Plasma & reactive ion etching to prepare ohmic contacts

DOEpatents

Gessert, Timothy A.

2002-01-01

A method of making a low-resistance electrical contact between a metal and a layer of p-type CdTe surface by plasma etching and reactive ion etching comprising: a) placing a CdS/CdTe layer into a chamber and evacuating said chamber; b) backfilling the chamber with Argon or a reactive gas to a pressure sufficient for plasma ignition; and c) generating plasma ignition by energizing a cathode which is connected to a power supply to enable the plasma to interact argon ions alone or in the presence of a radio-frequency DC self-bias voltage with the p-CdTe surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin Yunpeng; Sawin, Herbert H.

The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ionmore » scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.« less

Molecular dynamic simulation study of plasma etching L10 FePt media in embedded mask patterning (EMP) process

NASA Astrophysics Data System (ADS)

Zhu, Jianxin; Quarterman, P.; Wang, Jian-Ping

2017-05-01

Plasma etching process of single-crystal L10-FePt media [H. Wang et al., Appl. Phys. Lett. 102(5) (2013)] is studied using molecular dynamic simulation. Embedded-Atom Method [M. S. Daw and M. I. Baskes, Phy. Rev. B 29, 6443 (1984); X. W. Zhou, R. A. Johnson and H. N. G. Wadley, Phy. Rev. B 69, 144113 (2004)] is used to calculate the interatomic potential within atoms in FePt alloy, and ZBL potential [J.F. Ziegler, J. P. Biersack and U. Littmark, "The Stopping and Range of Ions in Matter," Volume 1, Pergamon,1985] in comparison with conventional Lennard-Jones "12-6" potential is applied to interactions between etching gas ions and metal atoms. It is shown the post-etch structure defects can include amorphized surface layer and lattice interstitial point defects that caused by etchant ions passed through the surface layer. We show that the amorphized or damaged FePt lattice surface layer (or "magnetic dead-layer") thickness after etching increases with ion energy for Ar ion impacts, but significantly small for He ions at up to 250eV ion energy. However, we showed that He sputtering creates more interstitial defects at lower energy levels and defects are deeper below the surface compared to Ar sputtering. We also calculate the interstitial defect level and depth as dependence on ion energy for both Ar and He ions. Media magnetic property loss due to these defects is also discussed.

A new concept for spatially divided Deep Reactive Ion Etching with ALD-based passivation

NASA Astrophysics Data System (ADS)

Roozeboom, F.; Kniknie, B.; Lankhorst, A. M.; Winands, G.; Knaapen, R.; Smets, M.; Poodt, P.; Dingemans, G.; Keuning, W.; Kessels, W. M. M.

2012-12-01

Conventional Deep Reactive Ion Etching (DRIE) is a plasma etch process with alternating half-cycles of 1) Si-etching with SF6 to form gaseous SiFx etch products, and 2) passivation with C4F8 that polymerizes as a protecting fluorocarbon deposit on the sidewalls and bottom of the etched features. In this work we report on a novel alternative and disruptive technology concept of Spatially-divided Deep Reactive Ion Etching, S-DRIE, where the process is converted from the time-divided into the spatially divided regime. The spatial division can be accomplished by inert gas bearing 'curtains' of heights down to ~20 μm. These curtains confine the reactive gases to individual (often linear) injection slots constructed in a gas injector head. By horizontally moving the substrate back and forth under the head one can realize the alternate exposures to the overall cycle. A second improvement in the spatially divided approach is the replacement of the CVD-based C4F8 passivation steps by ALD-based oxide (e.g. SiO2) deposition cycles. The method can have industrial potential in cost-effective creation of advanced 3D interconnects (TSVs), MEMS manufacturing and advanced patterning, e.g., in nanoscale transistor line edge roughness using Atomic Layer Etching.

Ion-enhanced chemical etching of ZrO2 in a chlorine discharge

NASA Astrophysics Data System (ADS)

Sha, Lin; Cho, Byeong-Ok; Chang, Jane P.

2002-09-01

Chlorine plasma is found to chemically etch ZrO2 thin films in an electron cyclotron resonance reactor, and the etch rate scaled linearly with the square root of ion energy at high ion energies with a threshold energy between 12-20 eV. The etching rate decreased monotonically with increasing chamber pressures, which corresponds to reduced electron temperatures. Optical emission spectroscopy and quadrupole mass spectrometry were used to identify the reaction etching products. No Zr, O, or ZrCl were detected as etching products, but highly chlorinated zirconium compounds (ZrCl2, ZrCl3, and ZrCl4) and ClO were found to be the dominant etching products. ZrCl3 was the dominant etching products at low ion energies, while ZrCl4 became dominant at higher ion energies. This is consistent with greater momentum transfer and enhanced surface chlorination, as determined by x-ray photoelectron spectroscopy, at increased ion energies. Several ion-enhanced chemical reactions are proposed to contribute to the ZrO2 etching. copyright 2002 American Vacuum Society.

Ion beam sputter etching and deposition of fluoropolymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

1978-01-01

Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

Differentiation of grain orientation with corrosive and colour etching on a granular bainitic steel.

PubMed

Reisinger, S; Ressel, G; Eck, S; Marsoner, S

2017-08-01

This study presents a detailed verification of the etching methods with Nital and Klemm on a granular bainitic steel. It is shown that both methods allow the identification of the crystal orientation, whereas Klemm etching enables also a quantification of the apparent phases, as also retained austenite can be distinguished from the other bainitic microstructures. A combination of atom probe tomography with electron-back-scattered-diffraction showed that both etching methods emphasize the bainitic {100} crystal orientation. However, a cross-section produced by focused ion beam evidenced that Klemm etching leads to the formation of a topography of the different oriented bainitic crystals that directly affects the thickness and therefore the apparent colour of the deposited layer formed during etching. Copyright © 2017 Elsevier Ltd. All rights reserved.

Components, Assembly and Electrochemical Properties of Three-Dimensional Battery Architectures

DTIC Science & Technology

2016-03-01

batteries is directed at our project on 3-D lithium - ion batteries where improvements in materials and fabrication methods are expected to facilitate...reporting period, we focused on new materials and electrode array fabrication processes for 3-D lithium - ion batteries and made substantial progress. In...to facilitate the assembly of a full 3-D lithium - ion battery system. a Pattern silicon dioxide etch I I I I I mask b DRIE etch silicon posts c I I

Recovery of GaN surface after reactive ion etching

NASA Astrophysics Data System (ADS)

Fan, Qian; Chevtchenko, S.; Ni, Xianfeng; Cho, Sang-Jun; Morko, Hadis

2006-02-01

Surface properties of GaN subjected to reactive ion etching and the impact on device performance have been investigated by surface potential, optical and electrical measurements. Different etching conditions were studied and essentially high power levels and low chamber pressures resulted in higher etch rates accompanying with the roughening of the surface morphology. Surface potential for the as-grown c-plane GaN was found to be in the range of 0.5~0.7 V using Scanning Kevin Probe Microscopy. However, after reactive ion etching at a power level of 300 W, it decreased to 0.1~0.2 V. A nearly linear reduction was observed on c-plane GaN with increasing power. The nonpolar a-plane GaN samples also showed large surface band bending before and after etching. Additionally, the intensity of the near band-edge photoluminescence decreased and the free carrier density increased after etching. These results suggest that the changes in the surface potential may originate from the formation of possible nitrogen vacancies and other surface oriented defects and adsorbates. To recover the etched surface, N II plasma, rapid thermal annealing, and etching in wet KOH were performed. For each of these methods, the surface potential was found to increase by 0.1~0.3 V, also the reverse leakage current in Schottky diodes fabricated on treated samples was reduced considerably compared with as-etched samples, which implies a partial-to-complete recovery from the plasma-induced damage.

Ion beam sputtering of fluoropolymers

NASA Technical Reports Server (NTRS)

Sovey, J. S.

1978-01-01

Etching and deposition of fluoropolymers are of considerable industrial interest for applications dealing with adhesion, chemical inertness, hydrophobicity, and dielectric properties. This paper describes ion beam sputter processing rates as well as pertinent characteristics of etched targets and films. 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. Also presented are sputter target and film characteristics which were documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs.

Ion transport by gating voltage to nanopores produced via metal-assisted chemical etching method

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Inomata, Naoki; Toda, Masaya; Ono, Takahito

2018-05-01

In this work, we report a simple and low-cost way to create nanopores that can be employed for various applications in nanofluidics. Nano sized Ag particles in the range from 1 to 20 nm are formed on a silicon substrate with a de-wetting method. Then the silicon nanopores with an approximate 15 nm average diameter and 200 μm height are successfully produced by the metal-assisted chemical etching method. In addition, electrically driven ion transport in the nanopores is demonstrated for nanofluidic applications. Ion transport through the nanopores is observed and could be controlled by an application of a gating voltage to the nanopores.

Ion transport by gating voltage to nanopores produced via metal-assisted chemical etching method.

PubMed

Van Toan, Nguyen; Inomata, Naoki; Toda, Masaya; Ono, Takahito

2018-05-11

In this work, we report a simple and low-cost way to create nanopores that can be employed for various applications in nanofluidics. Nano sized Ag particles in the range from 1 to 20 nm are formed on a silicon substrate with a de-wetting method. Then the silicon nanopores with an approximate 15 nm average diameter and 200 μm height are successfully produced by the metal-assisted chemical etching method. In addition, electrically driven ion transport in the nanopores is demonstrated for nanofluidic applications. Ion transport through the nanopores is observed and could be controlled by an application of a gating voltage to the nanopores.

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.

Effect of helium ion beam treatment on wet etching of silicon dioxide

NASA Astrophysics Data System (ADS)

Petrov, Yu. V.; Grigoryev, E. A.; Sharov, T. V.; Baraban, A. P.

2018-03-01

We investigated the effect of helium ion beam treatment on the etching rate of silicon dioxide in a water based solution of hydrofluoric acid. A 460-nm-thick silicon dioxide film on silicon was irradiated with helium ions having energies of 20 keV and 30 keV with ion fluences ranging from 1014 cm-2 to 1017 cm-2. The dependence of the etching rate on depth was obtained and compared with the depth distribution of ion-induced defects, which was obtained from numerical simulation. Irradiation with helium ions results in an increase of the etching rate of silicon dioxide. The dependence of the etching rate on the calculated concentration of ion-induced defects is described.

Methods for globally treating silica optics to reduce optical damage

DOEpatents

Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie

2012-11-20

A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.

Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

PubMed

Weinreich, Wenke; Acker, Jörg; Gräber, Iris

2007-03-30

In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control.

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, D.C.; Tepermeister, I.; Sawin, H.H.

A multiple beam apparatus has been constructed to facilitate the study of ion-enhanced fluorine chemistry on undoped polysilicon and silicon dioxide surfaces by allowing the fluxes of fluorine (F) atoms and argon (Ar{sup +}) ions to be independently varied over several orders of magnitude. The chemical nature of the etching surfaces has been investigated following the vacuum transfer of the sample dies to an adjoining x-ray photoelectron spectroscopy facility. The etching {open_quotes}enhancement{close_quotes} effect of normally incident Ar{sup +} ions has been quantified over a wide range of ion energy through the use of Kaufman and electron cyclotron resonance-type ion sources.more » The increase in per ion etching yield of fluorine saturated silicon and silicon dioxide surfaces with increasing ion energy (E{sub ion}) was found to scale as (E{sub ion}{sup 1/2}-E{sub th}{sup 1/2}), where E{sub th} is the etching threshold energy for the process. Simple near-surface site occupation models have been proposed for the quantification of the ion-enhanced etching kinetics in these systems. Acceptable agreement has been found in comparison of these Ar{sup +}/F etching model predictions with similar Ar{sup +}/XeF{sub 2} studies reported in the literature, as well as with etching rate measurements made in F-based plasmas of gases such as SF{sub 6} and NF{sub 3}. 69 refs., 12 figs., 6 tabs.« less

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.

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.

Dynamic secondary ion mass spectroscopy of Au nanoparticles on Si wafer using Bi3+ as primary ion coupled with surface etching by Ar cluster ion beam: The effect of etching conditions on surface structure

NASA Astrophysics Data System (ADS)

Park, Eun Ji; Choi, Chang Min; Kim, Il Hee; Kim, Jung-Hwan; Lee, Gaehang; Jin, Jong Sung; Ganteför, Gerd; Kim, Young Dok; Choi, Myoung Choul

2018-01-01

Wet-chemically synthesized Au nanoparticles were deposited on Si wafer surfaces, and the secondary ions mass spectra (SIMS) from these samples were collected using Bi3+ with an energy of 30 keV as the primary ions. In the SIMS, Au cluster cations with a well-known, even-odd alteration pattern in the signal intensity were observed. We also performed depth profile SIMS analyses, i.e., etching the surface using an Ar gas cluster ion beam (GCIB), and a subsequent Bi3+ SIMS analysis was repetitively performed. Here, two different etching conditions (Ar1600 clusters of 10 keV energy or Ar1000 of 2.5 keV denoted as "harsh" or "soft" etching conditions, respectively) were used. Etching under harsh conditions induced emission of the Au-Si binary cluster cations in the SIMS spectra of the Bi3+ primary ions. The formation of binary cluster cations can be induced by either fragmentation of Au nanoparticles or alloying of Au and Si, increasing Au-Si coordination on the sample surface during harsh GCIB etching. Alternatively, use of the soft GCIB etching conditions resulted in exclusive emission of pure Au cluster cations with nearly no Au-Si cluster cation formation. Depth profile analyses of the Bi3+ SIMS combined with soft GCIB etching can be useful for studying the chemical environments of atoms at the surface without altering the original interface structure during etching.

METHOD OF APPLYING COPPER COATINGS TO URANIUM

DOEpatents

Gray, A.G.

1959-07-14

A method is presented for protecting metallic uranium, which comprises anodic etching of the uranium in an aqueous phosphoric acid solution containing chloride ions, cleaning the etched uranium in aqueous nitric acid solution, promptly electro-plating the cleaned uranium in a copper electro-plating bath, and then electro-plating thereupon lead, tin, zinc, cadmium, chromium or nickel from an aqueous electro-plating bath.

IRON COATED URANIUM AND ITS PRODUCTION

DOEpatents

Gray, A.G.

1960-03-15

A method of applying a protective coating to a metallic uranium article is given. The method comprises etching the surface of the article with an etchant solution containlng chloride ions, such as a solution of phosphoric acid and hydrochloric acid, cleaning the etched surface, electroplating iron thereon from a ferrous ammonium sulfate electroplating bath, and soldering an aluminum sheath to the resultant iron layer.

Correlation between surface chemistry and ion energy dependence of the etch yield in multicomponent oxides etching

NASA Astrophysics Data System (ADS)

Bérubé, P.-M.; Poirier, J.-S.; Margot, J.; Stafford, L.; Ndione, P. F.; Chaker, M.; Morandotti, R.

2009-09-01

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 CaxBa(1-x)Nb2O6 (CBN) and SrTiO3 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 Cl2 plasma, it is found that the chlorine uptake is inhibiting the etching reaction, with the desorption of nonvolatile NbCl2 and BaCl2 compounds being the rate-limiting step.

METHOD OF APPLYING NICKEL COATINGS ON URANIUM

DOEpatents

Gray, A.G.

1959-07-14

A method is presented for protectively coating uranium which comprises etching the uranium in an aqueous etching solution containing chloride ions, electroplating a coating of nickel on the etched uranium and heating the nickel plated uranium by immersion thereof in a molten bath composed of a material selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, and mixtures thereof, maintained at a temperature of between 700 and 800 deg C, for a time sufficient to alloy the nickel and uranium and form an integral protective coating of corrosion-resistant uranium-nickel alloy.

Effect of Metal Ion Etching on the Tribological, Mechanical and Microstructural Properties of TiN-COATED d2 Tool Steel Using Cae Pvd Technique

NASA Astrophysics Data System (ADS)

Ali, Mubarak; Hamzah, Esah Binti; Hj. Mohd Toff, Mohd Radzi

A study has been made on TiN coatings deposited on D2 tool steel substrates by using commercially available cathodic arc evaporation, physical vapor deposition technique. The goal of this work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness, coefficient of friction and surface roughness of TiN coating deposited on tool steel, which is vastly use in tool industry for various applications. A pin-on-disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating at various ion etching rates. The tribo-test showed that the minimum value recorded for friction coefficient was 0.386 and 0.472 with standard deviation of 0.056 and 0.036 for the coatings deposited at zero and 16 min ion etching. The differences in friction coefficient and surface roughness was mainly associated with the macrodroplets, which was produced during etching stage. The coating deposited for 16 min metal ion etching showed the maximum hardness, i.e., about five times higher than uncoated one and 1.24 times to the coating deposited at zero ion etching. After friction test, the wear track was observed by using field emission scanning electron microscope. The coating deposited for zero ion etching showed small amounts of macrodroplets as compared to the coating deposited for 16 min ion etching. The elemental composition on the wear scar were investigated by means of energy dispersive X-ray, indicate no further TiN coating on wear track. A considerable improvement in TiN coatings was recorded as a function of various ion etching rates.

Die singulation method

DOEpatents

Swiler, Thomas P.; Garcia, Ernest J.; Francis, Kathryn M.

2013-06-11

A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with an HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

Die singulation method

DOEpatents

Swiler, Thomas P [Albuquerque, NM; Garcia, Ernest J [Albuquerque, NM; Francis, Kathryn M [Rio Rancho, NM

2014-01-07

A method is disclosed for singulating die from a semiconductor substrate (e.g. a semiconductor-on-insulator substrate or a bulk silicon substrate) containing an oxide layer (e.g. silicon dioxide or a silicate glass) and one or more semiconductor layers (e.g. monocrystalline or polycrystalline silicon) located above the oxide layer. The method etches trenches through the substrate and through each semiconductor layer about the die being singulated, with the trenches being offset from each other around at least a part of the die so that the oxide layer between the trenches holds the substrate and die together. The trenches can be anisotropically etched using a Deep Reactive Ion Etching (DRIE) process. After the trenches are etched, the oxide layer between the trenches can be etched away with a HF etchant to singulate the die. A release fixture can be located near one side of the substrate to receive the singulated die.

New frontiers of atomic layer etching

NASA Astrophysics Data System (ADS)

Sherpa, Sonam D.; Ranjan, Alok

2018-03-01

Interest in atomic layer etching (ALE) has surged recently because it offers several advantages over continuous or quasicontinuous plasma etching. These benefits include (1) independent control of ion energy, ion flux, and radical flux, (2) flux-independent etch rate that mitigates the iso-dense loading effects, and (3) ability to control the etch rate with atomic or nanoscale precision. In addition to these benefits, we demonstrate an area-selective etching for maskless lithography as a new frontier of ALE. In this paper, area-selective etching refers to the confinement of etching into the specific areas of the substrate. The concept of area-selective etching originated during our studies on quasi-ALE of silicon nitride which consists of sequential exposure of silicon nitride to hydrogen and fluorinated plasma. The findings of our studies reported in this paper suggest that it may be possible to confine the etching into specific areas of silicon nitride without using any mask by replacing conventional hydrogen plasma with a localized source of hydrogen ions.

Characterizing fluorocarbon assisted atomic layer etching of Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

NASA Astrophysics Data System (ADS)

Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

2017-02-01

With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C4F8 and CHF3) and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J. Vac. Sci. Technol., A 32, 020603 (2014) and D. Metzler et al., J. Vac. Sci. Technol., A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO2 and Si but is limited with regard to control over material etching selectivity. Ion energy over the 20-30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF3 has a lower FC deposition yield for both SiO2 and Si and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F8. The thickness of deposited FC layers using CHF3 is found to be greater for Si than for SiO2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen whereas the chemical state of the substrate varies much less. On the other hand, for FC film deposition of 5 Å for each cycle, strong substrate surface chemical changes are seen during an etching cycle. The nature of this cyclic etching with periodic deposition of thin FC films differs significantly from conventional etching with steady-state FC layers since surface conditions change strongly throughout each cycle.

Uniform lateral etching of tungsten in deep trenches utilizing reaction-limited NF3 plasma process

NASA Astrophysics Data System (ADS)

Kofuji, Naoyuki; Mori, Masahito; Nishida, Toshiaki

2017-06-01

The reaction-limited etching of tungsten (W) with NF3 plasma was performed in an attempt to achieve the uniform lateral etching of W in a deep trench, a capability required by manufacturing processes for three-dimensional NAND flash memory. Reaction-limited etching was found to be possible at high pressures without ion irradiation. An almost constant etching rate that showed no dependence on NF3 pressure was obtained. The effect of varying the wafer temperature was also examined. A higher wafer temperature reduced the threshold pressure for reaction-limited etching and also increased the etching rate in the reaction-limited region. Therefore, the control of the wafer temperature is crucial to controlling the etching amount by this method. We found that the uniform lateral etching of W was possible even in a deep trench where the F radical concentration was low.

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.

Analysis of GaN Damage Induced by Cl2/SiCl4/Ar Plasma

NASA Astrophysics Data System (ADS)

Minami, Masaki; Tomiya, Shigetaka; Ishikawa, Kenji; Matsumoto, Ryosuke; Chen, Shang; Fukasawa, Masanaga; Uesawa, Fumikatsu; Sekine, Makoto; Hori, Masaru; Tatsumi, Tetsuya

2011-08-01

GaN-based optical devices are fabricated using a GaN/InGaN/GaN sandwiched structure. The effect of radicals, ions, and UV light on the GaN optical properties during Cl2/SiCl4/Ar plasma etching was evaluated using photoluminescence (PL) analysis. The samples were exposed to plasma (radicals, ions, and UV light) using an inductively coupled plasma (ICP) etching system and a plasma ion beam apparatus that can separate the effects of UV and ions both with and without covering the SiO2 window on the surface. Etching damage in an InGaN single quantum well (SQW) was formed by exposing the sample to plasma. The damage, which decreases PL emission intensity, was generated not only by ion beam irradiation but also by UV light irradiation. PL intensity decreased when the thickness of the upper GaN layer was etched to less than 60 nm. In addition, simultaneous irradiation of UV light and ions slightly increased the degree of damage. There seems to be a synergistic effect between the UV light and the ions. For high-quality GaN-based optoelectronics and power devices, UV light must be controlled during etching processes in addition to the etching profile, selectivity, and ion bombardment damage.

The thickness correction of sol-gel coating using ion-beam etching in the preparation of antireflection coating

NASA Astrophysics Data System (ADS)

Dong, Siyu; Xie, Lingyun; He, Tao; Jiao, Hongfei; Bao, Ganghua; Zhang, Jinlong; Wang, Zhanshan; Cheng, Xinbin

2017-09-01

For the sol-gel method, it is still challenging to achieve excellent spectral performance when preparing antireflection (AR) coating by this way. The difficulty lies in controlling the film thickness accurately. To correct the thickness error of sol-gel coating, a hybrid approach that combined conventional sol-gel process with ion-beam etching technology was proposed in this work. The etching rate was carefully adjusted and calibrated to a relatively low value for removing the redundant material. Using atomic force microscope (AFM), it has been demonstrated that film surface morphology will not be changed in this process. After correcting the thickness error, an AR coating working at 1064 nm was prepared with transmittance higher than 99.5%.

A flexible method for the preparation of thin film samples for in situ TEM characterization combining shadow-FIB milling and electron-beam-assisted etching.

PubMed

Liebig, J P; Göken, M; Richter, G; Mačković, M; Przybilla, T; Spiecker, E; Pierron, O N; Merle, B

2016-12-01

A new method for the preparation of freestanding thin film samples for mechanical testing in transmission electron microscopes is presented. It is based on a combination of focused ion beam (FIB) milling and electron-beam-assisted etching with xenon difluoride (XeF 2 ) precursor gas. The use of the FIB allows for the target preparation of microstructural defects and enables well-defined sample geometries which can be easily adapted in order to meet the requirements of various testing setups. In contrast to existing FIB-based preparation approaches, the area of interest is never exposed to ion beam irradiation which preserves a pristine microstructure. The method can be applied to a wide range of thin film material systems compatible with XeF 2 etching. Its feasibility is demonstrated for gold and alloyed copper thin films and its practical application is discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Method of manufacture of atomically thin boron nitride

DOEpatents

Zettl, Alexander K

2013-08-06

The present invention provides a method of fabricating at least one single layer hexagonal boron nitride (h-BN). In an exemplary embodiment, the method includes (1) suspending at least one multilayer boron nitride across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure. The present invention also provides a method of fabricating single layer hexagonal boron nitride. In an exemplary embodiment, the method includes (1) providing multilayer boron nitride suspended across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure.

Focused-ion-beam-inflicted surface amorphization and gallium implantation--new insights and removal by focused-electron-beam-induced etching.

PubMed

Roediger, P; Wanzenboeck, H D; Waid, S; Hochleitner, G; Bertagnolli, E

2011-06-10

Recently focused-electron-beam-induced etching of silicon using molecular chlorine (Cl(2)-FEBIE) has been developed as a reliable and reproducible process capable of damage-free, maskless and resistless removal of silicon. As any electron-beam-induced processing is considered non-destructive and implantation-free due to the absence of ion bombardment this approach is also a potential method for removing focused-ion-beam (FIB)-inflicted crystal damage and ion implantation. We show that Cl(2)-FEBIE is capable of removing FIB-induced amorphization and gallium ion implantation after processing of surfaces with a focused ion beam. TEM analysis proves that the method Cl(2)-FEBIE is non-destructive and therefore retains crystallinity. It is shown that Cl(2)-FEBIE of amorphous silicon when compared to crystalline silicon can be up to 25 times faster, depending on the degree of amorphization. Also, using this method it has become possible for the first time to directly investigate damage caused by FIB exposure in a top-down view utilizing a localized chemical reaction, i.e. without the need for TEM sample preparation. We show that gallium fluences above 4 × 10(15) cm(-2) result in altered material resulting from FIB-induced processes down to a depth of ∼ 250 nm. With increasing gallium fluences, due to a significant gallium concentration close beneath the surface, removal of the topmost layer by Cl(2)-FEBIE becomes difficult, indicating that gallium serves as an etch stop for Cl(2)-FEBIE.

Resistless lithography - selective etching of silicon with gallium doping regions

NASA Astrophysics Data System (ADS)

Abdullaev, D.; Milovanov, R.; Zubov, D.

2016-12-01

This paper presents the results for used of resistless lithography with a further reactive-ion etching (RIE) in various chemistry after local (Ga+) implantation of silicon with different doping dose and different size doped regions. We describe the different etching regimes for pattern transfer of FIB implanted Ga masks in silicon. The paper studied the influence of the implantation dose on the silicon surface, the masking effect and the mask resistance to erosion at dry etching. Based on these results we conclude about the possibility of using this method to create micro-and nanoscale silicon structures.

Effect of carbonated water manufactured by a soda carbonator on etched or sealed enamel

PubMed Central

Ryu, Hyo-kyung; Kim, Yong-do; Heo, Sung-su

2018-01-01

Objective The purpose of this study was to determine the effects of carbonated water on etched or sealed enamel according to the carbonation level and the presence of calcium ions. Methods Carbonated water with different carbonation levels was manufactured by a soda carbonator. Seventy-five premolar teeth were randomly divided into a control group and 4 experimental groups in accordance with the carbonation level and the presence of calcium ions in the test solutions. After specimen preparation of the Unexposed, Etched, and Sealed enamel subgroups, all the specimens were submerged in each test solution for 15 minutes three times a day during 7 days. Microhardness tests on the Unexposed and Etched enamel subgroups were performed with 10 specimens from each group. Scanning electron microscopy (SEM) tests on the Unexposed, Etched, and Sealed enamel subgroups were performed with 5 specimens from each group. Microhardness changes in different groups were statistically compared using paired t-tests, the Wilcoxon signed rank test, and the Kruskal-Wallis test. Results The microhardness changes were significantly different between the groups (p = 0.000). The microhardness changes in all experimental groups except Group 3 (low-level carbonated water with calcium ions) were significantly greater than those in the Control group. SEM showed that etched areas of the specimen were affected by carbonated water and the magnitude of destruction varied between groups. Adhesive material was partially removed in groups exposed to carbonated water. Conclusions Carbonated water has negative effects on etched or sealed enamel, resulting in decreased microhardness and removal of the adhesive material. PMID:29291188

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzler, Dominik; Li, Chen; Engelmann, Sebastian

With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching (ALE) processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO 2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C 4F 8 and CHF 3), and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J Vac Sci Technol A 32,more » 020603 (2014), and D. Metzler et al., J Vac Sci Technol A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO 2 and Si, but is limited with regard to control over material etching selectivity. Ion energy over the 20 to 30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF 3 has a lower FC deposition yield for both SiO 2 and Si, and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F 8. The thickness of deposited FC layers using CHF 3 is found to be greater for Si than for SiO 2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen whereas the chemical state of the substrate varies much less. On the other hand, for FC film deposition of 5 Å for each cycle, strong substrate surface chemical changes are seen during an etching cycle. The nature of this cyclic etching with periodic deposition of thin FC films differs significantly from conventional etching with steady-state FC layers since surface conditions change strongly throughout each cycle.« less

Ion track etching revisited: II. Electronic properties of aged tracks in polymers

NASA Astrophysics Data System (ADS)

Fink, D.; Muñoz Hernández, G.; Cruz, S. A.; Garcia-Arellano, H.; Vacik, J.; Hnatowicz, V.; Kiv, A.; Alfonta, L.

2018-02-01

We compile here electronic ion track etching effects, such as capacitive-type currents, current spike emission, phase shift, rectification and background currents that eventually emerge upon application of sinusoidal alternating voltages across thin, aged swift heavy ion-irradiated polymer foils during etching. Both capacitive-type currents and current spike emission occur as long as obstacles still prevent a smooth continuous charge carrier passage across the foils. In the case of sufficiently high applied electric fields, these obstacles are overcome by spike emission. These effects vanish upon etchant breakthrough. Subsequent transmitted currents are usually of Ohmic type, but shortly after breakthrough (during the track' core etching) often still exhibit deviations such as strong positive phase shifts. They stem from very slow charge carrier mobility across the etched ion tracks due to retarding trapping/detrapping processes. Upon etching the track's penumbra, one occasionally observes a split-up into two transmitted current components, one with positive and another one with negative phase shifts. Usually, these phase shifts vanish when bulk etching starts. Current rectification upon track etching is a very frequent phenomenon. Rectification uses to inverse when core etching ends and penumbra etching begins. When the latter ends, rectification largely vanishes. Occasionally, some residual rectification remains which we attribute to the aged polymeric bulk itself. Last not least, we still consider background currents which often emerge transiently during track etching. We could assign them clearly to differences in the electrochemical potential of the liquids on both sides of the etched polymer foils. Transient relaxation effects during the track etching cause their eventually chaotic behaviour.

Fabrication and Theoretical Evaluation of Microlens Arrays on Layered Polymers

NASA Astrophysics Data System (ADS)

Oder, Tom; McMaster, Michael; Merlo, Corey; Bagheri, Camron; Reakes, Clayton; Petrus, Joshua; Li, Dingqiang; Crescimanno, Michael; Andrews, James

2014-03-01

Arrays of microlens were fabricated on nano-layered polymers using reactive ion etching. Semi hemispherical patterns with diameters ranging from 20 to 80 micrometers were first formed on a thick photoresist film that was spin-coated on the layered polymers using standard photolithographic process employing a gray scale glass mask. These patterns were then transferred to the polymers using dry etching in a reactive ion etching system. The optimized etch condition included a mixture of sulfur hexafluoride and oxygen, which resulted in an etch depth of 5 micrometers and successfully exposed the individual sub-micron thick layers in the polymers. Physical characterization of the microlens arrays was done using atomic force microscope and scanning electron microscope. We combine basic physical optics theory with the transfer matrix analysis of optical transport in nano-layered polymers to address subtleties in the chromatic response of microlenses made from these materials. In particular this method explains the len's behavior in and around the reflection band of the materials. We wish to acknowledge support of funds from NSF through its Center for Layered Polymeric Systems (CLiPS) at Case Western Reserve University.

Etching in Chlorine Discharges Using an Integrated Feature Evolution-Plasma Model

NASA Technical Reports Server (NTRS)

Hwang, Helen H.; Bose, Deepak; Govindan, T. R.; Meyyappan, M.; Biegel, Bryan (Technical Monitor)

2001-01-01

Etching of semiconductor materials is reliant on plasma properties. Quantities such as ion and neutral fluxes, both in magnitude and in direction, are often determined by reactor geometry (height, radius, position of the coils, etc.) In order to obtain accurate etching profiles, one must also model the plasma as a whole to obtain local fluxes and distributions. We have developed a set of three models that simulates C12 plasmas for etching of silicon, ion and neutral trajectories in the plasma, and feature profile evolution. We have found that the location of the peak in the ion densities in the reactor plays a major role in determining etching uniformity across the wafer. For a stove top coil inductively coupled plasma (ICP), the ion density is peaked at the top of the reactor. This leads to nearly uniform neutral and ion fluxes across the wafer. A side coil configuration causes the ion density to peak near the sidewalls. Ion fluxes are thus greater toward the wall's and decrease toward the center. In addition, the ions bombard the wafer at a slight angle. This angle is sufficient to cause slanted profiles, which is highly undesirable.

A comparative study of capacitively coupled HBr/He, HBr/Ar plasmas for etching applications: Numerical investigation by fluid model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gul, Banat, E-mail: banatgul@gmail.com; Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp; Aman-ur-Rehman, E-mail: amansadiq@gmail.com

Fluid model has been applied to perform a comparative study of hydrogen bromide (HBr)/He and HBr/Ar capacitively coupled plasma discharges that are being used for anisotropic etching process. This model has been used to identify the most dominant species in HBr based plasmas. Our simulation results show that the neutral species like H and Br, which are the key player in chemical etching, have bell shape distribution, while ions like HBr{sup +}, Br{sup +}, which play a dominant rule in the physical etching, have double humped distribution and show peaks near electrodes. It was found that the dilution of HBrmore » by Ar and/or He results in an increase in electron density and electron temperature, which results in more ionization and dissociation and hence higher densities of neutral and charged species can be achieved. The ratio of positive ion flux to the neutral flux increases with an increase in additive gas fraction. Compare to HBr/He plasma, the HBr/Ar plasma shows a maximum change in the ion density and flux and hence the etching rate can be considered in the ion-assisted and in the ion-flux etch regime in HBr/Ar discharge. The densities of electron and other dominant species in HBr/Ar plasma are higher than those of HBr/He plasma. The densities and fluxes of the active neutrals and positive ions for etching and subsequently chemical etching versus physical sputtering in HBr/Ar and HBr/He plasmas discharge can be controlled by tuning gas mixture ratio and the desire etching can be achieved.« less

Nanowire dopant measurement using secondary ion mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chia, A. C. E.; Boulanger, J. P.; Wood, B. A.

2015-09-21

A method is presented to improve the quantitative determination of dopant concentration in semiconductor nanowire (NW) arrays using secondary ion mass spectrometry (SIMS). SIMS measurements were used to determine Be dopant concentrations in a Be-doped GaAs thin film and NW arrays of various pitches that were dry-etched from the same film. A comparison of these measurements revealed a factor of 3 to 12 difference, depending on the NW array pitch, between the secondary Be ion yields of the film and the NW arrays, despite being identically doped. This was due to matrix effects and ion beam mixing of Be frommore » the NWs into the surrounding benzocyclobutene that was used to fill the space between the NWs. This indicates the need for etched NWs to be used as doping standards instead of 2D films when evaluating NWs of unknown doping by SIMS. Using the etched NWs as doping standards, NW arrays of various pitches grown by the vapour-liquid-solid mechanism were characterized by SIMS to yield valuable insights into doping mechanisms.« less

Characterization and modeling of low energy ion-induced damage in III-V semiconductors

NASA Astrophysics Data System (ADS)

Chen, Ching-Hui

1997-11-01

Low energy ion-induced damage (sub-keV) created during dry etching processes can extend quite deeply into materials. A systematic study on the deep penetration of dry etch-induced damage is necessary to improve device performance and helpful in further understanding the nature of defect propagation in semiconductors. In this study, a phenomenological model of dry etching damage that includes both effects of ion channeling and defect diffusion has been developed. It underscores that in addition to ion channeling, enhanced defect diffusion also plays an important role in establishing the damage profile. Further, the enhanced diffusion of dry etch- induced damage was experimentally observed for the first time by investigating the influences of concurrent above- bandgap laser illumination and low energy Ar+ ion bombardment on the damage profiles of GaAs/AlGaAs and InP-GaAs/InP heterostructures. The results indicate that non-radiative recombination of electron and hole pairs at defect sites is responsible for the observed radiation enhanced diffusion. DLTS measurements are also employed to characterize the nature of the enhanced diffusion in n-GaAs and reveal that a major component of the ion- induced defects is associated with primary point defects. Using the better understanding of the damage propagation in dry etched materials, a thin layer of low temperature grown GaAs (~200A) was utilized to stop defect propagation during dry etching process. This approach has been successfully applied to reduce ion damage that would occur during the formation of a dry-etch gate recess of a high electron mobility transistor. Finally, some future experiments are proposed and conceptually described, which would further clarify some of the many outstanding issues in the understanding and mitigation of etch- induced damage.

Focused Ion Beam Fabrication of Graded Channel Field Effect Transistors (FETs) in GaAs and Si

DTIC Science & Technology

1988-11-21

is used even though the cut may need to be - I-am wide. Since theL ± ne REMOVAL etch time varies as the inverse square of the beam diameter , a ROF...at room temperature a fairly large diameter capillary 1.4-mm and ion induced deposition or etching , the focused ion beam inner diameter was used . For...Pd/B/As/P (alloy sources) Main - micromachining - implantation uses - ion induced deposition - lithography and etching - high resolution SIMS

Industrial ion source technology

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Robinson, R. S.

1979-01-01

In reactive ion etching of Si, varying amounts of O2 were added to the CF4 background. The experimental results indicated an etch rate less than that for Ar up to an O2 partial pressure of about .00006 Torr. Above this O2 pressure, the etch rate with CF4 exceeded that with Ar alone. For comparison the random arrival rate of O2 was approximately equal to the ion arrival rate at a partial pressure of about .00002 Torr. There were also ion source and ion pressure gauge maintenance problems as a result of the use of CF4. Large scale (4 sq cm) texturing of Si was accomplished using both Cu and stainless steel seed. The most effective seeding method for this texturing was to surround the sample with large inclined planes. Designing, fabricating, and testing a 200 sq cm rectangular beam ion source was emphasized. The design current density was 6 mA/sq cm with 500 eV argon ions, although power supply limitations permitted operation to only 2 mA/sq cm. The use of multiple rectangular beam ion sources for continuous processing of wider areas than would be possible with a single source was also studied. In all cases investigated, the most uniform coverage was obtained with 0 to 2 cm beam overlay. The maximum departure from uniform processing at optimum beam overlap was found to be +15%.

Characterizing Fluorocarbon Assisted Atomic Layer Etching of Si Using Cyclic Ar/C 4F 8 and Ar/CHF 3 Plasma

DOE PAGES

Metzler, Dominik; Li, Chen; Engelmann, Sebastian; ...

2016-09-08

With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching (ALE) processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO 2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C 4F 8 and CHF 3), and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J Vac Sci Technol A 32,more » 020603 (2014), and D. Metzler et al., J Vac Sci Technol A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO 2 and Si, but is limited with regard to control over material etching selectivity. Ion energy over the 20 to 30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF 3 has a lower FC deposition yield for both SiO 2 and Si, and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F 8. The thickness of deposited FC layers using CHF 3 is found to be greater for Si than for SiO 2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen whereas the chemical state of the substrate varies much less. On the other hand, for FC film deposition of 5 Å for each cycle, strong substrate surface chemical changes are seen during an etching cycle. The nature of this cyclic etching with periodic deposition of thin FC films differs significantly from conventional etching with steady-state FC layers since surface conditions change strongly throughout each cycle.« less

Surface morphology evolution during plasma etching of silicon: roughening, smoothing and ripple formation

NASA Astrophysics Data System (ADS)

Ono, Kouichi; Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji

2017-10-01

Atomic- or nanometer-scale roughness on feature surfaces has become an important issue to be resolved in the fabrication of nanoscale devices in industry. Moreover, in some cases, smoothing of initially rough surfaces is required for planarization of film surfaces, and controlled surface roughening is required for maskless fabrication of organized nanostructures on surfaces. An understanding, under what conditions plasma etching results in surface roughening and/or smoothing and what are the mechanisms concerned, is of great technological as well as fundamental interest. In this article, we review recent developments in the experimental and numerical study of the formation and evolution of surface roughness (or surface morphology evolution such as roughening, smoothing, and ripple formation) during plasma etching of Si, with emphasis being placed on a deeper understanding of the mechanisms or plasma-surface interactions that are responsible for. Starting with an overview of the experimental and theoretical/numerical aspects concerned, selected relevant mechanisms are illustrated and discussed primarily on the basis of systematic/mechanistic studies of Si etching in Cl-based plasmas, including noise (or stochastic roughening), geometrical shadowing, surface reemission of etchants, micromasking by etch inhibitors, and ion scattering/chanelling. A comparison of experiments (etching and plasma diagnostics) and numerical simulations (Monte Carlo and classical molecular dynamics) indicates a crucial role of the ion scattering or reflection from microscopically roughened feature surfaces on incidence in the evolution of surface roughness (and ripples) during plasma etching; in effect, the smoothing/non-roughening condition is characterized by reduced effects of the ion reflection, and the roughening-smoothing transition results from reduced ion reflections caused by a change in the predominant ion flux due to that in plasma conditions. Smoothing of initially rough surfaces as well as non-roughening of initially planar surfaces during etching (normal ion incidence) and formation of surface ripples by plasma etching (off-normal ion incidence) are also presented and discussed in this context.

Cryogenic Etching of Silicon: An Alternative Method For Fabrication of Vertical Microcantilever Master Molds

PubMed Central

Addae-Mensah, Kweku A.; Retterer, Scott; Opalenik, Susan R.; Thomas, Darrell; Lavrik, Nickolay V.; Wikswo, John P.

2013-01-01

This paper examines the use of deep reactive ion etching (DRIE) of silicon with fluorine high-density plasmas at cryogenic temperatures to produce silicon master molds for vertical microcantilever arrays used for controlling substrate stiffness for culturing living cells. The resultant profiles achieved depend on the rate of deposition and etching of a SiOxFy polymer, which serves as a passivation layer on the sidewalls of the etched structures in relation to areas that have not been passivated with the polymer. We look at how optimal tuning of two parameters, the O2 flow rate and the capacitively coupled plasma (CCP) power, determine the etch profile. All other pertinent parameters are kept constant. We examine the etch profiles produced using e-beam resist as the main etch mask, with holes having diameters of 750 nm, 1 µm, and 2 µm. PMID:24223478

Focused ion beam micromachining of TiNi film on Si( 1 1 1 )

NASA Astrophysics Data System (ADS)

Xie, D. Z.; Ngoi, B. K. A.; Ong, A. S.; Fu, Y. Q.; Lim, B. H.

2003-11-01

Having an excellent shape memory effect, titanium-nickel (TiNi) thin films are often used for fabrication of microactuators in microelectromechanical systems. In this work, the Ga + focused ion beam (FIB) etching characteristics of TiNi thin films has been investigated. The thin films were deposited on Si(1 1 1) wafers by co-sputtering NiTi and Ti targets using a magnetron-sputtering system. Some patterns have been etched on the surface of the films by FIB. Atomic force microscopy has been used to analyze the surface morphology of the etched areas. It is found that the etched depth depends linearly on the ion dose per area with a slope of 0.259 μm/(nC/μm 2). However, the etching depth decreases with increasing the ion beam current. The root-mean-square (RMS) surface roughness changes nonlinearly with ion dose and reaches a minimum of about 5.00 nm at a dose of about 0.45 nC/μm 2. The RMS decreases with increasing ion beam current and reaches about 4.00 nm as the ion beam current is increased to 2 nA.

Suboxide/subnitride formation on Ta masks during magnetic material etching by reactive plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hu; Muraki, Yu; Karahashi, Kazuhiro

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 +}more » 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.« less

Repair of a Mirror Coating on a Large Optic for High Laser Damage Applications using Ion Milling and Over-Coating Methods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Ella Suzanne; Bellum, John Curtis; Kletecka, Damon E.

When an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface, and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched. Repairsmore » were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO 2 and SiO 2 layers for high reflection at 1054 nm at 45° incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO 2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm 2. Finally, the repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 – 61.0 J/cm 2.« less

Repair of a mirror coating on a large optic for high laser damage applications using ion milling and over-coating methods

NASA Astrophysics Data System (ADS)

Field, Ella S.; Bellum, John C.; Kletecka, Damon E.

2017-01-01

When an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched. Repairs were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO2 and SiO2 layers for high reflection at 1054 nm at 45 deg incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO2 to evaluate the ability of each repair method to restore the coating's high laser-induced damage threshold (LIDT) of 64.0 J/cm2. The repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 to 61.0 J/cm2.

Repair of a mirror coating on a large optic for high laser damage applications using ion milling and over-coating methods

DOE PAGES

Field, Ella S.; Bellum, John C.; Kletecka, Damon E.

2016-07-08

Here, when an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched.more » Repairs were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO 2 and SiO 2 layers for high reflection at 1054 nm at 45 deg incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm 2. The repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 to 61.0 J/cm 2.« less

Repair of a Mirror Coating on a Large Optic for High Laser Damage Applications using Ion Milling and Over-Coating Methods.

DOE PAGES

Field, Ella Suzanne; Bellum, John Curtis; Kletecka, Damon E.

2016-06-01

When an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface, and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched. Repairsmore » were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO 2 and SiO 2 layers for high reflection at 1054 nm at 45° incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO 2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm 2. Finally, the repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 – 61.0 J/cm 2.« less

Repair of a mirror coating on a large optic for high laser damage applications using ion milling and over-coating methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Ella S.; Bellum, John C.; Kletecka, Damon E.

Here, when an optical coating is damaged, deposited incorrectly, or is otherwise unsuitable, the conventional method to restore the optic often entails repolishing the optic surface, which can incur a large cost and long lead time. We propose three alternative options to repolishing, including (i) burying the unsuitable coating under another optical coating, (ii) using ion milling to etch the unsuitable coating completely from the optic surface and then recoating the optic, and (iii) using ion milling to etch through a number of unsuitable layers, leaving the rest of the coating intact, and then recoating the layers that were etched.more » Repairs were made on test optics with dielectric mirror coatings according to the above three options. The mirror coatings to be repaired were quarter wave stacks of HfO 2 and SiO 2 layers for high reflection at 1054 nm at 45 deg incidence in P-polarization. One of the coating layers was purposely deposited incorrectly as Hf metal instead of HfO2 to evaluate the ability of each repair method to restore the coating’s high laser-induced damage threshold (LIDT) of 64.0 J/cm 2. The repaired coating with the highest resistance to laser-induced damage was achieved using repair method (ii) with an LIDT of 49.0 to 61.0 J/cm 2.« less

High density plasma etching of magnetic devices

NASA Astrophysics Data System (ADS)

Jung, Kee Bum

Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3-rich to achieve the highest etch rates. Several different mask materials were investigated, including photoresist, thermal oxide and deposited oxide. Photoresist etches very rapidly in CO/NH 3 and use of a hard mask is necessary to achieve pattern transfer. Due to its physically dominated nature, the CO/NH3 chemistry appears suited to shallow etch depth (≤0.5mum) applications, but mask erosion leads to sloped feature sidewalls for deeper features.

Cooperative simulation of lithography and topography for three-dimensional high-aspect-ratio etching

NASA Astrophysics Data System (ADS)

Ichikawa, Takashi; Yagisawa, Takashi; Furukawa, Shinichi; Taguchi, Takafumi; Nojima, Shigeki; Murakami, Sadatoshi; Tamaoki, Naoki

2018-06-01

A topography simulation of high-aspect-ratio etching considering transports of ions and neutrals is performed, and the mechanism of reactive ion etching (RIE) residues in three-dimensional corner patterns is revealed. Limited ion flux and CF2 diffusion from the wide space of the corner is found to have an effect on the RIE residues. Cooperative simulation of lithography and topography is used to solve the RIE residue problem.

Enhanced etching of tin-doped indium oxide due to surface modification by hydrogen ion injection

NASA Astrophysics Data System (ADS)

Li, Hu; Karahashi, Kazuhiro; Friederich, Pascal; Fink, Karin; Fukasawa, Masanaga; Hirata, Akiko; Nagahata, Kazunori; Tatsumi, Tetsuya; Wenzel, Wolfgang; Hamaguchi, Satoshi

2018-06-01

It is known that the etching yield (i.e., sputtering yield) of tin-doped indium oxide (ITO) by hydrocarbon ions (CH x +) is higher than its corresponding physical sputtering yield [H. Li et al., J. Vac. Sci. Technol. A 33, 060606 (2015)]. In this study, the effects of hydrogen in the incident hydrocarbon ion beam on the etching yield of ITO have been examined experimentally and theoretically with the use of a mass-selected ion beam system and by first-principles quantum mechanical (QM) simulation. As in the case of ZnO [H. Li et al., J. Vac. Sci. Technol. A 35, 05C303 (2017)], mass-selected ion beam experiments have shown that the physical sputtering yield of ITO by chemically inert Ne ions increases after a pretreatment of the ITO film by energetic hydrogen ion injection. First-principles QM simulation of the interaction of In2O3 with hydrogen atoms shows that hydrogen atoms embedded in In2O3 readily form hydroxyl (OH) groups and weaken or break In–O bonds around the hydrogen atoms, making the In2O3 film less resistant to physical sputtering. This is consistent with experimental observation of the enhanced etching yields of ITO by CH x + ions, considering the fact that hydrogen atoms of the incident CH x + ions are embedded into ITO during the etching process.

Elemental depth profiles and plasma etching rates of positive-tone electron beam resists after sequential infiltration synthesis of alumina

NASA Astrophysics Data System (ADS)

Ozaki, Yuki; Ito, Shunya; Hiroshiba, Nobuya; Nakamura, Takahiro; Nakagawa, Masaru

2018-06-01

By scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (STEM–EDS), we investigated the elemental depth profiles of organic electron beam resist films after the sequential infiltration synthesis (SIS) of inorganic alumina. Although a 40-nm-thick poly(methyl methacrylate) (PMMA) film was entirely hybridized with alumina, an uneven distribution was observed near the interface between the substrate and the resist as well as near the resist surface. The uneven distribution was observed around the center of a 100-nm-thick PMMA film. The thicknesses of the PMMA and CSAR62 resist films decreased almost linearly as functions of plasma etching period. The comparison of etching rate among oxygen reactive ion etching, C3F8 reactive ion beam etching (RIBE), and Ar ion beam milling suggested that the SIS treatment enhanced the etching resistance of the electron beam resists to chemical reactions rather than to ion collisions. We proposed oxygen- and Ar-assisted C3F8 RIBE for the fabrication of silica imprint molds by electron beam lithography.

Lead Pipe Scale Analysis Using Broad-Beam Argon Ion Milling to Elucidate Drinking Water Corrosion

EPA Science Inventory

Herein, we compared the characterization of lead pipe scale removed from a drinking water distribution system using two different cross section methods (conventional polishing and argon ion beam etching). The pipe scale solids were analyzed using scanning electron microscopy (SEM...

Fabrication of ultra-high aspect ratio (>160:1) silicon nanostructures by using Au metal assisted chemical etching

NASA Astrophysics Data System (ADS)

Li, Hailiang; Ye, Tianchun; Shi, Lina; Xie, Changqing

2017-12-01

We present a facile and effective approach for fabricating high aspect ratio, dense and vertical silicon nanopillar arrays, using a combination of metal etching following electron-beam lithography and Au metal assisted chemical etching (MacEtch). Ti/Au nanostructures used as catalysts in MacEtch are formed by single layer resist-based electron-beam exposure followed by ion beam etching. The effects of MacEtch process parameters, including half period, etching time, the concentrations of H2O2 and HF, etching temperature and drying method are systematically investigated. Especially, we demonstrate an enhancement of etching quality by employing cold MacEtch process, and an enhancement in preventing the collapse of high aspect ratio nanostructures by employing low surface tension rinse liquid and natural evaporation in the drying stage. Using an optimized MacEtch process, vertical silicon nanopillar arrays with a period of 250 nm and aspect ratio up to 160:1 are realized. Our results should be instructive for exploring the achievable aspect ratio limit in silicon nanostructures and may find potential applications in photovoltaic devices, thermoelectric devices and x-ray diffractive optics.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Weiye; Sridhar, Shyam; Liu, Lei

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) andmore » 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.« less

Smoothing single-crystalline SiC surfaces by reactive ion etching using pure NF{sub 3} and NF{sub 3}/Ar mixture gas plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tasaka, Akimasa, E-mail: aki-tasaka-load@yahoo.co.jp; Kotaka, Yuki; Oda, Atsushi

2014-09-01

In pure NF{sub 3} plasma, the etching rates of four kinds of single-crystalline SiC wafer etched at NF{sub 3} pressure of 2 Pa were the highest and it decreased with an increase in NF{sub 3} pressure. On the other hand, they increased with an increase in radio frequency (RF) power and were the highest at RF power of 200 W. A smooth surface was obtained on the single-crystalline 4H-SiC after reactive ion etching at NF{sub 3}/Ar gas pressure of 2 Pa and addition of Ar to NF{sub 3} plasma increased the smoothness of SiC surface. Scanning electron microscopy observation revealed that the numbermore » of pillars decreased with an increase in the Ar-concentration in the NF{sub 3}/Ar mixture gas. The roughness factor (R{sub a}) values were decreased from 51.5 nm to 25.5 nm for the As-cut SiC, from 0.25 nm to 0.20 nm for the Epi-SiC, from 5.0 nm to 0.7 nm for the Si-face mirror-polished SiC, and from 0.20 nm to 0.16 nm for the C-face mirror-polished SiC by adding 60% Ar to the NF{sub 3} gas. Both the R{sub a} values of the Epi- and the C-face mirror-polished wafer surfaces etched using the NF{sub 3}/Ar (40:60) plasma were similar to that treated with mirror polishing, so-called the Catalyst-Referred Etching (CARE) method, with which the lowest roughness of surface was obtained among the chemical mirror polishing methods. Etching duration for smoothing the single-crystalline SiC surface using its treatment was one third of that with the CARE method.« less

Tissue response to peritoneal implants

NASA Technical Reports Server (NTRS)

Picha, G. J.

1980-01-01

Peritoneal implants were fabricated from poly 2-OH, ethyl methacrylate (HEMA), polyetherurethane (polytetramethylene glycol 1000 MW, 1,4 methylene disocynate, and ethyl diamine), and untreated and sputter treated polytetrafluoroethylene (PTFE). The sputter treated PTFE implants were produced by an 8 cm diameter argon ion source. The treated samples consisted of ion beam sputter polished samples, sputter etched samples (to produce a microscopic surface cone texture) and surface pitted samples (produced by ion beam sputtering to result in 50 microns wide by 100 microns deep square pits). These materials were implanted in rats for periods ranging from 30 minutes to 14 days. The results were evaluated with regard to cell type and attachment kinetics onto the different materials. Scanning electron microscopy and histological sections were also evaluated. In general the smooth hydrophobic surfaces attracted less cells than the ion etched PTFE or the HEMA samples. The ion etching was observed to enhance cell attachment, multinucleated giant cell (MNGC) formation, cell to cell contact, and fibrous capsule formation. The cell responsed in the case of ion etched PTFE to an altered surface morphology. However, equally interesting was the similar attachment kinetics of HEMA verses the ion etched PTFE. However, HEMA resulted in a markedly different response with no MNGC's formation, minimal to no capsule formation, and sample coverage by a uniform cell layer.

Ion beam sputter etching of orthopedic implanted alloy MP35N and resulting effects on fatigue

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Christopher, M.; Bahnuik, E.; Wang, S.

1981-01-01

The effects of two types of argon ion sputter etched surface structures on the tensile stress fatigue properties of orthopedic implant alloy MP35N were investigated. One surface structure was a natural texture resulting from direct bombardment by 1 keV argon ions. The other structure was a pattern of square holes milled into the surface by a 1 keV argon ion beam through a Ni screen mask. The etched surfaces were subjected to tensile stress only in fatigue tests designed to simulate the cyclic load conditions experienced by the stems of artificial hip joint implants. Both types of sputter etched surface structures were found to reduce the fatigue strength below that of smooth surface MP35N.

Homogeneous alignment of nematic liquid crystals by ion beam etched surfaces

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Mahmood, R.; Johnson, D. L.

1979-01-01

A wide range of ion beam etch parameters capable of producing uniform homogeneous alignment of nematic liquid crystals on SiO2 films are discussed. The alignment surfaces were generated by obliquely incident (angles of 5 to 25 deg) argon ions with energies in the range of 0.5 to 2.0 KeV, ion current densities of 0.1 to 0.6 mA sq cm and etch times of 1 to 9 min. A smaller range of ion beam parameters (2.0 KeV, 0.2 mA sq cm, 5 to 10 deg and 1 to 5 min.) were also investigated with ZrO2 films and found suitable for homogeneous alignment. Extinction ratios were very high (1000), twist angles were small ( or = 3 deg) and tilt-bias angles very small ( or = 1 deg). Preliminary scanning electron microscopy results indicate a parallel oriented surface structure on the ion beam etched surfaces which may determine alignment.

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.

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.

A molecular dynamics analysis of ion irradiation of ultrathin amorphous carbon films

NASA Astrophysics Data System (ADS)

Qi, J.; Komvopoulos, K.

2016-09-01

Molecular dynamics (MD) simulations provide insight into nanoscale problems where continuum description breaks down, such as the modeling of ultrathin films. Amorphous carbon (a-C) films are commonly used as protective overcoats in various contemporary technologies, including microelectromechanical systems, bio-implantable devices, optical lenses, and hard-disk drives. In all of these technologies, the protective a-C film must be continuous and very thin. For example, to achieve high storage densities (e.g., on the order of 1 Tb/in.2) in magnetic recording, the thickness of the a-C film used to protect the magnetic media and the recording head against mechanical wear and corrosion must be 2-3 nm. Inert ion irradiation is an effective post-deposition method for reducing the film thickness, while preserving the mechanical and chemical characteristics. In this study, MD simulations of Ar+ ion irradiated a-C films were performed to elucidate the effects of the ion incidence angle and ion kinetic energy on the film thickness and structure. The MD results reveal that the film etching rate exhibits a strong dependence on the ion kinetic energy and ion incidence angle, with a maximum etching rate corresponding to an ion incidence angle of ˜20°. It is also shown that Ar+ ion irradiation mainly affects the structure of the upper half of the ultrathin a-C film and that carbon atom hybridization is a strong function of the ion kinetic energy and ion incidence angle. The results of this study elucidate the effects of important ion irradiation parameters on the structure and thickness of ultrathin films and provide fundamental insight into the physics of dry etching.

Resonant tunneling device with two-dimensional quantum well emitter and base layers

DOEpatents

Simmons, J.A.; Sherwin, M.E.; Drummond, T.J.; Weckwerth, M.V.

1998-10-20

A double electron layer tunneling device is presented. Electrons tunnel from a two dimensional emitter layer to a two dimensional tunneling layer and continue traveling to a collector at a lower voltage. The emitter layer is interrupted by an isolation etch, a depletion gate, or an ion implant to prevent electrons from traveling from the source along the emitter to the drain. The collector is similarly interrupted by a backgate, an isolation etch, or an ion implant. When the device is used as a transistor, a control gate is added to control the allowed energy states of the emitter layer. The tunnel gate may be recessed to change the operating range of the device and allow for integrated complementary devices. Methods of forming the device are also set forth, utilizing epoxy-bond and stop etch (EBASE), pre-growth implantation of the backgate or post-growth implantation. 43 figs.

Resonant tunneling device with two-dimensional quantum well emitter and base layers

DOEpatents

Simmons, Jerry A.; Sherwin, Marc E.; Drummond, Timothy J.; Weckwerth, Mark V.

1998-01-01

A double electron layer tunneling device is presented. Electrons tunnel from a two dimensional emitter layer to a two dimensional tunneling layer and continue traveling to a collector at a lower voltage. The emitter layer is interrupted by an isolation etch, a depletion gate, or an ion implant to prevent electrons from traveling from the source along the emitter to the drain. The collector is similarly interrupted by a backgate, an isolation etch, or an ion implant. When the device is used as a transistor, a control gate is added to control the allowed energy states of the emitter layer. The tunnel gate may be recessed to change the operating range of the device and allow for integrated complementary devices. Methods of forming the device are also set forth, utilizing epoxy-bond and stop etch (EBASE), pre-growth implantation of the backgate or post-growth implantation.

Progress Report for the Joint Services Electronics Program

DTIC Science & Technology

1991-06-30

AIGaAs MODFET layers. Both wet etching and reactive ion etching have been used to fabricate the channels. The CAIBE method will also be investigated in...potential for fabricating nanometer scale device structures through surface modification of various types. Using this JSEP research as a foundation...Kerkhoven, "Calculation of velocity overshoot in submicron devices using an augmented drift-diffusion model," Solid-State Electron. (to appear). (JSEP/NSF

METHOD OF IMPROVING CORROSION RESISTANCE OF ZIRCONIUM

DOEpatents

Shannon, D.W.

1961-03-28

An improved intermediate rinse for zirconium counteracts an anomalous deposit that often results in crevices and outof-the-way places when ordinary water is used to rinse away a strong fluoride etching solution designed to promote passivation of the metal. The intermediate rinse, which is used after the etching solution and before the water, is characterized by a complexing agent for fluoride ions such as aluminum or zirconium nitrates or chlorides.

Controllable Fabrication of Non-Close-Packed Colloidal Nanoparticle Arrays by Ion Beam Etching

NASA Astrophysics Data System (ADS)

Yang, Jie; Zhang, Mingling; Lan, Xu; Weng, Xiaokang; Shu, Qijiang; Wang, Rongfei; Qiu, Feng; Wang, Chong; Yang, Yu

2018-06-01

Polystyrene (PS) nanoparticle films with non-close-packed arrays were prepared by using ion beam etching technology. The effects of etching time, beam current, and voltage on the size reduction of PS particles were well investigated. A slow etching rate, about 9.2 nm/min, is obtained for the nanospheres with the diameter of 100 nm. The rate does not maintain constant with increasing the etching time. This may result from the thermal energy accumulated gradually in a long-time bombardment of ion beam. The etching rate increases nonlinearly with the increase of beam current, while it increases firstly then reach its saturation with the increase of beam voltage. The diameter of PS nanoparticles can be controlled in the range from 34 to 88 nm. Based on the non-close-packed arrays of PS nanoparticles, the ordered silicon (Si) nanopillars with their average diameter of 54 nm are fabricated by employing metal-assisted chemical etching technique. Our results pave an effective way to fabricate the ordered nanostructures with the size less than 100 nm.

Self-terminated etching of GaN with a high selectivity over AlGaN under inductively coupled Cl2/N2/O2 plasma with a low-energy ion bombardment

NASA Astrophysics Data System (ADS)

Zhong, Yaozong; Zhou, Yu; Gao, Hongwei; Dai, Shujun; He, Junlei; Feng, Meixin; Sun, Qian; Zhang, Jijun; Zhao, Yanfei; DingSun, An; Yang, Hui

2017-10-01

Etching of GaN/AlGaN heterostructure by O-containing inductively coupled Cl2/N2 plasma with a low-energy ion bombardment can be self-terminated at the surface of the AlGaN layer. The estimated etching rates of GaN and AlGaN were 42 and 0.6 nm/min, respectively, giving a selective etching ratio of 70:1. To study the mechanism of the etching self-termination, detailed characterization and analyses were carried out, including X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It was found that in the presence of oxygen, the top surface of the AlGaN layer was converted into a thin film of (Al,Ga)Ox with a high bonding energy, which effectively prevented the underlying atoms from a further etching, resulting in a nearly self-terminated etching. This technique enables a uniform and reproducible fabrication process for enhancement-mode high electron mobility transistors with a p-GaN gate.

A junction-level optoelectronic characterization of etching-induced damage for third-generation HgCdTe infrared focal-plane array photodetectors

NASA Astrophysics Data System (ADS)

Wang, Peng; Wang, Yueming; Wu, Mingzai; Ye, Zhenhua

2018-06-01

Third-generation HgCdTe-based infrared focal plane arrays require high aspect ratio trenches with admissible etch induced damage at the surface and sidewalls for effectively isolating the pixels. In this paper, the high-density inductively coupled plasma enhanced reaction ion etching technique has been used for micro-mesa delineation of HgCdTe for third-generation infrared focal-plane array detectors. A nondestructive junction-level optoelectronic characterization method called laser beam induced current (LBIC) is used to evaluate the lateral junction extent of HgCdTe etch-induced damage scanning electron microscopy. It is found that the LBIC profiles exhibit evident double peaks and valleys phenomena. The lateral extent of etch induced mesa damage of ∼2.4 μm is obtained by comparing the LBIC profile and the scanning electron microscopy image of etched sample. This finding will guide us to nondestructively identify the distributions of the etching damages in large scale HgCdTe micro-mesa.

Etude fondamentale des mecanismes de gravure par plasma de materiaux de pointe: Application a la fabrication de dispositifs photoniques

NASA Astrophysics Data System (ADS)

Stafford, Luc

Advances in electronics and photonics critically depend upon plasma-based materials processing either for transferring small lithographic patterns into underlying materials (plasma etching) or for the growth of high-quality films. This thesis deals with the etching mechanisms of materials using high-density plasmas. The general objective of this work is to provide an original framework for the plasma-material interaction involved in the etching of advanced materials by putting the emphasis on complex oxides such as SrTiO3, (Ba,Sr)TiO 3 and SrBi2Ta2O9 films. Based on a synthesis of the descriptions proposed by different authors to explain the etching characteristics of simple materials in noble and halogenated plasma mixtures, we propose comprehensive rate models for physical and chemical plasma etching processes. These models have been successfully validated using experimental data published in literature for Si, Pt, W, SiO2 and ZnO. As an example, we have been able to adequately describe the simultaneous dependence of the etch rate on ion and reactive neutral fluxes and on the ion energy. From an exhaustive experimental investigation of the plasma and etching properties, we have also demonstrated that the validity of the proposed models can be extended to complex oxides such as SrTiO3, (Ba,Sr)TiO 3 and SrBi2Ta2O9 films. We also reported for the first time physical aspects involved in plasma etching such as the influence of the film microstructural properties on the sputter-etch rate and the influence of the positive ion composition on the ion-assisted desorption dynamics. Finally, we have used our deep investigation of the etching mechanisms of STO films and the resulting excellent control of the etch rate to fabricate a ridge waveguide for photonic device applications. Keywords: plasma etching, sputtering, adsorption and desorption dynamics, high-density plasmas, plasma diagnostics, advanced materials, photonic applications.

Attachment and spreadout study of 3T3 cells onto PP track etched films

NASA Astrophysics Data System (ADS)

Smolko, Eduardo; Mazzei, Ruben; Tadey, Daniel; Lombardo, Daniel

2001-12-01

Polymer surface modifications are obtained by the application of radiation treatments and other physico-chemical methods: fission fragment (ff) irradiation and etching. The biocompatibility of the surface is then observed by cell seeding and cell adhesion experiments. Approaches to improvement of the cell adhesion are obtained by different methods: for example, in PS, cell adhesion is improved after ion implantation; in PMMA, after bombarding the polymer, the surface is reconditioned with surfactants and proteins and in PVDF, cell adhesion is assayed on nuclear tracks membranes. In this work, we obtained important cell adhesion improvements in PP films by irradiation with swift heavy ions and subsequent etching of the nuclear tracks. We use BOPP (isotactic -25 μm thickness). Irrradiations were performed with a Cf-252 californium ff source. The source has a heavy ff and a light one, with 160-200 MeV energy divided among them corresponding to ff energies between 1 and 2 MeV/amu. A chemical etching procedure consisting of a solution of sulphuric acid and chromium three oxide at 85 °C was used. The 3T3 NIH fibroblast cell line was used for the cell adhesion experiment. Here we report for the first time, the results of a series of experiments by varying the ff fluence and the etching time showing that attachment and spreadout of cells are very much improved in this cell line according to the number of pores and the pore size.

Ion beam enhanced etching of LiNbO 3

NASA Astrophysics Data System (ADS)

Schrempel, F.; Gischkat, Th.; Hartung, H.; Kley, E.-B.; Wesch, W.

2006-09-01

Single crystals of z- and x-cut LiNbO 3 were irradiated at room temperature and 15 K using He +- and Ar +-ions with energies of 40 and 350 keV and ion fluences between 5 × 10 12 and 5 × 10 16 cm -2. The damage formation investigated with Rutherford backscattering spectrometry (RBS) channeling analysis depends on the irradiation temperature as well as the ion species. For instance, He +-irradiation of z-cut material at 300 K provokes complete amorphization at 2.0 dpa (displacements per target atom). In contrast, 0.4 dpa is sufficient to amorphize the LiNbO 3 in the case of Ar +-irradiation. Irradiation at 15 K reduces the number of displacements per atom necessary for amorphization. To study the etching behavior, 400 nm thick amorphous layers were generated via multiple irradiation with He +- and Ar +-ions of different energies and fluences. Etching was performed in a 3.6% hydrofluoric (HF) solution at 40 °C. Although the etching rate of the perfect crystal is negligible, that of the amorphized regions amounts to 80 nm min -1. The influence of the ion species, the fluence, the irradiation temperature and subsequent thermal treatment on damage and etching of LiNbO 3 are discussed.

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.

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.

Molecular dynamics analysis of silicon chloride ion incidence during Si etching in Cl-based plasmas: Effects of ion incident energy, angle, and neutral radical-to-ion flux ratio

NASA Astrophysics Data System (ADS)

Nakazaki, Nobuya; Eriguchi, Koji; Ono, Kouichi

2014-10-01

Profile anomalies and surface roughness are critical issues to be resolved in plasma etching of nanometer-scale microelectronic devices, which in turn requires a better understanding of the effects of ion incident energy and angle on surface reaction kinetics. This paper presents a classical molecular dynamics (MD) simulation of Si(100) etching by energetic Clx+ (x = 1-2) and SiClx+ (x = 0-4) ion beams with different incident energies Ei = 20-500 eV and angles θi = 0-85°, with and without low-energy neutral Cl radicals (neutral-to-ion flux ratios Γn/Γi = 0 and 100). An improved Stillinger-Weber interatomic potential was used for the Si/Cl system. Numerical results indicated that in Cl+, Cl2+, SiCl3+, and SiCl4+ incidences for θi = 0° and Γn/Γi = 0, the etching occurs in the whole Ei range investigated; on the other hand, in SiCl+ and SiCl2+ incidences, the deposition occurs at low Ei < 300 and 150 eV, respectively, while the etching occurs at further increased Ei. For SiCl+ and SiCl2+, the transition energies from deposition and etching become lowered for Γn/Γi = 100. Numerical results further indicated that in the SiCl+ incidence for Γn/Γi = 0, the etching occurs in the whole θi range investigated for Ei >= 300 eV; on the other hand, for Ei = 100 and 150 eV, the deposition occurs at low θi < 60° and 40°, respectively, while the etching occurs at further increased θi; in addition, for Ei <= 50 eV, the deposition occurs in the whole θi range investigated.

Microfabrication of high performance optical diaphragm by plasma ion beam etching technology

NASA Astrophysics Data System (ADS)

Mestreau, Agnes; Bernardet, Henri; Dancoing, Guy; Godechot, Xavier; Pezant, Christian; Stenger, Vincent; Cousin, Bernard; Etcheto, Pierre; Otrio, Georges

2018-04-01

This paper, "Microfabrication of high performance optical diaphragm by plasma ion beam etching technology," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

Beam Simulation Studies of Plasma-Surface Interactions in Fluorocarbon Etching of Silicon and Silicon Dioxide

NASA Astrophysics Data System (ADS)

Gray, David C.

1992-01-01

A molecular beam apparatus has been constructed which allows the synthesis of dominant species fluxes to a wafer surface during fluorocarbon plasma etching. These species include atomic F as the primary etchant, CF _2 as a potential polymer forming precursor, and Ar^{+} or CF _{rm x}^{+} type ions. Ionic and neutral fluxes employed are within an order of magnitude of those typical of fluorocarbon plasmas and are well characterized through the use of in -situ probes. Etching yields and product distributions have been measured through the use of in-situ laser interferometry and line-of-sight mass spectrometry. XPS studies of etched surfaces were performed to assess surface chemical bonding states and average surface stoichiometry. A useful design guide was developed which allows optimal design of straight -tube molecular beam dosers in the collisionally-opaque regime. Ion-enhanced surface reaction kinetics have been studied as a function of the independently variable fluxes of free radicals and ions, as well as ion energy and substrate temperature. We have investigated the role of Ar ^{+} ions in enhancing the chemistries of F and CF_2 separately, and in combination on undoped silicon and silicon dioxide surfaces. We have employed both reactive and inert ions in the energy range most relevant to plasma etching processes, 20-500 eV, through the use of Kaufman and ECR type ion sources. The effect of increasing ion energy on the etching of fluorine saturated silicon and silicon dioxide surfaces was quantified through extensions of available low energy physical sputtering theory. Simple "site"-occupation models were developed for the quantification of the ion-enhanced fluorine etching kinetics in these systems. These models are suitable for use in topography evolution simulators (e.g. SAMPLE) for the predictive modeling of profile evolution in non-depositing fluorine-based plasmas such as NF_3 and SF_6. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.) (Abstract shortened with permission of school.).

High aspect ratio sub-15 nm silicon trenches from block copolymer templates.

PubMed

Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Chourou, S T; Hong, Sung Woo; Olynick, Deirdre L; Russell, Thomas P

2012-11-08

High-aspect-ratio sub-15-nm silicon trenches are fabricated directly from plasma etching of a block copolymer mask. A novel method that combines a block copolymer reconstruction process and reactive ion etching is used to make the polymer mask. Silicon trenches are characterized by various methods and used as a master for subsequent imprinting of different materials. Silicon nanoholes are generated from a block copolymer with cylindrical microdomains oriented normal to the surface. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Progress in performance enhancement methods for capacitive silicon resonators

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Ono, Takahito

2017-11-01

In this paper, we review the progress in recent studies on the performance enhancement methods for capacitive silicon resonators. We provide information on various fabrication technologies and design considerations that can be employed to improve the performance of capacitive silicon resonators, including low motional resistance, small insertion loss, and high quality factor (Q). This paper contains an overview of device structures and working principles, fabrication technologies consisting of hermetic packaging, deep reactive-ion etching and neutral beam etching, and design considerations including mechanically coupled, movable electrode structures and piezoresistive heat engines.

Ion Beam Etching: Replication of Micro Nano-structured 3D Stencil Masks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, Patrick; Guibert, Edouard; Mikhailov, Serguei

2009-03-10

Ion beam LIGA allows the etching of 3D nano-structures by direct writing with a nano-sized beam. However, this is a relatively time consuming process. We propose here another approach for etching structures on large surfaces and faster, compared to the direct writing process. This approach consists of replicating 3D structured masks, by scanning an unfocused ion beam. A polymer substrate is placed behind the mask, as in UV photolithography. But the main advantage is that the 3D structure of the mask can be replicated into the polymer. For that purpose, the masks (developped at LMIS1, EPFL) are made of amore » silicon nitride membrane 100 nm thick, on which 3D gold structures up to 200 nm thick, are deposited. The 3D Au structures are made with the nanostencil method, based on successive gold deposition. The IMA institute, from HE-Arc, owns a High Voltage Engineering 1.7 MV Tandetron with both solid and gaseous negative ion sources, able to generate ions from almost every chemical element in a broad range of energies comprised between 400 keV and 6.8 MeV. The beam composition and energy are chosen in such a way, that ions lose a significant fraction of their energy when passing through the thickest regions of the mask. Ions passing through thinner regions of the mask loose a smaller fraction of their energy and etch the polymer with larger thicknesses, allowing a replication of the mask into the polymer. For our trials, we have used a carbon beam with an energy of 500 keV. The beam was focussed to a diameter of 5 mm with solid slits, in order to avoid border effects and thus ensure a homogeneous dose distribution on the beam diameter. The feasibility of this technique has been demonstrated, allowing industrial applications for micro-mould fabrication, micro-fluidics and micro-optics.« less

Angular dependence of etch rates in the etching of poly-Si and fluorocarbon polymer using SF6, C4F8, and O2 plasmas

NASA Astrophysics Data System (ADS)

Min, Jae-Ho; Lee, Gyeo-Re; Lee, Jin-Kwan; Moon, Sang Heup; Kim, Chang-Koo

2004-05-01

The dependences of etch rates on the angle of ions incident on the substrate surface in four plasma/substrate systems that constitute the advanced Bosch process were investigated using a Faraday cage designed for the accurate control of the ion-incident angle. The four systems, established by combining discharge gases and substrates, were a SF6/poly-Si, a SF6/fluorocarbon polymer, an O2/fluorocarbon polymer, and a C4F8/Si. In the case of SF6/poly-Si, the normalized etch rates (NERs), defined as the etch rates normalized by the rate on the horizontal surface, were higher at all angles than values predicted from the cosine of the ion-incident angle. This characteristic curve shape was independent of changes in process variables including the source power and bias voltage. Contrary to the earlier case, the NERs for the O2/polymer decreased and eventually reached much lower values than the cosine values at angles between 30° and 70° when the source power was increased and the bias voltage was decreased. On the other hand, the NERs for the SF6/polymer showed a weak dependence on the process variables. In the case of C4F8/Si, which is used in the Bosch process for depositing a fluorocarbon layer on the substrate surface, the deposition rate varied with the ion incident angle, showing an S-shaped curve. These characteristic deposition rate curves, which were highly dependent on the process conditions, could be divided into four distinct regions: a Si sputtering region, an ion-suppressed polymer deposition region, an ion-enhanced polymer deposition region, and an ion-free polymer deposition region. Based on the earlier characteristic angular dependences of the etch (or deposition) rates in the individual systems, ideal process conditions for obtaining an anisotropic etch profile in the advanced Bosch process are proposed. .

New Methods of Sample Preparation for Atom Probe Specimens

NASA Technical Reports Server (NTRS)

Kuhlman, Kimberly, R.; Kowalczyk, Robert S.; Ward, Jennifer R.; Wishard, James L.; Martens, Richard L.; Kelly, Thomas F.

2003-01-01

Magnetite is a common conductive mineral found on Earth and Mars. Disk-shaped precipitates approximately 40 nm in diameter have been shown to have manganese and aluminum concentrations. Atom-probe field-ion microscopy (APFIM) is the only technique that can potentially quantify the composition of these precipitates. APFIM will be used to characterize geological and planetary materials, analyze samples of interest for geomicrobiology; and, for the metrology of nanoscale instrumentation. Prior to APFIM sample preparation was conducted by electropolishing, the method of sharp shards (MSS), or Bosch process (deep reactive ion etching) with focused ion beam (FIB) milling as a final step. However, new methods are required for difficult samples. Many materials are not easily fabricated using electropolishing, MSS, or the Bosch process, FIB milling is slow and expensive, and wet chemistry and the reactive ion etching are typically limited to Si and other semiconductors. APFIM sample preparation using the dicing saw is commonly used to section semiconductor wafers into individual devices following manufacture. The dicing saw is a time-effective method for preparing high aspect ratio posts of poorly conducting materials. Femtosecond laser micromachining is also suitable for preparation of posts. FIB time required is reduced by about a factor of 10 and multi-tip specimens can easily be fabricated using the dicing saw.

Effect of [gamma]-irradiation on latent tracks of polyethylene terephthalate (PET) film

NASA Astrophysics Data System (ADS)

Hiroki, A.; Asano, M.; Yamaki, T.; Yoshida, M.

2005-04-01

The pre-treatment effect of γ-irradiation on latent tracks of polyethylene terephthalate (PET) films bombarded with swift heavy ions was investigated by electric conductometry and scanning electron microscope (SEM) observation. The Xe-ion bombarded PET films were etched for 6 h in 0.2 M NaOH aqueous solution at 70 °C to prepare track-etched membranes. As γ-irradiation doses increased in the range of 0-160 kGy, the surface pore diameter obtained by SEM observation decreased while that obtained by conductometry became large. This inconsistent result between the two methods was due to an increase in the crosslinked region in the latent tracks caused by γ-irradiation.

High-aspect ratio micro- and nanostructures enabled by photo-electrochemical etching for sensing and energy harvesting applications

NASA Astrophysics Data System (ADS)

Alhalaili, Badriyah; Dryden, Daniel M.; Vidu, Ruxandra; Ghandiparsi, Soroush; Cansizoglu, Hilal; Gao, Yang; Saif Islam, M.

2018-03-01

Photo-electrochemical (PEC) etching can produce high-aspect ratio features, such as pillars and holes, with high anisotropy and selectivity, while avoiding the surface and sidewall damage caused by traditional deep reactive ion etching (DRIE) or inductively coupled plasma (ICP) RIE. Plasma-based techniques lead to the formation of dangling bonds, surface traps, carrier leakage paths, and recombination centers. In pursuit of effective PEC etching, we demonstrate an optical system using long wavelength (λ = 975 nm) infra-red (IR) illumination from a high-power laser (1-10 W) to control the PEC etching process in n-type silicon. The silicon wafer surface was patterned with notches through a lithography process and KOH etching. Then, PEC etching was introduced by illuminating the backside of the silicon wafer to enhance depth, resulting in high-aspect ratio structures. The effect of the PEC etching process was optimized by varying light intensities and electrolyte concentrations. This work was focused on determining and optimizing this PEC etching technique on silicon, with the goal of expanding the method to a variety of materials including GaN and SiC that are used in designing optoelectronic and electronic devices, sensors and energy harvesting devices.

Adhesive bonding of ion beam textured metals and fluoropolymers

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1978-01-01

An electron bombardment argon ion source was used to ion etch various metals and fluoropolymers. The metal and fluoropolymers were exposed to (0.5 to 1.0) keV Ar ions at ion current densities of (0.2 to 1.5) mA/sq cm for various exposure times. The resulting surface texture is in the form of needles or spires whose vertical dimensions may range from tenths to hundreds of micrometers, depending on the selection of beam energy, ion current density, and etch time. The bonding of textured surfaces is accomplished by ion beam texturing mating pieces of either metals or fluoropolymers and applying a bonding agent which wets in and around the microscopic cone-like structures. After bonding, both tensile and shear strength measurements were made on the samples. Also tested, for comparison's sake, were untextured and chemically etched fluoropolymers. The results of these measurements are presented.

Adhesive bonding of ion beam textured metals and fluoropolymers

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1978-01-01

An electron-bombardment argon ion source was used to ion-etch various metals and fluoropolymers. The metal and fluoropolymers were exposed to (0.5 to 1.0)-keV Ar ions at ion current densities of 0.2 to 1.5 mA/sq cm for various exposure times. The resulting surface texture is in the form of needles or spires whose vertical dimensions may range from tenths to hundreds of micrometers, depending on the selection of beam energy, ion current density, and etch time. The bonding of textured surfaces is accomplished by ion-beam texturing mating pieces of either metals or fluoropolymers and applying a bonding agent which wets in and around the microscopic conelike structures. After bonding, both tensile and shear strength measurements were made on the samples. Also tested, for comparison's sake, were untextured and chemically etched fluoropolymers. The results of these measurements are presented in this paper.

Chloride (Cl-) ion-mediated shape control of palladium nanoparticles

NASA Astrophysics Data System (ADS)

Nalajala, Naresh; Chakraborty, Arup; Bera, Bapi; Neergat, Manoj

2016-02-01

The shape control of Pd nanoparticles is investigated using chloride (Cl-) ions as capping agents in an aqueous medium in the temperature range of 60-100 °C. With weakly adsorbing and strongly etching Cl- ions, oxygen plays a crucial role in shape control. The experimental factors considered are the concentration of the capping agents, reaction time and reaction atmosphere. Thus, Pd nanoparticles of various shapes with high selectivity can be synthesized. Moreover, the removal of Cl- ions from the nanoparticle surface is easier than that of Br- ions (moderately adsorbing and etching) and I- ions (strongly adsorbing and weakly etching). The cleaned Cl- ion-mediated shape-controlled Pd nanoparticles are electrochemically characterized and the order of the half-wave potential of the oxygen reduction reaction in oxygen-saturated 0.1 M HClO4 solution is of the same order as that observed with single-crystal Pd surfaces.

Damage-Free Smooth-Sidewall InGaAs Nanopillar Array by Metal-Assisted Chemical Etching.

PubMed

Kong, Lingyu; Song, Yi; Kim, Jeong Dong; Yu, Lan; Wasserman, Daniel; Chim, Wai Kin; Chiam, Sing Yang; Li, Xiuling

2017-10-24

Producing densely packed high aspect ratio In 0.53 Ga 0.47 As nanostructures without surface damage is critical for beyond Si-CMOS nanoelectronic and optoelectronic devices. However, conventional dry etching methods are known to produce irreversible damage to III-V compound semiconductors because of the inherent high-energy ion-driven process. In this work, we demonstrate the realization of ordered, uniform, array-based In 0.53 Ga 0.47 As pillars with diameters as small as 200 nm using the damage-free metal-assisted chemical etching (MacEtch) technology combined with the post-MacEtch digital etching smoothing. The etching mechanism of In x Ga 1-x As is explored through the characterization of pillar morphology and porosity as a function of etching condition and indium composition. The etching behavior of In 0.53 Ga 0.47 As, in contrast to higher bandgap semiconductors (e.g., Si or GaAs), can be interpreted by a Schottky barrier height model that dictates the etching mechanism constantly in the mass transport limited regime because of the low barrier height. A broader impact of this work relates to the complete elimination of surface roughness or porosity related defects, which can be prevalent byproducts of MacEtch, by post-MacEtch digital etching. Side-by-side comparison of the midgap interface state density and flat-band capacitance hysteresis of both the unprocessed planar and MacEtched pillar In 0.53 Ga 0.47 As metal-oxide-semiconductor capacitors further confirms that the surface of the resultant pillars is as smooth and defect-free as before etching. MacEtch combined with digital etching offers a simple, room-temperature, and low-cost method for the formation of high-quality In 0.53 Ga 0.47 As nanostructures that will potentially enable large-volume production of In 0.53 Ga 0.47 As-based devices including three-dimensional transistors and high-efficiency infrared photodetectors.

Three-dimensional patterning in polymer optical waveguides using focused ion beam milling

NASA Astrophysics Data System (ADS)

Kruse, Kevin; Burrell, Derek; Middlebrook, Christopher

2016-07-01

Waveguide (WG) photonic-bridge taper modules are designed for symmetric planar coupling between silicon WGs and single-mode fibers (SMFs) to minimize photonic chip and packaging footprint requirements with improving broadband functionality. Micromachined fabrication and evaluation of polymer WG tapers utilizing high-resolution focused ion beam (FIB) milling is performed and presented. Polymer etch rates utilizing the FIB and optimal methods for milling polymer tapers are identified for three-dimensional patterning. Polymer WG tapers with low sidewall roughness are manufactured utilizing FIB milling and optically tested for fabrication loss. FIB platforms utilize a focused beam of ions (Ga+) to etch submicron patterns into substrates. Fabricating low-loss polymer WG taper prototypes with the FIB before moving on to mass-production techniques provides theoretical understanding of the polymer taper and its feasibility for connectorization devices between silicon WGs and SMFs.

TrackEtching - A Java based code for etched track profile calculations in SSNTDs

NASA Astrophysics Data System (ADS)

Muraleedhara Varier, K.; Sankar, V.; Gangadathan, M. P.

2017-09-01

A java code incorporating a user friendly GUI has been developed to calculate the parameters of chemically etched track profiles of ion-irradiated solid state nuclear track detectors. Huygen's construction of wavefronts based on secondary wavelets has been used to numerically calculate the etched track profile as a function of the etching time. Provision for normal incidence and oblique incidence on the detector surface has been incorporated. Results in typical cases are presented and compared with experimental data. Different expressions for the variation of track etch rate as a function of the ion energy have been utilized. The best set of values of the parameters in the expressions can be obtained by comparing with available experimental data. Critical angle for track development can also be calculated using the present code.

Fabrication of precision high quality facets on molecular beam epitaxy material

DOEpatents

Petersen, Holly E.; Goward, William D.; Dijaili, Sol P.

2001-01-01

Fabricating mirrored vertical surfaces on semiconductor layered material grown by molecular beam epitaxy (MBE). Low energy chemically assisted ion beam etching (CAIBE) is employed to prepare mirrored vertical surfaces on MBE-grown III-V materials under unusually low concentrations of oxygen in evacuated etching atmospheres of chlorine and xenon ion beams. UV-stabilized smooth-surfaced photoresist materials contribute to highly vertical, high quality mirrored surfaces during the etching.

Damage to the Silicon Substrate by Reactive Ion Etching Detected by a Slow Positron Beam

NASA Astrophysics Data System (ADS)

Wei, Long; Tabuki, Yasushi; Tanigawa, Shoichiro

1993-01-01

Defects in reactive ion-etched Si have been investigated by means of a slow positron beam. A thin carbon-containing film (<30 Å) was formed on the Si surface after reactive ion etching (RIE). Vacancy-type defects, which were estimated to distribute over 1200 Å in depth by numerical fitting using the positron trapping model, were observed in the damaged subsurface region of Si. Aside from ion bombardment, ultraviolet radiation is also presumed to affect the formation of vacancies, interstitials in oxide and the formation of vacancies in Si substrate. The ionization-enhanced diffusion (IED) mechanism is expected to promote the diffusion of vacancies and interstitials into Si substrate.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, D.J.; Warner, J.A.; LeBarron, N.

Processes that use energetic ions for large substrates require that the time-averaged erosion effects from the ion flux be uniform across the surface. A numerical model has been developed to determine this flux and its effects on surface etching of a silica/photoresist combination. The geometry of the source and substrate is very similar to a typical deposition geometry with single or planetary substrate rotation. The model was used to tune an inert ion-etching process that used single or multiple Kaufman sources to less than 3% uniformity over a 30-cm aperture after etching 8 {micro}m of material. The same model canmore » be used to predict uniformity for ion-assisted deposition (IAD).« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yin Yunpeng; Sawin, Herbert H.

The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followedmore » the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.« less

Ion track etching revisited: I. Correlations between track parameters in aged polymers

NASA Astrophysics Data System (ADS)

Fink, D.; Muñoz H., G.; García A., H.; Vacik, J.; Hnatowicz, V.; Kiv, A.; Alfonta, L.

2018-04-01

Some yet poorly understood problems of etching of pristine and swift heavy ion track-irradiated aged polymers were treated, by applying conductometry across the irradiated foils during etching. The onset times of etchant penetration across pristine foils, and the onset times of the different etched track regimes in irradiated foils were determined for polymers of various proveniences, fluences and ages, as well as their corresponding etching speeds. From the results, correlations of the parameters with each other were deduced. The normalization of these parameters enables one to compare irradiated polymer foils of different origin and treatment with one another. In a number of cases, also polymeric gel formation and swelling occur which influence the track etching behaviour. The polymer degradation during aging influences the track etching parameters, which differ from each other on both sides of the foils. With increasing sample age, these differences increase.

Reactive ion etching effects on carbon-doped Ge2Sb2Te5 phase change material in CF4/Ar plasma

NASA Astrophysics Data System (ADS)

Shen, Lanlan; Song, Sannian; Song, Zhitang; Li, Le; Guo, Tianqi; Liu, Bo; Wu, Liangcai; Cheng, Yan; Feng, Songlin

2016-10-01

Recently, carbon-doped Ge2Sb2Te5 (CGST) has been proved to be a high promising material for future phase change memory technology. In this article, reactive ion etching (RIE) of phase change material CGST films is studied using CF4/Ar gas mixture. The effects on gas-mixing ratio, RF power, gas pressure on the etch rate, etch profile and roughness of the CGST film are investigated. Conventional phase change material Ge2Sb2Te5 (GST) films are simultaneously studied for comparison. Compared with GST film, 10 % more CF4 is needed for high etch rate and 10% less CF4 for good anisotropy of CGST due to more fluorocarbon polymer deposition during CF4 etching. The trends of etch rates and roughness of CGST with varying RF power and chamber pressure are similar with those of GST. Furthermore, the etch rate of CGST are more easily to be saturated when higher RF power is applied.

Manufacturing Methods for the Production of Field Effect Electron Emitters from Oxide-Metal Composites.

DTIC Science & Technology

1977-12-01

Internal Zone Melting, Oxide-Metal Eutectic Structures ABSTRACT (Continue X reverae elde II neceaetrry end Identity by block nwbor* -^>This report...To- Uranium (0/U) Ratio B. Storage of "As-Received" Powders C. Moisture Content D. Oxidation Properties E. Sintering Properties F. Particle Size... Nickel - Vanadium 3.3 Nickel -Al203 3.4 Nickel -Tungsten 3.5 Copper-410 Stainless Steel C. Etching 1. Chemical Etching 2. Thermal Annealing 3. Ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kokkoris, George; Boudouvis, Andreas G.; Gogolides, Evangelos

An integrated framework for the neutral flux calculation inside trenches and holes during plasma etching is described, and a comparison between the two types of structure in a number of applications is presented. First, a detailed and functional set of equations for the neutral and ion flux calculations inside long trenches and holes with cylindrical symmetry is explicitly formulated. This set is based on early works [T. S. Cale and G. B. Raupp, J. Vac. Sci. Technol. B 8, 1242 (1990); V. K. Singh et al., J. Vac. Sci. Technol. B 10, 1091 (1992)], and includes new equations for themore » case of holes with cylindrical symmetry. Second, a method for the solution of the respective numerical task, i.e., one or a set of linear or nonlinear integral equations, is described. This method includes a coupling algorithm with a surface chemistry model and resolves the singularity problem of the integral equations. Third, the fluxes inside trenches and holes are compared. The flux from reemission is the major portion of the local flux at the bottom of both types of structure. The framework is applied in SiO{sub 2} etching by fluorocarbon plasmas to predict the increased intensity of reactive ion etching lag in SiO{sub 2} holes compared to trenches. It is also applied in deep Si etching: By calculating the flux of F atoms at the bottom of very high aspect ratio (up to 150) Si trenches and holes during the gas chopping process, the aspect ratio at which the flux of F atoms is eliminated and etching practically stops is estimated.« less

Xe- and U-tracks in apatite and muscovite near the etching threshold

NASA Astrophysics Data System (ADS)

Wauschkuhn, Bastian; Jonckheere, Raymond; Ratschbacher, Lothar

2015-01-01

Ion irradiation of a wedge-shaped Durango apatite backed by a mica detector allows investigating ion track ranges and etching properties at different points along the tracks. Transmission profiles obtained by irradiation with 2 × 106 cm-2 11.1 MeV/amu 132Xe and 2 × 106 cm-2 11.1 MeV/amu 238U parallel to the apatite c-axis correspond to ranges calculated with SRIM (Xe: 76.3 μm; U: 81.1 μm). However, the measured profiles show much greater etchable track-length variations than the calculated longitudinal straggles. The probable cause is that the length deficit exhibits significant variation from track to track. The measured length deficit in muscovite is in agreement with most existing data. In contrast, the length deficit in apatite appears to be close to zero, which is in conflict with all earlier estimates. This probably results from the etching properties of the apatite basal face, which permit surface-assisted sub-threshold etching of track sections in the nuclear stopping regime. These sections are not accessible from the opposite direction, i.e. by etching towards the endpoint of the tracks or in the direction of the ion beam. This conclusion is supported by the fact that linear dislocations are revealed in apatite basal faces and by the observation of imperfect etch pits that are separated from the etched ion track channel by a section that appears unetched under the microscope.

Microstructural characterization of Ti-6Al-4V alloy subjected to the duplex SMAT/plasma nitriding.

PubMed

Pi, Y; Faure, J; Agoda-Tandjawa, G; Andreazza, C; Potiron, S; Levesque, A; Demangel, C; Retraint, D; Benhayoune, H

2013-09-01

In this study, microstructural characterization of Ti-6Al-4V alloy, subjected to the duplex surface mechanical attrition treatment (SMAT)/nitriding treatment, leading to improve its mechanical properties, was carried out through novel and original samples preparation methods. Instead of acid etching which is limited for morphological characterization by scanning electron microscopy (SEM), an original ion polishing method was developed. Moreover, for structural characterization by transmission electron microscopy (TEM), an ion milling method based with the use of two ions guns was also carried out for cross-section preparation. To demonstrate the efficiency of the two developed methods, morphological investigations were done by traditional SEM and field emission gun SEM. This was followed by structural investigations through selected area electron diffraction (SAED) coupled with TEM and X-ray diffraction techniques. The results demonstrated that ionic polishing allowed to reveal a variation of the microstructure according to the surface treatment that could not be observed by acid etching preparation. TEM associated to SAED and X-ray diffraction provided information regarding the nanostructure compositional changes induced by the duplex SMAT/nitriding process. Copyright © 2013 Wiley Periodicals, Inc.

Atomistic simulations of graphite etching at realistic time scales.

PubMed

Aussems, D U B; Bal, K M; Morgan, T W; van de Sanden, M C M; Neyts, E C

2017-10-01

Hydrogen-graphite interactions are relevant to a wide variety of applications, ranging from astrophysics to fusion devices and nano-electronics. In order to shed light on these interactions, atomistic simulation using Molecular Dynamics (MD) has been shown to be an invaluable tool. It suffers, however, from severe time-scale limitations. In this work we apply the recently developed Collective Variable-Driven Hyperdynamics (CVHD) method to hydrogen etching of graphite for varying inter-impact times up to a realistic value of 1 ms, which corresponds to a flux of ∼10 20 m -2 s -1 . The results show that the erosion yield, hydrogen surface coverage and species distribution are significantly affected by the time between impacts. This can be explained by the higher probability of C-C bond breaking due to the prolonged exposure to thermal stress and the subsequent transition from ion- to thermal-induced etching. This latter regime of thermal-induced etching - chemical erosion - is here accessed for the first time using atomistic simulations. In conclusion, this study demonstrates that accounting for long time-scales significantly affects ion bombardment simulations and should not be neglected in a wide range of conditions, in contrast to what is typically assumed.

Toward Edge-Defined Holey Boron Nitride Nanosheets

NASA Technical Reports Server (NTRS)

Lin, Yi; Liao, Yunlong; Chen, Zhongfan; Connell, John W.

2015-01-01

"Holey" two-dimensional (2D) nanosheets with well-defined holy morphology and edge chemistry are highly desirable for applications such as energy storage, catalysis, sensing, transistors, and molecular transport/separation. For example, holey grapheme is currently under extensive investigation for energy storage applications because of the improvement in ion transport due to through the thickness pathways provided by the holes. Without the holes, the 2D materials have significant limitations for such applications in which efficient ion transport is important. As part of an effort to apply this approach to other 2D nanomaterials, a method to etch geometrically defined pits or holes on the basal plane surface of hexagonal boron nitride (h-BN) nanosheets has been developed. The etching, conducted via heating in ambient air using metal nanoparticles as catalysts, was facile, controllable, and scalable. Starting h-BN layered crystals were etched and subsequently exfoliated into boron nitride nanosheets (BNNSs). The as-etched and exfoliated h-BN nanosheets possessed defined pit and hole shapes that were comprised of regulated nanostructures at the edges. The current finding are the first step toward the bulk preparation of holey BNNSs with defined holes and edges.

High electronegativity multi-dipolar electron cyclotron resonance plasma source for etching by negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stamate, E.; Draghici, M.

2012-04-15

A large area plasma source based on 12 multi-dipolar ECR plasma cells arranged in a 3 x 4 matrix configuration was built and optimized for silicon etching by negative ions. The density ratio of negative ions to electrons has exceeded 300 in Ar/SF{sub 6} gas mixture when a magnetic filter was used to reduce the electron temperature to about 1.2 eV. Mass spectrometry and electrostatic probe were used for plasma diagnostics. The new source is free of density jumps and instabilities and shows a very good stability for plasma potential, and the dominant negative ion species is F{sup -}. Themore » magnetic field in plasma volume is negligible and there is no contamination by filaments. The etching rate by negative ions measured in Ar/SF{sub 6}/O{sub 2} mixtures was almost similar with that by positive ions reaching 700 nm/min.« less

Review Article: Unraveling synergistic effects in plasma-surface processes by means of beam experiments

PubMed Central

von Keudell, Achim; Corbella, Carles

2017-01-01

The interaction of plasmas with surfaces is dominated by synergistic effects between incident ions and radicals. Film growth is accelerated by the ions, providing adsorption sites for incoming radicals. Chemical etching is accelerated by incident ions when chemical etching products are removed from the surface by ion sputtering. The latter is the essence of anisotropic etching in microelectronics, as elucidated by the seminal paper of Coburn and Winters [J. Appl. Phys. 50, 3189 (1979)]. However, ion-radical-synergisms play also an important role in a multitude of other systems, which are described in this article: (1) hydrocarbon thin film growth from methyl radicals and hydrogen atoms; (2) hydrocarbon thin film etching by ions and reactive neutrals; (3) plasma inactivation of bacteria; (4) plasma treatment of polymers; and (5) oxidation mechanisms during reactive magnetron sputtering of metal targets. All these mechanisms are unraveled by using a particle beam experiment to mimic the plasma–surface interface with the advantage of being able to control the species fluxes independently. It clearly shows that the mechanisms in action that had been described by Coburn and Winters [J. Appl. Phys. 50, 3189 (1979)] are ubiquitous. PMID:29104360

Effect of nonsinusoidal bias waveforms on ion energy distributions and fluorocarbon plasma etch selectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agarwal, Ankur; Kushner, Mark J.; Iowa State University, Department of Electrical and Computer Engineering, 104 Marston Hall, Ames, Iowa 50011-2151

2005-09-15

The distributions of ion energies incident on the wafer significantly influence feature profiles and selectivity during plasma etching. Control of ion energies is typically obtained by varying the amplitude or frequency of a radio frequency sinusoidal bias voltage applied to the substrate. The resulting ion energy distribution (IED), though, is generally broad. Controlling the width and shape of the IED can potentially improve etch selectivity by distinguishing between threshold energies of surface processes. In this article, control of the IED was computationally investigated by applying a tailored, nonsinusoidal bias waveform to the substrate of an inductively coupled plasma. The waveformmore » we investigated, a quasi-dc negative bias having a short positive pulse each cycle, produced a narrow IED whose width was controllable based on the length of the positive spike and frequency. We found that the selectivity between etching Si and SiO{sub 2} in fluorocarbon plasmas could be controlled by adjusting the width and energy of the IED. Control of the energy of a narrow IED enables etching recipes that transition between speed and selectivity without change of gas mixture.« less

Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa

2013-10-14

Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachmentmore » properties.« less

WSi2/Si multilayer sectioning by reactive ion etching for multilayer Laue lens fabrication

NASA Astrophysics Data System (ADS)

Bouet, N.; Conley, R.; Biancarosa, J.; Divan, R.; Macrander, A. T.

2010-09-01

Reactive ion etching (RIE) has been employed in a wide range of fields such as semiconductor fabrication, MEMS (microelectromechanical systems), and refractive x-ray optics with a large investment put towards the development of deep RIE. Due to the intrinsic differing chemistries related to reactivity, ion bombardment, and passivation of materials, the development of recipes for new materials or material systems can require intense effort and resources. For silicon in particular, methods have been developed to provide reliable anisotropic profiles with good dimensional control and high aspect ratios1,2,3, high etch rates, and excellent material to mask etch selectivity. A multilayer Laue lens4 is an x-ray focusing optic, which is produced by depositing many layers of two materials with differing electron density in a particular stacking sequence where the each layer in the stack satisfies the Fresnel zone plate law. When this stack is sectioned to allow side-illumination with radiation, the diffracted exiting radiation will constructively interfere at the focal point. Since the first MLLs were developed at Argonne in the USA in 20064, there have been published reports of MLL development efforts in Japan5, and, very recently, also in Germany6. The traditional technique for sectioning multilayer Laue lens (MLL) involves mechanical sectioning and polishing7, which is labor intensive and can induce delamination or structure damage and thereby reduce yield. If a non-mechanical technique can be used to section MLL, it may be possible to greatly shorten the fabrication cycle, create more usable optics from the same amount of deposition substrate, and perhaps develop more advanced structures to provide greater stability or flexibility. Plasma etching of high aspect-ratio multilayer structures will also expand the scope for other types of optics fabrication (such as gratings, zone plates, and so-on). However, well-performing reactive ion etching recipes have been developed for only a small number of materials, and even less recipes exist for concurrent etching of more than one element so a fully material specific process needs to be developed. In this paper, sectioning of WSi2/Si multilayers for MLL fabrication using fluorinated gases is investigated. The main goals were to demonstrate the feasibility of this technique, achievement of high anisotropy, adequate sidewall roughness control and high etching rates. We note that this development for MLL sidewalls should be distinguished from work on improving aspect ratios in traditional Fresnel zone plates. Aspect ratios for MLL sidewalls are not similarly constrained.

Reactive ion etching of GaN using BCl 3, BCl 3/Ar and BCl 3/ N 2 gas plasmas

NASA Astrophysics Data System (ADS)

Basak, D.; Nakanishi, T.; Sakai, S.

2000-04-01

Reactive ion etching (RIE) of GaN has been performed using BCl 3 and additives, Ar and N 2, to BCl 3 plasma. The etch rate, surface roughness and the etch profile have been investigated. The etch rate of GaN is found to be 104 nm/min at rf power of 200 W, pressure of 2 Pa, with 9.5 sccm flow rate of BCl 3. The addition of 5 sccm of Ar to 9.5 sccm of BCl 3 reduces the etch rate of GaN while the addition of N 2 does not influence the etch rate significantly. The RIE of GaN layer with BCl 3/Ar and BCl 3/N 2 results in a smoother surface compared to surfaces etched with BCl 3 only. The etched side-wall in BCl 3 plasma makes an angle of 60° with the normal surface, and the angle of inclination is more in cases of BCl 3/Ar and BCl 3/N 2 plasmas. The RIE induced damage to the surface is measured qualitatively by PL measurements. It is observed that the damage to the etched surfaces is similar for all the plasmas.

Fast semi-analytical method for precise prediction of ion energy distribution functions and sheath electric field in multi-frequency capacitively coupled plasmas

NASA Astrophysics Data System (ADS)

Chen, Wencong; Zhang, Xi; Diao, Dongfeng

2018-05-01

We propose a fast semi-analytical method to predict ion energy distribution functions and sheath electric field in multi-frequency capacitively coupled plasmas, which are difficult to measure in commercial plasma reactors. In the intermediate frequency regime, the ion density within the sheath is strongly modulated by the low-frequency sheath electric field, making the time-independent ion density assumption employed in conventional models invalid. Our results are in a good agreement with experimental measurements and computer simulations. The application of this method will facilitate the understanding of ion–material interaction mechanisms and development of new-generation plasma etching devices.

Fracture Tests of Etched Components Using a Focused Ion Beam Machine

NASA Technical Reports Server (NTRS)

Kuhn, Jonathan, L.; Fettig, Rainer K.; Moseley, S. Harvey; Kutyrev, Alexander S.; Orloff, Jon; Powers, Edward I. (Technical Monitor)

2000-01-01

Many optical MEMS device designs involve large arrays of thin (0.5 to 1 micron components subjected to high stresses due to cyclic loading. These devices are fabricated from a variety of materials, and the properties strongly depend on size and processing. Our objective is to develop standard and convenient test methods that can be used to measure the properties of large numbers of witness samples, for every device we build. In this work we explore a variety of fracture test configurations for 0.5 micron thick silicon nitride membranes machined using the Reactive Ion Etching (RIE) process. Testing was completed using an FEI 620 dual focused ion beam milling machine. Static loads were applied using a probe. and dynamic loads were applied through a piezo-electric stack mounted at the base of the probe. Results from the tests are presented and compared, and application for predicting fracture probability of large arrays of devices are considered.

Monte Carlo simulations of secondary electron emission due to ion beam milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahady, Kyle; Tan, Shida; Greenzweig, Yuval

We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes thismore » study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.« less

Infrared Photodiodes Made by Low Energy Ion Etching of Molecular Beam Epitaxy Grown Mercury-Cadmium Alloy

NASA Astrophysics Data System (ADS)

Yoo, Sung-Shik

Ion etching was used to form junctions on the p-type (111)B Hg_{1-x}Cd_ {x}Te grown by Molecular Beam Epitaxy(MBE). When Hg_{1-x}Cd_{x}Te layers are etched by Ar ions at energies ranging between 300 and 450eV, the top Hg_{1 -x}Cd_{x}Te layer is converted to n-type. The converted region is electrically characterized as a defective n^+-region near the surface, and a low doped n^--region exist below the damaged region. The total thickness of the converted n-type layer was found to be considerable. These results suggest that the creation of the n-type layer is due to the filling of mercury vacancies by mercury atoms displaced by the Ar ion irradiation on the surface. For the performance of the resulting photodiodes on MBE grown (111)B Hg_{1-x}Cd _{x}Te using this technique, the dynamic resistances at 80K are one order of magnitude less than those of junctions made on Liquid Phase Epitaxially and Bulk grown Hg_{1 -x}Cd_{x}Te. The ion etching technique was compared with ion implantation technique by fabricating diodes on the same MBE grown (111)B Hg _{1-x}Cd_{x}Te layers. The result of the comparison illustrates that ion etching technique is as good as ion implantation technique for the fabrication of Hg_{1-x}Cd _{x}Te photodiodes. Also it is believed that the performance of the diodes is limited by a relatively large density of twin defects usually found in MBE grown (111)B Hg_{1-x}Cd _{x}Te.

Nanofabrication on unconventional substrates using transferred hard masks

DOE PAGES

Li, Luozhou; Bayn, Igal; Lu, Ming; ...

2015-01-15

Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantationmore » are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.« less

Fabrication of submicron structures in nanoparticle/polymer composite by holographic lithography and reactive ion etching

NASA Astrophysics Data System (ADS)

Zhang, A. Ping; He, Sailing; Kim, Kyoung Tae; Yoon, Yong-Kyu; Burzynski, Ryszard; Samoc, Marek; Prasad, Paras N.

2008-11-01

We report on the fabrication of nanoparticle/polymer submicron structures by combining holographic lithography and reactive ion etching. Silica nanoparticles are uniformly dispersed in a (SU8) polymer matrix at a high concentration, and in situ polymerization (cross-linking) is used to form a nanoparticle/polymer composite. Another photosensitive SU8 layer cast upon the nanoparticle/SU8 composite layer is structured through holographic lithography, whose pattern is finally transferred to the nanoparticle/SU8 layer by the reactive ion etching process. Honeycomb structures in a submicron scale are experimentally realized in the nanoparticle/SU8 composite.

Etching Characteristics of VO2 Thin Films Using Inductively Coupled Cl2/Ar Plasma

NASA Astrophysics Data System (ADS)

Ham, Yong-Hyun; Efremov, Alexander; Min, Nam-Ki; Lee, Hyun Woo; Yun, Sun Jin; Kwon, Kwang-Ho

2009-08-01

A study on both etching characteristics and mechanism of VO2 thin films in the Cl2/Ar inductively coupled plasma was carried. The variable parameters were gas pressure (4-10 mTorr) and input power (400-700 W) at fixed bias power of 150 W and initial mixture composition of 25% Cl2 + 75% Ar. It was found that an increase in both gas pressure and input power results in increasing VO2 etch rate while the etch selectivity over photoresist keeps a near to constant values. Plasma diagnostics by Langmuir probes and zero-dimensional plasma model provided the data on plasma parameters, steady-state densities and fluxes of active species on the etched surface. The model-based analysis of the etch mechanism showed that, for the given ranges of operating conditions, the VO2 etch kinetics corresponds to the transitional regime of ion-assisted chemical reaction and is influenced by both neutral and ion fluxes with a higher sensitivity to the neutral flux.

Barium-strontium-titanate etching characteristics in chlorinated discharges

NASA Astrophysics Data System (ADS)

Stafford, Luc; Margot, Joëlle; Langlois, Olivier; Chaker, Mohamed

2003-07-01

The etching characteristics of barium-strontium-titanate (BST) were investigated using a high-density plasma sustained by surface waves at 190 MHz in Ar/Cl2 gas mixtures. The etch rate was examined as a function of both the total gas pressure and the Cl2 fraction in Ar/Cl2 using a wafer temperature of 10 °C. The results were correlated to positive ion density and plasma composition obtained from Langmuir probes and mass spectrometry. The BST etch rate was found to increase linearly with the positive ion density and to decrease with increasing chlorine atom concentration. This result indicates that for the temperature conditions used, the interaction between chlorine and BST yields compounds having a volatility that is lower than the original material. As a consequence, the contribution of neutral atomic Cl atoms to the etch mechanism is detrimental, thereby reducing the etch rate. As the wafer temperature increases, the role of chemistry in the etching process is enhanced.

Ultra-Shallow Depth Profiling of Arsenic Implants in Silicon by Hydride Generation-Inductively Coupled Plasma Atomic Emission Spectrometry

NASA Astrophysics Data System (ADS)

Matsubara, Atsuko; Kojima, Hisao; Itoga, Toshihiko; Kanehori, Keiichi

1995-08-01

High resolution depth profiling of arsenic (As) implanted into silicon wafers by a chemical technique is described. Silicon wafers are precisely etched through repeated oxidation by hydrogen peroxide solution and dissolution of the oxide by hydrofluoric acid solution. The etched silicon thickness is determined by inductively-coupled plasma atomic emission spectrometry (ICP-AES). Arsenic concentration is determined by hydride generation ICP-AES (HG-ICP-AES) with prereduction using potassium iodide. The detection limit of As in a 4-inch silicon wafer is 2.4×1018 atoms/cm3. The etched silicon thickness is controlled to less than 4±2 atomic layers. Depth profiling of an ultra-shallow As diffusion layer with the proposed method shows good agreement with profiling using the four-probe method or secondary ion mass spectrometry.

Die singulation method and package formed thereby

DOEpatents

Anderson, Robert C [Tucson, AZ; Shul, Randy J [Albuquerque, NM; Clews, Peggy J [Tijeras, NM; Baker, Michael S [Albuquerque, NM; De Boer, Maarten P [Albuquerque, NM

2012-08-07

A method is disclosed for singulating die from a substrate having a sacrificial layer and one or more device layers, with a retainer being formed in the device layer(s) and anchored to the substrate. Deep Reactive Ion Etching (DRIE) etching of a trench through the substrate from the bottom side defines a shape for each die. A handle wafer is then attached to the bottom side of the substrate, and the sacrificial layer is etched to singulate the die and to form a frame from the retainer and the substrate. The frame and handle wafer, which retain the singulated die in place, can be attached together with a clamp or a clip and to form a package for the singulated die. One or more stops can be formed from the device layer(s) to limit a sliding motion of the singulated die.

Microtrenching-free two-step reactive ion etching of 4H-SiC using NF{sub 3}/HBr/O{sub 2} and Cl{sub 2}/O{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tseng, Yuan-Hung, E-mail: yhtseng.ee99g@nctu.edu.tw; Tsui, Bing-Yue

2014-05-15

In this paper, the authors performed a reactive ion etch of a 4H-SiC substrate with a gas mixture of NF{sub 3}, HBr, and O{sub 2}, resulting in a microtrenching-free etch. The etch rate was 107.8 nm/min, and the selectivity over the oxide hard mask was ∼3.85. Cross-sectional scanning electron microscopy showed no microtrenching compared with etches using plasmas of NF{sub 3}, NF{sub 3}/HBr, and NF{sub 3}/O{sub 2}. Analyzing a variety of HBr/O{sub 2} mixing ratios, the authors discuss the additive effect of each gas and their respective potential mechanisms for alleviating microtrenching. To increase the radius of gyration of the bottommore » corners, they introduced a second etch step with Cl{sub 2}/O{sub 2} plasma. Fabricating simple metal-oxide-semiconductor capacitors on the two-step etched surface, the authors found that the electrical characteristics of the etched sample were nearly the same as the nonetched sample.« less

Consequences of atomic layer etching on wafer scale uniformity in inductively coupled plasmas

NASA Astrophysics Data System (ADS)

Huard, Chad M.; Lanham, Steven J.; Kushner, Mark J.

2018-04-01

Atomic layer etching (ALE) typically divides the etching process into two self-limited reactions. One reaction passivates a single layer of material while the second preferentially removes the passivated layer. As such, under ideal conditions the wafer scale uniformity of ALE should be independent of the uniformity of the reactant fluxes onto the wafers, provided all surface reactions are saturated. The passivation and etch steps should individually asymptotically saturate after a characteristic fluence of reactants has been delivered to each site. In this paper, results from a computational investigation are discussed regarding the uniformity of ALE of Si in Cl2 containing inductively coupled plasmas when the reactant fluxes are both non-uniform and non-ideal. In the parameter space investigated for inductively coupled plasmas, the local etch rate for continuous processing was proportional to the ion flux. When operated with saturated conditions (that is, both ALE steps are allowed to self-terminate), the ALE process is less sensitive to non-uniformities in the incoming ion flux than continuous etching. Operating ALE in a sub-saturation regime resulted in less uniform etching. It was also found that ALE processing with saturated steps requires a larger total ion fluence than continuous etching to achieve the same etch depth. This condition may result in increased resist erosion and/or damage to stopping layers using ALE. While these results demonstrate that ALE provides increased etch depth uniformity, they do not show an improved critical dimension uniformity in all cases. These possible limitations to ALE processing, as well as increased processing time, will be part of the process optimization that includes the benefits of atomic resolution and improved uniformity.

Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas

PubMed Central

2014-01-01

In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF4/O2, C4F8/O2 and SF6/O2) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF6/O2 due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF4/O2 and C4F8/O2. Low-volatile C-F compound etching byproducts from C4F8/O2 were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF6/O2, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology. PMID:25278821

Model of wet chemical etching of swift heavy ions tracks

NASA Astrophysics Data System (ADS)

Gorbunov, S. A.; Malakhov, A. I.; Rymzhanov, R. A.; Volkov, A. E.

2017-10-01

A model of wet chemical etching of tracks of swift heavy ions (SHI) decelerated in solids in the electronic stopping regime is presented. This model takes into account both possible etching modes: etching controlled by diffusion of etchant molecules to the etching front, and etching controlled by the rate of a reaction of an etchant with a material. Olivine ((Mg0.88Fe0.12)2SiO4) crystals were chosen as a system for modeling. Two mechanisms of chemical activation of olivine around the SHI trajectory are considered. The first mechanism is activation stimulated by structural transformations in a nanometric track core, while the second one results from neutralization of metallic atoms by generated electrons spreading over micrometric distances. Monte-Carlo simulations (TREKIS code) form the basis for the description of excitations of the electronic subsystem and the lattice of olivine in an SHI track at times up to 100 fs after the projectile passage. Molecular dynamics supplies the initial conditions for modeling of lattice relaxation for longer times. These simulations enable us to estimate the effects of the chemical activation of olivine governed by both mechanisms. The developed model was applied to describe chemical activation and the etching kinetics of tracks of Au 2.1 GeV ions in olivine. The estimated lengthwise etching rate (38 µm · h-1) is in reasonable agreement with that detected in the experiments (24 µm · h-1).

Iodine enhanced focused-ion-beam etching of silicon for photonic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schrauwen, Jonathan; Thourhout, Dries van; Baets, Roel

Focused-ion-beam etching of silicon enables fast and versatile fabrication of micro- and nanophotonic devices. However, large optical losses due to crystal damage and ion implantation make the devices impractical when the optical mode is confined near the etched region. These losses are shown to be reduced by the local implantation and etching of silicon waveguides with iodine gas enhancement, followed by baking at 300 deg. C. The excess optical loss in the silicon waveguides drops from 3500 to 1700 dB/cm when iodine gas is used, and is further reduced to 200 dB/cm after baking at 300 deg. C. We presentmore » elemental and chemical surface analyses supporting that this is caused by the desorption of iodine from the silicon surface. Finally we present a model to extract the absorption coefficient from the measurements.« less

Multi-functional micro electromechanical devices and method of bulk manufacturing same

NASA Technical Reports Server (NTRS)

Okojie, Robert S. (Inventor)

2004-01-01

A method of bulk manufacturing SiC sensors is disclosed and claimed. Materials other than SiC may be used as the substrate material. Sensors requiring that the SiC substrate be pierced are also disclosed and claimed. A process flow reversal is employed whereby the metallization is applied first before the recesses are etched into or through the wafer. Aluminum is deposited on the entire planar surface of the metallization. Photoresist is spun onto the substantially planar surface of the Aluminum which is subsequently masked (and developed and removed). Unwanted Aluminum is etched with aqueous TMAH and subsequently the metallization is dry etched. Photoresist is spun onto the still substantially planar surface of Aluminum and oxide and then masked (and developed and removed) leaving the unimidized photoresist behind. Next, ITO is applied over the still substantially planar surface of Aluminum, oxide and unimidized photoresist. Unimidized and exposed photoresist and ITO directly above it are removed with Acetone. Next, deep reactive ion etching attacks exposed oxide not protected by ITO. Finally, hot phosphoric acid removes the Al and ITO enabling wires to connect with the metallization. The back side of the SiC wafer may be also be etched.

Etching of Silicon in HBr Plasmas for High Aspect Ratio Features

NASA Technical Reports Server (NTRS)

Hwang, Helen H.; Meyyappan, M.; Mathad, G. S.; Ranade, R.

2002-01-01

Etching in semiconductor processing typically involves using halides because of the relatively fast rates. Bromine containing plasmas can generate high aspect ratio trenches, desirable for DRAM and MEMS applications, with relatively straight sidewalk We present scanning electron microscope images for silicon-etched trenches in a HBr plasma. Using a feature profile simulation, we show that the removal yield parameter, or number of neutrals removed per incident ion due to all processes (sputtering, spontaneous desorption, etc.), dictates the profile shape. We find that the profile becomes pinched off when the removal yield is a constant, with a maximum aspect ratio (AR) of about 5 to 1 (depth to height). When the removal yield decreases with increasing ion angle, the etch rate increases at the comers and the trench bottom broadens. The profiles have ARs of over 9:1 for yields that vary with ion angle. To match the experimentally observed etched time of 250 s for an AR of 9:1 with a trench width of 0.135 microns, we find that the neutral flux must be 3.336 x 10(exp 17)sq cm/s.

High definition surface micromachining of LiNbO 3 by ion implantation

NASA Astrophysics Data System (ADS)

Chiarini, M.; Bentini, G. G.; Bianconi, M.; De Nicola, P.

2010-10-01

High Energy Ion Implantation (HEII) of both medium and light mass ions has been successfully applied for the surface micromachining of single crystal LiNbO 3 (LN) substrates. It has been demonstrated that the ion implantation process generates high differential etch rates in the LN implanted areas, when suitable implantation parameters, such as ion species, fluence and energy, are chosen. In particular, when traditional LN etching solutions are applied to suitably ion implanted regions, etch rates values up to three orders of magnitude higher than the typical etching rates of the virgin material, are registered. Further, the enhancement in the etching rate has been observed on x, y and z-cut single crystalline material, and, due to the physical nature of the implantation process, it is expected that it can be equivalently applied also to substrates with different crystallographic orientations. This technique, associated with standard photolithographic technologies, allows to generate in a fast and accurate way very high aspect ratio relief micrometric structures on LN single crystal surface. In this work a description of the developed technology is reported together with some examples of produced micromachined structures: in particular very precisely defined self sustaining suspended structures, such as beams and membranes, generated on LN substrates, are presented. The developed technology opens the way to actual three dimensional micromachining of LN single crystals substrates and, due to the peculiar properties characterising this material, (pyroelectric, electro-optic, acousto-optic, etc.), it allows the design and the production of complex integrated elements, characterised by micrometric features and suitable for the generation of advanced Micro Electro Optical Systems (MEOS).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chen; Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu

Angstrom-level plasma etching precision is required for semiconductor manufacturing of sub-10 nm critical dimension features. Atomic layer etching (ALE), achieved by a series of self-limited cycles, can precisely control etching depths by limiting the amount of chemical reactant available at the surface. Recently, SiO{sub 2} ALE has been achieved by deposition of a thin (several Angstroms) reactive fluorocarbon (FC) layer on the material surface using controlled FC precursor flow and subsequent low energy Ar{sup +} ion bombardment in a cyclic fashion. Low energy ion bombardment is used to remove the FC layer along with a limited amount of SiO{sub 2} frommore » the surface. In the present article, the authors describe controlled etching of Si{sub 3}N{sub 4} and SiO{sub 2} layers of one to several Angstroms using this cyclic ALE approach. Si{sub 3}N{sub 4} etching and etching selectivity of SiO{sub 2} over Si{sub 3}N{sub 4} were studied and evaluated with regard to the dependence on maximum ion energy, etching step length (ESL), FC surface coverage, and precursor selection. Surface chemistries of Si{sub 3}N{sub 4} were investigated by x-ray photoelectron spectroscopy (XPS) after vacuum transfer at each stage of the ALE process. Since Si{sub 3}N{sub 4} has a lower physical sputtering energy threshold than SiO{sub 2}, Si{sub 3}N{sub 4} physical sputtering can take place after removal of chemical etchant at the end of each cycle for relatively high ion energies. Si{sub 3}N{sub 4} to SiO{sub 2} ALE etching selectivity was observed for these FC depleted conditions. By optimization of the ALE process parameters, e.g., low ion energies, short ESLs, and/or high FC film deposition per cycle, highly selective SiO{sub 2} to Si{sub 3}N{sub 4} etching can be achieved for FC accumulation conditions, where FC can be selectively accumulated on Si{sub 3}N{sub 4} surfaces. This highly selective etching is explained by a lower carbon consumption of Si{sub 3}N{sub 4} as compared to SiO{sub 2}. The comparison of C{sub 4}F{sub 8} and CHF{sub 3} only showed a difference in etching selectivity for FC depleted conditions. For FC accumulation conditions, precursor chemistry has a weak impact on etching selectivity. Surface chemistry analysis shows that surface fluorination and FC reduction take place during a single ALE cycle for FC depleted conditions. A fluorine rich carbon layer was observed on the Si{sub 3}N{sub 4} surface after ALE processes for which FC accumulation takes place. The angle resolved-XPS thickness calculations confirmed the results of the ellipsometry measurements in all cases.« less

Anisotropic etching of silicon in solutions containing tensioactive compounds

NASA Astrophysics Data System (ADS)

Zubel, Irena

2016-12-01

The results of investigations concerning anisotropic etching in 3M KOH and 25% TMAH solutions modified by tensioactive compounds such as alcohols, diols and a typical surfactant Triton X100 have been compared. Etching anisotropy was assessed on the basis of etch rates ratio V(110)/V(100). It was stated that the relation between surface tension of the solutions and etch rates of particular planes depend not only on the kind of surfactant but also on the kind of etching solution (KOH, TMAH). It points out an important role of TMA+ ions in the etching process, probably in the process of forming an adsorption layer, consisting of the molecules of tensioactive compounds on Si surface, which decides about etch rate. We have observed that this phenomenon occurs only at high concentration of TMA+ ions (25% TMAH). Reduction of TMAH concentration changes the properties of surfactant containing TMAH solutions. From all investigated solutions, the solutions that assured developing of (110) plane inclined at the angle of 45° to (100) substrate were selected. Such planes can be used as micromirrors in MOEMS structures. The solutions provide the etch rate ratio V(110)/V(100)<0.7, thus they were selected from hydroxide solutions containing surfactants. A simple way for etch rate anisotropy V(110)/V(100) assessment based on microscopic images etched structures has been proposed.

Fabrication of Buried Nanochannels From Nanowire Patterns

NASA Technical Reports Server (NTRS)

Choi, Daniel; Yang, Eui-Hyeok

2007-01-01

A method of fabricating channels having widths of tens of nanometers in silicon substrates and burying the channels under overlying layers of dielectric materials has been demonstrated. With further refinement, the method might be useful for fabricating nanochannels for manipulation and analysis of large biomolecules at single-molecule resolution. Unlike in prior methods, burying the channels does not involve bonding of flat wafers to the silicon substrates to cover exposed channels in the substrates. Instead, the formation and burying of the channels are accomplished in a more sophisticated process that is less vulnerable to defects in the substrates and less likely to result in clogging of, or leakage from, the channels. In this method, the first step is to establish the channel pattern by forming an array of sacrificial metal nanowires on an SiO2-on-Si substrate. In particular, the wire pattern is made by use of focused-ion-beam (FIB) lithography and a subsequent metallization/lift-off process. The pattern of metal nanowires is then transferred onto the SiO2 layer by reactive-ion etching, which yields sacrificial SiO2 nanowires covered by metal. After removal of the metal covering the SiO2 nanowires, what remains are SiO2 nanowires on an Si substrate. Plasma-enhanced chemical vapor deposition (PECVD) is used to form a layer of a dielectric material over the Si substrate and over the SiO2 wires on the surface of the substrate. FIB milling is then performed to form trenches at both ends of each SiO2 wire. The trenches serve as openings for the entry of chemicals that etch SiO2 much faster than they etch Si. Provided that the nanowires are not so long that the diffusion of the etching chemicals is blocked, the sacrificial SiO2 nanowires become etched out from between the dielectric material and the Si substrate, leaving buried channels. At the time of reporting the information for this article, channels 3 m long, 20 nm deep, and 80 nm wide (see figure) had been fabricated by this method.

Molecular dynamics simulations of plasma-surface interactions

NASA Astrophysics Data System (ADS)

Vegh, Joseph James

Molecular dynamics (MD) simulations are carried out to examine the fundamental mechanisms of plasma-surface interactions for various systems of interest to the semiconductor industry. These include ion and radical bombardment simulations of silicon, model low-k dielectric materials, and hydrocarbon (HC) based model photoresist materials. Simulations of fluorocarbon (FC), fluorine, and argon ion etching of silicon are conducted to find conditions under which the steady state etch of Si in the presence of a FC surface layer occurs. By varying the FC/F/Ar + ratios over a range of conditions, a correlation between FC layer thickness and Si etch yield (EY) is obtained that agrees qualitatively with experimentally observed trends. Further examination of this system allows for a Si etch mechanism to be proposed. This mechanism is similar to that seen in previous Si etching simulations where FC films do not form. The FC layer is observed to fluctuate in thickness during steady state Si etch, as the result of competition between FC deposition and sputtering of relatively large (> 6 C atoms) FC clusters during Ar+ impacts. This cluster ejection process is seen in all of the systems studied, and the properties of these clusters (composition, size, kinetic energy, etc.) are examined and catalogued. Ar+ and H radical and ion bombardment of a methylated Si surface is simulated as a model of plasma etching of low-k dielectric materials. The mechanisms and product distributions observed for 300 K H radical bombardment agree well with experiment. The etch characteristics of Ar+ bombardment are examined as a function of ion energy, and the corresponding variations in surface structure at high ion fluence are characterized. Various HC polymer surfaces are studied under ion and radical bombardment to examine plasma species interactions with model photoresist materials. Simulations of 100 eV Ar+ bombardment of polystyrene (PS), poly(4-methylstyrene) (P4MS), and poly(alpha-methylstyrene) (PalphaMS) show that for all of these materials (which have similar chemical compositions: PS: (C8H 8)x, PalphaMS and P4MS: (C9H 10)x), a densely crosslinked, dehydrogenated damaged layer forms at high ion fluences that greatly reduces the sputter yield of the material. During the initial transient period of bombardment, PalphaMS shows sputter yields nearly twice as high as P4MS or PS; polymer structure can play a role during the early stages of etch. Both the initial and high fluence etch characteristics match those observed experimentally. Further, fluctuations from cell-to-cell are much higher for the PalphaMS simulations, which may correlate to the increased roughening observed experimentally for PalphaMS. Additional simulations are carried out to examine the effects of H and F radical addition during Ar+ bombardment of PS. Both radical species are shown to inhibit and/or reverse the formation of the dehydrogenated layer that forms during bombardment with Ar+ alone. Further studies examine the effect of inert ion mass through simulations of Ar +, Xe+, and He+ bombardment of PS, amorphous C, and nanoscale features on diamond surfaces. The differences in penetration depth, kinetic energy deposition, and scattering patterns are suggestive of the differing etch characteristics that are seen experimentally for these ions. A discussion of dangling bond formation during ion bombardment and longer time-scale dynamics is also offered. A brief review of currently available potential energy functions is presented. Selected results from MD simulations that utilize some of these potentials and are closely related to the work in this dissertation are also discussed. The difficulties of expanding potential energy functions vis-a-vis commonly used ab initio quantum chemical calculations are also addressed.

Pyramidal pits created by single highly charged ions in BaF{sub 2} single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Said, A. S.; Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura; Heller, R.

2010-07-15

In various insulators, the impact of individual slow highly charged ions (eV-keV) creates surface nanostructures, whose size depends on the deposited potential energy. Here we report on the damage created on a cleaved BaF{sub 2} (111) surface by irradiation with 4.5xq keV highly charged xenon ions from a room-temperature electron-beam ion trap. Up to charge states q=36, no surface topographic changes on the BaF{sub 2} surface are observed by scanning force microscopy. The hidden stored damage, however, can be made visible using the technique of selective chemical etching. Each individual ion impact develops into a pyramidal etch pits, as canmore » be concluded from a comparison of the areal density of observed etch pits with the applied ion fluence (typically 10{sup 8} ions/cm{sup 2}). The dimensional analysis of the measured pits reveals the significance of the deposited potential energy in the creation of lattice distortions/defects in BaF{sub 2}.« less

The effect of reactive ion etch (RIE) process conditions on ReRAM device performance

NASA Astrophysics Data System (ADS)

Beckmann, K.; Holt, J.; Olin-Ammentorp, W.; Alamgir, Z.; Van Nostrand, J.; Cady, N. C.

2017-09-01

The recent surge of research on resistive random access memory (ReRAM) devices has resulted in a wealth of different materials and fabrication approaches. In this work, we describe the performance implications of utilizing a reactive ion etch (RIE) based process to fabricate HfO2 based ReRAM devices, versus a more unconventional shadow mask fabrication approach. The work is the result of an effort to increase device yield and reduce individual device size. Our results show that choice of RIE etch gas (SF6 versus CF4) is critical for defining the post-etch device profile (cross-section), and for tuning the removal of metal layers used as bottom electrodes in the ReRAM device stack. We have shown that etch conditions leading to a tapered profile for the device stack cause poor electrical performance, likely due to metal re-deposition during etching, and damage to the switching layer. These devices exhibit nonlinear I-V during the low resistive state, but this could be improved to linear behavior once a near-vertical etch profile was achieved. Device stacks with vertical etch profiles also showed an increase in forming voltage, reduced switching variability and increased endurance.

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.

Effects of hard mask etch on final topography of advanced phase shift masks

NASA Astrophysics Data System (ADS)

Hortenbach, Olga; Rolff, Haiko; Lajn, Alexander; Baessler, Martin

2017-07-01

Continuous shrinking of the semiconductor device dimensions demands steady improvements of the lithographic resolution on wafer level. These requirements challenge the photomask industry to further improve the mask quality in all relevant printing characteristics. In this paper topography of the Phase Shift Masks (PSM) was investigated. Effects of hard mask etch on phase shift uniformity and mask absorber profile were studied. Design of experiments method (DoE) was used for the process optimization, whereas gas composition, bias power of the hard mask main etch and bias power of the over-etch were varied. In addition, influence of the over-etch time was examined at the end of the experiment. Absorber depth uniformity, sidewall angle (SWA), reactive ion etch lag (RIE lag) and through pitch (TP) dependence were analyzed. Measurements were performed by means of Atomic-force microscopy (AFM) using critical dimension (CD) mode with a boot-shaped tip. Scanning electron microscope (SEM) cross-section images were prepared to verify the profile quality. Finally CD analysis was performed to confirm the optimal etch conditions. Significant dependence of the absorber SWA on hard mask (HM) etch conditions was observed revealing an improvement potential for the mask absorber profile. It was found that hard mask etch can leave a depth footprint in the absorber layer. Thus, the etch depth uniformity of hard mask etch is crucial for achieving a uniform phase shift over the active mask area. The optimized hard mask etch process results in significantly improved mask topography without deterioration of tight CD specifications.

Bio-inspired Fabrication of Complex Hierarchical Structure in Silicon.

PubMed

Gao, Yang; Peng, Zhengchun; Shi, Tielin; Tan, Xianhua; Zhang, Deqin; Huang, Qiang; Zou, Chuanping; Liao, Guanglan

2015-08-01

In this paper, we developed a top-down method to fabricate complex three dimensional silicon structure, which was inspired by the hierarchical micro/nanostructure of the Morpho butterfly scales. The fabrication procedure includes photolithography, metal masking, and both dry and wet etching techniques. First, microscale photoresist grating pattern was formed on the silicon (111) wafer. Trenches with controllable rippled structures on the sidewalls were etched by inductively coupled plasma reactive ion etching Bosch process. Then, Cr film was angled deposited on the bottom of the ripples by electron beam evaporation, followed by anisotropic wet etching of the silicon. The simple fabrication method results in large scale hierarchical structure on a silicon wafer. The fabricated Si structure has multiple layers with uniform thickness of hundreds nanometers. We conducted both light reflection and heat transfer experiments on this structure. They exhibited excellent antireflection performance for polarized ultraviolet, visible and near infrared wavelengths. And the heat flux of the structure was significantly enhanced. As such, we believe that these bio-inspired hierarchical silicon structure will have promising applications in photovoltaics, sensor technology and photonic crystal devices.

Fabrication of high aspect ratio structure and its releasing for silicon on insulator MEMS/MOEMS device application

NASA Astrophysics Data System (ADS)

Fan, Ji; Zhang, Wen Ting; Liu, Jin Quan; Wu, Wen Jie; Zhu, Tao; Tu, Liang Cheng

2015-04-01

We systematically investigate the fabrication and dry-release technology for a high aspect ratio (HAR) structure with vertical and smooth silicon etching sidewalls. One-hundred-micrometer silicon on insulator (SOI) wafers are used in this work. By optimizing the process parameters of inductively coupled plasma deep reactive-ion etching, a HAR (˜25∶1) structure with a microtrench width of 4 μm has been demonstrated. A perfect etching profile has been obtained in which the structures present an almost perfect verticality of 0.10 μm and no sidewall scallops. The root-mean square roughness of silicon sidewalls is 20 to 29 nm. An in situ dry-release method using notching effect is employed after etching. By analysis, we found that the final notch length is typically an aspect-ratio-dependent process. The structure designed in this work has been successfully released by this in situ dry-release method, and the released bottom roughness effectively prohibits the stiction mechanism. The results demonstrate potential applications for design and fabrication of HAR SOI MEMS/MOEMS.

Rational Synthesis of Hollow Prussian Blue Analogue Through Coordination Replication and Controlled-Etching for Cs-Ion Removal.

PubMed

Xu, Jun; Bu, Fan-Xing; Guo, Yi-Fei; Zhang, Wei; Hu, Ming; Jiang, Ji-Sen

2018-05-01

Radioactive cesium pollution have received considerable attention due to the increasing risks in development of the nuclear power plants in the world. Although various functional porous materials are utilized to adsorb Cs+ ions in water, Prussian blue analogues (PBAs) are an impressive class of candidates because of their super affinity of Cs+ ions. The adsorption ability of the PBAs strongly relate to the mesostructure and interstitial sites. To design a hollow PBA with large number of interstitial sites, the traditional hollowing methods are not suitable owing to the difficulty in processing the specific PBAs with large number of interstitial sites. In this work, we empolyed a rational strategy which was to form a "metal oxide"@"PBA" core-shell structure via coordination replication at first, then utilized a mild etching to remove the metal oxide core, led to hollow PBA finally. The obtained hollow PBAs were of high crystallinity and large number of interstitial sites, showing a super adsorption performance for Cs+ ions (221.6 mg/g) within a short period (10 min).

Fluorescence turn-on sensing of trace cadmium ions based on EDTA-etched CdTe@CdS quantum dot.

PubMed

Wang, Si-Nan; Zhu, Jian; Li, Xin; Li, Jian-Jun; Zhao, Jun-Wu

2018-05-01

Cadmium-caused environmental pollution and diseases have always been worldwide problems. Thus it is extremely urgent to establish a cheap, rapid, simple and selective detection method for trace cadmium in drinking water. In this study, a fluorescence "turn-on" method based on ethylene diamine tetraacetic acid (EDTA)-etched CdTe@CdS quantum dots (QDs) was designed to detect Cd 2+ . High resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) were utilized for chemical and structural characterization of the as-prepared QDs. Based on chemical etching of EDTA on the surface of CdTe@CdS QDs, specific Cd 2+ recognition sites were produced, and then results in fluorescence quenching. The introduction of Cd 2+ could identify these sites and restore the fluorescence of the EDTA-QDs system. Under the optimum conditions, the nanoprobe shows a linear response range from 0.05 to 9 μM with a very low detection limit of 0.032 μM. In addition, the reported fluorescence probe in this work displays a good selectivity for trace Cd 2+ over other metal ions and an admirable practicability in real water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Stimulus responsive hydrogel-coated etched fiber Bragg grating for carcinogenic chromium (VI) sensing

NASA Astrophysics Data System (ADS)

Kishore, Pabbisetti Vayu Nandana; Madhuvarasu, Sai Shankar; Moru, Satyanarayana

2018-01-01

This paper proposes a chemo-mechanical-optical sensing approach for the detection of carcinogenic chromium (VI) metal ion using an etched fiber Bragg grating (FBG) coated with stimulus responsive hydrogel. Hydrogel synthesized from the blends of (3-acrylamidopropyl)-trimethylammonium chloride, which is highly responsive to chromium ions suffers a volume change when placed in Cr solution. When the proposed sensor system is exposed to various concentrations of Cr (VI) ion solution, FBG peak shifts due to the mechanical strain induced by the swelling of the hydrogel. The peak shift is correlated with the concentration of the Cr (VI) metal ion. Due to the reduction in the cladding diameter of FBG, wastage of swelling force due to hydrogel on FBG is lowered and utilized for more wavelength peak shift of FBG resulting in the increase in the sensitivity. The resolution of the sensor system is found to be 0.072 ppb. Trace amounts of chromium (VI) ion as low as 10 ppb can be sensed by this method. The sensor has shown good sensitivity, selectivity, and repeatability. The salient features of the sensors are its compact size, light weight, and adoptability for remote monitoring.

Cyclic photochemical re-growth of gold nanoparticles: Overcoming the mask-erosion limit during reactive ion etching on the nanoscale

PubMed Central

Seidenstücker, Axel; Plettl, Alfred; Ziemann, Paul

2013-01-01

Summary The basic idea of using hexagonally ordered arrays of Au nanoparticles (NP) on top of a given substrate as a mask for the subsequent anisotropic etching in order to fabricate correspondingly ordered arrays of nanopillars meets two serious obstacles: The position of the NP may change during the etching process and, thus, the primary pattern of the mask deteriorates or is completely lost. Furthermore, the NP are significantly eroded during etching and, consequently, the achievable pillar height is strongly restricted. The present work presents approaches on how to get around both problems. For this purpose, arrays of Au NPs (starting diameter 12 nm) are deposited on top of silica substrates by applying diblock copolymer micelle nanolithography (BCML). It is demonstrated that evaporated octadecyltrimethoxysilane (OTMS) layers act as stabilizer on the NP position, which allows for an increase of their size up to 50 nm by an electroless photochemical process. In this way, ordered arrays of silica nanopillars are obtained with maximum heights of 270 nm and aspect ratios of 5:1. Alternatively, the NP position can be fixed by a short etching step with negligible mask erosion followed by cycles of growing and reactive ion etching (RIE). In that case, each cycle is started by photochemically re-growing the Au NP mask and thereby completely compensating for the erosion due to the previous cycle. As a result of this mask repair method, arrays of silica nanopillar with heights up to 680 nm and aspect ratios of 10:1 are fabricated. Based on the given recipes, the approach can be applied to a variety of materials like silicon, silicon oxide, and silicon nitride. PMID:24367758

Response of CR-39 to 0.9-2.5 MeV protons for KOH and NaOH etching solutions

NASA Astrophysics Data System (ADS)

Bahrami, F.; Mianji, F.; Faghihi, R.; Taheri, M.; Ansarinejad, A.

2016-03-01

In some circumstances passive detecting methods are the only or preferable measuring approaches. For instance, defining particles' energy profile inside the objects being irradiated with heavy ions and measuring fluence of neutrons or heavy particles in space missions are the cases covered by these methods. In this paper the ability of polyallyl diglycol carbonate (PADC) track detector (commercially known as CR-39) for passive spectrometry of proton particles is studied. Furthermore, the effect of KOH and NaOH as commonly used chemical etching solutions on the response of the detector is investigated. The experiments were carried out with protons in the energy range of 0.94-2.5 MeV generated by a Van de Graaff accelerator. Then, the exposed track dosimeters were etched in the two aforementioned etchants through similar procedure with the same normality of 6.25 N and the same temperature of 85 °C. Formation of the tracks was precisely investigated and the track diameters were recorded following every etching step for each solution using a multistage etching process. The results showed that the proposed method can be efficiently used for the spectrometry of protons over a wider dynamic range and with a reasonable accuracy. Moreover, NaOH and KOH outperformed each other over different regions of the proton energy range. The detection efficiency of both etchants was approximately 100%.

Mechanical and chemical effects of ion-texturing biomedical polymers

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Cenkus, M. A.

1979-01-01

To determine whether sputter etching may provide substantial polymer surface texturing with insignificant changes in chemical and mechanical properties, an 8 cm beam diameter, electron bombardment, argon ion source was used to sputter etch (ion-texture process) nine biomedical polymers. The materials included silicone rubber, 32% carbon impregnated polyolefin, polyoxymethylene, polytetrafluoroethylene, ultrahigh molecular weight (UHMW) polyethylene, UHMW polyethylene with carbon fibers (10%), and several polyurethanes (bioelectric, segmented, and cross linked). Ion textured microtensile specimens of each material except UHMW polyethylene and UHMW polyethylene with 10% carbon fibers were used to determine the effect of ion texturing on tensile properties. Scanning electron microscopy was used to determine surface morphology changes, and electron spectroscopy for chemical analysis was used to analyze the near surface chemical changes that result from ion texturing. Ion energies of 500 eV with beam current densities ranging from 0.08 to 0.19 mA/sq cm were used to ion texture the various materials. Standard microtensile specimens of seven polymers were exposed to a saline environment for 24 hours prior to and during the tensile testing. The surface chemical changes resulting from sputter etching are minimal in spite of the often significant changes in the surface morphology.

Preparation of composite micro/nano structure on the silicon surface by reactive ion etching: Enhanced anti-reflective and hydrophobic properties

NASA Astrophysics Data System (ADS)

Zeng, Yu; Fan, Xiaoli; Chen, Jiajia; He, Siyu; Yi, Zao; Ye, Xin; Yi, Yougen

2018-05-01

A silicon substrate with micro-pyramid structure (black silicon) is prepared by wet chemical etching and then subjected to reactive ion etching (RIE) in the mixed gas condition of SF6, CHF3 and He. We systematically study the impacts of flow rates of SF6, CHF3 and He, the etching pressure and the etching time on the surface morphology and reflectivity through various characterizations. Meanwhile, we explore and obtain the optimal combination of parameters for the preparation of composite structure that match the RIE process based on the basis of micro-pyramid silicon substrate. The composite sample prepared under the optimum parameters exhibits excellent anti-reflective performance, hydrophobic, self-cleaning and anti-corrosive properties. Based on the above characteristics, the composite micro/nano structure can be applied to solar cells, photodetectors, LEDs, outdoor devices and other important fields.

Method for fabricating high aspect ratio structures in perovskite material

DOEpatents

Karapetrov, Goran T.; Kwok, Wai-Kwong; Crabtree, George W.; Iavarone, Maria

2003-10-28

A method of fabricating high aspect ratio ceramic structures in which a selected portion of perovskite or perovskite-like crystalline material is exposed to a high energy ion beam for a time sufficient to cause the crystalline material contacted by the ion beam to have substantially parallel columnar defects. Then selected portions of the material having substantially parallel columnar defects are etched leaving material with and without substantially parallel columnar defects in a predetermined shape having high aspect ratios of not less than 2 to 1. Etching is accomplished by optical or PMMA lithography. There is also disclosed a structure of a ceramic which is superconducting at a temperature in the range of from about 10.degree. K. to about 90.degree. K. with substantially parallel columnar defects in which the smallest lateral dimension of the structure is less than about 5 microns, and the thickness of the structure is greater than 2 times the smallest lateral dimension of the structure.

Etching and structure changes in PMMA coating under argon plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Kondyurin, Alexey; Bilek, Marcela

2011-06-01

A thin (120 nm) polymethylmethacrylate coating was treated by plasma immersion ion implantation with Ar using pulsed bias at 20 kV. Ellipsometry and FTIR spectroscopy and gel-fraction formation were used to detect the structure transformations as a function of ion fluence. The kinetics of etching, variations in refractive index and extinction coefficient in 400-1000 nm of wavelength, concentration changes in carbonyl, ether, methyl and methylene groups all as a function of ion fluence were analyzed. A critical ion fluence of 10 15 ions/cm 2 was observed to be a border between competing depolymerization and carbonization processes. Chemical reactions responsible for reorganization of the PMMA chemical structure under ion beam treatment are proposed.

Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

DOEpatents

Li, Ting [Ventura, CA

2011-04-26

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

Cryogenic rf test of the first SRF cavity etched in an rf Ar/Cl2 plasma

NASA Astrophysics Data System (ADS)

Upadhyay, J.; Palczewski, A.; Popović, S.; Valente-Feliciano, A.-M.; Im, Do; Phillips, H. L.; Vušković, L.

2017-12-01

An apparatus and a method for etching of the inner surfaces of superconducting radio frequency (SRF) accelerator cavities are described. The apparatus is based on the reactive ion etching performed in an Ar/Cl2 cylindrical capacitive discharge with reversed asymmetry. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity was used. The single cell cavity was mechanically polished and buffer chemically etched and then rf tested at cryogenic temperatures to provide a baseline characterization. The cavity's inner wall was then exposed to the capacitive discharge in a mixture of Argon and Chlorine. The inner wall acted as the grounded electrode, while kept at elevated temperature. The processing was accomplished by axially moving the dc-biased, corrugated inner electrode and the gas flow inlet in a step-wise manner to establish a sequence of longitudinally segmented discharges. The cavity was then tested in a standard vertical test stand at cryogenic temperatures. The rf tests and surface condition results, including the electron field emission elimination, are presented.

Micro-PIXE and micro-RBS characterization of micropores in porous silicon prepared using microwave-assisted hydrofluoric acid etching.

PubMed

Ahmad, Muthanna; Grime, Geoffrey W

2013-04-01

Porous silicon (PS) has been prepared using a microwave-assisted hydrofluoric acid (HF) etching method from a silicon wafer pre-implanted with 5 MeV Cu ions. The use of microbeam proton-induced X-ray emission (micro-PIXE) and microbeam Rutherford backscattering techniques reveals for the first time the capability of these techniques for studying the formation of micropores. The porous structures observed from micro-PIXE imaging results are compared to scanning electron microscope images. It was observed that the implanted copper accumulates in the same location as the pores and that at high implanted dose the pores form large-scale patterns of lines and concentric circles. This is the first work demonstrating the use of microwave-assisted HF etching in the formation of PS.

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

PubMed

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

Tridimensional morphology and kinetics of etch pit on the {l_brace}0 0 0 1{r_brace} plane of sapphire crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Lunyong; Sun Jianfei, E-mail: jfsun_hit@263.net; Zuo Hongbo

2012-08-15

The tridimensional morphology and etching kinetics of the etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal ({alpha}-Al{sub 2}O{sub 3}) in molten KOH were studied experimentally. It was shown that the etch pit takes on tridimensional morphologies with triangular symmetry same as the symmetric property of the sapphire crystal. Pits like centric and eccentric triangular pyramid as well as hexagonal pyramid were observed, but the latter is less in density. In-depth analyses show the side walls of the etch pits belong to the {l_brace}1 1{sup Macron} 0 2{sup Macron }{r_brace} family, and the triangular pit contains edgesmore » full composed by Al{sup 3+} ions on the etching surface so it is more stable than the hexagonal pit since its edges on the etching surface contains Al{sup 2+} ions. The etch pits developed in a manner of kinematic wave by the step moving with constant speed, which is controlled by the chemical reaction with activation energy of 96.6 kJ/mol between Al{sub 2}O{sub 3} and KOH. - Graphical abstract: Schematic showing the atomic configuration of the predicted side walls of regular triangular pyramid shaped etch pit on the C-{l_brace}0 0 0 1{r_brace} plane of sapphire crystal. Highlights: Black-Right-Pointing-Pointer Observed the tridimensional morphology of etch pits. Black-Right-Pointing-Pointer Figured out the atomic configuration origin of the etch pits. Black-Right-Pointing-Pointer Quantitatively determined the etch rates of the etch pits.« less

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.

Recovery of Multilayer-Coated Zerodur and ULE Optics for Extreme-Ultraviolet Lithography by Recoating, Reactive-Ion Etching, and Wet-Chemical Processes.

PubMed

Mirkarimi, P B; Baker, S L; Montcalm, C; Folta, J A

2001-01-01

Extreme-ultraviolet lithography requires expensive multilayer-coated Zerodur or ULE optics with extremely tight figure and finish specifications. Therefore it is desirable to develop methods to recover these optics if they are coated with a nonoptimum multilayer films or in the event that the coating deteriorates over time owing to long-term exposure to radiation, corrosion, or surface contamination. We evaluate recoating, reactive-ion etching, and wet-chemical techniques for the recovery of Mo/Si and Mo/Be multilayer films upon Zerodur and ULE test optics. The recoating technique was successfully employed in the recovery of Mo/Si-coated optics but has the drawback of limited applicability. A chlorine-based reactive-ion etch process was successfully used to recover Mo/Si-coated optics, and a particularly large process window was observed when ULE optics were employed; this is an advantageous for large, curved optics. Dilute HCl wet-chemical techniques were developed and successfully demonstrated for the recovery of Mo/Be-coated optics as well as for Mo/Si-coated optics when Mo/Be release layers were employed; however, there are questions about the extendability of the HCl process to large optics and multiple coat and strip cycles. The technique of using carbon barrier layers to protect the optic during removal of Mo/Si in HF:HNO(3) also showed promise.

Feature Profile Evolution of SiO2 Trenches In Fluorocarbon Plasmas

NASA Technical Reports Server (NTRS)

Hwang, Helen; Govindan, T. R.; Meyyappan, M.; Arunachalam, Valli; Rauf, Shahid; Coronell, Dan; Carroll, Carol W. (Technical Monitor)

1999-01-01

Etching of silicon microstructures for semiconductor manufacturing in chlorine plasmas has been well characterized. The etching proceeds in a two-part process, where the chlorine neutrals passivate the Si surface and then the ions etch away SiClx. However, etching in more complicated gas mixtures and materials, such as etching of SiO2 in Ar/C4F8, requires knowledge of the ion and neutral distribution functions as a function of angle and velocity, in addition to modeling the gas surface reactions. In order to address these needs, we have developed and integrated a suite of models to simulate the etching process from the plasma reactor level to the feature profile evolution level. This arrangement allows for a better understanding, control, and prediction of the influence of equipment level process parameters on feature profile evolution. We are currently using the HPEM (Hybrid Plasma Equipment Model) and PCMCM (Plasma Chemistry Monte Carlo Model) to generate plasma properties and ion and neutral distribution functions for argon/fluorocarbon discharges in a GEC Reference Cell. These quantities are then input to the feature scale model, Simulation of Profile Evolution by Level Sets (SPELS). A surface chemistry model is used to determine the interaction of the incoming species with the substrate material and simulate the evolution of the trench profile. The impact of change of gas pressure and inductive power on the relative flux of CFx and F to the wafer, the etch and polymerization rates, and feature profiles will be examined. Comparisons to experimental profiles will also be presented.

Mass spectrometry analysis of etch products from CR-39 plastic irradiated by heavy ions

NASA Astrophysics Data System (ADS)

Kodaira, S.; Nanjo, D.; Kawashima, H.; Yasuda, N.; Konishi, T.; Kurano, M.; Kitamura, H.; Uchihori, Y.; Naka, S.; Ota, S.; Ideguchi, Y.; Hasebe, N.; Mori, Y.; Yamauchi, T.

2012-09-01

As a feasibility study, gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) have been applied to analyze etch products of CR-39 plastic (one of the most frequently used solid states nuclear track detector) for the understanding of track formation and etching mechanisms by heavy ion irradiation. The etch products of irradiated CR-39 dissolved in sodium hydroxide solution (NaOH) contain radiation-induced fragments. For the GC-MS analysis, we found peaks of diethylene glycol (DEG) and a small but a definitive peak of ethylene glycol (EG) in the etch products from CR-39 irradiated by 60 MeV N ion beams. The etch products of unirradiated CR-39 showed a clear peak of DEG, but no other significant peaks were found. DEG is known to be released from the CR-39 molecule as a fragment by alkaline hydrolysis reaction of the polymer. We postulate that EG was formed as a result of the breaking of the ether bond (C-O-C) of the DEG part of the CR-39 polymer by the irradiation. The mass distribution of polyallylalcohol was obtained from the etch products from irradiated and unirradiated CR-39 samples by MALDI-MS analysis. Polyallylalcohol, with the repeating mass interval of m/z = 58 Da (dalton) between m/z = 800 and 3500, was expected to be produced from CR-39 by alkaline hydrolysis. We used IAA as a matrix to assist the ionization of organic analyte in MALDI-MS analysis and found that peaks from IAA covered mass spectrum in the lower m/z region making difficult to identify CR-39 fragment peaks which were also be seen in the same region. The mass spectrometry analysis using GC-MS and MALDI-MS will be powerful tools to investigate the radiation-induced polymeric fragments and helping to understand the track formation mechanism in CR-39 by heavy ions.

Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

PubMed

Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

2011-11-01

A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission. © 2011 American Institute of Physics

Enhanced electrochemical etching of ion irradiated silicon by localized amorphization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dang, Z. Y.; Breese, M. B. H.; Lin, Y.

2014-05-12

A tailored distribution of ion induced defects in p-type silicon allows subsequent electrochemical anodization to be modified in various ways. Here we describe how a low level of lattice amorphization induced by ion irradiation influences anodization. First, it superposes a chemical etching effect, which is observable at high fluences as a reduced height of a micromachined component. Second, at lower fluences, it greatly enhances electrochemical anodization by allowing a hole diffusion current to flow to the exposed surface. We present an anodization model, which explains all observed effects produced by light ions such as helium and heavy ions such asmore » cesium over a wide range of fluences and irradiation geometries.« less

Spectral artefacts post sputter-etching and how to cope with them - A case study of XPS on nitride-based coatings using monoatomic and cluster ion beams

NASA Astrophysics Data System (ADS)

Lewin, Erik; Counsell, Jonathan; Patscheider, Jörg

2018-06-01

The issue of artefacts due to sputter-etching has been investigated for a group of AlN-based thin film materials with varying thermodynamical stability. Stability of the materials was controlled by alloying AlN with the group 14 elements Si, Ge or Sn in two different concentrations. The coatings were sputter-etched with monoatomic Ar+ with energies between 0.2 and 4.0 keV to study the sensitivity of the materials for sputter damage. The use of Arn+ clusters to remove an oxidised surface layer was also evaluated for a selected sample. The spectra were compared to pristine spectra obtained after in-vacuo sample transfer from the synthesis chamber to the analysis instrument. It was found that the all samples were affected by high energy (4 keV) Ar+ ions to varying degrees. The determining factors for the amount of observed damage were found to be the materials' enthalpy of formation, where a threshold value seems to exist at approximately -1.25 eV/atom (∼-120 kJ/mol atoms). For each sample, the observed amount of damage was found to have a linear dependence to the energy deposited by the ion beam per volume removed material. Despite the occurrence of sputter-damage in all samples, etching settings that result in almost artefact-free spectral data were found; using either very low energy (i.e. 200 eV) monoatomic ions, or an appropriate combination of ion cluster size and energy. The present study underlines that analysis post sputter-etching must be carried out with an awareness of possible sputter-induced artefacts.

FIB Secondary Etching Method for Fabrication of Fine CNT Forest Metamaterials

NASA Astrophysics Data System (ADS)

Pander, Adam; Hatta, Akimitsu; Furuta, Hiroshi

2017-10-01

Anisotropic materials, like carbon nanotubes (CNTs), are the perfect substitutes to overcome the limitations of conventional metamaterials; however, the successful fabrication of CNT forest metamaterial structures is still very challenging. In this study, a new method utilizing a focused ion beam (FIB) with additional secondary etching is presented, which can obtain uniform and fine patterning of CNT forest nanostructures for metamaterials and ranging in sizes from hundreds of nanometers to several micrometers. The influence of the FIB processing parameters on the morphology of the catalyst surface and the growth of the CNT forest was investigated, including the removal of redeposited material, decreasing the average surface roughness (from 0.45 to 0.15 nm), and a decrease in the thickness of the Fe catalyst. The results showed that the combination of FIB patterning and secondary etching enabled the growth of highly aligned, high-density CNT forest metamaterials. The improvement in the quality of single-walled CNTs (SWNTs), defined by the very high G/D peak ratio intensity of 10.47, demonstrated successful fine patterning of CNT forest for the first time. With a FIB patterning depth of 10 nm and a secondary etching of 0.5 nm, a minimum size of 150 nm of CNT forest metamaterials was achieved. The development of the FIB secondary etching method enabled for the first time, the fabrication of SWNT forest metamaterials for the optical and infrared regime, for future applications, e.g., in superlenses, antennas, or thermal metamaterials.

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.

Fabrication of plasmonic cavity arrays for SERS analysis

NASA Astrophysics Data System (ADS)

Li, Ning; Feng, Lei; Teng, Fei; Lu, Nan

2017-05-01

The plasmonic cavity arrays are ideal substrates for surface enhanced Raman scattering analysis because they can provide hot spots with large volume for analyte molecules. The large area increases the probability to make more analyte molecules on hot spots and leads to a high reproducibility. Therefore, to develop a simple method for creating cavity arrays is important. Herein, we demonstrate how to fabricate a V and W shape cavity arrays by a simple method based on self-assembly. Briefly, the V and W shape cavity arrays are respectively fabricated by taking KOH etching on a nanohole and a nanoring array patterned silicon (Si) slides. The nanohole array is generated by taking a reactive ion etching on a Si slide assembled with monolayer of polystyrene (PS) spheres. The nanoring array is generated by taking a reactive ion etching on a Si slide covered with a monolayer of octadecyltrichlorosilane before self-assembling PS spheres. Both plasmonic V and W cavity arrays can provide large hot area, which increases the probability for analyte molecules to deposit on the hot spots. Taking 4-Mercaptopyridine as analyte probe, the enhancement factor can reach 2.99 × 105 and 9.97 × 105 for plasmonic V cavity and W cavity array, respectively. The relative standard deviations of the plasmonic V and W cavity arrays are 6.5% and 10.2% respectively according to the spectra collected on 20 random spots.

Fabrication of plasmonic cavity arrays for SERS analysis.

PubMed

Li, Ning; Feng, Lei; Teng, Fei; Lu, Nan

2017-05-05

The plasmonic cavity arrays are ideal substrates for surface enhanced Raman scattering analysis because they can provide hot spots with large volume for analyte molecules. The large area increases the probability to make more analyte molecules on hot spots and leads to a high reproducibility. Therefore, to develop a simple method for creating cavity arrays is important. Herein, we demonstrate how to fabricate a V and W shape cavity arrays by a simple method based on self-assembly. Briefly, the V and W shape cavity arrays are respectively fabricated by taking KOH etching on a nanohole and a nanoring array patterned silicon (Si) slides. The nanohole array is generated by taking a reactive ion etching on a Si slide assembled with monolayer of polystyrene (PS) spheres. The nanoring array is generated by taking a reactive ion etching on a Si slide covered with a monolayer of octadecyltrichlorosilane before self-assembling PS spheres. Both plasmonic V and W cavity arrays can provide large hot area, which increases the probability for analyte molecules to deposit on the hot spots. Taking 4-Mercaptopyridine as analyte probe, the enhancement factor can reach 2.99 × 10 5 and 9.97 × 10 5 for plasmonic V cavity and W cavity array, respectively. The relative standard deviations of the plasmonic V and W cavity arrays are 6.5% and 10.2% respectively according to the spectra collected on 20 random spots.

Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon

DTIC Science & Technology

2015-11-01

hydrogen peroxide (H2O2), and ethanol etch solution. The H2O2 reacts with hydrogen ions from the HF at the catalytic metal surface to become water...order to measure the combustion rates of the PSi, bridge wires were photolithographically deposited onto the wafers, prior to PSi etching, using a...

Fluorocarbon assisted atomic layer etching of SiO 2 and Si using cyclic Ar/C 4F 8 and Ar/CHF 3 plasma

DOE PAGES

Metzler, Dominik; Li, Chen; Engelmann, Sebastian; ...

2015-11-11

The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C 4F 8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C 4F 8 injection and synchronized plasma-based low energy Ar + ion bombardment has been established for SiO 2. 1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF 3 as a precursor is examined and compared to C 4F 8. CHF 3 is shown to enablemore » selective SiO 2/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Ting

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE processmore » is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.« less

Enhanced light absorption of solar cells and photodetectors by diffraction

DOEpatents

Zaidi, Saleem H.; Gee, James M.

2005-02-22

Enhanced light absorption of solar cells and photodetectors by diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells. Surface reflection can be tailored for either broadband, or narrow-band spectral absorption. Enhanced absorption is achieved by efficient optical coupling into obliquely propagating transmitted diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent, wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent, wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for broadband spectral absorption in solar cells and photodetectors. If reactive ion etching (RIE) processes are used to form the grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical etching treatments.

Design and fabrication of sub-wavelength anti-reflection grating

NASA Astrophysics Data System (ADS)

Zou, Wenlong; Li, Chaoming; Chen, Xinrong; Cai, Zhijian; Wu, Jianhong

2018-01-01

In the high power laser system, the reflection of optical surface has a strong impact on the efficiency for luminous energy utilization. Fresnel reflection can be effectively suppressed by antireflection film. For that, the anti-reflection film is one of the important optical elements in high power laser system. The common preparation methods of anti-reflection film include monolayer film, multilayer film and sub-wavelength grating. The effectiveness of monolayer is unsatisfactory, and its application spectrum bandwidth is very narrow. The preparation process of multilayer film is complex and it is very expensive. The emerging technology of fabrication anti-reflection film is sub-wavelength grating. The zero order transmission diffraction efficiency depends on the period, etching depth and duty cycle of the grating. The structure parameters of antireflection grating were designed and optimized under small angle incidence of 351nm based on rigorous coupled wave analysis method. The impaction of zero order reflection diffraction and zero order transmission diffraction efficiency on period, duty cycle and etching depth of grating was discussed in detail in this paper. The sub-wavelength anti-reflection grating was fabricated by holographic and ion etching method.

Making Porous Luminescent Regions In Silicon Wafers

NASA Technical Reports Server (NTRS)

Fathauer, Robert W.; Jones, Eric W.

1994-01-01

Regions damaged by ion implantation stain-etched. Porous regions within single-crystal silicon wafers fabricated by straightforward stain-etching process. Regions exhibit visible photoluminescence at room temperature and might constitute basis of novel class of optoelectronic devices. Stain-etching process has advantages over recently investigated anodic-etching process. Process works on both n-doped and p-doped silicon wafers. Related development reported in article, "Porous Si(x)Ge(1-x) Layers Within Single Crystals of Si," (NPO-18836).

Silicon-based photonic crystals fabricated using proton beam writing combined with electrochemical etching method

PubMed Central

2012-01-01

A method for fabrication of three-dimensional (3D) silicon nanostructures based on selective formation of porous silicon using ion beam irradiation of bulk p-type silicon followed by electrochemical etching is shown. It opens a route towards the fabrication of two-dimensional (2D) and 3D silicon-based photonic crystals with high flexibility and industrial compatibility. In this work, we present the fabrication of 2D photonic lattice and photonic slab structures and propose a process for the fabrication of 3D woodpile photonic crystals based on this approach. Simulated results of photonic band structures for the fabricated 2D photonic crystals show the presence of TE or TM gap in mid-infrared range. PMID:22824206

Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

PubMed Central

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

2010-01-01

This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

Surface Participation Effects in Titanium Nitride and Niobium Resonators

NASA Astrophysics Data System (ADS)

Dove, Allison; Kreikebaum, John Mark; Livingston, William; Delva, Remy; Qiu, Yanjie; Lolowang, Reinhard; Ramasesh, Vinay; O'Brien, Kevin; Siddiqi, Irfan

Improving the coherence time of superconducting qubits requires a precise understanding of the location and density of surface defects. Superconducting microwave resonators are commonly used for quantum state readout and are a versatile testbed to systematically characterize materials properties as a function of device geometry and fabrication method. We report on sputter deposited titanium nitride and niobium on silicon coplanar waveguide resonators patterned using reactive ion etches to define the device geometry. We discuss the impact of different growth conditions (temperature and electrical bias) and processing techniques on the internal quality factor (Q) of these devices. In particular, to investigate the effect of surface participation, we use a Bosch process to etch many-micron-deep trenches in the silicon substrate and quantify the impact of etch depth and profile on the internal Q. This research was supported by the ARO.

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.

Eliminating dependence of hole depth on aspect ratio by forming ammonium bromide during plasma etching of deep holes in silicon nitride and silicon dioxide

NASA Astrophysics Data System (ADS)

Iwase, Taku; Yokogawa, Kenetsu; Mori, Masahito

2018-06-01

The reaction mechanism during etching to fabricate deep holes in SiN/SiO2 stacks by using a HBr/N2/fluorocarbon-based gas plasma was investigated. To etch SiN and SiO2 films simultaneously, HBr/fluorocarbon gas mixture ratio was controlled to achieve etching selectivity closest to one. Deep holes were formed in the SiN/SiO2 stacks by one-step etching at several temperatures. The surface composition of the cross section of the holes was analyzed by time-of-flight secondary-ion mass spectrometry. It was found that bromine ions (considered to be derived from NH4Br) were detected throughout the holes in the case of low-temperature etching. It was also found that the dependence of hole depth on aspect ratio decreases as temperature decreases, and it becomes significantly weaker at a substrate temperature of 20 °C. It is therefore concluded that the formation of NH4Br supplies the SiN/SiO2 etchant to the bottom of the holes. Such a finding will make it possible to alleviate the decrease in etching rate due to a high aspect ratio.

Self-etching ceramic primer versus hydrofluoric acid etching: Etching efficacy and bonding performance.

PubMed

El-Damanhoury, Hatem M; Gaintantzopoulou, Maria D

2018-01-01

This study assessed the effect of pretreatment of hybrid and glass ceramics using a self-etching primer on the shear bond strength (SBS) and surface topography, in comparison to pretreatment with hydrofluoric acid and silane. 40 rectangular discs from each ceramic material (IPS e.max CAD;EM, Vita Mark II;VM, Vita Enamic;VE), were equally divided (n=10) and assigned to one of four surface pretreatment methods; etching with 4.8% hydrofluoric acid followed by Monobond plus (HFMP), Monobond etch & prime (Ivoclar Vivadent) (MEP), No treatment (NT) as negative control and Monobond plus (Ivoclar Vivadent) with no etching (MP) as positive control. SBS of resin cement (Multilink-N, Ivoclar Vivadent) to ceramic surfaces was tested following a standard protocol. Surface roughness was evaluated using an Atomic force microscope (AFM). Surface topography and elemental analysis were analyzed using SEM/EDX. Data were analyzed with two-way analysis of variance (ANOVA) and post-hoc Bonferroni test at a significance level of α=0.05. Pretreatment with HFMP resulted in higher SBS and increased surface roughness in comparison to MEP and MP. Regardless the method of surface pretreatment, the mean SBS values of EM ceramic was significantly higher (p<0.05) than those recorded for VM and VE, except when VE was treated with MEP, where the difference was statistically insignificant. Traces of fluoride ion were detected when MEP was used with VE and VM. Under limited conditions, using MEP resulted in comparable SBS results to HFMP; meanwhile HFMP remains the gold standard for pretreatment of glass ceramics for resin-luting cementation. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Single-Run Single-Mask Inductively-Coupled-Plasma Reactive-Ion-Etching Process for Fabricating Suspended High-Aspect-Ratio Microstructures

NASA Astrophysics Data System (ADS)

Yang, Yao-Joe; Kuo, Wen-Cheng; Fan, Kuang-Chao

2006-01-01

In this work, we present a single-run single-mask (SRM) process for fabricating suspended high-aspect-ratio structures on standard silicon wafers using an inductively coupled plasma-reactive ion etching (ICP-RIE) etcher. This process eliminates extra fabrication steps which are required for structure release after trench etching. Released microstructures with 120 μm thickness are obtained by this process. The corresponding maximum aspect ratio of the trench is 28. The SRM process is an extended version of the standard process proposed by BOSCH GmbH (BOSCH process). The first step of the SRM process is a standard BOSCH process for trench etching, then a polymer layer is deposited on trench sidewalls as a protective layer for the subsequent structure-releasing step. The structure is released by dry isotropic etching after the polymer layer on the trench floor is removed. All the steps can be integrated into a single-run ICP process. Also, only one mask is required. Therefore, the process complexity and fabrication cost can be effectively reduced. Discussions on each SRM step and considerations for avoiding undesired etching of the silicon structures during the release process are also presented.

Method for electrochemical decontamination of radioactive metal

DOEpatents

Ekechukwu, Amy A [Augusta, GA

2008-06-10

A decontamination method for stripping radionuclides from the surface of stainless steel or aluminum material comprising the steps of contacting the metal with a moderately acidic carbonate/bicarbonate electrolyte solution containing sodium or potassium ions and thereafter electrolytically removing the radionuclides from the surface of the metal whereby radionuclides are caused to be stripped off of the material without corrosion or etching of the material surface.

Multi-Functional, Micro Electromechanical Silicon Carbide Accelerometer

NASA Technical Reports Server (NTRS)

Okojie, Robert S. (Inventor)

2004-01-01

A method of bulk manufacturing SiC sensors is disclosed and claimed. Materials other than SiC may be used as the substrate material. Sensors requiring that the SiC substrate be pierced are also disclosed and claimed. A process flow reversal is employed whereby the metallization is applied first before the recesses are etched into or through the wafer. Aluminum is deposited on the entire planar surface of the metallization. Photoresist is spun onto the substantially planar surface of the Aluminum which is subsequently masked (and developed and removed). Unwanted Aluminum is etched with aqueous TMAH and subsequently the metallization is dry etched. Photoresist is spun onto the still substantially planar surface of Aluminum and oxide and then masked (and developed and removed) leaving the unimidized photoresist behind. Next, ITO is applied over the still substantially planar surface of Aluminum, oxide and unimidized photoresist. Unimidized and exposed photoresist and ITO directly above it are removed with Acetone. Next, deep reactive ion etching attacks exposed oxide not protected by ITO. Finally, hot phosphoric acid removes the Al and ITO enabling wires to connect with the metallization. The back side of the SiS wafer may be also etched.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Fukutake, Naoyuki; Miyoshi, Nozomi; Takasawa, Yuya; Urakawa, Tatsuya; Gowa, Tomoko; Okamoto, Kazumasa; Oshima, Akihiro; Tagawa, Seiichi; Washio, Masakazu

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 µm and 90 nm, respectively. Their aspect ratio was about 17.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Naoyuki Fukutake,; Nozomi Miyoshi,; Yuya Takasawa,; Tatsuya Urakawa,; Tomoko Gowa,; Kazumasa Okamoto,; Akihiro Oshima,; Seiichi Tagawa,; Masakazu Washio,

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 μm and 90 nm, respectively. Their aspect ratio was about 17.

Evolution and characteristics of GaN nanowires produced via maskless reactive ion etching.

PubMed

Haab, Anna; Mikulics, Martin; Sutter, Eli; Jin, Jiehong; Stoica, Toma; Kardynal, Beata; Rieger, Torsten; Grützmacher, Detlev; Hardtdegen, Hilde

2014-06-27

The formation of nanowires (NWs) by reactive ion etching (RIE) of maskless GaN layers was investigated. The morphological, structural and optical characteristics of the NWs were studied and compared to those of the layer they evolve from. It is shown that the NWs are the result of a defect selective etching process. The evolution of density and length with etching time is discussed. Densely packed NWs with a length of more than 1 μm and a diameter of ∼60 nm were obtained by RIE of a ∼2.5 μm thick GaN layer. The NWs are predominantly free of threading dislocations and show an improvement of optical properties compared to their layer counterpart. The production of NWs via a top down process on non-masked group III-nitride layers is assessed to be very promising for photovoltaic applications.

Formation of broadband antireflective and superhydrophilic subwavelength structures on fused silica using one-step self-masking reactive ion etching

PubMed Central

Ye, Xin; Jiang, Xiaodong; Huang, Jin; Geng, Feng; Sun, Laixi; Zu, Xiaotao; Wu, Weidong; Zheng, Wanguo

2015-01-01

Fused silica subwavelength structures (SWSs) with an average period of ~100 nm were fabricated using an efficient approach based on one-step self-masking reactive ion etching. The subwavelength structures exhibited excellent broadband antireflection properties from the ultraviolet to near-infrared wavelength range. These properties are attributable to the graded refractive index for the transition from air to the fused silica substrate that is produced by the ideal nanocone subwavelength structures. The transmittance in the 400–700 nm range increased from approximately 93% for the polished fused silica to greater than 99% for the subwavelength structure layer on fused silica. Achieving broadband antireflection in the visible and near-infrared wavelength range by appropriate matching of the SWS heights on the front and back sides of the fused silica is a novel strategy. The measured antireflection properties are consistent with the results of theoretical analysis using a finite-difference time-domain (FDTD) method. This method is also applicable to diffraction grating fabrication. Moreover, the surface of the subwavelength structures exhibits significant superhydrophilic properties. PMID:26268896

Tapered optical fiber tip probes based on focused ion beam-milled Fabry-Perot microcavities

NASA Astrophysics Data System (ADS)

André, Ricardo M.; Warren-Smith, Stephen C.; Becker, Martin; Dellith, Jan; Rothhardt, Manfred; Zibaii, M. I.; Latifi, H.; Marques, Manuel B.; Bartelt, Hartmut; Frazão, Orlando

2016-09-01

Focused ion beam technology is combined with dynamic chemical etching to create microcavities in tapered optical fiber tips, resulting in fiber probes for temperature and refractive index sensing. Dynamic chemical etching uses hydrofluoric acid and a syringe pump to etch standard optical fibers into cone structures called tapered fiber tips where the length, shape, and cone angle can be precisely controlled. On these tips, focused ion beam is used to mill several different types of Fabry-Perot microcavities. Two main cavity types are initially compared and then combined to form a third, complex cavity structure. In the first case, a gap is milled on the tapered fiber tip which allows the external medium to penetrate the light guiding region and thus presents sensitivity to external refractive index changes. In the second, two slots that function as mirrors are milled on the tip creating a silica cavity that is only sensitive to temperature changes. Finally, both cavities are combined on a single tapered fiber tip, resulting in a multi-cavity structure capable of discriminating between temperature and refractive index variations. This dual characterization is performed with the aid of a fast Fourier transform method to separate the contributions of each cavity and thus of temperature and refractive index. Ultimately, a tapered optical fiber tip probe with sub-standard dimensions containing a multi-cavity structure is projected, fabricated, characterized and applied as a sensing element for simultaneous temperature and refractive index discrimination.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzler, Dominik; Li, Chen; Engelmann, Sebastian

The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C 4F 8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C 4F 8 injection and synchronized plasma-based low energy Ar + ion bombardment has been established for SiO 2. 1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF 3 as a precursor is examined and compared to C 4F 8. CHF 3 is shown to enablemore » selective SiO 2/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

Influence of phosphoproteins' biomimetic analogs on remineralization of mineral-depleted resin-dentin interfaces created with ion-releasing resin-based systems.

PubMed

Sauro, Salvatore; Osorio, Raquel; Watson, Timothy F; Toledano, Manuel

2015-07-01

The study aimed at evaluating the remineralization of acid-etched dentin pre-treated with primers containing biomimetic analogs and bonded using an ion-releasing light-curable resin-based material. An experimental etch-and-rinse adhesive system filled with Ca(2+), PO4(3-)-releasing Ca-Silicate micro-fillers was created along with two experimental primers containing biomimetic analogs such as sodium trimetaphosphate (TMP) and/or polyaspartic acid (PLA). Dentin specimens etched with 37% H3PO4 were pre-treated with two different aqueous primers containing the polyanionic biomimetic analogs or deionized water and subsequently bonded using the experimental resin-based materials. The specimens were sectioned and analyzed by AFM/nanoindentation to evaluate changes in the modulus of elasticity (Ei) across the resin-dentin interface at different AS storage periods (up to 90 days). Raman cluster analysis was also performed to evaluate the chemical changes along the interface. The phosphate uptake by the acid-etched dentin was evaluated using the ATR-FTIR. Additional resin-dentin specimens were tested for microtensile bond strength. SEM examination was performed after de-bonding, while confocal laser microscopy was used to evaluate the interfaces ultramorphology and micropermeability. Both biomimetic primers induced phosphate uptake by acid-etched dentin. Specimens created with the ion-releasing resin in combination with the pre-treatment primers containing either PLA and TMA showed the greatest recovery of the Ei of the hybrid layer, with no decrease in μTBS (p>0.05) after 3-month AS storage. The ion-releasing resin applied after use of the biomimetic primers showed the greatest reduction in micropermeability due to mineral precipitation; these results were confirmed using SEM. The use of the ion-releasing resin-based system applied to acid-etched dentin pre-treated with biomimetic primers containing analogs of phosphoproteins such as poly-l-aspartic acid and/or sodium trimetaphosphate provides a suitable bonding approach for biomimetic remineralization of resin-dentin interfaces. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A simple and rapid method for high-resolution visualization of single-ion tracks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omichi, Masaaki; Center for Collaborative Research, Anan National College of Technology, Anan, Tokushima 774-0017; Choi, Wookjin

2014-11-15

Prompt determination of spatial points of single-ion tracks plays a key role in high-energy particle induced-cancer therapy and gene/plant mutations. In this study, a simple method for the high-resolution visualization of single-ion tracks without etching was developed through the use of polyacrylic acid (PAA)-N, N’-methylene bisacrylamide (MBAAm) blend films. One of the steps of the proposed method includes exposure of the irradiated films to water vapor for several minutes. Water vapor was found to promote the cross-linking reaction of PAA and MBAAm to form a bulky cross-linked structure; the ion-track scars were detectable at a nanometer scale by atomic forcemore » microscopy. This study demonstrated that each scar is easily distinguishable, and the amount of generated radicals of the ion tracks can be estimated by measuring the height of the scars, even in highly dense ion tracks. This method is suitable for the visualization of the penumbra region in a single-ion track with a high spatial resolution of 50 nm, which is sufficiently small to confirm that a single ion hits a cell nucleus with a size ranging between 5 and 20 μm.« less

Fabrication of a trimer/single atom tip for gas field ion sources by means of field evaporation without tip heating.

PubMed

Kim, Kwang-Il; Kim, Young Heon; Ogawa, Takashi; Choi, Suji; Cho, Boklae; Ahn, Sang Jung; Park, In-Yong

2018-05-11

A gas field ion source (GFIS) has many advantages that are suitable for ion microscope sources, such as high brightness and a small virtual source size, among others. In order to apply a tip-based GFIS to an ion microscope, it is better to create a trimer/single atom tip (TSAT), where the ion beam must be generated in several atoms of the tip apex. Here, unlike the conventional method which uses tip heating or a reactive gas, we show that the tip surface can be cleaned using only the field evaporation phenomenon and that the TSAT can also be fabricated using an insulating layer containing tungsten oxide, which remains after electrochemical etching. Using this method, we could get TSAT over 90% of yield. Copyright © 2018. Published by Elsevier B.V.

Photonic guiding structures in lithium niobate crystals produced by energetic ion beams

NASA Astrophysics Data System (ADS)

Chen, Feng

2009-10-01

A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.

Very Large Area/Volume Microwave ECR Plasma and Ion Source

NASA Technical Reports Server (NTRS)

Foster, John E. (Inventor); Patterson, Michael J. (Inventor)

2009-01-01

The present invention is an apparatus and method for producing very large area and large volume plasmas. The invention utilizes electron cyclotron resonances in conjunction with permanent magnets to produce dense, uniform plasmas for long life ion thruster applications or for plasma processing applications such as etching, deposition, ion milling and ion implantation. The large area source is at least five times larger than the 12-inch wafers being processed to date. Its rectangular shape makes it easier to accommodate to materials processing than sources that are circular in shape. The source itself represents the largest ECR ion source built to date. It is electrodeless and does not utilize electromagnets to generate the ECR magnetic circuit, nor does it make use of windows.

Development of large-surface Nafion-metal composite actuator and its electrochemical characterization

NASA Astrophysics Data System (ADS)

Noh, Taegeun; Tak, Yong Suk; Nam, Jaedo; Jeon, Jaewook; Kim, Hunmo; Choi, Hyoukryeol; Bae, Sang Sik

2001-07-01

Behaviors of nafion-based actuators are significantly affected by interfacial area between electrode and polymer electrolyte. Replication method was utilized to manufacture a large surface-area composite actuator. Etched aluminum foil was used as a template for replication using liquid nafion solution. Measurement of double layer charging and scanning electron microscopy indicated that interfacial area was greatly increased by replication method. Higher surface area induced a better bending performance of ionic polymer metal composite (IPMC). In parallel, the effect of cations on IPMC was interpreted with constant current experiment, linear sweep voltammetry and electrochemical impedance spectroscopy. For univalent cations, ion size is the most influencing parameter on ionic mobility inside membrane. However, ion-ion interaction affects an ionic mobility for divalent cations.

Prediction of silicon oxynitride plasma etching using a generalized regression neural network

NASA Astrophysics Data System (ADS)

Kim, Byungwhan; Lee, Byung Teak

2005-08-01

A prediction model of silicon oxynitride (SiON) etching was constructed using a neural network. Model prediction performance was improved by means of genetic algorithm. The etching was conducted in a C2F6 inductively coupled plasma. A 24 full factorial experiment was employed to systematically characterize parameter effects on SiON etching. The process parameters include radio frequency source power, bias power, pressure, and C2F6 flow rate. To test the appropriateness of the trained model, additional 16 experiments were conducted. For comparison, four types of statistical regression models were built. Compared to the best regression model, the optimized neural network model demonstrated an improvement of about 52%. The optimized model was used to infer etch mechanisms as a function of parameters. The pressure effect was noticeably large only as relatively large ion bombardment was maintained in the process chamber. Ion-bombardment-activated polymer deposition played the most significant role in interpreting the complex effect of bias power or C2F6 flow rate. Moreover, [CF2] was expected to be the predominant precursor to polymer deposition.

Development of Functional Surfaces on High-Density Polyethylene (HDPE) via Gas-Assisted Etching (GAE) Using Focused Ion Beams.

PubMed

Sezen, Meltem; Bakan, Feray

2015-12-01

Irradiation damage, caused by the use of beams in electron and ion microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on electron/ion beam irradiation. Nevertheless, it is possible to turn degradation-dependent physical/chemical changes from negative to positive use when materials are intentionally exposed to beams. Especially, controllable surface modification allows tuning of surface properties for targeted purposes and thus provides the use of ultimate materials and their systems at the micro/nanoscale for creating functional surfaces. In this work, XeF2 and I2 gases were used in the focused ion beam scanning electron microscope instrument in combination with gallium ion etching of high-density polyethylene surfaces with different beam currents and accordingly different gas exposure times resulting at the same ion dose to optimize and develop new polymer surface properties and to create functional polymer surfaces. Alterations in the surface morphologies and surface chemistry due to gas-assisted etching-based nanostructuring with various processing parameters were tracked using high-resolution SEM imaging, complementary energy-dispersive spectroscopic analyses, and atomic force microscopic investigations.

Chemically Etched Silicon Nanowires as Anodes for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, Hannah Elise

2015-08-01

This study focused on silicon as a high capacity replacement anode for Lithium-ion batteries. The challenge of silicon is that it expands ~270% upon lithium insertion which causes particles of silicon to fracture, causing the capacity to fade rapidly. To account for this expansion chemically etched silicon nanowires from the University of Maine were studied as anodes. They were built into electrochemical half-cells and cycled continuously to measure the capacity and capacity fade.

Nb/Al-AlOx/Nb Edge Junctions for Distributed Mixers

NASA Astrophysics Data System (ADS)

Amos, R. S.; Lichtenberger, A. W.; Tong, C. E.; Blundell, R.; Pan, S.-K.; Kerr, A. R.

We have fabricated high quality Nb/Al-oxide/Al/Nb edge junctions using a Nb/SiO/sub 2/ bi-layer film as the base electrode, suitable for use as traveling wave mixers. An edge is cut in the bi-layer with an ion gun at a 45 degree angle using a photoresist mask. The wafer is then cleaned in-situ with a physical ion gun clean followed by the deposition of a thin Al (a1) film, which is then thermally oxidized, an optional second Al (a2) layer, and a Nb counter electrode. It was found that devices with an a2 layer resulted in superior electrical characteristics, though proximity effects increased strongly with a2 thickness. The counter electrode is defined with an SF/sub 6/+N/sub 2/ reactive ion etch, using the Al barrier layer as an etch stop. The Al barrier layer is then either removed with an Al wet etch to isolate the individual devices, or the devices are separated with an anodization process. Various ion gun cleaning conditions have been examined; in addition, both wet and plasma etch bi-layer edge surface pre-treatments were investigated. It was found that edge junctions with large widths (i.e., those more suitable for traveling wave mixers) typically benefited more from such treatments. Initial receiver results at 260 GHz have yielded a DSB noise temperature of 60 K.

Sidewall patterning—a new wafer-scale method for accurate patterning of vertical silicon structures

NASA Astrophysics Data System (ADS)

Westerik, P. J.; Vijselaar, W. J. C.; Berenschot, J. W.; Tas, N. R.; Huskens, J.; Gardeniers, J. G. E.

2018-01-01

For the definition of wafer scale micro- and nanostructures, in-plane geometry is usually controlled by optical lithography. However, options for precisely patterning structures in the out-of-plane direction are much more limited. In this paper we present a versatile self-aligned technique that allows for reproducible sub-micrometer resolution local modification along vertical silicon sidewalls. Instead of optical lithography, this method makes smart use of inclined ion beam etching to selectively etch the top parts of structures, and controlled retraction of a conformal layer to define a hard mask in the vertical direction. The top, bottom or middle part of a structure could be selectively exposed, and it was shown that these exposed regions can, for example, be selectively covered with a catalyst, doped, or structured further.

Design and fabrication of a large area freestanding compressive stress SiO2 optical window

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Sangu, Suguru; Ono, Takahito

2016-07-01

This paper reports the design and fabrication of a 7.2 mm  ×  9.6 mm freestanding compressive stress SiO2 optical window without buckling. An application of the SiO2 optical window with and without liquid penetration has been demonstrated for an optical modulator and its optical characteristic is evaluated by using an image sensor. Two methods for SiO2 optical window fabrication have been presented. The first method is a combination of silicon etching and a thermal oxidation process. Silicon capillaries fabricated by deep reactive ion etching (deep RIE) are completely oxidized to form the SiO2 capillaries. The large compressive stress of the oxide causes buckling of the optical window, which is reduced by optimizing the design of the device structure. A magnetron-type RIE, which is investigated for deep SiO2 etching, is the second method. This method achieves deep SiO2 etching together with smooth surfaces, vertical shapes and a high aspect ratio. Additionally, in order to avoid a wrinkling optical window, the idea of a Peano curve structure has been proposed to achieve a freestanding compressive stress SiO2 optical window. A 7.2 mm  ×  9.6 mm optical window area without buckling integrated with an image sensor for an optical modulator has been successfully fabricated. The qualitative and quantitative evaluations have been performed in cases with and without liquid penetration.

A Macroporous TiO2 Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask

PubMed Central

Lu, Chih-Cheng; Huang, Yong-Sheng; Huang, Jun-Wei; Chang, Chien-Kuo; Wu, Sheng-Po

2010-01-01

An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO2 nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO2 chemoresistive gas sensor demonstrates 2-fold higher (∼33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors. PMID:22315561

CHARGE SPECTRUM OF HEAVY AND SUPERHEAVY COMPONENTS OF GALACTIC COSMIC RAYS: RESULTS OF THE OLIMPIYA EXPERIMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexeev, Victor; Kalinina, Galina; Pavlova, Tatyana, E-mail: aval37@mail.ru, E-mail: gakalin@mail.ru, E-mail: pavlova4tat@mail.ru

2016-10-01

The aim of the OLIMPIYA experiment is to search for and identify traces of heavy and superheavy nuclei of galactic cosmic rays (GCR) in olivine crystals from stony–iron meteorites serving as nuclear track detectors. The method is based on layer-by-layer grinding and etching of particle tracks in these crystals. Unlike the techniques of other authors, this annealing-free method uses two parameters: the etching rate along the track ( V {sub etch}) and the total track length ( L ), to identify charge Z of a projectile. A series of irradiations with different swift heavy ions at the accelerator facilities ofmore » GSI (Darmstadt) and IMP (Lanzhou) were performed in order to determine and calibrate the dependence of projectile charge on V {sub etch} and L . To date, one of the most essential results of the experiment is the obtained charge spectrum of GCR nuclei within the range of Z > 40, based on about 11.6 thousand processed tracks. As the result of data processing, 384 nuclei with charges Z ≥ 75 have been identified, including 10 nuclei identified as actinides (90 < Z < 103). Three tracks were identified to be produced by nuclei with charges 113 < Z < 129. Such nuclei may be part of the Island of Stability of transfermium elements.« less

A macroporous TiO2 oxygen sensor fabricated using anodic aluminium oxide as an etching mask.

PubMed

Lu, Chih-Cheng; Huang, Yong-Sheng; Huang, Jun-Wei; Chang, Chien-Kuo; Wu, Sheng-Po

2010-01-01

An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO(2) nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO(2) chemoresistive gas sensor demonstrates 2-fold higher (∼33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors.

More vertical etch profile using a Faraday cage in plasma etching

NASA Astrophysics Data System (ADS)

Cho, Byeong-Ok; Hwang, Sung-Wook; Ryu, Jung-Hyun; Moon, Sang Heup

1999-05-01

Scanning electron microscope images of sidewalls obtained by plasma etching of an SiO2 film with and without a Faraday cage have been compared. When the substrate film is etched in the Faraday cage, faceting is effectively suppressed and the etch profile becomes more vertical regardless of the process conditions. This is because the electric potential in the cage is nearly uniform and therefore distortion of the electric field at the convex corner of a microfeature is prevented. The most vertical etch profile is obtained when the cage is used in fluorocarbon plasmas, where faceting is further suppressed due to the decrease in the chemical sputtering yield and the increase in the radical/ion flux on the substrate.

Graphene nanoribbons: Relevance of etching process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simonet, P., E-mail: psimonet@phys.ethz.ch; Bischoff, D.; Moser, A.

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 bymore » more or larger localized states at the edges of the ashed device compared to the RIE defined device.« less

Ultraviolet Laser Damage Dependence on Contamination Concentration in Fused Silica Optics during Reactive Ion Etching Process

PubMed Central

Sun, Laixi; Shao, Ting; Shi, Zhaohua; Huang, Jin; Ye, Xin; Jiang, Xiaodong; Wu, Weidong; Yang, Liming; Zheng, Wanguo

2018-01-01

The reactive ion etching (RIE) process of fused silica is often accompanied by surface contamination, which seriously degrades the ultraviolet laser damage performance of the optics. In this study, we find that the contamination behavior on the fused silica surface is very sensitive to the RIE process which can be significantly optimized by changing the plasma generating conditions such as discharge mode, etchant gas and electrode material. Additionally, an optimized RIE process is proposed to thoroughly remove polishing-introduced contamination and efficiently prevent the introduction of other contamination during the etching process. The research demonstrates the feasibility of improving the damage performance of fused silica optics by using the RIE technique. PMID:29642571

Vertical and bevel-structured SiC etching techniques incorporating different gas mixture plasmas for various microelectronic applications.

PubMed

Sung, Ho-Kun; Qiang, Tian; Yao, Zhao; Li, Yang; Wu, Qun; Lee, Hee-Kwan; Park, Bum-Doo; Lim, Woong-Sun; Park, Kyung-Ho; Wang, Cong

2017-06-20

This study presents a detailed fabrication method, together with validation, discussion, and analysis, for state-of-the-art silicon carbide (SiC) etching of vertical and bevelled structures by using inductively coupled plasma reactive ion etching (ICP-RIE) for microelectronic applications. Applying different gas mixtures, a maximum bevel angle of 87° (almost vertical), large-angle bevels ranging from 40° to 80°, and small-angel bevels ranging from 7° to 17° were achieved separately using distinct gas mixtures at different ratios. We found that SF 6 with additive O 2 was effective for vertical etching, with a best etching rate of 3050 Å/min. As for the large-angle bevel structures, BCl 3  + N 2 gas mixtures show better characteristics, exhibiting a controllable and large etching angle range from 40° to 80° through the adjustment of the mixture ratio. Additionally, a Cl 2  + O 2 mixture at different ratios is applied to achieve a small-angel bevels ranging from 7° to 17°. A minimum bevel angel of approximately 7° was achieved under the specific volume of 2.4 sccm Cl 2 and 3.6 sccm O 2 . These results can be used to improve performance in various microelectronic applications including MMIC via holes, PIN diodes, Schottky diodes, JFETs' bevel mesa, and avalanche photodiode fabrication.

Oblique patterned etching of vertical silicon sidewalls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burckel, D. Bruce; Finnegan, Patrick S.; Henry, M. David

A method for patterning on vertical silicon surfaces in high aspect ratio silicontopography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

Oblique patterned etching of vertical silicon sidewalls

NASA Astrophysics Data System (ADS)

Bruce Burckel, D.; Finnegan, Patrick S.; David Henry, M.; Resnick, Paul J.; Jarecki, Robert L.

2016-04-01

A method for patterning on vertical silicon surfaces in high aspect ratio silicon topography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

Intrinsic bond strength of metal films on polymer substrates

NASA Technical Reports Server (NTRS)

Wheeler, Donald R.; Osaki, Hiroyuki

1990-01-01

A semiquantitative method for the measurement of the intrinsic bond strength between elastic substrates and elastic films that fail by brittle fracture is described. Measurements on a polyethylene terephthalate (PET)-Ni couple were used to verify the essential features of the analysis. It was found that the interfacial shear strength of Ni on PET doubled after ion etching.

Oblique patterned etching of vertical silicon sidewalls

DOE PAGES

Burckel, D. Bruce; Finnegan, Patrick S.; Henry, M. David; ...

2016-04-05

A method for patterning on vertical silicon surfaces in high aspect ratio silicontopography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

Sputtering yields and surface chemical modification of tin-doped indium oxide in hydrocarbon-based plasma etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hu; Karahashi, Kazuhiro; Hamaguchi, Satoshi, E-mail: hamaguch@ppl.eng.osaka-u.ac.jp

2015-11-15

Sputtering yields and surface chemical compositions of tin-doped indium oxide (or indium tin oxide, ITO) by CH{sup +}, CH{sub 3}{sup +}, and inert-gas ion (He{sup +}, Ne{sup +}, and Ar{sup +}) incidence have been obtained experimentally with the use of a mass-selected ion beam system and in-situ x-ray photoelectron spectroscopy. It has been found that etching of ITO is chemically enhanced by energetic incidence of hydrocarbon (CH{sub x}{sup +}) ions. At high incident energy incidence, it appears that carbon of incident ions predominantly reduce indium (In) of ITO and the ITO sputtering yields by CH{sup +} and CH{sub 3}{sup +}more » ions are found to be essentially equal. At lower incident energy (less than 500 eV or so), however, a hydrogen effect on ITO reduction is more pronounced and the ITO surface is more reduced by CH{sub 3}{sup +} ions than CH{sup +} ions. Although the surface is covered more with metallic In by low-energy incident CH{sub 3}{sup +} ions than CH{sup +} ions and metallic In is in general less resistant against physical sputtering than its oxide, the ITO sputtering yield by incident CH{sub 3}{sup +} ions is found to be lower than that by incident CH{sup +} ions in this energy range. A postulation to account for the relation between the observed sputtering yield and reduction of the ITO surface is also presented. The results presented here offer a better understanding of elementary surface reactions observed in reactive ion etching processes of ITO by hydrocarbon plasmas.« less

Oxygen ion-beam microlithography

DOEpatents

Tsuo, Y.S.

1991-08-20

A method of providing and developing a resist on a substrate for constructing integrated circuit (IC) chips includes the following steps: of depositing a thin film of amorphous silicon or hydrogenated amorphous silicon on the substrate and exposing portions of the amorphous silicon to low-energy oxygen ion beams to oxidize the amorphous silicon at those selected portions. The nonoxidized portions are then removed by etching with RF-excited hydrogen plasma. Components of the IC chip can then be constructed through the removed portions of the resist. The entire process can be performed in an in-line vacuum production system having several vacuum chambers. Nitrogen or carbon ion beams can also be used. 5 figures.

Oxygen ion-beam microlithography

DOEpatents

Tsuo, Y. Simon

1991-01-01

A method of providing and developing a resist on a substrate for constructing integrated circuit (IC) chips includes the following steps: of depositing a thin film of amorphous silicon or hydrogenated amorphous silicon on the substrate and exposing portions of the amorphous silicon to low-energy oxygen ion beams to oxidize the amorphous silicon at those selected portions. The nonoxidized portions are then removed by etching with RF-excited hydrogen plasma. Components of the IC chip can then be constructed through the removed portions of the resist. The entire process can be performed in an in-line vacuum production system having several vacuum chambers. Nitrogen or carbon ion beams can also be used.

Field ionization characteristics of an ion source array for neutron generators

NASA Astrophysics Data System (ADS)

Bargsten Johnson, B.; Schwoebel, P. R.; Resnick, P. J.; Holland, C. E.; Hertz, K. L.; Chichester, D. L.

2013-11-01

A new deuterium ion source is being developed to improve the performance of existing compact neutron generators. The ion source is a microfabricated array of metal tips with an integrated gate (i.e., grid) and produces deuterium ions by field ionizing (or field desorbing) a supply of deuterium gas. Deuterium field ion currents from arrays at source temperatures of 77 K and 293 K are studied. Ion currents from single etched-wire tips operating under the same conditions are used to help understand array results. I-F characteristics of the arrays were found to follow trends similar to those of the better understood single etched-wire tip results; however, the fields achieved by the arrays are limited by electrical breakdown of the structure. Neutron production by field ionization at 293 K was demonstrated for the first time from microfabricated array structures with integrated gates.

Cl 2-based dry etching of the AlGaInN system in inductively coupled plasmas

NASA Astrophysics Data System (ADS)

Cho, Hyun; Vartuli, C. B.; Abernathy, C. R.; Donovan, S. M.; Pearton, S. J.; Shul, R. J.; Han, J.

1998-12-01

Cl 2-Based inductively coupled plasmas with low additional d.c. self-biases (-100 V) produce convenient etch rates (500-1500 Å·min -1) for GaN, AlN, InN, InAlN and InGaN. A systematic study of the effects of additive gas (Ar, N 2, H 2), discharge composition and ICP source power and chuck power on etch rate and surface morphology has been performed. The general trends are to go through a maximum in etch rate with percent Cl 2 in the discharge for all three mixtures and to have an increase (decrease) in etch rate with source power (pressure). Since the etching is strongly ion-assisted, anisotropic pattern transfer is readily achieved. Maximum etch selectivities of approximately 6 for InN over the other nitrides were obtained.

Cryogenic Etching of High Aspect Ratio 400 nm Pitch Silicon Gratings.

PubMed

Miao, Houxun; Chen, Lei; Mirzaeimoghri, Mona; Kasica, Richard; Wen, Han

2016-10-01

The cryogenic process and Bosch process are two widely used processes for reactive ion etching of high aspect ratio silicon structures. This paper focuses on the cryogenic deep etching of 400 nm pitch silicon gratings with various etching mask materials including polymer, Cr, SiO 2 and Cr-on-polymer. The undercut is found to be the key factor limiting the achievable aspect ratio for the direct hard masks of Cr and SiO 2 , while the etch selectivity responds to the limitation of the polymer mask. The Cr-on-polymer mask provides the same high selectivity as Cr and reduces the excessive undercut introduced by direct hard masks. By optimizing the etching parameters, we etched a 400 nm pitch grating to ≈ 10.6 μ m depth, corresponding to an aspect ratio of ≈ 53.

Research on subsurface deformed layer in ultra-precision cutting of single crystal copper by focused ion beam etching method

NASA Astrophysics Data System (ADS)

Chen, Y.; Huang, X. J.; Kong, J. X.

2018-03-01

In this paper, the focused ion beam was used to study the subsurface deformed layer of single crystal copper caused by the nanoscale single-point diamond fly cutting, and the possibility of using nanometer ultra-precision cutting to remove the larger deformation layer caused by traditional rough cutting process was explored. The maximum cutting thickness of single-point diamond cutting was about 146 nm, and the surface of the single-crystal copper after cutting was etched and observed by using the focused ion beam method. It was found that the morphology of the near-surface layer and the intermediate layer of the copper material were larger differences: the near-surface of the material was smaller and more compact, and the intermediate material layer of the material was more coarse sparse. The results showed that the traditional precision cutting would residual significant subsurface deformed layer and the thickness was on micron level. Even more, the subsurface deformed layer was obviously removed from about 12μm to 5μm after single-point diamond fly cutting in this paper. This paper proved that the large-scale subsurface deformed layer caused by traditional cutting process could be removed by nanometer ultra-precision cutting. It was of great significance to further establish the method that control of the deformation of weak rigid components by reducing the depth of the subsurface deformed layers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu; Li, Chen

The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C{sub 4}F{sub 8} ALE based on steady-state Ar plasma in conjunction with periodic, precise C{sub 4}F{sub 8} injection and synchronized plasma-based low energy Ar{sup +} ion bombardment has been established for SiO{sub 2} [Metzler et al., J. Vac. Sci. Technol. A 32, 020603 (2014)]. In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF{sub 3} as a precursor is examined and comparedmore » to C{sub 4}F{sub 8}. CHF{sub 3} is shown to enable selective SiO{sub 2}/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and x-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. Plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

Holographic fabrication of gratings in metal substrates

NASA Technical Reports Server (NTRS)

Fletcher, R. M.; Wagner, D. K.; Ballantyne, J. M.

1982-01-01

A program for investigating the grain enlargement resulting from the laser recrystallization of a thin gallium arsenide film on a patterned substrate, a technique known as graphoepitaxy was evaluated. More specifically, the effects of recrystallizing an uncapped gallium arsenide film using a continuous wave neodymium YAG laser operating at 1.06 microns were studied. In an effort to minimize arsenic loss from the film, the specimens were held in an arsine atmosphere during recrystallization. Two methods for fabricating patterned substrates were developed, one using reactive ion etching of a molybdenum film on both sapphire and silicon substates and another by preferential wet etching of a silicon substrate onto which a film of molybdenum was subsequently deposited.

Simultaneous fabrication of very high aspect ratio positive nano- to milliscale structures.

PubMed

Chen, Long Qing; Chan-Park, Mary B; Zhang, Qing; Chen, Peng; Li, Chang Ming; Li, Sai

2009-05-01

A simple and inexpensive technique for the simultaneous fabrication of positive (i.e., protruding), very high aspect (>10) ratio nanostructures together with micro- or millistructures is developed. The method involves using residual patterns of thin-film over-etching (RPTO) to produce sub-micro-/nanoscale features. The residual thin-film nanopattern is used as an etching mask for Si deep reactive ion etching. The etched Si structures are further reduced in size by Si thermal oxidation to produce amorphous SiO(2), which is subsequently etched away by HF. Two arrays of positive Si nanowalls are demonstrated with this combined RPTO-SiO(2)-HF technique. One array has a feature size of 150 nm and an aspect ratio of 26.7 and another has a feature size of 50 nm and an aspect ratio of 15. No other parallel reduction technique can achieve such a very high aspect ratio for 50-nm-wide nanowalls. As a demonstration of the technique to simultaneously achieve nano- and milliscale features, a simple Si nanofluidic master mold with positive features with dimensions varying continuously from 1 mm to 200 nm and a highest aspect ratio of 6.75 is fabricated; the narrow 200-nm section is 4.5 mm long. This Si master mold is then used as a mold for UV embossing. The embossed open channels are then closed by a cover with glue bonding. A high aspect ratio is necessary to produce unblocked closed channels after the cover bonding process of the nanofluidic chip. The combined method of RPTO, Si thermal oxidation, and HF etching can be used to make complex nanofluidic systems and nano-/micro-/millistructures for diverse applications.

Formation of nanometer-size wires using infiltration into latent nuclear tracks

DOEpatents

Musket, Ronald G.; Felter, Thomas E.

2002-01-01

Nanometer-size wires having a cross-sectional dimension of less than 8 nm with controllable lengths and diameters are produced by infiltrating latent nuclear or ion tracks formed in trackable materials with atomic species. The trackable materials and atomic species are essentially insoluble in each other, thus the wires are formed by thermally driven, self-assembly of the atomic species during annealing, or re-crystallization, of the damage in the latent tracks. Unlike conventional ion track lithography, the inventive method does not require etching of the latent tracks.

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

DOE PAGES

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.; ...

2016-10-04

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

Fabrication of porous microrings via laser printing and ion-beam post-etching

NASA Astrophysics Data System (ADS)

Syubaev, S.; Nepomnyashchiy, A.; Mitsai, E.; Pustovalov, E.; Vitrik, O.; Kudryashov, S.; Kuchmizhak, A.

2017-08-01

Pulsed-laser dry printing of noble-metal microrings with a tunable internal porous structure, which can be revealed via an ion-beam etching post-procedure, was demonstrated. The abundance and average size of the pores inside the microrings were shown to be tuned in a wide range by varying the incident pulse energy and a nitrogen doping level controlled in the process of magnetron deposition of the gold film in the appropriate gaseous environment. The fabricated porous microrings were shown to provide many-fold near-field enhancement of incident electromagnetic fields, which was confirmed by mapping of the characteristic Raman band of a nanometer-thick covering layer of Rhodamine 6G dye molecules and supporting finite-difference time-domain calculations. The proposed laser-printing/ion-beam etching approach is demonstrated to be a unique tool aimed at designing and fabricating multifunctional plasmonic structures and metasurfaces for spectroscopic bioidentification based on surface-enhanced infrared absorption, Raman scattering, and photoluminescence detection schemes.

Antireflective glass nanoholes on optical lenses.

PubMed

Lee, Youngseop; Bae, Sang-In; Eom, Jaehyeon; Suh, Ho-Cheol; Jeong, Ki-Hun

2018-05-28

Antireflective structures, inspired from moth eyes, are still reserved for practical use due to their large-area nanofabrication and mechanical stability. Here we report an antireflective optical lens with large-area glass nanoholes. The nanoholes increase light transmission due to the antireflective effect, depending on geometric parameters such as fill factor and height. The glass nanoholes of low effective refractive index are achieved by using solid-state dewetting of ultrathin silver film, reactive ion etching, and wet etching. An ultrathin silver film is transformed into nanoholes for an etch mask in reactive ion etching after thermal annealing at a low temperature. Unlike conventional nanopillars, nanoholes exhibit high light transmittance with enhancement of ~4% over the full visible range as well as high mechanical hardness. Also, an antireflective glass lens is achieved by directly employing nanoholes on the lens surface. Glass nanoholes of highly enhanced optical and mechanical performance can be directly utilized for commercial glass lenses in various imaging and lighting applications.

Study of multilayered SiGe semiconductor structures by X-ray diffractometry, grazing-incidence X-ray reflectometry, and secondary-ion mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunin, P. A., E-mail: yunin@ipmras.ru; Drozdov, Yu. N.; Drozdov, M. N.

2013-12-15

In this publication, we report the results of studying a multilayerd nonperiodic SiGe/Si structure by the methods of X-ray diffractometry, grazing-angle X-ray reflectometry, and secondary-ion mass spectrometry (SIMS). Special attention is paid to the processing of the component distribution profile using the SIMS method and to consideration of the most significant experimental distortions introduced by this method. A method for processing the measured composition distribution profile with subsequent consideration of the influence of matrix effects, variation in the etching rate, and remnants of ion sputtering is suggested. The results of such processing are compared with a structure model obtained uponmore » combined analysis of X-ray diffractometry and grazing-angle reflectometry data. Good agreement between the results is established. It is shown that the combined use of independent techniques makes it possible to improve the methods of secondary-ion mass spectrometry and grazing-incidence reflectometry as applied to an analysis of multilayered heteroepitaxial structures (to increase the accuracy and informativity of these methods)« less

Ion beam applications research. A summary of Lewis Research Center Programs

NASA Technical Reports Server (NTRS)

Banks, B. A.

1981-01-01

A summary of the ion beam applications research (IBAR) program organized to enable the development of materials, products, and processes through the nonpropulsive application of ion thruster technology is given. Specific application efforts utilizing ion beam sputter etching, deposition, and texturing are discussed as well as ion source and component technology applications.

Ripple formation on Si surfaces during plasma etching in Cl2

NASA Astrophysics Data System (ADS)

Nakazaki, Nobuya; Matsumoto, Haruka; Sonobe, Soma; Hatsuse, Takumi; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2018-05-01

Nanoscale surface roughening and ripple formation in response to ion incidence angle has been investigated during inductively coupled plasma etching of Si in Cl2, using sheath control plates to achieve the off-normal ion incidence on blank substrate surfaces. The sheath control plate consisted of an array of inclined trenches, being set into place on the rf-biased electrode, where their widths and depths were chosen in such a way that the sheath edge was pushed out of the trenches. The distortion of potential distributions and the consequent deflection of ion trajectories above and in the trenches were then analyzed based on electrostatic particle-in-cell simulations of the plasma sheath, to evaluate the angular distributions of ion fluxes incident on substrates pasted on sidewalls and/or at the bottom of the trenches. Experiments showed well-defined periodic sawtooth-like ripples with their wave vector oriented parallel to the direction of ion incidence at intermediate off-normal angles, while relatively weak corrugations or ripplelike structures with the wave vector perpendicular to it at high off-normal angles. Possible mechanisms for the formation of surface ripples during plasma etching are discussed with the help of Monte Carlo simulations of plasma-surface interactions and feature profile evolution. The results indicate the possibility of providing an alternative to ion beam sputtering for self-organized formation of ordered surface nanostructures.

Surface and structure modification induced by high energy and highly charged uranium ion irradiation in monocrystal spinel

NASA Astrophysics Data System (ADS)

Yang, Yitao; Zhang, Chonghong; Song, Yin; Gou, Jie; Zhang, Liqing; Meng, Yancheng; Zhang, Hengqing; Ma, Yizhun

2014-05-01

Due to its high temperature properties and relatively good behavior under irradiation, magnesium aluminate spinel (MgAl2O4) is considered as a possible material to be used as inert matrix for the minor actinides burning. In this case, irradiation damage is an unavoidable problem. In this study, high energy and highly charged uranium ions (290 MeV U32+) were used to irradiate monocrystal spinel to the fluence of 1.0 × 1013 ions/cm2 to study the modification of surface and structure. Highly charged ions carry large potential energy, when they interact with a surface, the release of potential energy results in the modification of surface. Atomic force microscopy (AFM) results showed the occurrence of etching on surface after uranium ion irradiation. The etching depth reached 540 nm. The surprising efficiency of etching is considered to be induced by the deposition of potential energy with high density. The X-ray diffraction results showed that the (4 4 0) diffraction peak obviously broadened after irradiation, which indicated that the distortion of lattice has occurred. After multi-peak Gaussian fitting, four Gaussian peaks were separated, which implied that a structure with different damage layers could be formed after irradiation.

Nitrogen reactive ion etch processes for the selective removal of poly-(4-vinylpyridine) in block copolymer films.

PubMed

Flynn, Shauna P; Bogan, Justin; Lundy, Ross; Khalafalla, Khalafalla E; Shaw, Matthew; Rodriguez, Brian J; Swift, Paul; Daniels, Stephen; O'Connor, Robert; Hughes, Greg; Kelleher, Susan M

2018-08-31

Self-assembling block copolymer (BCP) patterns are one of the main contenders for the fabrication of nanopattern templates in next generation lithography technology. Transforming these templates to hard mark materials is key for pattern transfer and in some cases, involves selectively removing one block from the nanopattern. For poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP), a high χ BCP system which could be potentially incorporated into semiconductor nanofabrication, this selective removal is predominantly done by a wet etch/activation process. Conversely, this process has numerous disadvantages including lack of control and high generation of waste leading to high cost. For these reasons, our motivation was to move away from the wet etch process and optimise a dry etch which would overcome the limitations associated with the activation process. The work presented herein shows the development of a selective plasma etch process for the removal of P4VP cores from PS-b-P4VP nanopatterned film. Results have shown that a nitrogen reactive ion etch plasma has a selectivity for P4VP of 2.2:1 and suggest that the position of the nitrogen in the aromatic ring of P4VP plays a key role in this selectivity. In situ plasma etching and x-ray photoelectron spectrometry measurements were made without breaking vacuum, confirming that the nitrogen plasma has selectivity for removal of P4VP over PS.

Ion-Exchange-Induced Selective Etching for the Synthesis of Amino-Functionalized Hollow Mesoporous Silica for Elevated-High-Temperature Fuel Cells.

PubMed

Zhang, Jin; Liu, Jian; Lu, Shanfu; Zhu, Haijin; Aili, David; De Marco, Roland; Xiang, Yan; Forsyth, Maria; Li, Qingfeng; Jiang, San Ping

2017-09-20

As differentiated from conventional synthetic processes, amino-functionalized hollow mesoporous silica (NH 2 -HMS) has been synthesized using a new and facile strategy of ion-exchange-induced selective etching of amino-functionalized mesoporous silica (NH 2 -meso-silica) by an alkaline solution. Nuclear magnetic resonance (NMR) spectroscopy and in situ time-resolved small-angle X-ray scattering (SAXS) reveal that ion-exchange-induced selective etching arises from the gradient distribution of OH - in the NH 2 -meso-silica nanospheres. Moreover, the ion-exchange-induced selective etching mechanism is verified through a successful synthesis of hollow mesoporous silica. After infiltration with phosphotungstic acid (PWA), PWA-NH 2 -HMS nanoparticles are dispersed in the poly(ether sulfone)-polyvinylpyrrolidone (PES-PVP) matrix, forming a hybrid PWA-NH 2 -HMS/PES-PVP nanocomposite membrane. The resultant nanocomposite membrane with an optimum loading of 10 wt % of PWA-NH 2 -HMS showed an enhanced proton conductivity of 0.175 S cm -1 and peak power density of 420 mW cm -2 at 180 °C under anhydrous conditions. Excellent durability of the hybrid composite membrane fuel cell has been demonstrated at 200 °C. The results of this study demonstrated the potential of the facile synthetic strategy in the fabrication of NH 2 -HMS with controlled mesoporous structure for application in nanocomposite membranes as a technology platform for elevated-temperature proton exchange membrane fuel cells.

Predictions of ion energy distributions and radical fluxes in radio frequency biased inductively coupled plasma etching reactors

NASA Astrophysics Data System (ADS)

Hoekstra, Robert J.; Kushner, Mark J.

1996-03-01

Inductively coupled plasma (ICP) reactors are being developed for low gas pressure (<10s mTorr) and high plasma density ([e]≳1011 cm-3) microelectronics fabrication. In these reactors, the plasma is generated by the inductively coupled electric field while an additional radio frequency (rf) bias is applied to the substrate. One of the goals of these systems is to independently control the magnitude of the ion flux by the inductively coupled power deposition, and the acceleration of ions into the substrate by the rf bias. In high plasma density reactors the width of the sheath above the wafer may be sufficiently thin that ions are able to traverse it in approximately 1 rf cycle, even at 13.56 MHz. As a consequence, the ion energy distribution (IED) may have a shape typically associated with lower frequency operation in conventional reactive ion etching tools. In this paper, we present results from a computer model for the IED incident on the wafer in ICP etching reactors. We find that in the parameter space of interest, the shape of the IED depends both on the amplitude of the rf bias and on the ICP power. The former quantity determines the average energy of the IED. The latter quantity controls the width of the sheath, the transit time of ions across the sheath and hence the width of the IED. In general, high ICP powers (thinner sheaths) produce wider IEDs.

Molecular dynamics simulations of Si etching in Cl- and Br-based plasmas: Cl{sup +} and Br{sup +} ion incidence in the presence of Cl and Br neutrals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakazaki, Nobuya, E-mail: nakazaki.nobuya.58x@st.kyoto-u.ac.jp; Takao, Yoshinori; Eriguchi, Koji

Classical molecular dynamics (MD) simulations have been performed for Cl{sup +} and Br{sup +} ions incident on Si(100) surfaces with Cl and Br neutrals, respectively, to gain a better understanding of the ion-enhanced surface reaction kinetics during Si etching in Cl- and Br-based plasmas. The ions were incident normally on surfaces with translational energies in the range E{sub i} = 20–500 eV, and low-energy neutrals of E{sub n} = 0.01 eV were also incident normally thereon with the neutral-to-ion flux ratio in the range Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 0–100, where an improved Stillinger--Weber potential form was employed for the interatomic potential concerned. The etch yieldsmore » and thresholds presently simulated were in agreement with the experimental results previously reported for Si etching in Cl{sub 2} and Br{sub 2} plasmas as well as in Cl{sup +}, Cl{sub 2}{sup +}, and Br{sup +} beams, and the product stoichiometry simulated was consistent with that observed during Ar{sup +} beam incidence on Si in Cl{sub 2}. Moreover, the surface coverage of halogen atoms, halogenated layer thickness, surface stoichiometry, and depth profile of surface products simulated for Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 100 were in excellent agreement with the observations depending on E{sub i} reported for Si etching in Cl{sub 2} plasmas. The MD also indicated that the yield, coverage, and surface layer thickness are smaller in Si/Br than in Si/Cl system, while the percentage of higher halogenated species in product and surface stoichiometries is larger in Si/Br. The MD further indicated that in both systems, the translational energy distributions of products and halogen adsorbates desorbed from surfaces are approximated by two Maxwellians of temperature T{sub 1} ≈ 2500 K and T{sub 2} ≈ 7000–40 000 K. These energy distributions are discussed in terms of the desorption or evaporation from hot spots formed through chemically enhanced physical sputtering and physically enhanced chemical sputtering, which have so far been speculated to both occur in the ion-enhanced surface reaction kinetics of plasma etching.« less

Prediction of plasma-induced damage distribution during silicon nitride etching using advanced three-dimensional voxel model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuboi, Nobuyuki, E-mail: Nobuyuki.Kuboi@jp.sony.com; Tatsumi, Tetsuya; Kinoshita, Takashi

2015-11-15

The authors modeled SiN film etching with hydrofluorocarbon (CH{sub x}F{sub y}/Ar/O{sub 2}) plasma considering physical (ion bombardment) and chemical reactions in detail, including the reactivity of radicals (C, F, O, N, and H), the area ratio of Si dangling bonds, the outflux of N and H, the dependence of the H/N ratio on the polymer layer, and generation of by-products (HCN, C{sub 2}N{sub 2}, NH, HF, OH, and CH, in addition to CO, CF{sub 2}, SiF{sub 2}, and SiF{sub 4}) as ion assistance process parameters for the first time. The model was consistent with the measured C-F polymer layer thickness,more » etch rate, and selectivity dependence on process variation for SiN, SiO{sub 2}, and Si film etching. To analyze the three-dimensional (3D) damage distribution affected by the etched profile, the authors developed an advanced 3D voxel model that can predict the time-evolution of the etched profile and damage distribution. The model includes some new concepts for gas transportation in the pattern using a fluid model and the property of voxels called “smart voxels,” which contain details of the history of the etching situation. Using this 3D model, the authors demonstrated metal–oxide–semiconductor field-effect transistor SiN side-wall etching that consisted of the main-etch step with CF{sub 4}/Ar/O{sub 2} plasma and an over-etch step with CH{sub 3}F/Ar/O{sub 2} plasma under the assumption of a realistic process and pattern size. A large amount of Si damage induced by irradiated hydrogen occurred in the source/drain region, a Si recess depth of 5 nm was generated, and the dislocated Si was distributed in a 10 nm deeper region than the Si recess, which was consistent with experimental data for a capacitively coupled plasma. An especially large amount of Si damage was also found at the bottom edge region of the metal–oxide–semiconductor field-effect transistors. Furthermore, our simulation results for bulk fin-type field-effect transistor side-wall etching showed that the Si fin (source/drain region) was directly damaged by high energy hydrogen and had local variations in the damage distribution, which may lead to a shift in the threshold voltage and the off-state leakage current. Therefore, side-wall etching and ion implantation processes must be carefully designed by considering the Si damage distribution to achieve low damage and high transistor performance for complementary metal–oxide–semiconductor devices.« less

SEMICONDUCTOR TECHNOLOGY Texturization of mono-crystalline silicon solar cells in TMAH without the addition of surfactant

NASA Astrophysics Data System (ADS)

Weiying, Ou; Yao, Zhang; Hailing, Li; Lei, Zhao; Chunlan, Zhou; Hongwei, Diao; Min, Liu; Weiming, Lu; Jun, Zhang; Wenjing, Wang

2010-10-01

Etching was performed on (100) silicon wafers using silicon-dissolved tetramethylammonium hydroxide (TMAH) solutions without the addition of surfactant. Experiments were carried out in different TMAH concentrations at different temperatures for different etching times. The surface phenomena, etching rates, surface morphology and surface reflectance were analyzed. Experimental results show that the resulting surface covered with uniform pyramids can be realized with a small change in etching rates during the etching process. The etching mechanism is explained based on the experimental results and the theoretical considerations. It is suggested that all the components in the TMAH solutions play important roles in the etching process. Moreover, TMA+ ions may increase the wettability of the textured surface. A good textured surface can be obtained in conditions where the absorption of OH-/H2O is in equilibrium with that of TMA+/SiO2 (OH)22-.

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 long etching time and will be use during analysis of detectors exposed on the International Space Station during DOSIS and MATROSHKA experiments. The help and support of Yukio Uchihori and Hisashi Kitamura during the irradiations at HIMAC is highly appreciated. This work was supported by the Polish Ministry of Science and Higher Education, grants: No N N505 261535 and No. DWM/N118/ESA/2008.

Porous Two-Dimensional Transition Metal Carbide (MXene) Flakes for High-Performance Li-Ion Storage

DOE PAGES

Ren, Chang E.; Zhao, M-Q; Makaryan, Taron; ...

2016-02-16

Herein we develop a chemical etching method to produce porous two-dimensional (2D) Ti 3C 2T x MXenes at room temperature in aqueous solutions. The as-produced porous Ti 3C 2T x (p-Ti 3C 2T x) have larger specific surface areas and more open structures than their pristine counterparts, and can be fabricated into flexible films with, or without, the addition of carbon nanotubes (CNTs). The as-fabricated p-Ti 3C 2T x/CNT films showed significantly improved lithium ion storage capabilities compared to pristine Ti 3C 2T x based films, with a very high capacity of ≈1250 mAh g -1 at 0.1 C, excellentmore » cycling stability, and good rate performance (330 mAh g -1 at 10 C). Using the same chemical etching method, we also made porous Nb 2CT x and V 2CT x MXenes. Therefore, this study provides a simple, yet effective, procedure to introduce pores into MXenes and possibly other 2D sheets that in turn, can enhance their electrochemical properties.« less

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, several experiments on RIE in BCl3 and Cl2 (and sometimes Ar) had demonstrated the 10:1 selectivity ratio, and further experiments to enhance understanding and obtain further guidance for optimizing process conditions were planned.

O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties.

PubMed

Yang, Cheng; Wang, Ying; Jacobs, Christopher B; Ivanov, Ilia N; Venton, B Jill

2017-05-16

Carbon nanotube (CNT) based microelectrodes exhibit rapid and selective detection of neurotransmitters. While different fabrication strategies and geometries of CNT microelectrodes have been characterized, relatively little research has investigated ways to selectively enhance their electrochemical properties. In this work, we introduce two simple, reproducible, low-cost, and efficient surface modification methods for carbon nanotube yarn microelectrodes (CNTYMEs): O 2 plasma etching and antistatic gun treatment. O 2 plasma etching was performed by a microwave plasma system with oxygen gas flow and the optimized time for treatment was 1 min. The antistatic gun treatment flows ions by the electrode surface; two triggers of the antistatic gun was the optimized number on the CNTYME surface. Current for dopamine at CNTYMEs increased 3-fold after O 2 plasma etching and 4-fold after antistatic gun treatment. When the two treatments were combined, the current increased 12-fold, showing the two effects are due to independent mechanisms that tune the surface properties. O 2 plasma etching increased the sensitivity due to increased surface oxygen content but did not affect surface roughness while the antistatic gun treatment increased surface roughness but not oxygen content. The effect of tissue fouling on CNT yarns was studied for the first time, and the relatively hydrophilic surface after O 2 plasma etching provided better resistance to fouling than unmodified or antistatic gun treated CNTYMEs. Overall, O 2 plasma etching and antistatic gun treatment improve the sensitivity of CNTYMEs by different mechanisms, providing the possibility to tune the CNTYME surface and enhance sensitivity.

Effect of pH on ion current through conical nanopores

NASA Astrophysics Data System (ADS)

Chander, M.; Kumar, R.; Kumar, S.; Kumar, N.

2018-05-01

Here, we examined ionic current behavior of conical nanopores at different pH and a fixed ion concentration of potassium halide (KCl). Conical shaped nanopores have been developed by chemical etching technique in polyethylene terephthalate (PET) membrane/foil of thickness 12 micron. For this we employed a self-assembled electrochemical cell having two chambers and the foil was fitted in the centre of cell. The nanopores were produced in the foil using etching and stopping solutions. The experimental results show that ionic current rectification (ICR) occurs through synthesized conical nanopores. Further, ion current increases significantly with increase of voltage from the base side of nanopores to the tip side at fixed pH of electrolyte.

Study of Thermal Electrical Modified Etching for Glass and Its Application in Structure Etching

PubMed Central

Zhan, Zhan; Li, Wei; Yu, Lingke; Wang, Lingyun; Sun, Daoheng

2017-01-01

In this work, an accelerating etching method for glass named thermal electrical modified etching (TEM etching) is investigated. Based on the identification of the effect in anodic bonding, a novel method for glass structure micromachining is proposed using TEM etching. To validate the method, TEM-etched glasses are prepared and their morphology is tested, revealing the feasibility of the new method for micro/nano structure micromachining. Furthermore, two kinds of edge effect in the TEM and etching processes are analyzed. Additionally, a parameter study of TEM etching involving transferred charge, applied pressure, and etching roughness is conducted to evaluate this method. The study shows that TEM etching is a promising manufacture method for glass with low process temperature, three-dimensional self-control ability, and low equipment requirement. PMID:28772521

Correlation of III/V semiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

NASA Astrophysics Data System (ADS)

Gerhard, FRANZ; Ralf, MEYER; Markus-Christian, AMANN

2017-12-01

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance (ECR) were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine- and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I(V) characteristics obtained using a Langmuir probe, plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I(V) characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I(V) characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar- and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the non-invasive optical method of emission spectroscopy, particularly actinometry, was investigated, and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately +/- 5 % , the etch rate shows a slightly concave shape in contrast to the plasma density.

Neutral beam and ICP etching of HKMG MOS capacitors: Observations and a plasma-induced damage model

NASA Astrophysics Data System (ADS)

Kuo, Tai-Chen; Shih, Tzu-Lang; Su, Yin-Hsien; Lee, Wen-Hsi; Current, Michael Ira; Samukawa, Seiji

2018-04-01

In this study, TiN/HfO2/Si metal-oxide-semiconductor (MOS) capacitors were etched by a neutral beam etching technique under two contrasting conditions. The configurations of neutral beam etching technique were specially designed to demonstrate a "damage-free" condition or to approximate "reactive-ion-etching-like" conditions to verify the effect of plasma-induced damage on electrical characteristics of MOS capacitors. The results show that by neutral beam etching (NBE), the interface state density (Dit) and the oxide trapped charge (Qot) were lower than routine plasma etching. Furthermore, the decrease in capacitor size does not lead to an increase in leakage current density, indicating less plasma induced side-wall damage. We present a plasma-induced gate stack damage model which we demonstrate by using these two different etching configurations. These results show that NBE is effective in preventing plasma-induced damage at the high-k/Si interface and on the high-k oxide sidewall and thus improve the electrical performance of the gate structure.

Local atomic and electronic structure of oxide/GaAs and SiO2/Si interfaces using high-resolution XPS

NASA Technical Reports Server (NTRS)

Grunthaner, F. J.; Grunthaner, P. J.; Vasquez, R. P.; Lewis, B. F.; Maserjian, J.; Madhukar, A.

1979-01-01

The chemical structures of thin SiO2 films, thin native oxides of GaAs (20-30 A), and the respective oxide-semiconductor interfaces, have been investigated using high-resolution X-ray photoelectron spectroscopy. Depth profiles of these structures have been obtained using argon ion bombardment and wet chemical etching techniques. The chemical destruction induced by the ion profiling method is shown by direct comparison of these methods for identical samples. Fourier transform data-reduction methods based on linear prediction with maximum entropy constraints are used to analyze the discrete structure in oxides and substrates. This discrete structure is interpreted by means of a structure-induced charge-transfer model.

Ion beam texturing

NASA Technical Reports Server (NTRS)

Hudson, W. R.

1976-01-01

A microscopic surface texture is created by sputter etching a surface while simultaneously sputter depositing a lower sputter yield material onto the surface. A xenon ion beam source has been used to perform this texturing process on samples as large as three centimeters in diameter. Ion beam textured surface structures have been characterized with SEM photomicrographs for a large number of materials including Cu, Al, Si, Ti, Ni, Fe, Stainless steel, Au, and Ag. Surfaces have been textured using a variety of low sputter yield materials - Ta, Mo, Nb, and Ti. The initial stages of the texture creation have been documented, and the technique of ion beam sputter removal of any remaining deposited material has been studied. A number of other texturing parameters have been studied such as the variation of the texture with ion beam power, surface temperature, and the rate of texture growth with sputter etching time.

ScAlN etch mask for highly selective silicon etching

DOE PAGES

Henry, Michael David; Young, Travis R.; Griffin, Ben

2017-09-08

Here, this work reports the utilization of a recently developed film, ScAlN, as a silicon etch mask offering significant improvements in high etch selectivity to silicon. Utilization of ScAlN as a fluorine chemistry based deep reactive ion etch mask demonstrated etch selectivity at 23 550:1, four times better than AlN, 11 times better than Al 2O 3, and 148 times better than silicon dioxide with significantly less resputtering at high bias voltage than either Al 2O 3 or AlN. Ellipsometry film thickness measurements show less than 0.3 nm/min mask erosion rates for ScAlN. Micromasking of resputtered Al for Al 2Omore » 3, AlN, and ScAlN etch masks is also reported here, utilizing cross-sectional scanning electron microscope and confocal microscope roughness measurements. With lower etch bias, the reduced etch rate can be optimized to achieve a trench bottom surface roughness that is comparable to SiO 2 etch masks. Etch mask selectivity enabled by ScAlN is likely to make significant improvements in microelectromechanical systems, wafer level packaging, and plasma dicing of silicon.« less

A nontransferring dry adhesive with hierarchical polymer nanohairs.

PubMed

Jeong, Hoon Eui; Lee, Jin-Kwan; Kim, Hong Nam; Moon, Sang Heup; Suh, Kahp Y

2009-04-07

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (approximately 26 N/cm(2) in maximum) in the angled direction and easy detachment (approximately 2.2 N/cm(2)) in the opposite direction, with a hysteresis value of approximately 10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 microm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 x 37.5 cm(2), second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization.

A nontransferring dry adhesive with hierarchical polymer nanohairs

PubMed Central

Jeong, Hoon Eui; Lee, Jin-Kwan; Kim, Hong Nam; Moon, Sang Heup; Suh, Kahp Y.

2009-01-01

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (≈26 N/cm2 in maximum) in the angled direction and easy detachment (≈2.2 N/cm2) in the opposite direction, with a hysteresis value of ≈10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 μm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 × 37.5 cm2, second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization. PMID:19304801

Dosimetry measurements using Timepix in mixed radiation fields induced by heavy ions; comparison with standard dosimetry methods

PubMed Central

Ploc, Ondrej; Kubancak, Jan; Sihver, Lembit; Uchihori, Yukio; Jakubek, Jan; Ambrozova, Iva; Molokanov, Alexander; Pinsky, Lawrence

2014-01-01

Objective of our research was to explore capabilities of Timepix for its use as a single dosemeter and LET spectrometer in mixed radiation fields created by heavy ions. We exposed it to radiation field (i) at heavy ion beams at HIMAC, Chiba, Japan, (ii) in the CERN's high-energy reference field (CERF) facility at Geneva, France/Switzerland, (iii) in the exposure room of the proton therapy laboratory at JINR, Dubna, Russia, and (iv) onboard aircraft. We compared the absolute values of dosimetric quantities obtained with Timepix and with other dosemeters and spectrometers like tissue-equivalent proportional counter (TEPC) Hawk, silicon detector Liulin, and track-etched detectors (TEDs).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, Michael David; Young, Travis R.; Griffin, Ben

Here, this work reports the utilization of a recently developed film, ScAlN, as a silicon etch mask offering significant improvements in high etch selectivity to silicon. Utilization of ScAlN as a fluorine chemistry based deep reactive ion etch mask demonstrated etch selectivity at 23 550:1, four times better than AlN, 11 times better than Al 2O 3, and 148 times better than silicon dioxide with significantly less resputtering at high bias voltage than either Al 2O 3 or AlN. Ellipsometry film thickness measurements show less than 0.3 nm/min mask erosion rates for ScAlN. Micromasking of resputtered Al for Al 2Omore » 3, AlN, and ScAlN etch masks is also reported here, utilizing cross-sectional scanning electron microscope and confocal microscope roughness measurements. With lower etch bias, the reduced etch rate can be optimized to achieve a trench bottom surface roughness that is comparable to SiO 2 etch masks. Etch mask selectivity enabled by ScAlN is likely to make significant improvements in microelectromechanical systems, wafer level packaging, and plasma dicing of silicon.« less

Metal catalyst technique for texturing silicon solar cells

DOEpatents

Ruby, Douglas S.; Zaidi, Saleem H.

2001-01-01

Textured silicon solar cells and techniques for their manufacture utilizing metal sources to catalyze formation of randomly distributed surface features such as nanoscale pyramidal and columnar structures. These structures include dimensions smaller than the wavelength of incident light, thereby resulting in a highly effective anti-reflective surface. According to the invention, metal sources present in a reactive ion etching chamber permit impurities (e.g. metal particles) to be introduced into a reactive ion etch plasma resulting in deposition of micro-masks on the surface of a substrate to be etched. Separate embodiments are disclosed including one in which the metal source includes one or more metal-coated substrates strategically positioned relative to the surface to be textured, and another in which the walls of the reaction chamber are pre-conditioned with a thin coating of metal catalyst material.

Optical and electrical properties of ion beam textured Kapton and Teflon

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1977-01-01

An electron bombardment argon ion source was used to ion etch polyimide (Kapton) and fluorinated ethylene, FEP (Teflon). Samples of polyimide and FEP were exposed to (0.5-1.0) keV Ar ions at ion current densities of (1.0-1/8) mA/sq cm for various exposure times. Changes in the optical and electrical properties of the samples were used to characterize the exposure. Spectral reflectance and transmittance measurements were made between 0.33 and 2.16 micron m using an integrating sphere after each exposure. From these measurements, values of solar absorptance were obtained. Total emittance measurements were also recorded for some samples. Surface resistivity was used to determine changes in the electrical conductivity of the etched samples. A scanning electron microscope recorded surface structure after exposure. Spectral optical data, resistivity measurements, calculated absorptance and emittance measurements are presented along with photomicrographs of the surface structure for the various exposures to Ar ions.

Process For Patterning Dispenser-Cathode Surfaces

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Deininger, William D.

1989-01-01

Several microfabrication techniques combined into process cutting slots 100 micrometer long and 1 to 5 micrometer wide into tungsten dispenser cathodes for traveling-wave tubes. Patterned photoresist serves as mask for etching underlying aluminum. Chemically-assisted ion-beam etching with chlorine removes exposed parts of aluminum layer. Etching with fluorine or chlorine trifluoride removes tungsten not masked by aluminum layer. Slots enable more-uniform low-work function coating dispensed to electron-emitting surface. Emission of electrons therefore becomes more uniform over cathode surface.

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

NASA Technical Reports Server (NTRS)

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

Underlying role of mechanical rigidity and topological constraints in physical sputtering and reactive ion etching of amorphous materials

NASA Astrophysics Data System (ADS)

Bhattarai, Gyanendra; Dhungana, Shailesh; Nordell, Bradley J.; Caruso, Anthony N.; Paquette, Michelle M.; Lanford, William A.; King, Sean W.

2018-05-01

Analytical expressions describing ion-induced sputter or etch processes generally relate the sputter yield to the surface atomic binding energy (Usb) for the target material. While straightforward to measure for the crystalline elemental solids, Usb is more complicated to establish for amorphous and multielement materials due to composition-driven variations and incongruent sublimation. In this regard, we show that for amorphous multielement materials, the ion-driven yield can instead be better understood via a consideration of mechanical rigidity and network topology. We first demonstrate a direct relationship between Usb, bulk modulus, and ion sputter yield for the elements, and then subsequently prove our hypothesis for amorphous multielement compounds by demonstrating that the same relationships exist between the reactive ion etch (RIE) rate and nanoindentation Young's modulus for a series of a -Si Nx :H and a -Si OxCy :H thin films. The impact of network topology is further revealed via application of the Phillips-Thorpe theory of topological constraints, which directly relates the Young's modulus to the mean atomic coordination () for an amorphous solid. The combined analysis allows the trends and plateaus in the RIE rate to be ultimately reinterpreted in terms of the atomic structure of the target material through a consideration of . These findings establish the important underlying role of mechanical rigidity and network topology in ion-solid interactions and provide additional considerations for the design and optimization of radiation-hard materials in nuclear and outer space environments.

Ion beam figuring of CVD silicon carbide mirrors

NASA Astrophysics Data System (ADS)

Gailly, P.; Collette, J.-P.; Fleury Frenette, K.; Jamar, C.

2017-11-01

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in reason of its good behavior under polishing. The advantage of applying ion beam figuring (IBF) to CVD-SiC over other surface figure-improving techniques is discussed herein. The results of an IBF sequence performed at the Centre Spatial de Liège on a 100 mm CVD-SiC mirror are reported. The process allowed to reduce the mirror surface errors from 243 nm to 13 nm rms . Beside the surface figure, roughness is another critical feature to consider in order to preserve the optical quality of CVD-SiC . Thus, experiments focusing on the evolution of roughness were performed in various ion beam etching conditions. The roughness of samples etched at different depths down to 3 ≠m was determined with an optical profilometer. These measurements emphasize the importance of selecting the right combination of gas and beam energy to keep roughness at a low level. Kaufman-type ion sources are generally used to perform IBF but the performance of an end-Hall ion source in figuring CVD-SiC mirrors was also evaluated in this study. In order to do so, ion beam etching profiles obtained with the end-Hall source on CVD-SiC were measured and used as a basis for IBF simulations.

Synthesis and characterization of graphene quantum dots and their size reduction using swift heavy ion beam

NASA Astrophysics Data System (ADS)

Mishra, Praveen; Bhat, Badekai Ramchandra

2018-04-01

Graphene quantum dots (GQDs) are nanosized fragments of graphene displaying quantum confinement effect. They have shown to be prepared from various methods which include ion beam etching of graphene. However, recently the modification of the GQDs has garnered tremendous attention owing to its suitability for various applications. Here, we have studied the effect of swift ion beam irradiation on the properties of GQDs. The ion beam treatment on the GQDs exhibited the change in observed photoluminescence of GQDs as they exhibited a blue luminescence on excitation with longwave UV (≈365 nm) due to the reduction in size and removal of the ethoxy (-C-O-C-) groups present on the quantum dots. This was confirmed by transmission electron microscopy, particle size analysis, and Fourier transform infrared spectroscopy.

Investigation of MeV-Cu implantation and channeling effects into porous silicon formation

NASA Astrophysics Data System (ADS)

Ahmad, M.; Naddaf, M.

2011-11-01

P-type (1 1 1) silicon wafers were implanted by copper ions (2.5 MeV) in channeling and random directions using ion beam accelerator of the Atomic Energy Commission of Syria (AECS). The effect of implantation direction on formation process of porous silicon (PS) using electrochemical etching method has been investigated using scanning electron microscope (SEM) and photoluminescence (PL) techniques. SEM observations revealed that the size, shape and density of the formed pores are highly affected by the direction of beam implantation. This in turn is seen to influence the PL behavior of the PS.

Electron collisions with atoms, ions, molecules, and surfaces: Fundamental science empowering advances in technology

PubMed Central

Bartschat, Klaus; Kushner, Mark J.

2016-01-01

Electron collisions with atoms, ions, molecules, and surfaces are critically important to the understanding and modeling of low-temperature plasmas (LTPs), and so in the development of technologies based on LTPs. Recent progress in obtaining experimental benchmark data and the development of highly sophisticated computational methods is highlighted. With the cesium-based diode-pumped alkali laser and remote plasma etching of Si3N4 as examples, we demonstrate how accurate and comprehensive datasets for electron collisions enable complex modeling of plasma-using technologies that empower our high-technology–based society. PMID:27317740

Selective dry etching of III-V nitrides in Cl{sub 2}/Ar, CH{sub 4}/H{sub 2}/Ar, ICi/Ar, and IBr/Ar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vartuli, C.B.; Pearton, S.J.; MacKenzie, J.D.

1996-10-01

The selectivity for etching the binary (GaN, AlN, and InN) and ternary nitrides (InGaN and InAlN) relative to each other in Cl{sub 2}/Ar, CH{sub 4}/H{sub 2}/Ar, ICl/Ar, or IBr/Ar electron cyclotron resonance (ECR) plasmas, and Cl{sub 2}/Ar or CH{sub 4}/H{sub 2}/Ar reactive ion (RIE) plasmas was investigated. Cl-based etches appear to be the best choice for maximizing the selectivity of GaN over the other nitrides. GaN/AlN and GaN/InGaN etch rate ratios of {approximately} 10 were achieved at low RF power in Cl{sub 2}/Ar under ECR and RIE conditions, respectively. GaN/InN selectivity of 10 was found in ICl under ECR conditions.more » A relatively high selectivity (> 6) of InN/GaN was achieved in CH{sub 4}/H{sub 2}/Ar under ECR conditions at low RF powers (50 W). Since the high bond strengths of the nitrides require either high ion energies or densities to achieve practical etch rates it is difficult to achieve high selectivities.« less

A plasmaless, photochemical etch process for porous organosilicate glass films

NASA Astrophysics Data System (ADS)

Ryan, E. Todd; Molis, Steven E.

2017-12-01

A plasmaless, photochemical etch process using ultraviolet (UV) light in the presence of NH3 or O2 etched porous organosilicate glass films, also called pSiCOH films, in a two-step process. First, a UV/NH3 or UV/O2 treatment removed carbon (mostly methyl groups bonded to silicon) from a pSiCOH film by demethylation to a depth determined by the treatment exposure time. Second, aqueous HF was used to selectively remove the demethylated layer of the pSiCOH film leaving the methylated layer below. UV in the presence of inert gas or H2 did not demethylate the pSiCOH film. The depth of UV/NH3 demethylation followed diffusion limited kinetics and possible mechanisms of demethylation are presented. Unlike reactive plasma processes, which contain ions that can damage surrounding structures during nanofabrication, the photochemical etch contains no damaging ions. Feasibility of the photochemical etching was shown by comparing it to a plasma-based process to remove the pSiCOH dielectric from between Cu interconnect lines, which is a critical step during air gap fabrication. The findings also expand our understanding of UV photon interactions in pSiCOH films that may contribute to plasma-induced damage to pSiCOH films.

Partially etched Ti3AlC2 as a promising high capacity Lithium-ion battery anode.

PubMed

Chen, Xifan; Zhu, Yuanzhi; Zhu, Xiaoquan; Peng, Wenchao; Li, Yang; Zhang, Guoliang; Zhang, Fengbao; Fan, Xiaobin

2018-06-25

MXenes, a family of two-dimensional transition-metal carbide and nitride materials, are supposed to be the promising materials in energy storage because of the high electronic conductivity, hydrophilic surfaces and low diffusion barriers. MXenes are generally prepared by removing the "A" elements (A = Al, Si, Sn, etc.) from their corresponding MAX phases by using hydrofluoric acid (HF) and the other etching agents, despite the fact that these "A" elements usually have great volumetric and gravimetric capacities. Herein, we studied the etching progress of Ti3AlC2 and evaluated their anode performance in Lithium-ion batteries. We found that a partially etched sample (0.5h-peTi3C2Tx) showed much higher capacity (160 mA h g-1, 331.6 mA h cm-3 at 1C) when compared with the fully etched Ti3C2Tx (110 mA h g-1, 190.3 mA h cm-3 at 1C). Besides, a 99% capacity retention was observed even after 1000 cycles in the 0.5h-peTi3C2Tx anode. This interesting result can be explained, at least in part, by the alloying of the residue Al element during lithiation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A role for ion implantation in quantum computing

NASA Astrophysics Data System (ADS)

Jamieson, David N.; Prawer, Steven; Andrienko, Igor; Brett, David A.; Millar, Victoria

2001-04-01

We propose to create arrays of phosphorus atoms in silicon for quantum computing using ion implantation. Since the implantation of the ions is essentially random, the yield of usefully spaced atoms is low and therefore some method of registering the passage of a single ion is required. This can be accomplished by implantation of the ions through a thin surface layer consisting of resist. Changes to the chemical and/or electrical properties of the resist will be used to mark the site of the buried ion. For chemical changes, the latent damage will be developed and the atomic force microscope (AFM) used to image the changes in topography. Alternatively, changes in electrical properties (which obviate the need for post-irradiation chemical etching) will be used to register the passage of the ion using scanning tunneling microscopy (STM), the surface current imaging mode of the AFM. We address the central issue of the contrast created by the passage of a single ion through resist layers of PMMA and C 60.

Growth of biaxially textured template layers using ion beam assisted deposition

NASA Astrophysics Data System (ADS)

Park, Seh-Jin

A two-step IBAD (ion beam assisted deposition) method is investigated, and compared to the conventional IBAD methods. The two step method uses surface energy anisotropy to achieve uniaxial texture and ion beam irradiation for biaxial texture. The biaxial texture was achieved by selective surface etching and enhanced by grain overgrowth. In this method, biaxial texture alignment is performed on a (001) uniaxially textured buffer layer. The material selected for achieving uniaxial texture, YBCO (YBa2Cu3O7-x), has strong surface energy anisotropy. YBCO is chemically susceptible to the reaction with the adjacent layer. Yttria stabilized zirconia (YSZ) was used to prevent the reaction between YBCO and the substrates (polycrystalline Ni alloy [Hastelloy] and amorphous SiNx/Si). A SrTiO3 layer was deposited on the uniaxially textured YBCO layer to retard stoichiometry change with subsequent processing. STO is well lattice matched with YBCO. A top layer of Ni was then deposited. The Ni layer was used for studying the effect of grain overgrowth. The obtained uniaxial Ni films were used for subsequent ion beam processing. Ar ion beam irradiation onto the uniaxially textured Ni film was used to study the effect of selective grain etching in achieving in-plane aligned Ni grains. Additional Ni deposition induces the overgrowth of the in-plane aligned Ni grains and, finally, the overall in-plane alignment. The in-plane alignment is examined with XRD phi scan. The effect of surface polarity of insulating oxide substrates on the epitaxial growth behavior was investigated. The lattice strain energy was the most important factor for determining the orientation of Ni films on a non-polar surface. However, for a polar surface, the surface energy plays an important role in determining the final orientation of the Ni films based on the experimental and theoretical results. Y2O3 growth behavior was also studied. The lattice strain energy is the most important factor for Y2O3 growth on single crystalline substrates. The surface energy anisotropy is the most important factor for the growth on amorphous substrates. The XRD phi scan study shows that Ar ion beam irradiation with favorable angle of incidence enhances the in-plane alignment of Y2O3 films grown on randomly oriented substrates due to the ion channeling.

A selective iodide ion sensor electrode based on functionalized ZnO nanotubes.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-02-04

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10-6 to 1 × 10-1 M) and excellent sensitivity of -62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10-7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples.

A Selective Iodide Ion Sensor Electrode Based on Functionalized ZnO Nanotubes

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-01-01

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10−6 to 1 × 10−1 M) and excellent sensitivity of −62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10−7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples. PMID:23385412

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

NASA Astrophysics Data System (ADS)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Surface microroughness of ion-beam etched optical surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savvides, N.

2005-03-01

Ion-beam etching (IBE) and ion-beam figuring techniques using low-energy ion-beam sources have been applied for more than ten years in the fabrication and finishing of extremely smooth high-performance optics. We used optical interferometric techniques and atomic force microscopy to study the evolution of the surface root-mean-square (rms) microroughness, Rq, as a function of depth of a material removed (0-3000 nm) by a broad ion-beam source (Ar{sup +} ions of energy 600 eV and ion current density of 1 mA cm{sup -2}). Highly polished samples of fused silica and Zerodur (Rq{approx}3.5 A) showed a small decrease in microroughness (to 2.5 A)more » after 3000-nm IBE removal while an ultrapolished single-crystal sapphire sample (Rq{approx}1 A rms) retained its very low microroughness during IBE. Power spectral density functions over the spatial frequency interval of measurement (f=5x10{sup -3}-25 {mu}m{sup -1}) indicate that the IBE surfaces have minimal subsurface damage and low optical scatter.« less

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.

Method of forming aperture plate for electron microscope

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1974-01-01

An electron microscope is described with an electron source a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen. It also has objective lens with an annular objective aperture, for focusing electrons passing through the specimen onto an image plane. A method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques is included.

Tracking of Polycarbonate Films using Low-energy Ions Final Report CRADA No. TC-774-94

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musket, R. G.

2018-01-24

Ion tracking is performed almost exclusively using ions with energies near or above the maximum in electronic stopping. For the present study, we have examined the results of etching ion tracks created by ions bombarding polycarbonate films with energies corresponding to stopping well below the maximum and just above the anticipated threshold for creating etchable latent tracks. Low-energy neon and argon ions with 18-60 keV /amu and fluences of about 10 8/cm 2 were used to examine the limits for producing etchable tracks in polycarbonate films. By concentrating on the early stages of etching (i.e., -20 nm < SEM holemore » diameter < -100 nm), we can directly relate the energy deposition calculated for the incident ion to the creation of etchable tracks. The experimental results will be discussed with regard to the energy losses of the ions in the polycarbonate films and to the formation of continuous latent tracks through the entire thickness the films. These results have significant implications with respect to the threshold for formation of etchable tracks and to the use of low-energy ions for lithographic applications.« less

Deep reactive ion etching of 4H-SiC via cyclic SF6/O2 segments

NASA Astrophysics Data System (ADS)

Luna, Lunet E.; Tadjer, Marko J.; Anderson, Travis J.; Imhoff, Eugene A.; Hobart, Karl D.; Kub, Fritz J.

2017-10-01

Cycles of inductively coupled SF6/O2 plasma with low (9%) and high (90%) oxygen content etch segments are used to produce up to 46.6 µm-deep trenches with 5.5 µm-wide openings in single-crystalline 4H-SiC substrates. The low oxygen content segment serves to etch deep in SiC whereas the high oxygen content segment serves to etch SiC at a slower rate, targeting carbon-rich residues on the surface as the combination of carbon-rich and fluorinated residues impact sidewall profile. The cycles work in concert to etch past 30 µm at an etch rate of ~0.26 µm min-1 near room temperature, while maintaining close to vertical sidewalls, high aspect ratio, and high mask selectivity. In addition, power ramps during the low oxygen content segment is used to produce a 1:1 ratio of mask opening to trench bottom width. The effect of process parameters such as cycle time and backside substrate cooling on etch depth and micromasking of the electroplated nickel etch mask are investigated.

Tandem-Mirror Ion Source

NASA Technical Reports Server (NTRS)

Biddle, A.; Stone, N.; Reasoner, D.; Chisholm, W.; Reynolds, J.

1986-01-01

Improved ion source produces beam of ions at any kinetic energy from 1 to 1,000 eV, with little spread in energy or angle. Such ion beams useful in studies of surface properties of materials, surface etching, deposition, and development of plasma-diagnostic instrumentation. Tandemmirror ion source uses electrostatic and magnetic fields to keep electrons in ionization chamber and assure uniform output ion beam having low divergence in energy and angle.

Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices

PubMed Central

Yong, Keong; Ashraf, Ali; Kang, Pilgyu; Nam, SungWoo

2016-01-01

We report a one-step polymer-free approach to patterning graphene using a stencil mask and oxygen plasma reactive-ion etching, with a subsequent polymer-free direct transfer for flexible graphene devices. Our stencil mask is fabricated via a subtractive, laser cutting manufacturing technique, followed by lamination of stencil mask onto graphene grown on Cu foil for patterning. Subsequently, micro-sized graphene features of various shapes are patterned via reactive-ion etching. The integrity of our graphene after patterning is confirmed by Raman spectroscopy. We further demonstrate the rapid prototyping capability of a stretchable, crumpled graphene strain sensor and patterned graphene condensation channels for potential applications in sensing and heat transfer, respectively. We further demonstrate that the polymer-free approach for both patterning and transfer to flexible substrates allows the realization of cleaner graphene features as confirmed by water contact angle measurements. We believe that our new method promotes rapid, facile fabrication of cleaner graphene devices, and can be extended to other two dimensional materials in the future. PMID:27118249

Defect formation during chlorine-based dry etching and their effects on the electronic and structural properties of InP/InAsP quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landesman, Jean-Pierre, E-mail: jean-pierre.landesman@univ-rennes1.fr; Jiménez, Juan; Torres, Alfredo

The general objective is the investigation of the defects formed by dry etching tools such as those involved in the fabrication of photonic devices with III–V semiconductors. Emphasis is put on plasma exposures with chlorine-based chemistries. In addition to identifying these defects and describing their effects on the electro-optic and structural properties, the long-term target would be to predict the impact on the parameters of importance for photonic devices, and possibly include these predictions in their design. The work is first centered on explaining the experimental methodology. This methodology starts with the design and growth of a quantum well structuremore » on indium phosphide, including ternary indium arsenide/phosphide quantum wells with graded arsenic/phosphor composition. These samples have then been characterized by luminescence methods (photo- and cathodoluminescence), high-resolution transmission electron microscopy, and secondary ion mass spectrometry. As one of the parameters of importance in this study, the authors have also included the doping level. The samples have been exposed to the etching plasmas for “short” durations that do not remove completely the quantum wells, but change their optical signature. No masking layer with lithographic features was involved as this work is purely oriented to study the interaction between the plasma and the samples. A significant difference in the luminescence spectra of the as-grown undoped and doped samples is observed. A mechanism describing the effect of the built-in electric field appearing as a consequence of the doping profile is proposed. This mechanism involves quantum confined Stark effect and electric-field induced carrier escape from the quantum wells. In the following part, the effects of exposure to various chlorine-based plasmas were explored. Differences are again observed between the undoped and doped samples, especially for chemistries containing silicon tetrachloride. Secondary ion mass spectrometry indicates penetration of chlorine in the structures. Transmission electron microscopy is used to characterize the quantum well structure before and after plasma bombardment. By examining carefully the luminescence spectral properties, the authors could demonstrate the influence of the etching plasmas on the built-in electric field (in the case of doped samples), and relate it to some ionic species penetrating the structures. Etching plasmas involving both chlorine and nitrogen have also been studied. The etching rate for these chemistries is much slower than for some of the silicon tetrachloride based chemistries. Their effects on the samples are also very different, showing much reduced effect on the built-in electric field (for the doped samples), but significant blue-shifts of the luminescence peaks that the authors attributed to the penetration of nitrogen in the structures. Nitrogen, in interstitial locations, induces mechanical compressive stress that accounts for the blue-shifts. Finally, from the comparison between secondary ion mass spectrometry and luminescence spectra, the authors suggest some elements for a general mechanism involved in the etching by chloride-chemistries, in which a competition takes place between the species at the surface, active for the etching mechanism, and the species that penetrate the structure, lost for the etching process, but relevant in terms of impact on the electro-optic and structural features of the exposed materials.« less

Patterned microstructures formed with MeV Au implantation in Si(1 0 0)

NASA Astrophysics Data System (ADS)

Rout, Bibhudutta; Greco, Richard R.; Zachry, Daniel P.; Dymnikov, Alexander D.; Glass, Gary A.

2006-09-01

Energetic (MeV) Au implantation in Si(1 0 0) (n-type) through masked micropatterns has been used to create layers resistant to KOH wet etching. Microscale patterns were produced in PMMA and SU(8) resist coatings on the silicon substrates using P-beam writing and developed. The silicon substrates were subsequently exposed using 1.5 MeV Au 3+ ions with fluences as high as 1 × 10 16 ions/cm 2 and additional patterns were exposed using copper scanning electron microscope calibration grids as masks on the silicon substrates. When wet etched with KOH microstructures were created in the silicon due to the resistance to KOH etching cause by the Au implantation. The process of combining the fabrication of masked patterns with P-beam writing with broad beam Au implantation through the masks can be a promising, cost-effective process for nanostructure engineering with Si.

Wafer scale oblique angle plasma etching

DOEpatents

Burckel, David Bruce; Jarecki, Jr., Robert L.; Finnegan, Patrick Sean

2017-05-23

Wafer scale oblique angle etching of a semiconductor substrate is performed in a conventional plasma etch chamber by using a fixture that supports a multiple number of separate Faraday cages. Each cage is formed to include an angled grid surface and is positioned such that it will be positioned over a separate one of the die locations on the wafer surface when the fixture is placed over the wafer. The presence of the Faraday cages influences the local electric field surrounding each wafer die, re-shaping the local field to be disposed in alignment with the angled grid surface. The re-shaped plasma causes the reactive ions to follow a linear trajectory through the plasma sheath and angled grid surface, ultimately impinging the wafer surface at an angle. The selected geometry of the Faraday cage angled grid surface thus determines the angle at with the reactive ions will impinge the wafer.

Bottom-up and top-down fabrication of nanowire-based electronic devices: In situ doping of vapor liquid solid grown silicon nanowires and etch-dependent leakage current in InGaAs tunnel junctions

NASA Astrophysics Data System (ADS)

Kuo, Meng-Wei

Semiconductor nanowires are important components in future nanoelectronic and optoelectronic device applications. These nanowires can be fabricated using either bottom-up or top-down methods. While bottom-up techniques can achieve higher aspect ratio at reduced dimension without having surface and sub-surface damage, uniform doping distributions with abrupt junction profiles are less challenging for top-down methods. In this dissertation, nanowires fabricated by both methods were systematically investigated to understand: (1) the in situ incorporation of boron (B) dopants in Si nanowires grown by the bottom-up vapor-liquid-solid (VLS) technique, and (2) the impact of plasma-induced etch damage on InGaAs p +-i-n+ nanowire junctions for tunnel field-effect transistors (TFETs) applications. In Chapter 2 and 3, the in situ incorporation of B in Si nanowires grown using silane (SiH4) or silicon tetrachloride (SiCl4) as the Si precursor and trimethylboron (TMB) as the p-type dopant source is investigated by I-V measurements of individual nanowires. The results from measurements using a global-back-gated test structure reveal nonuniform B doping profiles on nanowires grown from SiH4, which is due to simultaneous incorporation of B from nanowire surface and the catalyst during VLS growth. In contrast, a uniform B doping profile in both the axial and radial directions is achieved for TMBdoped Si nanowires grown using SiCl4 at high substrate temperatures. In Chapter 4, the I-V characteristics of wet- and dry-etched InGaAs p+-i-n+ junctions with different mesa geometries, orientations, and perimeter-to-area ratios are compared to evaluate the impact of the dry etch process on the junction leakage current properties. Different post-dry etch treatments, including wet etching and thermal annealing, are performed and the effectiveness of each is assessed by temperaturedependent I-V measurements. As compared to wet-etched control devices, dry-etched junctions have a significantly higher leakage current and a current kink in the reverse bias regime, which is likely due to additional trap states created by plasma-induced damage during the Cl2/Ar/H2 mesa isolation step. These states extend more than 60 nm from the mesa surface and can only be partially passivated after a thermal anneal at 350°C for 20 minutes. The evolution of the electrical properties with post-dry etch treatments indicates that the shallow and deep-level trap states resulting from ion-induced point defects, arsenic vacancies and hydrogen-dopant complexes are the primary cause of degradation in the electrical properties of the dry-etched junctions.

Electrochemical planarization

DOEpatents

Bernhardt, A.F.; Contolini, R.J.

1993-10-26

In a process for fabricating planarized thin film metal interconnects for integrated circuit structures, a planarized metal layer is etched back to the underlying dielectric layer by electropolishing, ion milling or other procedure. Electropolishing reduces processing time from hours to minutes and allows batch processing of multiple wafers. The etched back planarized thin film interconnect is flush with the dielectric layer. 12 figures.

Highly Manufacturable Deep (Sub-Millimeter) Etching Enabled High Aspect Ratio Complex Geometry Lego-Like Silicon Electronics.

PubMed

Ghoneim, Mohamed Tarek; Hussain, Muhammad Mustafa

2017-04-01

A highly manufacturable deep reactive ion etching based process involving a hybrid soft/hard mask process technology shows high aspect ratio complex geometry Lego-like silicon electronics formation enabling free-form (physically flexible, stretchable, and reconfigurable) electronic systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoscale Reactive Ion Etching of Silicon Nitride Thin Films for Embedded Nanomagnetic Device Fabrication

NASA Astrophysics Data System (ADS)

Hibbard-Lubow, David Luke

The demands of digital memory have increased exponentially in recent history, requiring faster, smaller and more accurate storage methods. Two promising solutions to this ever-present problem are Bit Patterned Media (BPM) and Spin-Transfer Torque Magnetic Random Access Memory (STT-MRAM). Producing these technologies requires difficult and expensive fabrication techniques. Thus, the production processes must be optimized to allow these storage methods to compete commercially while continuing to increase their information storage density and reliability. I developed a process for the production of nanomagnetic devices (which can take the form of several types of digital memory) embedded in thin silicon nitride films. My focus was on optimizing the reactive ion etching recipe required to embed the device in the film. Ultimately, I found that recipe 37 (Power: 250W, CF4 nominal/actual flow rate: 25/25.4 sccm, O2 nominal/actual flow rate: 3.1/5.2 sccm, which gave a maximum pressure around 400 mTorr) gave the most repeatable and anisotropic results. I successfully used processes described in this thesis to make embedded nanomagnets, which could be used as bit patterned media. Another promising application of this work is to make embedded magnetic tunneling junctions, which are the storage medium used in MRAM. Doing so will require still some tweaks to the fabrication methods. Techniques for making these changes and their potential effects are discussed.

Pattern transfer with stabilized nanoparticle etch masks

NASA Astrophysics Data System (ADS)

Hogg, Charles R.; Picard, Yoosuf N.; Narasimhan, Amrit; Bain, James A.; Majetich, Sara A.

2013-03-01

Self-assembled nanoparticle monolayer arrays are used as an etch mask for pattern transfer into Si and SiOx substrates. Crack formation within the array is prevented by electron beam curing to fix the nanoparticles to the substrate, followed by a brief oxygen plasma to remove excess carbon. This leaves a dot array of nanoparticle cores with a minimum gap of 2 nm. Deposition and liftoff can transform the dot array mask into an antidot mask, where the gap is determined by the nanoparticle core diameter. Reactive ion etching is used to transfer the dot and antidot patterns into the substrate. The effect of the gap size on the etching rate is modeled and compared with the experimental results.

Nanostructuring of conduction channels in (In,Ga)As-InP heterostructures: Overcoming carrier generation caused by Ar ion milling

NASA Astrophysics Data System (ADS)

Hortelano, V.; Weidlich, H.; Semtsiv, M. P.; Masselink, W. T.; Ramsteiner, M.; Jahn, U.; Biermann, K.; Takagaki, Y.

2018-04-01

Nanometer-sized channels are fabricated in (In,Ga)As-InP heterostructures using Ar ion milling. The ion milling causes spontaneous creation of nanowires, and moreover, electrical conduction of the surface as carriers is generated by sputtering-induced defects. We demonstrate a method to restore electrical isolation in the etched area that is compatible with the presence of the nanochannels. We remove the heavily damaged surface layer using a diluted HCl solution and subsequently recover the crystalline order in the moderately damaged part by annealing. We optimize the HCl concentration to make the removal stop on its own before reaching the conduction channel part. The lateral depletion in the channels is shown to be almost absent.

Development of new FIB technology for EUVL mask repair

NASA Astrophysics Data System (ADS)

Aramaki, Fumio; Ogawa, Takashi; Matsuda, Osamu; Kozakai, Tomokazu; Sugiyama, Yasuhiko; Oba, Hiroshi; Yasaka, Anto; Amano, Tsuyoshi; Shigemura, Hiroyuki; Suga, Osamu

2011-04-01

The next generation EUVL masks beyond hp15nm are difficult to repair for the current repair technologies including focused ion beam (FIB) and electron beam (EB) in view of the minimum repairable size. We developed a new FIB technology to repair EUVL masks. Conventional FIB use gallium ions (Ga+) generated by a liquid metal ion source (LMIS), but the new FIB uses hydrogen ions (H2+) generated by a gas field ion source (GFIS). The minimum reaction area of H2+ FIB is theoretically much smaller than that of EB. We investigated the repair performance of H2+ FIB. In the concrete, we evaluated image resolution, scan damage, etching rate, material selectivity of etching and actinic image of repaired area. The most important result is that there was no difference between the repaired area and the non-repaired one on actinic images. That result suggests that the H2+ GFIS technology is a promising candidate for the solution to repair the next generation EUVL masks beyond hp15nm.

A simple method used to evaluate phase-change materials based on focused-ion beam technique

NASA Astrophysics Data System (ADS)

Peng, Cheng; Wu, Liangcai; Rao, Feng; Song, Zhitang; Lv, Shilong; Zhou, Xilin; Du, Xiaofeng; Cheng, Yan; Yang, Pingxiong; Chu, Junhao

2013-05-01

A nanoscale phase-change line cell based on focused-ion beam (FIB) technique has been proposed to evaluate the electrical property of the phase-change material. Thanks to the FIB-deposited SiO2 hardmask, only one etching step has been used during the fabrication process of the cell. Reversible phase-change behaviors are observed in the line cells based on Al-Sb-Te and Ge-Sb-Te films. The low power consumption of the Al-Sb-Te based cell has been explained by theoretical calculation accompanying with thermal simulation. This line cell is considered to be a simple and reliable method in evaluating the application prospect of a certain phase-change material.

Compact Submillimeter-Wave Receivers Made with Semiconductor Nano-Fabrication Technologies

NASA Technical Reports Server (NTRS)

Jung, C.; Thomas, B.; Lee, C.; Peralta, A.; Chattopadhyay, G.; Gill, J.; Cooper, K.; Mehdi, I.

2011-01-01

Advanced semiconductor nanofabrication techniques are utilized to design, fabricate and demonstrate a super-compact, low-mass (<10 grams) submillimeter-wave heterodyne front-end. RF elements such as waveguides and channels are fabricated in a silicon wafer substrate using deep-reactive ion etching (DRIE). Etched patterns with sidewalls angles controlled with 1 deg precision are reported, while maintaining a surface roughness of better than 20 nm rms for the etched structures. This approach is being developed to build compact 2-D imaging arrays in the THz frequency range.

A high-performance nanoporous Si/Al2O3 foam lithium-ion battery anode fabricated by selective chemical etching of the Al-Si alloy and subsequent thermal oxidation.

PubMed

Hwang, Gaeun; Park, Hyungmin; Bok, Taesoo; Choi, Sinho; Lee, Sungjun; Hwang, Inchan; Choi, Nam-Soon; Seo, Kwanyong; Park, Soojin

2015-03-14

Nanostructured micrometer-sized Al-Si particles are synthesized via a facile selective etching process of Al-Si alloy powder. Subsequent thin Al2O3 layers are introduced on the Si foam surface via a selective thermal wet oxidation process of etched Al-Si particles. The resulting Si/Al2O3 foam anodes exhibit outstanding cycling stability (a capacity retention of 78% after 300 cycles at the C/5 rate) and excellent rate capability.

Black silicon: fabrication methods, properties and solar energy applications

DOE PAGES

Liu, Xiaogang; Coxon, Paul R.; Peters, Marius; ...

2014-08-04

Black silicon (BSi) represents a very active research area in renewable energy materials. The rise of BSi as a focus of study for its fundamental properties and potentially lucrative practical applications is shown by several recent results ranging from solar cells and light-emitting devices to antibacterial coatings and gas-sensors. Here in this article, the common BSi fabrication techniques are first reviewed, including electrochemical HF etching, stain etching, metal-assisted chemical etching, reactive ion etching, laser irradiation and the molten salt Fray-Farthing-Chen-Cambridge (FFC-Cambridge) process. The utilization of BSi as an anti-reflection coating in solar cells is then critically examined and appraised, basedmore » upon strategies towards higher efficiency renewable solar energy modules. Methods of incorporating BSi in advanced solar cell architectures and the production of ultra-thin and flexible BSi wafers are also surveyed. Particular attention is given to routes leading to passivated BSi surfaces, which are essential for improving the electrical properties of any devices incorporating BSi, with a special focus on atomic layer deposition of Al 2O 3. Finally, three potential research directions worth exploring for practical solar cell applications are highlighted, namely, encapsulation effects, the development of micro-nano dual-scale BSi, and the incorporation of BSi into thin solar cells. It is intended that this paper will serve as a useful introduction to this novel material and its properties, and provide a general overview of recent progress in research currently being undertaken for renewable energy applications.« less

Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

NASA Astrophysics Data System (ADS)

Sohrabi, M.; Habibi, M.; Ramezani, V.

2017-02-01

The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of 4.4 × 104 tracks/cm2 was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

Exploration of suitable dry etch technologies for directed self-assembly

NASA Astrophysics Data System (ADS)

Yamashita, Fumiko; Nishimura, Eiichi; Yatsuda, Koichi; Mochiki, Hiromasa; Bannister, Julie

2012-03-01

Directed self-assembly (DSA) has shown the potential to replace traditional resist patterns and provide a lower cost alternative for sub-20-nm patterns. One of the possible roadblocks for DSA implementation is the ability to etch the polymers to produce quality masks for subsequent etch processes. We have studied the effects of RF frequency and etch chemistry for dry developing DSA patterns. The results of the study showed a capacitively-coupled plasma (CCP) reactor with very high frequency (VHF) had superior pattern development after the block co-polymer (BCP) etch. The VHF CCP demonstrated minimal BCP height loss and line edge roughness (LER)/line width roughness (LWR). The advantage of CCP over ICP is the low dissociation so the etch rate of BCP is maintained low enough for process control. Additionally, the advantage of VHF is the low electron energy with a tight ion energy distribution that enables removal of the polymethyl methacrylate (PMMA) with good selectivity to polystyrene (PS) and minimal LER/LWR. Etch chemistries were evaluated on the VHF CCP to determine ability to treat the BCPs to increase etch resistance and feature resolution. The right combination of RF source frequencies and etch chemistry can help overcome the challenges of using DSA patterns to create good etch results.

Ion-Deposited Polished Coatings

NASA Technical Reports Server (NTRS)

Banks, B. A.

1986-01-01

Polished, dense, adherent coatings relatively free of imperfections. New process consists of using broad-beam ion source in evacuated chamber to ion-clean rotating surface that allows grazing incidence of ion beam. This sputter cleans off absorbed gases, organic contaminants, and oxides of mirror surface. In addition to cleaning, surface protrusions sputter-etched away. Process particularly adaptable to polishing of various substrates for optical or esthetic purposes.

Nanogrids and Beehive-Like Nanostructures Formed by Plasma Etching the Self-Organized SiGe Islands

NASA Astrophysics Data System (ADS)

Chang, Yuan-Ming; Jian, Sheng-Rui; Juang, Jenh-Yih

2010-09-01

A lithography-free method for fabricating the nanogrids and quasi-beehive nanostructures on Si substrates is developed. It combines sequential treatments of thermal annealing with reactive ion etching (RIE) on SiGe thin films grown on (100)-Si substrates. The SiGe thin films deposited by ultrahigh vacuum chemical vapor deposition form self-assembled nanoislands via the strain-induced surface roughening (Asaro-Tiller-Grinfeld instability) during thermal annealing, which, in turn, serve as patterned sacrifice regions for subsequent RIE process carried out for fabricating nanogrids and beehive-like nanostructures on Si substrates. The scanning electron microscopy and atomic force microscopy observations confirmed that the resultant pattern of the obtained structures can be manipulated by tuning the treatment conditions, suggesting an interesting alternative route of producing self-organized nanostructures.

Micromirror arrays to assess luminescent nano-objects.

PubMed

Kawakami, Yoichi; Kanai, Akinobu; Kaneta, Akio; Funato, Mitsuru; Kikuchi, Akihiko; Kishino, Katsumi

2011-05-01

We propose an array of submicrometer mirrors to assess luminescent nano-objects. Micromirror arrays (MMAs) are fabricated on Si (001) wafers via selectively doping Ga using the focused ion beam technique to form p-type etch stop regions, subsequent anisotropic chemical etching, and Al deposition. MMAs provide two benefits: reflection of luminescence from nano-objects within MMAs toward the Si (001) surface normal and nano-object labeling. The former increases the probability of optics collecting luminescence and is demonstrated by simulations based on the ray-tracing and finite-difference time-domain methods as well as by experiments. The latter enables different measurements to be repeatedly performed on a single nano-object located at a certain micromirror. For example, a single InGaN∕GaN nanocolumn is assessed by scanning electron microscopy and microphotoluminescence spectroscopy.

Gold surface plasmon crystal structure based-on polystyrene template for biosensor application.

PubMed

Cheng, Min-Zhuo; Zhang, Jing; Bao, Dequan; Huang, Xiwei

2018-05-21

In this communication, we assembled ordered polystyrene (PS) microsphere array as a template with the drop-coating method, and the oxygen plasma was used to etch the template to adjust the spacing between the PS microspheres. Nano-triangular gold array and silver nano-pyramid array were obtained by ion beam sputtering to deposit precious metal gold and silver. We observed the surface morphology of Au and Au/Ag composite films by scanning electron microscope and characterized the films by X-ray diffraction and ultraviolet/visible light spectrophotometer. The results show that the etching time of oxygen plasma has an obvious effect in adjusting the spacing between PSs and has a significant effect on the morphology of Au structure. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication Methods for Adaptive Deformable Mirrors

NASA Technical Reports Server (NTRS)

Toda, Risaku; White, Victor E.; Manohara, Harish; Patterson, Keith D.; Yamamoto, Namiko; Gdoutos, Eleftherios; Steeves, John B.; Daraio, Chiara; Pellegrino, Sergio

2013-01-01

Previously, it was difficult to fabricate deformable mirrors made by piezoelectric actuators. This is because numerous actuators need to be precisely assembled to control the surface shape of the mirror. Two approaches have been developed. Both approaches begin by depositing a stack of piezoelectric films and electrodes over a silicon wafer substrate. In the first approach, the silicon wafer is removed initially by plasmabased reactive ion etching (RIE), and non-plasma dry etching with xenon difluoride (XeF2). In the second approach, the actuator film stack is immersed in a liquid such as deionized water. The adhesion between the actuator film stack and the substrate is relatively weak. Simply by seeping liquid between the film and the substrate, the actuator film stack is gently released from the substrate. The deformable mirror contains multiple piezoelectric membrane layers as well as multiple electrode layers (some are patterned and some are unpatterned). At the piezolectric layer, polyvinylidene fluoride (PVDF), or its co-polymer, poly(vinylidene fluoride trifluoroethylene P(VDF-TrFE) is used. The surface of the mirror is coated with a reflective coating. The actuator film stack is fabricated on silicon, or silicon on insulator (SOI) substrate, by repeatedly spin-coating the PVDF or P(VDFTrFE) solution and patterned metal (electrode) deposition. In the first approach, the actuator film stack is prepared on SOI substrate. Then, the thick silicon (typically 500-micron thick and called handle silicon) of the SOI wafer is etched by a deep reactive ion etching process tool (SF6-based plasma etching). This deep RIE stops at the middle SiO2 layer. The middle SiO2 layer is etched by either HF-based wet etching or dry plasma etch. The thin silicon layer (generally called a device layer) of SOI is removed by XeF2 dry etch. This XeF2 etch is very gentle and extremely selective, so the released mirror membrane is not damaged. It is possible to replace SOI with silicon substrate, but this will require tighter DRIE process control as well as generally longer and less efficient XeF2 etch. In the second approach, the actuator film stack is first constructed on a silicon wafer. It helps to use a polyimide intermediate layer such as Kapton because the adhesion between the polyimide and silicon is generally weak. A mirror mount ring is attached by using adhesive. Then, the assembly is partially submerged in liquid water. The water tends to seep between the actuator film stack and silicon substrate. As a result, the actuator membrane can be gently released from the silicon substrate. The actuator membrane is very flat because it is fixed to the mirror mount prior to the release. Deformable mirrors require extremely good surface optical quality. In the technology described here, the deformable mirror is fabricated on pristine substrates such as prime-grade silicon wafers. The deformable mirror is released by selectively removing the substrate. Therefore, the released deformable mirror surface replicates the optical quality of the underlying pristine substrate.

New 3D structuring process for non-integrated circuit related technologies (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nouri, Lamia; Possémé, Nicolas; Landis, Stéfan; Milesi, Frédéric; Gaillard, Frédéric-Xavier

2017-04-01

Fabrication processes that microelectronic developed for Integrated circuit (IC) technologies for decades, do not meet the new emerging structuration's requirements, in particular non-IC related technologies one, such as MEMS/NEMS, Micro-Fluidics, photovoltaics, lenses. Actually complex 3D structuration requires complex lithography patterning approaches such as gray-scale electron beam lithography, laser ablation, focused ion beam lithography, two photon polymerization. It is now challenging to find cheaper and easiest technique to achieve 3D structures. In this work, we propose a straightforward process to realize 3D structuration, intended for silicon based materials (Si, SiN, SiOCH). This structuration technique is based on nano-imprint lithography (NIL), ion implantation and selective wet etching. In a first step a pattern is performed by lithography on a substrate, then ion implantation is realized through a resist mask in order to create localized modifications in the material, thus the pattern is transferred into the subjacent layer. Finally, after the resist stripping, a selective wet etching is carried out to remove selectively the modified material regarding the non-modified one. In this paper, we will first present results achieved with simple 2D line array pattern processed either on Silicon or SiOCH samples. This step have been carried out to demonstrate the feasibility of this new structuration process. SEM pictures reveals that "infinite" selectivity between the implanted areas versus the non-implanted one could be achieved. We will show that a key combination between the type of implanted ion species and wet etching chemistries is required to obtain such results. The mechanisms understanding involved during both implantation and wet etching processes will also be presented through fine characterizations with Photoluminescence, Raman and Secondary Ion Mass Spectrometry (SIMS) for silicon samples, and ellipso-porosimetry and Fourier Transform InfraRed spectroscopy (FTIR) for SiOCH samples. Finally the benefit of this new patterning approach will be presented on 3D patterns structures.

Dry etching of copper phthalocyanine thin films: effects on morphology and surface stoichiometry.

PubMed

Van Dijken, Jaron G; Brett, Michael J

2012-08-24

We investigate the evolution of copper phthalocyanine thin films as they are etched with argon plasma. Significant morphological changes occur as a result of the ion bombardment; a planar surface quickly becomes an array of nanopillars which are less than 20 nm in diameter. The changes in morphology are independent of plasma power, which controls the etch rate only. Analysis by X-ray photoelectron spectroscopy shows that surface concentrations of copper and oxygen increase with etch time, while carbon and nitrogen are depleted. Despite these changes in surface stoichiometry, we observe no effect on the work function. The absorbance and X-ray diffraction spectra show no changes other than the peaks diminishing with etch time. These findings have important implications for organic photovoltaic devices which seek nanopillar thin films of metal phthalocyanine materials as an optimal structure.

Design and grayscale fabrication of beamfanners in a silicon substrate

NASA Astrophysics Data System (ADS)

Ellis, Arthur Cecil

2001-11-01

This dissertation addresses important first steps in the development of a grayscale fabrication process for multiple phase diffractive optical elements (DOS's) in silicon. Specifically, this process was developed through the design, fabrication, and testing of 1-2 and 1-4 beamfanner arrays for 5-micron illumination. The 1-2 beamfanner arrays serve as a test-of- concept and basic developmental step toward the construction of the 1-4 beamfanners. The beamfanners are 50 microns wide, and have features with dimensions of between 2 and 10 microns. The Iterative Annular Spectrum Approach (IASA) method, developed by Steve Mellin of UAH, and the Boundary Element Method (BEM) are the design and testing tools used to create the beamfanner profiles and predict their performance. Fabrication of the beamfanners required the techniques of grayscale photolithography and reactive ion etching (RIE). A 2-3micron feature size 1-4 silicon beamfanner array was fabricated, but the small features and contact photolithographic techniques available prevented its construction to specifications. A second and more successful attempt was made in which both 1-4 and 1-2 beamfanner arrays were fabricated with a 5-micron minimum feature size. Photolithography for the UAH array was contracted to MEMS-Optical of Huntsville, Alabama. A repeatability study was performed, using statistical techniques, of 14 photoresist arrays and the subsequent RIE process used to etch the arrays in silicon. The variance in selectivity between the 14 processes was far greater than the variance between the individual etched features within each process. Specifically, the ratio of the variance of the selectivities averaged over each of the 14 etch processes to the variance of individual feature selectivities within the processes yielded a significance level below 0.1% by F-test, indicating that good etch-to-etch process repeatability was not attained. One of the 14 arrays had feature etch-depths close enough to design specifications for optical testing, but 5- micron IR illumination of the 1-4 and 1-2 beamfanners yielded no convincing results of beam splitting in the detector plane 340 microns from the surface of the beamfanner array.

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.

Tuning the thickness of exfoliated quasi-two-dimensional β-Ga2O3 flakes by plasma etching

NASA Astrophysics Data System (ADS)

Kwon, Yongbeom; Lee, Geonyeop; Oh, Sooyeoun; Kim, Jihyun; Pearton, Stephen J.; Ren, Fan

2017-03-01

We demonstrated the thinning of exfoliated quasi-two-dimensional β-Ga2O3 flakes by using a reactive ion etching technique. Mechanical exfoliation of the bulk β-Ga2O3 by using an adhesive tape was followed by plasma etching to tune its thickness. Since β-Ga2O3 is not a van der Waals material, it is challenging to obtain ultra-thin flakes below a thickness of 100 nm. In this study, an etch rate of approximately 16 nm/min was achieved at a power of 200 W with a flow of 50 sccm of SF6, and under these conditions, thinning of β-Ga2O3 flakes from 300 nm down to ˜60 nm was achieved with smooth morphology. We believe that the reaction between SF6 and Ga2O3 results in oxygen and volatile oxygen fluoride compounds, and non-volatile compounds such as GaFX that can be removed by ion bombardment. The opto-electrical properties were also characterized by fabricating solar-blind photodetectors using the plasma-thinned β-Ga2O3 flakes; these detectors showed fast response and decay with excellent responsivity and selectivity. Our results pave the way for tuning the thickness of two-dimensional materials by using this scalable, industry-compatible dry etching technique.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogdanova, M. A.; Zyryanov, S. M.; Faculty of Physics, Moscow State University, MSU, Moscow

Energy distribution and the flux of the ions coming on a surface are considered as the key-parameters in anisotropic plasma etching. Since direct ion energy distribution (IED) measurements at the treated surface during plasma processing are often hardly possible, there is an opportunity for virtual ones. This work is devoted to the possibility of such indirect IED and ion flux measurements at an rf-biased electrode in low-pressure rf plasma by using a “virtual IED sensor” which represents “in-situ” IED calculations on the absolute scale in accordance with a plasma sheath model containing a set of measurable external parameters. The “virtualmore » IED sensor” should also involve some external calibration procedure. Applicability and accuracy of the “virtual IED sensor” are validated for a dual-frequency reactive ion etching (RIE) inductively coupled plasma (ICP) reactor with a capacitively coupled rf-biased electrode. The validation is carried out for heavy (Ar) and light (H{sub 2}) gases under different discharge conditions (different ICP powers, rf-bias frequencies, and voltages). An EQP mass-spectrometer and an rf-compensated Langmuir probe (LP) are used to characterize plasma, while an rf-compensated retarded field energy analyzer (RFEA) is applied to measure IED and ion flux at the rf-biased electrode. Besides, the pulsed selfbias method is used as an external calibration procedure for ion flux estimating at the rf-biased electrode. It is shown that pulsed selfbias method allows calibrating the IED absolute scale quite accurately. It is also shown that the “virtual IED sensor” based on the simplest collisionless sheath model allows reproducing well enough the experimental IEDs at the pressures when the sheath thickness s is less than the ion mean free path λ{sub i} (s < λ{sub i}). At higher pressure (when s > λ{sub i}), the difference between calculated and experimental IEDs due to ion collisions in the sheath is observed in the low energy range. The effect of electron impact ionization in the sheath on the origin and intensity of low-energy peaks in IED is discussed compared to ion charge-exchange collisions. Obviously, the extrapolation of the “virtual IED sensor” approach to higher pressures requires developing some other sheath models, taking into account both ion and electron collisions and probably including even a model of the whole plasma volume instead of plasma sheath one.« less

Wavelength-scale Microlasers based on VCSEL-Photonic Crystal Architecture

DTIC Science & Technology

2015-01-20

molecular beam epitaxy , MBE). We will also assume the triangular lattice of air...Abbreviations, and Acronyms InP: indium phosphide InGaAsP: indium gallium arsenide phosphide MBE: molecular beam epiitaxy VCSEL : vertical cavity...substrates and were grown by MBE. Electron beam lithography and reactive ion etching was used to deep‐etch the holes of the PhC‐ VCSELS ,

DOE Office of Scientific and Technical Information (OSTI.GOV)

Surodin, S. I., E-mail: surodin.bsn@mail.ru; Nikolitchev, D. E.; Kryukov, R. N.

The concentration profiles of species in silicon subjected to gallium and nitrogen co-implantation and subsequent annealing have been investigated by the method of X-ray photoelectron spectroscopy combined with the layer-by-layer ion etching of the implanted layer. It is shown that practically entire implanted gallium undergoes out-diffusion, but the preliminary implantation of nitrogen for the synthesis of a barrier SiN{sub x} layer makes it possible to avoid the essential loss of gallium. In this case, about 14 % of implanted gallium bond to nitrogen. The obtained data are discussed from the viewpoint of the possibility of ion synthesis of GaN inclusionsmore » in silicon matrix.« less

Nanosilicon dot arrays with a bit pitch and a track pitch of 25 nm formed by electron-beam drawing and reactive ion etching for 1 Tbit/in.{sup 2} storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosaka, Sumio; Sano, Hirotaka; Shirai, Masumi

2006-11-27

The formation of very fine Si dots with a bit pitch and a track pitch of less than 25 nm using electron-beam (EB) lithography on ZEP520 and calixarene EB resists and CF{sub 4} reactive ion etching has been demonstrated. The experimental results indicate that the calixarene resist is very suitable for forming an ultrahigh-packed bit array pattern of Si dots. This result promises to open the way toward 1 Tbit/in.{sup 2} storage using patterned media with a dot size of <15 nm.

Conformal SiO2 coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

PubMed Central

Sobel, Nicolas; Lukas, Manuela; Spende, Anne; Stühn, Bernd; Trautmann, Christina

2015-01-01

Summary Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO2 by atomic layer deposition (ALD). The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS) reveals a homogeneous, conformal layer of SiO2 in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS) confirms the stoichiometric composition of the SiO2 films. Detailed XPS analysis reveals that the mechanism of SiO2 formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced. PMID:25821688

FIB Plan View Preparation and Electron Tomography of Ga-Containing Droplets Induced by Melt-Back Etching in Si.

PubMed

Gries, Katharina I; Werner, Katharina; Beyer, Andreas; Stolz, Wolfgang; Volz, Kerstin

2016-02-01

Melt-back etching is an effect that can occur for gallium (Ga) containing III/V semiconductors grown on Si. Since this effect influences interfaces between the two compounds and therefore the physical characteristics of the material composition, it is desirable to understand its driving forces. Therefore, we investigated Ga grown on Si (001) via metal organic chemical vapor deposition using trimethyl Ga as a precursor. As a result of the melt-back etching, Ga-containing droplets formed on the Si surface which reach into the Si wafer. The shape of these structures was analyzed by plan view investigation and cross sectional tomography in a (scanning) transmission electron microscope. For plan view preparation a focused ion beam was used to avoid damage to the Ga-containing structures, which are sensitive to the chemicals normally used during conventional plan view preparation. Combining the results of both investigation methods confirms that the Ga-containing structure within the Si exhibits a pyramid shape with facets along the Si {111} lattice planes.

Silicon Alignment Pins: An Easy Way to Realize a Wafer-to-Wafer Alignment

NASA Technical Reports Server (NTRS)

Jung-Kubiak, Cecile; Reck, Theodore J.; Lin, Robert H.; Peralta, Alejandro; Gill, John J.; Lee, Choonsup; Siles, Jose; Toda, Risaku; Chattopadhyay, Goutam; Cooper, Ken B.;

Approach to high quality GaN lateral nanowires and planar cavities fabricated by focused ion beam and metal-organic vapor phase epitaxy.

PubMed

Pozina, Galia; Gubaydullin, Azat R; Mitrofanov, Maxim I; Kaliteevski, Mikhail A; Levitskii, Iaroslav V; Voznyuk, Gleb V; Tatarinov, Evgeniy E; Evtikhiev, Vadim P; Rodin, Sergey N; Kaliteevskiy, Vasily N; Chechurin, Leonid S

2018-05-08

We have developed a method to fabricate GaN planar nanowires and cavities by combination of Focused Ion Beam (FIB) patterning of the substrate followed by Metal Organic Vapor Phase Epitaxy (MOVPE). The method includes depositing a silicon nitride mask on a sapphire substrate, etching of the trenches in the mask by FIB with a diameter of 40 nm with subsequent MOVPE growth of GaN within trenches. It was observed that the growth rate of GaN is substantially increased due to enhanced bulk diffusion of the growth precursor therefore the model for analysis of the growth rate was developed. The GaN strips fabricated by this method demonstrate effective luminescence properties. The structures demonstrate enhancement of spontaneous emission via formation of Fabry-Perot modes.

Qualitative modeling of silica plasma etching using neural network

NASA Astrophysics Data System (ADS)

Kim, Byungwhan; Kwon, Kwang Ho

2003-01-01

An etching of silica thin film is qualitatively modeled by using a neural network. The process was characterized by a 23 full factorial experiment plus one center point, in which the experimental factors and ranges include 100-800 W radio-frequency source power, 100-400 W bias power and gas flow rate ratio CHF3/CF4. The gas flow rate ratio varied from 0.2 to 5.0. The backpropagation neural network (BPNN) was trained on nine experiments and tested on six experiments, not pertaining to the original training data. The prediction ability of the BPNN was optimized as a function of the training parameters. Prediction errors are 180 Å/min and 1.33, for the etch rate and anisotropy models, respectively. Physical etch mechanisms were estimated from the three-dimensional plots generated from the optimized models. Predicted response surfaces were consistent with experimentally measured etch data. The dc bias was correlated to the etch responses to evaluate its contribution. Both the source power (plasma density) and bias power (ion directionality) strongly affected the etch rate. The source power was the most influential factor for the etch rate. A conflicting effect between the source and bias powers was noticed with respect to the anisotropy. The dc bias played an important role in understanding or separating physical etch mechanisms.

Fabrication and analysis of single-crystal KTiOPO₄ films with thicknesses in the micrometer range.

PubMed

Ma, Changdong; Lu, Fei; Xu, Bo; Fan, Ranran

2016-02-01

Single-crystal potassium titanyl phosphate (KTiOPO4, KTP) films with thicknesses less than 5 μm are obtained by using helium (He) implantation combined with ion-beam-enhanced etching. A heavily damaged layer created by a 4×10(16)  cm(-2) fluence of 2 MeV He implantation is removed by means of wet chemical etching in hydrofluoric acid (HF). Thus, free-standing films of KTP with thicknesses in the range of 3-5 μm are obtained. The etching rate can be adjusted over a wide range by choosing temperature and HF concentration, as well as annealing conditions. Sharp etching edges and the smooth surface of the film indicate that a high selective-etching rate is achieved in the damaged layer, and the remaining part of the crystal is undamaged. X-ray and Raman-scattering results prove that KTP films have good single-crystal properties.

Quantitative Analysis of Etching Rate Profiles for 11B+-Implanted Si3N4 Film

NASA Astrophysics Data System (ADS)

Nakata, Jyoji; Kajiyama, Kenji

1983-01-01

Etching rate enhancement for 11B+-implanted Si3N4 film was investigated both experimentally and theoretically. The etching solution was concentrated H3PO4 at ˜165°C Film thicknesses were precisely measured by ellipsometry. Enhancement resulted from Si-N bond breaking. This was confirmed by a decrease of infrared absorption at a 12.0 μm wavelength for Si-N bond vibration. Main and additional peaks were observed in the etching rate profile. The former was due to nuclear damage and was well represented by the calculated etching rate profile deduced from the nuclear deposited energy density distribution. The latter existed in the surface region only when the ion projected range was shorter than the film thickness. This peak was possibly caused by charge accumulation in the insulating Si3N4 film during 11B+ implantation.

Chemical method for producing smooth surfaces on silicon wafers

DOEpatents

Yu, Conrad

2003-01-01

An improved method for producing optically smooth surfaces in silicon wafers during wet chemical etching involves a pre-treatment rinse of the wafers before etching and a post-etching rinse. The pre-treatment with an organic solvent provides a well-wetted surface that ensures uniform mass transfer during etching, which results in optically smooth surfaces. The post-etching treatment with an acetic acid solution stops the etching instantly, preventing any uneven etching that leads to surface roughness. This method can be used to etch silicon surfaces to a depth of 200 .mu.m or more, while the finished surfaces have a surface roughness of only 15-50 .ANG. (RMS).

Wafer-scale development and experimental verification of 0.36 mm2 228 mV open-circuit-voltage solid-state CMOS-compatible glucose fuel cell

NASA Astrophysics Data System (ADS)

Arata, Shigeki; Hayashi, Kenya; Nishio, Yuya; Kobayashi, Atsuki; Nakazato, Kazuo; Niitsu, Kiichi

2018-04-01

The world’s smallest (0.36 mm2) solid-state CMOS-compatible glucose fuel cell, which exhibits an open-circuit voltage (OCV) of 228 mV and a power generation density of 1.32 µW/cm2 with a 30 mM glucose solution, is reported in this paper. Compared with conventional wet etching, dry etching (reactive ion etching) for patterning minimizes damage to the anode and cathode, resulting in a cell with a small size and a high OCV, sufficient for CMOS circuit operation.

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

NASA Astrophysics Data System (ADS)

Chen, Zhuojie; She, Didi; Chen, Qinghua; Li, Yanmei; Wu, Wengang

2018-02-01

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

Release of MEMS devices with hard-baked polyimide sacrificial layer

NASA Astrophysics Data System (ADS)

Boroumand Azad, Javaneh; Rezadad, Imen; Nath, Janardan; Smith, Evan; Peale, Robert E.

2013-03-01

Removal of polyimides used as sacrificial layer in fabricating MEMS devices can be challenging after hardbaking, which may easily result by the end of multiple-step processing. We consider the specific commercial co-developable polyimide ProLift 100 (Brewer Science). Excessive heat hardens this material, so that during wet release in TMAH based solvents, intact sheets break free from the substrate, move around in the solution, and break delicate structures. On the other hand, dry reactive-ion etching of hard-baked ProLift is so slow, that MEMS structures are damaged from undesirably-prolonged physical bombardment by plasma ions. We found that blanket exposure to ultraviolet light allows rapid dry etch of the ProLift surrounding the desired structures without damaging them. Subsequent removal of ProLift from under the devices can then be safely performed using wet or dry etch. We demonstrate the approach on PECVD-grown silicon-oxide cantilevers of 100 micron × 100 micron area supported 2 microns above the substrate by ~100-micron-long 8-micron-wide oxide arms.

Porous carbon-free SnSb anodes for high-performance Na-ion batteries

NASA Astrophysics Data System (ADS)

Choi, Jeong-Hee; Ha, Choong-Wan; Choi, Hae-Young; Seong, Jae-Wook; Park, Cheol-Min; Lee, Sang-Min

2018-05-01

A simple melt-spinning/chemical-etching process is developed to create porous carbon-free SnSb anodes. Sodium ion batteries (SIBs) incorporating these anodes exhibit excellent electrochemical performances by accomodating large volume changes during repeated cycling. The porous carbon-free SnSb anode produced by the melt-spinning/chemical-etching process shows a high reversible capacity of 481 mAh g-1, high ICE of 80%, stable cyclability with a high capacity retention of 99% after 100 cycles, and a fast rate capability of 327 mAh g-1 at 4C-rate. Ex-situ X-ray diffraction and high resolution-transmission electron microscopy analyses demonstrate that the synthesized porous carbon-free SnSb anodes involve the highly reversible reaction with sodium through the conversion and recombination reactions during sodiation/desodiation process. The novel and simple melt-spinning/chemical-etching synthetic process represents a technological breakthrough in the commercialization of Na alloy-able anodes for SIBs.

Study on Platinum Coating Depth in Focused Ion Beam Diamond Cutting Tool Milling and Methods for Removing Platinum Layer.

PubMed

Choi, Woong Kirl; Baek, Seung Yub

2015-09-22

In recent years, nanomachining has attracted increasing attention in advanced manufacturing science and technologies as a value-added processes to control material structures, components, devices, and nanoscale systems. To make sub-micro patterns on these products, micro/nanoscale single-crystal diamond cutting tools are essential. Popular non-contact methods for the macro/micro processing of diamond composites are pulsed laser ablation (PLA) and electric discharge machining (EDM). However, for manufacturing nanoscale diamond tools, these machining methods are not appropriate. Despite diamond's extreme physical properties, diamond can be micro/nano machined relatively easily using a focused ion beam (FIB) technique. In the FIB milling process, the surface properties of the diamond cutting tool is affected by the amorphous damage layer caused by the FIB gallium ion collision and implantation and these influence the diamond cutting tool edge sharpness and increase the processing procedures. To protect the diamond substrate, a protection layer-platinum (Pt) coating is essential in diamond FIB milling. In this study, the depth of Pt coating layer which could decrease process-induced damage during FIB fabrication is investigated, along with methods for removing the Pt coating layer on diamond tools. The optimum Pt coating depth has been confirmed, which is very important for maintaining cutting tool edge sharpness and decreasing processing procedures. The ultra-precision grinding method and etching with aqua regia method have been investigated for removing the Pt coating layer. Experimental results show that when the diamond cutting tool width is bigger than 500 nm, ultra-precision grinding method is appropriate for removing Pt coating layer on diamond tool. However, the ultra-precision grinding method is not recommended for removing the Pt coating layer when the cutting tool width is smaller than 500 nm, because the possibility that the diamond cutting tool is damaged by the grinding process will be increased. Despite the etching method requiring more procedures to remove the Pt coating layer after FIB milling, it is a feasible method for diamond tools with under 500 nm width.

Continuous-flow mass production of silicon nanowires via substrate-enhanced metal-catalyzed electroless etching of silicon with dissolved oxygen as an oxidant.

PubMed

Hu, Ya; Peng, Kui-Qing; Liu, Lin; Qiao, Zhen; Huang, Xing; Wu, Xiao-Ling; Meng, Xiang-Min; Lee, Shuit-Tong

2014-01-13

Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods.

Predictive Modeling in Plasma Reactor and Process Design

NASA Technical Reports Server (NTRS)

Hash, D. B.; Bose, D.; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

1997-01-01

Research continues toward the improvement and increased understanding of high-density plasma tools. Such reactor systems are lauded for their independent control of ion flux and energy enabling high etch rates with low ion damage and for their improved ion velocity anisotropy resulting from thin collisionless sheaths and low neutral pressures. Still, with the transition to 300 mm processing, achieving etch uniformity and high etch rates concurrently may be a formidable task for such large diameter wafers for which computational modeling can play an important role in successful reactor and process design. The inductively coupled plasma (ICP) reactor is the focus of the present investigation. The present work attempts to understand the fundamental physical phenomena of such systems through computational modeling. Simulations will be presented using both computational fluid dynamics (CFD) techniques and the direct simulation Monte Carlo (DSMC) method for argon and chlorine discharges. ICP reactors generally operate at pressures on the order of 1 to 10 mTorr. At such low pressures, rarefaction can be significant to the degree that the constitutive relations used in typical CFD techniques become invalid and a particle simulation must be employed. This work will assess the extent to which CFD can be applied and evaluate the degree to which accuracy is lost in prediction of the phenomenon of interest; i.e., etch rate. If the CFD approach is found reasonably accurate and bench-marked with DSMC and experimental results, it has the potential to serve as a design tool due to the rapid time relative to DSMC. The continuum CFD simulation solves the governing equations for plasma flow using a finite difference technique with an implicit Gauss-Seidel Line Relaxation method for time marching toward a converged solution. The equation set consists of mass conservation for each species, separate energy equations for the electrons and heavy species, and momentum equations for the gas. The sheath is modeled by imposing the Bohm velocity to the ions near the walls. The DSMC method simulates each constituent of the gas as a separate species which would be analogous in CFD to employing separate species mass, momentum, and energy equations. All particles including electrons are moved and allowed to collide with one another with the stipulation that the electrons remain tied to the ions consistent with the concept of ambipolar diffusion. The velocities of the electrons are allowed to be modified during collisions and are not confined to a Maxwellian distribution. These benefits come at a price in terms of computational time and memory. The DSMC and CFD are made as consistent as possible by using similar chemistry and power deposition models. Although the comparison of CFD and DSMC is interesting, the main goal of this work is the increased understanding of high-density plasma flowfields that can then direct improvements in both techniques. This work is unique in the level of the physical models employed in both the DSMC and CFD for high-density plasma reactor applications. For example, the electrons are simulated in the present DSMC work which has not been done before for low temperature plasma processing problems. In the CFD approach, for the first time, the charged particle transport (discharge physics) has been self-consistently coupled to the gas flow and heat transfer.

Real-time plasma control in a dual-frequency, confined plasma etcher

NASA Astrophysics Data System (ADS)

Milosavljević, V.; Ellingboe, A. R.; Gaman, C.; Ringwood, J. V.

2008-04-01

The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2 flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor signals onto the control inputs, allowing compensation of the interaction between control paths. The compensated sensor signals and compensated set-points are then used as inputs to proportional-integral-derivative controllers to adjust radio frequency power and oxygen flow to yield the desired ion flux and chemical density. To illustrate the methodology, model-based real-time control is realized in a commercial semiconductor dielectric etch chamber. The two radio frequency symmetric diode operates with typical commercial fluorocarbon feed-gas mixtures (Ar/O2/C4F8). Key parameters for dielectric etching are known to include ion flux to the surface and surface flux of oxygen containing species. Control is demonstrated using diagnostics of electrode-surface ion current, and chemical densities of O, O2, and CO measured by optical emission spectrometry and/or mass spectrometry. Using our model-based real-time control, the set-point tracking accuracy to changes in chemical species density and ion flux is enhanced.

Separating semiconductor devices from substrate by etching graded composition release layer disposed between semiconductor devices and substrate including forming protuberances that reduce stiction

DOEpatents

Tauke-Pedretti, Anna; Nielson, Gregory N; Cederberg, Jeffrey G; Cruz-Campa, Jose Luis

2015-05-12

A method includes etching a release layer that is coupled between a plurality of semiconductor devices and a substrate with an etch. The etching includes etching the release layer between the semiconductor devices and the substrate until the semiconductor devices are at least substantially released from the substrate. The etching also includes etching a protuberance in the release layer between each of the semiconductor devices and the substrate. The etch is stopped while the protuberances remain between each of the semiconductor devices and the substrate. The method also includes separating the semiconductor devices from the substrate. Other methods and apparatus are also disclosed.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching

NASA Astrophysics Data System (ADS)

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-01

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching.

PubMed

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-19

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

Application of 252Cf plasma desorption mass spectrometry in dental research

NASA Astrophysics Data System (ADS)

Fritsch, Hans-Walter; Schmidt, Lothar; Köhl, Peter; Jungclas, Hartmut; Duschner, Heins

1993-07-01

Topically applied fluorides introduced in dental hygiene products elevate the concentration levels of fluoride in oral fluids and thus also affect chemical reactions of enamel de- and remineralisation. The chemical reactions on the surface of tooth enamel still are a subject of controversy. Here 252Cf-plasma desorption mass spectrometry and argon ion etching are used to analyse the molecular structure of the upper layes of enamel. The mass spectrum of untreated enamel is characterised by a series of cluster ions containing phosphate. It is evident that under certain conditions the molecular structure of the surface enamel is completely transformed by treatment with fluorides. The result of the degradation and precipitation processes is reflected by a total replacement of the phosphate by fluoride in the measured cluster ion distribution. Stepwise etching of the upper layers by Ar+ ions reveals the transition from a nearly pure CaF2 structure to the unchanged composition of the enamel mineral.

The Development of III-V Semiconductor MOSFETs for Future CMOS Applications

NASA Astrophysics Data System (ADS)

Greene, Andrew M.

Alternative channel materials with superior transport properties over conventional strained silicon are required for supply voltage scaling in low power complementary metal-oxide-semiconductor (CMOS) integrated circuits. Group III-V compound semiconductor systems offer a potential solution due to their high carrier mobility, low carrier effective mass and large injection velocity. The enhancement in transistor drive current at a lower overdrive voltage allows for the scaling of supply voltage while maintaining high switching performance. This thesis focuses on overcoming several material and processing challenges associated with III-V semiconductor development including a low thermal processing budget, high interface trap state density (Dit), low resistance source/drain contacts and growth on lattice mismatched substrates. Non-planar In0.53Ga0.47As FinFETs were developed using both "gate-first" and "gate-last" fabrication methods for n-channel MOSFETs. Electron beam lithography and anisotropic plasma etching processes were optimized to create highly scaled fins with near vertical sidewalls. Plasma damage was removed using a wet etch process and improvements in gate efficiency were characterized on MOS capacitor structures. A two-step, selective removal of the pre-grown n+ contact layer was developed for "gate-last" recess etching. The final In0.53Ga 0.47As FinFET devices demonstrated an ION = 70 mA/mm, I ON/IOFF ratio = 15,700 and sub-threshold swing = 210 mV/dec. Bulk GaSb and strained In0.36Ga0.64Sb quantum well (QW) heterostructures were developed for p-channel MOSFETs. Dit was reduced to 2 - 3 x 1012 cm-2eV-1 using an InAs surface layer, (NH4)2S passivation and atomic layer deposition (ALD) of Al2O3. A self-aligned "gate-first" In0.36Ga0.64Sb MOSFET fabrication process was invented using a "T-shaped" electron beam resist patterning stack and intermetallic source/drain contacts. Ni contacts annealed at 300°C demonstrated an ION = 166 mA/mm, ION/IOFF ratio = 1,500 and sub-threshold swing = 340 mV/dec. Split C-V measurements were used to extract an effective channel mobility of muh* = 300 cm2/Vs at Ns = 2 x 1012 cm -2. "Gate-last" MOSFETs grown with an epitaxial p + contact layer were fabricated using selective gate-recess etching techniques. A parasitic "n-channel" limited ION/I OFF ratio and sub-threshold swing, most likely due to effects from the InAs surface layer.

Micropore and nanopore fabrication in hollow antiresonant reflecting optical waveguides

PubMed Central

Holmes, Matthew R.; Shang, Tao; Hawkins, Aaron R.; Rudenko, Mikhail; Measor, Philip; Schmidt, Holger

2011-01-01

We demonstrate the fabrication of micropore and nanopore features in hollow antiresonant reflecting optical waveguides to create an electrical and optical analysis platform that can size select and detect a single nanoparticle. Micropores (4 μm diameter) are reactive-ion etched through the top SiO2 and SiN layers of the waveguides, leaving a thin SiN membrane above the hollow core. Nanopores are formed in the SiN membranes using a focused ion-beam etch process that provides control over the pore size. Openings as small as 20 nm in diameter are created. Optical loss measurements indicate that micropores did not significantly alter the loss along the waveguide. PMID:21922035

Micropore and nanopore fabrication in hollow antiresonant reflecting optical waveguides.

PubMed

Holmes, Matthew R; Shang, Tao; Hawkins, Aaron R; Rudenko, Mikhail; Measor, Philip; Schmidt, Holger

2010-01-01

We demonstrate the fabrication of micropore and nanopore features in hollow antiresonant reflecting optical waveguides to create an electrical and optical analysis platform that can size select and detect a single nanoparticle. Micropores (4 μm diameter) are reactive-ion etched through the top SiO(2) and SiN layers of the waveguides, leaving a thin SiN membrane above the hollow core. Nanopores are formed in the SiN membranes using a focused ion-beam etch process that provides control over the pore size. Openings as small as 20 nm in diameter are created. Optical loss measurements indicate that micropores did not significantly alter the loss along the waveguide.

Phosphorus oxide gate dielectric for black phosphorus field effect transistors

NASA Astrophysics Data System (ADS)

Dickerson, W.; Tayari, V.; Fakih, I.; Korinek, A.; Caporali, M.; Serrano-Ruiz, M.; Peruzzini, M.; Heun, S.; Botton, G. A.; Szkopek, T.

2018-04-01

The environmental stability of the layered semiconductor black phosphorus (bP) remains a challenge. Passivation of the bP surface with phosphorus oxide, POx, grown by a reactive ion etch with oxygen plasma is known to improve photoluminescence efficiency of exfoliated bP flakes. We apply phosphorus oxide passivation in the fabrication of bP field effect transistors using a gate stack consisting of a POx layer grown by reactive ion etching followed by atomic layer deposition of Al2O3. We observe room temperature top-gate mobilities of 115 cm2 V-1 s-1 in ambient conditions, which we attribute to the low defect density of the bP/POx interface.

Copper-assisted, anti-reflection etching of silicon surfaces

DOEpatents

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.

Nanoporous Silicon Carbide for Nanoelectromechanical Systems Applications

NASA Technical Reports Server (NTRS)

Hossain, T.; Khan, F.; Adesida, I.; Bohn, P.; Rittenhouse, T.; Lienhard, Michael (Technical Monitor)

2003-01-01

A major goal of this project is to produce porous silicon carbide (PSiC) via an electroless process for eventual utilization in nanoscale sensing platforms. Results in the literature have shown a variety of porous morphologies in SiC produced in anodic cells. Therefore, predictability and reproducibility of porous structures are initial concerns. This work has concentrated on producing morphologies of known porosity, with particular attention paid toward producing the extremely high surface areas required for a porous flow sensor. We have conducted a parametric study of electroless etching conditions and characteristics of the resulting physical nanostructure and also investigated the relationship between morphology and materials properties. Further, we have investigated bulk etching of SiC using both photo-electrochemical etching and inductively-coupled-plasma reactive ion etching techniques.

Plasma etching of superconducting Niobium tips for scanning tunneling microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roychowdhury, A.; Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742; Dana, R.

We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 μm diameter are dry etched in an SF₆ plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100),more » and Nb(100), as well as a doped topological insulator Bi₂Se₃ at temperatures ranging from 30 mK to 9 K.« less

Etching Enhancement Followed by Nitridation on Low-k SiOCH Film in Ar/C5F10O Plasma

NASA Astrophysics Data System (ADS)

Miyawaki, Yudai; Shibata, Emi; Kondo, Yusuke; Takeda, Keigo; Kondo, Hiroki; Ishikawa, Kenji; Okamoto, Hidekazu; Sekine, Makoto; Hori, Masaru

2013-02-01

The etching rates of low-dielectric-constant (low-k), porous SiOCH (p-SiOCH) films were increased by nitrogen-added Ar/C5F10O plasma etching in dual-frequency (60 MHz/2 MHz)-excited parallel plate capacitively coupled plasma. Previously, perfluoropropyl vinyl ether [C5F10O] provided a very high density of CF3+ ions [Nagai et al.: Jpn. J. Appl. Phys. 45 (2006) 7100]. Surface nitridation on the p-SiOCH surface exposed to Ar/N2 plasma led to the etching of larger amounts of p-SiOCH in Ar/C5F10O plasma, which depended on the formation of bonds such as =C(sp2)=N(sp2)- and -C(sp)≡N(sp).

Laser-Induced Fluorescence Helps Diagnose Plasma Processes

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Mattosian, J. N.; Gaeta, C. J.; Turley, R. S.; Williams, J. D.; Williamson, W. S.

1994-01-01

Technique developed to provide in situ monitoring of rates of ion sputter erosion of accelerator electrodes in ion thrusters also used for ground-based applications to monitor, calibrate, and otherwise diagnose plasma processes in fabrication of electronic and optical devices. Involves use of laser-induced-fluorescence measurements, which provide information on rates of ion etching, inferred rates of sputter deposition, and concentrations of contaminants.

The effect of axial ion parameters on the properties of glow discharge polymer in T2B/H2 plasma

NASA Astrophysics Data System (ADS)

Ai, Xing; He, Xiao-Shan; Huang, Jing-Lin; He, Zhi-Bing; Du, Kai; Chen, Guo

2018-03-01

Glow discharge polymer (GDP) films were fabricated using plasma-enhanced chemical vapor deposition. The main purpose of this work was to explore the correlations of plasma parameters with the surface morphology and chemical structure of GDP films. The intensities of main positive ions and ion energy as functions of axial distances in T2B/H2 plasma were diagnosed using energy-resolved mass spectrometry. The surface morphology and chemical structure were characterized as functions of axial distances using a scanning electron microscope and Fourier transform infrared spectroscopy, respectively. As the axial distance increases, both the intensities of positive ions and high energy ions decreases, and dissociation weakens while polymerization enhances. This leads to the weakening of the cross-linking structure of GDP films and the formation of dome defects on films. Additionally, high energy ions could introduce a strong etching effect to form etching pits. Therefore, an axial distance of about 20 mm was found to be the optimal plasma parameter to prepare the defect-free GDP films. These results could help one to find the optimal plasma parameters for GDP film deposition.

Nanofabrication and ion milling introduced effects on magnetic properties in magnetic recording

NASA Astrophysics Data System (ADS)

Sun, Zhenzhong

Perpendicular magnetic nanostructures have played an important role in magnetic recording technologies. In this dissertation, a systematic study on the CoPt magnetic nanostructures from fabrication, characterization to computer simulation has been performed. During the fabrication process, ion irradiation/bombardment in ion mill can cause physical damage to the magnetic nanostructures and degrade their magnetic properties. To study the effect of ion damage on CoPt nanostructures, different degrees of ion damage are introduced into CoPt nanopillars by varying the accelerating voltage in ion mill. The results demonstrate that the ion damage can reduce the coercivity by softening circumferential edge, and therefore changes the switching mechanism from coherent rotation to nucleation followed by rapid domain wall propagation. The SFD of CoPt nanostructures is independent of ion damage and is mainly determined by the intrinsic anisotropy distribution of the film rather than the nanostructure size distribution. Anisotropy-graded bit-patterned media are fabricated and studied based on high anisotropy L10-FePt material system. L10-FePt thin films with linearly and quadratically distributed anisotropy are achieved by varying substrate temperature during film growth. After patterning, the anisotropy-graded L10-FePt nanopillars display a reduced switching field and maintain a good thermal stability compared to the non-graded one. Experimental investigation and comparison further prove the concept of "anisotropy-graded" bit-patterned media and their potential application in the future magnetic recording. During magnetic write head fabrication, ion-beam damage may degrade the performance of the magnetic write pole. A surface sensitive MOKE is used to characterize the magnetic properties of these etched FeCo films. MOKE measurement shows a hard axis hysteresis loop with a high Mr in the high power etched film due to the ion beam introduced defects. The high power etched film also shows the highest RMS by AFM measurement. The geometric peaks at the top surface may have shape anisotropy and serve as the pinning sites. These magnetic pinning sites can prevent the nucleation center forming at the top surface during the switching process and lead to a high Mr in the top surface region.

Electron microscope aperture system

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1976-01-01

An electron microscope including an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen, and an objective lens having an annular objective aperture, for focusing electrons passing through the specimen onto an image plane are described. The invention also entails a method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques.

A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer

NASA Astrophysics Data System (ADS)

Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, Nosoung; Ko, Heung Cho; Jung, Gun Young

2015-08-01

Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02786a

Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V.

2017-02-15

The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due tomore » the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.« less

Morphologies of Solid Surfaces Produced Far from Equilibrium

DTIC Science & Technology

1991-03-10

common to all these applications is that thc surface preparation processes used are far from chemical equilibrium. Many of the processes involve an...energetic ion beam, plasma or gas that is used to modify a surface, either by etching or depositing material. The electrical, optical and mechanical...growth, a number of continuum models have been used in the materials science literature, in particular in the context of electron-beam etching of

Silicon Nanostructures, Excitonic Interactions, Laser Consequences

DTIC Science & Technology

2008-07-11

etching using an anodized aluminum oxide membrane as mask. The results described here lay a solid foundation for the next phase of development aimed at...achieved though reactive-ion-etching using an anodized aluminum oxide membrane as mask. The results described here lay a solid foundation for the next...Materials, April 4, 2006 issue). 6. Aijun Yin, Marian Tzolov, David Cardimona and Jimmy Xu, "Fabrication of Highly Ordered Anodic Aluminum Oxide

Surface photovoltage studies of p-type AlGaN layers after reactive-ion etching

NASA Astrophysics Data System (ADS)

McNamara, J. D.; Phumisithikul, K. L.; Baski, A. A.; Marini, J.; Shahedipour-Sandvik, F.; Das, S.; Reshchikov, M. A.

2016-10-01

The surface photovoltage (SPV) technique was used to study the surface and electrical properties of Mg-doped, p-type AlxGa1-xN (0.06 < x < 0.17) layers. SPV measurements reveal significant deviation from previous SPV studies on p-GaN:Mg thin films and from the predictions of a thermionic model for the SPV behavior. In particular, the SPV of the p-AlGaN:Mg layers exhibited slower-than-expected transients under ultraviolet illumination and delayed restoration to the initial dark value. The slow transients and delayed restorations can be attributed to a defective surface region which interferes with normal thermionic processes. The top 45 nm of the p-AlGaN:Mg layer was etched using a reactive-ion etch which caused the SPV behavior to be substantially different. From this study, it can be concluded that a defective, near-surface region is inhibiting the change in positive surface charge by allowing tunneling or hopping conductivity of holes from the bulk to the surface, or by the trapping of electrons traveling to the surface by a high concentration of defects in the near-surface region. Etching removes the defective layer and reveals a region of presumably higher quality, as evidenced by substantial changes in the SPV behavior.

Durability to oxygen reactive ion etching enhanced by addition of synthesized bis(trimethylsilyl)phenyl-containing (meth)acrylates in ultraviolet nanoimprint lithography

NASA Astrophysics Data System (ADS)

Ito, Shunya; Sato, Hiroki; Tasaki, Yuhei; Watanuki, Kimihito; Nemoto, Nobukatsu; Nakagawa, Masaru

2016-06-01

We investigated the selection of bis(trimethylsilyl)phenyl-containing (meth)acrylates as additives to improve the durability to oxygen reactive ion etching (O2 RIE) of sub-50 nm imprint resist patterns suitable for bubble-defect-free UV nanoimprinting with a readily condensable gas. 2,5-Bis(2-acryloyloxyethoxy)-1,4-bis(trimethylsilyl)benzene, which has a diacrylate chemical structure similar to that of glycerol 1,3-diglycerolate diacrylate used as a base monomer, and 3-(2-methacryloyloxyethoxy)-1-(hydroxylethoxy)-2-propoxy-3,5-bis(trimethylsilyl)benzene, which has a hydroxy group similar to the base monomer, were synthesized taking into consideration the Ohnishi and ring parameters, and the oxidization of the trimethylsilyl moiety to inorganic species during O2 RIE. The addition of the latter liquid additive to the base monomer decreased etching rate owing to the good miscibility of the additive in the base monomer, while the addition of the former crystalline additive caused phase separation after UV nanoimprinting. The latter additive worked as a compatibilizer to the former additive, which is preferred for etching durability improvement. The coexistence of the additives enabled the fabrication of a 45 nm line-and-space resist pattern by UV nanoimprinting, and its residual layer could be removed by O2 RIE.

Diffusion kinetics of the glucose/glucose oxidase system in swift heavy ion track-based biosensors

NASA Astrophysics Data System (ADS)

Fink, Dietmar; Vacik, Jiri; Hnatowicz, V.; Muñoz Hernandez, G.; Garcia Arrelano, H.; Alfonta, Lital; Kiv, Arik

2017-05-01

For understanding of the diffusion kinetics and their optimization in swift heavy ion track-based biosensors, recently a diffusion simulation was performed. This simulation aimed at yielding the degree of enrichment of the enzymatic reaction products in the highly confined space of the etched ion tracks. A bunch of curves was obtained for the description of such sensors that depend only on the ratio of the diffusion coefficient of the products to that of the analyte within the tracks. As hitherto none of these two diffusion coefficients is accurately known, the present work was undertaken. The results of this paper allow one to quantify the previous simulation and hence yield realistic predictions of glucose-based biosensors. At this occasion, also the influence of the etched track radius on the diffusion coefficients was measured and compared with earlier prediction.

Field emitter arrays and displays produced by ion tracking lithography

NASA Astrophysics Data System (ADS)

Felter, T. E.; Musket, R. G.; Bernhardt, A. F.

2005-12-01

When ions of sufficient electronic energy loss traverse a dielectric film or foil, they alter the chemical bonding along their nominally straight path within the material. A suitable etchant can quickly dissolve these so-called latent tracks leaving holes of small diameter (∼10 nm) but long length - several microns. Continuing the etching process gradually increases the diameter reproducibly and uniformly. The trackable medium can be applied as a uniform film onto large substrates. The small, monodisperse holes produced by this track etching can be used in conjunction with additional thin film processing to create functional structures attached to the substrate. For example, Lawrence Livermore National Laboratory and Candescent Technologies Corporation (CTC) co-developed a process to make arrays of gated field emitters (∼100 nm diameter electron guns) for CTC's Thin CRTTM displays, which have been fabricated to diagonal dimensions >13 in. Additional technological applications of ion tracking lithography will be briefly covered.

Kinked silicon nanowires-enabled interweaving electrode configuration for lithium-ion batteries.

PubMed

Sandu, Georgiana; Coulombier, Michael; Kumar, Vishank; Kassa, Hailu G; Avram, Ionel; Ye, Ran; Stopin, Antoine; Bonifazi, Davide; Gohy, Jean-François; Leclère, Philippe; Gonze, Xavier; Pardoen, Thomas; Vlad, Alexandru; Melinte, Sorin

2018-06-28

A tri-dimensional interweaving kinked silicon nanowires (k-SiNWs) assembly, with a Ni current collector co-integrated, is evaluated as electrode configuration for lithium ion batteries. The large-scale fabrication of k-SiNWs is based on a procedure for continuous metal assisted chemical etching of Si, supported by a chemical peeling step that enables the reuse of the Si substrate. The kinks are triggered by a simple, repetitive etch-quench sequence in a HF and H 2 O 2 -based etchant. We find that the inter-locking frameworks of k-SiNWs and multi-walled carbon nanotubes exhibit beneficial mechanical properties with a foam-like behavior amplified by the kinks and a suitable porosity for a minimal electrode deformation upon Li insertion. In addition, ionic liquid electrolyte systems associated with the integrated Ni current collector repress the detrimental effects related to the Si-Li alloying reaction, enabling high cycling stability with 80% capacity retention (1695 mAh/g Si ) after 100 cycles. Areal capacities of 2.42 mAh/cm 2 (1276 mAh/g electrode ) can be achieved at the maximum evaluated thickness (corresponding to 1.3 mg Si /cm 2 ). This work emphasizes the versatility of the metal assisted chemical etching for the synthesis of advanced Si nanostructures for high performance lithium ion battery electrodes.

Atomic layer deposition frequency-multiplied Fresnel zone plates for hard x-rays focusing

DOE PAGES

Moldovan, Nicolaie; Divan, Ralu; Zeng, Hongjun; ...

2017-12-01

The design and fabrication of Fresnel zone plates for hard x-ray focusing up to 25 keV photon energies with better than 50 nm imaging half-pitch resolution is reported as performed by forming an ultrananocrystalline diamond (UNCD) scaffold, subsequently coating it with atomic layer deposition (ALD) with an absorber/phase shifting material, followed by back side etching of Si to form a diamond membrane device. The scaffold is formed by chemical vapor-deposited UNCD, electron beam lithography, and deep-reactive ion etching of diamond to desired specifications. The benefits of using diamond are as follows: improved mechanical robustness to prevent collapse of high-aspect-ratio ringmore » structures, a known high-aspect-ratio etch method, excellent radiation hardness, extremely low x-ray absorption, and significantly improved thermal/dimensional stability as compared to alternative materials. Central to the technology is the high-resolution patterning of diamond membranes at wafer scale, which was pushed to 60 nm lines and spaces etched 2.2-mu m-deep, to an aspect ratio of 36:1. The absorber growth was achieved by ALD of Ir, Pt, or W, while wafer-level processing allowed to obtain up to 121 device chips per 4 in. wafer with yields better than 60%. X-ray tests with such zone plates allowed resolving 50 nm lines and spaces, at the limit of the available resolution test structures.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moldovan, Nicolaie; Divan, Ralu; Zeng, Hongjun

The design and fabrication of Fresnel zone plates for hard x-ray focusing up to 25 keV photon energies with better than 50 nm imaging half-pitch resolution is reported as performed by forming an ultrananocrystalline diamond (UNCD) scaffold, subsequently coating it with atomic layer deposition (ALD) with an absorber/phase shifting material, followed by back side etching of Si to form a diamond membrane device. The scaffold is formed by chemical vapor-deposited UNCD, electron beam lithography, and deep-reactive ion etching of diamond to desired specifications. The benefits of using diamond are as follows: improved mechanical robustness to prevent collapse of high-aspect-ratio ringmore » structures, a known high-aspect-ratio etch method, excellent radiation hardness, extremely low x-ray absorption, and significantly improved thermal/dimensional stability as compared to alternative materials. Central to the technology is the high-resolution patterning of diamond membranes at wafer scale, which was pushed to 60 nm lines and spaces etched 2.2-mu m-deep, to an aspect ratio of 36:1. The absorber growth was achieved by ALD of Ir, Pt, or W, while wafer-level processing allowed to obtain up to 121 device chips per 4 in. wafer with yields better than 60%. X-ray tests with such zone plates allowed resolving 50 nm lines and spaces, at the limit of the available resolution test structures.« less

Anisotropic etching of amorphous perfluoropolymer films in oxygen-based inductively coupled plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ono, Takao; Akagi, Takanori; Center for NanoBio Integration, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656

2009-01-01

An amorphous perfluoropolymer, 'Cytop' (Asahi Glass Co., Ltd.), is a preferable material for the fabrication of micro total analysis system devices because of its superior optical transparency over a wide wavelength range and low refractive index of 1.34, which is almost the same as that of water, as well as excellent chemical stability. To establish the precise microfabrication technology for this unique resin, the dry etching of the amorphous perfluoropolymer in Ar/O{sub 2} low-pressure inductively coupled plasma has been studied. A relatively high etch rate of approximately 6.3 {mu}m/min at maximum and highly anisotropic etched features was attained. Plasma measurementsmore » by a single Langmuir probe technique and actinometry revealed that etching is dominated by ion-assisted surface desorption above a 10%O{sub 2} mixing ratio, whereas the supply of active oxygen species is the rate-limiting process below 10%. Moreover, angled x-ray photoelectron spectroscopy measurements of an etched trench pattern revealed that a high anisotropy is attributed to the formation of a carbon-rich sidewall protection layer.« less

Preparation and performance of broadband antireflective sub-wavelength structures on Ge substrate

NASA Astrophysics Data System (ADS)

Shen, Xiang-Wei; Liu, Zheng-Tang; Li, Yang-Ping; Lu, Hong-Cheng; Xu, Qi-Yuan; Liu, Wen-Ting

2009-01-01

Sub-wavelength structures (SWS) were prepared on Ge substrates through photolithography and reactive ion etching (RIE) technology for broadband antireflective purposes in the long wave infrared (LWIR) waveband of 8-12 μm. Topography of the etched patterns was observed using high resolution optical microscope and atomic force microscope (AFM). Infrared transmission performance of the SWS was investigated by Fourier transform infrared (FTIR) spectrometer. Results show that the etched patterns were of high uniformity and fidelity, the SWS exhibited a good broadband antireflective performance with the increment of the average transmittance which is over 8-12 μm up to 8%.

Low-Power RIE of SiO2 in CHF3 To Obtain Steep Sidewalls

NASA Technical Reports Server (NTRS)

Turner, Tasha; Wu, Chi

2003-01-01

A reactive-ion etching (RIE) process has been developed to enable the formation of holes with steep sidewalls in a layer of silicon dioxide that covers a silicon substrate. The holes in question are through the thickness of the SiO2 and are used to define silicon substrate areas to be etched or to be built upon through epitaxial deposition of silicon. The sidewalls of these holes are required to be vertical in order to ensure that the sidewalls of the holes to be etched in the substrate or the sidewalls of the epitaxial deposits, respectively, also turn out to be vertical.

Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors

NASA Astrophysics Data System (ADS)

Sohrabi, Mehdi

2017-11-01

A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors.

PubMed

Sohrabi, Mehdi

2017-11-01

A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

Method to control artifacts of microstructural fabrication

DOEpatents

Shul, Randy J.; Willison, Christi G.; Schubert, W. Kent; Manginell, Ronald P.; Mitchell, Mary-Anne; Galambos, Paul C.

2006-09-12

New methods for fabrication of silicon microstructures have been developed. In these methods, an etching delay layer is deposited and patterned so as to provide differential control on the depth of features being etched into a substrate material. Compensation for etching-related structural artifacts can be accomplished by proper use of such an etching delay layer.

Inverse metal-assisted chemical etching produces smooth high aspect ratio InP nanostructures.

PubMed

Kim, Seung Hyun; Mohseni, Parsian K; Song, Yi; Ishihara, Tatsumi; Li, Xiuling

2015-01-14

Creating high aspect ratio (AR) nanostructures by top-down fabrication without surface damage remains challenging for III-V semiconductors. Here, we demonstrate uniform, array-based InP nanostructures with lateral dimensions as small as sub-20 nm and AR > 35 using inverse metal-assisted chemical etching (I-MacEtch) in hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), a purely solution-based yet anisotropic etching method. The mechanism of I-MacEtch, in contrast to regular MacEtch, is explored through surface characterization. Unique to I-MacEtch, the sidewall etching profile is remarkably smooth, independent of metal pattern edge roughness. The capability of this simple method to create various InP nanostructures, including high AR fins, can potentially enable the aggressive scaling of InP based transistors and optoelectronic devices with better performance and at lower cost than conventional etching methods.

Development of Wien filter for small ion gun of surface analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahng, Jungbae; Busan Center, Korea Basic Science Institute, Busan 609-735; Hong, Jonggi

The gas cluster ion beam (GCIB) and liquid metal ion beam have been studied in the context of ion beam usage for analytical equipment in applications such as X-ray photoelectron spectroscopy and secondary ion mass spectroscopy (SIMS). In particular, small ion sources are used for the secondary ion generation and ion etching. To set the context to this study, the SIMS project has been launched to develop ion-gun based analytical equipment for the Korea Basic Science Institute. The objective of the first stage of the project is the generation of argon beams with a GCIB system [A. Kirkpatrick, Nucl. Instrum.more » Methods Phys. Res., Sect. B 206, 830–837 (2003)] that consists of a nozzle, skimmer, ionizer, acceleration tube, separation system, transport system, and target. The Wien filter directs the selected cluster beam to the target system by exploiting the velocity difference of the generated particles from GCIB. In this paper, we present the theoretical modeling and three-dimensional electromagnetic analysis of the Wien filter, which can separate Ar{sup +}{sub 2500} clusters from Ar{sup +}{sub 2400} to Ar{sup +}{sub 2600} clusters with a 1-mm collimator.« less

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.

Stability of field emission current from porous n-GaAs(110)

NASA Astrophysics Data System (ADS)

Tondare, V. N.; Naddaf, M.; Bhise, A. B.; Bhoraskar, S. V.; Joag, D. S.; Mandale, A. B.; Sainkar, S. R.

2002-02-01

Field electron emission from porous GaAs has been investigated. The emitter was prepared by anodic etching of n-GaAs (110) in 0.1 M HCl solution. The as-etched porous GaAs shows nonlinear Fowler-Nordheim (FN) characteristics, with a low onset voltage. The emitter, after operating for 6 h at the residual gas pressure of 1×10-8 mbar, shows a linear FN characteristics with a relatively high onset voltage and poor field emission current stability as compared to the as-etched emitter. The change in the behavior was attributed to the residual gas ion bombardment during field electron emission. X-ray photoelectron spectroscopic investigations were carried out on as-etched sample and the one which was studied for field emission. The studies indicate that the as-etched surface contains As2O3 and the surface after field electron emission for about 6 h becomes gallium rich. The presence of As2O3 seems to be a desirable feature for the stable field emission current.

Characteristics of n-GaN After Cl2/Ar and Cl2/N2 Inductively Coupled Plasma Etching

NASA Astrophysics Data System (ADS)

Han, Yan-Jun; Xue, Song; Guo, Wen-Ping; Sun, Chang-Zheng; Hao, Zhi-Biao; Luo, Yi

2003-10-01

A systematic study on the effect of inductively coupled plasma (ICP) etching on n-type GaN is presented. The optical and electrical properties and surface stoichiometry of n-type GaN are evaluated using room-temperature photoluminescence (PL) and current-voltage (I-V) characteristic measurements, and X-ray photoelectron spectroscopy (XPS), respectively. Investigation of the effect of additive gas (N2 and Ar) and RF power on these characteristics has also been carried out. It is shown that the decrease in the O/Ga ratio after ICP etching can suppress the deterioration of the near-band-edge emission intensity. Furthermore, N vacancy (VN) with a shallow donor nature and Ga vacancy (VGa) with a deep acceptor nature are generated after ICP etching upon the addition of Ar and N2 to Cl2 plasma, respectively. Lower ohmic contact resistance could be obtained when VN or ion-bombardment-induced defect is dominant at the surface. Improved etching conditions have been obtained based on these results.

Highly selective dry etching of GaP in the presence of AlxGa1–xP with a SiCl4/SF6 plasma

NASA Astrophysics Data System (ADS)

Hönl, Simon; Hahn, Herwig; Baumgartner, Yannick; Czornomaz, Lukas; Seidler, Paul

2018-05-01

We present an inductively coupled-plasma reactive-ion etching process that simultaneously provides both a high etch rate and unprecedented selectivity for gallium phosphide (GaP) in the presence of aluminum gallium phosphide (AlxGa1–xP). Utilizing mixtures of silicon tetrachloride (SiCl4) and sulfur hexafluoride (SF6), selectivities exceeding 2700:1 are achieved at GaP etch rates above 3000 nm min‑1. A design of experiments has been employed to investigate the influence of the inductively coupled-plasma power, the chamber pressure, the DC bias and the ratio of SiCl4 to SF6. The process enables the use of thin AlxGa1–xP stop layers even at aluminum contents of a few percent.

Deeply-etched micromirror with vertical slit and metallic coating enabling transmission-type optical MEMS filters

NASA Astrophysics Data System (ADS)

Othman, Muhammad A.; Sabry, Yasser M.; Sadek, Mohamed; Nassar, Ismail M.; Khalil, Diaa A.

2016-03-01

In this work we report a novel optical MEMS deeply-etched mirror with metallic coating and vertical slot, where the later allows reflection and transmission by the micromirror. The micromirror as well as fiber grooves are fabricated using deep reactive ion etching technology, where the optical axis is in-plane and the components are self-aligned. The etching depth is 150 μm chosen to improve the micromirror optical throughput. The vertical optical structure is Al metal coated using the shadow mask technique. A fiber-coupled Fabry-Pérot filter is successfully realized using the fabricated structure. Experimental measurements were obtained based on a dielectric-coated optical fiber inserted into a fiber groove facing the slotted micromirror. A versatile performance in terms of the free spectral range and 3-dB bandwidth is achieved.

Temperature dependence on plasma-induced damage and chemical reactions in GaN etching processes using chlorine plasma

NASA Astrophysics Data System (ADS)

Liu, Zecheng; Ishikawa, Kenji; Imamura, Masato; Tsutsumi, Takayoshi; Kondo, Hiroki; Oda, Osamu; Sekine, Makoto; Hori, Masaru

2018-06-01

Plasma-induced damage (PID) on GaN was optimally reduced by high-temperature chlorine plasma etching. Energetic ion bombardments primarily induced PID involving stoichiometry, surface roughness, and photoluminescence (PL) degradation. Chemical reactions under ultraviolet (UV) irradiation and chlorine radical exposure at temperatures higher than 400 °C can be controlled by taking into account the synergism of simultaneous photon and radical irradiations to effectively reduce PID.

Enhanced light output from the nano-patterned InP semiconductor substrate through the nanoporous alumina mask.

PubMed

Jung, Mi; Kim, Jae Hun; Lee, Seok; Jang, Byung Jin; Lee, Woo Young; Oh, Yoo-Mi; Park, Sun-Woo; Woo, Deokha

2012-07-01

A significant enhancement in the light output from nano-patterned InP substrate covered with a nanoporous alumina mask was observed. A uniform nanohole array on an InP semiconductor substrate was fabricated by inductively coupled plasma reactive ion etching (ICP-RIE), using the nanoporous alumina mask as a shadow mask. The light output property of the semiconductor substrate was investigated via photoluminescence (PL) intensity measurement. The InP substrate with a nanohole array showed a more enhanced PL intensity compared with the raw InP substrate without a nanohole structure. After ICP-RIE etching, the light output from the nanoporous InP substrate covered with a nanoporous alumina mask showed fourfold enhanced PL intensity compared with the raw InP substrate. These results can be used as a prospective method for increasing the light output efficiency of optoelectronic devices.

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.

Ionization chamber dosimeter

DOEpatents

Renner, Tim R.; Nyman, Mark A.; Stradtner, Ronald

1991-01-01

A method for fabricating an ion chamber dosimeter collecting array of the type utilizing plural discrete elements formed on a uniform collecting surface which includes forming a thin insulating layer over an aperture in a frame having surfaces, forming a predetermined pattern of through holes in the layer, plating both surfaces of the layer and simultaneously tilting and rotating the frame for uniform plate-through of the holes between surfaces. Aligned masking and patterned etching of the surfaces provides interconnects between the through holes and copper leads provided to external circuitry.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ast, D.G.

Research focused on control of misfit dislocations in strained epitaxial layers of GaAs through prepatterning of the substrate. Patterning and etching trenches into GaAs substrates before epitaxial growth results in nonplanar wafer surface, which makes device fabrication more difficult. Selective ion damaging the substrate prior to growth was investigated. The question of whether the overlayer must or must not be discontinuous was addressed. The third research direction was to extend results from molecular beam epitaxially grown material to organometallic chemical vapor deposition. Effort was increased to study the patterning processes and the damage it introduces into the substrate. The researchmore » program was initiated after the discovery that 500-eV dry etching in GaAs damages the substrate much deeper than the ion range.« less

Atomically Traceable Nanostructure Fabrication

PubMed Central

Ballard, Josh B.; Dick, Don D.; McDonnell, Stephen J.; Bischof, Maia; Fu, Joseph; Owen, James H. G.; Owen, William R.; Alexander, Justin D.; Jaeger, David L.; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J.; Wallace, Robert M.; Reidy, Richard; Silver, Richard M.; Randall, John N.; Von Ehr, James

2015-01-01

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure. PMID:26274555

Atomically Traceable Nanostructure Fabrication.

PubMed

Ballard, Josh B; Dick, Don D; McDonnell, Stephen J; Bischof, Maia; Fu, Joseph; Owen, James H G; Owen, William R; Alexander, Justin D; Jaeger, David L; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J; Wallace, Robert M; Reidy, Richard; Silver, Richard M; Randall, John N; Von Ehr, James

2015-07-17

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

Method of Forming Textured Silicon Substrate by Maskless Cryogenic Etching

NASA Technical Reports Server (NTRS)

Yee, Karl Y. (Inventor); Homyk, Andrew P. (Inventor)

2014-01-01

Disclosed herein is a textured substrate comprising a base comprising silicon, the base having a plurality of needle like structures depending away from the base, wherein at least one of the needle like structures has a depth of greater than or equal to about 50 micrometers determined perpendicular to the base, and wherein at least one of the needle like structures has a width of less than or equal to about 50 micrometers determined parallel to the base. An anode and a lithium ion battery comprising the textured substrate, and a method of producing the textured substrate are also disclosed.

Fabrication of p-type porous silicon nanowire with oxidized silicon substrate through one-step MACE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shaoyuan; Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093; Ma, Wenhui, E-mail: mwhsilicon@163.com

2014-05-01

In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO{sub 3} system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO{sub 3} concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWsmore » is significantly reduced when Ag{sup +} ions concentrations are too high. The deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon. - Graphical abstract: Schematic cross-sectional views of PSiNWs array formation by etching oxidized silicon wafer in HF/AgNO{sub 3} solution. (A) At the starting point; (B) during the etching process; and (C) after Ag dendrites remove. - Highlights: • Prior to etching, a simple pre-oxidation is firstly used to treat silicon substrate. • The medially doped p-type MPSiNWs are prepared by one-step MACE. • Deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon are studied. • A model is finally proposed to explain the formation mechanism of PSiNWs.« less

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.

Titanium hydride and hydrogen concentration in acid-etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems.

PubMed

Szmukler-Moncler, S; Bischof, M; Nedir, R; Ermrich, M

2010-09-01

Acid etching is a popular method to texture the surface of dental implants. During etching, the titanium oxide protective layer is dissolved and small native hydrogen ions diffuse into the unprotected implant surface. They enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH). The aim of this study was to measure the concentration of TiH at the implant surface and the total concentration of Hydrogen at five commercially available implant systems, made of either commercially pure (cp) titanium or titanium alloy. X-Ray diffraction (XRD) was conducted on each implant system to determine the compounds present at the implant surface. Following a TiH(2)/Ti calibration curve, the concentration of TiH was determined. Concentration of hydrogen in the implants was measured by the inert gas fusion thermal conductivity/infrared detection method. XRD data showed that TiH was present on all cp titanium implants but not on the alloyed implants. TiH concentration varied between 5% and 37%. Hydrogen concentration varied between 43 and 108 ppm, no difference in uptake was found between the cp titanium and alloyed implants. Low solubility of hydrogen in alpha-titanium is responsible for precipitation into TiH. Stronger etching conditions led to higher concentration of TiH2-x. High solubility of hydrogen in the beta-phase of the alloy is preventing hydrogen from precipitating into TiH. All implants, even those lacking TiH at the surface, were enriched with hydrogen. In all implants, hydrogen concentration was within the normative limit of 130 ppm.

Method to fabricate multi-level silicon-based microstructures via use of an etching delay layer

DOEpatents

Manginell, Ronald P.; Schubert, W. Kent; Shul, Randy J.

2005-08-16

New methods for fabrication of silicon microstructures have been developed. In these methods, an etching delay layer is deposited and patterned so as to provide differential control on the depth of features being etched into a substrate material. Structures having features with different depth can be formed thereby in a single etching step.

Uniformly thinned optical fibers produced via HF etching with spectral and microscopic verification.

PubMed

Bal, Harpreet K; Brodzeli, Zourab; Dragomir, Nicoleta M; Collins, Stephen F; Sidiroglou, Fotios

2012-05-01

A method for producing uniformly thinned (etched) optical fibers is described, which can also be employed to etch optical fibers containing a Bragg grating (FBG) uniformly for evanescent-field-based sensing and other applications. Through a simple modification of this method, the fabrication of phase-shifted FBGs based on uneven etching is also shown. The critical role of how a fiber is secured is shown, and the success of the method is illustrated, by differential interference contrast microscopy images of uniformly etched FBGs. An etched FBG sensor for the monitoring of the refractive index of different glycerin solutions is demonstrated.

Cryogenic plasma-processed silicon microspikes as a high-performance anode material for lithium ion-batteries

NASA Astrophysics Data System (ADS)

Sakai, Joe; Luais, Erwann; Wolfman, Jérôme; Tillocher, Thomas; Dussart, Rémi; Tran-Van, Francois; Ghamouss, Fouad

2017-10-01

Micro- or nano-structuring is essential in order to use Si as an anode material for lithium ion batteries. In the present study, we attempted to use Si wafers with a spiky microstructure (SMS), the so-called black-Si, prepared by a cryogenic reactive ion etching process with an SF6/O2 gas mixture, for Li half-cells. The SMS with various sizes of spikes from 2.0 μm (height) × 0.2 μm (width) to 21 μm × 1.0 μm was etched by varying the SF6/O2 gas flow ratio. An anode of SMS of 11 μm-height in average showed stable charge/discharge capacity and Coulombic efficiency higher than 99% for more than 300 cycles, causing no destruction to any part of the Si wafer. The spiky structure turned columnar after cycles, suggesting graded lithiation levels along the length. The present results suggest a strategy to utilize a wafer-based Si material for an anode of a lithium ion battery durable against repetitive lithiation/delithiation cycles.

Mechanism for Plasma Etching of Shallow Trench Isolation Features in an Inductively Coupled Plasma

NASA Astrophysics Data System (ADS)

Agarwal, Ankur; Rauf, Shahid; He, Jim; Choi, Jinhan; Collins, Ken

2011-10-01

Plasma etching for microelectronics fabrication is facing extreme challenges as processes are developed for advanced technological nodes. As device sizes shrink, control of shallow trench isolation (STI) features become more important in both logic and memory devices. Halogen-based inductively coupled plasmas in a pressure range of 20-60 mTorr are typically used to etch STI features. The need for improved performance and shorter development cycles are placing greater emphasis on understanding the underlying mechanisms to meet process specifications. In this work, a surface mechanism for STI etch process will be discussed that couples a fundamental plasma model to experimental etch process measurements. This model utilizes ion/neutral fluxes and energy distributions calculated using the Hybrid Plasma Equipment Model. Experiments are for blanket Si wafers in a Cl2/HBr/O2/N2 plasma over a range of pressures, bias powers, and flow rates of feedstock gases. We found that kinetic treatment of electron transport was critical to achieve good agreement with experiments. The calibrated plasma model is then coupled to a string-based feature scale model to quantify the effect of varying process parameters on the etch profile. We found that the operating parameters strongly influence critical dimensions but have only a subtle impact on the etch depths.

Rapid Prototyping across the Spectrum: RF to Optical 3D Electromagnetic Structures

DTIC Science & Technology

2015-11-17

34Imprintable, Bendable, and Shape-Conformable Polymer Electrolytes for Versatile-Shaped Lithium - Ion Batteries ," Advanced Materials, vol. 25, pp. 1395-1400...center; and (d) close-up of light aperture etched with a focused ion beam [104] ............ 22 Figure 16: (a) Conformal antenna patterned by...where the features are defined using focused ion beam milling (e.g. fishnet patterns) [20], standard micro-/nano- lithography processes that are

Photolithographic surface micromachining of polydimethylsiloxane (PDMS).

PubMed

Chen, Weiqiang; Lam, Raymond H W; Fu, Jianping

2012-01-21

A major technical hurdle in microfluidics is the difficulty in achieving high fidelity lithographic patterning on polydimethylsiloxane (PDMS). Here, we report a simple yet highly precise and repeatable PDMS surface micromachining method using direct photolithography followed by reactive ion etching (RIE). Our method to achieve surface patterning of PDMS applied an O(2) plasma treatment to PDMS to activate its surface to overcome the challenge of poor photoresist adhesion on PDMS for photolithography. Our photolithographic PDMS surface micromachining technique is compatible with conventional soft lithography techniques and other silicon-based surface and bulk micromachining methods. To illustrate the general application of our method, we demonstrated fabrication of large microfiltration membranes and free-standing beam structures in PDMS.

Photolithographic surface micromachining of polydimethylsiloxane (PDMS)

PubMed Central

Chen, Weiqiang; Lam, Raymond H. W.

2014-01-01

A major technical hurdle in microfluidics is the difficulty in achieving high fidelity lithographic patterning on polydimethylsiloxane (PDMS). Here, we report a simple yet highly precise and repeatable PDMS surface micromachining method using direct photolithography followed by reactive ion etching (RIE). Our method to achieve surface patterning of PDMS applied an O2 plasma treatment to PDMS to activate its surface to overcome the challenge of poor photoresist adhesion on PDMS for photolithography. Our photolithographic PDMS surface micromachining technique is compatible with conventional soft lithography techniques and other silicon-based surface and bulk micromachining methods. To illustrate the general application of our method, we demonstrated fabrications of large microfiltration membranes and free-standing beam structures in PDMS. PMID:22089984

Fabrication of a terahertz quantum-cascade laser with a double metal waveguide based on multilayer GaAs/AlGaAs heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khabibullin, R. A., E-mail: khabibullin@isvch.ru; Shchavruk, N. V.; Pavlov, A. Yu.

2016-10-15

The Postgrowth processing of GaAs/AlGaAs multilayer heterostructures for terahertz quantumcascade lasers (QCLs) are studied. This procedure includes the thermocompression bonding of In–Au multilayer heterostructures with a doped n{sup +}-GaAs substrate, mechanical grinding, and selective wet etching of the substrate, and dry etching of QCL ridge mesastripes through a Ti/Au metallization mask 50 and 100 μm wide. Reactive-ion-etching modes with an inductively coupled plasma source in a BCl{sub 3}/Ar gas mixture are selected to obtain vertical walls of the QCL ridge mesastripes with minimum Ti/Au mask sputtering.

Poly(silyl silane) homo and copolymers

DOEpatents

Zeigler, J.K.

1991-08-13

Poly(silyl silanes) have been prepared. They have high photosensitivity and excellent resistance to oxygen-reactive ion etching processes. They are useful as photodepolymerizable photoresists, barrier layers, etc.

Influence of application method on surface free-energy and bond strength of universal adhesive systems to enamel.

PubMed

Imai, Arisa; Takamizawa, Toshiki; Sai, Keiichi; Tsujimoto, Akimasa; Nojiri, Kie; Endo, Hajime; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2017-10-01

The aim of the present study was to determine the influence of different adhesive application methods and etching modes on enamel bond effectiveness of universal adhesives using shear bond strength (SBS) testing and surface free-energy (SFE) measurements. The adhesives Scotchbond Universal, All-Bond Universal, Adhese Universal, and G-Premio Bond were used. Prepared bovine enamel specimens were divided into four groups, based on type of adhesive, and subjected to the following surface treatments: (i) total-etch mode with active application; (ii) total-etch mode with inactive application; (iii) self-etch mode with active application; and (iv) self-etch mode with inactive application. Bonded specimens were subjected to SBS testing. The SFE of the enamel surfaces with adhesive was measured after rinsing with acetone and water. The SBS values in total-etch mode were significantly higher than those in self-etch mode. In total-etch mode, significantly lower SBS values were observed with active application compared with inactive application; in contrast, in self-etch mode there were no significant differences in SBS between active and inactive applications. A reduction in total SFE was observed for active application compared with inactive application. The interaction between etching mode and application method was statistically significant, and the application method significantly affected enamel bond strength in total-etch mode. © 2017 Eur J Oral Sci.

Process Development for Reactive-Ion Etching of Molybdenum Disulfide (MoS2) Utilizing a Poly(methyl methacrylate) (PMMA) Etch Mask

DTIC Science & Technology

2017-10-01

Mazzoni Oak Ridge Associated Universities (ORAU) Maryland, Belcamp, MD Robert A Burke General Technical Services , LLC, Wall Township, NJ Barbara M...of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services ...solvent, or sonication. However, by using these physical procedures, there is a larger risk that the quality and structural integrity of the 2-D layer may

Method for forming suspended micromechanical structures

DOEpatents

Fleming, James G.

2000-01-01

A micromachining method is disclosed for forming a suspended micromechanical structure from {111} crystalline silicon. The micromachining method is based on the use of anisotropic dry etching to define lateral features of the structure which are etched down into a {111}-silicon substrate to a first etch depth, thereby forming sidewalls of the structure. The sidewalls are then coated with a protection layer, and the substrate is dry etched to a second etch depth to define a spacing of the structure from the substrate. A selective anisotropic wet etchant (e.g. KOH, EDP, TMAH, NaOH or CsOH) is used to laterally undercut the structure between the first and second etch depths, thereby forming a substantially planar lower surface of the structure along a {111} crystal plane that is parallel to an upper surface of the structure. The lateral extent of undercutting by the wet etchant is controlled and effectively terminated by either timing the etching, by the location of angled {111}-silicon planes or by the locations of preformed etch-stops. This present method allows the formation of suspended micromechanical structures having large vertical dimensions and large masses while allowing for detailed lateral features which can be provided by dry etch definition. Additionally, the method of the present invention is compatible with the formation of electronic circuitry on the substrate.

Method of fabricating vertically aligned group III-V nanowires

DOEpatents

Wang, George T; Li, Qiming

2014-11-25

A top-down method of fabricating vertically aligned Group III-V micro- and nanowires uses a two-step etch process that adds a selective anisotropic wet etch after an initial plasma etch to remove the dry etch damage while enabling micro/nanowires with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The method enables the fabrication of nanowire lasers, LEDs, and solar cells.

Ion Energy and Ion Flux Distributions of CF4/Ar/O2 Inductively Coupled Plasmas in a GEC Cell

NASA Technical Reports Server (NTRS)

Rao, M. V. V. S.; Cruden, Brett; Sharma, Surendra; Meyyappan, Meyya

2001-01-01

Knowledge of ion kinetics in plasma processing gas mixtures, such as CF4:Ar:O2, is important for understanding plasma assisted etching and deposition of materials. Ion energies and ion fluxes were measured in this mixture for 80:10:10, 60:20:20, and 40:30:30 mixture ratios in the pressure range of 10-50 mTorr, and at 200 and 300 W of RF power. Ions from plasma, sampled through a 10 micron orifice in the center of the lower plane electrode, were energy and mass analyzed by a combination of electrostatic energy and quadrupole mass filters. CFx(+) (x = 1 - 3), F2(+), F(+), C(+) from CF4, Ar(+) from Ar, and O2(+) and O(+) from O2, and by-product ions SiFx(+)(x = 1 - 3) from etching of quartz coupling window, COFx(+)(x = 1 - 3), CO(+), CO2(+), and OF(+) were detected. In all conditions ion flux decreases with increase of pressure but increase with increase of RF power. Ar(+) signal decreases with increase of pressure while CF3(+), which is the dominant ion at all conditions, increases with increase in pressure. The loss mechanism for Ar(+) and increase of CF3(+) is due to large cross section for Ar(+) + CF4 yields Ar + CF3(+) + F. Ion energies, which range from 15-25 eV depending on plasma operating conditions, are nearly Gaussian. By-product ion signals are higher at lower pressures indicating stronger plasma interaction with quartz window.

Inductively Coupled Plasma and Electron Cyclotron Resonance Plasma Etching of InGaAlP Compound Semiconductor System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abernathy, C.R.; Hobson, W.S.; Hong, J.

1998-11-04

Current and future generations of sophisticated compound semiconductor devices require the ability for submicron scale patterning. The situation is being complicated since some of the new devices are based on a wider diversity of materials to be etched. Conventional IUE (Reactive Ion Etching) has been prevalent across the industry so far, but has limitations for materials with high bond strengths or multiple elements. IrI this paper, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma), for the etching of ternary compound semiconductors (InGaP, AIInP, AlGaP) which are employed for electronic devices like heterojunctionmore » bipolar transistors (HBTs) or high electron mobility transistors (HEMTs), and photonic devices such as light-emitting diodes (LEDs) and lasers. High density plasma sources, opeiating at lower pressure, are expected to meet target goals determined in terms of etch rate, surface morphology, surface stoichiometry, selectivity, etc. The etching mechanisms, which are described in this paper, can also be applied to other III-V (GaAs-based, InP-based) as well as III-Nitride since the InGaAIP system shares many of the same properties.« less

In-situ etch rate study of Hf{sub x}La{sub y}O{sub z} in Cl{sub 2}/BCl{sub 3} plasmas using the quartz crystal microbalance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchack, Nathan; Kim, Taeseung; Chang, Jane P., E-mail: jpchang@seas.ucla.edu

2015-05-15

The etch rate of Hf{sub x}La{sub y}O{sub z} films in Cl{sub 2}/BCl{sub 3} plasmas was measured in-situ in an inductively coupled plasma reactor using a quartz crystal microbalance and corroborated by cross-sectional SEM measurements. The etch rate depended on the ion energy as well as the plasma chemistry. In contrast to other Hf-based ternary oxides, the etch rate of Hf{sub x}La{sub y}O{sub z} films was higher in Cl{sub 2} than in BCl{sub 3}. In the etching of Hf{sub 0.25}La{sub 0.12}O{sub 0.63}, Hf appeared to be preferentially removed in Cl{sub 2} plasmas, per surface compositional analysis by x-ray photoelectron spectroscopy andmore » the detection of HfCl{sub 3} generation in mass spectroscopy. These findings were consistent with the higher etch rate of Hf{sub 0.25}La{sub 0.12}O{sub 0.63} than that of La{sub 2}O{sub 3}.« less

A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer.

PubMed

Lim, Namsoo; Pak, Yusin; Kim, Jin Tae; Hwang, Youngkyu; Lee, Ryeri; Kumaresan, Yogeenth; Myoung, NoSoung; Ko, Heung Cho; Jung, Gun Young

2015-08-28

Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate. Contact printing was performed on the sample with a pressure of 50 psi and a temperature of 120 °C to make a conformal contact of the AAO membrane mask to the Si substrate. The CF4 plasma etching was conducted to transfer nanopores onto the Si substrate through the PMMA interlayer. The introduced PMMA interlayer prevented unwanted surface etching of the Si substrate by eliminating the etching ions and radicals bouncing at the gap between the mask and the substrate, resulting in a smooth Si nanopore array.

Fourier Transform Infrared Absorption Spectroscopy of Gas-Phase and Surface Reaction Products during Si Etching in Inductively Coupled Cl2 Plasmas

NASA Astrophysics Data System (ADS)

Miyata, Hiroki; Tsuda, Hirotaka; Fukushima, Daisuke; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2011-10-01

A better understanding of plasma-surface interactions is indispensable during etching, including the behavior of reaction or etch products, because the products on surfaces and in the plasma are important in passivation layer formation through their redeposition on surfaces. In practice, the nanometer-scale control of plasma etching would still rely largely on such passivation layer formation as well as ion-enhanced etching on feature surfaces. This paper presents in situ Fourier transform infrared (FTIR) absorption spectroscopy of gas-phase and surface reaction products during inductively coupled plasma (ICP) etching of Si in Cl2. The observation was made in the gas phase by transmission absorption spectroscopy (TAS), and also on the substrate surface by reflection absorption spectroscopy (RAS). The quantum chemical calculation was also made of the vibrational frequency of silicon chloride molecules. The deconvolution of the TAS spectrum revealed absorption features of Si2Cl6 and SiClx (x = 1-3) as well as SiCl4, while that of the RAS spectrum revealed relatively increased absorption features of unsaturated silicon chlorides. A different behavior was also observed in bias power dependence between the TAS and RAS spectra.

Effect of the chamber wall on fluorocarbon-assisted atomic layer etching of SiO2 using cyclic Ar/C4F8 plasma

PubMed Central

Kawakami, Masatoshi; Metzler, Dominik; Li, Chen; Oehrlein, Gottlieb S.

2016-01-01

The authors studied the effect of the temperature and chemical state of the chamber wall on process performance for atomic layer etching of SiO2 using a steady-state Ar plasma, periodic injection of a defined number of C4F8 molecules, and synchronized plasma-based Ar+ ion bombardment. To evaluate these effects, the authors measured the quartz coupling window temperature. The plasma gas phase chemistry was characterized using optical emission spectroscopy. It was found that although the thickness of the polymer film deposited in each cycle is constant, the etching behavior changed, which is likely related to a change in the plasma gas phase chemistry. The authors found that the main gas phase changes occur after C4F8 injection. The C4F8 and the quartz window react and generate SiF and CO. The emission intensity changes with wall surface state and temperature. Therefore, changes in the plasma gas species generation can lead to a shift in etching performance during processing. During initial cycles, minimal etching is observed, while etching gradually increases with cycle number. PMID:27375342

A novel 2D silicon nano-mold fabrication technique for linear nanochannels over a 4 inch diameter substrate

PubMed Central

Yin, Zhifu; Qi, Liping; Zou, Helin; Sun, Lei

2016-01-01

A novel low-cost 2D silicon nano-mold fabrication technique was developed based on Cu inclined-deposition and Ar+ (argon ion) etching. With this technique, sub-100 nm 2D (two dimensional) nano-channels can be etched economically over the whole area of a 4 inch n-type <100> silicon wafer. The fabricating process consists of only 4 steps, UV (Ultraviolet) lithography, inclined Cu deposition, Ar+ sputter etching, and photoresist & Cu removing. During this nano-mold fabrication process, we investigated the influence of the deposition angle on the width of the nano-channels and the effect of Ar+ etching time on their depth. Post-etching measurements showed the accuracy of the nanochannels over the whole area: the variation in width is 10%, in depth it is 11%. However, post-etching measurements also showed the accuracy of the nanochannels between chips: the variation in width is 2%, in depth it is 5%. With this newly developed technology, low-cost and large scale 2D nano-molds can be fabricated, which allows commercial manufacturing of nano-components over large areas. PMID:26752559

Roughness measurement and ion-beam polishing of super-smooth optical surfaces of fused quartz and optical ceramics.

PubMed

Chkhalo, N I; Churin, S A; Pestov, A E; Salashchenko, N N; Vainer, Yu A; Zorina, M V

2014-08-25

The main problems and the approach used by the authors for roughness metrology of super-smooth surfaces designed for diffraction-quality X-ray mirrors are discussed. The limitations of white light interferometry and the adequacy of the method of atomic force microscopy for surface roughness measurements in a wide range of spatial frequencies are shown and the results of the studies of the effect of etching by argon and xenon ions on the surface roughness of fused quartz and optical ceramics, Zerodur, ULE and Sitall, are given. Substrates of fused quartz and ULE with the roughness, satisfying the requirements of diffraction-quality optics intended for working in the spectral range below 10 nm, are made.

RIE-based Pattern Transfer Using Nanoparticle Arrays as Etch Masks

NASA Astrophysics Data System (ADS)

Hogg, Chip; Majetich, Sara A.; Bain, James A.

2009-03-01

Nanomasking is used to transfer the pattern of a self-assembled array of nanoparticles into an underlying thin film, for potential use as bit-patterned media. We have used this process to investigate the limits of pattern transfer, as a function of gap size in the pattern. Reactive Ion Etching (RIE) is our chosen process, since the gaseous reaction products and high chemical selectivity are ideal features for etching very small gaps. Interstitial surfactant is removed with an O2 plasma, allowing the etchants to penetrate between the particles. Their pattern is transferred into an intermediate SiO2 mask using a CH4-based RIE. This patterned SiO2 layer is finally used as a mask for the MeOH-based RIE which patterns the magnetic film. We present cross-sectional TEM characterization of the etch profiles, as well as magnetic characterization of the film before and after patterning.

Deterministic Placement of Quantum-Size Controlled Quantum Dots for Seamless Top-Down Integration

DOE PAGES

Fischer, Arthur J.; Anderson, P. Duke; Koleske, Daniel D.; ...

2017-08-18

We demonstrate a new route toward the integration and deterministic placement of quantum dots (QDs) within prepatterned nanostructures. Using standard electron-beam lithography (EBL) and inductively coupled plasma reactive-ion etching (ICP-RIE), we fabricate arrays of nanowires on a III-nitride platform. Next, we integrate QDs of controlled size within the prepatterned nanowires using a bandgap-selective, wet-etching technique: quantum-size-controlled photoelectrochemical (QSC-PEC) etching. Low-temperature microphotoluminescence (μ-PL) measurements of individual nanowires reveal sharp spectral signatures, indicative of QD formation. Further, internal quantum efficiency (IQE) measurements reveal a near order of magnitude improvement in emitter efficiency following QSC-PEC etching. Finally, second-order cross-correlation (g(2)(0)) measurements of individualmore » QDs directly confirm nonclassical, antibunching behavior. Lastly, our results illustrate an exciting approach toward the top-down integration of nonclassical light sources within nanophotonic platforms.« less

Deterministic Placement of Quantum-Size Controlled Quantum Dots for Seamless Top-Down Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, Arthur J.; Anderson, P. Duke; Koleske, Daniel D.

We demonstrate a new route toward the integration and deterministic placement of quantum dots (QDs) within prepatterned nanostructures. Using standard electron-beam lithography (EBL) and inductively coupled plasma reactive-ion etching (ICP-RIE), we fabricate arrays of nanowires on a III-nitride platform. Next, we integrate QDs of controlled size within the prepatterned nanowires using a bandgap-selective, wet-etching technique: quantum-size-controlled photoelectrochemical (QSC-PEC) etching. Low-temperature microphotoluminescence (μ-PL) measurements of individual nanowires reveal sharp spectral signatures, indicative of QD formation. Further, internal quantum efficiency (IQE) measurements reveal a near order of magnitude improvement in emitter efficiency following QSC-PEC etching. Finally, second-order cross-correlation (g(2)(0)) measurements of individualmore » QDs directly confirm nonclassical, antibunching behavior. Lastly, our results illustrate an exciting approach toward the top-down integration of nonclassical light sources within nanophotonic platforms.« less

Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joglekar, S.; Azize, M.; Palacios, T.

Ohmic contacts fabricated by regrowth of n{sup +} GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend uponmore » the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.« less

Poly(silyl silane)homo and copolymers

DOEpatents

Zeigler, J.M.

1989-04-11

Poly(silyl silanes) have been prepared. They have high photosensitivity and show excellent resistance to oxygen-reactive ion etching processes. They are useful as photodepolymerizable photoresists, barrier layers, etc.

Effect of elastic strain redistribution on electronic band structures of compressively strained GaInAsP/InP membrane quantum wires

NASA Astrophysics Data System (ADS)

Ferdous, F.; Haque, A.

2007-05-01

The effect of redistribution of elastic strain relaxation on the energy band structures of GaInAsP/InP compressively strained membrane quantum wires fabricated by electron-beam lithography, reactive-ion etching and two-step epitaxial growth is theoretically studied using an 8-band k ṡp method. Anisotropic strain analysis by the finite element method shows that due to etching away the top and the bottom InP clad layers in membrane structures, redistribution of strain occurs. It is found that strain redistribution increases the effective bandgap of membrane quantum wire structures causing a blueshift of the emission frequency. Comparison with effective bandgap calculations neglecting confinement and band mixing demonstrates that neglect of these effects leads to an overestimation of the change in the bandgap. We have also investigated the effect of variation of wire width, barrier strain compensation, number of stacked quantum wire layers, and thickness of the top and the bottom residual InP layers in membrane structures on the change in the effective bandgap of membrane structures.

Negative charge emission due to excimer laser bombardment of sodium trisilicate glass

NASA Astrophysics Data System (ADS)

Langford, S. C.; Jensen, L. C.; Dickinson, J. T.; Pederson, L. R.

1990-10-01

We describe measurements of negative charge emission accompanying irradiation of sodium trisilicate glass (Na2Oṡ3SiO2) with 248-nm excimer laser light at fluences on the order of 2 J/cm2 per pulse, i.e., at the threshold for ablative etching of the glass surface. The negative charge emission consists of a very prompt photoelectron burst coincident with the laser pulse, followed by a much slower plume of electrons and negative ions traveling with a high density cloud of positive ions, previously identified as primarily Na+. Using combinations of E and B fields in conjunction with time-of-flight methods, the negative ions were successfully separated from the plume and tentatively identified as O-, Si-, NaO-, and perhaps NaSi-. These negative species are probably formed by gas phase collisions in the near-surface region which result in electron attachment.

Graphene on silicon dioxide via carbon ion implantation in copper with PMMA-free transfer

NASA Astrophysics Data System (ADS)

Lehnert, Jan; Spemann, Daniel; Hamza Hatahet, M.; Mändl, Stephan; Mensing, Michael; Finzel, Annemarie; Varga, Aron; Rauschenbach, Bernd

2017-06-01

In this work, a synthesis method for the growth of low-defect large-area graphene using carbon ion beam implantation into metallic Cu foils is presented. The Cu foils (1 cm2 in size) were pre-annealed in a vacuum at 950 °C for 2 h, implanted with 35 keV carbon ions at room temperature, and subsequently annealed at 850 °C for 2 h to form graphene layers with the layer number controlled by the implantation fluence. The graphene was then transferred to SiO2/Si substrates by a PMMA-free wet chemical etching process. The obtained regions of monolayer graphene are of ˜900 μm size. Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and optical microscopy performed at room temperature demonstrated a good quality and homogeneity of the graphene layers, especially for monolayer graphene.

Plasma chemistry study of PLAD processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin Shu; Brumfield, Kyle; Liu, Lequn Jennifer

2012-11-06

Plasma doping (PLAD) shows very different impurity profiles compared to the conventional beam-line-based ion implantations due to its non-mass separation property and plasma environment. There is no simulation for PLAD process so far due to a lack of a dopant profile model. Several factors determine impurity profiles of PLAD process. The most significant factors are: plasma chemistry and deposition/etching characteristics of multi-ion species plasmas. In this paper, we present plasma chemistry and deposition/etching characteristics of PLAD processes versus co-gas dilutions. Four dopant plasmas including B{sub 2}H{sub 6}, BF{sub 3}, AsH{sub 3}, and PH{sub 3}, and two non-dopant plasmas including CH{submore » 4} and GeH{sub 4} are studied and demonstrated.« less

Simultaneous ion sputter polishing and deposition

NASA Technical Reports Server (NTRS)

Rutledge, S.; Banks, B.; Brdar, M.

1981-01-01

Results of experiments to study ion beam sputter polishing in conjunction with simultaneous deposition as a mean of polishing copper surfaces are presented. Two types of simultaneous ion sputter polishing and deposition were used in these experiments. The first type utilized sputter polishing simultaneous with vapor deposition, and the second type utilized sputter polishing simultaneous with sputter deposition. The etch and deposition rates of both techniques were studied, as well as the surface morphology and surface roughness.

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. Appendix.

DTIC Science & Technology

1987-12-31

CuCl Excimer Si x Ge Quadropole mass spectrometer ions photoionic emission, threshold low temperature processing low energy ion beam silicon oxidation ...Etching," ECS Proceedings, 1986. C. F. Yu, M. T. Schmidt, D. V. Podlesnik, and R. M. Osgood, "Optically-Induced, Room- Temperature Oxidation of Gallium...MOS transistors with gate dielectrics obtained by ion beam oxidation at room temperature . Introduction control over the process parameters and

Depth enhancement of ion sensitized data

DOEpatents

Lamartine, Bruce C.

2001-01-01

A process of fabricating a durable data storage medium is disclosed, the durable data storage medium capable of storing, digital or alphanumeric characters as well as graphical shapes or characters. Additionally, a durable data storage medium including a substrate having etched characters therein is disclosed, the substrate characterized as containing detectable residual amounts of ions used in the preparation process.

Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining

PubMed Central

Choi, Woong-Kirl; Kim, Seong-Hyun; Choi, Seung-Geon; Lee, Eun-Sang

2018-01-01

Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs) contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks. PMID:29351235

Highly selective SiO2 etching over Si3N4 using a cyclic process with BCl3 and fluorocarbon gas chemistries

NASA Astrophysics Data System (ADS)

Matsui, Miyako; Kuwahara, Kenichi

2018-06-01

A cyclic process for highly selective SiO2 etching with atomic-scale precision over Si3N4 was developed by using BCl3 and fluorocarbon gas chemistries. This process consists of two alternately performed steps: a deposition step using BCl3 mixed-gas plasma and an etching step using CF4/Ar mixed-gas plasma. The mechanism of the cyclic process was investigated by analyzing the surface chemistry at each step. BCl x layers formed on both SiO2 and Si3N4 surfaces in the deposition step. Early in the etching step, the deposited BCl x layers reacted with CF x radicals by forming CCl x and BF x . Then, fluorocarbon films were deposited on both surfaces in the etching step. We found that the BCl x layers formed in the deposition step enhanced the formation of the fluorocarbon films in the CF4 plasma etching step. In addition, because F radicals that radiated from the CF4 plasma reacted with B atoms while passing through the BCl x layers, the BCl x layers protected the Si3N4 surface from F-radical etching. The deposited layers, which contained the BCl x , CCl x , and CF x components, became thinner on SiO2 than on Si3N4, which promoted the ion-assisted etching of SiO2. This is because the BCl x component had a high reactivity with SiO2, and the CF x component was consumed by the etching reaction with SiO2.

Sensors and Micromachined Devices for the Automotive and New Markets: The Delphi Delco Electronics MEMS Story.

NASA Astrophysics Data System (ADS)

Logsdon, James

2002-03-01

This presentation will provide a brief history of the development of MEMS products and technology, beginning with the manifold absolute pressure sensor in the late seventies through the current variety of Delphi Delco Electronics sensors available today. The technology development of micromachining from uncompensated P plus etch stops to deep reactive ion etching and the technology development of wafer level packaging from electrostatic bonding to glass frit sealing and silicon to silicon direct bonding will be reviewed.

Nuclear tracks in lunar samples

NASA Technical Reports Server (NTRS)

Price, P. B.

1971-01-01

An attempt is made to relate the appearance of an etched tract to the atomic number and velocity of the ion that left it using 10 MeV/nucleon Kr beams and 6 MeV/nucleon Zn beams. It was found that the etching rate along a tract in minerals and glass is a monototonic function of ionization rate thus, making particle identification possible. Results show the following were present in lunar samples: superheavy elements, cosmic rays with z greater than 26, and solar flare particles in Surveyor glass.

Atomic-layer soft plasma etching of MoS2

PubMed Central

Xiao, Shaoqing; Xiao, Peng; Zhang, Xuecheng; Yan, Dawei; Gu, Xiaofeng; Qin, Fang; Ni, Zhenhua; Han, Zhao Jun; Ostrikov, Kostya (Ken)

2016-01-01

Transition from multi-layer to monolayer and sub-monolayer thickness leads to the many exotic properties and distinctive applications of two-dimensional (2D) MoS2. This transition requires atomic-layer-precision thinning of bulk MoS2 without damaging the remaining layers, which presently remains elusive. Here we report a soft, selective and high-throughput atomic-layer-precision etching of MoS2 in SF6 + N2 plasmas with low-energy (<0.4 eV) electrons and minimized ion-bombardment-related damage. Equal numbers of MoS2 layers are removed uniformly across domains with vastly different initial thickness, without affecting the underlying SiO2 substrate and the remaining MoS2 layers. The etching rates can be tuned to achieve complete MoS2 removal and any desired number of MoS2 layers including monolayer. Layer-dependent vibrational and photoluminescence spectra of the etched MoS2 are also demonstrated. This soft plasma etching technique is versatile, scalable, compatible with the semiconductor manufacturing processes, and may be applicable for a broader range of 2D materials and intended device applications. PMID:26813335

Method of inducing differential etch rates in glow discharge produced amorphous silicon

DOEpatents

Staebler, David L.; Zanzucchi, Peter J.

1980-01-01

A method of inducing differential etch rates in glow discharge produced amorphous silicon by heating a portion of the glow discharge produced amorphous silicon to a temperature of about 365.degree. C. higher than the deposition temperature prior to etching. The etch rate of the exposed amorphous silicon is less than the unheated amorphous silicon.

Effects of different orthodontic primers on enamel demineralization around orthodontic brackets.

PubMed

Baysal, Asli; Yasa, Asli; Sogut, Ozlem; Ozturk, Mehmet Ali; Uysal, Tancan

2015-09-01

The purpose of this work is to evaluate the effectiveness of one self-etching and two filled orthodontic primers on enamel demineralization around orthodontic brackets. Brackets were bonded to 84 bovine teeth and the vestibular enamel surfaces covered with acid-resistant nail varnish exposing 1 mm of space on each side of the bracket base. The teeth were allocated to four groups, using either Transbond XT conventional primer on etched enamel (group 1), Transbond Plus Self-Etching Primer on untreated enamel (group 2), Pro Seal filled resin primer on etched enamel (group 3), or Opal Seal filled resin primer on etched enamel (group 4). Each tooth was subjected to 15,000 strokes of brushing followed by exposure to an acid challenge. Calcium-ion release from each sample was calculated using atomic absorption spectrophotometry. Data were analyzed using one-way ANOVA and a post hoc Tukey test. Differences were considered statistically significant at p ≤ 0.05. Statistically significant differences were observed between the four groups (p < 0.001). No significant difference was found between the controls (group 1) and the Opal Seal group. Higher calcium release was observed in the Pro Seal group and the self-etching primer group compared to the controls. The highest calcium release was recorded in the self-etching primer group. Filled sealants may not have a protective effect against enamel demineralization. Transbond Plus Self-Etching Primer should be used cautiously, considering the risk of demineralization involved in its application.

Monoenergetic source of kilodalton ions from Taylor cones of ionic liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larriba, C.; Castro, S.; Fernandez de la Mora, J.

2007-04-15

The ionic liquid ion sources (ILISs) recently introduced by Lozano and Martinez Sanchez [J. Colloid Interface Sci. 282, 415 (2005)], based on electrochemically etched tungsten tips as emitters for Taylor cones of ionic liquids (ILs), have been tested with ionic liquids [A{sup +}B{sup -}] of increasing molecular weight and viscosity. These ILs have electrical conductivities well below 1 S/m and were previously thought to be unsuitable to operate in the purely ionic regime because their Taylor cones produce mostly charged drops from conventional capillary tube sources. Strikingly, all the ILs tried on ILIS form charged beams composed exclusively of smallmore » ions and cluster ions A{sup +}(AB){sub n} or B{sup -}(AB){sub n}, with abundances generally peaking at n=1. Particularly interesting are the positive and negative ion beams produced from the room temperature molten salts 1-methyl-3-pentylimidazolium tris(pentafluoroethyl) trifluorophosphate (C{sub 5}MI-(C{sub 2}F{sub 5}){sub 3}PF{sub 3}) and 1-ethyl-3-methylimidazolium bis(pentafluoroethyl) sulfonylimide (EMI-(C{sub 2}F{sub 5}SO{sub 3}){sub 2}N). We extend to these heavier species the previous conclusions from Lozano and Martinez Sanchez on the narrow energy distributions of the ion beams. In combination with suitable ILs, this source yields nanoamphere currents of positive and negative monoenergetic molecular ions with masses exceeding 2000 amu. Potential applications are in biological secondary ion mass spectrometry, chemically assisted high-resolution ion beam etching, and electrical propulsion. Advantages of the ILISs versus similar liquid metal ion sources include the possibility to form negative as well as positive ion beams and a much wider range of ion compositions and molecular masses.« less

High-density plasma etching of III-nitrides: Process development, device applications and damage remediation

NASA Astrophysics Data System (ADS)

Singh, Rajwinder

Plasma-assisted etching is a key technology for III-nitride device fabrication. The inevitable etch damage resulting from energetic pattern transfer is a challenge that needs to be addressed in order to optimize device performance and reliability. This dissertation focuses on the development of a high-density inductively-coupled plasma (ICP) etch process for III-nitrides, the demonstration of its applicability to practical device fabrication using a custom built ICP reactor, and development of techniques for remediation of etch damage. A chlorine-based standard dry etch process has been developed and utilized in fabrication of a number of electronic and optoelectronic III-nitride devices. Annealing studies carried out at 700°C have yielded the important insight that the annealing time necessary for making good-quality metal contacts to etch processed n-GaN is very short (<30 sec), comparable with the annealing times necessary for dopant activation of p-GaN films and provides an opportunity for streamlining process flow. Plasma etching degrades contact quality on n-GaN films and this degradation has been found to increase with the rf bias levels (ion energies) used, most notably in films with higher doping levels. Immersion in 1:1 mixture of hydrochloric acid and de-ionized water, prior to metallization, removes some of the etch damage and is helpful in recovering contact quality. In-situ treatment consisting of a slow ramp-down of rf bias at the end of the etch is found to achieve the same effect as the ex-situ treatment. This insitu technique is significantly advantageous in a large-scale production environment because it eliminates a process step, particularly one involving treatment in hydrochloric acid. ICP equipment customization for scaling up the process to full 2-inch wafer size is described. Results on etching of state of the art 256 x 256 AlGaN focal plane arrays of ultraviolet photodetectors are reported, with excellent etch uniformity over the wafer area.

Normally-off AlGaN/GaN-based MOS-HEMT with self-terminating TMAH wet recess etching

NASA Astrophysics Data System (ADS)

Son, Dong-Hyeok; Jo, Young-Woo; Won, Chul-Ho; Lee, Jun-Hyeok; Seo, Jae Hwa; Lee, Sang-Heung; Lim, Jong-Won; Kim, Ji Heon; Kang, In Man; Cristoloveanu, Sorin; Lee, Jung-Hee

2018-03-01

Normally-off AlGaN/GaN-based MOS-HEMT has been fabricated by utilizing damage-free self-terminating tetramethyl ammonium hydroxide (TMAH) recess etching. The device exhibited a threshold voltage of +2.0 V with good uniformity, extremely small hysteresis of ∼20 mV, and maximum drain current of 210 mA/mm. The device also exhibited excellent off-state performances, such as breakdown voltage of ∼800 V with off-state leakage current as low as ∼10-12 A and high on/off current ratio (Ion/Ioff) of 1010. These excellent device performances are believed to be due to the high quality recessed surface, provided by the simple self-terminating TMAH etching.

Effects of dry etching processes on exciton and polariton characteristics in ZnTe

NASA Astrophysics Data System (ADS)

Sun, J. H.; Xie, W. B.; Shen, W. Z.; Ogawa, H.; Guo, Q. X.

2003-12-01

We have employed temperature-dependent reflection spectra to study the effects of reactive ion etching (RIE) on the exciton and polariton characteristics in ZnTe crystals exposed to CH4/H2 gases under different rf plasma powers. Classic exciton-polariton theory has been used to calculate the reflection spectra. By comparing with an as-grown ZnTe crystal and the temperature-dependent behavior, we are able to identify the excitons and RIE-induced polariton structures in these dry etched ZnTe crystals. An increase of the rf plasma power will lead to an increase of defect density in the surface damage layers, resulting in a decrease of the photon energies of the observed exciton and polariton structures.

Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO2.

PubMed

Gasvoda, Ryan J; van de Steeg, Alex W; Bhowmick, Ranadeep; Hudson, Eric A; Agarwal, Sumit

2017-09-13

Surface phenomena during atomic layer etching (ALE) of SiO 2 were studied during sequential half-cycles of plasma-assisted fluorocarbon (CF x ) film deposition and Ar plasma activation of the CF x film using in situ surface infrared spectroscopy and ellipsometry. Infrared spectra of the surface after the CF x deposition half-cycle from a C 4 F 8 /Ar plasma show that an atomically thin mixing layer is formed between the deposited CF x layer and the underlying SiO 2 film. Etching during the Ar plasma cycle is activated by Ar + bombardment of the CF x layer, which results in the simultaneous removal of surface CF x and the underlying SiO 2 film. The interfacial mixing layer in ALE is atomically thin due to the low ion energy during CF x deposition, which combined with an ultrathin CF x layer ensures an etch rate of a few monolayers per cycle. In situ ellipsometry shows that for a ∼4 Å thick CF x film, ∼3-4 Å of SiO 2 was etched per cycle. However, during the Ar plasma half-cycle, etching proceeds beyond complete removal of the surface CF x layer as F-containing radicals are slowly released into the plasma from the reactor walls. Buildup of CF x on reactor walls leads to a gradual increase in the etch per cycle.

Computer program TRACK_TEST for calculating parameters and plotting profiles for etch pits in nuclear track materials

NASA Astrophysics Data System (ADS)

Nikezic, D.; Yu, K. N.

2006-01-01

A computer program called TRACK_TEST for calculating parameters (lengths of the major and minor axes) and plotting profiles in nuclear track materials resulted from light-ion irradiation and subsequent chemical etching is described. The programming steps are outlined, including calculations of alpha-particle ranges, determination of the distance along the particle trajectory penetrated by the chemical etchant, calculations of track coordinates, determination of the lengths of the major and minor axes and determination of the contour of the track opening. Descriptions of the program are given, including the built-in V functions for the two commonly employed nuclear track materials commercially known as LR 115 (cellulose nitrate) and CR-39 (poly allyl diglycol carbonate) irradiated by alpha particles. Program summaryTitle of the program:TRACK_TEST Catalogue identifier:ADWT Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWT Computer:Pentium PC Operating systems:Windows 95+ Programming language:Fortran 90 Memory required to execute with typical data:256 MB No. of lines in distributed program, including test data, etc.: 2739 No. of bytes in distributed program, including test data, etc.:204 526 Distribution format:tar.gz External subprograms used:The entire code must be linked with the MSFLIB library Nature of problem: Fast heavy charged particles (like alpha particles and other light ions etc.) create latent tracks in some dielectric materials. After chemical etching in aqueous NaOH or KOH solutions, these tracks become visible under an optical microscope. The growth of a track is based on the simultaneous actions of the etchant on undamaged regions (with the bulk etch rate V) and along the particle track (with the track etch rate V). Growth of the track is described satisfactorily by these two parameters ( V and V). Several models have been presented in the past describing the track development, one of which is the model of Nikezic and Yu (2003) [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45] used in the present program. The present computer program has been written to calculate coordinates of points on the track wall and to determine other relevant track parameters. Solution method:Coordinates of points on the track wall assuming normal incidence were calculated by using the method as described by Fromm et al. (1988) [M. Fromm, A. Chambaudet, F. Membrey, Data bank for alpha particle tracks in CR39 with energies ranging from 0.5 to 5 MeV recording for various incident angles, Nucl. Tracks Radiat. Meas. 15 (1988) 115-118]. The track is then rotated through the incident angle in order to obtain the coordinates of the oblique track [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45; D. Nikezic, Three dimensional analytical determination of the track parameters, Radiat. Meas. 32 (2000) 277-282]. In this way, the track profile in two dimensions (2D) was obtained. In the next step, points in the track wall profile are rotated around the particle trajectory. In this way, circles that outline the track in three dimensions (3D) are obtained. The intersection between the post-etching surface of the detector and the 3D track is the track opening (or the track contour). Coordinates of the track 2D and 3D profiles and the track opening are saved in separate output data files. Restrictions: The program cannot calculate track parameters for the incident angle of exactly 90°. The alpha-particle energy should be smaller than 10 MeV. Furthermore, the program cannot perform calculations for tracks in some extreme cases, such as for very low incident energies or very small incident angles. Additional comments: This is a freeware, but publications arising from using this program should cite the present paper and the paper describing the track growth model [D. Nikezic, K.N. Yu, Three-dimensional analytical determination of the track parameters. Over-etched tracks, Radiat. Meas. 37 (2003) 39-45]. Moreover, the references for the V functions used should also be cited. For the CR-39 detector: Function (1): S.A. Durrani, R.K. Bull, Solid State Nuclear Track Detection. Principles, Methods and Applications, Pergamon Press, 1987. Function (2): C. Brun, M. Fromm, M. Jouffroy, P. Meyer, J.E. Groetz, F. Abel, A. Chambaudet, B. Dorschel, D. Hermsdorf, R. Bretschneider, K. Kadner, H. Kuhne, Intercomparative study of the detection characteristics of the CR-39 SSNTD for light ions: Present status of the Besancon-Dresden approaches, Radiat. Meas. 31 (1999) 89-98. Function (3): K.N. Yu, F.M.F. Ng, D. Nikezic, Measuring depths of sub-micron tracks in a CR-39 detector from replicas using atomic force microscopy, Radiat. Meas. 40 (2005) 380-383. For the LR 115 detector: Function (1): S.A. Durrani, P.F. Green, The effect of etching conditions on the response of LR 115, Nucl. Tracks 8 (1984) 21-24. Function (2): C.W.Y. Yip, D. Nikezic, J.P.Y Ho, K.N. Yu, Chemical etching characteristics for cellulose nitrate, Mat. Chem. Phys. 95 (2005) 307-312. Running time: Order of several minutes, dependent on input parameters and the resolution requested by the user.

Micro knife-edge optical measurement device in a silicon-on-insulator substrate.

PubMed

Chiu, Yi; Pan, Jiun-Hung

2007-05-14

The knife-edge method is a commonly used technique to characterize the optical profiles of laser beams or focused spots. In this paper, we present a micro knife-edge scanner fabricated in a silicon-on-insulator substrate using the micro-electromechanical-system technology. A photo detector can be fabricated in the device to allow further integration with on-chip signal conditioning circuitry. A novel backside deep reactive ion etching process is proposed to solve the residual stress effect due to the buried oxide layer. Focused optical spot profile measurement is demonstrated.

Fabrication of monolithic microfluidic channels in diamond with ion beam lithography

NASA Astrophysics Data System (ADS)

Picollo, F.; Battiato, A.; Boarino, L.; Ditalia Tchernij, S.; Enrico, E.; Forneris, J.; Gilardino, A.; Jakšić, M.; Sardi, F.; Skukan, N.; Tengattini, A.; Olivero, P.; Re, A.; Vittone, E.

2017-08-01

In the present work, we report on the monolithic fabrication by means of ion beam lithography of hollow micro-channels within a diamond substrate, to be employed for microfluidic applications. The fabrication strategy takes advantage of ion beam induced damage to convert diamond into graphite, which is characterized by a higher reactivity to oxidative etching with respect to the chemically inert pristine structure. This phase transition occurs in sub-superficial layers thanks to the peculiar damage profile of MeV ions, which mostly damage the target material at their end of range. The structures were obtained by irradiating commercial CVD diamond samples with a micrometric collimated C+ ion beam at three different energies (4 MeV, 3.5 MeV and 3 MeV) at a total fluence of 2 × 1016 cm-2. The chosen multiple-energy implantation strategy allows to obtain a thick box-like highly damaged region ranging from 1.6 μm to 2.1 μm below the sample surface. High-temperature annealing was performed to both promote the graphitization of the ion-induced amorphous layer and to recover the pristine crystalline structure in the cap layer. Finally, the graphite was removed by ozone etching, obtaining monolithic microfluidic structures. These prototypal microfluidic devices were tested injecting aqueous solutions and the evidence of the passage of fluids through the channels was confirmed by confocal fluorescent microscopy.

High throughput on-chip analysis of high-energy charged particle tracks using lensfree imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Wei; Shabbir, Faizan; Gong, Chao

2015-04-13

We demonstrate a high-throughput charged particle analysis platform, which is based on lensfree on-chip microscopy for rapid ion track analysis using allyl diglycol carbonate, i.e., CR-39 plastic polymer as the sensing medium. By adopting a wide-area opto-electronic image sensor together with a source-shifting based pixel super-resolution technique, a large CR-39 sample volume (i.e., 4 cm × 4 cm × 0.1 cm) can be imaged in less than 1 min using a compact lensfree on-chip microscope, which detects partially coherent in-line holograms of the ion tracks recorded within the CR-39 detector. After the image capture, using highly parallelized reconstruction and ion track analysis algorithms running on graphics processingmore » units, we reconstruct and analyze the entire volume of a CR-39 detector within ∼1.5 min. This significant reduction in the entire imaging and ion track analysis time not only increases our throughput but also allows us to perform time-resolved analysis of the etching process to monitor and optimize the growth of ion tracks during etching. This computational lensfree imaging platform can provide a much higher throughput and more cost-effective alternative to traditional lens-based scanning optical microscopes for ion track analysis using CR-39 and other passive high energy particle detectors.« less

Interaction of boron cluster ions with water: Single collision dynamics and sequential etching

NASA Astrophysics Data System (ADS)

Hintz, Paul A.; Ruatta, Stephen A.; Anderson, Scott L.

1990-01-01

Reactions of mass-selected, cooled, boron cluster ions (B+n, n=1-14) with water have been studied for collision energies from 0.1 to 6.0 eV. Most work was done with D2O, however isotope effects were examined for selected reactant cluster ions. For all size clusters there are exoergic product channels, which in most cases have no activation barriers. Cross sections are generally large, however there are fluctuations with cluster size in total reactivity, collision energy dependences, and in product distributions. For small cluster ions, there is a multitude of product channels. For clusters larger than B+6, the product distributions are dominated by a single channel: Bn-1D++DBO. Under multiple collision conditions, the primary products undergo a remarkable sequence of secondary ``etching'' reactions. As these occur, boron atoms are continuously replaced by hydrogen, and the intermediate products retain the composition: Bn-mH+m. This highly efficient chemistry appears to continue unchanged as the composition changes from pure boron to mostly hydrogen. Comparison of these results is made with boron cluster ion reactions with O2 and D2, as well as reactions with water of aluminum and silicon cluster ions. Some discussion is given of the thermochemistry for these reactions, and a possible problem with the thermochemical data in the BOD/DBO system is discussed.

Composition/bandgap selective dry photochemical etching of semiconductor materials

DOEpatents

Ashby, C.I.H.; Dishman, J.L.

1985-10-11

Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

Effective formation method for an aspherical microlens array based on an aperiodic moving mask during exposure.

PubMed

Shi, Lifang; Du, Chunlei; Dong, Xiaochun; Deng, Qiling; Luo, Xiangang

2007-12-01

An aperiodic mask design method for fabricating a microlens array with an aspherical profile is proposed. The nonlinear relationship between exposure doses and lens profile is considered, and the select criteria of quantization interval and fabrication range of the method are given. The mask function of a quadrangle microlens array with a hyperboloid profile used in the infrared was constructed by using this method. The microlens array can be effectively fabricated during a one time exposure process using the mask. Reactive ion etching was carried out to transfer the structure into the substrate of germanium. The measurement results indicate that the roughness is less than 10 nm (pv), and the profile error is less than 40 nm (rms).

Effect of ribbon width on electrical transport properties of graphene nanoribbons

NASA Astrophysics Data System (ADS)

Bang, Kyuhyun; Chee, Sang-Soo; Kim, Kangmi; Son, Myungwoo; Jang, Hanbyeol; Lee, Byoung Hun; Baik, Kwang Hyeon; Myoung, Jae-Min; Ham, Moon-Ho

2018-03-01

There has been growing interest in developing nanoelectronic devices based on graphene because of its superior electrical properties. In particular, patterning graphene into a nanoribbon can open a bandgap that can be tuned by changing the ribbon width, imparting semiconducting properties. In this study, we report the effect of ribbon width on electrical transport properties of graphene nanoribbons (GNRs). Monolayer graphene sheets and Si nanowires (NWs) were prepared by chemical vapor deposition and a combination of nanosphere lithography and metal-assisted electroless etching from a Si wafer, respectively. Back-gated GNR field-effect transistors were fabricated on a heavily p-doped Si substrate coated with a 300 nm-thick SiO2 layer, by O2 reactive ion etching of graphene sheets using etch masks based on Si NWs aligned on the graphene between the two electrodes by a dielectrophoresis method. This resulted in GNRs with various widths in a highly controllable manner, where the on/off current ratio was inversely proportional to ribbon width. The field-effect mobility decreased with decreasing GNR widths due to carrier scattering at the GNR edges. These results demonstrate the formation of a bandgap in GNRs due to enhanced carrier confinement in the transverse direction and edge effects when the GNR width is reduced.

Advanced fabrication of Si nanowire FET structures by means of a parallel approach.

PubMed

Li, J; Pud, S; Mayer, D; Vitusevich, S

2014-07-11

In this paper we present fabricated Si nanowires (NWs) of different dimensions with enhanced electrical characteristics. The parallel fabrication process is based on nanoimprint lithography using high-quality molds, which facilitates the realization of 50 nm-wide NW field-effect transistors (FETs). The imprint molds were fabricated by using a wet chemical anisotropic etching process. The wet chemical etch results in well-defined vertical sidewalls with edge roughness (3σ) as small as 2 nm, which is about four times better compared with the roughness usually obtained for reactive-ion etching molds. The quality of the mold was studied using atomic force microscopy and scanning electron microscopy image data. The use of the high-quality mold leads to almost 100% yield during fabrication of Si NW FETs as well as to an exceptional quality of the surfaces of the devices produced. To characterize the Si NW FETs, we used noise spectroscopy as a powerful method for evaluating device performance and the reliability of structures with nanoscale dimensions. The Hooge parameter of fabricated FET structures exhibits an average value of 1.6 × 10(-3). This value reflects the high quality of Si NW FETs fabricated by means of a parallel approach that uses a nanoimprint mold and cost-efficient technology.

A Sliding-Mode Triboelectric Nanogenerator with Chemical Group Grated Structure by Shadow Mask Reactive Ion Etching.

PubMed

Shang, Wanyu; Gu, Guang Qin; Yang, Feng; Zhao, Lei; Cheng, Gang; Du, Zu-Liang; Wang, Zhong Lin

2017-09-26

The sliding-mode triboelectric nanogenerator (S-TENG) with grated structure has important applications in energy harvest and active sensors; however its concavo-convex structure leads to large frictional resistance and abrasion. Here, we developed a S-TENG with a chemical group grated structure (S-TENG-CGG), in which the triboelectric layer's triboelectric potential has a positive-negative alternating charged structure. The triboelectric layer of the S-TENG-CGG was fabricated through a reactive ion etching process with a metal shadow mask with grated structure. In the etched region, the nylon film, originally positively charged as in friction with stainless steel, gained opposite triboelectric potential and became negatively charged because of the change of surface functional groups. The output signals of the S-TENG-CGG are alternating and the frequency is determined by both the segment numbers and the moving speed. The applications of the S-TENG-CGG in the charging capacitor and driving calculator are demonstrated. In the S-TENG-CGG, since there is no concavo-convex structure, the frictional resistance and abrasion are largely reduced, which enhances its performances in better stability and longer working time.

Vertical-cavity surface-emitting lasers - Design, growth, fabrication, characterization

NASA Astrophysics Data System (ADS)

Jewell, Jack L.; Lee, Y. H.; Harbison, J. P.; Scherer, A.; Florez, L. T.

1991-06-01

The authors have designed, fabricated, and tested vertical-cavity surface-emitting lasers (VCSEL) with diameters ranging from 0.5 microns to above 50 microns. Design issues, molecular beam epitaxial growth, fabrication, and lasing characteristics are discussed. The topics considered in fabrication of VCSELs are microlaser geometries; ion implementation and masks; ion beam etching; packaging and arrays; and ultrasmall devices.

CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification.

PubMed

Baccou, C; Yahia, V; Depierreux, S; Neuville, C; Goyon, C; Consoli, F; De Angelis, R; Ducret, J E; Boutoux, G; Rafelski, J; Labaune, C

2015-08-01

Laser-accelerated ion beams can be used in many applications and, especially, to initiate nuclear reactions out of thermal equilibrium. We have experimentally studied aneutronic fusion reactions induced by protons accelerated by the Target Normal Sheath Acceleration mechanism, colliding with a boron target. Such experiments require a rigorous method to identify the reaction products (alpha particles) collected in detectors among a few other ion species such as protons or carbon ions, for example. CR-39 track detectors are widely used because they are mostly sensitive to ions and their efficiency is near 100%. We present a complete calibration of CR-39 track detector for protons, alpha particles, and carbon ions. We give measurements of their track diameters for energy ranging from hundreds of keV to a few MeV and for etching times between 1 and 8 h. We used these results to identify alpha particles in our experiments on proton-boron fusion reactions initiated by laser-accelerated protons. We show that their number clearly increases when the boron fuel is preformed in a plasma state.

CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baccou, C., E-mail: claire.baccou@polytechnique.edu; Yahia, V.; Labaune, C.

Laser-accelerated ion beams can be used in many applications and, especially, to initiate nuclear reactions out of thermal equilibrium. We have experimentally studied aneutronic fusion reactions induced by protons accelerated by the Target Normal Sheath Acceleration mechanism, colliding with a boron target. Such experiments require a rigorous method to identify the reaction products (alpha particles) collected in detectors among a few other ion species such as protons or carbon ions, for example. CR-39 track detectors are widely used because they are mostly sensitive to ions and their efficiency is near 100%. We present a complete calibration of CR-39 track detectormore » for protons, alpha particles, and carbon ions. We give measurements of their track diameters for energy ranging from hundreds of keV to a few MeV and for etching times between 1 and 8 h. We used these results to identify alpha particles in our experiments on proton-boron fusion reactions initiated by laser-accelerated protons. We show that their number clearly increases when the boron fuel is preformed in a plasma state.« less

Reaction of Si nanopowder with water investigated by FT-IR and XPS

NASA Astrophysics Data System (ADS)

Imamura, Kentaro; Kobayashi, Yuki; Matsuda, Shinsuke; Akai, Tomoki; Kobayashi, Hikaru

2017-08-01

The initial reaction of Si nanopowder with water to generate hydrogen is investigated using FT-IR and XPS measurements. Si nanopowder is fabricated using the simple beads milling method. For HF-etched Si nanopowder, strong peaks due to Si-H and Si-H2 stretching vibrational modes and a weak shoulder peak due to Si-H3 are observed. Although no peaks due to oxide is observed in the Si 2p XPS spectrum, weak vibrational peaks due to HSiO2 and HSiO3 species are observable. The hydrogen generation rate greatly increases with pH, indicating that the reacting species is hydroxide ions (OH- ions). After the reaction, the intensities of the peaks due to SiH and SiH2 species decrease while those for HSiO, HSiO2, and HSiO3 species increase. This result demonstrates that OH- ions attack Si back-bonds, with surface Si-H bonds remaining. After initial reaction of HF-etched Si nanopowder with heavy water, vibrational peaks for SiD, SiDH, and SiDH2 appear, and then, a peak due to DSiO3 species is observed, but no peaks due to DSiO2 and DSiO species are observable. This result indicates that SiD, SiDH, and SiDH2 species are formed by substitution reactions, followed by oxidation of back-bonds to form DSiO3 species. After immersion in D2O for a day, 37% H atoms on the surface are replaced to D atoms.

Effect of the chamber wall on fluorocarbon-assisted atomic layer etching of SiO{sub 2} using cyclic Ar/C{sub 4}F{sub 8} plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawakami, Masatoshi; Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu

2016-07-15

The authors studied the effect of the temperature and chemical state of the chamber wall on process performance for atomic layer etching of SiO{sub 2} using a steady-state Ar plasma, periodic injection of a defined number of C{sub 4}F{sub 8} molecules, and synchronized plasma-based Ar{sup +} ion bombardment. To evaluate these effects, the authors measured the quartz coupling window temperature. The plasma gas phase chemistry was characterized using optical emission spectroscopy. It was found that although the thickness of the polymer film deposited in each cycle is constant, the etching behavior changed, which is likely related to a change inmore » the plasma gas phase chemistry. The authors found that the main gas phase changes occur after C{sub 4}F{sub 8} injection. The C{sub 4}F{sub 8} and the quartz window react and generate SiF and CO. The emission intensity changes with wall surface state and temperature. Therefore, changes in the plasma gas species generation can lead to a shift in etching performance during processing. During initial cycles, minimal etching is observed, while etching gradually increases with cycle number.« less

Fabrication, characterization, and potential application of carbon fiber cone nanometer-size electrodes.

PubMed

Zhang, X; Zhang, W; Zhou, X; Ogorevc, B

1996-10-01

A novel method has been developed for the fabrication of carbon fiber cone nanometer-size ultramicroelectrodes (nanoelectrodes) with overall tip dimensions as small as 50 nm in diameter. In this method, carbon fibers were initially etched by an argon ion beam thinner. Afterward, a single etched carbon fiber was inserted into a glass capillary, which was then sealed by heating the glass/fiber interface in a vacuum; thus, no epoxy resin is involved. The success rate of our fabrication route for the electrodes with overall tip diameters of up to 500 nm was about 80%; for those with tip diameters of up to 100 nm, it was about 50%. The fabricated carbon fiber cone nanoelectrodes (CFCNEs) were inspected by optical and scanning electron microscopy. Their electrochemical behavior was examined by cyclic and linear sweep voltammetric measurements of ferricyanide and ferrocene ions in aqueous and nonaqueous media. The potential analytical applicability of the CFCNEs was tested by differential pulse voltammetric measurements of two well-known neurotransmitters, dopamine (DA) and 5-hydroxytryptamine (5-HT), and the results achieved were highly satisfactory. The calibration plots obtained were linear over the ranges from 5.0 × 10(-7) to 1.0 × 10(-4) and from 2.0 × 10(-6) to 1.0 × 10(-4) mol/L, with limits of detection of 1.0 × 10(-7) and 5.0 × 10(-7) mol/L for DA and 5-HT, respectively. Some advantages and improvements of the proposed CFCNE fabrication method, especially with respect to smoothness of the fiber (electrode) surface, strength, and control over the fiber tip dimensions, are also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattox, D.M.; Sharp, D.J.

A Veeco microetch system which uses a Kaufman type ion source has been used to study ion erosion yields for a variety of materials of possible interest in CTR wall coating applications. A schematic diagram of the Kaufman gun and etching chamber are given. The ion beam is nearly monoenergetic (within several eV). The extracted ion beam consists of a mixture of H/sub 2//sup +/ and H/sup +/. A H/sub 2//sup +/ ion will have a sputtering yield equivalent to 2H/sup +/ ions with one-half the energy of the H/sub 2//sup +/ ion. For most of these investigations, the chargemore » compensation filament is removed to avoid sputtering of the tungsten filament.« less

Wafer edge overlay control solution for N7 and beyond

NASA Astrophysics Data System (ADS)

van Haren, Richard; Calado, Victor; van Dijk, Leon; Hermans, Jan; Kumar, Kaushik; Yamashita, Fumiko

2018-03-01

Historically, the on-product overlay performance close to the wafer edge is lagging with respect to the inner part of the wafer. The reason for this is that wafer processing is less controlled close to the wafer edge as opposed to the rest of the wafer. It is generally accepted that Chemical Vapor Deposition (CVD) of stressed layers that cause wafer warp, wafer table contamination, Chemical Mechanical Polishing (CMP), and Reactive Ion Etch (RIE) may deteriorate the overlay performance and/or registration close to the wafer edge. For the N7 technology node and beyond, it is anticipated that the tight on-product overlay specification is required across the full wafer which includes the edge region. In this work, we highlight one contributor that may negatively impact the on-product overlay performance, namely the etch step. The focus will be mainly on the wafer edge region but the remaining part of the wafer is considered as well. Three use-cases are examined: multiple Litho-Etch steps (LEn), contact hole layer etch, and the copper dual damascene etch. We characterize the etch contribution by considering the overlay measurement after resist development inspect (ADI) and after etch inspect (AEI). We show that the Yieldstar diffraction based overlay (μDBO) measurements can be utilized to characterize the etch contribution to the overlay budget. The effects of target asymmetry as well as overlay shifts are considered and compared with SEM measurements. Based on the results above, we propose a control solution aiming to reduce or even eliminate the delta between ADI and AEI. By doing so, target/mark to device offsets due to etch might be avoided.

Fabrication of planarised conductively patterned diamond for bio-applications.

PubMed

Tong, Wei; Fox, Kate; Ganesan, Kumaravelu; Turnley, Ann M; Shimoni, Olga; Tran, Phong A; Lohrmann, Alexander; McFarlane, Thomas; Ahnood, Arman; Garrett, David J; Meffin, Hamish; O'Brien-Simpson, Neil M; Reynolds, Eric C; Prawer, Steven

2014-10-01

The development of smooth, featureless surfaces for biomedical microelectronics is a challenging feat. Other than the traditional electronic materials like silicon, few microelectronic circuits can be produced with conductive features without compromising the surface topography and/or biocompatibility. Diamond is fast becoming a highly sought after biomaterial for electrical stimulation, however, its inherent surface roughness introduced by the growth process limits its applications in electronic circuitry. In this study, we introduce a fabrication method for developing conductive features in an insulating diamond substrate whilst maintaining a planar topography. Using a combination of microwave plasma enhanced chemical vapour deposition, inductively coupled plasma reactive ion etching, secondary diamond growth and silicon wet-etching, we have produced a patterned substrate in which the surface roughness at the interface between the conducting and insulating diamond is approximately 3 nm. We also show that the patterned smooth topography is capable of neuronal cell adhesion and growth whilst restricting bacterial adhesion. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth process for gallium nitride porous nanorods

DOEpatents

Wildeson, Isaac Harshman; Sands, Timothy David

2015-03-24

A GaN nanorod and formation method. Formation includes providing a substrate having a GaN film, depositing SiN.sub.x on the GaN film, etching a growth opening through the SiN.sub.x and into the GaN film, growing a GaN nanorod through the growth opening, the nanorod having a nanopore running substantially through its centerline. Focused ion beam etching can be used. The growing can be done using organometallic vapor phase epitaxy. The nanopore diameter can be controlled using the growth opening diameter or the growing step duration. The GaN nanorods can be removed from the substrate. The SiN.sub.x layer can be removed after the growing step. A SiO.sub.x template can be formed on the GaN film and the GaN can be grown to cover the SiO.sub.x template before depositing SiN.sub.x on the GaN film. The SiO.sub.x template can be removed after growing the nanorods.

Improvement in lifetime of green organic light-emitting device

NASA Astrophysics Data System (ADS)

Ki, Hyun Chul; Kim, Seon Hoon; Kim, Doo Gun; Kim, Hyun Jin; Ko, Hang Ju; Han, Myung-Soo; Kim, Hwe Jong; Hong, Kyung Jin

2010-02-01

We have proposed a novel encapsulation method with simple process in comparison with conventional encapsulation technique. Here, the encapsulation film of silicon dioxide is steady for external environment because this can be designed to cover the emitting organic material from air. Silicon dioxide of 220 nm was deposited by plasma enhanced chemical vapor deposition and etched by reactive ion etching system. Then, Alq3 was used as a material to emitting layer in the green (organic light emitting device) OLED and TPD in the hole transportation layer was used for the harmonious transportation of hole. Luminance was measured with 40 hour intervals at the air-exposed condition. After 400, 1,000, 1,600, and 2,000 hours, luminance of green OLED were 7,366, 7,200, 6,210, and 5,100 cd/m2, respectively. Luminance of green OLED doesn't decrease until 2,000 hours. As a results, proposed encapsulation technique can increase the life time of green OLED.

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.

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.

A molded surface-micromachining and bulk etching release (MOSBE) fabrication platform on (1 1 1) Si for MOEMS

NASA Astrophysics Data System (ADS)

Wu, Mingching; Fang, Weileun

2006-02-01

This work attempts to integrate poly-Si thin film and single-crystal-silicon (SCS) structures in a monolithic process. The process integrated multi-depth DRIE (deep reactive ion etching), trench-refilled molding, a two poly-Si MUMPs process and (1 1 1) Si bulk micromachining to accomplish multi-thickness and multi-depth structures for superior micro-optical devices. In application, a SCS scanning mirror driven by self-aligned vertical comb-drive actuators was demonstrated. The stiffness of the mirror was significantly increased by thick SCS structures. The thin poly-Si film served as flexible torsional springs and electrical routings. The depth difference of the vertical comb electrodes was tuned by DRIE to increase the devices' stroke. Finally, a large moving space was available after the bulk Si etching. In summary, the present fabrication process, named (1 1 1) MOSBE (molded surface-micromachining and bulk etching release on (1 1 1) Si substrate), can further integrate with the MUMPs devices to establish a more powerful platform.

Lithography-free glass surface modification by self-masking during dry etching

NASA Astrophysics Data System (ADS)

Hein, Eric; Fox, Dennis; Fouckhardt, Henning

2011-01-01

Glass surface morphologies with defined shapes and roughness are realized by a two-step lithography-free process: deposition of an ~10-nm-thin lithographically unstructured metallic layer onto the surface and reactive ion etching in an Ar/CF4 high-density plasma. Because of nucleation or coalescence, the metallic layer is laterally structured during its deposition. Its morphology exhibits islands with dimensions of several tens of nanometers. These metal spots cause a locally varying etch velocity of the glass substrate, which results in surface structuring. The glass surface gets increasingly rougher with further etching. The mechanism of self-masking results in the formation of surface structures with typical heights and lateral dimensions of several hundred nanometers. Several metals, such as Ag, Al, Au, Cu, In, and Ni, can be employed as the sacrificial layer in this technology. Choice of the process parameters allows for a multitude of different glass roughness morphologies with individual defined and dosed optical scattering.

Enhanced field electron emission from aligned diamond-like carbon nanorod arrays prepared by reactive ion beam etching

NASA Astrophysics Data System (ADS)

Zhao, Yong; Qin, Shi-Qiao; Zhang, Xue-Ao; Chang, Sheng-Li; Li, Hui-Hui; Yuan, Ji-Ren

2016-05-01

Homogeneous diamond-like carbon (DLC) films were deposited on Si supports by a pulsed filtered cathodic vacuum arc deposition system. Using DLC films masked by Ni nanoparticles as precursors, highly aligned diamond-like carbon nanorod (DLCNR) arrays were fabricated by the etching of inductively coupled radio frequency oxygen plasma. The as-prepared DLCNR arrays exhibit excellent field emission properties with a low turn-on field of 2.005 V μm-1 and a threshold field of 4.312 V μm-1, respectively. Raman spectroscopy and x-ray photoelectron spectroscopy were employed to determine the chemical bonding structural change of DLC films before and after etching. It is confirmed that DLC films have good connection with Si supports via the formation of the SiC phase, and larger conductive sp2 domains are formed in the as-etched DLC films, which play essential roles in the enhanced field emission properties for DLCNR arrays.

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.

Effect of Etching Methods in Metallographic Studies of Duplex Stainless Steel 2205

NASA Astrophysics Data System (ADS)

Kisasoz, A.; Karaaslan, A.; Bayrak, Y.

2017-03-01

Three different etching methods are used to uncover the ferrite-austenite structure and precipitates of secondary phases in stainless steel 22.5% Cr - 5.4% Ni - 3% Mo - 1.3% Mn. The structure is studied under a light microscope. The chemical etching is conducted in a glycerol solution of HNO3, HCl and HF; the electrochemical etching is conducted in solutions of KOH and NaOH.

Three-dimensional collimation of in-plane-propagating light using silicon micromachined mirror

NASA Astrophysics Data System (ADS)

Sabry, Yasser M.; Khalil, Diaa; Saadany, Bassam; Bourouina, Tarik

2014-03-01

We demonstrate light collimation of single-mode optical fibers using deeply-etched three-dimensional curved micromirror on silicon chip. The three-dimensional curvature of the mirror is controlled by a process combining deep reactive ion etching and isotropic etching of silicon. The produced surface is astigmatic with out-of-plane radius of curvature that is about one half the in-plane radius of curvature. Having a 300-μm in-plane radius and incident beam inplane inclined with an angle of 45 degrees with respect to the principal axis, the reflected beam is maintained stigmatic with about 4.25 times reduction in the beam expansion angle in free space and about 12-dB reduction in propagation losses, when received by a limited-aperture detector.

Experimental visualization of the cathode layer in AC surface dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Kim, Sang-You; Lho, Taihyeop; Chung, Kyu-Sun

2018-06-01

A narrow etched polyimide line at the bottom edge of a biased electrode (BE) and a non-etched dielectric surface near the biased electrode were observed in an atmospheric AC flexible surface dielectric barrier discharge of polyimide dielectric. These findings are attributed to the bombardment of positive oxygen ions on the bottom edge of the BE and the electron breakdown trajectory not contacting the polyimide surface following the electric field lines formed between the BE edge and the surface charge layer on the dielectric. The length of the non-etched dielectric surface during the first micro-discharge was observed as 22 μm. This occurred, regardless of three different operating durations, which is in good agreement with the length of the cathode layer according to Paschen's law.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kan, Jimmy J.; Gottwald, Matthias; Fullerton, Eric E.

We describe low-temperature characterization of magnetic tunnel junctions (MTJs) patterned by reactive ion etching for spin-transfer-torque magnetic random access memory. Magnetotransport measurements of typical MTJs show increasing tunneling magnetoresistance (TMR) and larger coercive fields as temperature is decreased down to 10 K. However, MTJs selected from the high-resistance population of an MTJ array exhibit stable intermediate magnetic states when measured at low temperature and show TMR roll-off below 100 K. These non-ideal low-temperature behaviors arise from edge damage during the etch process and can have negative impacts on thermal stability of the MTJs.

A lithium niobate electro-optic tunable Bragg filter fabricated by electron beam lithography

NASA Astrophysics Data System (ADS)

Pierno, L.; Dispenza, M.; Secchi, A.; Fiorello, A.; Foglietti, V.

2008-06-01

We have designed and fabricated a lithium niobate tunable Bragg filter patterned by electron beam lithography and etched by reactive ion etching. Devices with 1 mm, 2 mm and 4 mm length and 360 and 1080 nm Bragg period, with 5 pm V-1 tuning efficiency, have been characterized. Some applications were identified. Optical simulation based on finite element model (FEM) software showing the optical filtering curve and the coupling factor dependence on the manufacturing parameter is reported. The tuning of the filter window position is electro-optically controlled.

Fluorine-Based DRIE of Fused Silica

NASA Technical Reports Server (NTRS)

Yee, Karl; Shcheglov, Kirill; Li, Jian; Choi, Daniel

2007-01-01

A process of deep reactive-ion etching (DRIE) using a fluorine-based gas mixture enhanced by induction-coupled plasma (ICP) has been demonstrated to be effective in forming high-aspect-ratio three-dimensional patterns in fused silica. The patterns are defined in part by an etch mask in the form of a thick, high-quality aluminum film. The process was developed to satisfy a need to fabricate high-aspect-ratio fused-silica resonators for vibratory microgyroscopes, and could be used to satisfy similar requirements for fabricating other fused-silica components.

A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

NASA Astrophysics Data System (ADS)

Qiu, X.; Cherief, W.; Colombet, D.; Ayela, F.

2017-04-01

We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops.

Maskless micro/nanofabrication on GaAs surface by friction-induced selective etching

PubMed Central

2014-01-01

In the present study, a friction-induced selective etching method was developed to produce nanostructures on GaAs surface. Without any resist mask, the nanofabrication can be achieved by scratching and post-etching in sulfuric acid solution. The effects of the applied normal load and etching period on the formation of the nanostructure were studied. Results showed that the height of the nanostructure increased with the normal load or the etching period. XPS and Raman detection demonstrated that residual compressive stress and lattice densification were probably the main reason for selective etching, which eventually led to the protrusive nanostructures from the scratched area on the GaAs surface. Through a homemade multi-probe instrument, the capability of this fabrication method was demonstrated by producing various nanostructures on the GaAs surface, such as linear array, intersecting parallel, surface mesas, and special letters. In summary, the proposed method provided a straightforward and more maneuverable micro/nanofabrication method on the GaAs surface. PMID:24495647

Fabrication of 3D surface structures using grayscale lithography

NASA Astrophysics Data System (ADS)

Stilson, Christopher; Pal, Rajan; Coutu, Ronald A.

2014-03-01

The ability to design and develop 3D microstructures is important for microelectromechanical systems (MEMS) fabrication. Previous techniques used to create 3D devices included tedious steps in direct writing and aligning patterns onto a substrate followed by multiple photolithography steps using expensive, customized equipment. Additionally, these techniques restricted batch processing and placed limits on achievable shapes. Gray-scale lithography enables the fabrication of a variety of shapes using a single photolithography step followed by reactive ion etching (RIE). Micromachining 3D silicon structures for MEMS can be accomplished using gray-scale lithography along with dry anisotropic etching. In this study, we investigated: using MATLAB for mask designs; feasibility of using 1 μm Heidelberg mask maker to direct write patterns onto photoresist; using RIE processing to etch patterns into a silicon substrate; and the ability to tailor etch selectivity for precise fabrication. To determine etch rates and to obtain desired etch selectivity, parameters such as gas mixture, gas flow, and electrode power were studied. This process successfully demonstrates the ability to use gray-scale lithography and RIE for use in the study of micro-contacts. These results were used to produce a known engineered non-planer surface for testing micro-contacts. Surface structures are between 5 μm and 20 μm wide with varying depths and slopes based on mask design and etch rate selectivity. The engineered surfaces will provide more insight into contact geometries and failure modes of fixed-fixed micro-contacts.

A Dry-Etch Process for Low Temperature Superconducting Transition Edge Sensors for Far Infrared Bolometer Arrays

NASA Technical Reports Server (NTRS)

Allen, Christine A.; Chervenak, James A.; Hsieh, Wen-Ting; McClanahan, Richard A.; Miller, Timothy M.; Mitchell, Robert; Moseley, S. Harvey; Staguhn, Johannes; Stevenson, Thomas R.

2003-01-01

The next generation of ultra-low power bolometer arrays, with applications in far infrared imaging, spectroscopy and polarimetry, utilizes a superconducting bilayer as the sensing element to enable SQUID multiplexed readout. Superconducting transition edge sensors (TES s) are being produced with dual metal systems of superconductinghormal bilayers. The transition temperature (Tc) is tuned by altering the relative thickness of the superconductor with respect to the normal layer. We are currently investigating MoAu and MoCu bilayers. We have developed a dry-etching process for MoAu TES s with integrated molybdenum leads, and are working on adapting the process to MoCu. Dry etching has the advantage over wet etching in the MoAu system in that one can achieve a high degree of selectivity, greater than 10, using argon ME, or argon ion milling, for patterning gold on molybdenum. Molybdenum leads are subsequently patterned using fluorine plasma.. The dry-etch technique results in a smooth, featureless TES with sharp sidewalls, no undercutting of the Mo beneath the normal metal, and Mo leads with high critical current. The effects of individual processing parameters on the characteristics of the transition will be reported.

GaN nanowire arrays with nonpolar sidewalls for vertically integrated field-effect transistors

NASA Astrophysics Data System (ADS)

Yu, Feng; Yao, Shengbo; Römer, Friedhard; Witzigmann, Bernd; Schimpke, Tilman; Strassburg, Martin; Bakin, Andrey; Schumacher, Hans Werner; Peiner, Erwin; Suryo Wasisto, Hutomo; Waag, Andreas

2017-03-01

Vertically aligned gallium nitride (GaN) nanowire (NW) arrays have attracted a lot of attention because of their potential for novel devices in the fields of optoelectronics and nanoelectronics. In this work, GaN NW arrays have been designed and fabricated by combining suitable nanomachining processes including dry and wet etching. After inductively coupled plasma dry reactive ion etching, the GaN NWs are subsequently treated in wet chemical etching using AZ400K developer (i.e., with an activation energy of 0.69 ± 0.02 eV and a Cr mask) to form hexagonal and smooth a-plane sidewalls. Etching experiments using potassium hydroxide (KOH) water solution reveal that the sidewall orientation preference depends on etchant concentration. A model concerning surface bonding configuration on crystallography facets has been proposed to understand the anisotropic wet etching mechanism. Finally, NW array-based vertical field-effect transistors with wrap-gated structure have been fabricated. A device composed of 99 NWs exhibits enhancement mode operation with a threshold voltage of 1.5 V, a superior electrostatic control, and a high current output of >10 mA, which prevail potential applications in next-generation power switches and high-temperature digital circuits.

GaN nanowire arrays with nonpolar sidewalls for vertically integrated field-effect transistors.

PubMed

Yu, Feng; Yao, Shengbo; Römer, Friedhard; Witzigmann, Bernd; Schimpke, Tilman; Strassburg, Martin; Bakin, Andrey; Schumacher, Hans Werner; Peiner, Erwin; Wasisto, Hutomo Suryo; Waag, Andreas

2017-03-03

Vertically aligned gallium nitride (GaN) nanowire (NW) arrays have attracted a lot of attention because of their potential for novel devices in the fields of optoelectronics and nanoelectronics. In this work, GaN NW arrays have been designed and fabricated by combining suitable nanomachining processes including dry and wet etching. After inductively coupled plasma dry reactive ion etching, the GaN NWs are subsequently treated in wet chemical etching using AZ400K developer (i.e., with an activation energy of 0.69 ± 0.02 eV and a Cr mask) to form hexagonal and smooth a-plane sidewalls. Etching experiments using potassium hydroxide (KOH) water solution reveal that the sidewall orientation preference depends on etchant concentration. A model concerning surface bonding configuration on crystallography facets has been proposed to understand the anisotropic wet etching mechanism. Finally, NW array-based vertical field-effect transistors with wrap-gated structure have been fabricated. A device composed of 99 NWs exhibits enhancement mode operation with a threshold voltage of 1.5 V, a superior electrostatic control, and a high current output of >10 mA, which prevail potential applications in next-generation power switches and high-temperature digital circuits.

Registration of alpha particles in Makrofol-E nuclear track detectors

NASA Astrophysics Data System (ADS)

Rammah, Y. S.; Abdalla, Ayman M.; Ashraf, O.; Ashry, A. H.

2016-06-01

Fast detection of alpha particles in the range from 1 to 5 MeV in Makrofol-E polycarbonate nuclear track detectors (PCTDs) using a new chemical etchant was investigated. 252Cf and 241Am-thin open sources were used for irradiating Makrofol-E detectors with fission fragments and alpha particles in air at normal pressure and temperature (NPT). A chain of experimental work has been carried out using new etchants to register alpha particle in short time in Makrofol-E polycarbonate detectors. The etching efficiency were exhibited a clear dependence on the amount of methanol in the etching solution and etching time. The optimized chemical condition obtained at this stage of development for 200 μm Makrofol-E detectors are (8 ml of 10 N NaOH + 2 ml CH3OH) etching solutions at 60 °C for 3 h. In this study; it is possible to observe energy detection windows for Makrofol-E detectors according to applied etching duration. Makrofol-E introduced the characteristic Bragg peak, which indicates the advantages of this detector as alpha spectrometer. Consequently, the suggested new etchant can be developed for heavy ions detection and monitoring radon levels and its daughters.

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

Wafer-Scale Hierarchical Nanopillar Arrays Based on Au Masks and Reactive Ion Etching for Effective 3D SERS Substrate.

PubMed

Men, Dandan; Wu, Yingyi; Wang, Chu; Xiang, Junhuai; Yang, Ganlan; Wan, Changjun; Zhang, Honghua

2018-02-04

Two-dimensional (2D) periodic micro/nanostructured arrays as SERS substrates have attracted intense attention due to their excellent uniformity and good stability. In this work, periodic hierarchical SiO₂ nanopillar arrays decorated with Ag nanoparticles (NPs) with clean surface were prepared on a wafer-scale using monolayer Au NP arrays as masks, followed by reactive ion etching (RIE), depositing Ag layer and annealing. For the prepared SiO₂ nanopillar arrays decorated with Ag NPs, the size of Ag NPs was tuned from ca. 24 to 126 nanometers by controlling the deposition thickness of Ag film. Importantly, the SiO₂ nanopillar arrays decorated with Ag NPs could be used as highly sensitive SERS substrate for the detection of 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) due to the high loading of Ag NPs and a very uniform morphology. With a deposition thickness of Ag layer of 30 nm, the SiO₂ nanopillar arrays decorated with Ag NPs exhibited the best sensitive SERS activity. The excellent SERS performance of this substrate is mainly attributed to high-density "hotspots" derived from nanogaps between Ag NPs. Furthermore, this strategy might be extended to synthesize other nanostructured arrays with a large area, which are difficult to be prepared only via conventional wet-chemical or physical methods.

Coupled chemical reactions in dynamic nanometric confinement: VII. Biosensors based on swift heavy ion tracks with membranes

NASA Astrophysics Data System (ADS)

Fink, D.; Muñoz H., G.; Garcia-Arrelano, H.; Alfonta, L.; Vacik, J.; Kiv, A.; Hnatowicz, V.

2017-02-01

In previous papers it was shown that the coupling of the two chemical reactions: {NaOH etchant - PET polymer} and {NaOH etchant - AgNO3 solution} within the dynamic confinement of etched swift heavy ion tracks eventually leads to the formation of tiny Ag2O membranes within these nanopores, thus separating the latter ones into two adjacent segments. It is shown here that the deposition of enzymes in these two segments transforms these structures into biosensors. In our earlier developed sensors with transparent etched ion tracks, we frequently used glucose oxidase as enzyme and glucose as analyte. In these cases, the enzymatic reaction within the tracks leads to a change in the pH value of the confined solution and hence also in the track conductivity, so these structures can be used for biosensing. When applying, for easy comparison, the same enzyme/analyte combination to the segmented sensor arrangement presented here, we find a striking improvement in detection sensitivity which points at a different biosensing mechanism due to intrinsic polarisation effects across the newly inserted membranes.

High-uniformity centimeter-wide Si etching method for MEMS devices with large opening elements

NASA Astrophysics Data System (ADS)

Okamoto, Yuki; Tohyama, Yukiya; Inagaki, Shunsuke; Takiguchi, Mikio; Ono, Tomoki; Lebrasseur, Eric; Mita, Yoshio

2018-04-01

We propose a compensated mesh pattern filling method to achieve highly uniform wafer depth etching (over hundreds of microns) with a large-area opening (over centimeter). The mesh opening diameter is gradually changed between the center and the edge of a large etching area. Using such a design, the etching depth distribution depending on sidewall distance (known as the local loading effect) inversely compensates for the over-centimeter-scale etching depth distribution, known as the global or within-die(chip)-scale loading effect. Only a single DRIE with test structure patterns provides a micro-electromechanical systems (MEMS) designer with the etched depth dependence on the mesh opening size as well as on the distance from the chip edge, and the designer only has to set the opening size so as to obtain a uniform etching depth over the entire chip. This method is useful when process optimization cannot be performed, such as in the cases of using standard conditions for a foundry service and of short turn-around-time prototyping. To demonstrate, a large MEMS mirror that needed over 1 cm2 of backside etching was successfully fabricated using as-is-provided DRIE conditions.

Dopant type and/or concentration selective dry photochemical etching of semiconductor materials

DOEpatents

Ashby, C.R.H.; Dishman, J.L.

1985-10-11

Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions. In a preferred mode, the materials are subjected to a bias voltage which suppresses etching in n- or p-type material but not in p- or n-type material, respectively; or suppresses etching in the more heavily doped of two n-type or two p-type materials.

Study of electron impact inelastic scattering of chlorine molecule (Cl2)

NASA Astrophysics Data System (ADS)

Yadav, Hitesh; Vinodkumar, Minaxi; Limbachiya, Chetan; Vinodkumar, P. C.

2018-02-01

A theoretical study is carried out for electron interactions with the chlorine molecule (Cl2) for incident energies ranging from 0.01 to 5000 eV. This wide range of energy has allowed us to investigate a variety of processes and report data on symmetric excitation energies, dissociative electron attachment (DEA), total excitation cross sections, and ionization cross section (Q ion) along with total inelastic cross sections (Q inel). The present study is important since Cl2 is a prominent gas for plasma etching and its anionic atoms are important in the etching of semiconductor wafers. In order to compute the total inelastic cross sections, we have employed the ab initio R-matrix method (0.01 to 15 eV) together with the spherical complex optical potential method (∼15 to 5000 eV). The R-matrix calculations are performed using a close coupling method, and we have used DEA estimator via Quantemol-N to calculate the DEA fragmentation and cross sections. The present study finds overall good agreement with the available experimental data. Total excitation and inelastic cross sections of e-{{{Cl}}}2 scattering for a wide energy range (0.01 to 5 keV) are reported for the first time, to the best of our knowledge.

Study of the Anatomy of the X-Ray and Neutron Production Scaling Laws in the Plasma Focus.

DTIC Science & Technology

1980-05-15

plasma focus discharge in deuterium as an extension of our previous work on scaling laws of x-ray and neutron production. The structure of dense plasmoids which emit MeV ions has been recorded by ion imaging with pinhole camera and contact print techniques. The plasmoids are generated in the same region in which particle beams, neutron and x-ray emission reach a maximum of intensity. Sharply defined boundaries of the ion-beam source and of plasmoids have been obtained by ion track etching on plastic material

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 flowing at 75 to 125 stdcm3/min, power between 44 and 55 W, and pressure between 50 and 100 mtorr (between 6.7 and 13.3 Pa).

Composition/bandgap selective dry photochemical etching of semiconductor materials

DOEpatents

Ashby, Carol I. H.; Dishman, James L.

1987-01-01

A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

Effects of temperature and operation parameters on the galvanic corrosion of Cu coupled to Au in organic solderability preservatives process

NASA Astrophysics Data System (ADS)

Oh, SeKwon; Kim, YoungJun; Jung, KiMin; Kim, JongSoo; Shon, MinYoung; Kwon, HyukSang

2017-03-01

In this work, we quantitatively examined the effects of temperature and operation parameters such as anode (Cu) to cathode (Au) area ratio, stirring speed, and Cu ion concentration on the galvanic corrosion kinetics of Cu coupled to Au (icouple ( Cu-Au)) on print circuit board in organic solderability preservative (OSP) soft etching solution. With the increase of temperature, galvanic corrosion rate (icouple ( Cu-Au) was increased; however, the degree of galvanic corrosion rate (icouple ( Cu-Au) - icorr (Cu)) was decreased owing to the lower activation energy of Cu coupled to Au, than that of Cu alone. With the increase of area ratio (cathode/anode), stirring speed of the system, icouple ( Cu-Au) was increased by the increase of cathodic reaction kinetics. And icouple ( Cu-Au) was decreased by the increase of the Cu-ion concentration in the OSP soft etching solution.

Laser microprobe and resonant laser ablation for depth profile measurements of hydrogen isotope atoms contained in graphite.

PubMed

Yorozu, M; Yanagida, T; Nakajyo, T; Okada, Y; Endo, A

2001-04-20

We measured the depth profile of hydrogen atoms in graphite by laser microprobing combined with resonant laser ablation. Deuterium-implanted graphite was employed for the measurements. The sample was ablated by a tunable laser with a wavelength corresponding to the resonant wavelength of 1S-2S of deuterium with two-photon excitation. The ablated deuterium was ionized by a 2 + 1 resonant ionization process. The ions were analyzed by a time-of-flight mass spectrometer. The deuterium ions were detected clearly with the resonant ablation. The detection limit was estimated to be less than 10(16) atoms/cm(3) in our experiments. We determined the depth profile by considering the etching profile and the etching rate. The depth profile agreed well with Monte Carlo simulations to within a precision of 23 mum for the center position and 4-mum precision for distributions for three different implantation depths.

The automated array assembly task of the low-cost silicon solar array project, phase 2

NASA Technical Reports Server (NTRS)

Coleman, M. G.; Pryor, R. A.; Sparks, T. G.; Legge, R.; Saltzman, D. L.

1980-01-01

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques.

Formation mechanism of graphite hexagonal pyramids by argon plasma etching of graphite substrates

NASA Astrophysics Data System (ADS)

Glad, X.; de Poucques, L.; Bougdira, J.

2015-12-01

A new graphite crystal morphology has been recently reported, namely the graphite hexagonal pyramids (GHPs). They are hexagonally-shaped crystals with diameters ranging from 50 to 800 nm and a constant apex angle of 40°. These nanostructures are formed from graphite substrates (flexible graphite and highly ordered pyrolytic graphite) in low pressure helicon coupling radiofrequency argon plasma at 25 eV ion energy and, purportedly, due to a physical etching process. In this paper, the occurrence of peculiar crystals is shown, presenting two hexagonal orientations obtained on both types of samples, which confirms such a formation mechanism. Moreover, by applying a pretreatment step with different time durations of inductive coupling radiofrequency argon plasma, for which the incident ion energy decreases at 12 eV, uniform coverage of the surface can be achieved with an influence on the density and size of the GHPs.

Fabrication of Super-Hydrophobic Microchannels via Strain-Recovery Deformations of Polystyrene and Oxygen Reactive Ion Etch.

PubMed

Chakraborty, Anirban; Xiang, Mingming; Luo, Cheng

2013-08-19

In this article, we report a simple approach to generate micropillars (whose top portions are covered by sub-micron wrinkles) on the inner surfaces of polystyrene (PS) microchannels, as well as on the top surface of the PS substrate, based on strain-recovery deformations of the PS and oxygen reactive ion etch (ORIE). Using this approach, two types of micropillar-covered microchannels are fabricated. Their widths range from 118 μm to 132 μm, depths vary from 40 μm to 44 μm, and the inclined angles of their sidewalls are from 53° to 64°. The micropillars enable these microchannels to have super-hydrophobic properties. The contact angles observed on the channel-structured surfaces are above 162°, and the tilt angles to make water drops roll off from these channel-structured substrates can be as small as 1°.

Fabrication of porous nanostructures for Raman signal amplification

NASA Astrophysics Data System (ADS)

Mitsai, E. V.; Syubaev, S. A.; Kuchmizhak, A. A.

2018-01-01

Pulsed-laser dry printing of noble-metal microrings with a tunable internal porous structure, which can be revealed via an ion-beam etching post-procedure, was demonstrated. Average size of the pores inside the microrings were shown to be tuned in a wide range by varying the incident pulse energy and a nitrogen doping level controlled in the process of magnetron deposition of the gold film in the appropriate gaseous environment. The fabricated porous microrings were shown to provide many-fold near-field enhancement of incident electromagnetic fields, which was confirmed by mapping of the characteristic Raman band of a nanometer-thick covering layer of Rhodamine 6G molecules and supporting calculations. The proposed laser-printing/ion-beam etching approach is demonstrated to be a unique tool aimed at designing and fabricating multifunctional plasmonic structures and metasurfaces for spectroscopic bioidentification based on surface-enhanced Raman scattering and photoluminescence detection schemes.

Trends in Dielectric Etch for Microelectronics Processing

NASA Astrophysics Data System (ADS)

Hudson, Eric A.

2003-10-01

Dielectric etch technology faces many challenges to meet the requirements for leading-edge microelectronics processing. The move to sub 100-nm device design rules increases the aspect ratios of certain features, imposes tighter restrictions on etched features' critical dimensions, and increases the density of closely packed arrays of features. Changes in photolithography are driving transitions to new photoresist materials and novel multilayer resist methods. The increasing use of copper metallization and low-k interlayer dielectric materials has introduced dual-damascene integration methods, with specialized dielectric etch applications. A common need is the selective removal of multiple layers which have very different compositions, while maintaining close control of the etched features' profiles. To increase productivity, there is a growing trend toward in-situ processing, which allows several films to be successively etched during a single pass through the process module. Dielectric etch systems mainly utilize capacitively coupled etch reactors, operating with medium-density plasmas and low gas residence time. Commercial technology development increasingly relies upon plasma diagnostics and modeling to reduce development cycle time and maximize performance.

Nanoparticle-based etching of silicon surfaces

DOEpatents

Branz, Howard [Boulder, CO; Duda, Anna [Denver, CO; Ginley, David S [Evergreen, CO; Yost, Vernon [Littleton, CO; Meier, Daniel [Atlanta, GA; Ward, James S [Golden, CO

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.

Comparative study of resist stabilization techniques for metal etch processing

NASA Astrophysics Data System (ADS)

Becker, Gerry; Ross, Matthew F.; Wong, Selmer S.; Minter, Jason P.; Marlowe, Trey; Livesay, William R.

1999-06-01

This study investigates resist stabilization techniques as they are applied to a metal etch application. The techniques that are compared are conventional deep-UV/thermal stabilization, or UV bake, and electron beam stabilization. The electron beam tool use din this study, an ElectronCure system from AlliedSignal Inc., ELectron Vision Group, utilizes a flood electron source and a non-thermal process. These stabilization techniques are compared with respect to a metal etch process. In this study, two types of resist are considered for stabilization and etch: a g/i-line resist, Shipley SPR-3012, and an advanced i-line, Shipley SPR 955- Cm. For each of these resist the effects of stabilization on resist features are evaluated by post-stabilization SEM analysis. Etch selectivity in all cases is evaluated by using a timed metal etch, and measuring resists remaining relative to total metal thickness etched. Etch selectivity is presented as a function of stabilization condition. Analyses of the effects of the type of stabilization on this method of selectivity measurement are also presented. SEM analysis was also performed on the features after a compete etch process, and is detailed as a function of stabilization condition. Post-etch cleaning is also an important factor impacted by pre-etch resist stabilization. Results of post- etch cleaning are presented for both stabilization methods. SEM inspection is also detailed for the metal features after resist removal processing.

One-dimension modeling on the parallel-plate ion extraction process based on a non-electron-equilibrium fluid model

NASA Astrophysics Data System (ADS)

Li, He-Ping; Chen, Jian; Guo, Heng; Jiang, Dong-Jun; Zhou, Ming-Sheng; Department of Engineering Physics Team

2017-10-01

Ion extraction from a plasma under an externally applied electric field involve multi-particle and multi-field interactions, and has wide applications in the fields of materials processing, etching, chemical analysis, etc. In order to develop the high-efficiency ion extraction methods, it is indispensable to establish a feasible model to understand the non-equilibrium transportation processes of the charged particles and the evolutions of the space charge sheath during the extraction process. Most of the previous studies on the ion extraction process are mainly based on the electron-equilibrium fluid model, which assumed that the electrons are in the thermodynamic equilibrium state. However, it may lead to some confusions with neglecting the electron movement during the sheath formation process. In this study, a non-electron-equilibrium model is established to describe the transportation of the charged particles in a parallel-plate ion extraction process. The numerical results show that the formation of the Child-Langmuir sheath is mainly caused by the charge separation. And thus, the sheath shielding effect will be significantly weakened if the charge separation is suppressed during the extraction process of the charged particles.