VT5 etch-based OPC modeling

    NASA Astrophysics Data System (ADS)

    Lim, ChinTeong; Temchenko, Vlad; Kaiser, Dieter; Meusel, Ingo; Schmidt, Sebastian; Schneider, Jens; Niehoff, Martin

    2008-03-01

    Including etch-based empirical data during OPC model calibration is a desired yet controversial decision for OPC modeling, especially for process with a large litho to etch biasing. While many OPC software tools are capable of providing this functionality nowadays; yet few were implemented in manufacturing due to various risks considerations such as compromises in resist and optical effects prediction, etch model accuracy or even runtime concern. Conventional method of applying rule-based alongside resist model is popular but requires a lot of lengthy code generation to provide a leaner OPC input. This work discusses risk factors and their considerations, together with introduction of techniques used within Mentor Calibre VT5 etch-based modeling at sub 90nm technology node. Various strategies are discussed with the aim of better handling of large etch bias offset without adding complexity into final OPC package. Finally, results were presented to assess the advantages and limitations of the final method chosen.

  3. A geometric etch-stop technology for bulk micromachining

    NASA Astrophysics Data System (ADS)

    Amir Parviz, Babak; Najafi, Khalil

    2001-05-01

    This paper describes a new fabrication method for the simultaneous creation of multi-level single-crystalline silicon structures, each with a different thickness. The method combines deep dry etching and wet anisotropic etching of silicon in order to avoid multiple back-side alignment steps and timed etches. The levels are defined in a single lithographic step from the front side. The fabrication involves etching of deep trenches from the front side of the wafer followed by a refill and etch back process. The final structure is defined by maskless wet etching of the bulk silicon. The progress of the anisotropic wet etch is impeded by the geometric pattern at the bottom of the trenches, and thus structures with various thickness ranging from ten to a few hundred micrometres can be implemented. The effect of various design parameters, such as trench geometry, refill material and reactive ion etching lag, are discussed and design rules are established. The capabilities of the method are demonstrated by the fabrication of a number of devices, such as 1200×1200×3.5 µm diaphragms supported by a 40 µm thick rim and (1800×10×3 µm) embedded hot-wire anemometers suspended by a 0.2 µm thick dielectric bridge.

  4. Layout decomposition and synthesis for a modular technology to solve the edge-placement challenges by combining selective etching, direct stitching, and alternating-material self-aligned multiple patterning processes

    NASA Astrophysics Data System (ADS)

    Liu, Hongyi; Han, Ting; Zhou, Jun; Chen, Yijian

    2016-03-01

    To overcome the prohibitive barriers of edge-placement errors (EPE) in the cut/block/via step of complementary lithography, we propose a modular patterning approach by combining layout stitching, selective etching, and alternating-material self-aligned multiple patterning (altSAMP) processes. In this patterning approach, altSAMP is used to create line arrays with two materials alternatively which allow a highly selective etching process to remove one material without attacking the other, therefore more significant EPE effect can be tolerated in line-cutting step. With no need of connecting vias, the stitching process can form 2-D features by directly stitching two components of patterns together to create 2-D design freedom as well as multiple-CD/pitch capability. By adopting this novel approach, we can potentially achieve higher processing yield and more 2-D design freedom for continuous IC scaling down to 5 nm. We developed layout decomposition and synthesis algorithms for critical layers, and the fin/gate/metal layer from NSCU open cell library is used to test the proposed algorithms.

  5. Disilane-based cyclic deposition/etch of Si, Si:P and Si1-yCy:P layers: I. The elementary process steps

    NASA Astrophysics Data System (ADS)

    Hartmann, J. M.; Benevent, V.; Barnes, J. P.; Veillerot, M.; Deguet, C.

    2013-02-01

    We have benchmarked the 550 °C, 20 Torr growth of Si:P and Si1-yCy:P using SiH4 and Si2H6. P segregation has prevented us from reaching P+ ion concentrations in Si higher than a few 1019 cm-3 using SiH4; the resulting surface ‘poisoning’ led to a severe growth rate reduction. Meanwhile, [P+] increased linearly with the phosphine flow when using Si2H6 as the Si precursor; values as high as 1.7 × 1020 cm-3 were obtained. The Si:P growth rate using Si2H6 was initially stable then increased as the PH3 flow increased. Mono-methylsilane flows 6.5-10 times higher were needed with Si2H6 than with SiH4 to reach the same substitutional C concentrations in intrinsic Si1-yCy layers ([C]subst. up to 1.9%). Growth rates were approximately six times higher with Si2H6 than with SiH4, however. 30 nm thick Si1-yCy layers became rough as [C]subst. exceeded 1.6% (formation of increasing numbers of islands). We have also studied the structural and electrical properties of ‘low’ and ‘high’ C content Si1-yCy:P layers (˜ 1.5 and 1.8%, respectively) grown with Si2H6. Adding significant amounts of PH3 led to a reduction of the tensile strain in the films. This was due to the incorporation of P atoms (at the expense of C atoms) in the substitutional sites of the Si matrix. Si1-yCy:P layers otherwise became rough as the PH3 flow increased. Resistivities lower than 1 mΩ cm were nevertheless associated with those Si1-yCy:P layers, with P atomic concentrations at most 3.9 × 1020 cm-3. Finally, we have quantified the beneficial impact of adding GeH4 to HCl for the low-temperature etching of Si. Etch rates 12-36 times higher with HCl + GeH4 than with pure HCl were achieved at 20 Torr. Workable etch rates close to 1 nm min-1 were obtained at 600 °C (versus 750 °C for pure HCl), enabling low-temperature cyclic deposition/etch strategies for the selective epitaxial growth of Si, Si:P and Si1-yCy:P layers on patterned wafers.

  6. Dry etching technologies for the advanced binary film

    NASA Astrophysics Data System (ADS)

    Iino, Yoshinori; Karyu, Makoto; Ita, Hirotsugu; Yoshimori, Tomoaki; Azumano, Hidehito; Muto, Makoto; Nonaka, Mikio

    2011-11-01

    ABF (Advanced Binary Film) developed by Hoya as a photomask for 32 (nm) and larger specifications provides excellent resistance to both mask cleaning and 193 (nm) excimer laser and thereby helps extend the lifetime of the mask itself compared to conventional photomasks and consequently reduces the semiconductor manufacturing cost [1,2,3]. Because ABF uses Ta-based films, which are different from Cr film or MoSi films commonly used for photomask, a new process is required for its etching technology. A patterning technology for ABF was established to perform the dry etching process for Ta-based films by using the knowledge gained from absorption layer etching for EUV mask that required the same Ta-film etching process [4]. Using the mask etching system ARES, which is manufactured by Shibaura Mechatronics, and its optimized etching process, a favorable CD (Critical Dimension) uniformity, a CD linearity and other etching characteristics were obtained in ABF patterning. Those results are reported here.

  7. High temperature reactive ion etching of iridium thin films with aluminum mask in CF4/O2/Ar plasma

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Pin; Lisker, Marco; Kalkofen, Bodo; Burte, Edmund P.

    2016-08-01

    Reactive ion etching (RIE) technology for iridium with CF4/O2/Ar gas mixtures and aluminum mask at high temperatures up to 350 °C was developed. The influence of various process parameters such as gas mixing ratio and substrate temperature on the etch rate was studied in order to find optimal process conditions. The surface of the samples after etching was found to be clean under SEM inspection. It was also shown that the etch rate of iridium could be enhanced at higher process temperature and, at the same time, very high etching selectivity between aluminum etching mask and iridium could be achieved.

  8. Energy dispersive X-ray spectroscopy analysis of Si sidewall surface etched by deep-reactive ion etching

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Nishioka, Kunio; Sato, Mina

    2016-06-01

    We investigated the composition of a passivation film on a sidewall etched by deep-reactive ion etching (RIE) using SF6/O2 and C4F8 plasma, by energy-dispersive X-ray (EDX) spectroscopy. It was found that the compositions of carbon and fluorine in the passivation film on the etched sidewall depend on the width and depth of the etched trench. It is important to understand both the plasma behavior and the passivation film composition to carry out fabrication by deep-RIE. We consider that these results of the EDX analysis of an etched sidewall will be useful for understanding plasma behavior in order to optimize the process conditions of deep-RIE.

  9. Structural and magnetic etch damage in CoFeB

    SciTech Connect

    Krayer, L.; Lau, J. W.; Kirby, B. J.

    2014-05-07

    A detailed understanding of the interfacial properties of thin films used in magnetic media is critical for the aggressive component scaling required for continued improvement in storage density. In particular, it is important to understand how common etching and milling processes affect the interfacial magnetism. We have used polarized neutron reflectometry and transmission electron microscopy to characterize the structural and magnetic properties of an ion beam etched interface of a CoFeB film. We found that the etching process results in a sharp magnetic interface buried under a nanometer scale layer of non-magnetic, compositionally distinct material.

  10. Group-III Nitride Etch Selectivity in BCl(3)/Cl(2) ICP Plasmas

    SciTech Connect

    Abernathy, C.R.; Han, J.; Hong, J.; Lester, L.F.; Pearton, S.J.; Shul, R.J.; Willison, C.G.; Zhang, L.

    1998-12-09

    Patterning the group-IH nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used almost exclusively to pattern these films. The use of high-density plasma etch systems, including inductively coupled plasmas (ICP), has resulted in relatively high etch rates (often greater than 1.0 pmhnin) with anisotropic profiles and smooth etch morphologies. However, the etch mechanism is often dominated by high ion bombardment energies which can minimize etch selectivity. The use of an ICP-generated BCl~/C12 pkyma has yielded a highly versatile GaN etch process with rates ranging from 100 to 8000 A/rnin making this plasma chemistry a prime candidate for optimization of etch selectivity. In this study, we will report ICP etch rates and selectivities for GaN, AIN, and InN as a function of BCl~/Clz flow ratios, cathode rf-power, and ICP-source power. GaN:InN and GaN:AIN etch selectivities were typically less than 7:1 and showed the strongest dependence on flow ratio. This trend maybe attributed to faster GaN etch rates observed at higher concentrations of atomic Cl which was monitored using optical emission spectroscopy (OES). ~E~~~~f:~ INTRODUCTION DEC j 4898 Etch selectivi

  11. Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas

    NASA Astrophysics Data System (ADS)

    Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M.; Economou, Demetre J.

    2014-05-01

    Cl2, Br2, HBr, Br2/Cl2, and HBr/Cl2 feed gases diluted in Ar (50%-50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br2/Ar and HBr/Cl2/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF2, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl2/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to ⟨110⟩ cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

  12. Etch Profile Simulation Using Level Set Methods

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    Etching and deposition of materials are critical steps in semiconductor processing for device manufacturing. Both etching and deposition may have isotropic and anisotropic components, due to directional sputtering and redeposition of materials, for example. Previous attempts at modeling profile evolution have used so-called "string theory" to simulate the moving solid-gas interface between the semiconductor and the plasma. One complication of this method is that extensive de-looping schemes are required at the profile corners. We will present a 2D profile evolution simulation using level set theory to model the surface. (1) By embedding the location of the interface in a field variable, the need for de-looping schemes is eliminated and profile corners are more accurately modeled. This level set profile evolution model will calculate both isotropic and anisotropic etch and deposition rates of a substrate in low pressure (10s mTorr) plasmas, considering the incident ion energy angular distribution functions and neutral fluxes. We will present etching profiles of Si substrates in Ar/Cl2 discharges for various incident ion energies and trench geometries.

  13. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, Robert J.; Mayer, Steven T.; Tarte, Lisa A.

    1996-01-01

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment.

  14. Removal of field and embedded metal by spin spray etching

    DOEpatents

    Contolini, R.J.; Mayer, S.T.; Tarte, L.A.

    1996-01-23

    A process of removing both the field metal, such as copper, and a metal, such as copper, embedded into a dielectric or substrate at substantially the same rate by dripping or spraying a suitable metal etchant onto a spinning wafer to etch the metal evenly on the entire surface of the wafer. By this process the field metal is etched away completely while etching of the metal inside patterned features in the dielectric at the same or a lesser rate. This process is dependent on the type of chemical etchant used, the concentration and the temperature of the solution, and also the rate of spin speed of the wafer during the etching. The process substantially reduces the metal removal time compared to mechanical polishing, for example, and can be carried out using significantly less expensive equipment. 6 figs.

  15. Spectrometric analysis of process etching solutions of the photovoltaic industry--determination of HNO3, HF, and H2SiF6 using high-resolution continuum source absorption spectrometry of diatomic molecules and atoms.

    PubMed

    Bücker, Stefan; Acker, Jörg

    2012-05-30

    The surface of raw multicrystalline silicon wafers is treated with HF-HNO(3) mixtures in order to remove the saw damage and to obtain a well-like structured surface of low reflectivity, the so-called texture. The industrial production of solar cells requires a consistent level of texturization for tens of thousands of wafers. Therefore, knowing the actual composition of the etch bath is a key element in process control in order to maintain a certain etch rate through replenishment of the consumed acids. The present paper describes a novel approach to quantify nitric acid (HNO(3)), hydrofluoric acid (HF), and hexafluosilicic acid (H(2)SiF(6)) using a high-resolution continuum source graphite furnace absorption spectrometer. The concentrations of Si (via Si atom absorption at the wavelength 251.611 nm, m(0),(Si)=130 pg), of nitrate (via molecular absorption of NO at the wavelength 214.803 nm, [Formula: see text] ), and of total fluoride (via molecular absorption of AlF at the wavelength 227.46 nm, m(0,F)=13 pg) were measured against aqueous standard solutions. The concentrations of H(2)SiF(6) and HNO(3) are directly obtained from the measurements. The HF concentration is calculated from the difference between the total fluoride content, and the amount of fluoride bound as H(2)SiF(6). H(2)SiF(6) and HNO(3) can be determined with a relative uncertainty of less than 5% and recoveries of 97-103% and 96-105%, respectively. With regards to HF, acceptable results in terms of recovery and uncertainty are obtained for HF concentrations that are typical for the photovoltaic industry. The presented procedure has the unique advantage that the concentration of both, acids and metal impurities in etch solutions, can be routinely determined by a single analytical instrument. PMID:22608457

  16. Etching of oxynitride thin films using inductively coupled plasma

    SciTech Connect

    Kim, Byungwhan; Lee, Dukwoo; Kim, Nam Jung; Lee, Byung Teak

    2005-05-01

    In this study, silicon oxynitride (SiON) has been etched in a C{sub 2}F{sub 6} inductively coupled plasma. The process parameters examined include a radio frequency source power, bias power, pressure, and C{sub 2}F{sub 6} flow rate. For process optimization, a statistical experimental design was employed to investigate parameter effects under various plasma conditions. The etch rate increased almost linearly with increasing the source or bias power. Main effect analysis revealed that the etch rate is dominated by the source power. The C{sub 2}F{sub 6} flow rate exerted the least impact on both etch rate and profile angle. It was estimated that the C{sub 2}F{sub 6} effect is transparent only as the etchant is supplied sufficiently. Depending on the pressure levels, the etch rate varied in a complicated way. Parameter effects on the profile angle were very small and the profile angle varied between 83 deg. and 87 deg. for all etching experiments. In nearly all experiments, microtrenching was observed. The etch rate and profile angle, optimized at 1000 W source power, 30 W bias power, 6 mTorr pressure, and 60 sccm C{sub 2}F{sub 6} flow rate, are 434 nm/min and 86 deg., respectively.

  17. Laser etching of polymer masked leadframes

    NASA Astrophysics Data System (ADS)

    Ho, C. K.; Man, H. C.; Yue, T. M.; Yuen, C. W.

    1997-02-01

    A typical electroplating production line for the deposition of silver pattern on copper leadframes in the semiconductor industry involves twenty to twenty five steps of cleaning, pickling, plating, stripping etc. This complex production process occupies large floor space and has also a number of problems such as difficulty in the production of rubber masks and alignment, generation of toxic fumes, high cost of water consumption and sometimes uncertainty on the cleanliness of the surfaces to be plated. A novel laser patterning process is proposed in this paper which can replace many steps in the existing electroplating line. The proposed process involves the application of high speed laser etching techniques on leadframes which were protected with polymer coating. The desired pattern for silver electroplating is produced by laser ablation of the polymer coating. Excimer laser was found to be most effective for this process as it can expose a pattern of clean copper substrate which can be silver plated successfully. Previous working of Nd:YAG laser ablation showed that 1.06 μm radiation was not suitable for this etching process because a thin organic and transparent film remained on the laser etched region. The effect of excimer pulse frequency and energy density upon the removal rate of the polymer coating was studied.

  18. Chlorine-based plasma etching of GaN

    SciTech Connect

    Shul, R.J.; Briggs, R.D.; Pearton, S.J.; Vartuli, C.B.; Abernathy, C.R.; Lee, J.W.; Constantine, C.; Baratt, C.

    1997-02-01

    The wide band gap group-III nitride materials continue to generate interest in the semiconductor community with the fabrication of green, blue, and ultraviolet light emitting diodes (LEDs), blue lasers, and high temperature transistors. Realization of more advanced devices requires pattern transfer processes which are well controlled, smooth, highly anisotropic and have etch rates exceeding 0.5 {micro}m/min. The utilization of high-density chlorine-based plasmas including electron cyclotron resonance (ECR) and inductively coupled plasma (ICP) systems has resulted in improved GaN etch quality over more conventional reactive ion etch (RIE) systems.

  19. High-Density Plasma Etching of Group-III Nitride Films for Device Application

    SciTech Connect

    Baca, A.G.; Crawford, M.H.; Han, J.; Lester, L.F.; Pearton, S.J.; Ren, F.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.

    1999-02-17

    As III-V nitride device structures become more complicated and design rules shrink, well-controlled etch processes are necessary. Due to limited wet chemical etch results for the group-III nitrides, a significant amount of effort has been devoted to the development of dry etch processing. Dry etch development was initially focused on mesa structures where high etch rates, anisotropic profiles, smooth sidewalls, and equi-rate etching of dissimilar materials were required. For example, commercially available LEDs and laser facets for GaN-based laser diodes have been patterned using reactive ion etching (RIE). With the recent interest in high power, high temperature electronic devices, etch characteristics may also require smooth surface morphology, low plasma-induced damage, and selective etching of one layer over another. The principal criteria for any plasma etch process is its utility in the fabrication of a device. In this study, we will report plasma etch results for the group-III nitrides and their application to device structures.

  20. Investigation of nanopore evolution in ion track-etched polycarbonate membranes

    NASA Astrophysics Data System (ADS)

    Cornelius, T. W.; Apel, P. Yu.; Schiedt, B.; Trautmann, C.; Toimil-Molares, M. E.; Karim, S.; Neumann, R.

    2007-12-01

    Single heavy ion tracks in polycarbonate foils were chemically etched in an electrolytical cell under various conditions (different temperatures, etchant concentrations, and applied potentials), and the pore evolution was monitored by measuring the current through the membrane. Different zones of the latent tracks could be identified via changes in the radial etching rate with time. Further it was found that the shape of the radial etching rate versus time curves depends on temperature, etchant concentration, and applied voltage. The functionalities are attributed to etching products (double-charged diphenylol-propane anions), which are adsorbed on the pore walls and, thus, affect the further etching process.

  1. Ion beam sputtering of fluoropolymers. [etching polymer films and target surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1978-01-01

    Ion beam sputter processing rates as well as pertinent characteristics of etched targets and films are described. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Sputter target and film characteristics documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs are included.

  2. High Speed Si Etching with ClF3 Cluster Injection

    NASA Astrophysics Data System (ADS)

    Seki, T.; Yoshino, Y.; Senoo, T.; Koike, K.; Ninomiya, S.; Aoki, T.; Matsuo, J.

    2011-01-01

    The reactive gas cluster injection process is an etching method that uses a neutral cluster beam without plasma. ClF3-Ar neutral cluster was generated and the Si etching characteristics with this beam were investigated. ClF3 is very high reactive gas. Adiabatic expansion of a high-pressure gas through a conical nozzle is utilized for the formation of cluster beams. The source gas was a mixture of ClF3 (6%) with Ar (94%). The etching rate increased with source gas pressure nonlinearly, and the etching rate achieved more than 30 μm/min at 0.85 MPa. Although the irradiation energy was very low (<1 eV/atom or molecule), the chemical etching was enhanced with cluster impacts and the cluster bombarded area on the surface was etched selectively. These results indicated that high speed anisotropic etching with low damage can be realized with the ClF3 cluster injection process.

  3. Metal-oxide-semiconductor characterization of silicon surfaces thermally oxidized after reactive ion etching and magnetically enhanced reactive ion etching

    SciTech Connect

    Settlemyer, K.T. Jr.; Ruzyllo, J.; Hwang, D.K.

    1993-03-01

    In this study the performance of reactive ion etching (RIE) and magnetically enhanced reactive ion etching (MERIE) processes in pregate oxidation etching of the field oxide are compared. The comparison is carried out through metal-oxide-semiconductor (MOS) characterization of oxides and interfaces formed on etched silicon surfaces. The results revealed differences in the outcome of RIE and MERIE processes with the latter displaying overall superior characteristics. MERIE induced surface damage is shallower, and is mostly removed during oxide growth. RIE damage propagates deeper into the Si bulk and still influences the MOS devices even after the top Si layers are converted into the oxide. The results obtained emphasize the importance of adequate cleaning of silicon surfaces following RIE/MERIE processes. 5 refs., 4 figs.

  4. Highly chemical reactive ion etching of gallium nitride

    SciTech Connect

    Karouta, F.; Jacobs, B.; Moerman, I.; Jacobs, K.; Weyher, J.L.; Porowski, S.; Crane, R.; Hageman, P.R.

    2000-07-01

    A highly chemical reactive ion etching process has been developed for MOVPE-grown GaN on sapphire. The key element for the enhancement of the chemical property during etching is the use of a fluorine containing gas in a chlorine based chemistry. In the perspective of using GaN substrates for homo-epitaxy of high quality GaN/AlGaN structures they have used the above described RIE process to smoothen Ga-polar GaN substrates. The RMS value, measured by AFM, went from 20 {angstrom} (after mechanical polishing) down to 4 {angstrom} after 6 minutes of RIE. Etching N-polar GaN resulted in a higher etch rate than Ga-polar materials (165 vs. 110 nm/min) but the resulting surface was quite rough and suffers from instability problems. Heat treatment and HCl dip showed a partial recovery of Schottky characteristics after RIE.

  5. Novel spin-on organic hardmask with high plasma etch resistance

    NASA Astrophysics Data System (ADS)

    Oh, Chang-Il; Lee, Jin-Kuk; Kim, Min-Soo; Yoon, Kyong-Ho; Cheon, Hwan-Sung; Tokareva, Nataliya; Song, Jee-Yun; Kim, Jong-Seob; Chang, Tu-Won

    2008-03-01

    In recent years for memory devices under 70nm using ArF lithography, spin-on organic hardmask has become an attractive alternative process to amorphous carbon layer hardmark (ACL) in mass production due to ACL hardmask's limited capacity, high cost-of-ownership, and low process efficiency in spite of its excellent etch performance. However, insufficient plasma etch resistance of spin-on hardmask makes the etch process an issue resulting in inadequate vertical profiles, large CD bias, and narrow etch process window compared to ACL hardmask. In order to be able to apply these spin on hardmasks to varies layers including critical layers, the aforementioned problems need to be resolved and verified using several evaluation methods including etch pattern evaluation. In this paper, we report the synthesis of novel organic spin-on hardmasks (C-SOH) that incorporate various fused aromatic moieties into polymer chain and the evaluation of etch performance using dry etch tools. Organic spin-on hardmasks with 79-90 wt% carbon contents were synthesized in-house. Oxygen and fluorine based plasma etch processes were used to evaluate the etch resistance of the C-SOH. The results show our 3rd generation C-SOH has etch profiles comparable to that of ACL in a 1:1 dense pattern.

  6. Negative ion injection to a wafer in a pulsed two frequency CCP in CF_4/Ar for SiO2 etching*

    NASA Astrophysics Data System (ADS)

    Maeshige, K.; Yagisawa, T.; Makabe, T.

    2001-10-01

    A capacitively coupled plasma (CCP) with electrodes connected respectively to the rf sources for sustaining the plasma at VHF and for biasing the wafer at LF is a powerful tool for a high energy ion assisted SiO2 etching. A time modulation of the two frequency (2f-)CCP by a pulsed-power operation will be one of the practical solutions of the next generation of etcher with the active function of a charging free plasma process for a high aspect ratio hole or trench manufacturing. We have numerically predicted the structure and functions of a pulsed two frequency CCP in CF_4(5%)/Ar, under a consideration of the negative ion production from CF3 in a high density plasma with 10^11cm-3. The functional separation is investigated between a plasma production by VHF (100MHz) and a bias voltage application by LF (1MHz). Alternate injections of high energy positive and negative ions to a patterned wafer are predicted during the off-phase of the pulsed 2f-CCP. It will enable us to provide a function of a local charge neutralization in the bottom of a high aspect ratio hole/trench. [2mm] ^*Work supported by STARC and Selete.

  7. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    SciTech Connect

    Wang, Yufeng; Zeng, Yongbin Qu, Ningsong; Zhu, Di

    2015-07-15

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained.

  8. Controlled in situ etch-back

    NASA Technical Reports Server (NTRS)

    Mattauch, R. J.; Seabaugh, A. C. (Inventor)

    1981-01-01

    A controlled in situ etch-back technique is disclosed in which an etch melt and a growth melt are first saturated by a source-seed crystal and thereafter etch-back of a substrate takes place by the slightly undersaturated etch melt, followed by LPE growth of a layer by the growth melt, which is slightly supersaturated.

  9. Release of multi-layer metal structure in MEMS devices by dry etching technique

    NASA Astrophysics Data System (ADS)

    Das, N. C.

    2002-04-01

    Reactive ion etching technique was used to remove interleave photoresist layer for free standing metal structure in microelectromechanical systems (MEMS) devices. Mixture of oxygen and CF 4 gas was used to get isotropic etching profile. Etching process was optimized to get large metal structure of 100×100 μm 2 without any surface bending. The etching rate of 0.7 μm/min at 60 W of RIE plasma power is found to be optimum process for the particular application. The reported dry release technique is fully compatible with standard silicon IC processing and hence can be used for hybridize process used in MEMS array application.

  10. Vapor etching of nuclear tracks in dielectric materials

    DOEpatents

    Musket, Ronald G.; Porter, John D.; Yoshiyama, James M.; Contolini, Robert J.

    2000-01-01

    A process involving vapor etching of nuclear tracks in dielectric materials for creating high aspect ratio (i.e., length much greater than diameter), isolated cylindrical holes in dielectric materials that have been exposed to high-energy atomic particles. The process includes cleaning the surface of the tracked material and exposing the cleaned surface to a vapor of a suitable etchant. Independent control of the temperatures of the vapor and the tracked materials provide the means to vary separately the etch rates for the latent track region and the non-tracked material. As a rule, the tracked regions etch at a greater rate than the non-tracked regions. In addition, the vapor-etched holes can be enlarged and smoothed by subsequent dipping in a liquid etchant. The 20-1000 nm diameter holes resulting from the vapor etching process can be useful as molds for electroplating nanometer-sized filaments, etching gate cavities for deposition of nano-cones, developing high-aspect ratio holes in trackable resists, and as filters for a variety of molecular-sized particles in virtually any liquid or gas by selecting the dielectric material that is compatible with the liquid or gas of interest.

  11. Etching of photoresist with an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    West, Andrew; van der Schans, Marc; Xu, Cigang; Gans, Timo; Cooke, Mike; Wagenaars, Erik

    2014-10-01

    Low-pressure oxygen plasmas are commonly used in semiconductor industry for removing photoresist from the surface of processed wafers; a process known as plasma ashing or plasma stripping. The possible use of atmospheric-pressure plasmas instead of low-pressure ones for plasma ashing is attractive from the point of view of reduction in equipment costs and processing time. We present investigations of photoresist etching with an atmospheric-pressure plasma jet (APPJ) in helium gas with oxygen admixtures driven by radio-frequency power. In these experiments, the neutral, radical rich effluent of the APPJ is used for etching, avoiding direct contact between the active plasma and the sensitive wafer, while maintaining a high etch rate. Photoresist etch rates and etch quality are measured for a range of plasma operating parameters such as power input, driving frequency, flow rate and wafer temperature. Etch rates of up to 10 micron/min were achieved with modest input power (45 W) and gas flow rate (10 slm). Fourier Transform Infrared (FTIR) spectroscopy showed that the quality of the photoresist removal was comparable to traditional plasma ashing techniques. This work was supported by the UK Engineering and Physical Sciences Research Council Grant EP/K018388/1.

  12. ChISELS 1.0: theory and user manual :a theoretical modeler of deposition and etch processes in microsystems fabrication.

    SciTech Connect

    Plimpton, Steven James; Schmidt, Rodney Cannon; Ho, Pauline; Musson, Lawrence Cale

    2006-09-01

    Chemically Induced Surface Evolution with Level-Sets--ChISELS--is a parallel code for modeling 2D and 3D material depositions and etches at feature scales on patterned wafers at low pressures. Designed for efficient use on a variety of computer architectures ranging from single-processor workstations to advanced massively parallel computers running MPI, ChISELS is a platform on which to build and improve upon previous feature-scale modeling tools while taking advantage of the most recent advances in load balancing and scalable solution algorithms. Evolving interfaces are represented using the level-set method and the evolution equations time integrated using a Semi-Lagrangian approach [1]. The computational meshes used are quad-trees (2D) and oct-trees (3D), constructed such that grid refinement is localized to regions near the surface interfaces. As the interface evolves, the mesh is dynamically reconstructed as needed for the grid to remain fine only around the interface. For parallel computation, a domain decomposition scheme with dynamic load balancing is used to distribute the computational work across processors. A ballistic transport model is employed to solve for the fluxes incident on each of the surface elements. Surface chemistry is computed by either coupling to the CHEMKIN software [2] or by providing user defined subroutines. This report describes the theoretical underpinnings, methods, and practical use instruction of the ChISELS 1.0 computer code.

  13. Temperature-Dependent Nanofabrication on Silicon by Friction-Induced Selective Etching

    NASA Astrophysics Data System (ADS)

    Jin, Chenning; Yu, Bingjun; Xiao, Chen; Chen, Lei; Qian, Linmao

    2016-04-01

    Friction-induced selective etching provides a convenient and practical way for fabricating protrusive nanostructures. A further understanding of this method is very important for establishing a controllable nanofabrication process. In this study, the effect of etching temperature on the formation of protrusive hillocks and surface properties of the etched silicon surface was investigated. It is found that the height of the hillock produced by selective etching increases with the etching temperature before the collapse of the hillock. The temperature-dependent selective etching rate can be fitted well by the Arrhenius equation. The etching at higher temperature can cause rougher silicon surface with a little lower elastic modulus and hardness. The contact angle of the etched silicon surface decreases with the etching temperature. It is also noted that no obvious contamination can be detected on silicon surface after etching at different temperatures. As a result, the optimized condition for the selective etching was addressed. The present study provides a new insight into the control and application of friction-induced selective nanofabrication.

  14. Temperature-Dependent Nanofabrication on Silicon by Friction-Induced Selective Etching.

    PubMed

    Jin, Chenning; Yu, Bingjun; Xiao, Chen; Chen, Lei; Qian, Linmao

    2016-12-01

    Friction-induced selective etching provides a convenient and practical way for fabricating protrusive nanostructures. A further understanding of this method is very important for establishing a controllable nanofabrication process. In this study, the effect of etching temperature on the formation of protrusive hillocks and surface properties of the etched silicon surface was investigated. It is found that the height of the hillock produced by selective etching increases with the etching temperature before the collapse of the hillock. The temperature-dependent selective etching rate can be fitted well by the Arrhenius equation. The etching at higher temperature can cause rougher silicon surface with a little lower elastic modulus and hardness. The contact angle of the etched silicon surface decreases with the etching temperature. It is also noted that no obvious contamination can be detected on silicon surface after etching at different temperatures. As a result, the optimized condition for the selective etching was addressed. The present study provides a new insight into the control and application of friction-induced selective nanofabrication. PMID:27119157

  15. Dry Ice Etches Terrain

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Every year seasonal carbon dioxide ice, known to us as 'dry ice,' covers the poles of Mars. In the south polar region this ice is translucent, allowing sunlight to pass through and warm the surface below. The ice then sublimes (evaporates) from the bottom of the ice layer, and carves channels in the surface.

    The channels take on many forms. In the subimage shown here (figure 1) the gas from the dry ice has etched wide shallow channels. This region is relatively flat, which may be the reason these channels have a different morphology than the 'spiders' seen in more hummocky terrain.

    Observation Geometry Image PSP_003364_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Apr-2007. The complete image is centered at -85.4 degrees latitude, 104.0 degrees East longitude. The range to the target site was 251.5 km (157.2 miles). At this distance the image scale is 25.2 cm/pixel (with 1 x 1 binning) so objects 75 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 06:57 PM and the scene is illuminated from the west with a solar incidence angle of 75 degrees, thus the sun was about 15 degrees above the horizon. At a solar longitude of 219.6 degrees, the season on Mars is Northern Autumn.

  16. Analysis of machining characteristics in electrochemical etching using laser masking

    NASA Astrophysics Data System (ADS)

    Shin, Hong Shik; Chung, Do Kwan; Park, Min Soo; Chu, Chong Nam

    2011-12-01

    Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.

  17. Development of cylindrical reactive ion etching technology for fabricating tubular microstructures

    NASA Astrophysics Data System (ADS)

    Matsui, Tomoki; Takeuchi, Yugo; Shirao, Akitoshi; Nakashima, Yuta; Sato, Katsuya; Minami, Kazuyuki

    2014-05-01

    This paper describes the development of a novel technology that can form a dense and complex pattern on a polymer tube without thermal damage. We have developed an etching mask and equipment capable of processing the tubular material. We named this technology cylindrical RIE (reactive ion etching). In order to evaluate the fundamental processing characteristics of this technology, etching rate, side etching ratio and etching uniformities along the tube axis and circumferential directions are evaluated. As a result, a vertical wall caused by anisotropic etching could be observed, and the average etching rate was 1.0 µm min-1 and the average side etching ratio was 0.027. The maximum differences between etching rate along the axis and circumferential directions were 0.25 and 0.12 µm min-1, respectively. The cross-section of the etched through-groove (slit) processed in a PP (polypropylene) tube having wall thickness of 200 µm was evaluated. By the bowing phenomenon, pattern width decreased most at the middle of the thickness of the tube wall, and average width errors at the middle of the thickness was 22.4 µm. To demonstrate the usefulness of the cylindrical RIE, a stent made of PP tube was fabricated. It was possible to fabricate a stent with an outer diameter of 4.4 mm, length of 19 mm, main strut width of 300 µm, and connecting strut width of 80 µm.

  18. Hydrogen Bubbles and Formation of Nanoporous Silicon during Electrochemical Etching

    SciTech Connect

    Saraf, Laxmikant V.; Baer, Donald R.; Wang, Zheming; Young, James S.; Engelhard, Mark H.; Thevuthasan, Suntharampillai

    2005-06-01

    Many nanoporous Si structures, including those formed by common electrochemical etching procedures, produce a uniformly etch nanoporous surface. If the electrochemical etch rate is slowed down, details of the etch process can be explored and process parameters may be varied to test hypotheses and obtain controlled nanoporous and defect structures. For example, after electrochemical etching of a heavily n-doped (R = 0.05-0.5 ? -cm) <100> silicon at a current density of 10 mA/cm? in buffer oxide etch (BOE) electrolyte solution defect craters, containing textured nanopores, were observed to occur in ring shaped patterns of rings. The defect craters apparently originate at the hydrogen-BOE bubble interface, which forms during hydrogen evolution in the reaction. The slower hydrogen evolution due to low current density allows sufficient bubble residence time so that a high defect density appears at the bubble edges where local reaction rates are highest. Current carrying Si-OH species are most likely responsible for the widening in the craters. Reducing the defect/doping density in silicon lowers the defect concentration and thereby the density of nanopores. Measurements of photoluminescence lifetime and intensity show a distinct feature when the low density of nanopores formed at ring edges are isolated from each other. Overall features observed in photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) intensity strongly emphasize the role of surface oxide that influences these properties.

  19. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Paetzelt, H.; Böhm, G.; Arnold, Th

    2015-04-01

    Local plasma-assisted etching of crystalline silicon by fine focused plasma jets provides a method for high accuracy computer controlled surface waviness and figure error correction as well as free form processing and manufacturing. We investigate a radio-frequency powered atmospheric pressure He/N2/CF4 plasma jet for the local chemical etching of silicon using fluorine as reactive plasma gas component. This plasma jet tool has a typical tool function width of about 0.5 to 1.8 mm and a material removal rate up to 0.068 mm3 min-1. The relationship between etching rate and plasma jet parameters is discussed in detail regarding gas composition, working distance, scan velocity and RF power. Surface roughness after etching was characterized using atomic force microscopy and white light interferometry. A strong smoothing effect was observed for etching rough silicon surfaces like wet chemically-etched silicon wafer backsides. Using the dwell-time algorithm for a deterministic surface machining by superposition of the local removal function of the plasma tool we show a fast and efficient way for manufacturing complex silicon structures. In this article we present two examples of surface processing using small local plasma jets.

  20. Advantages of p++ polysilicon etch stop layer versus p++ silicon

    NASA Astrophysics Data System (ADS)

    Charavel, Remy; Laconte, Jean; Raskin, Jean Pierre

    2003-04-01

    Boron highly doped silicon is now widely used as etch stop layer in MicroElectroMechanical Systems (MEMS) devices fabrication. The present paper shows the advantages of replacing the p++ Si etch stop layer by a p++ polysilicon layer. The etch rate of Tetramethylammoniunhydroxide (TMAH) is measured for LPCVD polysilicon and silicon doped with Boron at concentrations from 8.1018 up to 4.1020 atoms/cm3 which is the Boron solubility limit into Si. TMAH etch being often used during back-end process, selectivity to aluminium is usually needed. The etch selectivity of various TMAH solutions for p++ Si, p++ Poly and aluminium have been measured, from 25 % to 5 % TMAH pure and mixed with silicon powder and ammonium persulfate. Contrarily to silicon, polysilicon is etched isotropically in TMAH solution which constitutes a great advantage when cavities with vertical walls have to be opened. Although the polysilicon etch rate is higher than the silicon one, the selectivity (doped/undoped) is the same for the both materials, allowing identical uses. Another great advantage of polysilicon is that it can be deposited at any process step and does not require clever epitaxy steps or wafer bonding as for silicon. The surface roughness of the etched Poly region is considerably decreased with TMAH mixed with silicon powder and ammonium persulfate mixture compared to pure 25 % TMAH solution. The definition of buried masks in polysilicon layer through Boron implant is the main foreseen application. The p++ Poly buried mask brings solutions for the fabrication of self-aligned double gate MOS, microfluidic or optical networks in MEMS field.

  1. Effect of chemical etching and aging in boiling water on the corrosion resistance of Nitinol wires with black oxide resulting from manufacturing process.

    PubMed

    Shabalovskaya, S; Rondelli, G; Anderegg, J; Simpson, B; Budko, S

    2003-07-15

    The effect of chemical etching in a HF/HNO(3) acid solution and aging in boiling water on the corrosion resistance of Nitinol wires with black oxide has been evaluated with the use of potentiodynamic, modified potentiostatic ASTM F746, and scratch tests. Scanning-electron microscopy, elemental XPS, and Auger analysis were employed to characterize surface alterations induced by surface treatment and corrosion testing. The effect of aging in boiling water on the temperatures of martensitic transformations and shape recovery was evaluated by means of measuring the wire electroresistance. After corrosion tests, as-received wires revealed uniformly cracked surfaces reminiscent of the stress-corrosion-cracking phenomenon. These wires exhibited negative breakdown potentials in potentiostatic tests and variable breakdown potentials in potentiodynamic tests (- 100 mV to + 400 mV versus SCE). Wires with treated surfaces did not reveal cracking or other traces of corrosion attacks in potentiodynamic tests up to + 900-1400-mV potentials and no pitting after stimulation at + 800 mV in potentiostatic tests. They exhibited corrosion behavior satisfactory for medical applications. Significant improvement of corrosion parameters was observed on the reverse scans in potentiodynamic tests after exposure of treated wires to potentials > 1000 mV. In scratch tests, the prepared surfaces repassivated only at low potentials, comparable to that of stainless steel. Tremendous improvement of the corrosion behavior of treated Nitinol wires is associated with the removal of defect surface material and the growth of stable TiO(2) oxide. The role of precipitates in the corrosion resistance of Nitinol-scratch repassivation capacity in particular-is emphasized in the discussion.

  2. Chlorine-based inductively coupled plasma etching of GaAs wafer using tripodal paraffinic triptycene as an etching resist mask

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Ishiwari, Fumitaka; Shoji, Yoshiaki; Kajitani, Takashi; Uehara, Takuya; Nakagawa, Masaru; Fukushima, Takanori

    2016-06-01

    We report the etching properties of tripodal paraffinic triptycene (TripC12) used as a thermal nanoimprint lithography (TNIL) resist mask in Cl2 plasma etching. Using thermally nanoimprinted TripC12 films, we achieved microfabrication of a GaAs substrate by Cl2-based inductively coupled plasma (ICP) etching. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy confirmed that the chemical structure of TripC12 remains intact after the ICP etching process using Cl2. We believe that TNIL using TripC12 films is useful for fabricating optical/electrical devices and micro-electro-mechanical systems (MEMSs).

  3. ZERODUR: bending strength data for etched surfaces

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Leys, Antoine; Carré, Antoine; Kerz, Franca; Westerhoff, Thomas

    2014-07-01

    In a continuous effort since 2007 a considerable amount of new data and information has been gathered on the bending strength of the extremely low thermal expansion glass ceramic ZERODUR®. By fitting a three parameter Weibull distribution to the data it could be shown that for homogenously ground surfaces minimum breakage stresses exist lying much higher than the previously applied design limits. In order to achieve even higher allowable stress values diamond grain ground surfaces have been acid etched, a procedure widely accepted as strength increasing measure. If surfaces are etched taking off layers with thickness which are comparable to the maximum micro crack depth of the preceding grinding process they also show statistical distributions compatible with a three parameter Weibull distribution. SCHOTT has performed additional measurement series with etch solutions with variable composition testing the applicability of this distribution and the possibility to achieve further increase of the minimum breakage stress. For long term loading applications strength change with time and environmental media are important. The parameter needed for prediction calculations which is combining these influences is the stress corrosion constant. Results from the past differ significantly from each other. On the basis of new investigations better information will be provided for choosing the best value for the given application conditions.

  4. Pattern inspection of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2015-10-01

    Patterned mask inspection for an etched multilayer (ML) EUV mask was investigated. In order to optimize the mask structure from the standpoint of not only a pattern inspection by using a projection electron microscope (PEM), but also by considering the other fabrication processes using electron beam (EB) techniques such as CD metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients (SEECs) of the candidate materials for conductive layer, we evaluated the image contrast and the influence of charging effect. In the cases of 40-pair-ML, 16 nm sized extrusion and intrusion defects were found to be detectable more than 10 sigma in hp 44 nm, 40 nm, and 32 nm line and space (L/S) patterns. Reducing 40-pair-ML to 20-pair-ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16 nm sized defects remained detectable. These defects were also detected after the etched part was refilled with Si. Moreover, the simulation shows a high sensitivity for detecting the residual-type defects (etching residues). A double layer structure with 2.5-nm-thik B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  5. Seeking Methods to Reduce the Aspect Ratio Dependence in Deep Silicon Etch

    NASA Astrophysics Data System (ADS)

    Bates, Robert L.; Goeckner, M. J.; Overzet, L. J.

    2012-10-01

    We are examining how to reduce the Aspect Ratio Dependence (ARD) of deep silicon etch processes while maintaining both smooth sidewalls and an acceptable etch rate. In particular, SF6/O2/Ar and SF6/C4F8/Ar plasmas have both been shown to etch silicon with good anisotropy in a continuous etch process producing good sidewall profiles and at acceptable etch rates. Unfortunately, these processes also suffer from significant ARD. We are proposing to use an ARD deposition process to balance the ARD of the etch process and thereby find a reasonably AR independent process having an acceptable overall etch rate. To do this, we propose to examine both the ARD deposition rate into various AR trenches and the ARD etch rate of the passivation layer in those trenches. We are pursuing this in part because other researchers have shown that the etch rate of low AR features can be reduced (by depositing a passivation layer) and allow larger AR features to ``catch up.'' As a result, the same depth trench can be obtained [1]. The work is being carried out in a Plasma-Therm Versaline reactor in the UTD clean room. [4pt] [1] See for example: S. Lai, D. Johnson & R. Westerman, J.Vac. Sci. Tech. A, 24, 1283, (2006).

  6. Formation of plasma induced surface damage in silica glass etching for optical waveguides

    NASA Astrophysics Data System (ADS)

    Choi, D. Y.; Lee, J. H.; Kim, D. S.; Jung, S. T.

    2004-06-01

    Ge, B, P-doped silica glass films are widely used as optical waveguides because of their low losses and inherent compatibility with silica optical fibers. These films were etched by ICP (inductively coupled plasma) with chrome etch masks, which were patterned by reactive ion etching (RIE) using chlorine-based gases. In some cases, the etched surfaces of silica glass were very rough (root-mean square roughness greater than 100 nm) and we call this phenomenon plasma induced surface damage (PISD). Rough surface cannot be used as a platform for hybrid integration because of difficulty in alignment and bonding of active devices. PISD reduces the etch rate of glass and it is very difficult to remove residues on a rough surface. The objective of this study is to elucidate the mechanism of PISD formation. To achieve this goal, PISD formation during different etching conditions of chrome etch mask and silica glass was investigated. In most cases, PISD sources are formed on a glass surface after chrome etching, and metal compounds are identified in theses sources. Water rinse after chrome etching reduces the PISD, due to the water solubility of metal chlorides. PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching. In conclusion, PISD sources come from the chrome etching process, and polymer deposition on these sources during the silica etching cause the PISD sources to grow. In the area close to the PISD source there is a higher ion flux, which causes an increase in the etch rate, and results in the formation of a pit.

  7. Parallel preparation of plan-view transmission electron microscopy specimens by vapor-phase etching with integrated etch stops.

    PubMed

    English, Timothy S; Provine, J; Marshall, Ann F; Koh, Ai Leen; Kenny, Thomas W

    2016-07-01

    Specimen preparation remains a practical challenge in transmission electron microscopy and frequently limits the quality of structural and chemical characterization data obtained. Prevailing methods for thinning of specimens to electron transparency are serial in nature, time consuming, and prone to producing artifacts and specimen failure. This work presents an alternative method for the preparation of plan-view specimens using isotropic vapor-phase etching with integrated etch stops. An ultrathin amorphous etch-stop layer simultaneously serves as an electron transparent support membrane whose thickness is defined by a controlled growth process such as atomic layer deposition with sub-nanometer precision. This approach eliminates the need for mechanical polishing or ion milling to achieve electron transparency, and reduces the occurrence of preparation induced artifacts. Furthermore, multiple specimens from a plurality of samples can be thinned in parallel due to high selectivity of the vapor-phase etching process. These features enable dramatic reductions in preparation time and cost without sacrificing specimen quality and provide advantages over wet etching techniques. Finally, we demonstrate a platform for high-throughput transmission electron microscopy of plan-view specimens by combining the parallel preparation capabilities of vapor-phase etching with wafer-scale micro- and nanofabrication.

  8. Plasma etching of polymers like SU8 and BCB

    NASA Astrophysics Data System (ADS)

    Mischke, Helge; Gruetzner, Gabi; Shaw, Mark

    2003-01-01

    Polymers with high viscosity, like SU8 and BCB, play a dominant role in MEMS application. Their behavior in a well defined etching plasma environment in a RIE mode was investigated. The 40.68 MHz driven bottom electrode generates higher etch rates combined with much lower bias voltages by a factor of ten or a higher efficiency of the plasma with lower damaging of the probe material. The goal was to obtain a well-defined process for the removal and structuring of SU8 and BCB using fluorine/oxygen chemistry, defined using variables like electron density and collision rate. The plasma parameters are measured and varied using a production proven technology called SEERS (Self Excited Electron Resonance Spectroscopy). Depending on application and on Polymer several metals are possible (e.g., gold, aluminum). The characteristic of SU8 and BCB was examined in the case of patterning by dry etching in a CF4/O2 chemistry. Etch profile and etch rate correlate surprisingly well with plasma parameters like electron density and electron collision rate, thus allowing to define to adjust etch structure in situ with the help of plasma parameters.

  9. Controlled Layer-by-Layer Etching of MoS₂.

    PubMed

    Lin, TaiZhe; Kang, BaoTao; Jeon, MinHwan; Huffman, Craig; Jeon, JeaHoo; Lee, SungJoo; Han, Wei; Lee, JinYong; Lee, SeHan; Yeom, GeunYoung; Kim, KyongNam

    2015-07-29

    Two-dimensional (2D) metal dichalcogenides like molybdenum disulfide (MoS2) may provide a pathway to high-mobility channel materials that are needed for beyond-complementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS2 devices. In this study, we propose a layer-by-layer removal of MoS2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar)(+) ion-beam desorption. MoS2 etching was not observed with only the Cl-radical adsorption or low-energy (<20 eV) Ar(+) ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar(+) ion-beam desorption step resulted in the complete etching of one monolayer of MoS2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer of MoS2 with each ALET cycle; therefore, the number of MoS2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS2.

  10. Integration of Nanotubes, Etch Tracks, and Nanoribbons in Crystallographic Alignment

    NASA Astrophysics Data System (ADS)

    Boland, Mathias J.; Hunley, D. Patrick; Sundrarajan, Abhishek; Nasseri, Mohsen; Strachan, Douglas R.

    2015-03-01

    Three nanomaterial components, carbon nanotubes (CNTs), few-layer graphene (FLG), and etch tracks exposing insulating SiO2 regions, are integrated to form crystallographically-aligned nanoscale systems. These integrated systems consist of CNTs grown across nanogap etch tracks and nanoribbons formed within the FLG films as a result of chemical vapor deposition (CVD) processing. Each nanoscale component is aligned along the underlying graphene lattice, resulting in their orientations being locked into precise values, with CNTs maintaining alignment even after crossing etch tracks. The growth of aligned CNTs across nanogap etch tracks and nanoribbons suggests that integrated formations can be achieved by growing CNTs directly over nanogap etch tracks and nanoribbons. This is supported by calculations of the vibrational energy of CNTs indicating that they should be capable of maintaining atomic registry with an underlying graphene lattice as they grow across a typical etch track, in agreement with our experimental results. Thus, this work is relevant to the integration of semiconducting, conducting, and insulating nano-materials all together into precise nano-electronic systems.

  11. High rate dry etching of (BiSb)2Te3 film by CH4/H2-based plasma

    NASA Astrophysics Data System (ADS)

    Song, Junqiang; Shi, Xun; Chen, Lidong

    2014-10-01

    Etching characteristics of p-type (BiSb)2Te3 films were studied with CH4/H2/Ar gas mixture using an inductively coupled plasma (ICP)-reactive ion etching (RIE) system. The effects of gas mixing ratio, working pressure and gas flow rate on the etch rate and the surface morphology were investigated. The vertical etched profile with the etch rate of 600 nm/min was achieved at the optimized processing parameters. X-ray photoelectron spectroscopy (XPS) analysis revealed the non-uniform etching of (BiSb)2Te3 films due to disparate volatility of the etching products. Micro-masking effects caused by polymer deposition and Bi-rich residues resulted in roughly etched surfaces. Smooth surfaces can be obtained by optimizing the CH4/H2/Ar mixing ratio.

  12. Method of plasma etching Ga-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2012-12-25

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

  13. Smooth and Vertical Profile Dry Etching of Si Using XeF2 Plasma

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Ohtsuki, Hideo; Koyama, Fumio

    2009-06-01

    We demonstrated the discharge of XeF2 plasma and investigated the dry etching process of Si using XeF2 plasma. A vertical etching profile and a smooth etched surface, which satisfy the requirements for optical device fabrication, were obtained. The etching rate of Si was 0.7 µm/min at 1 Pa and 100 W. It was found that the RF power dependences of the emission intensities of Xe, F, and XeF were similar to that of the etching rate of Si. The etching rate ratio of Si to SiO2 in the XeF2 plasma etching process was approximately 10, which was much larger than that in the CF4/O2 plasma etching process. We believe that XeF2 plasma etching is a very simple and useful process for Si-based optical devices such as photonic crystals, narrow optical waveguides, and micro-electro-mechanical systems (MEMS) device fabrication.

  14. Development and Research on the Mechanism of Novel Mist Etching Method for Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Kawaharamura, Toshiyuki; Hirao, Takashi

    2012-03-01

    A novel etching process with etchant mist was developed and applied to oxide thin films such as zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), and indium tin oxide (ITO). By using this process, it was shown that precise control of the etching characteristics is possible with a reasonable etching rate, for example, in the range of 10-100 nm/min, and a fine pattern of high accuracy can also be realized, even though this is usually very difficult by conventional wet etching processes, for ZnO and ZnMgO. The mist etching process was found to be similarly and successfully applied to ITO. The mechanism of mist etching has been studied by examining the etching temperature dependence of pattern accuracy, and it was shown that the mechanism was different from that of conventional liquid-phase spray etching. It was ascertained that fine pattern etching was attained using mist droplets completely (or partly) gasified by the heat applied to the substrate. This technique was applied to the fabrication of a ZnO thin-film transistor (TFT) with a ZnO active channel length of 4 µm. The electrical properties of the TFT were found to be excellent with fine uniformity over the entire 4-in. wafer.

  15. Rate controlled metal assisted chemical etching to fabricate vertical and uniform Si nanowires

    NASA Astrophysics Data System (ADS)

    Song, Ari; Yun, Seokhun; Lokhande, Vaibhav; Ji, Taeksoo

    2016-03-01

    Mac(metal assisted chemical) etching is a simple, low-cost and anisotropic etching method to make Si NWs (silicon nanowires). In this method, smaller surface area is damaged compared to dry etching process, either. Mac etching uses a combination of an oxide removal acid (e.g. HF), an oxidant (e.g. H2O2) with a noble metal (e.g. Au, Ag, Pt, etc.) as the catalyst. Typically, the Si beneath the noble metal is etched faster than the Si without noble metal coverage by electron transfer mechanism at the noble metal /solution and the noble metal/Si interface. While Mac etching to build Si NWs, unwanted etching occurs in the bulk silicon layer resulting from excess hole diffusion caused by the increase in hole concentration at the nearby metal layers. In this study, we explored the ratio of oxidant to oxide removal acid in the Mac etching solution that is most effective in etching the Si underneath the noble metal layer suppressing the unwanted etching. At the optimized ratio, Si NWs were fabricated at a faster rate with good uniformity.

  16. Effect of reactive gas (oxygen/chlorine/fluorine) etching on the magnetic flux of a high moment write pole material

    SciTech Connect

    Zhang Jinqiu; Liu Feng; Chen Lifan; Miloslavsky, Lena

    2010-05-15

    Effect of reactive gas (oxygen/chlorine/fluorine) etching on NiFe magnetic properties was investigated. Experimental data showed 40% magnetic property degradation for F-containing gas etching, 10% degradation for O-containing gas etching, and 5% degradation for Cl-containing gas etching processes. X-ray diffraction analysis indicated that the crystallographic orientation remained the same upon the reactive gas etching, which is due to the low ion energy in plasma etching process as opposed to ion milling process with high input energy. It is proposed that the reported magnetic property degradation was mainly caused by the nonmagnetic dead layer formation, rather than the changes in the crystallographic orientation. The dead layer was determined by the NiFe thickness dependence of remnant magnetic flux variations between pre-etched and postetched samples. The dead layer remained nearly constant for O-containing gas etching process with increasing plasma processing time. The nonmagnetic dead layer of {approx}40-50 A formed in O-containing etching gas was observed in transmission electron microscopy cross-sectional image and was in very good agreement with the calculated value based on magnetic flux measurements. Combined magnetic and physical characterizations suggest that the dead layer thickness saturates at the initial stage of the plasma etching and magnetic property remained unchanged with increasing etching duration upon formation of the dead layer.

  17. Wet etching studies of aluminum nitride bulk crystals and their sublimation growth by microwaves

    NASA Astrophysics Data System (ADS)

    Zhuang, Dejin

    The research described in this dissertation was motivated by the need of bulk AlN single crystals to improve the quality of group III nitride based devices. In this dissertation, first the evolution of semiconductors is reviewed. Second, historical reviews and recent advances of AlN crystal growth are presented. Third, the experimental setup and characterization methods are described. Finally, four papers regarding wet etching and sublimation growth of AlN are attached: (1) AlN bulk crystal growth using microwaves as heat source; (2) a review of wet etching of GaN and AlN; (3) anisotropic etching technique for identifying AlN crystal polarities; and (4) defect-selective etching to reveal dislocations in Al-polar crystals. Single crystalline AIN platelets up to 2 x 3 mm2 and needles 3 mm long were successfully grown by directly heating the source materials with microwaves. The grown crystals were characterized by optical microscopy, photoluminescence (PL), Raman spectroscopy, synchrotron white beam X-ray topography (SWBXT), and defect-selective etching. The grown crystals have good structural quality, with etch pit density as low as 103 cm -2. A peak positioned at 5.5 eV in PL spectra was attributed to magnesium impurities, presumably originating from the source materials. The wet etchings of GaN and AlN by electrochemical etching and defect-selective etching are reviewed. The mechanism of each etching process and etching conditions resulting in highly anisotropic, dopant-type/bandgap selective, defect-selective, and smooth surfaces are discussed. The applications of wet etching techniques in device fabrication and crystal characterization are also reviewed. The anisotropic etching technique for AlN crystals was successfully developed. Aqueous KOH solution did not attack Al-polar surfaces, but produced hexagonal hillocks on N-polar surfaces. The etching results suggested that freely nucleated AlN crystals predominately have the Al polarity facing the source

  18. Plasma Etching Improves Solar Cells

    NASA Technical Reports Server (NTRS)

    Bunyan, S. M.

    1982-01-01

    Etching front surfaces of screen-printed silicon photovoltaic cells with sulfur hexafluoride plasma found to increase cell performance while maintaining integrity of screen-printed silver contacts. Replacement of evaporated-metal contacts with screen-printed metal contacts proposed as one way to reduce cost of solar cells for terrestrial applications.

  19. Photoinduced laser etching of a diamond surface

    SciTech Connect

    Kononenko, V V; Komlenok, M S; Pimenov, S M; Konov, V I

    2007-11-30

    Nongraphitising ablation of the surface of a natural diamond single crystal irradiated by nanosecond UV laser pulses is studied experimentally. For laser fluences below the diamond graphitisation threshold, extremely low diamond etching rates (less than 1nm/1000 pulses) are obtained and the term nanoablation is used just for this process. The dependence of the nanoablation rate on the laser fluence is studied for samples irradiated both in air and in oxygen-free atmosphere. The effect of external heating on the nanoablation rate is analysed and a photochemical mechanism is proposed for describing it. (interaction of laser radiation with matter. laser plasma)

  20. Decontamination of metals using chemical etching

    DOEpatents

    Lerch, Ronald E.; Partridge, Jerry A.

    1980-01-01

    The invention relates to chemical etching process for reclaiming contaminated equipment wherein a reduction-oxidation system is included in a solution of nitric acid to contact the metal to be decontaminated and effect reduction of the reduction-oxidation system, and includes disposing a pair of electrodes in the reduced solution to permit passage of an electrical current between said electrodes and effect oxidation of the reduction-oxidation system to thereby regenerate the solution and provide decontaminated equipment that is essentially radioactive contamination-free.

  1. Understanding anisotropic plasma etching of two-dimensional polystyrene opals for advanced materials fabrication.

    PubMed

    Akinoglu, Eser M; Morfa, Anthony J; Giersig, Michael

    2014-10-21

    Anisotropic deformation of polystyrene particles in an oxygenated (O2/Ar) plasma is observed for radio frequency (rf) plasma and inductively coupled plasma (ICP). A facile model based on a ratio of completely isotropic and completely anisotropic etching is presented to describe the anisotropy of the etching process and is implemented to determine the height of the spheroid-shaped polystyrene particles. In our systems, we find the plasma etching to be 54% isotropic in the rf plasma and 79% isotropic in the ICP. With this model, the maximum material deposition thickness for nanofabrication with plasma-etched nanosphere lithography or colloid lithography can be predicted. Moreover, the etching of polystyrene particles in an oxygenated plasma is investigated versus the etching time, gas flow, gas composition, temperature, substrate material, and particle size. The results of this study allow precise shape tuning during the fabrication of nanostructured surfaces with size-dependent properties for bionic, medical, and photonic applications. PMID:24580644

  2. Understanding anisotropic plasma etching of two-dimensional polystyrene opals for advanced materials fabrication.

    PubMed

    Akinoglu, Eser M; Morfa, Anthony J; Giersig, Michael

    2014-10-21

    Anisotropic deformation of polystyrene particles in an oxygenated (O2/Ar) plasma is observed for radio frequency (rf) plasma and inductively coupled plasma (ICP). A facile model based on a ratio of completely isotropic and completely anisotropic etching is presented to describe the anisotropy of the etching process and is implemented to determine the height of the spheroid-shaped polystyrene particles. In our systems, we find the plasma etching to be 54% isotropic in the rf plasma and 79% isotropic in the ICP. With this model, the maximum material deposition thickness for nanofabrication with plasma-etched nanosphere lithography or colloid lithography can be predicted. Moreover, the etching of polystyrene particles in an oxygenated plasma is investigated versus the etching time, gas flow, gas composition, temperature, substrate material, and particle size. The results of this study allow precise shape tuning during the fabrication of nanostructured surfaces with size-dependent properties for bionic, medical, and photonic applications.

  3. A highly selective, chlorofluorocarbon-free GaAs on AlGaAs etch

    SciTech Connect

    Smith, L.E. . Solid State Technology Center)

    1993-07-01

    A highly selective reactive ion etching process using SiCl[sub 4], CF[sub 4], O[sub 2], and He is reported. The selectivity of the etch, which is adjustable, ranges from 308:1 to 428:1 for GaAs to Al[sub 0.11]Ga[sub 0.89]As. This variability in selectivity is achieved by adjusting the helium flow rate. One very attractive feature of this etch is that it uses no chlorofluorocarbons and therefore complies with future bans on these substances imposed at both federal and corporate levels. The etch is demonstrated on a GaAs field effect transistor structure with an underlying Al[sub 0.11]Ga[sub 0.89]As stop-etch layer. The etch can be used for both anisotropic and isotropic applications.

  4. Selective photochemical dry etching of compound semiconductors: Enhanced control through secondary electronic properties

    SciTech Connect

    Ashby, C.I.H.

    1988-01-01

    When laser-driven etching of a semiconductor requires direct participation of photogenerated carriers, the etching quantum yield will be sensitive to the electronic properties of a specific semiconductor material. The band-gap energy of the semiconductor determines the minimum photon energy needed for carrier-driven etching since sub-gap photons do not generate free carriers. However, only those free carriers that reach the reacting surface contribute to etching and the ultimate carrier flux to the surface is controlled by more subtle electronic properties than the lowest-energy band gap. For example, the initial depth of carrier generation and the probability of carrier recombination between the point of generation and the surface profoundly influence the etching quantum yield. Appropriate manipulation of process parameters can provide additional reaction control based on such secondary electronic properties. Applications to selective dry etching of GaAs and related materials are discussed here. 17 refs., 7 figs.

  5. Deep GaN etching by inductively coupled plasma and induced surface defects

    SciTech Connect

    Ladroue, J.; Meritan, A.; Boufnichel, M.; Lefaucheux, P.; Ranson, P.; Dussart, R.

    2010-09-15

    GaN etching was studied in Cl{sub 2}/Ar plasmas as a function of process parameters. In addition, for a better understanding of the etching mechanisms, Langmuir probe measurements and optical emission spectroscopy were carried out. Etch rate was found to depend strongly on bias power. After optimization, an etch rate greater than 1000 nm/min was achieved. A second part of this work is dedicated to the etched surface defects. An original method to estimate GaN dislocation density and to localize nanopipes in the material is presented. Columnar defects could also appear with impurities in the etching reactor. The authors also present a possible formation mechanism of those columnar defects.

  6. CF3Br plasma cryo etching of low-k porous dielectric

    NASA Astrophysics Data System (ADS)

    Clemente, I.; Koehler, N.; Miakonkikh, A.; Zimmermann, S.; Schulz, S. E.; Rudenko, K.

    2016-08-01

    Process of plasma etching of CVD low-k dielectric was studied. We used CF3Br low pressure ICP plasma for etching at cryo temperatures (-20°C — -100°C), pressures (5-20 mTorr) and RF bias with effective DC voltage 80-140 V. Refractive index of film and its thickness were measured by spectral ellipsometry. Ellipsometric porosimetry was employed to compare pore size distribution before and after etching of films. Measurements show increasing of etch rate increase with decreasing sample temperature.

  7. Apparatus for edge etching of semiconductor wafers

    NASA Technical Reports Server (NTRS)

    Casajus, A.

    1986-01-01

    A device for use in the production of semiconductors, characterized by etching in a rapidly rotating etching bath is described. The fast rotation causes the surface of the etching bath to assume the form of a paraboloid of revolution, so that the semiconductor wafer adjusted at a given height above the resting bath surface is only attacked by etchant at the edges.

  8. Nanoscrews: Asymmetrical Etching of Silver Nanowires.

    PubMed

    Tan, Rachel Lee Siew; Chong, Wen Han; Feng, Yuhua; Song, Xiaohui; Tham, Chu Long; Wei, Jun; Lin, Ming; Chen, Hongyu

    2016-08-31

    World's smallest screws with helical threads are synthesized via mild etching of Ag nanowires. With detailed characterization, we show that this nanostructure arises not from the transformation of the initial lattice, but the result of a unique etching mode. Three-dimensional printed models are used to illustrate the evolution of etch pits, from which a possible mechanism is postulated. PMID:27513181

  9. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K. (Inventor); Giapis, Konstantinos P. (Inventor)

    1999-01-01

    An at-least dual chamber apparatus and method in which high flux beams of fast moving neutral reactive species are created, collimated and used to etch semiconductor or metal materials from the surface of a workpiece. Beams including halogen atoms are preferably used to achieve anisotropic etching with good selectivity at satisfactory etch rates. Surface damage and undercutting are minimized.

  10. Modeling aluminum etch chemistry in high density plasmas

    SciTech Connect

    Meeks, E.; Ho, P.; Buss, R.

    1997-08-01

    The authors have assembled a chemical reaction mechanism that describes the BCl{sub 3}/Cl{sub 2}/Ar plasma etch of Al metallization layers. The reaction set for gas-phase and surface processes was derived either from literature data or estimated from data on related systems. A well-mixed reactor model was used to develop the mechanism and test it against experimental measurements of plasma species and etch-rates in processing reactors. Finally, use of reduced chemistry mechanisms are demonstrated in 2-D simulations for a complex reactor geometry.

  11. Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas

    SciTech Connect

    Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M. Economou, Demetre J.

    2014-05-28

    Cl{sub 2}, Br{sub 2}, HBr, Br{sub 2}/Cl{sub 2}, and HBr/Cl{sub 2} feed gases diluted in Ar (50%–50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br{sub 2}/Ar and HBr/Cl{sub 2}/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF{sub 2}, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl{sub 2}/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to 〈110〉 cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

  12. Deep SiO2 etching with Al and AlN masks for MEMS devices

    NASA Astrophysics Data System (ADS)

    Bliznetsov, Vladimir; Mao Lin, Hua; Zhang, Yue Jia; Johnson, David

    2015-08-01

    Silicon oxide-based materials such as quartz and silica are widely used in microelectromechanical systems (MEMS). One way to enhance the capability of their deep plasma etching is to increase selectivity by the use of hard masks. Although this approach was studied previously, information on the use of hard masks for the etching of silicon-oxide based materials on 200 mm substrates is scarce. We present the results of etching process development for amorphous silicon oxide using Al and AlN masks with a view of the application of the results for the etching of silica and quartz. Three gas chemistries (C4F8/O2, CF4 and SF6) and their mixtures were compared in an industrial reactive ion etch (RIE) chamber with two plasma sources. It was established that pure SF6 is the best etchant and AlN is a better mask than Al for providing higher selectivity and a sidewall angle close to vertical. A range of etching parameters for micromasking-free etching was established and etched structures of up to a 4 : 1 aspect ratio were created in 21 μm-thick oxide using the process with an etch rate of 0.32-0.36 μm min-1 and a selectivity to AlN mask of (38-49) : 1.

  13. Modifying of etching anisotropy of silicon substrates by surface active agents

    NASA Astrophysics Data System (ADS)

    Rola, Krzysztof; Zubel, Irena

    2011-04-01

    The influence of alcohol additives on etch rate anisotropy of Si(hkl) planes has been studied. The etching processes were carried out in 3 and 5 M KOH aqueous solutions saturated and non-saturated with alcohols. Isopropanol, 1-propanol and tert-butanol were examined. It has been showed that the etching process cannot be controlled only by the surface tension of the solution. Saturation of the etching solution with alcohols modifies etch rate anisotropy, lowering the ratio of the etch rate of (110) and vicinal planes to the etch rate of (100) plane. The morphology of Si(hkl) planes etched in 3 M KOH solution saturated with tert-butyl alcohol has been studied in detail. Smooth (331) and (221) planes have been achieved in this solution. The (100) plane turned out to be densely covered by hillocks, opposite to the (100) plane etched in weak-alkaline solution saturated with isopropanol. To explain this phenomenon, the mechanism of hillocks formation on Si(100) surface has been proposed.

  14. Modifying of etching anisotropy of silicon substrates by surface active agents

    NASA Astrophysics Data System (ADS)

    Rola, Krzysztof P.; Zubel, Irena

    2011-04-01

    The influence of alcohol additives on etch rate anisotropy of Si( hkl) planes has been studied. The etching processes were carried out in 3 and 5 M KOH aqueous solutions saturated and non-saturated with alcohols. Isopropanol, 1-propanol and tert-butanol were examined. It has been showed that the etching process cannot be controlled only by the surface tension of the solution. Saturation of the etching solution with alcohols modifies etch rate anisotropy, lowering the ratio of the etch rate of (110) and vicinal planes to the etch rate of (100) plane. The morphology of Si( hkl) planes etched in 3 M KOH solution saturated with tert-butyl alcohol has been studied in detail. Smooth (331) and (221) planes have been achieved in this solution. The (100) plane turned out to be densely covered by hillocks, opposite to the (100) plane etched in weak-alkaline solution saturated with isopropanol. To explain this phenomenon, the mechanism of hillocks formation on Si(100) surface has been proposed.

  15. Fabrication of pyramidal corrugated quantum well infrared photodetector focal plane arrays by inductively coupled plasma etching with BCl/Ar

    NASA Astrophysics Data System (ADS)

    Sun, Jason; Choi, Kwong-Kit; Lee, Unchul

    2012-10-01

    We developed an optimized inductively coupled plasma etching process to produce gallium arsenide (GaAs) pyramidal corrugated quantum well infrared photodetector focal plane arrays (C-QWIP FPAs). A statistically designed experiment was performed to optimize the etching parameters. The resulting parameters are discussed in terms of the effect on the etching rate and profile. This process uses a small amount of mask corrosion and the control of the etching mask gap to give a 45 deg to 50 deg V-groove etching profile, which is independent of the crystal orientation of GaAs. In the etching development, scanning electron microscope was used to observe the surface morphology and the pattern profile. In addition, x-ray photoelectron spectroscopy was used to obtain the elemental composition and contamination of the etching surface. It is found that extremely small stoichiometric change and surface damage of the etching surface can be achieved while keeping a relatively high etching rate and ˜45 deg V-groove etching profile. This etching process is applied to the fabrication of pyramidal C-QWIP FPAs successfully, which are expected to have better performance than the regular prism-shaped C-QWIPs according to electromagnetic modeling.

  16. Dissolution kinetics and etch pit studies of potassium aluminium sulphate

    NASA Astrophysics Data System (ADS)

    van der Hoek, B.; Van Enckevort, W. J. P.; Van Der Linden, W. H.

    1983-03-01

    The dissolution process of the {111} faces of potash alum is studied, both by microtopographic examinations of the etch pit patterns and by measurement of the dissolution kinetics in a rotating disc crystallizer. Both methods showed that the Cabrera-Levine dissolution theory holds for the two most common dislocation types ending on the {111} faces of potash alum. On the basis of the rotating disc experiments, the interfacial supersaturation of the etch pit experiments was roughly estimated. Using this, it was found that at interfacial supersaturations below -0.6% (dislocations with <110> Burgers vector) or below -0.85% (dislocations with <100> Burgers vector) numerous etch pits related to those dislocation types appeared. Below those undersaturations the dissolution process is mainly determined by volume diffusion. From the critical undersaturation, determined in the rotating disc crystallizer, the value of the edge free energy of a step was found to be approximately 0.01 J/m 2.

  17. Fabrication of sub-15 nm aluminum wires by controlled etching

    NASA Astrophysics Data System (ADS)

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; McQueen, T. M.; Marković, N.

    2014-04-01

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  18. Dry etching of SiC using Ar/F2 plasma and XeF2 plasma

    NASA Astrophysics Data System (ADS)

    Matsutani, Akihiro; Koyama, Fumio

    2015-06-01

    We investigated the SiC dry etching process using Ar/F2 plasma and XeF2 plasma. We carried out optical observation of Ar/F2 plasma and XeF2 plasma. The dominant etching species were different between Ar/F2 plasma and XeF2 plasma. The etching rates of SiC were approximately 100 nm/min at 25 sccm and 200 W for Ar/F2 plasma and 45 nm/min at 2.5 sccm and 100 W for XeF2 plasma. Vertical etching profiles and a smooth etched surface were obtained. The average roughness of the etched bottom surface was 1 nm, which satisfied the requirements for optical device fabrication. We believe that the proposed etching process using F2 of zero-global-warming-potential gases is very simple and useful for fabricating optical devices and micro-electromechanical systems (MEMSs).

  19. Electron Cyclotron Resonance-Reactive Ion Etching of III-V Semiconductors by Cyclic Injection of CH4/H2/Ar and O2 with Constant Ar Flow

    NASA Astrophysics Data System (ADS)

    Haneji, Nobuo; Segami, Goh; Ide, Tomoyoshi; Suzuki, Tatsuya; Arakawa, Taro; Tada, Kunio; Shimogaki, Yukihiro; Nakano, Yoshiaki

    2003-06-01

    Electron cyclotron resonance-reactive ion etching (ECR-RIE) is very useful for fabricating semiconductor photonic devices and integrated circuits (PICs). The mixture gas of CH4/H2 is used for etching III-V semiconductors, but the carbon polymer film deposited on the surface during the etching process presents some problems. Thus, the polymer film must be ashed off using an O2 plasma. We introduced the cyclic injection of CH4/H2/Ar and O2 to ECR-RIE, and demonstrated that it was very useful for etching of InP. However, compound semiconductors containing Al (e.g., AlGaAs and InAlAs) react with oxygen and an alumina layer is formed, which cannot be etched by CH4/H2 etching. Therefore, we used a new cyclic etching process with constant Ar flow in the chamber to remove this alumina layer by Ar ion etching, and obtained good results for etching rate and surface morphology for the compound semiconductors containing Al. We also proposed a suitable combination of three cyclic etching procedures (continuous etching, cyclic etching without constant Ar flow and cyclic etching with constant Ar flow) for etching the multilayer heterostructure of III-V semiconductors including InP and/or compound semiconductors containing Al.

  20. Effect of Cl{sub 2}/Ar gas mixing ratio on (Pb,Sr)TiO{sub 3} thin film etching behavior in inductively coupled plasma

    SciTech Connect

    Kim, Gwan-Ha; Kim, Chang-Il

    2006-07-15

    The development of anisotropic etching process for (Pb,Sr)TiO{sub 3} (PST) thin films is an important task to provide a small feature size and an accurate pattern transfer. Etching characteristics of PST thin films were investigated using inductively coupled plasma etching system as functions of Cl{sub 2}/Ar gas mixing ratio. The PST etch rate increased with the increase of chlorine radical and ion energy intensity. It was found that the increasing of Ar content in gas mixture lead to sufficient increasing of etch rate. The maximum etch rate of PST film is 56.2 nm/min at Cl{sub 2}/(Cl{sub 2}+Ar) of 0.2. It was proposed that the sputter etching is a dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

  1. A Reactive-Ion Etch for Patterning Piezoelectric Thin Film

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok; Wild, Larry

    2003-01-01

    Reactive-ion etching (RIE) under conditions described below has been found to be a suitable means for patterning piezoelectric thin films made from such materials as PbZr(1-x)Ti(x)O3 or Ba(x)Sr(1.x)TiO3. In the original application for which this particular RIE process was developed, PbZr(1-x)Ti(x)O3 films 0.5 microns thick are to be sandwiched between Pt electrode layers 0.1 microns thick and Ir electrode layers 0.1 microns thick to form piezoelectric capacitor structures. Such structures are typical of piezoelectric actuators in advanced microelectromechanical systems now under development or planned to be developed in the near future. RIE of PbZr(1-x)Ti(x)O3 is usually considered to involve two major subprocesses: an ion-assisted- etching reaction, and a sputtering subprocess that removes reactive byproducts. RIE is favored over other etching techniques because it offers a potential for a high degree of anisotropy, high-resolution pattern definition, and good process control. However, conventional RIE is not ideal for patterning PbZr(1-x)Ti(x)O3 films at a thickness as great as that in the original intended application. In order to realize the potential benefits mentioned above, it is necessary to optimize process conditions . in particular, the composition of the etching gas and the values of such other process parameters as radio-frequency power, gas pressure, gas-flow rate, and duration of the process. Guidelines for determining optimum conditions can be obtained from experimental determination of etch rates as functions of these parameters. Etch-gas mixtures of BCl3 and Cl2, some also including Ar, have been found to offer a high degree of selectivity as needed for patterning of PbZr(1-x)Ti(x)O3 films on top of Ir electrode layers in thin-film capacitor structures. The selectivity is characterized by a ratio of approx.10:1 (rate of etching PbZr(1-x)Ti(x)O3 divided by rate of etching Ir and IrO(x)). At the time of reporting the information for this article

  2. Correlation of plasma characteristics to etch rate and via sidewall angle in a deep reactive ion etch system using Langmuir probe and optical emission spectroscopy

    SciTech Connect

    Koirala, S. P.; Awaah, I.; Burkett, S. L.; Gordon, M. H.

    2011-01-15

    A Langmuir probe and optical emission spectroscopy were used in a deep reactive ion etch system to correlate plasma parameters (atomic fluorine and argon emission, electron density, ion density, and electron average energy) with the etch rate and via sidewall angle. All data were obtained for coil powers ranging from 200 to 800 W, platen powers ranging from 7 to 16 W, and pressure ranging from 3.8 to 62 mTorr with constant SF{sub 6} and Ar flow rates of 112 and 18 SCCM (SCCM denotes cubic centimeter per minute at STP), respectively. Results indicate that there is a correlation with etch rate for all plasma parameters except for argon emission. For argon emission, the etch rate exhibits a double-valued relation where the etch rate can either increase or decrease with increasing argon emission intensity due to changes in pressure which affect the energy coupling efficiency. As expected, the etch rate increases for measured increases in fluorine emission, electron density, and ion density. The etch rate, however, decreases with increasing average electron energy due to collision processes. In contrast, no correlation is observed between any of the measured plasma parameters with sidewall angle. The last result is consistent with the idea that sidewall angle is primarily controlled by the passivation cycle as opposed to the etching cycle, where all the authors' data were obtained.

  3. Optimization of microwave-induced chemical etching for rapid development of neutron-induced recoil tracks in CR-39 detectors

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Tripathy, S. P.; Bandyopadhyay, T.

    2014-03-01

    A systematic investigation is carried out to optimize the recently established microwave-induced chemical etching (MICE) parameters for rapid development of neutron-induced recoil tracks in CR-39 detectors. Several combinations of all available microwave powers with different etching durations were analysed to determine the most suitable etching condition. The etching duration was found to reduce with increasing microwave power and the tracks were observed at about 18, 15, 12, and 6 min for 300, 450, 600 and 900 W of microwave powers respectively compared to a few hours in chemical etching (CE) method. However, for complete development of tracks the etching duration of 30, 40, 50 and 60 min were found to be suitable for the microwave powers of 900, 600, 450 and 300 W, respectively. Temperature profiles of the etchant for all the available microwave powers at different etching durations were generated to regulate the etching process in a controlled manner. The bulk etch rates at different microwave powers were determined by 2 methods, viz., gravimetric and removed thickness methods. A logarithmic expression was used to fit the variation of bulk etch rate with microwave power. Neutron detection efficiencies were obtained for all the cases and the results on track parameters obtained with MICE technique were compared with those obtained from another detector processed with chemical etching.

  4. Ion-beam-assisted etching of diamond

    NASA Technical Reports Server (NTRS)

    Efremow, N. N.; Geis, M. W.; Flanders, D. C.; Lincoln, G. A.; Economou, N. P.

    1985-01-01

    The high thermal conductivity, low RF loss, and inertness of diamond make it useful in traveling wave tubes operating in excess of 500 GHz. Such use requires the controlled etching of type IIA diamond to produce grating like structures tens of micrometers deep. Previous work on reactive ion etching with O2 gave etching rates on the order of 20 nm/min and poor etch selectivity between the masking material (Ni or Cr) and the diamond. An alternative approach which uses a Xe(+) beam and a reactive gas flux of NO2 in an ion-beam-assisted etching system is reported. An etching rate of 200 nm/min was obtained with an etching rate ratio of 20 between the diamond and an aluminum mask.

  5. A statistical approach to optimization of alumina etching in a high density plasma

    SciTech Connect

    Li Xiao; Gupta, Subhadra; Highsmith, Alton; Paranjpe, Ajit; Rook, Katrina

    2008-08-01

    Inductively coupled plasma (ICP) reactive ion etching of Al{sub 2}O{sub 3} with fluorine-based gas chemistry in a high density plasma reactor was carried out in an initial investigation aimed at data storage applications. A statistical design of experiments was implemented to optimize etch performance with respect to process variables such as ICP power, platen power, direct current (dc) bias, and pressure. Both soft photoresist masks and hard metal masks were investigated in terms of etch selectivity and surface properties. The reverse power dependence of dc bias on the ratio of ICP to platen power was elucidated. Etch mechanisms in terms of physical and ion enhanced chemical etchings were discussed. The F-based chemistry greatly enhances the etch rate of alumina compared to purely physical processes such as ion milling. Etch rates as high as 150 nm/min were achieved using this process. A practical process window was developed for high etch rates, with reasonable selectivity to hard masks, with the desired profile, and with low substrate bias for minimal damage.

  6. Enhancement of Efficiency of a Solar Cell Fabricated on Black Si Made by Inductively Coupled Plasma-Reactive Ion Etching Process: A Case Study of a n-CdS/p-Si Heterojunction Cell.

    PubMed

    Katiyar, Ajit K; Mukherjee, S; Zeeshan, M; Ray, Samit K; Raychaudhuri, A K

    2015-10-28

    We show that a significant enhancement of solar cell efficiency can be achieved in cells fabricated on black Si made using inductively coupled plasma-reactive ion etching (ICP-RIE). The ICP-RIE-fabricated black Si results in an array of vertically oriented defect-free Si nanocones (average height ∼150 nm; apex diameter ∼25 nm) exhibiting an average reflectance ≤2% over most of the relevant solar spectral range. The enabling role of the ultralow reflectance of the nanostructured black Si has been demonstrated using a heterojunction solar cell fabricated by depositing a n-type CdS film on p-Si nanocones followed by a transparent conducting coating of Al-doped ZnO (AZO). The fabricated n-CdS/p-Si heterojunction exhibits promising power conversion efficiency close to 3%, up from a mere efficient 0.15% for a similar cell fabricated on a planar Si. The effect of the fabrication process for the black Si on solar cell performance has been investigated through the measurements of carrier lifetime and surface recombination velocity. The accompanying model and simulation analysis shows that the conical structure leads to the effective dielectric constant varying smoothly from the value of the air at the top to the value of Si at the base over the length of the nanocone, leading to a substantial reduction of its reflectance.

  7. RAPID COMMUNICATION: High silicon etch rates by hot filament generated atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Wanka, H. N.; Schubert, M. B.

    1997-04-01

    The etching of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon by hot tungsten filament generated atomic hydrogen has been investigated. Room-temperature etch rates of 27 Å 0022-3727/30/8/002/img1 for amorphous and 20 Å 0022-3727/30/8/002/img1 for microcrystalline silicon have been achieved. Boron doping decreases the etch rate, whereas phosphorus doping does not affect it. No surface roughening occurs, even for the highest a-Si:H etch rates. In the initial phase of the etch process, however, a bond structure modification arises close to the surface. An increase of microcrystalline silicon etch rates towards the substrate/film interface reflects the coalescence of the microcrystalline nuclei. Hot filament atomic hydrogen etching provides high etch rates of amorphous and polycrystalline silicon with a high selectivity against metals and thermal oxide. Due to its simple setup and control, this kind of hydrogen etching is very interesting for applications in semiconductor technology where F- or Cl-etchants are to be avoided.

  8. Scanning electron microscopy evaluation of the effect of etching agents on human enamel surface.

    PubMed

    Zanet, Caio G; Arana-Chavez, Victor E; Fava, Marcelo

    2006-01-01

    Acid etching promotes microporosities on enamel surface, which provide a better bonding surface to adhesive materials. The purpose of this study was to comparatively analyze the microstructure of enamel surface after etching with 37% phosphoric acid or with two self-etching primers, Non-rinse conditioner (NRC) and Clearfil SE Bond (CSEB) using scanning electron microscopy. Thirty sound premolars were divided into 3 groups with ten teeth each: Group 1: the buccal surface was etched with 37% phosphoric acid for 15 seconds; Group 2: the buccal surface was etched with NRC for 20 seconds; Group 3: the buccal surface was etched with CSEB for 20 seconds. Teeth from Group 1 were rinsed with water; teeth from all groups were air-dried for 15 seconds. After that, all specimens were processed for scanning electron microscopy and analyzed in a Jeol 6100 SEM. The results showed deeper etching when the enamel surface was etched with 37% phosphoric acid, followed by NRC and CSEB. It is concluded that 37% phosphoric acid is still the best agent for a most effective enamel etching. PMID:16683674

  9. Improvement in etching rate for epilayer lift-off with surfactant

    NASA Astrophysics Data System (ADS)

    Wu, Fan-Lei; Horng, Ray-Hua; Lu, Jian-Heng; Chen, Chun-Li; Kao, Yu-Cheng

    2013-03-01

    In this study, the GaAs epilayer is quickly separated from GaAs substrate by epitaxial lift-off (ELO) process with mixture etchant solution. The HF solution mixes with surfactant as mixture etchant solution to etch AlAs sacrificial layer for the selective wet etching of AlAs sacrificial layer. Addiction surfactants etchant significantly enhance the etching rate in the hydrofluoric acid etching solution. It is because surfactant provides hydrophilicity to change the contact angle with enhances the fluid properties of the mixture etchant between GaAs epilayer and GaAs substrate. Arsine gas was released from the etchant solution because the critical reaction product in semiconductor etching is dissolved arsine gas. Arsine gas forms a bubble, which easily displaces the etchant solution, before the AlAs layer was undercut. The results showed that acetone and hydrofluoric acid ratio of about 1:1 for the fastest etching rate of 13.2 μm / min. The etching rate increases about 4 times compared with pure hydrofluoric acid, moreover can shorten the separation time about 70% of GaAs epilayer with GaAs substrate. The results indicate that etching ratio and stability are improved by mixture etchant solution. It is not only saving the epilayer and the etching solution exposure time, but also reducing the damage to the epilayer structure.

  10. Dry etch development of W/WSi short Gate MESFETs

    SciTech Connect

    Shul, R.J.; Sherwin, M.E.; Baca, A.G.; Zolper, J.C.; Rieger, D.J.

    1996-01-01

    The use of refractory metal thin films in the fabrication of high-speed, high-density GaAs field effect transistors (FETs) are prominent with applications as interconnects, via plugs, and ohmic and Schottky contacts. Tungsten and tungsten silicide can be used in a self-aligned gate process as the ion implantation mask during the formation of source and drain regions for metal-semiconductor FETs (MESFETs). The gate etch must be highly anisotropic to accurately define the implant region. Reactive ion etch (RIE) techniques have been used to etch W and WSi films in fluorine-based discharges. The etch mechanism tends to be very chemical and often results in severe undercutting of the feature due to the lateral attack of the refractory metal. The undercut is often so severe that critical dimensions are not maintained and gate profiles do not properly align to the implant region resulting in poor device characteristics. As device design rules shrink, the etch requirements and patterning techniques become even more critical.

  11. Wafer edge protection kit for MEMS and TSV Si-etching

    NASA Astrophysics Data System (ADS)

    Wieland, Robert; Nguyen, K.; Seidelmann, U.; Scholz, M.; Schrag, G.

    2015-05-01

    A new process kit for a SPTS Pegasus DRIE Si-Etch tool has been developed and tested for several different process regimes, e.g. bulk-Si cavity etching and TSV (through-Silicon-Via) etching with high aspect ratios <10:1, using the socalled Bosch process. Additionally, Si-etch back (recess etching) with a single step process has been tested as well. The especially developed "edge protection kit", consisting of Al2O3 material and optionally of PEEK material, covers the edge of a wafer, preventing it from being etched or even being etched away. However, placing such a part on top of the cathode, results in changes of the electric field distribution and the gas flow behavior compared to the standard process kit supplied by SPTS. The consequences may be altered Si-etch rates combined with changes of the tilt and side wall taper of the etched structures, mainly near the outside regions of the wafer. To this end, extensive investigations on the mask and bulk-Si etch rates, the tilt and taper angle of various MEMS test structures and their respective uniformity over the wafer surface have been performed. Additionally, simulations applying Comsol Multiphysics have been carried out to visualize the potential impact of the new process kit on the electrical field distribution. A simplex-optimization was carried out, varying the platen power and source power, in order to improve the tilt and to maintain the proper taper angle. One major advantage of the new process kit design compared to the original one is the reduction of movable parts to a minimum.

  12. Plasmoids for etching and deposition

    NASA Astrophysics Data System (ADS)

    Pothiraja, Ramasamy; Bibinov, Nikita; Awakowicz, Peter

    2014-11-01

    In this manuscript we show fascinating properties of plasmoids, which are known to be self-sustained plasma entities, and can exist without being in contact with any power supply. Plasmoids are produced in a filamentary discharge in a Ar/CH4 mixture with a high production rate of about 105 s-1. It is observed that plasmoids etch the solid amorphous hydrocarbon film with high efficiency. Energy density of the plasmoid, which is estimated on the basis of glowing area of plasmoids in the photographic image and sublimation enthalpy of the etched hydrocarbon film, amounts to about 90 J m-3. This value is much lower than the energy density of observed ball lightning (natural plasmoid). A very surprising property is an attraction between plasmoids, and the formation of plasmoid-groups. Because of this attractive force, carbon material, which is collected in plasmoids by etching of the hydrocarbon film or by propagation through a methane/argon gas mixture, is compressed into crystals.

  13. Profile etching for prefiguring X-ray mirrors.

    PubMed

    Liu, Chian; Qian, Jun; Assoufid, Lahsen

    2015-03-01

    A method to pre-shape mirror substrates through etching with a broad-beam ion source and a contoured mask is presented. A 100 mm-long elliptical cylinder substrate was obtained from a super-polished flat Si substrate with a 48 nm root-mean-square (r.m.s.) figure error and a 1.5 Å r.m.s. roughness after one profile-etching process at a beam voltage of 600 V without iteration. A follow-up profile coating can be used to achieve a final mirror. Profile etching and profile coating combined provide an economic way to make X-ray optics, such as nested Kirkpatrick-Baez mirrors.

  14. Study of etching rate uniformity in SRF cavities

    SciTech Connect

    Janardan Upadhyay, Svetozar Popovic, Leposova Vuskovic, H. Phillips, Anne-Marie Valente

    2012-07-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in the gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and chlorine concentration in the Argon/Chlorine gas mixtures.

  15. Method of plasma etching GA-based compound semiconductors

    DOEpatents

    Qiu, Weibin; Goddard, Lynford L.

    2013-01-01

    A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

  16. Fast and smooth etching of indium tin oxides in BCl{sub 3}/Cl{sub 2} inductively coupled plasmas

    SciTech Connect

    Andagana, H. B.; Cao, X. A.

    2010-03-15

    The etching characteristics of evaporation-deposited indium tin oxide (ITO) films in BCl{sub 3}/Cl{sub 2} inductively coupled plasmas have been studied. High etch rates >200 nm/min were obtained at large BCl{sub 3}/Cl{sub 2} gas flow ratios and high rf chuck powers, suggesting that the etching process is limited by sputter desorption of InCl{sub x} and SnCl{sub x} compounds. The addition of a small amount of CF{sub 4}, which acts as reducing agent, increased the etch rate by 30% and resulted in very smooth etched surfaces. It has also been found that the material crystallinity has a pronounced influence on ITO etch rate. ITO films annealed at 500 deg. C exhibited the maximum etch resistance.

  17. A Polymer-Rich Re-deposition Technique for Non-volatile Etching By-products in Reactive Ion Etching Systems

    NASA Astrophysics Data System (ADS)

    Limcharoen, A.; Pakpum, C.; Limsuwan, P.

    2013-07-01

    Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work. In this study, we propose a novel etching method called the polymer-rich re-deposition technique, used particularly for improving the etched sidewall where the re-deposition is able to accumulate. This technique works by allowing the accumulated re-deposition on the etched sidewall to have a higher polymer species than the new compounds in the non-volatile etching by-product. The polymer-rich re-deposition is easy to remove along with the photo-resist mask residual at the photo-resist strip step using an isopropyl alcohol-based solution. The traditional, additional cleaning process step used to remove the re-deposition material is not required anymore, so this reduces the overall processing time. The technique is demonstrated on an Al2O3-TiC substrate by C4F8 plasma, and the EDX spectrum confirms that the polymer re-deposition has C and F atoms as the dominant atoms, suggesting that it is a C—F polymer re-deposition.

  18. Etchant wettability in bulk micromachining of Si by metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Soo; Lee, Yeong Bahl; Khang, Dahl-Young

    2016-05-01

    Wet bulk micromachining of Si by metal-assisted chemical etching (MaCE) has successfully been demonstrated. Based on the mechanism of defective etching results from Ag and Au metal catalyst experiments, the wettability of etchant solution, in addition to metal type, has been found to have profound effect on the etching process. Addition of low surface tension co-solvent, ethanol in this work, into conventional etchant formulation has enabled complete wetting of etchant on surface, which prevents hydrogen bubble attachment on sample surface during the etching. The complete elimination of bubble attachment guarantees very uniform etch rate on all over the sample surface, and thus prevents premature fragmentation/rupture of catalyst metal layer. Under the optimized etching conditions, the MaCE could be done for up to 12 h without any noticeable film rupture and thus etching defects. Thanks to very smooth surface of the etched patterns, conformal contact and direct bonding of elastomer on such surface has been easily accomplished. The method demonstrated here can pave the way for application of simple, low-cost MaCE process in the bulk micromachining of Si for various applications.

  19. High-Density Plasma-Induced Etch Damage of GaN

    SciTech Connect

    Baca, A.G.; Han, J.; Lester, L.F.; Pearton, S.J.; Ren, F.; Shul, R.J.; Willison, C.G.; Zhang, L.; Zolper, J.C.

    1999-04-29

    Anisotropic, smooth etching of the group-III nitrides has been reported at relatively high rates in high-density plasma etch systems. However, such etch results are often obtained under high de-bias andlor high plasma flux conditions where plasma induced damage can be significant. Despite the fact that the group-III nitrides have higher bonding energies than more conventional III-V compounds, plasma-induced etch damage is still a concern. Attempts to minimize such damage by reducing the ion energy or increasing the chemical activity in the plasma often result in a loss of etch rate or anisotropy which significantly limits critical dimensions and reduces the utility of the process for device applications requiring vertical etch profiles. It is therefore necessary to develop plasma etch processes which couple anisotropy for critical dimension and sidewall profile control and high etch rates with low-damage for optimum device performance. In this study we report changes in sheet resistance and contact resistance for n- and p-type GaN samples exposed to an Ar inductively coupled plasma (ICP). In general, plasma-induced damage was more sensitive to ion bombardment energies as compared to plasma flux. In addition, p-GaN was typically more sensitive to plasma-induced damage as compared to n-GaN.

  20. Cryo-Etched Black Silicon for Use as Optical Black

    NASA Technical Reports Server (NTRS)

    Yee, Karl Y.; White, Victor E.; Mouroulis, Pantazis; Eastwood, Michael L.

    2011-01-01

    Stray light reflected from the surface of imaging spectrometer components in particular, the spectrometer slit degrade the image quality. A technique has been developed for rapid, uniform, and cost-effective black silicon formation based on inductively coupled plasma (ICP) etching at cryogenic temperatures. Recent measurements show less than 1-percent total reflectance from 350 2,500 nm of doped black silicon formed in this way, making it an excellent option for texturing of component surfaces for reduction of stray light. Oxygen combines with SF6 + Si etch byproducts to form a passivation layer atop the Si when the etch is performed at cryogenic temperatures. Excess flow of oxygen results in micromasking and the formation of black silicon. The process is repeatable and reliable, and provides control over etch depth and sidewall profile. Density of the needles can be controlled to some extent. Regions to be textured can be patterned lithographically. Adhesion is not an issue as the nanotips are part of the underlying substrate. This is in contrast to surface growth/deposition techniques such as carbon nanotubes (CNTs). The black Si surface is compatible with wet processing, including processing with solvents, the textured surface is completely inorganic, and it does not outgas. In radiometry applications, optical absorbers are often constructed using gold black or CNTs. This black silicon technology is an improvement for these types of applications.

  1. Etching method for photoresists or polymers

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R. (Inventor); Wydeven, Theodore J., Jr. (Inventor)

    1991-01-01

    A method for etching or removing polymers, photoresists, and organic contaminants from a substrate is disclosed. The method includes creating a more reactive gas species by producing a plasma discharge in a reactive gas such as oxygen and contacting the resulting gas species with a sacrificial solid organic material such as polyethylene or polyvinyl fluoride, reproducing a highly reactive gas species, which in turn etches the starting polymer, organic contaminant, or photoresist. The sample to be etched is located away from the plasma glow discharge region so as to avoid damaging the substrate by exposure to high energy particles and electric fields encountered in that region. Greatly increased etching rates are obtained. This method is highly effective for etching polymers such as polyimides and photoresists that are otherwise difficult or slow to etch downstream from an electric discharge in a reactive gas.

  2. Etching of glass microchips with supercritical water.

    PubMed

    Karásek, Pavel; Grym, Jakub; Roth, Michal; Planeta, Josef; Foret, František

    2015-01-01

    A novel method of etching channels in glass microchips with the most tunable solvent, water, was tested as an alternative to common hydrogen fluoride-containing etchants. The etching properties of water strongly depend on temperature and pressure, especially in the vicinity of the water critical point. The chips were etched at the subcritical, supercritical and critical temperature of water, and the resulting channel shape, width, depth and surface morphology were studied by scanning electron microscopy and 3D laser profilometry. Channels etched with the hot water were compared with the chips etched with standard hydrogen fluoride-containing solution. Depending on the water pressure and temperature, the silicate dissolved from the glass could be re-deposited on the channel surface. This interesting phenomenon is described together with the conditions necessary for its utilization. The results illustrate the versatility of pure water as a glass etching and surface morphing agent.

  3. Etching radical controlled gas chopped deep reactive ion etching

    DOEpatents

    Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

    2013-10-01

    A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

  4. Selective etching of silicon carbide films

    DOEpatents

    Gao, Di; Howe, Roger T.; Maboudian, Roya

    2006-12-19

    A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

  5. Evaluation of dry etching and defect repair of EUVL mask absorber layer

    NASA Astrophysics Data System (ADS)

    Abe, Tsukasa; Nishiguchi, Masaharu; Amano, Tsuyoshi; Motonaga, Toshiaki; Sasaki, Shiho; Mohri, Hiroshi; Hayashi, Naoya; Tanaka, Yuusuke; Nishiyama, Iwao

    2004-12-01

    EUVL mask process of absorber layer, buffer layer dry etching and defect repair were evaluated. TaGeN and Cr were selected for absorber layer and buffer layer, respectively. These absorber layer and buffer layer were coated on 6025 Qz substrate. Two dry etching processes were evaluated for absorber layer etching. One is CF4 plasma process and the other is Cl2 plasma process. Etch bias uniformity, selectivity, cross section profile and resist damage were evaluated for each process. Disadvantage of CF4 plasma process is low resist selectivity and Cl2 plasma process is low Cr selectivity. CF4 plasma process caused small absorber layer damage on isolate line and Cl2 plasma process caused Cr buffer layer damage. To minimize these damages overetch time was evaluated. Buffer layer process was also evaluated. Buffer layer process causes capping layer damage. Therefore, etching time was optimized. FIB-GAE and AFM machining were applied for absorber layer repair test. XeF2 gas was used for FIB-GAE. Good selectivity between absorber layer and buffer layer was obtained using XeF2 gas. However, XeF2 gas causes side etching of TaGeN layer. AFM machining repair technique was demonstrated for TaGeN layer repair.

  6. Method for dry etching of transition metals

    DOEpatents

    Ashby, C.I.H.; Baca, A.G.; Esherick, P.; Parmeter, J.E.; Rieger, D.J.; Shul, R.J.

    1998-09-29

    A method for dry etching of transition metals is disclosed. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorus-containing {pi}-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/{pi}-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the {pi}-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the {pi}-acceptor ligand for forming the volatile transition metal/{pi}-acceptor ligand complex.

  7. Method for dry etching of transition metals

    DOEpatents

    Ashby, Carol I. H.; Baca, Albert G.; Esherick, Peter; Parmeter, John E.; Rieger, Dennis J.; Shul, Randy J.

    1998-01-01

    A method for dry etching of transition metals. The method for dry etching of a transition metal (or a transition metal alloy such as a silicide) on a substrate comprises providing at least one nitrogen- or phosphorous-containing .pi.-acceptor ligand in proximity to the transition metal, and etching the transition metal to form a volatile transition metal/.pi.-acceptor ligand complex. The dry etching may be performed in a plasma etching system such as a reactive ion etching (RIE) system, a downstream plasma etching system (i.e. a plasma afterglow), a chemically-assisted ion beam etching (CAIBE) system or the like. The dry etching may also be performed by generating the .pi.-acceptor ligands directly from a ligand source gas (e.g. nitrosyl ligands generated from nitric oxide), or from contact with energized particles such as photons, electrons, ions, atoms, or molecules. In some preferred embodiments of the present invention, an intermediary reactant species such as carbonyl or a halide ligand is used for an initial chemical reaction with the transition metal, with the intermediary reactant species being replaced at least in part by the .pi.-acceptor ligand for forming the volatile transition metal/.pi.-acceptor ligand complex.

  8. Results from modeling and simulation of chemical downstream etch systems

    SciTech Connect

    Meeks, E.; Vosen, S.R.; Shon, J.W.; Larson, R.S.; Fox, C.A.; Buchenauer

    1996-05-01

    This report summarizes modeling work performed at Sandia in support of Chemical Downstream Etch (CDE) benchmark and tool development programs under a Cooperative Research and Development Agreement (CRADA) with SEMATECH. The Chemical Downstream Etch (CDE) Modeling Project supports SEMATECH Joint Development Projects (JDPs) with Matrix Integrated Systems, Applied Materials, and Astex Corporation in the development of new CDE reactors for wafer cleaning and stripping processes. These dry-etch reactors replace wet-etch steps in microelectronics fabrication, enabling compatibility with other process steps and reducing the use of hazardous chemicals. Models were developed at Sandia to simulate the gas flow, chemistry and transport in CDE reactors. These models address the essential components of the CDE system: a microwave source, a transport tube, a showerhead/gas inlet, and a downstream etch chamber. The models have been used in tandem to determine the evolution of reactive species throughout the system, and to make recommendations for process and tool optimization. A significant part of this task has been in the assembly of a reasonable set of chemical rate constants and species data necessary for successful use of the models. Often the kinetic parameters were uncertain or unknown. For this reason, a significant effort was placed on model validation to obtain industry confidence in the model predictions. Data for model validation were obtained from the Sandia Molecular Beam Mass Spectrometry (MBMS) experiments, from the literature, from the CDE Benchmark Project (also part of the Sandia/SEMATECH CRADA), and from the JDP partners. The validated models were used to evaluate process behavior as a function of microwave-source operating parameters, transport-tube geometry, system pressure, and downstream chamber geometry. In addition, quantitative correlations were developed between CDE tool performance and operation set points.

  9. Solid-liquid-vapor metal-catalyzed etching of lateral and vertical nanopores.

    PubMed

    Wallentin, Jesper; Deppert, Knut; Borgström, Magnus T

    2013-10-18

    Etching is an essential tool for the creation of nanostructures, where patterned metal structures can be used as masks. Here, we investigate HCl gas etching of InP substrates decorated with Au nanoparticles, and find that the etch rate is strongly increased at the Au-InP interfaces. The {111}A facets of the InP are preferentially etched. The metal nanoparticles follow in the etch direction, thereby creating nanopores. The size and position of the pores is controlled by the Au nanoparticles, and we measure nanopores as thin as 20 nm with an aspect ratio of 25:1. The direction of the nanopores is influenced by the temperature and the substrate orientation, which we use to demonstrate lateral, vertical and inclined nanopores. We explain the process by a solid-liquid-vapor model, in which the liquid metal particle catalyzes the dissolution of the solid InP. PMID:24060650

  10. Focused electron beam induced etching of titanium with XeF2.

    PubMed

    Schoenaker, F J; Córdoba, R; Fernández-Pacheco, R; Magén, C; Stéphan, O; Zuriaga-Monroy, C; Ibarra, M R; De Teresa, J M

    2011-07-01

    Titanium is a relevant technological material due to its extraordinary mechanical and biocompatible properties, its nanopatterning being an increasingly important requirement in many applications. We report the successful nanopatterning of titanium by means of focused electron beam induced etching using XeF(2) as a precursor gas. Etch rates up to 1.25 × 10(-3) µm(3) s(-1) and minimum pattern sizes of 80 nm were obtained. Different etching parameters such as beam current, beam energy, dwell time and pixel spacing are systematically investigated, the etching process being optimized by decreasing both the beam current and the beam energy. The etching mechanism is investigated by transmission electron microscopy. Potential applications in nanotechnology are discussed. PMID:21586811

  11. Electron flux controlled switching between electron beam induced etching and deposition

    NASA Astrophysics Data System (ADS)

    Toth, Milos; Lobo, Charlene J.; Hartigan, Gavin; Ralph Knowles, W.

    2007-03-01

    Electron beam induced deposition (EBID) and etching (EBIE) are promising methods for the fabrication of three-dimensional nanodevices, wiring of nanostructures, and repair of photolithographic masks. Here, we study simultaneous EBID and EBIE, and demonstrate an athermal electron flux controlled transition between material deposition and etching. The switching is observed when one of the processes has both a higher efficiency and a lower precursor partial pressure than the other. This is demonstrated in two technologically important systems: during XeF2-mediated etching of chrome on a photolithographic mask and during deposition and etching of carbonaceous films on a semiconductor surface. Simultaneous EBID and EBIE can be used to enhance the spatial localization of etch profiles. It plays a key role in reducing contamination buildup rates during low vacuum electron imaging and deposition of high purity nanostructures in the presence of oxygen-containing gases.

  12. Focused electron beam induced etching of titanium with XeF2

    NASA Astrophysics Data System (ADS)

    Schoenaker, F. J.; Córdoba, R.; Fernández-Pacheco, R.; Magén, C.; Stéphan, O.; Zuriaga-Monroy, C.; Ibarra, M. R.; De Teresa, J. M.

    2011-07-01

    Titanium is a relevant technological material due to its extraordinary mechanical and biocompatible properties, its nanopatterning being an increasingly important requirement in many applications. We report the successful nanopatterning of titanium by means of focused electron beam induced etching using XeF2 as a precursor gas. Etch rates up to 1.25 × 10 - 3 µm3 s - 1 and minimum pattern sizes of 80 nm were obtained. Different etching parameters such as beam current, beam energy, dwell time and pixel spacing are systematically investigated, the etching process being optimized by decreasing both the beam current and the beam energy. The etching mechanism is investigated by transmission electron microscopy. Potential applications in nanotechnology are discussed.

  13. Controlled fabrication of silicon nanowires via nanosphere lithograph and metal assisted chemical etching.

    PubMed

    Sun, Bo; Shi, Tielin; Sheng, Wenjun; Liao, Guanglan

    2013-08-01

    We investigated the controlled fabrication of uniform vertical aligned silicon nanowires with desired length, diameter and location by combining nanosphere lithograph and metal assisted chemical etching techniques. The close-packed polystyrene nanospheres array was obtained by self-assemble technique, followed by reactive ion etching to acquire a non-close-packed monolayer template. Subsequently, the template was used to create a metal film with nanoholes array, which enable the controlled fabrication of ordered silicon nanowires via metal assisted chemical etching technique. By adjusting the monolayer of polystyrene nanospheres and the conditions for the metal assisted chemical etching, we obtained uniform distributed silicon nanowires with desired morphology. The aspect ratio of the silicon nanowires can reach to about 86:1. Furthermore, we have obtained the double-layer silicon nanowires by slight modifying the process. The influences of various conditions during etching were also discussed for improving the controlled fabrication.

  14. Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals.

    PubMed

    Avci, Civan; Ariñez-Soriano, Javier; Carné-Sánchez, Arnau; Guillerm, Vincent; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2015-11-23

    Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

  15. Reactive ion etching of indium-tin oxide films by CCl4-based Inductivity Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Juneja, Sucheta; Poletayev, Sergey D.; Fomchenkov, Sergey; Khonina, Svetlana N.; Skidanov, Roman V.; Kazanskiy, Nikolay L.

    2016-08-01

    Indium tin oxide (ITO) films have been a subject of extensive studies in fabrication of micro-electronic devices for opto-electronic applications ranging from anti-reflection coatings to transparent contacts in photovoltaic devices. In this paper, a new and effective way of reactive ion etching of a conducting indium-tin oxide (ITO) film with Carbon tetrachloride (CCl4) has been investigated. CCl4 plasma containing an addition of gases mixture of dissociated argon and oxygen were used. Oxygen is added to increase the etchant percentage whereas argon was used for stabilization of plasma. The etching characteristics obtained with these gaseous mixtures were explained based on plasma etch chemistry and etching regime of ITO films. An etch rate as high as ∼20 nm/min can be achieved with a controlled process parameter such as power density, total flow rate, composition of reactive gases gas and pressure. Our Investigation represents some of the extensive work in this area.

  16. ALTERNATIVE TO CHROME ETCHING PROCESSES FOR METALS

    EPA Science Inventory

    Several industries, including the National Center for Manufacturing Science have initiated programs for chrome abatement. The programs, however, generally focus on chrome reduction by use of existing technologies and do not address the elimination of chrome in pretreatment proces...

  17. Crystallographic anisotropy of growth and etch rates of CVD diamond

    SciTech Connect

    Wolfer, M; Biener, J; El-dasher, B S; Biener, M M; Hamza, A V; Kriele, A; Wild, C

    2008-08-05

    The investigation of orientation dependent crystal growth and etch processes can provide deep insights into the underlying mechanisms and thus helps to validate theoretical models. Here, we report on homoepitaxial diamond growth and oxygen etch experiments on polished, polycrystalline CVD diamond wafers by use of electron backscatter diffraction (EBSD) and white-light interferometry (WLI). Atomic force microscopy (AFM) was applied to provide additional atomic scale surface morphology information. The main advantage of using polycrystalline diamond substrates with almost random grain orientation is that it allows determining the orientation dependent growth (etch) rate for different orientations within one experiment. Specifically, we studied the effect of methane concentration on the diamond growth rate, using a microwave plasma CVD process. At 1 % methane concentration a maximum of the growth rate near <100> and a minimum near <111> is detected. Increasing the methane concentration up to 5 % shifts the maximum towards <110> while the minimum stays at <111>. Etch rate measurements in a microwave powered oxygen plasma reveal a pronounced maximum at <111>. We also made a first attempt to interpret our experimental data in terms of local micro-faceting of high-indexed planes.

  18. Catalytic etching of monolayer graphene at low temperature via carbon oxidation.

    PubMed

    Jin, Jun Eon; Lee, Jae-Hyun; Choi, Jun Hee; Jang, Ho-Kyun; Na, Junhong; Whang, Dongmok; Kim, Do-Hyun; Kim, Gyu Tae

    2016-01-01

    In this work, an easy method to etch monolayer graphene is shown by catalytic oxidation in the presence of ZnO nanoparticles (NPs). The catalytic etching of monolayer graphene, which was transferred to the channel of field-effect transistors (FETs), was performed at low temperature by heating the FETs several times under an inert gas atmosphere (ZnO + C → Zn + CO or CO2). As the etching process proceeded, diverse etched structures in the shape of nano-channels and pits were observed under microscopic observation. To confirm the evolution of etching, current-voltage characteristics of monolayer graphene were measured after every step of etching by catalytic oxidation. As a result, the conductance of monolayer graphene decreased with the development of etched structures. This decrease in conductance was analyzed by percolation theory in a honeycomb structure. Finally, well-patterned graphene was obtained by oxidizing graphene under air in the presence of NPs, where Al was deposited on graphene as a mask for designed patterns. This method can substitute graphene etching via carbon hydrogenation using H2 at high temperature. PMID:26225821

  19. XeF2 vapor phase silicon etch used in the fabrication of movable SOI structures.

    SciTech Connect

    Wiwi, M.; Sanchez, Carlos Anthony; Plut, Thomas Alvin; Salazar, M.; Stevens, Jeffrey; Bauer, Todd M.; Ford, C.; Shul, Randy John; Grossetete, Grant David

    2010-10-01

    Vapor phase XeF{sub 2} has been used in the fabrication of various types of devices including MEMS, resonators, RF switches, and micro-fluidics, and for wafer level packaging. In this presentation we demonstrate the use of XeF{sub 2} Si etch in conjunction with deep reactive ion etch (DRIE) to release single crystal Si structures on Silicon On Insulator (SOI) wafers. XeF{sub 2} vapor phase etching is conducive to the release of movable SOI structures due to the isotropy of the etch, the high etch selectivity to silicon dioxide (SiO{sub 2}) and fluorocarbon (FC) polymer etch masks, and the ability to undercut large structures at high rates. Also, since XeF{sub 2} etching is a vapor phase process, stiction problems often associated with wet chemical release processes are avoided. Monolithic single crystal Si features were fabricated by etching continuous trenches in the device layer of an SOI wafer using a DRIE process optimized to stop on the buried SiO{sub 2}. The buried SiO{sub 2} was then etched to handle Si using an anisotropic plasma etch process. The sidewalls of the device Si features were then protected with a conformal passivation layer of either FC polymer or SiO{sub 2}. FC polymer was deposited from C4F8 gas precursor in an inductively coupled plasma reactor, and SiO{sub 2} was deposited by plasma enhanced chemical vapor deposition (PECVD). A relatively high ion energy, directional reactive ion etch (RIE) plasma was used to remove the passivation film on surfaces normal to the direction of the ions while leaving the sidewall passivation intact. After the bottom of the trench was cleared to the underlying Si handle wafer, XeF{sub 2} was used to isotropically etch the handle Si, thus undercutting and releasing the features patterned in the device Si layer. The released device Si structures were not etched by the XeF{sub 2} due to protection from the top SiO{sub 2} mask, sidewall passivation, and the buried SiO{sub 2} layer. Optimization of the XeF{sub 2

  20. Etch challenges for DSA implementation in CMOS via patterning

    NASA Astrophysics Data System (ADS)

    Pimenta Barros, P.; Barnola, S.; Gharbi, A.; Argoud, M.; Servin, I.; Tiron, R.; Chevalier, X.; Navarro, C.; Nicolet, C.; Lapeyre, C.; Monget, C.; Martinez, E.

    2014-03-01

    This paper reports on the etch challenges to overcome for the implementation of PS-b-PMMA block copolymer's Directed Self-Assembly (DSA) in CMOS via patterning level. Our process is based on a graphoepitaxy approach, employing an industrial PS-b-PMMA block copolymer (BCP) from Arkema with a cylindrical morphology. The process consists in the following steps: a) DSA of block copolymers inside guiding patterns, b) PMMA removal, c) brush layer opening and finally d) PS pattern transfer into typical MEOL or BEOL stacks. All results presented here have been performed on the DSA Leti's 300mm pilot line. The first etch challenge to overcome for BCP transfer involves in removing all PMMA selectively to PS block. In our process baseline, an acetic acid treatment is carried out to develop PMMA domains. However, this wet development has shown some limitations in terms of resists compatibility and will not be appropriated for lamellar BCPs. That is why we also investigate the possibility to remove PMMA by only dry etching. In this work the potential of a dry PMMA removal by using CO based chemistries is shown and compared to wet development. The advantages and limitations of each approach are reported. The second crucial step is the etching of brush layer (PS-r-PMMA) through a PS mask. We have optimized this step in order to preserve the PS patterns in terms of CD, holes features and film thickness. Several integrations flow with complex stacks are explored for contact shrinking by DSA. A study of CD uniformity has been addressed to evaluate the capabilities of DSA approach after graphoepitaxy and after etching.

  1. Charging free energy calculations using the Generalized Solvent Boundary Potential (GSBP) and periodic boundary condition: a comparative analysis using ion solvation and oxidation free energy in proteins.

    PubMed

    Lu, Xiya; Cui, Qiang

    2013-02-21

    Free energy simulations using a finite sphere boundary condition rather than a periodic boundary condition (PBC) are attractive in the study of very large biomolecular systems. To understand the quantitative impact of various approximations in such simulations, we compare charging free energies in both solution and protein systems calculated in a linear response framework with the Generalized Solvent Boundary Potential (GSBP) and PBC simulations. For simple ions in solution, we find good agreements between GSBP and PBC charging free energies, once the relevant correction terms are taken into consideration. For PBC simulations with the particle-mesh-Ewald for long-range electrostatics, the contribution (ΔG(P-M)) due to the use of a particle rather than molecule based summation scheme in real space is found to be significant, as pointed out by Hünenberger and co-workers. For GSBP, when the inner region is close to be charge neutral, the key correction is the overpolarization of water molecules at the inner/outer dielectric boundary; the magnitude of the correction (ΔG(s-pol)), however, is relatively small. For charging (oxidation) free energy in proteins, the situation is more complex, although good agreement between GSBP and PBC can still be obtained when care is exercised. The smooth dielectric boundary approximation inherent to GSBP tends to make significant errors when the inner region is featured with a high net charge. However, the error can be corrected with Poisson-Boltzmann calculations using snapshots from GSBP simulations in a straightforward and robust manner. Because of the more complex charge and solvent distributions, the magnitudes of ΔG(P-M) and ΔG(s-pol) in protein simulations appear to be different from those derived for solution simulations, leading to uncertainty in directly comparing absolute charging free energies from PBC and GSBP simulations for protein systems. The relative charging/oxidation free energies, however, are robust. With the

  2. Halogen-based plasma etching of novel field-effect transistor gate materials

    NASA Astrophysics Data System (ADS)

    Kiehlbaugh, Kasi Michelle

    Vacuum Beam Studies of Ruthenium Etching. Ru is known to have two volatile oxidation products, RuO3 and RuO4, although the etch rate is negligible when Ru is exposed to an O2 plasma discharge. The introduction of a small amount of additive gas, such as Cl2, has been shown to increase the Ru etch rate sixfold. The reason for this dramatic shift in etching is poorly understood, primarily because it is difficult if not impossible to study plasma-surface interactions in a plasma environment. The unique capabilities of the beam system have made it possible to explore the mechanism of Ru etching. It has been shown that under 500 eV Ar+ ion bombardment, the addition of O radicals lowered the etch rate by a factor of 2.5. This process was relatively insensitive to temperature over the range studied (room temperature to ˜175°C). It was also shown that O radicals alone spontaneously etched Ru at a very slow rate over the entire temperature range. Statistical Analysis of Polysilicon Etching and Gate Profile Evolution in Dual-Doped Polysilicon Gates. Polysilicon gate etching for the 90nm lithography node and below requires extremely precise control of the gate CD and profile. Generally speaking, the current requirement for Gate CD control is that the 3 sigma should less than ˜5nm for all gates, including across the chip, across the wafer, wafer-to-wafer, lot-to-lot, and tool-to-tool variations. Similarly, for gate sidewall angle control, the 3 sigma angle variation should be less than ˜1 degree, inclusive of all sources of variation. This is particularly challenging for technologies which employ dual-doped gates, since the chemistry and physics of the etching process induces a different profile evolution between gates with different doping. The goal of this project was to identify a parameter space where the differences in gate profile evolution across different polysilicon dopant types were minimized. Blanket etch rates and patterned wafers were used to determine the

  3. Charging effect simulation model used in simulations of plasma etching of silicon

    SciTech Connect

    Ishchuk, Valentyn; Volland, Burkhard E.; Hauguth, Maik; Rangelow, Ivo W.; Cooke, Mike

    2012-10-15

    Understanding the consequences of local surface charging on the evolving etching profile is a critical challenge in high density plasma etching. Deflection of the positively charged ions in locally varying electric fields can cause profile defects such as notching, bowing, and microtrenching. We have developed a numerical simulation model capturing the influence of the charging effect over the entire course of the etching process. The model is fully integrated into ViPER (Virtual Plasma Etch Reactor)-a full featured plasma processing simulation software developed at Ilmenau University of Technology. As a consequence, we show that local surface charge concurrently evolves with the feature profile to affect the final shape of the etched feature. Using gas chopping (sometimes called time-multiplexed) etch process for experimental validation of the simulation, we show that the model provides excellent fits to the experimental data and both, bowing and notching effects are captured-as long as the evolving profile and surface charge are simultaneously simulated. In addition, this new model explains that surface scallops, characteristic of gas chopping technique, are eroded and often absent in the final feature profile due to surface charging. The model is general and can be applied across many etching chemistries.

  4. Etching study of poled lithium tantalate crystal using wet etching technique with ultrasonic assistance

    NASA Astrophysics Data System (ADS)

    Gao, Z. D.; Wang, Q. J.; Zhang, Y.; Zhu, S. N.

    2008-02-01

    Utilizing the difference in etching rates of the positive and negative domains in an acid solution, domain pattern can be fabricated on the polarity surface of a congruent lithium tantalate crystal. Our results show that the ultrasonic agitation can improve the etching rate. An enhanced factor up to six was realized under a 50 W of ultrasonic power in a mixture with volumetric ratio of HF to H 2SO 4 at 1:2. The dependences of etching morphology on etching time and etching etchant for congruent lithium tantalate crystal were studied. The technique is applicable to fabricating three-dimensional microstructures on the surface of ferroelectric crystals.

  5. Etching with electron beam generated plasmas

    SciTech Connect

    Leonhardt, D.; Walton, S.G.; Muratore, C.; Fernsler, R.F.; Meger, R.A.

    2004-11-01

    A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen-argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was seen as gas composition went from pure oxygen to 70% argon, implying the resist removal mechanism in this system required the additional energy supplied by the ions. With silicon substrates at room temperature, mixtures of argon and sulfur hexafluoride etched approximately seven times faster (1375 nm/min) than mixtures of oxygen and sulfur hexafluoride ({approx}200 nm/min) with 200 eV ions, the difference is attributed to the passivation of the silicon by involatile silicon oxyfluoride (SiO{sub x}F{sub y}) compounds. At low incident ion energies, the Ar-SF{sub 6} mixtures showed a strong chemical (lateral) etch component before an ion-assisted regime, which started at {approx}75 eV. Etch rates were independent of the 0.5%-50% duty factors studied in this work.

  6. Note: electrochemical etching of sharp iridium tips.

    PubMed

    Lalanne, Jean-Benoît; Paul, William; Oliver, David; Grütter, Peter H

    2011-11-01

    We describe an etching procedure for the production of sharp iridium tips with apex radii of 15-70 nm, as determined by scanning electron microscopy, field ion microscopy, and field emission measurements. A coarse electrochemical etch followed by zone electropolishing is performed in a relatively harmless calcium chloride solution with high success rate.

  7. Plasma-etched nanostructures for optical applications (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Schulz, Ulrike; Rickelt, Friedrich; Munzert, Peter; Kaiser, Norbert

    2015-08-01

    A basic requirement for many optical applications is the reduction of Fresnel-reflections. Besides of interference coatings, nanostructures with sub-wavelength size as known from the eye of the night-flying moth can provide antireflective (AR) properties. The basic principle is to mix a material with air on a sub-wavelength scale to decrease the effective refractive index. To realize AR nanostructures on polymers, the self-organized formation of stochastically arranged antireflective structures using a low-pressure plasma etching process was studied. An advanced procedure involves the use of additional deposition of a thin oxide layer prior etching. A broad range of different structure morphologies exhibiting antireflective properties can be generated on almost all types of polymeric materials. For applications on glass, organic films are used as a transfer medium. Organic layers as thin film materials were evaluated to identify compounds suitable for forming nanostructures by plasma etching. The vapor deposition and etching of organic layers on glass offers a new possibility to achieve antireflective properties in a broad spectral range and for a wide range of light incidence.

  8. Surface Modification of Polymer Photoresists in Fluorocarbon Plasma Etching

    NASA Astrophysics Data System (ADS)

    Wang, Mingmei; Kushner, Mark

    2009-10-01

    In plasma etching of high aspect ratio (AR), nm sized features, erosion of polymer photoresist (PR) can perturb the feature profile (e.g., bowing). Although cross-linking of PR due to ion and VUV fluxes could make it more resistive to etching, typically the PR etch rate is too high to maintain the pattern when the AR is large (> 20). In dielectric plasma etching using fluorocarbon gases, one strategy to prevent PR erosion is to deposit a (CxFy)n polymer on its surface. This process may be enhanced in dc-augmented capacitively coupled plasmas (CCPs) by sputtering of Si and CxFy from the dc biased electrode. Dangling bonds generated on the PR surface by ion, photon or electron bombardment trap Si and CxFy radicals forming Si-C and C-C bonds. Sputtered Si atoms can also react with CxFy radicals to produce more reactive CxFy-1 radicals which are more easily incorporated into the PR. In this talk we discuss scaling laws for radical production derived from a computational investigation of a dc-augmented dual frequency CCP reactor sustained in Ar/C4F8/O2. Fluxes of Si radicals are produced by sputtering of the dc electrode. Rates of polymer deposition on and sputtering of PR, and consequences of PR erosion (and deposition) on feature profiles will be discussed.

  9. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    EPA Science Inventory

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  10. Controlling optical properties and surface morphology of dry etched porous silicon

    NASA Astrophysics Data System (ADS)

    Cheung, Maurice C.-K.; Roche, Philip J. R.; Hajj-Hassan, Mohamad; Kirk, Andrew G.; Mi, Zetian; Chodavarapu, Vamsy P.

    2011-01-01

    Porous silicon is a potentially useful substrate for fluorescence and scattering enhancement, with a large surface to volume ratio and thermal stability providing a potentially regenerable host matrix for sensor development. A simple process using XeF2 gas phase etching for creating porous silicon is explained. Moreover, how pores diameter can be controlled reproducibly with commensurate effects upon the silicon reflection and pore distribution is discussed. In previous work with this new system, it was clear that control on pore size and morphology was required and a systematic optimization of process conditions was performed to produce greater consistency of the result. The influence of the duration of the pre-etching processing in HF, concentration of the HF in the pre-etching process, and the XeF2 exposure time during the dry etching on surface morphology, pore size, and optical reflectance is explored.

  11. Low damage etching method of low-k material with a neutral beam for interlayer dielectric of semiconductor device

    SciTech Connect

    Kang, Seung Hyun; Kim, Jong Kyu; Lee, Sung Ho; Kim, Jin Woo; Yeom, Geun Young

    2015-03-15

    To reduce the cross-talk between nanoscale devices, low-k materials such as methyl silsesquioxane (MSQ), which is damaged easily during plasma etching, are introduced as an intermetallic dielectric material in addition to the use of copper as the conducting material for the reduction of parasitic resistance and capacitance. In this study, beam techniques such as neutral/ion beams were used in the etching of MSQ and the effect of these beam techniques on the reduction of the degradation of the MSQ were investigated. When MSQ was etched using the same CF{sub 4} etch gas at the similar etch rate as that used for conventional MSQ etching using inductively coupled plasmas (ICPs), the neutral/ion beam etching showed lower F contents and lower penetration depth of F, indicating decreased degradation by fluorination of MSQ during etching using the beam techniques. Especially, the neutral beam etching technique showed the lowest F contamination and the lower penetration depth of F among the etch methods. When the dielectric constant was measured after the etching of the same depth, the MSQ etched with the neutral beam showed the lowest change of the dielectric constant, while that etched using the ICP showed the highest change of dielectric constant. The lower degradation, that is, the lower chemical modification of MSQ material with the beam technique is believed to be related to the decreased concentration of radical species in the processing chamber reacting with the MSQ surface, while the lowest degradation using the neutral beam is believed to be due to the lower reaction rate of the reactive neutral compared to reactive ions.

  12. Mechanisms of Hydrocarbon Based Polymer Etch

    NASA Astrophysics Data System (ADS)

    Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

    2015-09-01

    Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

  13. Correlation between surface chemistry and ion energy dependence of the etch yield in multicomponent oxides etching

    SciTech Connect

    Berube, P.-M.; Poirier, J.-S.; Margot, J.; Stafford, L.; Ndione, P. F.; Chaker, M.; Morandotti, R.

    2009-09-15

    The influence of surface chemistry in plasma etching of multicomponent oxides was investigated through measurements of the ion energy dependence of the etch yield. Using pulsed-laser-deposited Ca{sub x}Ba{sub (1-x)}Nb{sub 2}O{sub 6} (CBN) and SrTiO{sub 3} thin films as examples, it was found that the etching energy threshold shifts toward values larger or smaller than the sputtering threshold depending on whether or not ion-assisted chemical etching is the dominant etching pathway and whether surface chemistry is enhancing or inhibiting desorption of the film atoms. In the case of CBN films etched in an inductively coupled Cl{sub 2} plasma, it is found that the chlorine uptake is inhibiting the etching reaction, with the desorption of nonvolatile NbCl{sub 2} and BaCl{sub 2} compounds being the rate-limiting step.

  14. Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma

    SciTech Connect

    Janardan Upadhyay, Larry Phillips, Anne-Marie Valente

    2011-09-01

    Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the measurement of the plasma parameters and for the holding of the Nb sample to be etched. The plasma properties at RF (100 MHz) and MW (2.45 GHz) frequencies are being measured with the help of electrical and optical probes at different pressures and RF power levels inside of this cavity. The niobium coupons placed on several holders around the cell are being etched simultaneously. The etching results will be presented at this conference.

  15. Suboxide/subnitride formation on Ta masks during magnetic material etching by reactive plasmas

    SciTech Connect

    Li, Hu; Muraki, Yu; Karahashi, Kazuhiro; Hamaguchi, Satoshi

    2015-07-15

    Etching characteristics of tantalum (Ta) masks used in magnetoresistive random-access memory etching processes by carbon monoxide and ammonium (CO/NH{sub 3}) or methanol (CH{sub 3}OH) plasmas have been examined by mass-selected ion beam experiments with in-situ surface analyses. It has been suggested in earlier studies that etching of magnetic materials, i.e., Fe, Ni, Co, and their alloys, by such plasmas is mostly due to physical sputtering and etch selectivity of the process arises from etch resistance (i.e., low-sputtering yield) of the hard mask materials such as Ta. In this study, it is shown that, during Ta etching by energetic CO{sup +} or N{sup +} ions, suboxides or subnitrides are formed on the Ta surface, which reduces the apparent sputtering yield of Ta. It is also shown that the sputtering yield of Ta by energetic CO{sup +} or N{sup +} ions has a strong dependence on the angle of ion incidence, which suggests a correlation between the sputtering yield and the oxidation states of Ta in the suboxide or subnitride; the higher the oxidation state of Ta, the lower is the sputtering yield. These data account for the observed etch selectivity by CO/NH{sub 3} and CH{sub 3}OH plasmas.

  16. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    SciTech Connect

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-12-07

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 micrometer inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits of focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon ‘halo’ deposition due to secondary electrons (SE) from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations.

  17. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    DOE PAGES

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-12-07

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 micrometer inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits ofmore » focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon ‘halo’ deposition due to secondary electrons (SE) from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations.« less

  18. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    NASA Astrophysics Data System (ADS)

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-12-01

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 μm inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits of focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon "halo" deposition due to secondary electrons from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations.

  19. Nanohole formation on AlGaAs surfaces by local droplet etching with gallium

    NASA Astrophysics Data System (ADS)

    Heyn, Ch.; Stemmann, A.; Hansen, W.

    2009-03-01

    We demonstrate the self-assembled generation of nanoholes on AlGaAs surfaces by local droplet etching (LDE). For the etching process, Ga is deposited on the surface, where liquid droplets are formed in a Volmer-Weber-like growth mode. The etching takes place locally at the interface between droplets and substrate and removes a significant amount of substrate material. The structural properties of the LDE nanoholes are studied with atomic force microscopy as function of etching temperature and Ga coverage. A bimodal depth distribution with flat and deep holes is observed. The formation of flat holes can be almost suppressed by optimized etching parameters. The depth of deep holes was adjusted by the process parameters up to a maximum depth of 15 nm. The density of deep holes is in the range 5×10 -7-1×10 -8 cm -2 and depends only slightly on the etching parameters. However, the density can be significantly increased by repeated etching.

  20. Ultradeep fused silica glass etching with an HF-resistant photosensitive resist for optical imaging applications

    NASA Astrophysics Data System (ADS)

    Nagarah, John M.; Wagenaar, Daniel A.

    2012-03-01

    Microfluidic and optical sensing platforms are commonly fabricated in glass and fused silica (quartz) because of their optical transparency and chemical inertness. Hydrofluoric acid (HF) solutions are the etching media of choice for deep etching into silicon dioxide substrates, but processing schemes become complicated and expensive for etching times greater than 1 h due to the aggressiveness of HF migration through most masking materials. We present here etching into fused silica more than 600 µm deep while keeping the substrate free of pits and maintaining a polished etched surface suitable for biological imaging. We utilize an HF-resistant photosensitive resist (HFPR) which is not attacked in 49% HF solution. Etching characteristics are compared for substrates masked with the HFPR alone and the HFPR patterned on top of Cr/Au and polysilicon masks. We used this etching process to fabricate suspended fused silica membranes, 8-16 µm thick, and show that imaging through the membranes does not negatively affect image quality of fluorescence microscopy of biological tissue. Finally, we realize small through-pore arrays in the suspended membranes. Such devices will have applications in planar electrophysiology platforms, especially where optical imaging is required.

  1. High Speed Si Etching with ClF{sub 3} Cluster Injection

    SciTech Connect

    Seki, T.; Yoshino, Y.; Senoo, T.; Koike, K.; Ninomiya, S.; Matsuo, J.; Aoki, T.

    2011-01-07

    The reactive gas cluster injection process is an etching method that uses a neutral cluster beam without plasma. ClF{sub 3}-Ar neutral cluster was generated and the Si etching characteristics with this beam were investigated. ClF{sub 3} is very high reactive gas. Adiabatic expansion of a high-pressure gas through a conical nozzle is utilized for the formation of cluster beams. The source gas was a mixture of ClF{sub 3}(6%) with Ar (94%). The etching rate increased with source gas pressure nonlinearly, and the etching rate achieved more than 30 {mu}m/min at 0.85 MPa. Although the irradiation energy was very low (<1 eV/atom or molecule), the chemical etching was enhanced with cluster impacts and the cluster bombarded area on the surface was etched selectively. These results indicated that high speed anisotropic etching with low damage can be realized with the ClF{sub 3} cluster injection process.

  2. Using an energized oxygen micro-jet for improved graphene etching by focused electron beam

    SciTech Connect

    Kim, Songkil; Henry, Mathias; Fedorov, Andrei G.

    2015-12-07

    We report on an improved Focused Electron Beam Induced Etching (FEBIE) process, which exploits heated oxygen delivery via a continuous supersonic micro-jet resulting in faster graphene patterning and better etch feature definition. Positioning a micro-jet in close proximity to a graphene surface with minimal jet spreading due to a continuous regime of gas flow at the exit of the 10 μm inner diameter capillary allows for focused exposure of the surface to reactive oxygen at high mass flux and impingement energy of a supersonic gas stream localized to a small etching area exposed to electron beam. These unique benefits of focused supersonic oxygen delivery to the surface enable a dramatic increase in the etch rate of graphene with no parasitic carbon “halo” deposition due to secondary electrons from backscattered electrons (BSE) in the area surrounding the etched regions. Increase of jet temperature via local nozzle heating provides means for enhancing kinetic energy of impinging oxygen molecules, which further speed up the etch, thus minimizing the beam exposure time and required electron dose, before parasitic carbon film deposition due to BSE mediated decomposition of adsorbed hydrocarbon contaminants has a measurable impact on quality of graphene etched features. Interplay of different physical mechanisms underlying an oxygen micro-jet assisted FEBIE process is discussed with support from experimental observations.

  3. Localized etching of polymer films using an atmospheric pressure air microplasma jet

    NASA Astrophysics Data System (ADS)

    Guo, Honglei; Liu, Jingquan; Yang, Bin; Chen, Xiang; Yang, Chunsheng

    2015-01-01

    A direct-write process device based on the atmospheric pressure air microplasma jet (AμPJ) has been developed for the localized etching of polymer films. The plasma was generated by the air discharge ejected out through a tip-nozzle (inner diameter of 100 μm), forming the microplasma jet. The AμPJ was capable of reacting with the polymer surface since it contains a high concentration of oxygen reactive species and thus resulted in the selective removal of polymer films. The experimental results demonstrated that the AμPJ could fabricate different microstructures on a parylene-C film without using any masks or causing any heat damage. The etch rate of parylene-C reached 5.1 μm min-1 and microstructures of different depth and width could also be realized by controlling two process parameters, namely, the etching time and the distance between the nozzle and the substrate. In addition, combining XPS analysis and oxygen-induced chemical etching principles, the potential etching mechanism of parylene-C by the AμPJ was investigated. Aside from the etching of parylene-C, micro-holes on the photoresist and polyimide film were successfully created by the AμPJ. In summary, maskless pattern etching of polymer films could be achieved using this AμPJ.

  4. Dry etching of CdTe/GaAs epilayers using CH{sub 4}H{sub 2} gas mixtures

    SciTech Connect

    Neswal, M.; Gresslehner, K.H.; Lischka, K.

    1993-05-01

    A CH{sub 4}/H{sub 2} gas mixture has been used for the dry etching of (100) and (111) oriented CdTe epilayers in a barrel reactor. The effects of various process parameters on etch rate and surface morphology were studied with special attention paid to the gas composition and the total chamber pressure as well as the crystallographic orientation of the sample. Clear evidence is found for both isotropic and preferential etching along crystalolographic planes depending on the set of etch parameters used. 14 refs., 7 figs.

  5. Determination of nuclear tracks parameters on sequentially etched PADC detectors

    NASA Astrophysics Data System (ADS)

    Horwacik, Tomasz; Bilski, Pawel; Koerner, Christine; Facius, Rainer; Berger, Thomas; Nowak, Tomasz; Reitz, Guenther; Olko, Pawel

    Polyallyl Diglycol Carbonate (PADC) detectors find many applications in radiation protection. One of them is the cosmic radiation dosimetry, where PADC detectors measure the linear energy transfer (LET) spectra of charged particles (from protons to heavy ions), supplementing TLD detectors in the role of passive dosemeter. Calibration exposures to ions of known LET are required to establish a relation between parameters of track observed on the detector and LET of particle creating this track. PADC TASTRAK nuclear track detectors were exposed to 12 C and 56 Fe ions of LET in H2 O between 10 and 544 keV/µm. The exposures took place at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan in the frame of the HIMAC research project "Space Radiation Dosimetry-Ground Based Verification of the MATROSHKA Facility" (20P-240). Detectors were etched in water solution of NaOH with three different temperatures and for various etching times to observe the appearance of etched tracks, the evolution of their parameters and the stability of the etching process. The applied etching times (and the solution's concentrations and temperatures) were: 48, 72, 96, 120 hours (6.25 N NaOH, 50 O C), 20, 40, 60, 80 hours (6.25 N NaOH, 60 O C) and 8, 12, 16, 20 hours (7N NaOH, 70 O C). The analysis of the detectors involved planimetric (2D) measurements of tracks' entrance ellipses and mechanical measurements of bulk layer thickness. Further track parameters, like angle of incidence, track length and etch rate ratio were then calculated. For certain tracks, results of planimetric measurements and calculations were also compared with results of optical track profile (3D) measurements, where not only the track's entrance ellipse but also the location of the track's tip could be directly measured. All these measurements have been performed with the 2D/3D measurement system at DLR. The collected data allow to create sets of V(LET in H2 O) calibration curves suitable for short, intermediate and

  6. Role of metal nanoparticles on porosification of silicon by metal induced etching (MIE)

    NASA Astrophysics Data System (ADS)

    Saxena, Shailendra K.; Yogi, Priyanka; Yadav, Pooja; Mishra, Suryakant; Pandey, Haardik; Rai, Hari Mohan; Kumar, Vivek; Sagdeo, Pankaj R.; Kumar, Rajesh

    2016-06-01

    Porosification of silicon (Si) by metal induced etching (MIE) process has been studied here to understand the etching mechanism. The etching mechanism has been discussed on the basis of electron transfer from Si to metal ion (Ag+) and metal to H2O2. Role of silver nanoparticles (AgNPs) in the etching process has been investigated by studying the effect of AgNPs coverage on surface porosity. A quantitative analysis of SEM images, done using Image J, shows a direct correlation between AgNPs coverage and surface porosity after the porosification. Density of Si nanowires (NWs) also varies as a function of AgNPs fractional coverage which reasserts the fact that AgNPs governs the porosification process during MIE. The Raman and PL spectrum show the presence of Si NSs in the samples.

  7. Halogens on Semiconductor Surfaces: Adsorption, Oxidation, and Etching.

    NASA Astrophysics Data System (ADS)

    Stepniak, Frank

    This dissertation presents studies of Si, GaAs, and InP surfaces following exposure to the halogens Cl _2 and Br_2. Synchrotron radiation photoemission is used to investigate the oxidation states of Si near the Si/SiO_2 interface as a function of Cl_2 exposure. Oxidation of highly ordered surfaces shows no dependence of the oxidation state concentration on Cl_2 inclusion in the gas mixture. For less-than-ideal Si surfaces, oxidation with O_2 -only results in a broader transition region, and presumably, inferior electrical properties. The addition of Cl_2 in the oxidizing gas reduced the concentration of intermediate oxides by a factor of two for these disordered starting Si surfaces. A new feature is also measured from Cl-Si bonds that we associate with passivation of Si defects at the oxide interface. The adsorption and reactivity of Br_2 and Cl_2 on GaAs(110) and InP(110) was studied in the temperature range of 25 K < T < 625 K with photoemission spectroscopy and scanning tunneling microscopy. Initial halogen adsorption was dissociative at all temperatures and we find that a simple model where the halogen atoms bond to a single Ga or As surface site can not account for the complex surface chemistry and morphology. Thermally-activated etching was observed after warming a surface with chemisorbed Br or Cl. Etching resulted from the formation and eventual temperature dependent desorption of the trihalides of Ga and As. For halogen exposures where T < 650 K, monohalide-like surface bonding persist during the etching process and the etched surface is rough. For T > 700 K, the surface is essentially free of halogen and etching occurs in a nearly layer-by-layer fashion.

  8. Nanograss and nanostructure formation on silicon using a modified deep reactive ion etching

    SciTech Connect

    Mehran, M.; Mohajerzadeh, S.; Sanaee, Z.; Abdi, Y.

    2010-05-17

    Silicon nanograss and nanostructures are realized using a modified deep reactive ion etching technique on both plane and vertical surfaces of a silicon substrate. The etching process is based on a sequential passivation and etching cycle, and it can be adjusted to achieve grassless high aspect ratio features as well as grass-full surfaces. The incorporation of nanostructures onto vertically placed parallel fingers of an interdigital capacitive accelerometer increases the total capacitance from 0.45 to 30 pF. Vertical structures with features below 100 nm have been realized.

  9. Plasma etching in a multipolar discharge

    NASA Astrophysics Data System (ADS)

    Wicker, T. E.; Mantei, T. D.

    1985-03-01

    Etching of silicon and SiO2 has been investigated in a dc plasma discharge confined by a multipolar surface magnetic field layer. The reactive plasma is produced by primary ionizing electrons drawn from heated tungsten filaments and confined by permanent magnets. Electrical probe measurements show that a uniform high-density plasma (1010-1011 cm-3) is sustained in SF6-O2 at very low pressure (0.2-2.0×10-3 Torr). Substrates are biased independently of plasma production by a low-frequency alternating voltage (0-400 V) applied to the substrate through a blocking capacitor. Anisotropic profiles are etched into Si in SF6-20% O2 with etch rates in excess of 1 μm/min at 2×10-3 Torr. The etch rate increases with increasing primary electron current (up to 3 A) and energy (up to 60 eV), gas pressure (up to 2.0×10-3 Torr), substrate bias voltage, and the addition of up to 20% O2. For higher ionizing electron energies (>60 eV) and higher gas pressure (>2.0×10-3 Torr), etching is partially blocked by residue formation. The etch anisotropy depends mainly on substrate bias, increasing for higher values of bias voltage. The Si:SiO2 etch selectivity is typically 10-20, becoming large with decreasing substrate bias and plasma ion density.

  10. Nanoparticle-based etching of silicon surfaces

    DOEpatents

    Branz, Howard; Duda, Anna; Ginley, David S.; Yost, Vernon; Meier, Daniel; Ward, James S.

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  11. Etch Characteristics of GaN using Inductively Coupled Cl{sub 2} Plasma Etching

    SciTech Connect

    Rosli, Siti Azlina; Aziz, A. Abdul

    2008-05-20

    In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl{sub 2}/Ar plasmas were investigated. It has shown that the results of a study of inductively coupled plasma (ICP) etching of gallium nitride by using Cl{sub 2}/Ar is possible to meet the requirement (anisotropy, high etch rate and high selectivity), simultaneously. We have investigated the etching rate dependency on the percentage of Argon in the gas mixture, the total pressure and DC voltage. We found that using a gas mixture with 20 sccm of Ar, the optimum etch rate of GaN was achieved. The etch rate were found to increase with voltage, attaining a maximum rate 2500 A/min at -557 V. The addition of an inert gas, Ar is found to barely affect the etch rate. Surface morphology of the etched samples was verified by scanning electron microscopy and atomic force microscopy. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer.

  12. The Effect of HF/NH4F Etching on the Morphology of Surface Fractures on Fused Silica

    SciTech Connect

    Wong, L; Suratwala, T; Feit, M D; Miller, P E; Steele, R A

    2008-04-03

    function of etch time. The initial removal rate for the ground surface was typically 3.5 x the bulk etch rate. The evolving morphology of ground surfaces during etching was simulated using an isotropic finite difference model. This model illustrates the importance that the initial distributions of fracture sizes and spatial locations have on the evolution of roughness and the rate at which material is removed during the etching process. The etching of ground surfaces can be used during optical fabrication to convert subsurface damage into surface roughness thereby reducing the time required to produce polished surfaces that are free of subsurface damage.

  13. Solid-Liquid-Vapor Etching of Semiconductor Nanowires.

    PubMed

    Hui, Ho Yee; Filler, Michael A

    2015-10-14

    The vapor-liquid-solid (VLS) mechanism enables the bottom-up, or additive, growth of semiconductor nanowires. Here, we demonstrate a reverse process, whereby catalyst atoms are selectively removed from the eutectic catalyst droplet. This process, which is driven by the dicarbonyl precursor 2,3-butanedione, results in axial nanowire etching. Experiments as a function of substrate temperature, etchant flow rate, and nanowire diameter support a solid-liquid-vapor (SLV) mechanism. An etch model with reaction at the liquid-vapor interface as the rate-limiting step is consistent with our experiments. These results identify a new mechanism to in situ tune the concentration of semiconductor atoms in the catalyst droplet. PMID:26383971

  14. Personnel neutron dosimetry using hot, low-frequency electrochemical etching

    NASA Astrophysics Data System (ADS)

    Hankins, D. E.; Homann, S. G.; Davis, J. M.

    1985-09-01

    We have developed an electrochemical-etch procedure for the processing of large numbers of CR-39 dosimeters. Specially designed Homann-Type chambers can etch up to 24 CR-39 chips, or foils, at one time. In our two-step procedure, the second step, called blow-up, increases the tracks' size and makes them relatively uniform. The energy response is fairly flat from approx. 150 keV to 4.5 MeV, but drops by about a factor of three in the 13 to 16 MeV range. The sensitivity of the dosimetry system is 6 tracks/mrem with a background of 8 mrem, giving a lower limit of sensitivity of approximately 10 mrem for the dosimeter (when three foils are used). Because greater numbers of CR-39 foils can be accommodated at any one time, our procedure is quite efficient for operations with large numbers of dosimeters to be processed.

  15. Surface engineering on CeO2 nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation

    NASA Astrophysics Data System (ADS)

    Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

    2015-07-01

    Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce3+ fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications. Electronic supplementary information (ESI) available: Diameter distributions of as-prepared and etched samples, optical images, specific catalytic data of CO oxidation and comparison of CO oxidation. See DOI: 10.1039/c5nr01846c

  16. Dry etching method for compound semiconductors

    DOEpatents

    Shul, Randy J.; Constantine, Christopher

    1997-01-01

    A dry etching method. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators.

  17. Dry etching method for compound semiconductors

    DOEpatents

    Shul, R.J.; Constantine, C.

    1997-04-29

    A dry etching method is disclosed. According to the present invention, a gaseous plasma comprising, at least in part, boron trichloride, methane, and hydrogen may be used for dry etching of a compound semiconductor material containing layers including aluminum, or indium, or both. Material layers of a compound semiconductor alloy such as AlGaInP or the like may be anisotropically etched for forming electronic devices including field-effect transistors and heterojunction bipolar transistors and for forming photonic devices including vertical-cavity surface-emitting lasers, edge-emitting lasers, and reflectance modulators. 1 fig.

  18. Method of sputter etching a surface

    DOEpatents

    Henager, Jr., Charles H.

    1984-01-01

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion.

  19. Method of sputter etching a surface

    DOEpatents

    Henager, C.H. Jr.

    1984-02-14

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion. 4 figs.

  20. Experimental analysis of the surface roughness evolution of etched glass for micro/nanofluidic devices

    NASA Astrophysics Data System (ADS)

    Ren, J.; Ganapathysubramanian, B.; Sundararajan, S.

    2011-02-01

    Roughness of channel surfaces, both deterministic and random, is known to affect the fluid flow behavior in micro/nanoscale fluidic devices. This has relevance particularly for applications involving non-Newtonian fluids, such as in biomedical lab-on-chip devices. While several studies have investigated effects of relative large, deterministic surface structures on fluid flow, the effect of random roughness on microfluidic flow remains relatively unexplored. In this study, the effects of processing conditions for wet etching of glass including etching time and etching orientation on centre-line average (Ra) and the autocorrelation length (ACL) were investigated. Statistical distribution of the roughness was also studied. Results indicated that ACL can be tailored in the range of 1-4 µm by changing etching time in horizontal etching while Ra was found to increase weakly with etching time in all three etching orientations. Analysis of the experimental data using the Kolmogorov-Smirnov goodness-of-fit hypothesis test shows that the glass surface roughness does not follow a Gaussian distribution, as is typically assumed in the literature. Instead, the T location-scale distribution fits the roughness data with 1.11% error. These results provide promising insights into tailoring surface roughness for improving microfluidic devices.

  1. Microstructuring of Si(100) by light induced dry etching in the VUV

    NASA Astrophysics Data System (ADS)

    Streller, U.; Krabbe, A.; Raaf, H.; Schwentner, N.

    1998-02-01

    Light-induced dry etching of Si(100) in the VUV range using synchrotron radiation (SR) and a halogen-containing gas (XeF2) has been investigated with respect to selectivity, anisotropy, quantum efficiency, optimal wavelength, spatial resolution and quality of the photochemical etching processes. Microstructuring of Si with XeF2can be optimized to achieve etched structures in the sub-micrometre range by increasing the contrast in choosing a wavelength with minimal unselective etching. The strength of unselective etching is strongly wavelength dependent and follows the XeF2gas phase absorption coefficient. Fragments from dissociation of the XeF2reach the Si surface and thus cause unselective etching. Optimal dry etching occurs for wavelengths around 120 nm because the selectivity is high due to an excitation of a surface layer and also the quantum efficiency is very large. An efficiency of 10 removed Si atoms per incoming photon, which exceeds that in the visible spectral range by more than four orders of magnitude, combined with the higher spatial resolution at 120 nm compared to the conventional excimer laser and I-line wavelengths and the availability of optical materials for imaging present a perspective for generating line densities in the Gbit range.

  2. A deep etching mechanism for trench-bridging silicon nanowires.

    PubMed

    Tasdemir, Zuhal; Wollschläger, Nicole; Österle, Werner; Leblebici, Yusuf; Alaca, B Erdem

    2016-03-01

    Introducing a single silicon nanowire with a known orientation and dimensions to a specific layout location constitutes a major challenge. The challenge becomes even more formidable, if one chooses to realize the task in a monolithic fashion with an extreme topography, a characteristic of microsystems. The need for such a monolithic integration is fueled by the recent surge in the use of silicon nanowires as functional building blocks in various electromechanical and optoelectronic applications. This challenge is addressed in this work by introducing a top-down, silicon-on-insulator technology. The technology provides a pathway for obtaining well-controlled silicon nanowires along with the surrounding microscale features up to a three-order-of-magnitude scale difference. A two-step etching process is developed, where the first shallow etch defines a nanoscale protrusion on the wafer surface. After applying a conformal protection on the protrusion, a deep etch step is carried out forming the surrounding microscale features. A minimum nanowire cross-section of 35 nm by 168 nm is demonstrated in the presence of an etch depth of 10 μm. Nanowire cross-sectional features are characterized via transmission electron microscopy and linked to specific process steps. The technology allows control on all dimensional aspects along with the exact location and orientation of the silicon nanowire. The adoption of the technology in the fabrication of micro and nanosystems can potentially lead to a significant reduction in process complexity by facilitating direct access to the nanowire during surface processes such as contact formation and doping.

  3. A deep etching mechanism for trench-bridging silicon nanowires

    NASA Astrophysics Data System (ADS)

    Tasdemir, Zuhal; Wollschläger, Nicole; Österle, Werner; Leblebici, Yusuf; Erdem Alaca, B.

    2016-03-01

    Introducing a single silicon nanowire with a known orientation and dimensions to a specific layout location constitutes a major challenge. The challenge becomes even more formidable, if one chooses to realize the task in a monolithic fashion with an extreme topography, a characteristic of microsystems. The need for such a monolithic integration is fueled by the recent surge in the use of silicon nanowires as functional building blocks in various electromechanical and optoelectronic applications. This challenge is addressed in this work by introducing a top-down, silicon-on-insulator technology. The technology provides a pathway for obtaining well-controlled silicon nanowires along with the surrounding microscale features up to a three-order-of-magnitude scale difference. A two-step etching process is developed, where the first shallow etch defines a nanoscale protrusion on the wafer surface. After applying a conformal protection on the protrusion, a deep etch step is carried out forming the surrounding microscale features. A minimum nanowire cross-section of 35 nm by 168 nm is demonstrated in the presence of an etch depth of 10 μm. Nanowire cross-sectional features are characterized via transmission electron microscopy and linked to specific process steps. The technology allows control on all dimensional aspects along with the exact location and orientation of the silicon nanowire. The adoption of the technology in the fabrication of micro and nanosystems can potentially lead to a significant reduction in process complexity by facilitating direct access to the nanowire during surface processes such as contact formation and doping.

  4. Comparative time-resolved study of the XeF2 etching of Mo and Si

    NASA Astrophysics Data System (ADS)

    Veyan, J.-F.; Aureau, D.; Gogte, Y.; Campbell, P.; Yan, X.-M.; Chabal, Y. J.

    2010-12-01

    In situ and time-resolved infrared absorption spectroscopic measurements reveal that, under typical processing conditions (˜300 K, approximately Torr pressures), XeF2 reacts efficiently but very differently with Mo and Si substrates. This kinetic study of the surface etching processes, based on the time evolution of both reactants and products, demonstrates that the mechanisms for Mo and Si etching are different. While XeF2 produces substantial roughening and a thick fluorosilyl layer on the crystalline Si surface (>200 nm), it only reacts with the surface atoms of amorphous Mo with substantially slower kinetics. The measured kinetics are quantified by simulation and the final profile experimentally obtained on etched Si surface is shown to be consistent with a recent theoretical study of the characteristic diffusion-controlled etching of silicon.

  5. Silicon etching using only Oxygen at high temperature: An alternative approach to Si micro-machining on 150 mm Si wafers

    NASA Astrophysics Data System (ADS)

    Chai, Jessica; Walker, Glenn; Wang, Li; Massoubre, David; Tan, Say Hwa; Chaik, Kien; Hold, Leonie; Iacopi, Alan

    2015-12-01

    Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free, and high etch rate uniformity across a wafer. In addition, this alternative O2-based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity (>1000:1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts.

  6. Silicon etching using only Oxygen at high temperature: An alternative approach to Si micro-machining on 150 mm Si wafers.

    PubMed

    Chai, Jessica; Walker, Glenn; Wang, Li; Massoubre, David; Tan, Say Hwa; Chaik, Kien; Hold, Leonie; Iacopi, Alan

    2015-01-01

    Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free, and high etch rate uniformity across a wafer. In addition, this alternative O2-based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity (>1000:1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts. PMID:26634813

  7. Silicon etching using only Oxygen at high temperature: An alternative approach to Si micro-machining on 150 mm Si wafers.

    PubMed

    Chai, Jessica; Walker, Glenn; Wang, Li; Massoubre, David; Tan, Say Hwa; Chaik, Kien; Hold, Leonie; Iacopi, Alan

    2015-12-04

    Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free, and high etch rate uniformity across a wafer. In addition, this alternative O2-based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity (>1000:1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts.

  8. Silicon etching using only Oxygen at high temperature: An alternative approach to Si micro-machining on 150 mm Si wafers

    PubMed Central

    Chai, Jessica; Walker, Glenn; Wang, Li; Massoubre, David; Tan, Say Hwa; Chaik, Kien; Hold, Leonie; Iacopi, Alan

    2015-01-01

    Using a combination of low-pressure oxygen and high temperatures, isotropic and anisotropic silicon (Si) etch rates can be controlled up to ten micron per minute. By varying the process conditions, we show that the vertical-to-lateral etch rate ratio can be controlled from 1:1 isotropic etch to 1.8:1 anisotropic. This simple Si etching technique combines the main respective advantages of both wet and dry Si etching techniques such as fast Si etch rate, stiction-free, and high etch rate uniformity across a wafer. In addition, this alternative O2-based Si etching technique has additional advantages not commonly associated with dry etchants such as avoiding the use of halogens and has no toxic by-products, which improves safety and simplifies waste disposal. Furthermore, this process also exhibits very high selectivity (>1000:1) with conventional hard masks such as silicon carbide, silicon dioxide and silicon nitride, enabling deep Si etching. In these initial studies, etch rates as high as 9.2 μm/min could be achieved at 1150 °C. Empirical estimation for the calculation of the etch rate as a function of the feature size and oxygen flow rate are presented and used as proof of concepts. PMID:26634813

  9. Overview of atomic layer etching in the semiconductor industry

    SciTech Connect

    Kanarik, Keren J. Lill, Thorsten; Hudson, Eric A.; Sriraman, Saravanapriyan; Tan, Samantha; Marks, Jeffrey; Vahedi, Vahid; Gottscho, Richard A.

    2015-03-15

    Atomic layer etching (ALE) is a technique for removing thin layers of material using sequential reaction steps that are self-limiting. ALE has been studied in the laboratory for more than 25 years. Today, it is being driven by the semiconductor industry as an alternative to continuous etching and is viewed as an essential counterpart to atomic layer deposition. As we enter the era of atomic-scale dimensions, there is need to unify the ALE field through increased effectiveness of collaboration between academia and industry, and to help enable the transition from lab to fab. With this in mind, this article provides defining criteria for ALE, along with clarification of some of the terminology and assumptions of this field. To increase understanding of the process, the mechanistic understanding is described for the silicon ALE case study, including the advantages of plasma-assisted processing. A historical overview spanning more than 25 years is provided for silicon, as well as ALE studies on oxides, III–V compounds, and other materials. Together, these processes encompass a variety of implementations, all following the same ALE principles. While the focus is on directional etching, isotropic ALE is also included. As part of this review, the authors also address the role of power pulsing as a predecessor to ALE and examine the outlook of ALE in the manufacturing of advanced semiconductor devices.

  10. Synergistic etch rates during low-energetic plasma etching of hydrogenated amorphous carbon

    SciTech Connect

    Hansen, T. A. R.; Weber, J. W.; Colsters, P. G. J.; Mestrom, D. M. H. G.; Sanden, M. C. M. van de; Engeln, R.

    2012-07-01

    The etch mechanisms of hydrogenated amorphous carbon thin films in low-energetic (<2 eV) high flux plasmas are investigated with spectroscopic ellipsometry. The results indicate a synergistic effect for the etch rate between argon ions and atomic hydrogen, even at these extremely low kinetic energies. Ion-assisted chemical sputtering is the primary etch mechanism in both Ar/H{sub 2} and pure H{sub 2} plasmas, although a contribution of swift chemical sputtering to the total etch rate is not excluded. Furthermore, ions determine to a large extent the surface morphology during plasma etching. A high influx of ions enhances the etch rate and limits the surface roughness, whereas a low ion flux promotes graphitization and leads to a large surface roughness (up to 60 nm).

  11. Symphony and cacophony in ion track etching: how to control etching results

    NASA Astrophysics Data System (ADS)

    Fink, D.; Kiv, A.; Cruz, S. A.; Muñoz H., G.; Vacík, J.

    2012-07-01

    In general, etching of two identical ion-irradiated polymer foils in the same vessel with the same etchant for the same times does not lead to identical track shapes in both foils. In contrast, the track shapes, the etching speeds, and consequently also the etchant consumption of the two foils diverge increasingly with increasing etching times, unless this is prevented by forceful external equilibration of the system. This tendency toward divergence of a system of multiple ion tracks originates from its lack of self-synchronization during etching. A theory has been developed for this case that also shows general applicability to other diverging effects in human life.

  12. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  13. Plasma etching: Yesterday, today, and tomorrow

    SciTech Connect

    Donnelly, Vincent M.; Kornblit, Avinoam

    2013-09-15

    The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

  14. Electron beam directed etching of hexagonal boron nitride.

    PubMed

    Elbadawi, Christopher; Tran, Trong Toan; Kolíbal, Miroslav; Šikola, Tomáš; Scott, John; Cai, Qiran; Li, Lu Hua; Taniguchi, Takashi; Watanabe, Kenji; Toth, Milos; Aharonovich, Igor; Lobo, Charlene

    2016-09-28

    Hexagonal boron nitride (hBN) is a wide bandgap van der Waals material with unique optical properties that make it attractive for two dimensional (2D) photonic and optoelectronic devices. However, broad deployment and exploitation of hBN is limited by alack of suitable material and device processing and nano prototyping techniques. Here we present a high resolution, single step electron beam technique for chemical dry etching of hBN. Etching is achieved using H2O as a precursor gas, at both room temperature and elevated hBN temperatures. The technique enables damage-free, nano scale, iterative patterning of supported and suspended 2D hBN, thus opening the door to facile fabrication of hBN-based 2D heterostructures and devices. PMID:27603125

  15. Reduction of Aspect Ratio Dependency in Silicon Trench Etch

    NASA Astrophysics Data System (ADS)

    Bates, Robert

    2013-09-01

    The etch rate of deep features in silicon, such as trenches and vias, can vary significantly with the changing aspect ratio (AR) of the feature. This work focused on using a continuous plasma process utilizing a gas mixture of SF6-C4F8-Ar to produce trenches of varying widths and depths. Optical and electrical diagnostics of percent flow, total flow and RF bias on trench profiles were investigated. Experiments were also performed to show that the etch rate of low AR features can be reduced through the deposition of a passivation layer and thereby allow larger AR features to ``catch up''. It is also possible to invert the ARDE in certain circumstances. Financial Support: TI/SRC Award # 2261.001.

  16. Investigation of Nitride Morphology After Self-Aligned Contact Etch

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Keil, J.; Helmer, B. A.; Chien, T.; Gopaladasu, P.; Kim, J.; Shon, J.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Self-Aligned Contact (SAC) etch has emerged as a key enabling technology for the fabrication of very large-scale memory devices. However, this is also a very challenging technology to implement from an etch viewpoint. The issues that arise range from poor oxide etch selectivity to nitride to problems with post etch nitride surface morphology. Unfortunately, the mechanisms that drive nitride loss and surface behavior remain poorly understood. Using a simple langmuir site balance model, SAC nitride etch simulations have been performed and compared to actual etched results. This approach permits the study of various etch mechanisms that may play a role in determining nitride loss and surface morphology. Particle trajectories and fluxes are computed using Monte-Carlo techniques and initial data obtained from double Langmuir probe measurements. Etched surface advancement is implemented using a shock tracking algorithm. Sticking coefficients and etch yields are adjusted to obtain the best agreement between actual etched results and simulated profiles.

  17. Nonhomogeneous surface properties of parylene-C film etched by an atmospheric pressure He/O2 micro-plasma jet in ambient air

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Yang, Bin; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng; Liu, Jingquan

    2016-10-01

    Surface properties of parylene-C film etched by an atmospheric pressure He/O2 micro-plasma jet in ambient air were investigated. The morphologies and chemical compositions of the etched surface were analyzed by optical microscopy, SEM, EDS, XPS and ATR-FTIR. The microscopy and SEM images showed the etched surface was nonhomogeneous with six discernable ring patterns from the center to the outside domain, which were composed of (I) a central region; (II) an effective etching region, where almost all of the parylene-C film was removed by the plasma jet with only a little residual parylene-C being functionalized with carboxyl groups (Cdbnd O, Osbnd Cdbnd O-); (III) an inner etching boundary; (IV) a middle etching region, where the film surface was smooth and partially removed; (V) an outer etching boundary, where the surface was decorated with clusters of debris, and (VI) a pristine parylene-C film region. The analysis of the different morphologies and chemical compositions illustrated the different localized etching process in the distinct regions. Besides, the influence of O2 flow rate on the surface properties of the etched parylene-C film was also investigated. Higher volume of O2 tended to weaken the nonhomogeneous characteristics of the etched surface and improve the etched surface quality.

  18. Comparative study of GaN mesa etch characteristics in Cl{sub 2} based inductively coupled plasma with Ar and BCl{sub 3} as additive gases

    SciTech Connect

    Rawal, Dipendra Singh Arora, Henika; Sehgal, Bhupender Kumar; Muralidharan, Rangarajan

    2014-05-15

    GaN thin film etching is investigated and compared for mesa formation in inductively coupled plasma (ICP) of Cl{sub 2} with Ar and BCl{sub 3} gas additives using photoresist mask. Etch characteristics are studied as a function of ICP process parameters, viz., ICP power, radio frequency (RF) power, and chamber pressure at fixed total flow rate. The etch rate at each ICP/RF power is 0.1–0.2 μm/min higher for Cl{sub 2}/Ar mixture mainly due to higher Cl dissociation efficiency of Ar additive that readily provides Cl ion/radical for reaction in comparison to Cl{sub 2}/BCl{sub 3} mixture. Cl{sub 2}/Ar mixture also leads to better photoresist mask selectivity. The etch-induced roughness is investigated using atomic force microscopy. Cl{sub 2}/Ar etching has resulted in lower root-mean-square roughness of GaN etched surface in comparison to Cl{sub 2}/BCl{sub 3} etching due to increased Ar ion energy and flux with ICP/RF power that enhances the sputter removal of etch product. The GaN surface damage after etching is also evaluated using room temperature photoluminescence and found to be increasing with ICP/RF power for both the etch chemistries with higher degree of damage in Cl{sub 2}/BCl{sub 3} etching under same condition.

  19. Surface engineering on CeO₂ nanorods by chemical redox etching and their enhanced catalytic activity for CO oxidation.

    PubMed

    Gao, Wei; Zhang, Zhiyun; Li, Jing; Ma, Yuanyuan; Qu, Yongquan

    2015-07-21

    Controllable surface properties of nanocerias are desired for various catalytic processes. There is a lack of efficient approaches to adjust the surface properties of ceria to date. Herein, a redox chemical etching method was developed to controllably engineer the surface properties of ceria nanorods. Ascorbic acid and hydrogen peroxide were used to perform the redox chemical etching process, resulting in a rough surface and/or pores on the surface of ceria nanorods. Increasing the etching cycles induced a steady increase of the specific surface area, oxygen vacancies and surface Ce(3+) fractions. As a result, the etched nanorods delivered enhanced catalytic activity for CO oxidation, compared to the non-etched ceria nanorods. Our method provides a novel and facile approach to continuously adjust the surface properties of ceria for practical applications.

  20. Fine-tuning the etch depth profile via dynamic shielding of ion beam

    NASA Astrophysics Data System (ADS)

    Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

    2016-08-01

    We introduce a method for finely adjusting the etch depth profile by dynamic shielding in the course of ion beam etching (IBE), which is crucial for the ultra-precision fabrication of large optics. We study the physical process of dynamic shielding and propose a parametric modeling method to quantitatively analyze the shielding effect on etch depths, or rather the shielding rate, where a piecewise Gaussian model is adopted to fit the shielding rate profile. Two experiments were conducted. The experimental result of parametric modeling of shielding rate profiles shows that the shielding rate profile is significantly influenced by the rotary angle of the leaf. The result of the experiment on fine-tuning the etch depth profile shows good agreement with the simulated result, which preliminarily verifies the feasibility of our method.

  1. Low-loss, submicron chalcogenide integrated photonics with chlorine plasma etching

    SciTech Connect

    Chiles, Jeff; Malinowski, Marcin; Rao, Ashutosh; Novak, Spencer; Richardson, Kathleen; Fathpour, Sasan

    2015-03-16

    A chlorine plasma etching-based method for the fabrication of high-performance chalcogenide-based integrated photonics on silicon substrates is presented. By optimizing the etching conditions, chlorine plasma is employed to produce extremely low-roughness etched sidewalls on waveguides with minimal penalty to propagation loss. Using this fabrication method, microring resonators with record-high intrinsic Q-factors as high as 450 000 and a corresponding propagation loss as low as 0.42 dB/cm are demonstrated in submicron chalcogenide waveguides. Furthermore, the developed chlorine plasma etching process is utilized to demonstrate fiber-to-waveguide grating couplers in chalcogenide photonics with high power coupling efficiency of 37% for transverse-electric polarized modes.

  2. Strongly reduced Si surface recombination by charge injection during etching in diluted HF/HNO3.

    PubMed

    Greil, Stefanie M; Schöpke, Andreas; Rappich, Jörg

    2012-08-27

    Herein, we investigate the behaviour of the surface recombination of light-induced charge carriers during the etching of Si in alkaline (KOH) and acidic etching solutions of HF/HNO(3)/CH(3)COOH (HNA) or HF/HNO(3)/H(3)PO(4) (HNP) at different concentration ratios of HF and HNO(3) by means of photoluminescence (PL) measurements. The surface recombination velocity is strongly reduced during the first stages of etching in HF/HNO(3)-containing solutions pointing to a interface well passivated by the etching process, where a positive surface charge is induced by hole injection from NO-related surface species into the Si near-surface region (back surface field effect). This injected charge leads to a change in band bending by about 150 mV that repulses the light-induced charge carriers from the surface and therefore enhances the photoluminescence intensity, since non-radiative surface recombination is reduced.

  3. Method for providing an arbitrary three-dimensional microstructure in silicon using an anisotropic deep etch

    DOEpatents

    Morales, Alfredo M.; Gonzales, Marcela

    2004-06-15

    The present invention describes a method for fabricating an embossing tool or an x-ray mask tool, providing microstructures that smoothly vary in height from point-to-point in etched substrates, i.e., structure which can vary in all three dimensions. The process uses a lithographic technique to transfer an image pattern in the surface of a silicon wafer by exposing and developing the resist and then etching the silicon substrate. Importantly, the photoresist is variably exposed so that when developed some of the resist layer remains. The remaining undeveloped resist acts as an etchant barrier to the reactive plasma used to etch the silicon substrate and therefore provides the ability etch structures of variable depths.

  4. A New Dry Etching Method with the High Etching Rate for Patterning Cross-Linked SU-8 Thick Films

    NASA Astrophysics Data System (ADS)

    Han, Jingning; Yin, Zhifu; Zou, Helin; Wang, Wenqiang; Feng, Jianbo

    2016-05-01

    Photo sensitive polymer SU-8, owing to its excellent mechanical properties and dielectric properties on polymerization, is widely used in MEMS device fabrications. However, the removing, stripping or re-patterning of the cross-linked SU-8 is a difficult issue. In this paper, CF4/O2 gas mixture provided by a plasma asher equipment was used for the patterning of cross-linked SU-8 material. The RF power, the temperature of the substrate holder, chamber pressure and gas concentration were optimized for the cross-linked SU-8 etching process. When the CF4/O2 mixture contains about 5%CF4 by volume, the etching rate can be reached at 5.2 μm/min.

  5. Effect of Cl{sub 2}- and HBr-based inductively coupled plasma etching on InP surface composition analyzed using in situ x-ray photoelectron spectroscopy

    SciTech Connect

    Bouchoule, S.; Vallier, L.; Patriarche, G.; Chevolleau, T.; Cardinaud, C.

    2012-05-15

    A Cl{sub 2}-HBr-O{sub 2}/Ar inductively coupled plasma (ICP) etching process has been adapted for the processing of InP-based heterostructures in a 300-mm diameter CMOS etching tool. Smooth and anisotropic InP etching is obtained at moderate etch rate ({approx}600 nm/min). Ex situ x-ray energy dispersive analysis of the etched sidewalls shows that the etching anisotropy is obtained through a SiO{sub x} passivation mechanism. The stoichiometry of the etched surface is analyzed in situ using angle-resolved x-ray photoelectron spectroscopy. It is observed that Cl{sub 2}-based ICP etching results in a significantly P-rich surface. The phosphorous layer identified on the top surface is estimated to be {approx}1-1.3-nm thick. On the other hand InP etching in HBr/Ar plasma results in a more stoichiometric surface. In contrast to the etched sidewalls, the etched surface is free from oxides with negligible traces of silicon. Exposure to ambient air of the samples submitted to Cl{sub 2}-based chemistry results in the complete oxidation of the P-rich top layer. It is concluded that a post-etch treatment or a pure HBr plasma step may be necessary after Cl{sub 2}-based ICP etching for the recovery of the InP material.

  6. Pattern inspection of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2015-07-01

    Patterned mask inspection for an etched multilayer (ML) EUV mask was investigated. In order to optimize the mask structure from the standpoint of not only a pattern inspection by using a projection electron microscope (PEM), but also by considering the other fabrication processes using electron beam (EB) techniques such as CD metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients (SEECs) of the candidate materials for conductive layer, we evaluated the image contrast and the influence of charging effect. In the cases of 40-pair-ML, 16 nm sized extrusion and intrusion defects were found to be detectable more than 10 sigma in hp 44 nm, 40 nm, and 32 nm line and space (L/S) patterns. Reducing 40-pair-ML to 20-pair-ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16 nm sized defects remained detectable. A double layer structure with 2.5-nm-thik B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  7. The effect of HF etching on the surface quality and figure of fused silica optics

    NASA Astrophysics Data System (ADS)

    Xu, Jiafeng; Xu, Xueke; Wei, Chaoyang; Gao, Wenlan; Yang, Minghong; Shao, Jianda; Liu, Shijie

    2015-08-01

    The effect of deep HF etching on the surface quality and figure of fused silica optics has been investigated systematically. Fused silica samples (100 mm in diameter x 10 mm thick) were manufactured using the conventional grinding and polishing process. These processed samples are etched with different removal depth. Initially, the surface quality of fused silica samples is characterized in terms of surface roughness and surface defects. Many digs not more than 1μm deep are emerged which originates from the micron grinding cracks and crack pits. These digs worsened the surface roughness and frosted the sample. While submillimeter subsurface damage exposed through etching appear as sparkling dots under the high power lamp. The average total length of millimeter scratches on single surfaces is over 200 mm. Not all millimeter scratches could be exposed until removal depth of up to 2 μm. Finally, the surface figure behavior during deep etching has also been figured out. Etching on the edge of the upper surface of samples placed horizontally went faster than on the inside parts. The surface of samples placed vertically assumed a more complicated removal distribution, which can be both explained in terms of "fringe tip effect". For the change of surface figure PV, the initial surface figure feature plays an important role as well as the etching removal distribution.

  8. Dry etching techniques for active devices based on hexagonal boron nitride epilayers

    SciTech Connect

    Grenadier, Samuel; Li, Jing; Lin, Jingyu; Jiang, Hongxing

    2013-11-15

    Hexagonal boron nitride (hBN) has emerged as a fundamentally and technologically important material system owing to its unique physical properties including layered structure, wide energy bandgap, large optical absorption, and neutron capture cross section. As for any materials under development, it is necessary to establish device processing techniques to realize active devices based on hBN. The authors report on the advancements in dry etching techniques for active devices based on hBN epilayers via inductively coupled plasma (ICP). The effect of ICP radio frequency (RF) power on the etch rate and vertical side wall profile was studied. The etching depth and angle with respect to the surface were measured using atomic force microscopy showing that an etching rate ∼1.25 μm/min and etching angles >80° were obtained. Profilometer data and scanning electron microscope images confirmed these results. This work demonstrates that SF{sub 6} is very suitable for etching hBN epilayers in RF plasma environments and can serve as a guide for future hBN device processing.

  9. Dry etch fabrication of ultra-thin porous silicon membranes

    NASA Astrophysics Data System (ADS)

    Hajj-Hassan, Mohamad; Cheung, Maurice; Chodavarapu, Vamsy

    2010-06-01

    Porous silicon is a well-known material with interesting properties for a wide variety of applications in electronics, photonics, medicine, and informatics. We demonstrate fabrication of porous silicon using a dry etching technique. We demonstrate free standing porous silicon membranes that are only few microns thick. Free standing porous silicon membranes have the ability to behave as a size-selective permeable membrane by allowing specific sized molecules to pass through while retaining others. Here, we employ the XeF2 to develop few micrometers thick suspended porous silicon membranes. The flexibility of XeF2 etching process allows the production of mechanically stable membranes of different thicknesses. By choosing the appropriate etching parameters and conditions, pore size can be tuned to produce porous silicon with optically attractive features and desired optical behaviors. The pore size, porosity and thickness of the various developed ultra-thin free-standing porous silicon membranes were characterized with scanning electron microscopy and optical transmittance measurements. The fabricated free-standing porous membrane has a typical transmission spectrum of regular silicon modulated by Fabry-Perot fringes. Porous silicon thin membranes that combine the properties of a mechanically and chemically stable high surface area matrix with the function of an optical transducer may find many used in biomedical microdevices.

  10. Three-dimensional nanostructures by direct laser etching of Si

    NASA Astrophysics Data System (ADS)

    Müllenborn, M.; Dirac, H.; Petersen, J. W.

    1995-02-01

    Nanostructures have been machined into Si by a high-resolution laser direct write system. The Si substrate is locally heated above its melting point by a continuous-wave laser and rapidly etched by dry Cl 2 gas. If the solid-to-liquid transition is adjusted to occur only at the peak of the temperature profile, the melt size is significantly smaller than the diffraction-limited spot size. This can translate to extremely small etched features because of the high selectivity of the etching process for liquid Si compared to crystalline Si. By using objectives with a high numerical aperture, 488 nm as well as 351 nm light from an Ar ion laser, and X/Y/Z translation stages for moving the substrate instead of steering the beam, we have achieved line widths below 200 nm combined with very high scanning accuracy and speed. The resolution limit for Si machining is determined by the selectivity of the chemical reaction rather than the laser spot size. Interfacing to computer-aided design (CAD) software allows us to remove layer by layer of a truly three-dimensional nanostructure.

  11. Pattern inspection of etched multilayer extreme ultraviolet mask

    NASA Astrophysics Data System (ADS)

    Iida, Susumu; Hirano, Ryoichi; Amano, Tsuyoshi; Watanabe, Hidehiro

    2016-04-01

    Patterned mask inspection for an etched multilayer (ML) extreme ultraviolet mask was investigated. In order to optimize the mask structure from the standpoint of a pattern inspection the mask structure not only from the standpoint of a pattern inspection by using a projection electron microscope but also by using a projection electron microscope but also by considering the other fabrication processes using electron beam techniques such as critical dimension metrology and mask repair, we employed a conductive layer between the ML and substrate. By measuring the secondary electron emission coefficients of the candidate materials for the conductive layer, we evaluated the image contrast and the influence of the charging effect. In the cases of 40-pair ML, 16-nm-sized extrusion and intrusion defects were found to be detectable more than 10 sigma in half pitch 44, 40, and 32 nm line-and-space patterns. Reducing 40-pair ML to 20-pair ML degraded the image contrast and the defect detectability. However, by selecting B4C as a conductive layer, 16-nm-sized defects and etching residues remained detectable. The 16-nm-sized defects were also detected after the etched part was refilled with Si. A double-layer structure with 2.5-nm-thick B4C on metal film used as a conductive layer was found to have sufficient conductivity and also was found to be free from the surface charging effect and influence of native oxide.

  12. Polymer etching in the oxygen afterglow - Increased etch rates with increased reactor loading

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1989-01-01

    Reactor loading has an effect on the etch rate (rate of decrease of film thickness) of films of polyvinylfluoride (Tedlar) and polyethylene exposed in the afterglow of an RF discharge in oxygen. The etch rate is found to increase with the total surface area of the polymer exposed in the reactor. The etch rates of polypyromellitimide (Kapton H) and polystyrene under these conditions are very low. However, the etch rate of these polymers is greatly enhanced by adding either Tedlar or polyethylene to the reactor. A kinetic model is proposed based on the premise that the oxygen atoms produced by the RF discharge react with Tedlar or polyethylene to produce a much more reactive species, which dominates the etching of the polymers studied.

  13. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    SciTech Connect

    Nakazaki, Nobuya Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  14. Photoluminescence of porous silicon stain etched and doped with erbium and ytterbium

    NASA Astrophysics Data System (ADS)

    Díaz-Herrera, B.; González-Díaz, B.; Guerrero-Lemus, R.; Hernández-Rodríguez, C.; Méndez-Ramos, J.; Rodríguez, V. D.

    2009-02-01

    A novel low cost process has been developed for application in porous silicon-based photodetectors and solar cells, where conventional doping processes are not affordable because of the high processing cost and technical difficulties. Ytterbium and erbium (Yb 3+-Er 3+) ions were introduced into luminescent porous silicon stain etched by thermal diffusion. Doping profiles were evaluated by energy-dispersive spectroscopy analysis. The visible and near-infrared photoluminescence of Yb 3+-Er 3+ co-doped stain-etched porous silicon layers is observed and evaluated under 980 nm pumping. Up-conversion processes that could improve the efficiency of silicon-based solar cells are detected.

  15. Patterning enhancement techniques by reactive ion etch

    NASA Astrophysics Data System (ADS)

    Honda, Masanobu; Yatsuda, Koichi

    2012-03-01

    The root causes of issues in state-of-the-arts resist mask are low plasma tolerance in etch and resolution limit in lithography. This paper introduces patterning enhancement techniques (PETs) by reactive ion etch (RIE) that solve the above root causes. Plasma tolerance of resist is determined by the chemical structure of resin. We investigated a hybrid direct current (DC) / radio frequency (RF) RIE to enhance the plasma tolerance with several gas chemistries. The DC/RF hybrid RIE is a capacitive coupled plasma etcher with a superimposed DC voltage, which generates a ballistic electron beam. We clarified the mechanism of resist modification, which resulted in higher plasma tolerance[1]. By applying an appropriate gas to DC superimposed (DCS) plasma, etch resistance and line width roughness (LWR) of resist were improved. On the other hand, RIE can patch resist mask. RIE does not only etch but also deposits polymer onto the sidewall with sedimentary type gases. In order to put the deposition technique by RIE in practical use, it is very important to select an appropriate gas chemistry, which can shrink CD and etch BARC. By applying this new technique, we successfully fabricated a 35-nm hole pattern with a minimum CD variation.

  16. Plasma etching a ceramic composite. [evaluating microstructure

    NASA Technical Reports Server (NTRS)

    Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

    1992-01-01

    Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

  17. Anisotropic etching of monocrystalline silicon under subcritical conditions

    NASA Astrophysics Data System (ADS)

    Gonzalez-Pereyra, Nestor Gabriel

    Sub- and supercritical fluids remain an underexploited resource for materials processing. Around its critical point a common compound such as water behaves like a different substance exhibiting changes in its properties that modify its behavior as a solvent and unlock reaction paths not viable in other conditions. In the subcritical region water's properties can be directed by controlling temperature and pressure. Water and silicon are two of the most abundant, versatile, environmentally non-harmful, and simplest substances on Earth. They are among the most researched and best-known substances. Both are ubiquitous and essential for present-day world. Silicon is fundamental in semiconductor fabrication, microelectromechanical systems, and photovoltaic cells. Wet etching of silicon is a fabrication strategy shared by these three applications. Processing of silicon requires large amounts of water, often involving dangerous and environmentally hazardous chemicals. Yet, minimal knowledge is available on the ways high temperature water interacts with crystalline silicon. The purpose of this project is to identify and implement a method for the modification of monocrystalline silicon surfaces with three important characteristics: 1) requires minimal amounts of added chemicals, 2) controllability of morphological features formed, 3) reduced processing time. This will be accomplished by subjecting crystalline silicon to diluted alkaline solutions working in the subcritical region of water. This approach allows for variations on surface morphologies and etching rates by adapting the reactions conditions, with focus on composition and temperature of the solutions used. The work reported discusses the techniques used for producing surfaces with a variety of morphologies that ultimately allowed to create patterns and textures on silicon wafers, using highly diluted alkaline solutions that can be used for photovoltaic applications. These morphologies were created with a

  18. Magnetic field sensor using the fiber loop ring-down technique and an etched fiber coated with magnetic fluid.

    PubMed

    Shen, Tao; Feng, Yue; Sun, Binchao; Wei, Xinlao

    2016-02-01

    The fiber loop ring-down spectroscopy technique is introduced into the evanescent-field-based sensing scheme in order to create a new type of fiber-based magnetic field sensor. As a consequence, the sensitivity and stability of the magnetic field sensing system are significantly enhanced. The sensor head is constructed using a section of a single-mode fiber with its cladding partially etched. The process of fiber etching is described in detail, and the relationship between the diameter of the etched fiber and the etching time is experimentally investigated. After adopting the appropriate size of the etched fiber, the final experimental results show that the magnetic field strength has a well-defined linear relationship with the inverse of the ring-down time τ over a range of 30 mT with a sensitivity of 95.5 ns/mT.

  19. Magnetic field sensor using the fiber loop ring-down technique and an etched fiber coated with magnetic fluid.

    PubMed

    Shen, Tao; Feng, Yue; Sun, Binchao; Wei, Xinlao

    2016-02-01

    The fiber loop ring-down spectroscopy technique is introduced into the evanescent-field-based sensing scheme in order to create a new type of fiber-based magnetic field sensor. As a consequence, the sensitivity and stability of the magnetic field sensing system are significantly enhanced. The sensor head is constructed using a section of a single-mode fiber with its cladding partially etched. The process of fiber etching is described in detail, and the relationship between the diameter of the etched fiber and the etching time is experimentally investigated. After adopting the appropriate size of the etched fiber, the final experimental results show that the magnetic field strength has a well-defined linear relationship with the inverse of the ring-down time τ over a range of 30 mT with a sensitivity of 95.5 ns/mT. PMID:26836067

  20. Fabrication of volcano-shaped nano-patterned sapphire substrates using colloidal self-assembly and wet chemical etching.

    PubMed

    Geng, Chong; Zheng, Lu; Fang, Huajing; Yan, Qingfeng; Wei, Tongbo; Hao, Zhibiao; Wang, Xiaoqing; Shen, Dezhong

    2013-08-23

    Patterned sapphire substrates (PSS) have been widely used to enhance the light output power in GaN-based light emitting diodes. The shape and feature size of the pattern in a PSS affect its enhancement efficiency to a great degree. In this work we demonstrate the nanoscale fabrication of volcano-shaped PSS using a wet chemical etching approach in combination with a colloidal monolayer templating strategy. Detailed analysis by scanning electron microscopy reveals that the unique pattern shape is a result of the different corrosion-resistant abilities of silica masks of different effective heights during wet chemical etching. The formation of silica etching masks of different effective heights has been ascribed to the silica precursor solution in the interstice of the colloidal monolayer template being distributed unevenly after infiltration. In the subsequent wet chemical etching process, the active reaction sites altered as etching duration was prolonged, resulting in the formation of volcano-shaped nano-patterned sapphire substrates.

  1. Fabrication and photocatalytic properties of silicon nanowires by metal-assisted chemical etching: effect of H2O2 concentration

    PubMed Central

    2012-01-01

    In the current study, monocrystalline silicon nanowire arrays (SiNWs) were prepared through a metal-assisted chemical etching method of silicon wafers in an etching solution composed of HF and H2O2. Photoelectric properties of the monocrystalline SiNWs are improved greatly with the formation of the nanostructure on the silicon wafers. By controlling the hydrogen peroxide concentration in the etching solution, SiNWs with different morphologies and surface characteristics are obtained. A reasonable mechanism of the etching process was proposed. Photocatalytic experiment shows that SiNWs prepared by 20% H2O2 etching solution exhibit the best activity in the decomposition of the target organic pollutant, Rhodamine B (RhB), under Xe arc lamp irradiation for its appropriate Si nanowire density with the effect of Si content and contact area of photocatalyst and RhB optimized. PMID:23217211

  2. Dry etching of beta-SiC in CF4 and CF4 + O2 mixtures

    NASA Technical Reports Server (NTRS)

    Palmour, J. W.; Davis, R. F.; Wallett, T. M.; Bhasin, K. B.

    1986-01-01

    Dry etching of cubic (100) beta-SiC single-crystal thin films produced via chemical-vapor deposition (CVD) has been performed in CF4 and CF4 + O2 mixtures, in both the reactive-ion-etching (RIE) and plasma-etching modes. The latter process yielded measurable etch rates, but produced a dark surface layer which appears, from the results of secondary-ion mass spectrometry, to be residual SiC. The RIE samples had no residual layer, but Auger electron spectroscopy did reveal a C-rich surface. The optimal RIE conditions were obtained with 10 sccm of pure CF4 at 40 mtorr and a power density of 0.548 W/sq cm, giving an etch rate of 23.3 nm/min. Neither the increase of temperature between 293 and 573 K, nor the incremental addition of O2 to CF4 to 50 percent, produced any strong effect on the etch rates of SiC during RIE. Pictorial evidence of fine line structures produced by RIE of beta-SiC films are also presented.

  3. Enamel resistance to demineralization following Er:YAG laser etching for bonding orthodontic brackets

    PubMed Central

    Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

    2012-01-01

    Background: Several studies have shown that laser-etching of enamel for bonding orthodontic brackets could be an appropriate alternative for acid conditioning, since a potential advantage of laser could or might be caries prevention. This study compared enamel resistance to demineralization following etching with acid phosphoric or Er:YAG laser for bonding orthodontic brackets. Materials and Methods: Fifty sound human premolars were divided into two equal groups. In the first group, enamel was etched with 37% phosphoric acid for 15 seconds. In the second group, Er:YAG laser (wavelength, 2 940 nm; 300 mJ/pulse, 10 pulses per second, 10 seconds) was used for tooth conditioning. The teeth were subjected to 4-day PH-cycling process to induce caries-like lesions. The teeth were then sectioned and the surface area of the lesion was calculated in each microphotographs and expressed in pixel. The total surface of each specimen was 196 608 pixels. Results: Mean lesion areas were 7 171 and 7532 pixels for Laser-etched and Acid-etched groups, respectively. The two sample t-test showed that there was no significant difference in lesion area between the two groups (P = 0.914). Conclusion: Although Er:YAG laser seems promising for etching enamel before bonding orthodontic brackets, it does not reduce enamel demineralization when exposed to acid challenge. PMID:23162591

  4. Clinical Evaluation of Etched Enamel Discoloration following Immediate and Delayed Exposure to Colored Agents

    PubMed Central

    Basafa, Mohammad; Jahanbin, Arezoo; Borouzi Niat, Alireza; Basafa, Soroush; Banihashemi, Elham

    2014-01-01

    Introduction. The aim was to evaluate etched enamel discoloration following immediate and delayed exposure to colored agents. Method & Material. 64 premolars were divided into four groups. Buccal surface of the teeth was divided into two halves and baseline color values were measured. One half was covered and the other half was etched and dried. In first and second groups, the patients did not eat any colored agents for the next 24 hours. Both halves were colorimetered after 48 hours and 1 month, respectively. In third and fourth groups, the process was similar, but the patients drank cola and avoid eating any other colored agents and the teeth were colorimetered after 48 hours and 1 month, respectively. Color change values (ΔE) of each half were calculated according to CIE lab system. Sign test was used to compare values of etched and unetched halves. P < 0.08 was set as significant. Results. A significant difference was observed in groups III and IV regarding comparison of ΔE of the etched and control enamel (P = 0.077). Conclusion. Exposure of etched enamel to colored agents in the first 24 hours after etching can affect its color which remains at least for one month. PMID:27379257

  5. Etching characteristics of chromium thin films by an electron beam induced surface reaction

    NASA Astrophysics Data System (ADS)

    Wang, Jianhua; Griffis, D. P.; Garcia, R.; Russell, P. E.

    2003-04-01

    In this paper, we demonstrate the etching of chromium (Cr) film on quartz through a surface reaction induced by an electron beam and enhanced with XeF2 gas. We have studied the influences of the electron beam energy, the gas flow rate and the specimen composition on the etch rate. The electron beam energy has significant influence on the etch rate. The etch rate made by an electron beam of 20 keV is five times higher compared to that made by a beam of 10 keV. The XeF2 gas flow rate shows little effect on the etch rate when the gas pressure is higher than 2 × 10-6 Torr. The structure and grain size of the Cr film did not show any apparent change under exposure to XeF2 or when irradiated by an electron beam, while the composition of Cr has a significant effect on the etch process. The material removal of Cr induced by an electron beam means that it can be applied to the direct fabrication of microstructures on Cr films and that it solves the contamination problem in Cr mask repair.

  6. Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

    SciTech Connect

    Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I.; Somorjai, G.A.

    2008-01-09

    A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TEM, and N{sub 2} adsorption measurements demonstrated that the structure of the nanoparticles and the mesoporous support remained conserved during etching in concentrated nitric acid. Both elemental analysis and ethylene hydrogenation indicated etching of Ag is only effective when [HNO{sub 3}] {ge} 7 M; below this concentration, the removal of Ag is only {approx}10%. Ethylene hydrogenation activity increased by four orders of magnitude after the etching of Pt octahedra that contained the highest fraction of silver. High-resolution transmission electron microscopy of the unsupported particles after etching demonstrated that etching does not alter the surface structure of the Pt nanoparticles. High [HNO{sub 3}] led to the decomposition of the capping agent, polyvinylpyrollidone (PVP); infrared spectroscopy confirmed that many decomposition products were present on the surface during etching, including carbon monoxide.

  7. SiC Homoepitaxy, Etching and Graphene Epitaxial Growth on SiC Substrates Using a Novel Fluorinated Si Precursor Gas (SiF4)

    NASA Astrophysics Data System (ADS)

    Rana, Tawhid; Chandrashekhar, M. V. S.; Daniels, Kevin; Sudarshan, Tangali

    2016-04-01

    Tetrafluorosilane (SiF4 or TFS), a novel precursor gas, has been demonstrated to perform three primary operations of silicon carbide-related processing: SiC etching, SiC epitaxial growth and graphene epitaxial growth. TFS etches SiC substrate vigorously in a H2 ambient by efficient Si removal from the surface, where SiC etch rate is a function of TFS gas concentration. In this SiC etching process, Si is removed by TFS and C is removed by H2. When propane is added to a H2 and TFS gas mixture, etching is halted and high-quality SiC epitaxy takes place in a Si droplet-free condition. TFS's ability to remove Si can also be exploited to grow epitaxial graphene in a controllable manner in an inert (Ar) ambient. Here, TFS enhances graphene growth by selective etching of Si from the SiC surface.

  8. Triple-phase boundary and power density enhancement in thin solid oxide fuel cells by controlled etching of the nickel anode.

    PubMed

    Ebrahim, Rabi; Yeleuov, Mukhtar; Issova, Ainur; Tokmoldin, Serekbol; Ignatiev, Alex

    2014-01-01

    Fabrication of microporous structures for the anode of a thin film solid oxide fuel cell (SOFC(s)) using controlled etching process has led us to increased power density and increased cell robustness. Micropores were etched in the nickel anode by both wet and electrochemical etching processes. The samples etched electrochemically showed incomplete etching of the nickel leaving linked nickel islands inside the pores. Samples which were wet- etched showed clean pores with no nickel island residues. Moreover, the sample with linked nickel islands in the anode pores showed higher output power density as compared to the sample with clean pores. This enhancement is related to the enlargement of the surface of contact between the fuel-anode-electrolyte (the triple-phase boundary).

  9. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    PubMed

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone. PMID:25629708

  10. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    PubMed

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  11. Pulsed Laser-Assisted Focused Electron-Beam-Induced Etching of Titanium with XeF 2 : Enhanced Reaction Rate and Precursor Transport

    DOE PAGES

    Noh, J. H.; Fowlkes, J. D.; Timilsina, R.; Stanford, M. G.; Lewis, B. B.; Rack, P. D.

    2015-01-28

    We introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing; we do this in order to enhance the etch rate of electron-beam-induced etching. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. Moreover, the evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. Finally, the increased etch rate is attributed to photothermally enhancedmore » Ti–F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.« less

  12. Pulsed Laser-Assisted Focused Electron-Beam-Induced Etching of Titanium with XeF 2 : Enhanced Reaction Rate and Precursor Transport

    SciTech Connect

    Noh, J. H.; Fowlkes, J. D.; Timilsina, R.; Stanford, M. G.; Lewis, B. B.; Rack, P. D.

    2015-01-28

    We introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing; we do this in order to enhance the etch rate of electron-beam-induced etching. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. Moreover, the evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. Finally, the increased etch rate is attributed to photothermally enhanced Ti–F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  13. Triple-phase boundary and power density enhancement in thin solid oxide fuel cells by controlled etching of the nickel anode

    PubMed Central

    2014-01-01

    Fabrication of microporous structures for the anode of a thin film solid oxide fuel cell (SOFC(s)) using controlled etching process has led us to increased power density and increased cell robustness. Micropores were etched in the nickel anode by both wet and electrochemical etching processes. The samples etched electrochemically showed incomplete etching of the nickel leaving linked nickel islands inside the pores. Samples which were wet- etched showed clean pores with no nickel island residues. Moreover, the sample with linked nickel islands in the anode pores showed higher output power density as compared to the sample with clean pores. This enhancement is related to the enlargement of the surface of contact between the fuel-anode-electrolyte (the triple-phase boundary). PMID:24982602

  14. Solderability enhancement of copper through chemical etching

    SciTech Connect

    Stevenson, J.O.; Guilinger, T.R.; Hosking, F.M.; Yost, F.G.; Sorensen, N.R.

    1995-05-01

    Sandia National Laboratories has established a Cooperative Research and Development Agreement with consortium members of the National Center for Manufacturing Sciences (NCMS) to develop fundamental generic technology in the area of printed wiring board materials and surface finishes. Improved solderability of copper substrates is an important component of the Sandia-NCMS program. The authors are investigating the effects of surface roughness on the wettability and solderability behavior of several different types of copper board finishes. In this paper, the authors present roughness and solderability characterizations for a variety of chemically-etched copper substrates. Initial testing on six chemical etches demonstrate that surface roughness can be greatly enhanced through chemical etching. Noticeable improvements in solder wettability were observed to accompany increases in roughness. A number of different algorithms and measures of roughness were used to gain insight into surface morphologies that lead to improved solderability.

  15. Oxide Etch Behavior in an Inductively Coupled C4F8 Discharge Characterized by Diode Laser Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Anderson, Harold; Barela, Marcus; Courtin, Geoff; Waters, Karla

    2001-10-01

    This study reports on oxide and photoresist etch characteristics in an inductively coupled GEC Reference Cell as a function of reactor source power, bias power and pressure using C4F8. Diode laser absorption spectroscopy (DLAS) has shown that C4F8 is largely dissociated to form C2F4, CF2 and CF in the discharge. Over an oxide surface, CF2 and CF are consumed in the oxide etch process, but only when the bias power is sufficient to keep the oxide surface clean through energetic ion bombardment. For C4F8, this transition occurs at 60 eV (75 W bias power) in the GEC Cell. At higher bias powers (125 W) where oxide etching is fast ( 600 nm/min.), CF2 appears to be the key radical for the etch process since 50 percent (2.7-3.0 mTorr in a 15 mTorr C4F8 discharge) is consumed. These values were obtained by comparing the CF2 concentrations over non-reactive wafer surfaces versus blanket oxide wafer surfaces undergoing etching. CF is shown to display a similar trend, but its concentration is an order of magnitude less than CF2, and consequently cannot account on a mass basis for the amount of reactants necessary to balance the amount of etch products. Over a PR surface, neither CF2 nor CF concentrations vary as a function of PR etch rate. Consequently, they do not appear to be involved in the PR etch mechanism. However, PR etching is also critically dependent on bias power. PR films etch presumably due to energetic ion bombardment that degrades the PR film, making it liable to attack by fluorine.

  16. Etching of fused silica fiber by metallic laser-induced backside wet etching technique

    NASA Astrophysics Data System (ADS)

    Vass, Cs.; Kiss, B.; Kopniczky, J.; Hopp, B.

    2013-08-01

    The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τFWHM = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm2, while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm2. The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

  17. Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF{sub 6} based plasmas

    SciTech Connect

    Perros, Alexander; Bosund, Markus; Sajavaara, Timo; Laitinen, Mikko; Sainiemi, Lauri; Huhtio, Teppo; Lipsanen, Harri

    2012-01-15

    The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 deg. C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF{sub 6} and O{sub 2} under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film's removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SF{sub x}{sup +} and O{sup +} chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF{sub 6} based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.

  18. SU-8 focus control mirrors released by XeF2 dry etch

    NASA Astrophysics Data System (ADS)

    Lukes, Sarah J.; Dickensheets, David L.

    2011-03-01

    SU8-2002 deformable membrane mirrors for primary focus control and compensation of focus-induced spherical aberration have been fabricated using a surface micromachining process with dry etching of silicon in XeF2. This process has a higher yield and realizes larger mirrors with a twofold improvement in stroke, relative to a wet release etch process previously described. The use of 3 mm x 4.24 mm elliptical mirrors for 45° incidence focus control in microscopy is described.

  19. The development of a method of producing etch resistant wax patterns on solar cells

    NASA Technical Reports Server (NTRS)

    Pastirik, E.

    1980-01-01

    A potentially attractive technique for wax masking of solar cells prior to etching processes was studied. This technique made use of a reuseable wax composition which was applied to the solar cell in patterned form by means of a letterpress printing method. After standard wet etching was performed, wax removal by means of hot water was investigated. Application of the letterpress wax printing process to silicon was met with a number of difficulties. The most serious shortcoming of the process was its inability to produce consistently well-defined printed patterns on the hard silicon cell surface.

  20. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    NASA Astrophysics Data System (ADS)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (<1° departure) and smooth (2.0 nm root mean square line-edge roughness (LER)) etch by chemically assisted Ar ion beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ˜60 nm min-1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  1. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    NASA Astrophysics Data System (ADS)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (<1° departure) and smooth (2.0 nm root mean square line-edge roughness (LER)) etch by chemically assisted Ar ion beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ∼60 nm min‑1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  2. The effect of hydrogen-based, high density plasma etching on the electronic properties of gallium nitride

    SciTech Connect

    Eddy, C.R. Jr.; Molnar, B.

    1996-11-01

    Development of devices based on the wide gap semiconductor gallium nitride (GaN) requires the realization of reliable, high fidelity, low damage pattern transfer processes. In this work, GaN thin films grown by OMVPE have been subjected to both chlorine- and methane/hydrogen-based etch chemistries in an electron cyclotron resonance microwave plasma reactive ion etching system. Both n-type and semi-insulating thin films have been utilized to examine the effect of these etch processes on the electronic properties of the materials. The methane/hydrogen-based etch system (CH{sub 4}/H{sub 2}/Ar) induced considerable changes in the electrical properties of both n-type and semi-insulating films, causing the former to become more insulating and the latter to become conducting. In both cases, the original electrical properties were recoverable after a short, high temperature anneal. In the chlorine-based etching system (Cl{sub 2}), no changes in the electrical properties were observed and etch rates five times greater than in the methane/hydrogen-based system were achieved. Proposed mechanism responsible for the observed behavior will be discussed. These results show that pattern transfer processes based in chlorine etch chemistries are more suitable for the generation of high performance GaN devices.

  3. Anisotropic etching of platinum electrodes at the onset of cathodic corrosion

    PubMed Central

    Hersbach, Thomas J. P.; Yanson, Alexei I.; Koper, Marc T. M.

    2016-01-01

    Cathodic corrosion is a process that etches metal electrodes under cathodic polarization. This process is presumed to occur through anionic metallic reaction intermediates, but the exact nature of these intermediates and the onset potential of their formation is unknown. Here we determine the onset potential of cathodic corrosion on platinum electrodes. Electrodes are characterized electrochemically before and after cathodic polarization in 10 M sodium hydroxide, revealing that changes in the electrode surface start at an electrode potential of −1.3 V versus the normal hydrogen electrode. The value of this onset potential rules out previous hypotheses regarding the nature of cathodic corrosion. Scanning electron microscopy shows the formation of well-defined etch pits with a specific orientation, which match the voltammetric data and indicate a remarkable anisotropy in the cathodic etching process, favouring the creation of (100) sites. Such anisotropy is hypothesized to be due to surface charge-induced adsorption of electrolyte cations. PMID:27554398

  4. Anisotropic etching of platinum electrodes at the onset of cathodic corrosion

    NASA Astrophysics Data System (ADS)

    Hersbach, Thomas J. P.; Yanson, Alexei I.; Koper, Marc T. M.

    2016-08-01

    Cathodic corrosion is a process that etches metal electrodes under cathodic polarization. This process is presumed to occur through anionic metallic reaction intermediates, but the exact nature of these intermediates and the onset potential of their formation is unknown. Here we determine the onset potential of cathodic corrosion on platinum electrodes. Electrodes are characterized electrochemically before and after cathodic polarization in 10 M sodium hydroxide, revealing that changes in the electrode surface start at an electrode potential of -1.3 V versus the normal hydrogen electrode. The value of this onset potential rules out previous hypotheses regarding the nature of cathodic corrosion. Scanning electron microscopy shows the formation of well-defined etch pits with a specific orientation, which match the voltammetric data and indicate a remarkable anisotropy in the cathodic etching process, favouring the creation of (100) sites. Such anisotropy is hypothesized to be due to surface charge-induced adsorption of electrolyte cations.

  5. Anisotropic etching of platinum electrodes at the onset of cathodic corrosion.

    PubMed

    Hersbach, Thomas J P; Yanson, Alexei I; Koper, Marc T M

    2016-01-01

    Cathodic corrosion is a process that etches metal electrodes under cathodic polarization. This process is presumed to occur through anionic metallic reaction intermediates, but the exact nature of these intermediates and the onset potential of their formation is unknown. Here we determine the onset potential of cathodic corrosion on platinum electrodes. Electrodes are characterized electrochemically before and after cathodic polarization in 10 M sodium hydroxide, revealing that changes in the electrode surface start at an electrode potential of -1.3 V versus the normal hydrogen electrode. The value of this onset potential rules out previous hypotheses regarding the nature of cathodic corrosion. Scanning electron microscopy shows the formation of well-defined etch pits with a specific orientation, which match the voltammetric data and indicate a remarkable anisotropy in the cathodic etching process, favouring the creation of (100) sites. Such anisotropy is hypothesized to be due to surface charge-induced adsorption of electrolyte cations. PMID:27554398

  6. Inductively coupled plasma-reactive ion etching of InSb using CH{sub 4}/H{sub 2}/Ar plasma

    SciTech Connect

    Zhang Guodong; Sun Weiguo; Xu Shuli; Zhao Hongyan; Su Hongyi; Wang Haizhen

    2009-07-15

    InSb is an important material for optoelectronic devices. Most InSb devices are currently wet etched, and the etching geometries are limited due to the isotropic nature of wet etching. Inductively coupled plasma (ICP)-reactive ion etching (RIE) is a more desirable alternative because it offers a means of producing small anisotropic structures especially needed in large format infrared focal plane arrays. This work describes the novel use of ICP-RIE for fabricating InSb mesas with CH{sub 4}/H{sub 2}/Ar plasma and presents the influences of the process parameters on the etch rate and surface morphology. The parameters investigated include bias radio frequency power (50-250 W), %CH{sub 4} in H{sub 2} (10-50), argon (Ar) partial pressure (0-0.3 Pa with total pressure of 1.0 Pa), and total pressure (0.35-4 Pa). With the process parameters optimized in this investigated ranges, good etching results have been achieved with etch rates up to 80 nm/min, and etch features with sidewall angles of about 80 degree sign , the etched surface is as smooth as before the RIE process.

  7. Selective emitter using a screen printed etch barrier in crystalline silicon solar cell.

    PubMed

    Song, Kyuwan; Kim, Bonggi; Lee, Hoongjoo; Lee, Youn-Jung; Park, Cheolmin; Balaji, Nagarajan; Ju, Minkyu; Choi, Jaewoo; Yi, Junsin

    2012-07-23

    The low level doping of a selective emitter by etch back is an easy and low cost process to obtain a better blue response from a solar cell. This work suggests that the contact resistance of the selective emitter can be controlled by wet etching with the commercial acid barrier paste that is commonly applied in screen printing. Wet etching conditions such as acid barrier curing time, etchant concentration, and etching time have been optimized for the process, which is controllable as well as fast. The acid barrier formed by screen printing was etched with HF and HNO3 (1:200) solution for 15 s, resulting in high sheet contact resistance of 90 Ω/sq. Doping concentrations of the electrode contact portion were 2 × 1021 cm-3 in the low sheet resistance (Rs) region and 7 × 1019 cm-3 in the high Rs region. Solar cells of 12.5 × 12.5 cm2 in dimensions with a wet etch back selective emitter Jsc of 37 mAcm-2, open circuit voltage (Voc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on Voc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with Jsc of 36.90 mAcm-2, Voc of 625.7 mV, and efficiency of 17.60%.

  8. Selective emitter using a screen printed etch barrier in crystalline silicon solar cell

    PubMed Central

    2012-01-01

    The low level doping of a selective emitter by etch back is an easy and low cost process to obtain a better blue response from a solar cell. This work suggests that the contact resistance of the selective emitter can be controlled by wet etching with the commercial acid barrier paste that is commonly applied in screen printing. Wet etching conditions such as acid barrier curing time, etchant concentration, and etching time have been optimized for the process, which is controllable as well as fast. The acid barrier formed by screen printing was etched with HF and HNO3 (1:200) solution for 15 s, resulting in high sheet contact resistance of 90 Ω/sq. Doping concentrations of the electrode contact portion were 2 × 1021 cm−3 in the low sheet resistance (Rs) region and 7 × 1019 cm−3 in the high Rs region. Solar cells of 12.5 × 12.5 cm2 in dimensions with a wet etch back selective emitter Jsc of 37 mAcm−2, open circuit voltage (Voc) of 638.3 mV and efficiency of 18.13% were fabricated. The result showed an improvement of about 13 mV on Voc compared to those of the reference solar cell fabricated with the reactive-ion etching back selective emitter and with Jsc of 36.90 mAcm−2, Voc of 625.7 mV, and efficiency of 17.60%. PMID:22823978

  9. Transferring resist microlenses into silicon by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Eisner, Martin; Schwider, Johannes

    1996-10-01

    Reactive ion etching (RIE) is known as an effective technique for high precision anisotropic etching with a minimum loss of the critical dimensions provided by the photoresist or other masking materials. RIE can also be used to transfer continuous forms such as spherical resist microlenses into substrate materials (e.g., quartz glass or silicon). The form of the lenses can be considerably controlled by changing the etch rate ratio between resist and the substrate. This was achieved by varying the etch gas compound, especially the amount of oxygen, during the etching or by changing the applied power. Measured etch rates for silicon are given to demonstrate the possibilities of lens shaping. The surface roughness of the etched lenses was one of the main problems. The roughness could be minimized by adding helium to the etch gases for heat removal and by increasing the resist rinse time after the wet chemical development.

  10. Controlling line-edge roughness and reactive ion etch lag in sub-150 nm features in borophosphosilicate glass

    SciTech Connect

    Bhatnagar, Parijat; Panda, Siddhartha; Edleman, Nikki L.; Allen, Scott D.; Wise, Richard; Mahorowala, Arpan

    2007-04-01

    We have developed a reactive ion etch (RIE) process in borophosphosilicate glass (BPSG) for 150 nm line-and-space features, where line-edge roughness (LER) complemented with RIE lag becomes a major issue. Effect of flow rates and carbon-to-fluorine atomic ratio of fluorohydrocarbon gases was utilized to achieve acceptable process window allowing lower radio frequency powers therefore obtaining acceptable LER and RIE lag in the high-resolution features etched into BPSG.

  11. Spinner For Etching Of Semiconductor Wafers

    NASA Technical Reports Server (NTRS)

    Lombardi, Frank

    1989-01-01

    Simple, inexpensive apparatus coats semiconductor wafers uniformly with hydrofluoric acid for etching. Apparatus made in part from small commercial electric-fan motor. Features bowl that collects acid. Silicon wafer placed on platform and centered on axis; motor switched on. As wafer spins, drops of hydrofluoric acid applied from syringe. Centrifugal force spreads acid across wafer in fairly uniform sheet.

  12. XeF2 gas-assisted focused-electron-beam-induced etching of GaAs with 30 nm resolution

    NASA Astrophysics Data System (ADS)

    Ganczarczyk, A.; Geller, M.; Lorke, A.

    2011-01-01

    We demonstrate the gas-assisted focused-electron-beam (FEB)-induced etching of GaAs with a resolution of 30 nm at room temperature. We use a scanning electron microscope (SEM) in a dual beam focused ion beam together with xenon difluoride (XeF2) that can be injected by a needle directly onto the sample surface. We show that the FEB-induced etching with XeF2 as a precursor gas results in isotropic and smooth etching of GaAs, while the etch rate depends strongly on the beam current and the electron energy. The natural oxide of GaAs at the sample surface inhibits the etching process; hence, oxide removal in combination with chemical surface passivation is necessary as a strategy to enable this high-resolution etching alternative for GaAs.

  13. Inductively Coupled Plasma Reactive Ion Etching of AlGaAsSb and InGaAsSb for Quaternary Antimonide MIM Thermophotovoltaics

    SciTech Connect

    Palmisiano, M. N.; Peake, G. M.; Shul, R. J.; Ashby, C. I.; Cederberg, J. G.; Hafich, M. J.; Biefeld, R. M.

    2002-10-01

    In this letter we report on the inductively coupled plasma reactive ion etching (ICP-RIE) of InGaAsSb and AlGaAsSb for the fabrication of quaternary monolithic interconnected module (MIM) thermophotovoltaic (TPV) devices. A rapid dry etch process is described that produces smooth surfaces using BCl[sub]3 for AlGaAsSb and InGaAsSb capped with GaSb. Uncapped InGaAsSb was etched by adding an H[sub]2 plasma preclean to reduce surface oxides. InGaAsSb etch rate was studied as a function of accelerating voltage, RF power, temperature and pressure. The etch conditions found for InGaAsSb were used for AlGaAsSb etching to determine the effectiveness for isolation of the MIM cells.

  14. Optimization of Track Etched Makrofol Etching Conditions for Short-term Exposure Duration

    NASA Astrophysics Data System (ADS)

    Moreno, V.; Font, Ll.

    Exposure time of nuclear track detectors at humid environments is normally limited to a few weeks because filter used to avoid humidity is not completely waterproof and, after several months, some parts of detector start to degrade. In other really extreme measurement conditions, like high aerosol content, high or low temperatures, etc., the exposure time also requires a reduction. Then detector detection limit becomes a problem, unless radon concentrations were high. In those cases where radon levels are not high enough a better detection efficiency is required. In our laboratory we use passive detectors based on the track etched Makrofol DE foil covered with aluminized Mylar and they are analyzed by means of an electrochemical etching. Our standard etching conditions allow analyzing detectors generally exposed for periods between three and six months. We have optimized our etching conditions to reduce the exposure time down to a month for common radon concentration values.

  15. Anodic etching of p-type cubic silicon carbide

    NASA Technical Reports Server (NTRS)

    Harris, G. L.; Fekade, K.; Wongchotigul, K.

    1992-01-01

    p-Type cubic silicon carbide was anodically etched using an electrolyte of HF:HCl:H2O. The etching depth was determined versus time with a fixed current density of 96.4 mA/sq cm. It was found that the etching was very smooth and very uniform. An etch rate of 22.7 nm/s was obtained in a 1:1:50 HF:HCl:H2O electrolyte.

  16. High index contrast polysiloxane waveguides fabricated by dry etching

    SciTech Connect

    Madden, S. J.; Zhang, M. Y.; Choi, D.-Y.; Luther-Davies, B.; Charters, R.

    2009-05-15

    The authors demonstrate the production of low loss enhanced index contrast waveguides by reactive ion etching of IPG trade mark sign polysiloxane thin films. The use of a silica mask and CHF{sub 3}/O{sub 2} etch gas led to large etch selectivity between the silica and IPG trade mark sign of >20 and etch rates of >100 nm/min. This work indicates that compact optical circuits could be successfully fabricated for telecommunication applications using polysiloxane films.

  17. Fabrication of particular structures of hexagonal boron nitride and boron-carbon-nitrogen layers by anisotropic etching

    NASA Astrophysics Data System (ADS)

    Vishwakarma, Riteshkumar; Sharma, Subash; Shinde, Sachin M.; Sharma, Kamal P.; Thangaraja, Amutha; Kalita, Golap; Tanemura, Masaki

    2016-05-01

    Anisotropic etching of hexagonal boron nitride (h-BN) and boron-carbon-nitrogen (BCN) basal plane can be an exciting platform to develop well-defined structures with interesting properties. Here, we developed an etching process of atomically thin h-BN and BCN layers to fabricate nanoribbons (NRs) and other distinct structures by annealing in H2 and Ar gas mixture. BCN and h-BN films are grown on Cu foil by chemical vapor deposition (CVD) using solid camphor and ammonia borane as carbon, nitrogen and boron source, respectively. Formation of micron size well-defined etched holes and NRs are obtained in both h-BN and BCN layers by the post growth annealing process. The etching process of h-BN and BCN basal plane to fabricate NRs and other structures with pronounced edges can open up new possibilities in 2D hybrid materials.

  18. Dopant Selective Reactive Ion Etching of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Okojie, Robert (Inventor)

    2016-01-01

    A method for selectively etching a substrate is provided. In one embodiment, an epilayer is grown on top of the substrate. A resistive element may be defined and etched into the epilayer. On the other side of the substrate, the substrate is selectively etched up to the resistive element, leaving a suspended resistive element.

  19. CR-39 track etching and blow-up method

    DOEpatents

    Hankins, Dale E.

    1987-01-01

    This invention is a method of etching tracks in CR-39 foil to obtain uniformly sized tracks. The invention comprises a step of electrochemically etching the foil at a low frequency and a "blow-up" step of electrochemically etching the foil at a high frequency.

  20. Electrochemical etching of p-n-GaN/AlGaN photoelectrodes

    NASA Astrophysics Data System (ADS)

    Usikov, A. S.; Helava, H.; Nikiforov, A.; Puzyk, M. V.; Papchenko, B. P.; Kovaleva, Yu. V.; Makarov, Yu. N.

    2016-05-01

    Specific features of etching of GaN/AlGaN p-n structures in a KOH-based electrolyte have been studied. It was found that the corrosion process first passes across p layers through vertical channels associated with threading structural defects. Then, the corrosion process occurs in the lateral direction along n layers of the structure, with local hollows and voids thereby formed. The lateral etching is due to the presence of positive piezoelectric charges at boundaries of n-AlGaN and n-GaN layers and positively charged ionized donors in the space-charge region of the p-n junction.

  1. Antireflective grassy surface on glass substrates with self-masked dry etching

    PubMed Central

    2013-01-01

    Although recently developed bio-inspired nanostructures exhibit superior optic performance, their practical applications are limited due to cost issues. We present highly transparent glasses with grassy surface fabricated with self-masked dry etch process. Simultaneously generated nanoclusters during reactive ion etch process with simple gas mixture (i.e., CF4/O2) enables lithography-free, one-step nanostructure fabrication. The resulting grassy surfaces, composed of tapered subwavelength structures, exhibit antireflective (AR) properties in 300 to 1,800-nm wavelength ranges as well as improved hydrophilicity for antifogging. Rigorous coupled-wave analysis calculation provides design guidelines for AR surface on glass substrates. PMID:24289255

  2. Production of energetic ions in plasma by ambipolar fields: Application to etching

    SciTech Connect

    Park, Wontaek; Tolmachev, Yu. N.; Volynets, V. N.; Pashkovskiy, V. G.

    2007-07-15

    A plasma accelerator based on inductively coupled plasma source, which is able to produce an axially directed flux of accelerated ions onto the wafer without applying the bias voltage, has been studied and utilized in a semiconductor etch process. Ion kinetic energies up to 60 eV have been measured for an absorbed power of about 800 W, while the plasma density was {approx}10{sup 10} cm{sup -3} at the plasma source exit. The experimental results show that the plasma accelerator can be used for an anisotropic etch process without the radio-frequency bias of the substrate.

  3. Ultimate intra-wafer critical dimension uniformity control by using lithography and etch tool corrections

    NASA Astrophysics Data System (ADS)

    Kubis, Michael; Wise, Rich; Reijnen, Liesbeth; Viatkina, Katja; Jaenen, Patrick; Luca, Melisa; Mernier, Guillaume; Chahine, Charlotte; Hellin, David; Kam, Benjamin; Sobieski, Daniel; Vertommen, Johan; Mulkens, Jan; Dusa, Mircea; Dixit, Girish; Shamma, Nader; Leray, Philippe

    2016-03-01

    With shrinking design rules, the overall patterning requirements are getting aggressively tighter. For the 7-nm node and below, allowable CD uniformity variations are entering the Angstrom region (ref [1]). Optimizing inter- and intra-field CD uniformity of the final pattern requires a holistic tuning of all process steps. In previous work, CD control with either litho cluster or etch tool corrections has been discussed. Today, we present a holistic CD control approach, combining the correction capability of the etch tool with the correction capability of the exposure tool. The study is done on 10-nm logic node wafers, processed with a test vehicle stack patterning sequence. We include wafer-to-wafer and lot-to-lot variation and apply optical scatterometry to characterize the fingerprints. Making use of all available correction capabilities (lithography and etch), we investigated single application of exposure tool corrections and of etch tool corrections as well as combinations of both to reach the lowest CD uniformity. Results of the final pattern uniformity based on single and combined corrections are shown. We conclude on the application of this holistic lithography and etch optimization to 7nm High-Volume manufacturing, paving the way to ultimate within-wafer CD uniformity control.

  4. Strong suppression of near-surface thermal transport by metal-assisted chemical etching of Si

    NASA Astrophysics Data System (ADS)

    Feser, Joseph; Cahill, David

    2013-03-01

    Recently, we reported that the thermal conductivity of Si nanowire arrays roughened by metal-assisted chemical etching (MAC-etch) is strongly correlated to both the magnitude of the roughness and a broadening of the one-phonon Raman linewidth. We hypothesized that microstructural disorder induced by the etching chemistry leads to changes in the Raman linewidth and reduced thermal conductivity. Here, we simplify the study of such effects by chemically roughening Si wafers instead of nanowires. We have studied the effects of various roughening procedures on the near-surface thermal transport properties using time-domain thermoreflectance. We find that the thermal conductance of the near-surface region is systematically reduced by the MAC-etch process, despite the expectation that pristine roughened surfaces should have increased conductance due to enhanced surface area. In addition, highly roughened surfaces show strong picosecond acoustic echoes with reflection coefficient indicative of a soft interface. These features are consistent with the presence of strong disorder or nanoporosity in the near-surface region created by the MAC-etch process.

  5. Chemically Etched Open Tubular and Monolithic Emitters for Nanoelectrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Page, Jason S.; Luo, Quanzhou; Moore, Ronald J.; Orton, Daniel J.; Tang, Keqi; Smith, Richard D.

    2006-11-15

    We have developed a new procedure for fabricating fused silica emitters for electrospray ionization-mass spectrometry (ESI-MS) in which the end of a bare fused silica capillary is immersed into aqueous hydrofluoric acid, and water is pumped through the capillary to prevent etching of the interior. Surface tension causes the etchant to climb the capillary exterior, and the etch rate in the resulting meniscus decreases as a function of distance from the bulk solution. Etching continues until the silica touching the hydrofluoric acid reservoir is completely removed, essentially stopping the etch process. The resulting emitters have no internal taper, making them much less prone to clogging compared to e.g. pulled emitters. The high aspect ratios and extremely thin walls at the orifice facilitate very low flow rate operation; stable ESI-MS signals were obtained for model analytes from 5-μm-diameter emitters at a flow rate of 5 nL/min with a high degree of inter-emitter reproducibility. In extensive evaluation, the etched emitters were found to enable approximately four times as many LC-MS analyses of proteomic samples before failing compared with conventional pulled emitters. The fabrication procedure was also employed to taper the ends of polymer monolith-containing silica capillaries for use as ESI emitters. In contrast to previous work, the monolithic material protrudes beyond the fused silica capillaries, improving the monolith-assisted electrospray process.

  6. Plasma Etching of n-Type 4H-SiC for Photoconductive Semiconductor Switch Applications

    NASA Astrophysics Data System (ADS)

    Ekinci, Huseyin; Kuryatkov, Vladimir V.; Mauch, Daniel L.; Dickens, James C.; Nikishin, Sergey A.

    2015-05-01

    Photoconductive semiconductor switches (PCSS) fabricated on high-purity semi-insulating 4H-SiC substrates (000) are capable of switching high currents in compact packages with long device lifetimes. A heavily doped n-type SiC epitaxial layer of appropriate thickness is required to form low-resistance ohmic contacts with these devices. In addition, to enhance the performance of the PCSSs, the SiC surface between the ohmic contacts must be extremely smooth. We report a chlorine-based, inductively coupled plasma reactive ion-etching process yielding n-type SiC epitaxial layers with the required smoothness. The rate of etching and post-etching surface morphology were dependent on plasma conditions. We found that the surface smoothness of epitaxial layers can be improved by including BCl3 in the argon-chlorine mixture. The optimum etching process yielded very smooth surfaces (˜0.3 nm RMS) at a relatively high rate of etching of ˜220 nm/min. This new fabrication approach significantly reduced the on-state resistance of the PCSS device and improved its durability of operation.

  7. Peculiarities of latent track etching in SiO2/Si structures irradiated with Ar, Kr and Xe ions

    NASA Astrophysics Data System (ADS)

    Al'zhanova, A.; Dauletbekova, A.; Komarov, F.; Vlasukova, L.; Yuvchenko, V.; Akilbekov, A.; Zdorovets, M.

    2016-05-01

    The process of latent track etching in SiO2/Si structures irradiated with 40Ar (38 MeV), 84Kr (59 MeV) and 132Xe (133 and 200 MeV) ions has been investigated. The experimental results of SiO2 etching in a hydrofluoric acid solution have been compared with the results of computer simulation based on the thermal spike model. It has been confirmed that the formation of a molten region along the swift ion trajectory with minimum radius of 3 nm can serve as a theoretical criterion for the reproducible latent track etching tracks in SiO2.

  8. Gold-thickness-dependent Schottky barrier height for charge transfer in metal-assisted chemical etching of silicon

    PubMed Central

    2013-01-01

    Large-area, vertically aligned silicon nanowires with a uniform diameter along the height direction were fabricated by combining in situ-formed anodic aluminum oxide template and metal-assisted chemical etching. The etching rate of the Si catalyzed using a thick Au mesh is much faster than that catalyzed using a thin one, which is suggested to be induced by the charge transport process. The thick Au mesh in contact with the Si produces a low Au/Si Schottky barrier height, facilitating the injection of electronic holes from the Au to the Si, thus resulting in a high etching rate. PMID:23618313

  9. Photoelectrochemical etching of silicon carbide (SiC) and its characterization

    NASA Technical Reports Server (NTRS)

    Collins, D. M.; Harris, G. L.; Wongchotigul, K.

    1995-01-01

    Silicon carbide (SiC) is an attractive semiconductor material for high speed, high density, and high temperature device applications due to its wide bandgap (2.2-3.2 eV), high thermal conductivity, and high breakdown electric field (4 x 10(exp 6) V/cm). An instrumental process in the fabrication of semiconductor devices is the ability to etch in a highly controlled and selective manner for direct patterning techniques. A novel technique in etching using electrochemistry is described. This procedure involves the ultraviolet (UV) lamp-assisted photoelectrochemical etching of n-type 3C- and 6H-SiC to enhance the processing capability of device structures in SiC. While under UV illumination, the samples are anodically biased in an HF based aqueous solution since SiC has photoconductive properties. In order for this method to be effective, the UV light must be able to enhance the production of holes in the SiC during the etching process thus providing larger currents with light from the photocurrents generated than those currents with no light. Otherwise dark methods would be used as in the case of p-type 3C-SiC. Experiments have shown that the I/V characteristics of the SiC-electrolyte interface reveal a minimum etch voltage of 3 V and 4 V for n- and p-type 3C-SiC, respectively. Hence it is possible for etch-stops to occur. Etch rates calculated have been as high as 0.67 micrometer/min for p-type, 1.4 micrometer/min for n-type, and 1.1 micrometer/min for pn layer. On n-type 3C- SiC, an oxide formation is present where after etching a yellowish layer corresponds to a low Si/C ratio and a white layer corresponds to a high Si/C ratio. P-type 3C-SiC shows a grayish layer. Additionally, n-type 6H-SiC shows a brown layer with a minimum etch voltage of 3 V.

  10. High T(sub c) Superconducting Bolometer on Chemically Etched 7 Micrometer Thick Sapphire

    NASA Technical Reports Server (NTRS)

    Lakew, B.; Brasunas, J. C.; Pique, A.; Fettig, R.; Mott, B.; Babu, S.; Cushman, G. M.

    1997-01-01

    A transition-edge IR detector, using a YBa2Cu3O(7-x) (YBCO) thin film deposited on a chemically etched, 7 micrometer thick sapphire substrate has been built. To our knowledge it is the first such high T(sub c) superconducting (HTS) bolometer on chemically thinned sapphire. The peak optical detectivity obtained is l.2 x 10(exp 10) cmHz(sup 1/2)/W near 4Hz. Result shows that it is possible to obtain high detectivity with thin films on etched sapphire with no processing after the deposition of the YBCO film. We discuss the etching process and its potential for micro-machining sapphire and fabricating 2-dimensional detector arrays with suspended sapphire membranes. A 30 micrometer thick layer of gold black provided IR absorption. Comparison is made with the current state of the art on silicon substrates.

  11. Automatic end-point detection of spray etching in application to mask making

    SciTech Connect

    Mizuno, F.; Kato, M.; Koizumi, T.; Mori, K.; Sagawara, K.; Takehana, Y.

    1985-06-01

    The development of high performance LSI's has increased the requirement for precise control of mask making in addition to that of wafer processing. One method for obtaining precise control is ''in-process'' end-point detection. End-point detection methods have previously been devised for thin film formation, such as thickness control of SOS (silicon-on-sapphire) epitaxial layers (1), homoepitaxial layers (2), and for plasma etching (3). In mask making, ''wet etching'' has been used due to thin Cr film deposited on mask blanks and to flat surface in comparison with the wafer fabrication. In this note, a novel method of the end-point detection used for the mask making will be reported; it is quite different from that used for the ''dry etching.''

  12. Versatile micropipette technology based on deep reactive ion etching and anodic bonding for biological applications

    NASA Astrophysics Data System (ADS)

    Lopez-Martinez, M. J.; Campo, E. M.; Caballero, D.; Fernandez, E.; Errachid, A.; Esteve, J.; Plaza, J. A.

    2009-10-01

    A novel, versatile and robust technology to manufacture transparent micropipettes, suitable for biological applications, is presented here. Up to three deep reactive ion etchings have been included in the manufacturing process, providing highly controlled geometry of reservoirs, connection cavities and inlet ports. Etching processes have been used for the definition of chip and reservoir and for nozzle release. Additionally, special design considerations have been developed to facilitate micro-to-macro fluidic connections. Implementation of anodic bonding to seal a glass substrate to the fluidic structure etched on Si, allowed observation of the flow inside the reservoir. Flow tests have been conducted by filling channels with different fluids. Flow was observed under an optical microscope, both during capillary filling and also during pumping. Dispensing has been demonstrated by functionalizing the surface of an AFM cantilever. Mechanical tests performed by piercing live mouse cells with FIB-sharpened micropipettes suggest the design is sturdy for biological piercing applications.

  13. Fabrication of sub-15 nm aluminum wires by controlled etching

    SciTech Connect

    Morgan-Wall, T.; Hughes, H. J.; Hartman, N.; Marković, N.; McQueen, T. M.

    2014-04-28

    We describe a method for the fabrication of uniform aluminum nanowires with diameters below 15 nm. Electron beam lithography is used to define narrow wires, which are then etched using a sodium bicarbonate solution, while their resistance is simultaneously measured in-situ. The etching process can be stopped when the desired resistance is reached, and can be restarted at a later time. The resulting nanowires show a superconducting transition as a function of temperature and magnetic field that is consistent with their smaller diameter. The width of the transition is similar to that of the lithographically defined wires, indicating that the etching process is uniform and that the wires are undamaged. This technique allows for precise control over the normal state resistance and can be used to create a variety of aluminum nanodevices.

  14. Multi-layer model vs. single-layer model for N and P doped poly layers in etch bias modeling

    NASA Astrophysics Data System (ADS)

    Li, Jianliang; Vidal-Russell, Ezequiel; Beale, Daniel; Wang, Chunqing; Melvin, Lawrence S., III

    2010-09-01

    In modern photolithography, ever smaller critical dimension (CD) budgets require tighter control over the entire process, demanding more accurate practice of optical proximity correction (OPC). In last decade, the model based OPC (MBOPC) has outpaced the rule based OPC (RBOPC) and become widely adopted in semiconductor industry. During the MBOPC process, the physical models are called to compute the signal values at the evaluation points and the design patterns are perturbed such that the final model contours are as close to the targets as possible. It has been demonstrated that in addition to simulating the optics and resist effects, the physical models must accommodate the pattern distortion due to etch process as well. While the etch process may be lumped with optics and resist processes into one model for the 65nm and above nodes, it can no longer be treated as small perturbations on photolithographic effects for more advanced nodes and it is highly desired to build a physics-based etch model formulations that differ from the conventional convolution-based process models used to simulate the optical and resist effect. Our previous studies proposed a novel non-linear etch modeling object in combination with conventional convolution kernels, which simulates the non-optics and non-resist proximity effect successfully. This study examines further the non-linear etch modeling method by checking the different behaviors of N and p doped layers which physically have different etching rates and should be represented differently in etch modeling. The experimental results indicate that the fitting accuracy is significantly improved when the data points are split into N and P groups and calibrated separately. The N and P layer etch models are used in staged MBOPCs and the results are compared with single-layer model as well.

  15. Actinometry of inductively coupled Cl{sub 2}/N{sub 2} plasmas for dry etching of GaAs

    SciTech Connect

    Brueckl, Tobias; Zull, Heribert

    2005-07-15

    Inductively coupled plasma dry etching of GaAs with Cl{sub 2}/N{sub 2}-containing plasmas and investigations of these plasmas with optical emission spectroscopy and actinometry are presented. The results of actinometry were revised to allow the comparison of relative ground-state densities at different pressures. The obtained relative ground-state densities of N{sub 2}, Cl{sub 2}, and Cl (I) are presented as functions of the process parameters [rf power, pressure, and Cl{sub 2}/(Cl{sub 2}+N{sub 2}) ratio]. Cl (I) relative ground-state densities were found to be linearly connected to the pressure and the Cl{sub 2}/(Cl{sub 2}+N{sub 2}) ratio. GaAs etch rates up to 3 {mu}m/min were obtained, while etch rates of the photoresist mask did not exceed 0.95 {mu}m/min. The impact of the rf power changes on the etch rates was negligible. Plotting the etch rates against the process parameters revealed a linear relationship between the etch rates and the pressure and between the etch rates and the Cl{sub 2}/(Cl{sub 2}+N{sub 2}) ratio. Therefore a correlation between the Cl (I) relative ground-state density measured in plasmas without wafer and GaAs and the photoresist mask etch rate was found. All GaAs dry etching examined in this investigation was found to take place in a reactant-limited regime with Cl (I) as the rate-limiting species.

  16. Fabrication of InGaAs/InP DBR laser with butt-coupled passive waveguide utilizing selective wet etching

    NASA Astrophysics Data System (ADS)

    Mi, Junping; Yu, Hongyan; Yuan, Lijun; Liang, Song; Kan, Qiang; Pan, Jiaoqing

    2014-11-01

    We investigated the etching process especially for the integrated InGaAs/InP multiquantum-well laser. Two different ways of etching process were demonstrated, which are RIE followed by selective wet etching and selective wet etching only. The latter one showed ideal interface between active region and passive waveguide after regrowth. This etching process is simpler and more effective than the first one. Using this process, we also fabricated a 1.79-μm DBR laser with 350-μm active region and 400-μm passive waveguide. The output power and threshold current and were demonstrated as a function of temperature. The wavelength tuning characters were investigated with current and temperature changes. It is demonstrated that this etching process can be successfully used to fabricate integrated photonic devices with InGaAs/InP materials and the DBR laser can be a candidate for gas sensing system due to the single mode and large tuning range.

  17. III-Nitride Blue Laser Diode with Photoelectrochemically Etched Current Aperture

    NASA Astrophysics Data System (ADS)

    Megalini, Ludovico

    distance. In this dissertation it is presented the first nitride blue edge emitting LD with a photoelectrochemical etched current aperture (CA-LD) into the device active region. Photoelectrochemical etching (PECE) has emerged as a powerful wet etching technique for III-nitride compounds. Beyond the advantages of wet etching technique, PECE offers bandgap selectivity, which is particularly desirable because it allows more freedom in designing new and advanced devices with higher performances. In the first part of this thesis a review of PECE is presented, and it is shown how it can be used to achieve a selective and controllable deep undercut of the active region of LEDs and LDs, in particular the selective PECE of MQW active region of (10-10) m-plane and (20-2-1) plane structures is reported. In the second part of this thesis, the fabrication flow process of the CA-LD is described. The performance of these devices is compared with that of shallow etched ridge LDs with a nominally identical epitaxial structure and active region width and it is experimentally shown that the CA-LD design has superior performance. CW operation of a (20-2-1) CA-LD with a 1.5 microm wide active region is demonstrated. Finally, in the third and last part of this thesis, the CA-LD performance is discussed in more details, in particular, an analysis of optical scattering losses caused by the rough edges of the remnant PEC etched active region is presented.

  18. Fabrication of microstructure array directly on β-phase poly(vinylidene fluoride) thin film by O2 reactive ion etching

    NASA Astrophysics Data System (ADS)

    Miki, Hirofumi; Matsui, G.; Kanda, M.; Tsuchitani, S.

    2015-03-01

    The ability to pattern a thin film of poly(vinylidene fluoride) (PVDF), a piezoelectric, pyroelectric and ferroelectric polymer, has potential applications in the fields of microelectromechanical systems (MEMS), nonlinear optics and nonvolatile ferroelectric random access memory technology. Low pressure O2 reactive ion etching (RIE) was employed to realize fine pitch microstructures on a β-phase PVDF (β-PVDF) film for the first time; a line and space (70/130 μm) microstructure array with a height of over 30 μm was fabricated. Different to the traditional method of PDMS molding, the proposed technology did not result in significant loss of piezoelectricity. Furthermore, unlike the x-ray photo-etching method, there was no etching saturation limit with the proposed method. Here, we introduce the fabrication process technology in detail and report on the etching properties of the β-PVDF film under different process conditions. The effect of process variables, such as supplied gas flow, applied RF power and etch time, on the PVDF etching characteristics were investigated in detail. The RF power and etch time showed a more predominant influence on PVDF etching progress than the gas flow. The etched depth was linearly increased with the etch time and the amount of RF power. Etching rates over 10 μm h-1 were achieved and increased linearly with the applied RF power. By means of a responding photomask design and control of process conditions, much finer and higher microstructure arrays are also possible.

  19. Diagnostic for Plasma Enhanced Chemical Vapor Deposition and Etch Systems

    NASA Technical Reports Server (NTRS)

    Cappelli, Mark A.

    1999-01-01

    In order to meet NASA's requirements for the rapid development and validation of future generation electronic devices as well as associated materials and processes, enabling technologies ion the processing of semiconductor materials arising from understanding etch chemistries are being developed through a research collaboration between Stanford University and NASA-Ames Research Center, Although a great deal of laboratory-scale research has been performed on many of materials processing plasmas, little is known about the gas-phase and surface chemical reactions that are critical in many etch and deposition processes, and how these reactions are influenced by the variation in operating conditions. In addition, many plasma-based processes suffer from stability and reliability problems leading to a compromise in performance and a potentially increased cost for the semiconductor manufacturing industry. Such a lack of understanding has hindered the development of process models that can aid in the scaling and improvement of plasma etch and deposition systems. The research described involves the study of plasmas used in semiconductor processes. An inductively coupled plasma (ICP) source in place of the standard upper electrode assembly of the Gaseous Electronics Conference (GEC) radio-frequency (RF) Reference Cell is used to investigate the discharge characteristics and chemistries. This ICP source generates plasmas with higher electron densities (approximately 10(exp 12)/cu cm) and lower operating pressures (approximately 7 mTorr) than obtainable with the original parallel-plate version of the GEC Cell. This expanded operating regime is more relevant to new generations of industrial plasma systems being used by the microelectronics industry. The motivation for this study is to develop an understanding of the physical phenomena involved in plasma processing and to measure much needed fundamental parameters, such as gas-phase and surface reaction rates. species

  20. Removal and deposition efficiencies of the long-lived 222Rn daughters during etching of germanium surfaces

    NASA Astrophysics Data System (ADS)

    Zuzel, G.; Wójcik, M.; Majorovits, B.; Lampert, M. O.; Wendling, P.

    2012-06-01

    Removal and deposition efficiencies of the long-lived 222Rn daughters during etching from and onto surfaces of standard and high purity germanium were investigated. The standard etching procedure of Canberra-France used during production of high purity n-type germanium diodes was applied to germanium discs, which have been exposed earlier to a strong radon source for deposition of its progenies. An uncontaminated sample was etched in a solution containing 210Pb, 210Bi and 210Po. All isotopes were measured before and after etching with appropriate detectors. In contrast to copper and stainless steel, they were removed from germanium very efficiently. However, the reverse process was also observed. Considerable amounts of radioactive lead, bismuth and polonium isotopes present initially in the artificially polluted etchant were transferred to the clean high purity surface during processing of the sample.

  1. Fabrication of single-crystal silicon nanotubes with sub-10 nm walls using cryogenic inductively coupled plasma reactive ion etching

    NASA Astrophysics Data System (ADS)

    Li, Zhiqin; Chen, Yiqin; Zhu, Xupeng; Zheng, Mengjie; Dong, Fengliang; Chen, Peipei; Xu, Lihua; Chu, Weiguo; Duan, Huigao

    2016-09-01

    Single-crystal silicon nanostructures have attracted much attention in recent years due in part to their unique optical properties. In this work, we demonstrate direct fabrication of single-crystal silicon nanotubes with sub-10 nm walls which show low reflectivity. The fabrication was based on a cryogenic inductively coupled plasma reactive ion etching process using high-resolution hydrogen silsesquioxane nanostructures as the hard mask. Two main etching parameters including substrate low-frequency power and SF6/O2 flow rate ratio were investigated to determine the etching mechanism in the process. With optimized etching parameters, high-aspect-ratio silicon nanotubes with smooth and vertical sub-10 nm walls were fabricated. Compared to commonly-used antireflection silicon nanopillars with the same feature size, the densely packed silicon nanotubes possessed a lower reflectivity, implying possible potential applications of silicon nanotubes in photovoltaics.

  2. Fabrication of single-crystal silicon nanotubes with sub-10 nm walls using cryogenic inductively coupled plasma reactive ion etching.

    PubMed

    Li, Zhiqin; Chen, Yiqin; Zhu, Xupeng; Zheng, Mengjie; Dong, Fengliang; Chen, Peipei; Xu, Lihua; Chu, Weiguo; Duan, Huigao

    2016-09-01

    Single-crystal silicon nanostructures have attracted much attention in recent years due in part to their unique optical properties. In this work, we demonstrate direct fabrication of single-crystal silicon nanotubes with sub-10 nm walls which show low reflectivity. The fabrication was based on a cryogenic inductively coupled plasma reactive ion etching process using high-resolution hydrogen silsesquioxane nanostructures as the hard mask. Two main etching parameters including substrate low-frequency power and SF6/O2 flow rate ratio were investigated to determine the etching mechanism in the process. With optimized etching parameters, high-aspect-ratio silicon nanotubes with smooth and vertical sub-10 nm walls were fabricated. Compared to commonly-used antireflection silicon nanopillars with the same feature size, the densely packed silicon nanotubes possessed a lower reflectivity, implying possible potential applications of silicon nanotubes in photovoltaics.

  3. Plasma etching, texturing, and passivation of silicon solar cells

    SciTech Connect

    Ruby, D.S.; Yang, P.; Zaidi, S.; Brueck, S.; Roy, M.; Narayanan, S.

    1998-11-01

    The authors improved a self-aligned emitter etchback technique that requires only a single emitter diffusion and no alignments to form self-aligned, patterned-emitter profiles. Standard commercial screen-printed gridlines mask a plasma-etchback of the emitter. A subsequent PECVD-nitride deposition provides good surface and bulk passivation and an antireflection coating. The authors used full-size multicrystalline silicon (mc-Si) cells processed in a commercial production line and performed a statistically designed multiparameter experiment to optimize the use of a hydrogenation treatment to increase performance. They obtained an improvement of almost a full percentage point in cell efficiency when the self-aligned emitter etchback was combined with an optimized 3-step PECVD-nitride surface passivation and hydrogenation treatment. They also investigated the inclusion of a plasma-etching process that results in a low-reflectance, textured surface on multicrystalline silicon cells. Preliminary results indicate reflectance can be significantly reduced without etching away the emitter diffusion.

  4. Chemical etching of deformation sub-structures in quartz

    NASA Astrophysics Data System (ADS)

    Wegner, M. W.; Christie, J. M.

    1983-02-01

    Chemical etching of dislocations has been studied in natural and synthetic quartz single crystals, in deformed synthetic quartz and in naturally and experimentally deformed quartzites. The ability of different etchants to produce polished or preferentially etched surfaces on quartz is described. Dislocation etching was achieved on all crystal planes examined by using a saturated solution of ammonium bifluoride as the etchant. Appropriate etching times were determined for etching quartzites for grain size, subgrain boundaries, deformation lamellae, dislocations and twins. Growth and polished surfaces of synthetic single crystal quartz were similarly etched and dislocation etch pits, characteristic of various orientations were found. The use of ammonium bifluoride proved to be expecially advantageous for the basal plane, producing a polished surface with etch pits, suitable for dislocation etch pit counting. “Double” etch pits have been found on Dauphiné twin boundaries on the basal plane and the first order prism, using this etchant. Slip lines and deformation bands were suitably etched on deformed synthetic crystal surfaces for identification of the slip planes. Other acidic etchants have been explored and their application to the study of deformation structures in quartz crystals is discussed.

  5. Effects of N{sub 2} addition on chemical dry etching of silicon oxide layers in F{sub 2}/N{sub 2}/Ar remote plasmas

    SciTech Connect

    Hwang, J.Y.; Kim, D.J.; Lee, N.-E.; Jang, Y.C.; Bae, G.H.

    2006-07-15

    In this study, chemical dry etching characteristics of silicon oxide layers were investigated in the F{sub 2}/N{sub 2}/Ar remote plasmas. A toroidal-type remote plasma source was used for the generation of remote plasmas. The effects of additive N{sub 2} gas on the etch rates of various silicon oxide layers deposited using different deposition techniques and precursors were investigated by varying the various process parameters, such as the F{sub 2} flow rate, the additive N{sub 2} flow rate, and the substrate temperature. The etch rates of the various silicon oxide layers at room temperature were initially increased and then decreased with the N{sub 2} flow increased, which indicates an existence of the maximum etch rates. Increase in the oxide etch rates under the decreased optical emission intensity of the F radicals with the N{sub 2} flow increased implies that the chemical etching reaction is in the chemical reaction-limited regime, where the etch rate is governed by the surface chemical reaction rather than the F radical density. The etch rates of the silicon oxide layers were also significantly increased with the substrate temperature increased. In the present experiments, the F{sub 2} gas flow, the additive N{sub 2} flow rate, and the substrate temperature were found to be the critical parameters in determining the etch rate of the silicon oxide layers.

  6. Si nanowires arrays fabricated by wet chemical etching for antireflection and self-cleaning

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Xiaotao; Lai, Wuxing; Tang, Zirong

    2011-11-01

    Here we report a simple and cost effective fabrication technique, which created large area vertical Si nanowires (diameter in ~200 nm) by means of silver induced wet chemical etching on single crystalline Si substrates. By this technique, Si nanowires were fabricated on single crystalline in aqueous 5M HF and 0.02M AgNO3 solution at room temperature. The scanning electron microscope (SEM) images indicate that etched silicon wafers consist of dense and nearly vertically aligned one-dimensional nanostructures. Length of Si nanowires was found to increase linearly with etching time (0-300 min). The mechanism of vertical nanowires formation can be understood as being a self-assembled Ag induced selective etching process based on the localized microscopic electrochemical cell model. A low reflectivity averaged ~1.7% from 450 to 790 nm was observed. The nanometer scale rough surface can make water droplet either in the so-called Wenzel or the Cassie regime, which can increase contact angle (CA). High CA makes the surface hydrophobicity and self-cleaning. Water CA (150°) was observed on the etched Si surface. Such antireflection (AR) and self-cleaning surface may have potential applications for silicon solar cells.

  7. Si nanowires arrays fabricated by wet chemical etching for antireflection and self-cleaning

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Xiaotao; Lai, Wuxing; Tang, Zirong

    2012-02-01

    Here we report a simple and cost effective fabrication technique, which created large area vertical Si nanowires (diameter in ~200 nm) by means of silver induced wet chemical etching on single crystalline Si substrates. By this technique, Si nanowires were fabricated on single crystalline in aqueous 5M HF and 0.02M AgNO3 solution at room temperature. The scanning electron microscope (SEM) images indicate that etched silicon wafers consist of dense and nearly vertically aligned one-dimensional nanostructures. Length of Si nanowires was found to increase linearly with etching time (0-300 min). The mechanism of vertical nanowires formation can be understood as being a self-assembled Ag induced selective etching process based on the localized microscopic electrochemical cell model. A low reflectivity averaged ~1.7% from 450 to 790 nm was observed. The nanometer scale rough surface can make water droplet either in the so-called Wenzel or the Cassie regime, which can increase contact angle (CA). High CA makes the surface hydrophobicity and self-cleaning. Water CA (150°) was observed on the etched Si surface. Such antireflection (AR) and self-cleaning surface may have potential applications for silicon solar cells.

  8. Wavelength Dependence of UV Effect on Etch Rate and Noise in CR-39

    NASA Astrophysics Data System (ADS)

    Wiesner, Micah; Traynor, Nathan; McLean, James; Padalino, Stephen; Sangster, Craig; McCluskey, Michelle

    2014-10-01

    The use of CR-39 plastic as a SSNTD is an effective technique for recovering data in high-energy particle experiments including inertial confinement fusion. To reveal particle tracks after irradiation, CR-39 is chemically etched at elevated temperatures with NaOH, producing signal pits at the nuclear track sites that are measurable by an optical microscope. CR-39 pieces also exhibit etch-induced noise, either surface roughness or pit-like features not caused by nuclear particles, which negatively affects the ability of observers to distinguish actual pits. When CR-39 is exposed to high intensity UV light after nuclear irradiation and before etching, an increase in etch rates and pit diameters is observed. UV exposure can also increase noise, which in the extreme can distort the shapes of particle pits. Analyzing the effects of different wavelengths in the UV spectrum we have determined that light of the wavelength 255 nm increases etch rates and pit diameters while causing less background noise than longer UV wavelengths. Preliminary research indicates that heating CR-39 to elevated temperatures (~80 °C) during UV exposure also improves the signal-to-noise ratio for this process. Funded in part by a grant from the DOE through the Laboratory for Laser Energetics.

  9. Low temperature dry etching of chromium towards control at sub-5 nm dimensions

    NASA Astrophysics Data System (ADS)

    Staaks, Daniel; Yang, XiaoMin; Lee, Kim Y.; Dhuey, Scott D.; Sassolini, Simone; Rangelow, Ivo W.; Olynick, Deirdre L.

    2016-10-01

    Patterned chromium and its compounds are crucial materials for nanoscale patterning and chromium based devices. Here we investigate how temperature can be used to control chromium etching using chlorine/oxygen gas mixtures. Oxygen/chlorine ratios between 0% and 100% and temperatures between -100 °C and +40 °C are studied. Spectroscopic ellipsometry is used to precisely measure rates, chlorination, and the thickness dependence of n and k. Working in the extremes of oxygen content (very high or very low) and lower temperatures, we find rates can be controlled to nanometers per minute. Activation energies are measured and show that etch mechanisms are both temperature and oxygen level dependent. Furthermore, we find that etching temperature can manipulate the surface chemistry. One surprising consequence is that at low oxygen levels, Etching rates increase with decreasing temperature. Preliminary feature-profile studies show the extremes of temperature and oxygen provide advantages over commonly used room temperature processing conditions. One example is with higher ion energies at -100 °C, where etching products deposit.

  10. Low temperature dry etching of chromium towards control at sub-5 nm dimensions.

    PubMed

    Staaks, Daniel; Yang, XiaoMin; Lee, Kim Y; Dhuey, Scott D; Sassolini, Simone; Rangelow, Ivo W; Olynick, Deirdre L

    2016-10-14

    Patterned chromium and its compounds are crucial materials for nanoscale patterning and chromium based devices. Here we investigate how temperature can be used to control chromium etching using chlorine/oxygen gas mixtures. Oxygen/chlorine ratios between 0% and 100% and temperatures between -100 °C and +40 °C are studied. Spectroscopic ellipsometry is used to precisely measure rates, chlorination, and the thickness dependence of n and k. Working in the extremes of oxygen content (very high or very low) and lower temperatures, we find rates can be controlled to nanometers per minute. Activation energies are measured and show that etch mechanisms are both temperature and oxygen level dependent. Furthermore, we find that etching temperature can manipulate the surface chemistry. One surprising consequence is that at low oxygen levels, Etching rates increase with decreasing temperature. Preliminary feature-profile studies show the extremes of temperature and oxygen provide advantages over commonly used room temperature processing conditions. One example is with higher ion energies at -100 °C, where etching products deposit.

  11. Low temperature dry etching of chromium towards control at sub-5 nm dimensions.

    PubMed

    Staaks, Daniel; Yang, XiaoMin; Lee, Kim Y; Dhuey, Scott D; Sassolini, Simone; Rangelow, Ivo W; Olynick, Deirdre L

    2016-10-14

    Patterned chromium and its compounds are crucial materials for nanoscale patterning and chromium based devices. Here we investigate how temperature can be used to control chromium etching using chlorine/oxygen gas mixtures. Oxygen/chlorine ratios between 0% and 100% and temperatures between -100 °C and +40 °C are studied. Spectroscopic ellipsometry is used to precisely measure rates, chlorination, and the thickness dependence of n and k. Working in the extremes of oxygen content (very high or very low) and lower temperatures, we find rates can be controlled to nanometers per minute. Activation energies are measured and show that etch mechanisms are both temperature and oxygen level dependent. Furthermore, we find that etching temperature can manipulate the surface chemistry. One surprising consequence is that at low oxygen levels, Etching rates increase with decreasing temperature. Preliminary feature-profile studies show the extremes of temperature and oxygen provide advantages over commonly used room temperature processing conditions. One example is with higher ion energies at -100 °C, where etching products deposit. PMID:27606715

  12. Formation of Mach angle profiles during wet etching of silica and silicon nitride materials

    NASA Astrophysics Data System (ADS)

    Ghulinyan, M.; Bernard, M.; Bartali, R.; Pucker, G.

    2015-12-01

    In integrated circuit technology peeling of masking photoresist films is a major drawback during the long-timed wet etching of materials. It causes an undesired film underetching, which is often accompanied by a formation of complex etch profiles. Here we report on a detailed study of wedge-shaped profile formation in a series of silicon oxide, silicon oxynitride and silicon nitride materials during wet etching in a buffered hydrofluoric acid (BHF) solution. The shape of etched profiles reflects the time-dependent adhesion properties of the photoresist to a particular material and can be perfectly circular, purely linear or a combination of both, separated by a knee feature. Starting from a formal analogy between the sonic boom propagation and the wet underetching process, we model the wedge formation mechanism analytically. This model predicts the final form of the profile as a function of time and fits the experimental data perfectly. We discuss how this knowledge can be extended to the design and the realization of optical components such as highly efficient etch-less vertical tapers for passive silicon photonics.

  13. Properties of TNF-1 track etch detector

    NASA Astrophysics Data System (ADS)

    Ogura, K.; Asano, M.; Yasuda, N.; Yoshida, M.

    2001-12-01

    We have developed a new plastic track etch detector labeled TNF-1, which is the copolymer of CR-39 monomer with N-isopropylacrylamide (NIPAAm). It was found that copoly(CR-39/NIPAAm/ antioxidant) composed in weight ratio of 99/1/0.01 is highly sensitive to low linear energy transfer (LET) particles in the region below 10 keV/μm of LET 200 eV. TNF-1 is the most sensitive plastic track etch detector reported so far and is able to record normally incident protons up to the energy of 27 MeV. This paper gives results of our studies on the track responses of TNF-1 as well as the brief results obtained by the performance tests of TNF-1 in various dosimetric experiments such as space radiation dosimetry, dosimetry for heavy ion cancer therapy and neutron dosimetry. These results are compared with the results obtained for CR-39 track detectors.

  14. Profile Evolution Simulation in Etching Systems Using Level Set Methods

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Govindan, T. R.; Meyyappan, M.

    1998-01-01

    Semiconductor device profiles are determined by the characteristics of both etching and deposition processes. In particular, a highly anisotropic etch is required to achieve vertical sidewalls. However, etching is comprised of both anisotropic and isotropic components, due to ion and neutral fluxes, respectively. In Ar/Cl2 plasmas, for example, neutral chlorine reacts with the Si surfaces to form silicon chlorides. These compounds are then removed by the impinging ion fluxes. Hence the directionality of the ions (and thus the ion angular distribution function, or IAD), as well as the relative fluxes of neutrals and ions determines the amount of undercutting. One method of modeling device profile evolution is to simulate the moving solid-gas interface between the semiconductor and the plasma as a string of nodes. The velocity of each node is calculated and then the nodes are advanced accordingly. Although this technique appears to be relatively straightforward, extensive looping schemes are required at the profile corners. An alternate method is to use level set theory, which involves embedding the location of the interface in a field variable. The normal speed is calculated at each mesh point, and the field variable is updated. The profile comers are more accurately modeled as the need for looping algorithms is eliminated. The model we have developed is a 2-D Level Set Profile Evolution Simulation (LSPES). The LSPES calculates etch rates of a substrate in low pressure plasmas due to the incident ion and neutral fluxes. For a Si substrate in an Ar/C12 gas mixture, for example, the predictions of the LSPES are identical to those from a string evolution model for high neutral fluxes and two different ion angular distributions.(2) In the figure shown, the relative neutral to ion flux in the bulk plasma is 100 to 1. For a moderately isotropic ion angular distribution function as shown in the cases in the left hand column, both the LSPES (top row) and rude's string

  15. Shapes of agglomerates in plasma etching reactors

    SciTech Connect

    Huang, F.Y.; Kushner, M.J.

    1997-05-01

    Dust particle contamination of wafers in reactive ion etching (RIE) plasma tools is a continuing concern in the microelectronics industry. It is common to find that particles collected on surfaces or downstream of the etch chamber are agglomerates of smaller monodisperse spherical particles. The shapes of the agglomerates vary from compact, high fractal dimension structures to filamentary, low fractal dimension structures. These shapes are important with respect to the transport of particles in RIE tools under the influence electrostatic and ion drag forces, and the possible generation of polarization forces. A molecular dynamics simulation has been developed to investigate the shapes of agglomerates in plasma etching reactors. We find that filamentary, low fractal dimension structures are generally produced by smaller ({lt}100s nm) particles in low powered plasmas where the kinetic energy of primary particles is insufficient to overcome the larger Coulomb repulsion of a compact agglomerate. This is analogous to the diffusive regime in neutral agglomeration. Large particles in high powered plasmas generally produce compact agglomerates of high fractal dimension, analogous to ballistic agglomeration of neutrals. {copyright} {ital 1997 American Institute of Physics.}

  16. Etching of moldavities under natural conditions

    NASA Technical Reports Server (NTRS)

    Knobloch, V.; Knoblochova, Z.; Urbanec, Z.

    1983-01-01

    The hypothesis that a part of the lechatellierites which originated by etching from a basic moldavite mass became broken off after deposition of moldavite in the sedimentation layer is advanced. Those found close to the original moldavite were measured for statistical averaging of length. The average length of lechatelierite fibers per cubic mm of moldavite mass volume was determined by measurement under a microscope in toluene. The data were used to calculate the depth of the moldavite layer that had to be etched to produce the corresponding amount of lechatelierite fragments. The calculations from five "fields" of moldavite surface, where layers of fixed lechatelierite fragments were preserved, produced values of 2.0, 3.1, 3.5, 3.9 and 4.5. Due to inadvertent loss of some fragments the determined values are somewhat lower than those found in references. The difference may be explained by the fact that the depth of the layer is only that caused by etching after moldavite deposition.

  17. Photoluminescence of etched SiC nanowires

    NASA Astrophysics Data System (ADS)

    Stewart, Polite D., Jr.; Rich, Ryan; Zerda, T. W.

    2010-10-01

    SiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100^oC and 1350^oC. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The compound possesses a high melting point, high thermal conductivity, and excellent wear resistance. The surface of the SiC nanowires after formation is covered by an amorphous layer. The composition of that layer is not fully understood, but it is believed that in addition to amorphous SiC it contains various carbon and silicon compounds, and SiO2. The objective of the research was to modify the surface structure of these SiC nanowires. Modification of the surface was done using the wet etching method. The etched nanowires were then analyzed using Fourier Transform Infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and photoluminescence (PL). FTIR and TEM analysis provided valid proof that the SiC nanowires were successfully etched. Also, the PL results showed that the SiC nanowire core did possess a fluorescent signal.

  18. Combining retraction edge lithography and plasma etching for arbitrary contour nanoridge fabrication

    NASA Astrophysics Data System (ADS)

    Zhao, Yiping; Jansen, Henri; de Boer, Meint; Berenschot, Erwin; Bouwes, Dominique; Gironès, Miriam; Huskens, Jurriaan; Tas, Niels

    2010-09-01

    Edge lithography in combination with fluorine-based plasma etching is employed to avoid the dependence on crystal orientation in single crystal silicon to create monolithic nanoridges with arbitrary contours. This is demonstrated by using a mask with circular structures and Si etching at cryogenic temperature with SF6+O2 plasma mixtures. Initially, the explored etch recipe was used with Cr as the masking material. Although nanoridges with perfect vertical sidewalls have been achieved, Cr causes severe sidewall roughness due to line edge roughness. Therefore, an SU-8 polymer is used instead. Although the SU-8 pattern definition needs further improvement, we demonstrate the possibility of fabricating Si nanoridges of arbitrary contours providing a width below 50 nm and a height between 25 and 500 nm with smooth surface finish. Artifacts in the ridge profile are observed and are mainly caused by the bird's beak phenomenon which is characteristic for the used LOCOS process.

  19. The use of Reactive Ion Etching for obtaining “free” silica nano test tubes

    NASA Astrophysics Data System (ADS)

    Buyukserin, Fatih; Martin, Charles R.

    2010-10-01

    Silica nano test tubes are one-dimensional inorganic nanostructures with several biotechnological applications including biosensing, magnetic resonance imaging, and targeted cancer therapeutics. They are generally prepared by sol-gel deposition of silica to nanoporous alumina templates. Preparing samples composed of isolated free silica nano test tubes can be a challenging process due to the conformal coating of silica on the template. This causes the formation of a top-surface silica layer which laterally connects the nano test tubes. Herein, we detailed the use of Reactive Ion Etching to remove this top-surface silica layer which yields free silica nano test tubes with template dissolution. Compared with the mechanical polishing approach, Reactive Ion Etching treatment allows a fine manipulation ability of the surface material at the nanoscale level. When used excessively, Reactive Ion Etching causes an orifice closing phenomenon that may be employed to create novel one-dimensional nanocapsules.

  20. Fabrication of axicon microlenses on capillaries and microstructured fibers by wet etching.

    PubMed

    Bachus, Kyle; Filho, Elton Soares de Lima; Wlodarczyk, Kamila; Oleschuk, Richard; Messaddeq, Younes; Loock, Hans-Peter

    2016-09-01

    A facile method is presented for the fabrication of microlenses at the facet of fused silica capillaries and microstructured fibers. After submersion in hydrogen fluoride solution water is pumped slowly through the center hole of the capillary microchannel to create an etchant gradient extending from the capillary axis. The desired axicon angle is generated by adjusting the etching time and/or concentration of the etchant. Similarly, flow- assisted HF etching of a custom microstructured fiber containing nine microchannels produces nine individual microlenses simultaneously at the fiber facet, where each microaxicon lens shows a similar focusing pattern. A theoretical model of the flow-assisted etching process is used to determine the axicon angle and post angle. Also, a simple ray-based model was applied to characterize the focusing properties of the microaxicons in good agreement with experimental observations. PMID:27607641

  1. Etch Effects on Surface loss in High Quality Aluminum on Silicon Superconducting Coplanar Resonators

    NASA Astrophysics Data System (ADS)

    Dunsworth, Andrew; Megrant, Anthony; Barends, Rami; Chen, Yu; Hoi, Iochun; Jeffrey, Evan; Mutus, Josh; Roushan, Pedram; Campbell, Brooks; Chen, Zijun; Chiaro, Ben; Kelly, Julian; Neill, Charles; O'Malley, Peter; Quintana, Chris; Sank, Daniel; Vainsencher, Amit; Wenner, Jim; White, Ted; Cleland, Andrew; Martinis, John; Martinis Group Team

    2014-03-01

    Superconducting coplanar resonators are a powerful tool for studying capacitive loss from two level states (TLS's) in superconducting qubits. We have found evidence that standard processing of aluminum on sapphire superconducting devices leaves behind ~2 nm organic residues which can contribute to loss at the Q >106 level that we are presently working with. Removing these residues is possible on a silicon substrate as it allows various sidewall etchings and profilings via chemical and physical etches. I will present recent Q factor measurements of aluminum on silicon resonators that were defined through a variety of etching conditions. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), through the Army Research Office grant JMAR-05.

  2. Nanopattern Profile Control Technology Using Reactive Ion Etching for 100 GB Optical Disc Mastering

    NASA Astrophysics Data System (ADS)

    Fujimura, Megumi; Hosoda, Yasuo; Katsumura, Masahiro; Kobayashi, Masaki; Kitahara, Hiroaki; Hashimoto, Kazunobu; Kasono, Osamu; Iida, Tetsuya; Kuriyama, Kazumi; Yokogawa, Fumihiko

    2006-02-01

    We had developed an electron beam recorder (EBR) and studied a process technology for high-density optical disc mastering. In this study, we aimed at controlling a nanopattern profile by adopting inductively coupled plasma reactive ion etching (ICP-RIE) under simple conditions. To control a pattern inclination angle, we introduced an etching power ratio of antenna to bias and investigated the relationship. From the results of our investigation, we confirmed that inclination angle depended on etching power ratio linearly. Furthermore, in the case of a 100 GB read-only memory (ROM) equivalent pattern, we formed two kinds of inclined pattern by adopting ICP-RIE. We evaluated line edge roughness (LER) to determine the difference in pit profile accurately. As the result, we confirmed that LER was improved at a steep inclination angle. In addition, we applied ICP-RIE to a 300 GB ROM pattern.

  3. GaN nanowire arrays by a patterned metal-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Wang, K. C.; Yuan, G. D.; Wu, R. W.; Lu, H. X.; Liu, Z. Q.; Wei, T. B.; Wang, J. X.; Li, J. M.; Zhang, W. J.

    2016-04-01

    We developed an one-step and two-step metal-assisted chemical etching method to produce self-organized GaN nanowire arrays. In one-step approach, GaN nanowire arrays are synthesized uniformly on GaN thin film surface. However, in a two-step etching processes, GaN nanowires are formed only in metal uncovered regions, and GaN regions with metal-covering show nano-porous sidewalls. We propose that nanowires and porous nanostructures are tuned by sufficient and limited etch rate, respectively. PL spectra shows a red-shift of band edge emission in GaN nanostructures. The formation mechanism of nanowires was illustrated by two separated electrochemical reactions occur simultaneously. The function of metals and UV light was illustrated by the scheme of potential relationship between energy bands in Si, GaN and standard hydrogen electrode potential of solution and metals.

  4. Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization.

    PubMed

    Van Well, Tyler L; Redshaw, Matthew; Gamage, Nadeesha D; Kandegedara, R M Eranjan B

    2016-01-01

    A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications. PMID:27500824

  5. Nanopore detection of double stranded DNA using a track-etched polycarbonate membrane.

    PubMed

    Kececi, Kaan; San, Nevim; Kaya, Dila

    2015-11-01

    We investigate the resistive-pulse sensing of 50-bp DNA using track-etched polycarbonate (PC) nanopores and show the translocation dynamics originating from the electrophoretic transport of DNAs. Conically shaped PC nanopore membranes have been prepared with asymmetric chemical etching technique. We show the potential and concentration dependence of DNA translocation through a PC nanopore. We find that the translocation of DNA scales linearly with both potential and concentration. Additionally, the threshold potential is determined to complete the translocation. Finally, by investigating the current-pulse amplitudes of nanopores with different tip sizes, we show that the nanopore size can be successfully used to distinguish the DNA molecules. These results suggest great promise for the sensing of short DNAs and understanding the dynamics of the translocation process using chemically-etched PC nanopores.

  6. Advanced antireflective nanostructures etched down from nanosilver colloid-transformed island mask

    NASA Astrophysics Data System (ADS)

    Park, Seong-Je; Kim, Chul-Hyun; Lee, Ji-Hye; Jeong, Jun-Ho; Lee, Eung-Sug; Choi, Jun-Hyuk

    2012-11-01

    Advanced fabrication methods for antireflective nanostructures are presented via the formation of thermally grown nanosilver islands from continuously deposited colloidal multilayers, followed by a multi-step reactive ion etch (RIE) with optimized gas mixture rate. This process allows the formation of a random array of nanostructures of diameter 150 nm or less and height greater than 200 nm. The reflectance falls to around 0.7% in the visible region, with reasonably enhanced broadband stability and reduced incidence angle dependence. The tunability of antireflection was investigated with respect to several parameters associated with the nanosilver etch mask fabrication and RIE conditions.

  7. Parametric study of compound semiconductor etching utilizing inductively coupled plasma source

    SciTech Connect

    Constantine, C.; Johnson, D.; Barratt, C.

    1996-07-01

    Inductively Coupled Plasma (ICP) sources are extremely promising for large-area, high-ion density etching or deposition processes. In this review the authors compare results for GaAs and GaN etching with both ICP and Electron Cyclotron Resonance (ECR) sources on the same single-wafer platform. The ICP is shown to be capable of very high rates with excellent anisotropy for fabrication of GaAs vias or deep mesas in GaAs or GaN waveguide structures.

  8. Dynamic selective etching: a facile route to parabolic optical fiber nano-probe.

    PubMed

    Zhu, Wei; Shi, Tielin; Tang, Zirong; Gong, Bo; Liao, Guanglan; Tully, John

    2013-03-25

    A dynamic etching approach is proposed through the appropriate variation of etchant composition ratio during the etching process, resulting in the parabolic shape of optical fiber nano-probe with a favorable changing of cone angle. The probe formation mechanism is thoroughly analyzed to illustrate the controllability and simplicity of this method. Optical properties of as-made probes are simulated and experimentally characterized and compared with the linear shape probes of different cone angles. It shows that the parabolic shape probes are superior to the linear shape ones with respect to the transmission efficiency and light focusing capability.

  9. Water adsorption on etched hydrophobic surfaces of L-, D- and DL-valine crystals

    NASA Astrophysics Data System (ADS)

    Segura, J. J.; Verdaguer, A.; Fraxedas, J.

    2014-03-01

    The adsorption of water on etched (001) surfaces of L-, D- and DL-valine crystals has been characterized by atomic force microscopy (AFM) using different operational modes (contact, non-contact and electrostatic) above and below the dew point, the temperature at which water vapor from humid air condenses into liquid water at constant atmospheric pressure. The analysis of the images suggests the formation of aggregates of solvated valine molecules that easily diffuse on the hydrophobic terraces only constrained by step barriers of the well-defined chiral parallelepipedic patterns induced by the etching process.

  10. Bond strength between resin composite and etched and non-etched glass ionomer.

    PubMed

    Zanata, R L; Navarro, M F; Ishikiriama, A; da Silva e Souza Júnior, M H; Delazari, R C

    1997-01-01

    The authors evaluated, in vitro, the effects of etching glass ionomer cements prior to the application of a bonding agent and a resin composite on the bond strength of the glass ionomer/resin composite interface. Six glass ionomer cements were tested using the same bonding agent/resin composite system (Scotchbond Multipurpose/Z 100). For each material, 16 specimens were prepared and divided into two groups. Eight of the specimens were not etched while eight were etched with 37% phosphoric acid for 15 seconds. All the materials were used according to the manufacturers' instructions. Glass ionomer cylinders were prepared and were mounted in an assembly apparatus and the bonding agent/resin composite transferred to a demarcated area on the cement surface. The specimens were stored for 24 hours in distilled water at 37 degrees C and thermocycled. After thermocycling, the specimens were placed in a testing machine and a shear load applied with a knife-edged rod at the glass ionomer/resin composite interface. The shear bond strength was calculated and expressed in MPa. Data were analyzed by ANOVA and the Tukey-Kramer test. There were no significant differences among the shear bond strengths of the resin composite to etched and non-etched glass ionomer cements.

  11. Steady-state damage profiles due to reactive ion etching and ion-assisted etching

    SciTech Connect

    Davis, R.J.; Jha, P.

    1995-03-01

    Ion damage of materials due to reactive ion etching and ion-assisted etching is formulated as a dynamic problem involving the etch rate, damage creation due to ions, diffusion, and ion range effects. The differential equation is solved in the steady-state assuming an exponentially decreasing damage creation function. The ratio {ital D}/{ital a}{epsilon}, where {ital D} is the damage coefficient, {ital a} the inherent depth of ion damage, and {epsilon} the etch rate is shown to be an important parameter determining the steady-state damage profile. Results are examined for situations in which the parameter is much less than or much greater than unity, corresponding to range- and diffusion-dominated profiles, respectively. In both situations, steady-state damage profiles will be quite sensitive to the etch rate of the surface. We suggest some experiments which may elucidate the separate contributions of ion channeling and diffusion to observed damage depth profiles. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  12. Operational specifications of the laser illuminated track etch scattering dosemeter reader.

    PubMed

    Moore, M E; Gepford, H J; Hoffman, J M; McKeever, R J; Devine, R T

    2006-01-01

    The personnel dosimetry operations team at the Los Alamos National Laboratory (LANL) has accepted the laser illuminated track etch scattering (LITES) dosemeter reader into its suite of radiation dose measurement instruments. The LITES instrument transmits coherent light from a He-Ne laser through the pertinent track etch foil and a photodiode measures the amount of light scattered by the etched tracks. A small beam stop blocks the main laser light, while a lens refocuses the scattered light into the photodiode. Three stepper motors in the current LITES system are used to position a carousel that holds 36 track etch dosemeters (TEDs). Preliminary work with the LITES system demonstrated the device had a linear response in counting foils subjected to exposures up to 50 mSv (5.0 rem). The United States Department of Energy requires that the annual general employee dose not exceed 50 mSv (5.0 rem). On a regular basis, LANL uses the Autoscan-60 reader system (Thermo Electron Corp.) for counting track etch dosemeters. However, LANL uses a 15 h etch process for CR-39 dosemeters, and this produces more and larger track etch pits than the 6 h etch used by many institutions. Therefore, LANL only uses the Autoscan-60 for measuring neutron dose equivalent up to exposure levels of approximately 3 mSv (300 mrem). The LITES system has a measured lower limit of detection of approximately 0.6 mSv (60 mrem), and it has a correlation coefficient of R (2) = 0.99 over an exposure range up to 500 mSv (50.0 rem). A series of blind studies were done using three methods: the Autoscan-60 system, manual counting by optical microscope and the LITES instrument. A collection of track etch dosemeters of unknown neutron dose equivalent (NDE) were analysed using the three methods, and the performance coefficient (PC) was calculated when the NDE became known. The Autoscan-60 and optical microscope methods had a combined PC = 0.171, and the LITES instrument had a PC = 0.194, where a PC less than or

  13. Fabrication of micro-nano structure nanofibers by solvent etching.

    PubMed

    Min, Minghua; Wang, Xuefen; Yang, Yin; Liu, Zongyuan; Zhou, Zhe; Zhu, Meifang; Chen, Yanmo; Hsiao, Benjamin S

    2011-08-01

    Micro-Nano structure nanofibrous affinity membranes of poly(ether sulfones) (PES) blended with a functional polymer poly(ethyleneimine) (PEI) were fabricated by electrospinning technique followed by solvent etching in crosslinking solution. The surface SEM image of the water washed PES/PEI nanofibrous membrane confirmed that PEI was concentrated on the fiber surface. The nanofibrous PES/PEI membranes were crosslinked in a mixture of acetone and water with glutaraldehyde (crosslinking agent, GA), and the micro-nano structural surface of the nanofibrous membranes was created by solvent etching due to the solvation between PEI and the solvent water in the crosslinking solution during the crosslinking process. The influence of the component of the crosslinking bath on the mophology of the resulting PES/PEI nanofibers was investigated. It was found that the relatively uniform micro-nano spherules grew on the surface of the nanofibers when the content of water in crosslinking solution was more than 20 wt%, and the diameters of the spherules were in the range of 50-250 nm. The advantage of the micro-nano structrue for the heavy metal ions removal in wastwater has been demonstrated by taking a series of static adsorption experiments. It was found that the micro-nano structrue of PES/PEI nanofibrous membranes could bring high performance of adsorption capacity for heavy metal ions, indicating that the unique morphology could bring much more large surface area per unit mass and high effectivity for heavy metal ions removal from aqueous solutions.

  14. HAREM: high aspect ratio etching and metallization for microsystems fabrication

    NASA Astrophysics Data System (ADS)

    Sarajlic, Edin; Yamahata, Christophe; Cordero, Mauricio; Collard, Dominique; Fujita, Hiroyuki

    2008-07-01

    We report a simple bulk micromachining method for the fabrication of high aspect ratio monocrystalline silicon MEMS (microelectromechanical systems) in a standard silicon wafer. We call this two-mask microfabrication process high aspect ratio etching and metallization or HAREM: it combines double-side etching and metallization to create suspended micromechanical structures with electrically 'insulating walls' on their backside. The insulating walls ensure a proper electrical insulation between the different actuation and sensing elements situated on either fixed or movable parts of the device. To demonstrate the high potential of this simple microfabrication method, we have designed and characterized electrostatically actuated microtweezers that integrate a differential capacitive sensor. The prototype showed an electrical insulation better than 1 GΩ between the different elements of the device. Furthermore, using a lock-in amplifier circuit, we could measure the position of the moving probe with few nanometers resolution for a displacement range of about 3 µm. This work was presented in part at the 21st IEEE MEMS Conference (Tucson, AZ, USA, 13-17 January, 2008) (doi:10.1109/MEMSYS.2008.4443656).

  15. SEMICONDUCTOR DEVICES: Above 700 V superjunction MOSFETs fabricated by deep trench etching and epitaxial growth

    NASA Astrophysics Data System (ADS)

    Zehong, Li; Min, Ren; Bo, Zhang; Jun, Ma; Tao, Hu; Shuai, Zhang; Fei, Wang; Jian, Chen

    2010-08-01

    Silicon superjunction power MOSFETs were fabricated with deep trench etching and epitaxial growth, based on the process platform of the Shanghai Hua Hong NEC Electronics Company Limited. The breakdown voltages of the fabricated superjunction MOSFETs are above 700 V and agree with the simulation. The dynamic characteristics, especially reverse diode characteristics, are equivalent or even superior to foreign counterparts.

  16. Selective Etching via Soft Lithography of Conductive Multilayered Gold Films with Analysis of Electrolyte Solutions

    ERIC Educational Resources Information Center

    Gerber, Ralph W.; Oliver-Hoyo, Maria T.

    2008-01-01

    This experiment is designed to expose undergraduate students to the process of selective etching by using soft lithography and the resulting electrical properties of multilayered films fabricated via self-assembly of gold nanoparticles. Students fabricate a conductive film of gold on glass, apply a patterned resist using a polydimethylsiloxane…

  17. NiCr etching in a reactive gas

    SciTech Connect

    Ritter, J.; Boucher, R.; Morgenroth, W.; Meyer, H. G.

    2007-05-15

    The authors have etched NiCr through a resist mask using Cl/Ar based chemistry in an electron cyclotron resonance etch system. The optimum gas mixture and etch parameters were found for various ratios of Ni to Cr, based on the etch rate, redeposits, and the etch ratio to the mask. The introduction of O{sub 2} into the chamber, which is often used in the etching of Cr, served to both increase and decrease the etch rate depending explicitly on the etching parameters. Etch rates of >50 nm min{sup -1} and ratios of >1 (NiCr:Mask) were achieved for NiCr (80:20). Pattern transfer from the mask into the NiCr was achieved with a high fidelity and without redeposits for a Cl/Ar mix of 10% Ar (90% Cl{sub 2}) at an etch rate of {approx_equal}50 nm min{sup -1} and a ratio of 0.42 (NiCr:ZEP 7000 e-beam mask)

  18. Residue-free reactive ion etching of 3C-SiC and 6H-SiC in fluorinated mixture plasmas

    SciTech Connect

    Yih, P.H.; Steckl, A.J.

    1995-08-01

    The authors report on residue-free reactive ion etching (RIE) of 3C-SiC and 6H-SiC in mixtures of fluorinated gases consisting of a primary (CHF{sub 3}) and a secondary gas (CF{sub 4}, NF{sub 3}, and SF{sub 6}). The corresponding etch rate, etched surface morphology, anisotropic profile, and process reproducibility are obtained at different levels of CHF{sub 3}. The advantage of this approach is to eliminate gas additives (H{sub 2} and O{sub 2}) while maintaining the residue-free RIE and high process portability. The effect of SiC doping concentration and dopant type on obtaining residue-free RIE is reported along with the effects of plasma pressure and RF power. Etching mechanisms, plasma chemistry, and optimized etching conditions are also discussed.

  19. CH4/Ar/H2/SF6 Plasma Etching for Surface Oxide Removal of Indium Bumps

    NASA Astrophysics Data System (ADS)

    Huang, Yue; Lin, Chun; Ye, Zhen-Hua; Liao, Qing-Jun; Ding, Rui-Jun

    2015-07-01

    Plasma etching for surface indium oxide removal by methane/argon/hydrogen/sulfur hexafluoride (CH4/Ar/H2/SF6) mixture has been implemented. The morphology of the indium bumps was not deteriorated after the plasma etching. High-resolution O 1 s x-ray photoelectron spectroscopy (XPS) proved that the In-O component decreased from 44.5% for the nonetched sample to 10.8% for the sample after plasma etching. The surface modification of the indium bumps might be in the form of doped fluorine according to the XPS results. The zero-bias resistance derived from current-voltage ( I- V) measurements for plasma-etched infrared detectors was comparable to that for nonetched ones, indicating that such plasma treatment is suitable for processing sensitive materials such as mercury cadmium telluride.

  20. Electrolytic Transport Through Cylindrical Etched Pores in Polyethylene Terepthalate Track-Etched Membrane

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjeev; Chakarvarti, S. K.

    In the present work, electrolytic transport phenomena is studied for different electrolytes (LiCl, NaCl, KCl of different concentrations) at room temperature (25 ± 2°C) through etched pores with different diameters having cylindrical shape in track-etched membranes of polyethylene terepthalate (PET) with pore density of the order of 106/cm2. Electric potential has been used as the driving force. It has been observed that electrolytic transport through pores is different for different electrolytes, depending strongly on size of cations and is independent of size of anions. In the case of cylindrical pores, there has not been found appreciable change in forward and backward resistances.