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Sample records for modeling euvl mask

  1. A practical approach for modeling EUVL mask defects

    SciTech Connect

    Gullikson, E.M.; Cerjan, C.; Stearns, D.J.; Mirkarimi, P.B.; Sweeney, D.W.

    2001-06-01

    An approximate method is proposed to calculate the EUV scattering from a defect within a multilayer coating. In this single surface approximation (SSA) the defective multilayer structure is replaced by a single reflecting surface with the shape of the top surface of the multilayer. The range of validity of this approximation has been investigated for Gaussian line defects using 2D finite-difference-time-domain simulations. The SSA is found to be valid for sufficiently low aspect ratio defects such as those expected for the critical defects nucleated by particles on the mask substrate. The critical EUVL defect size is calculated by combining the SSA with a multilayer growth model and aerial image simulations. Another approximate method for calculating the aerial image of an unresolved defect is also discussed. Although the critical substrate defects may be larger than the resolution of higher NA cameras, the point defect approximation provides a useful framework for understanding the printability of a wide range of defects.

  2. EUVL Mask Blank Repair

    SciTech Connect

    Barty, A; Mirkarimi, P; Stearns, D G; Sweeney, D; Chapman, H N; Clift, M; Hector, S; Yi, M

    2002-05-22

    EUV mask blanks are fabricated by depositing a reflective Mo/Si multilayer film onto super-polished substrates. Small defects in this thin film coating can significantly alter the reflected field and introduce defects in the printed image. Ideally one would want to produce defect-free mask blanks; however, this may be very difficult to achieve in practice. One practical way to increase the yield of mask blanks is to effectively repair multilayer defects, and to this effect they present two complementary defect repair strategies for use on multilayer-coated EUVL mask blanks. A defect is any area on the mask which causes unwanted variations in EUV dose in the aerial image obtained in a printing tool, and defect repair is correspondingly defined as any strategy that renders a defect unprintable during exposure. The term defect mitigation can be adopted to describe any strategy which renders a critical defect non-critical when printed, and in this regard a non-critical defect is one that does not adversely affect device function. Defects in the patterned absorber layer consist of regions where metal, typically chrome, is unintentionally added or removed from the pattern leading to errors in the reflected field. There currently exists a mature technology based on ion beam milling and ion beam assisted deposition for repairing defects in the absorber layer of transmission lithography masks, and it is reasonable to expect that this technology will be extended to the repair of absorber defects in EUVL masks. However, techniques designed for the repair of absorber layers can not be directly applied to the repair of defects in the mask blank, and in particular the multilayer film. In this paper they present for the first time a new technique for the repair of amplitude defects as well as recent results on the repair of phase defects.

  3. Electrostatic chucking and EUVL mask flatness analysis

    NASA Astrophysics Data System (ADS)

    Nataraju, M.; Mikkelson, A.; Sohn, J.; Engelstad, R. L.; Lovell, E. G.

    2005-11-01

    Successful implementation of Extreme Ultraviolet Lithography (EUVL) depends on advancements in many areas, including the quality of the mask and chuck system to control image placement (IP) errors. One source of IP error is the height variations of the patterned mask surface (i.e., its nonflatness). The SEMI EUVL mask and chucking standards (SEMI P37 and SEMI P40) describe stringent requirements for the nonflatness of the mask frontside and backside, and the chucking surfaces. Understanding and characterizing the clamping ability of the electrostatic chuck and the effect on the mask flatness is therefore critical in order to meet these requirements. Legendre polynomials have been identified as an effective and efficient means of representing EUVL mask surface shapes. Finite element (FE) models have been developed to utilize the Legendre coefficients (obtained from measured mask and chuck data) as input data to define the surfaces of the mask and the chuck. The FE models are then used to determine the clamping response of the mask and the resulting flatness of the pattern surface. The sum of the mask thickness nonuniformity and the chuck surface shape has a dominant effect on the flatness of the patterned surface after chucking. The focus of the present research is a comprehensive analysis of the flatness and interaction between the nonflat chuck and the mask. Experiments will be conducted using several sample masks chucked by a slab type electrostatic chuck. Results from the study will support and facilitate the timely development of EUVL mask/chuck systems which meet required specifications.

  4. SEMATECH EUVL mask program status

    NASA Astrophysics Data System (ADS)

    Yun, Henry; Goodwin, Frank; Huh, Sungmin; Orvek, Kevin; Cha, Brian; Rastegar, Abbas; Kearney, Patrick

    2009-04-01

    As we approach the 22nm half-pitch (hp) technology node, the industry is rapidly running out of patterning options. Of the several lithography techniques highlighted in the International Technology Roadmap for Semiconductors (ITRS), the leading contender for the 22nm hp insertion is extreme ultraviolet lithography (EUVL). Despite recent advances with EUV resist and improvements in source power, achieving defect free EUV mask blank and enabling the EUV mask infrastructure still remain critical issues. To meet the desired EUV high volume manufacturing (HVM) insertion target date of 2013, these obstacles must be resolved on a timely bases. Many of the EUV mask related challenges remain in the pre-competitive stage and a collaborative industry based consortia, such as SEMATECH can play an important role to enable the EUVL landscape. SEMATECH based in Albany, NY is an international consortium representing several of the largest manufacturers in the semiconductor market. Full members include Intel, Samsung, AMD, IBM, Panasonic, HP, TI, UMC, CNSE (College of Nanoscience and Engineering), and Fuller Road Management. Within the SEMATECH lithography division a major thrust is centered on enabling the EUVL ecosystem from mask development, EUV resist development and addressing EUV manufacturability concerns. An important area of focus for the SEMATECH mask program has been the Mask Blank Development Center (MBDC). At the MBDC key issues in EUV blank development such as defect reduction and inspection capabilities are actively pursued together with research partners, key suppliers and member companies. In addition the mask program continues a successful track record of working with the mask community to manage and fund critical mask tools programs. This paper will highlight recent status of mask projects and longer term strategic direction at the MBDC. It is important that mask technology be ready to support pilot line development HVM by 2013. In several areas progress has been

  5. Effect of electrostatic chucking on EUVL mask flatness

    NASA Astrophysics Data System (ADS)

    Mikkelson, Andrew R.; Engelstad, Roxann L.; Lovell, Edward G.; Aschke, Lutz; Rueggeberg, Frauke; Sobel, Frank

    2004-06-01

    The International Technology Roadmap for Semiconductors for Extreme Ultraviolet Lithography (EUVL) places strict requirements on the quality and flatness of the substrate and patterned mask. The SEMI EUVL Mask Substrate Standard (SEMI P37) specifies that the substrate frontside and backside nonflatness be no more than 50 nm peak-to-valley (p-v). Recent technological advances in polishing and finishing techniques have placed the 50 nm p-v specification within reach. A key ingredient in the development of EUVL is understanding and characterizing the clamping ability of the electrostatic chuck and the resulting effect on the flatness of the chucked mask. By implementing the shape of a representative EUVL mask surface into a numerical model, the effect of electrostatic chucking on the shape of the mask was determined. Legendre polynomials have been identified as an effective and efficient means of representing EUVL mask surface shapes. Finite element (FE) models have been developed to utilize the Legendre coefficients as input data to define the surfaces of an EUVL mask. The FE models were then used to determine the clamping response of the mask. In particular, the maximum mask-to-chuck gap within the Flatness Quality Area and over the entire mask has been tracked as a function of clamping pressure for representative EUVL surfaces. One of the important parameters in this study was the chuck's mechanical stiffness (comprised of the thickness and modulus). The flatness of the EUVL mask also depends on the intrinsic stress and thickness of the multilayer and backside layers. The results in this paper show that the recent advances in EUVL substrate polishing have resulted in masks that can be chucked relatively flat.

  6. EUVL mask repair: expanding options with nanomachining

    NASA Astrophysics Data System (ADS)

    Gallagher, Emily; McIntyre, Gregory; Lawliss, Mark; Robinson, Tod; Bozak, Ronald; White, Roy; LeClaire, Jeff

    2012-11-01

    Mask defectivity is often cited as a barrier to EUVL manufacturing, falling just behind low source power. Mask defectivity is a combination of intrinsic blank defects, defects introduced during the mask fabrication and defects introduced during the use of the mask in the EUV exposure tool. This paper works towards minimizing the printing impact of blank defects so that the final EUVL mask can achieve a lower defectivity. Multilayer defects can be created by a step or scratch as shallow as 1nm in the substrate. These small defects create coherent disruptions in the multilayer that can generate significant variations in mask reflectivity and induce clearly-defined, printable defects. If the optical properties of the defect can be well understood, nanomachining repair processes can be deployed to fix these defects. The purpose of this work is to develop new nanomachining repair processes and approaches that can repair complex EUVL mask defects by targeted removal of the EUVL mask materials. The first phase of this work uses nanomachining to create artificial phase defects of different types and sizes for both printability evaluation and benchmarking with simulation. Experimental results validate the concept, showing a reasonable match between imaging with the LBNL Actinic Inspection Tool (AIT) and simulation of the mask topography measured by AFM. Once the printability of various nanomachined structures is understood, the second phase of the work aims to optimize the process to repair real EUVL mask defects with surrounding absorber patterns.

  7. Electrostatic chucking of EUVL masks: coefficients of friction

    NASA Astrophysics Data System (ADS)

    Kalkowski, Gerhard; Semmler, Christian; Risse, Stefan; Peschel, Thomas; Damm, Christoph; Müller, Sandra; Bauer, René

    2010-04-01

    In extreme ultraviolet lithography (EUVL), the mask hangs on an electrostatic chuck and is moved laterally during exposition. For proper control of the chucked mask under corresponding inertial forces, static friction of the mask on the chuck is critical and an important input parameter for reliable theoretical modelling. To determine static and dynamic friction values, measurements were performed in vacuum on a mask blank with a test chuck, smaller than a real EUVL mask chuck, but otherwise nearly identical in its characteristics. Experimental results were obtained at various voltages for a materials combination of Low Thermal Expansion Glass (LTEM) for the pin chuck surface and a mask blank with a chromium metal backside metallisation, respectively. Dynamic friction was found to be only marginally smaller than static friction and values in the range from 0.27 to 0.33 were determined for the static friction coefficient under vacuum conditions.

  8. EUVL mask inspection at Hydrogen Lyman Alpha

    NASA Astrophysics Data System (ADS)

    Jota, Thiago S.; Milster, Tom D.

    2012-11-01

    Mask inspection is an outstanding challenge for Extreme Ultra-Violet Lithography (EUVL). The purpose of this investigation is to compare imaging characteristics of ArF and KrF inspection sources to imaging characteristics using a source at the Lyman-alpha line of Hydrogen at 121.6nm (HLA). HLA provides a raw resolution improvement of 37% to ArF and 51% to KrF, based on proportional wavelength scaling. The HLA wavelength is in an atmospheric transmission window, so a vacuum environment is not required. Our comparison uses rigorous vector imaging techniques to simulate partially coherent illumination schemes and reasonably accurate mask material properties and dimensions. Contrast is evaluated for representative spatial frequencies. Imaging and detection of defects are also considered with NILS and MEEF. The goal is high throughput inspection with maximum resolution, contrast, and sensitivity.

  9. Experimental verification of finite element model prediction of EUVL mask flatness during electrostatic chucking

    NASA Astrophysics Data System (ADS)

    Nataraju, Madhura; Sohn, Jaewoong; Mikkelson, Andrew R.; Turner, Kevin T.; Engelstad, Roxann L.; Van Peski, Chris K.

    2006-10-01

    Stringent flatness requirements have been imposed for the front and back surfaces of extreme ultraviolet lithography masks to ensure successful pattern transfer within the image placement error budget. During exposure, an electrostatic chuck will be used to support and flatten the mask. It is therefore critical that the electrostatic chucking process and its effect on mask flatness be well-understood. The current research is focused on the characterization of various aspects of electrostatic chucking through advanced finite element (FE) models and experiments. FE models that use flatness measurements of the mask and the chuck to predict the final flatness of the pattern surface have been developed. Pressure was applied between the reticle and chuck to simulate electrostatic clamping. The modeling results are compared to experimental data obtained using a bipolar Coulombic pin chuck. Electrostatic chucking experiments were performed in a cleanroom, within a vacuum chamber mounted on a vibration isolation cradle, to minimize the effects of particles, humidity, and static charges. During these experiments, the chuck was supported on a 3-point mount; the reticle was placed on the chuck with the backside in contact with the chucking surface and the voltage was applied. A Zygo interferometer was used to measure the flatness of the reticle before and after chucking. The FE models and experiments provide insight into the electrostatic chucking process which will expedite the design of electrostatic chucks and the development of the SEMI standards.

  10. Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

    NASA Astrophysics Data System (ADS)

    Dietze, Uwe; Dress, Peter; Waehler, Tobias; Singh, Sherjang; Jonckheere, Rik; Baudemprez, Bart

    2011-03-01

    Extreme Ultraviolet Lithography (EUVL) is considered the leading lithography technology choice for semiconductor devices at 16nm HP node and beyond. However, before EUV Lithography can enter into High Volume Manufacturing (HVM) of advanced semiconductor devices, the ability to guarantee mask integrity at point-of-exposure must be established. Highly efficient, damage free mask cleaning plays a critical role during the mask manufacturing cycle and throughout the life of the mask, where the absence of a pellicle to protect the EUV mask increases the risk of contamination during storage, handling and use. In this paper, we will present effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance, which employs an intelligent, holistic approach to maximize Mean Time Between Cleans (MBTC) and extend the useful life span of the reticle. The data presented will demonstrate the protection of the capping and absorber layers, preservation of pattern integrity as well as optical and mechanical properties to avoid unpredictable CD-linewidth and overlay shifts. Experiments were performed on EUV blanks and pattern masks using various process conditions. Conditions showing high particle removal efficiency (PRE) and minimum surface layer impact were then selected for durability studies. Surface layer impact was evaluated over multiple cleaning cycles by means of UV reflectivity metrology XPS analysis and wafer prints. Experimental results were compared to computational models. Mask life time predictions where made using the same computational models. The paper will provide a generic overview of the cleaning sequence which yielded best results, but will also provide recommendations for an efficient in-fab mask maintenance scheme, addressing handling, storage, cleaning and inspection.

  11. Mask substrate requirements and development for extreme ultraviolet lithography (EUVL)

    SciTech Connect

    Hector, S D; Shell, M; Taylor, J S; Tong, W M

    1999-09-28

    The mask is deemed one of the areas that require significant research and development in EUVL. Silicon wafers will be used for mask substrates for an alpha-class EUVL exposure tool due to their low-defect levels and high quality surface finish. However, silicon has a large coefficient of thermal expansion that leads to unacceptable image distortion due to absorption of EUV light. A low thermal expansion glass or glass-ceramic is likely to be required in order to meet error budgets for the 70nm node and beyond. Since EUVL masks are used in reflection, they are coated with multilayers prior to patterning. Surface imperfections, such as polishing marks, particles, scratches, or digs, are potential nucleation sites for defects in the multilayer coating, which could result in the printed defects. Therefore we are accelerating developments in the defect reduction and surface finishing of low thermal expansion mask substrates in order to understand long-term issues in controlling printable defects, and to establish the infrastructure for supplying masks. In this paper, we explain the technical requirements for EUVL mask substrates and describe our efforts in establishing a SEMI standard for EUVL masks. We will also report on the early progress of our suppliers in producing low thermal-expansion mask substrates for our development activities.

  12. EUVL printing results of a low-thermal expansion material (LTEM) mask

    NASA Astrophysics Data System (ADS)

    Tong, William M.; Taylor, John S.; Hector, Scott D.; Shell, Melissa K.; Zhang, Guojing; Kearney, Patrick A.; Walton, Christopher C.; Larson, Cindy C.; Wasson, James R.; Mangat, Pawitter J. S.; O'Connell, Donna J.; Folk, Daniel R.

    2000-07-01

    Minimizing image placement errors due to thermal distortion of the mask is a key requirement for qualifying EUV Lithography as a Next Generation Lithography (NGL). Employing Low Thermal Expansion Materials (LTEMs) for mask substrates is a viable solution for controlling mask thermal distortion and is being investigated by a wide array of researchers, tool makers, photomask suppliers, and material manufacturers. Finite element modeling has shown that an EUVL mask with a Coefficient of Thermal Expansion (CTE) of less than 20 ppb/K will meet overlay error budgets for EUVL masks; some of these differences are EUVL specific, while others are natural consequences of the shrinking critical dimension. We demonstrate that a feasible manufacturing pathway exists for Low Thermal Expansion Material (LTEM) EUVL masks by fabricating a wafer-shaped LTEM mask substrate using the same manufacturing steps as for fabricating Si wafers. The LTEM substrate was then coated with Mo/Si multilayers, patterned, and printed using the 10X Microstepper. The images were essentially indistinguishable from those images acquired from masks fabricated from high quality silicon wafers as substrates. Our observations lend further evidence that an LTEM can be used as the EUVL mask substrate material.

  13. Evaluation of alternative capping layers for EUVL mask ML blank

    NASA Astrophysics Data System (ADS)

    Yan, Pei-yang; Spiller, Eberhard; Gullikson, Eric; Hill, Shannon

    2005-11-01

    The standard silicon (Si) capping layer used for extreme ultra-violet lithography (EUVL) multilayer (ML) mask blanks has some shortcomings, such as low oxidation resistance, low chemical resistance, low etch selectivity in either the SiO2 buffer layer etch to the capping layer or the absorber etch (e.g., TaN) to the capping layer. These performance and process issues with Si capped ML mask blank will reduce the mask lifetime and require tighter process control during EUVL mask fabrication. Alternative capping materials have been investigated for both EUVL optics and for mask applications.1-5 It has been initially demonstrated that Ru capping layers have high oxidation resistance and high mask process margin as compared to Si ML cap. In this paper, we will present a detailed evaluation of Ru and ion beam deposited (IBD) diamond-like-carbon (DLC) for EUVL mask application. Performance evaluations of the DLC mask blank capping layer and Ru capping layer were made in the area of reflectivity performance, shelf-life, and EUV exposure stability. It has been shown that EUV exposure induced capping layer change depends upon the exposure conditions. However, we found that as long as the induced relative change in the ML cap material are the same (e.g., the same amount of oxidation), regardless of exposure time and exposure conditions, the resulting reflectivity change is about the same. In the case of the two capping layer materials we evaluated, the capping surface reaction with active oxygen is the primary cause for the reflectivity degradation.

  14. Advances in Low-Defect Multilayers for EUVL Mask Blanks

    SciTech Connect

    Folta, J A; Davidson, J C; Larson, C C; Walton, C C; Kearney, P A

    2002-04-15

    Low-defect multilayer coatings are required to fabricate mask blanks for Extreme Ultraviolet Lithography (EUVL). The mask blanks consist of high reflectance E W multilayers on low thermal expansion substrates. A defect density of 0.0025 printable defects/cm{sup 2} for both the mask substrate and the multilayer is required to provide a mask blank yield of 60%. Current low defect multilayer coating technology allows repeated coating-added defect levels of 0.05/cm{sup 2} for defects greater than 90 nm polystyrene latex sphere (PSL) equivalent size for lots of 20 substrates. Extended clean operation of the coating system at levels below 0.08/cm{sup 2} for 3 months of operation has also been achieved. Two substrates with zero added defects in the quality area have been fabricated, providing an existence proof that ultra low defect coatings are possible. Increasing the ion source-to-target distance from 410 to 560 mm to reduce undesired coating of the ion source caused the defect density to increase to 0.2/cm{sup 2}. Deposition and etching diagnostic witness substrates and deposition pinhole cameras showed a much higher level of ion beam spillover (ions missing the sputter target) than expected. Future work will quantify beam spillover, and test designs to reduce spillover, if it is confirmed to be the cause of the increased defect level. The LDD system will also be upgraded to allow clean coating of standard format mask substrates. The upgrade will confirm that the low defect process developed on Si wafers is compatible with the standard mask format 152 mm square substrates, and will provide a clean supply of EUVL mask blanks needed to support development of EUVL mask patterning processes and clean mask handling technologies.

  15. Characterization of electrostatically chucked EUVL mask blanks

    NASA Astrophysics Data System (ADS)

    Ligman, Rebekah K.; Shu, Emily Y.; Yan, Pei-yang

    2005-05-01

    The flatness of electrostatically chucked EUVL reticles was evaluated on two Zerodur bipolar coulombic electrostatic chucks (from Invax Technologies) of different thicknesses, which represent different chuck stiffness, different hardness of the dielectric material used for chuck surface, and different surface flatness finishing. A Zygo GPI interferometer was used to measure the flatness of the chucked reticles, freestanding reticles, and chuck surfaces. The chucked reticle flatness was impacted by the flatness and shape of the front and back sides of the reticle and that of the chuck. Chucked reticle dynamics during chucking and reticle hysterisis were observed. A stable operation range for the e-chucks was found. We also observed backside-particle-induced-out of plane distortion (OPD) on the chucked reticle in the experiments when Cu particles of height 1 to 3μm were placed between the chuck and the reticle backside.

  16. Actinic defect counting statistics over 1 cm2 area of EUVL mask blank

    SciTech Connect

    Jeong, Seongtae; Lai, Chih-Wei; Rekawa, Seno; Walton, Chris W.; Bokor, Jeffrey

    2000-02-18

    As a continuation of comparison experiments between EUV inspection and visible inspection of defects on EUVL mask blanks, we report on the result of an experiment where the EUV defect inspection tool is used to perform at-wavelength defect counting over 1 cm{sup 2} of EUVL mask blank. Initial EUV inspection found five defects over the scanned area and the subsequent optical scattering inspection was able to detect all of the five defects. Therefore, if there are any defects that are only detectable by EUV inspection, the density is lower than the order of unity per cm2. An upgrade path to substantially increase the overall throughput of the EUV inspection system is also identified in the manuscript.

  17. Challenges for 1x-nm device fabrication using EUVL: scanner and mask

    NASA Astrophysics Data System (ADS)

    Arnold, William H.

    2011-11-01

    EUVL lithography using high resolution step and scan systems operating at 13.5nm is being inserted in leading edge production lines for memory and logic devices. These tools use mirror optics and either laser produced plasma (LPP) or discharge produced plasma (DPP) sources along with reflective reduction masks to image circuit features. These tools show their capability to meet the challenging device requirements for imaging and overlay. Next generation scanners with resolution and overlay capability to produce 1X nm (10 nm class) memory and logic devices are in preparation. Challenges remain for EUVL, the principal of which are increasing source power enabling high productivity, building a volume mask business encouraging rapid learning cycles, and improving resist performance so it is capable of sub 20nm resolution.

  18. Particle transport in plasma systems for development of EUVL mask blanks

    NASA Astrophysics Data System (ADS)

    Stoltz, Peter; Likhanskii, Alex; Zhou, Chuandong; Jindal, Vibhu; Kearney, Patrick

    2012-11-01

    Defect transport in development of EUVL mask blanks is an important issue for the near-term of the industry. One main issue affecting transport is how the defect may charge in the presence of plasma. In some cases, plasma may act to contain defects away from the mask surface. We show simulation results of the effect of plasma on defect transport demonstrating how the formation of plasma sheathes and a plasma potential act to confine highly negatively charged particles, such as defect particles would be.

  19. Performance of actinic EUVL mask imaging using a zoneplatemicroscope

    SciTech Connect

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Barty, Anton; Rekawa,Senajith B.; Kemp, Charles D.; Gunion, Robert F.; Salmassi, Farhad; Gullikson, Eric M.; Anderson, Erik H.; Han, Hak-Seung

    2007-08-20

    The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a dual-mode, scanning and imaging extreme-ultraviolet (EUV) microscope designed for pre-commercial EUV mask research. Dramatic improvements in image quality have been made by the replacement of several critical optical elements, and the introduction of scanning illumination to improve uniformity and contrast. We report high quality actinic EUV mask imaging with resolutions as low as 100-nm half-pitch, (20-nm, 5x wafer equivalent size), and an assessment of the imaging performance based on several metrics. Modulation transfer function (MTF) measurements show high contrast imaging for features sizes close to the diffraction-limit. An investigation of the illumination coherence shows that AIT imaging is much more coherent than previously anticipated, with {sigma} below 0.2. Flare measurements with several line-widths show a flare contribution on the order of 2-3% relative intensity in dark regions above the 1.3% absorber reflectivity on the test mask used for these experiments. Astigmatism coupled with focal plane tilt are the dominant aberrations we have observed. The AIT routinely records 250-350 high-quality images in numerous through-focus series per 8-hour shift. Typical exposure times range from 0.5 seconds during alignment, to approximately 20 seconds for high-resolution images.

  20. Performance of actinic EUVL mask imaging using a zoneplate microscope

    SciTech Connect

    Goldberg, K; Naulleau, P; Barty, A; Rekawa, S; Kemp, C; Gunion, R; Salmassi, F; Gullikson, E; Anderson, E; Han, H

    2007-09-25

    The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a dual-mode, scanning and imaging extreme-ultraviolet (EUV) microscope designed for pre-commercial EUV mask research. Dramatic improvements in image quality have been made by the replacement of several critical optical elements, and the introduction of scanning illumination to improve uniformity and contrast. We report high quality actinic EUV mask imaging with resolutions as low as 100-nm half-pitch, (20-nm, 5x wafer equivalent size), and an assessment of the imaging performance based on several metrics. Modulation transfer function (MTF) measurements show high contrast imaging for features sizes close to the diffraction-limit. An investigation of the illumination coherence shows that AIT imaging is much more coherent than previously anticipated, with {sigma} below 0.2. Flare measurements with several line-widths show a flare contribution on the order of 2-3% relative intensity in dark regions above the 1.3% absorber reflectivity on the test mask used for these experiments. Astigmatism coupled with focal plane tilt are the dominant aberrations we have observed. The AIT routinely records 250-350 high-quality images in numerous through-focus series per 8-hour shift. Typical exposure times range from 0.5 seconds during alignment, to approximately 20 seconds for high-resolution images.

  1. Performance in practical use of actinic EUVL mask blank inspection

    NASA Astrophysics Data System (ADS)

    Yamane, Takeshi; Kim, Yongdae; Takagi, Noriaki; Terasawa, Tsuneo; Ino, Tomohisa; Suzuki, Tomohiro; Miyai, Hiroki; Takehisa, Kiwamu; Kusunose, Haruhiko

    2014-07-01

    A high-volume manufacturing (HVM) actinic blank inspection (ABI) prototype has been developed, of which the inspection capability for a native defect was evaluated. An analysis of defect signal intensity (DSI) analysis showed that the DSI varied as a result of mask surface roughness. Operating the ABI under a review mode reduced that variation by 71 %, and therefore this operation was made available for precise DSI evaluation. The result also indicated that the defect capture rate was influenced by the DSI variation caused by mask surface roughness. A mask blank was inspected three times by the HVM ABI prototype, and impact of the detected native defects on wafer CD was evaluated. There was observed a pronounced relationship between the DSI and wafer CD; and this means that the ABI tool could detect wafer printable defects. Using the total DSI variation, the capture rate of the smallest defect critical for 16 nm node was estimated to be 93.2 %. This means that most of the critical defects for 16 nm node can be detected with the HVM ABI prototype.

  2. Evaluation of EUVL mask pattern defect inspection using 199nm inspection tool with super-resolution method

    NASA Astrophysics Data System (ADS)

    Shigemura, Hiroyuki; Amano, Tsuyoshi; Nishiyama, Yasushi; Suga, Osamu; Arisawa, Yukiyasu; Hashimoto, Hideaki; Takahara, Kenichi; Usuda, Kinya; Kikuiri, Nobutaka; Hirano, Ryoichi

    2009-04-01

    In this paper, we will report on our experimental and simulation results on the impact of EUVL mask absorber structure and of inspection system optics on mask defect detection sensitivity. We employed a commercial simulator EM-Suite (Panoramic Technology, Inc.) which calculated rigorously using FDTD (Finite-difference time-domain) method. By using various optical constants of absorber stacks, we calculated image contrasts and defect image signals as obtained from the mask defect inspection system. We evaluated the image contrast and the capability of detecting defects on the EUVL masks by using a new inspection tool made by NuFlare Technology, Inc. (NFT) and Advanced Mask Inspection Technology, Inc. (AMiT). This tool is based on NPI-5000 which is the leading-edge photomask defect inspection system using 199nm wavelength inspection optics. The programmed defect masks with LR-TaBN and LRTaSi absorbers were used which had various sized opaque and clear extension defects on hp-160nm, hp-225nm, and hp- 325nm line and space patterns. According to the analysis, reflectivity of EUVL mask absorber structures and the inspection optics have large influence on image contrast and defect sensitivity. It is very important to optimize absorber structure and inspection optics for the development of EUVL mask inspection technology, and for the improvement of performance of EUV lithographic systems.

  3. The study of EUVL mask defect inspection technology for 32-nm half-pitch node device and beyond

    NASA Astrophysics Data System (ADS)

    Shigemura, Hiroyuki; Amano, Tsuyoshi; Nishiyama, Yasushi; Suga, Osamu; Terasawa, Tsuneo; Arisawa, Yukiyasu; Hashimoto, Hideaki; Kameya, Norio; Takeda, Masaya; Kikuiri, Nobutaka; Hirano, Ryoichi; Hirono, Masatoshi

    2008-10-01

    In this paper, we will report on our experimental and simulation results on the impact of EUVL mask absorber structure and of inspection system optics on mask defect detection sensitivity. We employed a commercial simulator EM-Suite (Panoramic Technology, Inc.) which calculated rigorously using FDTD (Finite-difference time-domain) method. By using various optical constants of absorber stacks, we calculated image contrasts and defect image signals as obtained from the mask defect inspection system. We evaluated the image contrast and the capability of detecting defects on the EUVL masks by using a new inspection tool made by NuFlare Technology, Inc. (NFT) and Advanced Mask Inspection Technology, Inc. (AMiT). This tool is based on NPI-5000 which is the leading-edge photomask defect inspection system using 199nm wavelength inspection optics. The programmed defect masks with LR-TaBN and LRTaSi absorbers were used which had various sized opaque and clear extension defects on hp-160nm, hp-225nm, and hp- 325nm line and space patterns. According to the analysis, reflectivity of EUVL mask absorber structures and the inspection optics have large influence on image contrast and defect sensitivity. It is very important to optimize absorber structure and inspection optics for the development of EUVL mask inspection technology, and for the improvement of performance of EUV lithographic systems.

  4. Study of EUVL mask defect inspection using 199-nm inspection tool with super-resolution method

    NASA Astrophysics Data System (ADS)

    Shigemura, Hiroyuki; Amano, Tsuyoshi; Arisawa, Yukiyasu; Suga, Osamu; Hashimoto, Hideaki; Saito, Masanori; Takeda, Masaya; Kikuiri, Nobutaka; Hirano, Ryoichi

    2009-10-01

    In this paper, we will report on our experimental results on the impact of inspection system optics on mask defect detection sensitivity. We evaluated the capability of detecting defects on the EUVL masks by using a new inspection tool (NPI6000EUVα) made by NuFlare Technology, Inc. (NFT) and Advanced Mask Inspection Technology, Inc. (AMiT). This tool is based on NPI-5000 which is the leading-edge photomask defect inspection system using 199nm wavelength inspection optics. The programmed defect mask with LR-TaBN absorber was used which had various sized opaque and clear extension defects on hp-180nm, hp-128nm, and hp-108nm line and space patterns. According to the analysis, to obtain optimum sensitivity for various types of defects, using both C- and P-polarized illumination conditions were found to be effective. At present, sufficient defect-detection sensitivity is achieved for opaque and clear extension defects in hp128nm (hp32nm at wafer). For hp108nm (hp27nm at wafer), using both C- and P- polarized illumination is effective. However, further developments in defect-detection sensitivity are necessary.

  5. Analytical treatment of the deformation behavior of EUVL masks during electrostatic chucking

    NASA Astrophysics Data System (ADS)

    Brandstetter, Gerd; Govindjee, Sanjay

    2012-03-01

    A new analytical approach is presented to predict mask deformation during electro-static chucking in next generation extreme-ultraviolet-lithography (EUVL). Given an arbitrary profile measurement of the mask and chuck non-flatness, this method has been developed as an alternative to time-consuming finite element simulations for overlay error correction algorithms. We consider the feature transfer of each harmonic component in the profile shapes via linear elasticity theory and demonstrate analytically how high spatial frequencies are filtered. The method is compared to presumably more accurate finite element simulations and has been tested successfully in an overlay error compensation experiment, where the residual error y-component could be reduced by a factor 2. As a side outcome, the formulation provides a tool to estimate the critical pin-size and -pitch such that the distortion on the mask front-side remains within given tolerances. We find for a numerical example that pin-pitches of less than 5 mm will result in a mask pattern-distortion of less than 1 nm if the chucking pressure is below 30 kPa.

  6. Report on EUVL Mask Substrate Development: Low-Expansion Substrate Finishing II

    SciTech Connect

    Tong, W.M.; Taylor, J.S.; Hector, S.D.; Shell, M.

    1999-12-08

    This report is a continuation of our assessment of the finishing of low thermal expansion material wafers obtained through three different commercial pathways. This quarter we have patterned and printed a ULE{reg_sign} wafer (Rodel 1) and saw no difference between its images and those from silicon wafer substrates. This further demonstrated that ULE{reg_sign} can be used as the EUVL mask substrate material. We have also evaluated substrates produced by three vendors: Hoya, General Optics, and Rodel. Consistent with our results reported last quarter, surface roughness of the bare substrates from all three companies does not depend on the position. For Hoya, the wafers it produced had a low roughness than those from last quarter. However, the cleanliness of the wafers needs to be improved. For General Optics, the wafer roughness has increased, and it was only able to deliver one wafer this quarter. General Optics will be replaced by Schott ML next quarter. For Rodel, one of its wafers (Rodel 1) that had been cleaned in-house showed excellent finishing and was selected to be patterned. We also observed that the sleeks on the substrates were smoothed by the ML coating. The other two Rodel wafers (Rodel 2 and Rodel 4) had too many defects and the roughness values derived from AFM are not reliable.

  7. Status of fabrication of square-format masks for extreme-ultraviolet lithography (EUVL) at the MCoC

    NASA Astrophysics Data System (ADS)

    Racette, Kenneth C.; Williams, Carey T.; Fisch, Emily; Kindt, Louis; Lawliss, Mark; Ackel, Robin; Lercel, Michael J.

    2002-07-01

    Fabricating masks for extreme ultraviolet lithography is challenging. The high absorption of most materials at 13.4 nm and the small critical dimension (45 nm) at the target insertion node force many new features, including reflective mask design, new film choices, and stringent defect specifications. Fabrication of these masks requires the formation and patterning of both a repair buffer layer and an EUV absorber layer on top of a molybdenum/silicon multi-layer substrate. IBM and Photronics have been engaged in developing mask processing technology for x-ray, electron beam projection and extreme ultraviolet lithographies at the Next Generation Lithography Mask Center of Competency (NGL-MCoC) within IBM's mask facility at Essex Junction, Vermont. This paper describes recent results of mask fabrication on 6 x 6 x 1/4 inch EUVL substrates (quartz with molybdenum silicon multi-layers) at the MCoC. Masks fabricated with high and low-stress chromium and externally deposited chromium absorber films are compared. In particular, etch characteristics, image size, image placement, line edge roughness, and defect levels are presented and compared. Understanding the influence of the absorber film characteristics on these parameters will enable us to optimize the effectiveness of a given absorber film or to select acceptable alternatives.

  8. Status of EUVL reticle chucking

    NASA Astrophysics Data System (ADS)

    Engelstad, Roxann L.; Sohn, Jaewoong; Zeuske, Jacob R.; Battula, Venkata Siva; Vukkadala, Pradeep; Van Peski, Chris K.; Orvek, Kevin J.; Turner, Kevin T.; Mikkelson, Andrew R.; Nataraju, Madhura

    2008-04-01

    Extreme Ultraviolet Lithography (EUVL) is one of the leading candidates for Next-Generation Lithography in the sub-45-nm regime. Successful implementation of this technology will depend upon advancements in many areas, including the quality of the mask system to control image placement errors. For EUVL, the nonflatness of both the mask and chuck is critical, due to the nontelecentric illumination during exposure. The industry is proposing to use an electrostatic chuck to support and flatten the mask in the exposure tool. The focus of this research is to investigate the clamping ability of a pin-type chuck, both experimentally and with the use of numerical simulation tools, i.e., finite element modeling. A status report on electrostatic chucking is presented, including the results obtained during repeatability studies and long-term chucking experiments.

  9. Experimental validation of a thermal model used to predict the image placement error of a scanned EUVL reticle

    NASA Astrophysics Data System (ADS)

    Gianoulakis, Steven E.; Craig, Marcus J.; Ray-Chaudhuri, Avijit K.

    2000-07-01

    Lithographic masks must maintain dimensional stability during exposure in a lithographic tool to minimize subsequent overlay errors. In extreme ultraviolet lithography (EUVL), multilayer coatings are deposited on a mask substrate to make the mask surface reflective at EUV wavelengths. About 40% of the incident EUV light is absorbed by the multilayer coating which leads to a temperature rise. The choice of mask substrate material and absorber affects the magnitude of thermal distortion. Finite element modeling has been used to investigate potential mask materials and to explore the efficiency of various thermal management strategies. An experimental program was conducted to validate the thermal models used to predict the performance of EUV reticles. The experiments closely resembled actual conditions expected within the EUV tool. A reticle instrumented with temperature sensors was mounted on a scanning stage with an electrostatic chuck. An actively cooled isolation plate was mounted in front of the reticle for thermal management. Experimental power levels at the reticle corresponding to production throughput levels were utilized in the experiments. Both silicon and low expansion glass reticles were tested. Temperatures were measured a several locations on the reticle and tracked over time as the illuminated reticle was scanned. The experimental results coupled with the predictive modeling capability validates that the assertion that the use of a low expansion glass will satisfy image placement error requirements down to the 30 nm lithographic node.

  10. Investigation and prediction of image placement errors in extreme ultraviolet lithography masks

    NASA Astrophysics Data System (ADS)

    Zheng, Liang

    2010-11-01

    According to the latest ITRS Roadmap, extreme ultraviolet lithography (EUVL) is expected to be one of the principal carriers for the IC production at sub-45 nm technology nodes. One of the most challenging tasks to fulfill EUVL is the fabrication of the EUVL mask in which the most important issue is the control of image placement errors. In this paper, the EUVL mask fabrication process was analyzed and image placement errors due to the fabrication process were investigated and predicted. A theoretical analysis was conducted to analytically benchmark the EUVL mask fabrication process. A line-and-space pattern (with pattern coverage of 50%) was employed in the theoretical analysis as an example. The theoretical deduction revealed that this 50% coverage pattern produces the same global response as a uniformly stressed thin film with half of the stress-thickness product of the patterned lines. Finite element (FE) models were established to simulate the EUVL mask fabrication process. In FE simulations, a new equivalent modeling technique was developed to predict the global distortions of the mask and the local distortions of the pattern features. Results indicate that for the EUVL mask with this line-and-space pattern (50% pattern coverage), the maximum image placement error is only about 10 nm, which is largely due to the application of a flat electrostatic chuck in both e-beam mounting and exposure chucking. Nonuniformities of either the mask or the electrostatic chuck will add to the final image placement errors of the EUVL mask.

  11. Predicting the influence of trapped particles on EUVL reticle distortion during exposure chucking

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Vasu; Turner, Kevin T.; Engelstad, Roxann L.; Lovell, Edward G.

    2006-10-01

    Among the potential sources of image placement (IP) error for extreme ultraviolet lithography (EUVL) is the deformation of the mask during electrostatic chucking. This paper focuses on the in-plane and out-of-plane distortion of the EUVL reticle due to the entrapment of particles. Localized finite element (FE) models have been developed to simulate the micro response of the reticle / particle / chuck system. To identify the macro response, global FE models have been generated to simulate the system under typical chucking conditions. Parametric studies were performed to illustrate the effect of particle size on the final IP accuracy.

  12. Electrostatic chucking of EUVL reticles

    NASA Astrophysics Data System (ADS)

    Nataraju, Madhura; Sohn, Jaewoong; Mikkelson, Andrew R.; Engelstad, Roxann L.; Turner, Kevin T.; Van Peski, Chris K.; Orvek, Kevin J.

    2007-03-01

    Characterizing the effect of electrostatic chucking on the flatness of Extreme Ultraviolet Lithography (EUVL) reticles is necessary for the implementation of EUVL for the sub-32 nm node. In this research, finite element (FE) models have been developed to predict the flatness of reticles when clamped by a bipolar Coulombic pin chuck. Nonflatness measurements of the reticle and chuck surfaces were used to create the model geometry. Chucking was then simulated by applying forces consistent with the pin chuck under consideration. The effect of the nonuniformity of electrostatic forces due to the presence of gaps between the chuck and reticle backside surfaces was also included. The model predictions of the final pattern surface shape of the chucked reticle have been verified with chucking experiments and the results have established the validity of the models. Parametric studies with varying reticle shape, chuck shape, chuck geometry, and chucking pressure performed using FE modeling techniques are extremely useful in the development of SEMI standards for EUVL.

  13. Nikon EUVL development progress update

    NASA Astrophysics Data System (ADS)

    Miura, Takaharu; Murakami, Katsuhiko; Suzuki, Kazuaki; Kohama, Yoshiaki; Morita, Kenji; Hada, Kazunari; Ohkubo, Yukiharu; Kawai, Hidemi

    2008-03-01

    Extreme Ultra Violet Lithography (EUVL) has been widely regarded as the lithography technology to succeed optical lithography. It is now considered as one of the most promising technologies below hp45nm node [1], following ArF immersion lithography considering trend of achievable process K1 factors. In this paper we would like to present our significant progress on the development of EUV exposure tool. There are several key important areas which should be developed to realize EUVL to be feasible, such as reflective mask, resist, and tool itself. The reflective mask features such characteristics as pellicle-less, ultra-smooth blank flatness and defect free. The resist should be of high sensitivity and small line edge roughness (LER) as well as fine resolution. EUV exposure tool itself consists of major modules such as EUV light source, projection optics, vacuum body, vacuum stages, and so on. Nikon has developed new polishing technologies such as ion-beam figuring and elastic emission machining, and new ultra high-precision interferometers for aspheric surface metrology. Our multi-layer coating technology has been also improved. High reflective Mo/Si multi layer coating has been successfully achieved and irradiation tests using synchrotron radiation have been conducted. Successful achievement of those developments enables us to produce full-field projection optics for EUVL process development tool called EUV1. The proto-type development of full-field projection optics has been successfully completed and its technical achievement has reflected into production optics. Preparation of complete set of production and metrology tools necessary for projection optics production was completed and all tools are now in full operation. Nikon has already developed dual pod reticle carrier for EUV1 tool. In parallel Nikon has been developing the same concept carrier for HVM in cooperation with Canon and Entegris. Regarding to EUV1 tool development, all modules of EUV1 such as full

  14. Process liability evaluation for EUVL

    NASA Astrophysics Data System (ADS)

    Aoyama, Hajime; Tawarayama, Kazuo; Tanaka, Yuusuke; Kawamura, Daisuke; Arisawa, Yukiyasu; Uno, Taiga; Kamo, Takashi; Tanaka, Toshihiko; Itani, Toshiro; Tanaka, Hiroyuki; Nakajima, Yumi; Inanami, Ryoichi; Takai, Kosuke; Murano, Koji; Koshiba, Takeshi; Hashimoto, Kohji; Mori, Ichiro

    2009-03-01

    This paper concerns the readiness of extreme ultraviolet lithography (EUVL) for high-volume manufacture based on accelerated development in critical areas and the construction of a process liability (PL) test site that integrates results in these areas. The overall lithography performance was determined from the performance of the exposure tool, the printability obtainable with the resist, mask fabrication with accurate critical dimension (CD) control, and correction technology for mask data preparation. The EUV1 exposure tool can carry out exposure over the full field (26 mm × 33 mm) at a resolution high enough for 32-nm line-and-space patterns when Selete Standard Resist 3 (SSR3) is used. Thus, the test site was designed for the full-field exposure of various pattern sizes [half-pitch (hp) 32-50 nm]. The CD variation of the mask was found to be as good as 2.8 nm (3σ) and only one printable defect was detected. The effect of flare on CD variation is a critical issue in EUVL; so flare was compensated for based on the point spread function for the projection optics of the EUV1 and aerial simulations that took resist blur into account. The accuracy obtained when an electronic design automation (EDA) tool was used for mask resizing was found to be very good (error <= +/-2 nm). Metal wiring patterns with a size of hp 32 nm were successfully formed by wafer processing. The production readiness of EUVL based on the integration of results in these areas was evaluated by electrical tests on low-resistance tungsten wiring. The yield for the electrically open test for hp 50 nm (32-nm logic node) and hp 40 nm (22-nm logic node) were found to be over 60% and around 50%, respectively; and the yield tended to decrease as patterns became smaller. We found the PL test site to be very useful for determining where further improvements need to be made and for evaluating the production readiness of EUVL.

  15. Optics and multilayer coatings for EUVL systems

    SciTech Connect

    Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

    2008-03-21

    EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

  16. Challenges and solutions ensuring EUVL photomask integrity

    NASA Astrophysics Data System (ADS)

    Brux, O.; Dreß, P.; Schmalfuß, H.; Jonckheere, R.; Koolen-Hermkens, W.

    2012-06-01

    Industry roadmaps indicate that the introduction of Extreme Ultraviolet Lithography (EUVL) is on track for high volume manufacturing. Although, there has been significant progress in each of the individual subsets of the EUVL infrastructure, the absolute management of the process outside of the scanner and up to the point-of-exposure has been highlighted as critical requirement for the adoption of EUVL. Significant changes in the EUV system environment and mask architecture are driving a zero process tolerance level. Any unforeseen contamination introduced to the scanner environment from the EUV mask could cause considerable downtime and yield loss. Absolute mask integrity at the point-of-exposure must be guaranteed. EUV mask cleaning processes-of-record have been developed and introduced to the industry [1]. The issue is not longer "how to clean the mask" but, "how to keep it clean". With the introduction of EUVL, mask cleanliness extends out beyond the traditional mask cleaning tool. Complete control of contamination and/or particles during transportation, handling and storage will require a holistic approach to mask management. A new environment specifically for EUV mask integrity must be developed and fully tested for the sub 16nm half-pitch node introduction. The SUSS MaskTrack Pro (MTP) InSync was introduced as the solution for EUV mask integrity. SUSS demonstrated the fully automated handling of EUV masks into and out of a Dual Pod System [2]. Intrinsic cleanliness of each individual handling and storage step of the inner pod (EIP) and EUV mask inside the MTP InSync Tool was investigated and reported. A target specification of a PRP <= 0.08 as criterion for the cross contamination between EIP and the EUV reticle during handling within MTP InSync has been achieved and therefore proofing the applicability for the Dual Pod automation. Moreover an appropriate automated handling, other aspects like backside particle contamination and EIP cleanliness plays a

  17. Accurate mask model for advanced nodes

    NASA Astrophysics Data System (ADS)

    Zine El Abidine, Nacer; Sundermann, Frank; Yesilada, Emek; Ndiaye, El Hadji Omar; Mishra, Kushlendra; Paninjath, Sankaranarayanan; Bork, Ingo; Buck, Peter; Toublan, Olivier; Schanen, Isabelle

    2014-07-01

    Standard OPC models consist of a physical optical model and an empirical resist model. The resist model compensates the optical model imprecision on top of modeling resist development. The optical model imprecision may result from mask topography effects and real mask information including mask ebeam writing and mask process contributions. For advanced technology nodes, significant progress has been made to model mask topography to improve optical model accuracy. However, mask information is difficult to decorrelate from standard OPC model. Our goal is to establish an accurate mask model through a dedicated calibration exercise. In this paper, we present a flow to calibrate an accurate mask enabling its implementation. The study covers the different effects that should be embedded in the mask model as well as the experiment required to model them.

  18. Nikon EUVL development progress update

    NASA Astrophysics Data System (ADS)

    Miura, Takaharu; Murakami, Katsuhiko; Suzuki, Kazuaki; Kohama, Yoshiaki; Morita, Kenji; Hada, Kazunari; Ohkubo, Yukiharu

    2007-03-01

    Extreme Ultra Violet Lithography (EUVL) has been widely regarded as the lithography technology to succeed optical lithography. It is now considered as one of the most promising technologies below hp45nm node [1], following ArF immersion lithography considering trend of achievable process K1 factors shown in Fig. 1. In this paper we would like to present significant progress on the development of EUV exposure tool. There are several key important areas which should be developed to realize EUVL to be feasible such as reflective mask, resist, and tool itself. The reflective mask features such characteristics as pellicle-less, ultra-smooth blank flatness and defect free. The resist should be of high sensitivity and small line edge roughness (LER) as well as fine resolution. EUV exposure tool itself consists of major modules such as EUV light source, projection optics, vacuum body, vacuum stages, and so on. As far as EUVL optics development is concerned, through the development of high-NA small-field EUV exposure system (HiNA) in conjunction with EUVA (Extreme Ultraviolet Lithography System Development Association) projects, we have developed new polishing technologies such as ion-beam figuring and elastic emission machining, and new ultra high-precision interferometers for aspheric surface metrology. Wave front sensor system has been also developed partly in EUVA project. A new wave front sensor system which can be used for evaluating the projection optics with EUV light has already been installed in New SUBARU synchrotron facility in University of Hyogo. Our multi-layer coating technology has been also improved. High reflective Mo/Si multi layer coating has been successfully achieved and irradiation tests using synchrotron radiation have been conducted [8]. Successful achievement of those developments enables us to produce full-field projection optics for EUVL process development tool called EUV1. Proto-type development of full-field projection optics has been

  19. Properties and performance of EUVL pellicle membranes

    NASA Astrophysics Data System (ADS)

    Gallagher, Emily E.; Vanpaemel, Johannes; Pollentier, Ivan; Zahedmanesh, Houman; Adelmann, Christoph; Huyghebaert, Cedric; Jonckheere, Rik; Lee, Jae Uk

    2015-10-01

    EUV mask protection during handling and exposure remains a challenge for high volume manufacturing using EUV scanners. A thin, transparent membrane can be mounted above the mask pattern so that any particle that falls onto the front of the mask is held out of focus and does not image. The fluoropolymer membranes that are compatible with 193nm lithography absorb too strongly at the 13.5nm EUV exposure wavelength to be considered. Initially, the industry planned to expose EUV masks without any pellicle; however, the time and cost of fabricating and qualifying an EUV mask is simply too high to risk decimating wafer yield each time a particle falls onto the mask pattern. Despite the challenges of identifying a membrane for EUV, the industry has returned to the pellicle concept for protection. EUVL pellicles have been in development for more than a decade and reasonable options exist. Meeting all pellicle requirements is difficult, so this type of risk-mitigation effort is needed to ensure that there is a viable high-volume manufacturing option. This paper first reviews the desired membrane properties for EUVL pellicles. Next, candidate materials are introduced based on reported properties and compatibility with fabrication. Finally a set of candidate membranes are fabricated. These membranes are screened using a simplified set of tests to assess their suitability as an EUV pellicle. EUV transmission, film stress, and film durability data are included. The results are presented along with general guidelines for pellicle membrane properties for EUV manufacturing.

  20. Optimization of EUVL reticle thickness for image placement accuracy

    NASA Astrophysics Data System (ADS)

    Zheng, Liang; Mikkelson, Andrew R.; Abdo, Amr Y.; Engelstad, Roxann L.; Lovell, Edward G.; White, Thomas J.

    2003-12-01

    Extreme ultraviolet lithography (EUVL) is one of the leading candidates for next-generation lithography in the sub-65 nm regime. The International Technology Roadmap for Semiconductors proposes overlay error budgets of 18 nm and 13 nm for the 45 nm and 32 nm nodes, respectively. Full three-dimensional finite element (FE) models were developed to identify the optimal mask thickness to minimize image placement (IP) errors. Five thicknesses of the EUVL reticle have been investigated ranging from 2.3 mm to 9.0 mm. The mask fabrication process was simulated, as well as the e-beam mounting, pattern transfer, and exposure mounting, utilizing FE structural models. Out-of-plane distortions and in-plane distortions were tracked for each process step. Both electrostatic and 3-point mounts were considered for the e-beam tool and exposure tool. In this case, increasing the thickness of the reticle will reduce the magnitude of the distortions. The effect of varying the reticle thickness on chucking was also studied. FE models were utilized to predict how changing the reticle thickness would affect the overall clamping response. By decreasing the reticle thickness (and therefore the effective bending stiffness), the deformed reticle is easier to flatten during chucking. In addition, the thermomechanical response of the reticle during exposure was investigated for different reticle thicknesses. Since conduction to the chuck is the main heat dissipation mechanism, decreasing the reticle thickness results in more energy being conducted away from the reticle, which reduces the maximum temperature rise and the corresponding thermal distortion. The FE simulations illustrate the optimal thickness to keep IP errors within the allotted error budget as well as provide the necessary flatness during typical chucking procedures.

  1. Evaluating printability of buried native EUV mask phase defects through a modeling and simulation approach

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Mihir; Jindal, Vibhu; Basavalingappa, Adarsh; Herbol, Henry; Harris-Jones, Jenah; Jang, Il-Yong; Goldberg, Kenneth A.; Mochi, Iacopo; Marokkey, Sajan; Demmerle, Wolfgang; Pistor, Thomas V.; Denbeaux, Gregory

    2015-03-01

    The availability of defect-free masks is considered to be a critical issue for enabling extreme ultraviolet lithography (EUVL) as the next generation technology. Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the printability of the native EUV mask defects. In this work, we performed a systematic study of native mask defects to understand the defect printability caused by them. The multilayer growth over native substrate mask blank defects was correlated to the multilayer growth over regular-shaped defects having similar profiles in terms of their width and height. To model the multilayer growth over the defects, a novel level-set multilayer growth model was used that took into account the tool deposition conditions of the Veeco Nexus ion beam deposition tool. The same tool was used for performing the actual deposition of the multilayer stack over the characterized native defects, thus ensuring a fair comparison between the actual multilayer growth over native defects, and modeled multilayer growth over regular-shaped defects. Further, the printability of the characterized native defects was studied with the SEMATECH-Berkeley Actinic Inspection Tool (AIT), an EUV mask-imaging microscope at Lawrence Berkeley National Laboratory (LBNL). Printability of the modeled regular-shaped defects, which were propagated up the multilayer stack using level-set growth model was studied using defect printability simulations implementing the waveguide algorithm. Good comparison was observed between AIT and the simulation results, thus demonstrating that multilayer growth over a defect is primarily a function of a defect's width and height, irrespective of its shape. This would allow us to predict printability of the arbitrarily-shaped native EUV mask defects in a systematic and robust manner.

  2. Evaluating Printability of Buried Native EUV Mask Phase Defects through a Modeling and Simulation Approach

    SciTech Connect

    Upadhyaya, Mihir; Jindal, Vibhu; Basavalingappa, Adarsh; Herbol, Henry; Harris-Jones, Jenah; Jang, Il-Yong; Goldberg, Kenneth A.; Mochi, Iacopo; Marokkey, Sajan; Demmerle, Wolfgang; Pistor, Thomas V.; Denbeaux, Gregory

    2015-03-16

    The availability of defect-free masks is considered to be a critical issue for enabling extreme ultraviolet lithography (EUVL) as the next generation technology. Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the printability of the native EUV mask defects. In this work, we performed a systematic study of native mask defects to understand the defect printability caused by them. The multilayer growth over native substrate mask blank defects was correlated to the multilayer growth over regular-shaped defects having similar profiles in terms of their width and height. To model the multilayer growth over the defects, a novel level-set multilayer growth model was used that took into account the tool deposition conditions of the Veeco Nexus ion beam deposition tool. The same tool was used for performing the actual deposition of the multilayer stack over the characterized native defects, thus ensuring a fair comparison between the actual multilayer growth over native defects, and modeled multilayer growth over regular-shaped defects. Further, the printability of the characterized native defects was studied with the SEMATECH-Berkeley Actinic Inspection Tool (AIT), an EUV mask-imaging microscope at Lawrence Berkeley National Laboratory (LBNL). Printability of the modeled regular-shaped defects, which were propagated up the multilayer stack using level-set growth model was studied using defect printability simulations implementing the waveguide algorithm. Good comparison was observed between AIT and the simulation results, thus demonstrating that multilayer growth over a defect is primarily a function of a defect’s width and height, irrespective of its shape. This would allow us to predict printability of the arbitrarily-shaped native EUV mask defects in a systematic and robust manner.

  3. Predicting wafer-level IP error due to particle-induced EUVL reticle distortion during exposure chucking

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Vasu; Mikkelson, Andrew; Engelstad, Roxann; Lovell, Edward

    2005-11-01

    The mechanical distortion of an EUVL mask from mounting in an exposure tool can be a significant source of wafer-level image placement error. In particular, the presence of debris lodged between the reticle and chuck can cause the mask to experience out-of-plane distortion and in-plane distortion. A thorough understanding of the response of the reticle/particle/chuck system during electrostatic chucking is necessary to predict the resulting effects of such particle contamination on image placement accuracy. In this research, finite element modeling is employed to simulate this response for typical clamping conditions.

  4. A model of visual backward masking.

    PubMed

    Bugmann, Guido; Taylor, John G

    2005-01-01

    When two successive stimuli are presented within 0-200 ms intervals, the recognition of the first stimulus (the target) can be impaired by the second (the mask). This backward masking phenomenon has a form called metacontrast masking where the target and the mask are in close spatial proximity but not overlapping. In that case, the masking effect is strongest for interval of 60-100 ms. To understand this behaviour, activity propagation in a feedforward network of leaky integrate and fire neurons is investigated. It is found that, if neurons have a selectivity similar to that of V1 simple cells, activity decays layer after layer and ceases to propagate. To combat this, a local amplification mechanism is included in the model, using excitatory lateral connections, which turn out to support prolonged self-sustained activity. Masking is assumed to arise from local competition between representations recruited by the target and the mask. This tends to interrupt sustained firing, while prolonged retinal input tends to re-initiate it. Thus, masking causes a maximal reduction of the duration of the cortical response to the target towards the end of the retinal response. This duration exhibits the typical U-shape of the masking curve. In this model, masking does not alter the propagation of the onset of the response to the target, thus preserving response reaction times and enabling unconscious priming phenomena. PMID:15649600

  5. 100-Picometer Interferometry for EUVL

    SciTech Connect

    Sommargren, G E; Phillion, D W; Johnson, M A; Nguyen, N O; Barty, A; Snell, F J; Dillon, D R; Bradsher, L S

    2002-03-18

    Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.

  6. Measuring and characterizing the nonflatness of EUVL reticles and electrostatic chucks

    NASA Astrophysics Data System (ADS)

    Engelstad, Roxann L.; Turner, Kevin T.; Nataraju, Madhura; Sohn, Jaewoong; Mikkelson, Andrew R.; Battula, Venkata Siva; Vukkadala, Pradeep; Zeuske, Jacob R.; Van Peski, Chris K.

    2007-10-01

    According to the International Technology Roadmap for Semiconductors, meeting the strict requirements on image placement errors in the sub-45-nm regime may be one of the most difficult challenges for the industry. For Extreme Ultraviolet Lithography (EUVL), the nonflatness of both the mask and chuck is critical as well, due to the nontelecentric illumination during exposure. To address this issue, SEMI Standards P37 and P40 have established the specifications on flatness for the EUVL mask substrate and electrostatic chuck. This study investigates the procedures for implementing the Standards when measuring and characterizing the shapes of these surfaces. Finite element simulations are used to demonstrate the difficulties in supporting the mask substrate, while ensuring that the measured flatness is accurate. Additional modeling is performed to illustrate the most appropriate methods of characterizing the nonflatness of the electrostatic chuck. The results presented will aid in identifying modifications and clarifications that are needed in the Standards to facilitate the timely development of EUV lithography.

  7. Simplified models for mask roughness induced LER

    SciTech Connect

    McClinton, Brittany; Naulleau, Patrick

    2011-02-21

    The ITRS requires < 1.2nm line-edge roughness (LER) for the 22nm half-pitch node. Currently, we can consistently achieve only about 3nm LER. Further progress requires understanding the principle causes of LER. Much work has already been done on how both the resist and LER on the mask effect the final printed LER. What is poorly understood, however, is the extent to which system-level effects such as mask surface roughness, illumination conditions, and defocus couple to speckle at the image plane, and factor into LER limits. Presently, mask-roughness induced LER is studied via full 2D aerial image modeling and subsequent analysis of the resulting image. This method is time consuming and cumbersome. It is, therefore, the goal of this research to develop a useful 'rule-of-thumb' analytic model for mask roughness induced LER to expedite learning and understanding.

  8. An automated image-based tool for pupil plane characterization of EUVL tools

    NASA Astrophysics Data System (ADS)

    Levinson, Zac; Smith, Jack S.; Fenger, Germain; Smith, Bruce W.

    2016-03-01

    Pupil plane characterization will play a critical role in image process optimization for EUV lithography (EUVL), as it has for several lithography generations. In EUVL systems there is additional importance placed on understanding the ways that thermally-induced system drift affect pupil variation during operation. In-situ full pupil characterization is therefore essential for these tools. To this end we have developed Quick Inverse Pupil (QUIP)—a software suite developed for rapid characterization of pupil plane behavior based on images formed by that system. The software consists of three main components: 1) an image viewer, 2) the model builder, and 3) the wavefront analyzer. The image viewer analyzes CDSEM micrographs or actinic mask micrographs to measure either CDs or through-focus intensity volumes. The software is capable of rotation correction and image registration with subpixel accuracy. The second component pre-builds a model for a particular imaging system to enable rapid pupil characterization. Finally, the third component analyzes the results from the image viewer and uses the optional pre-built model for inverse solutions of pupil plane behavior. Both pupil amplitude and phase variation can be extracted using this software. Inverse solutions are obtained through a model based algorithm which is built on top of commercial rigorous full-vector simulation software.

  9. SEMATECH's EUV program: a key enabler for EUVL introduction

    NASA Astrophysics Data System (ADS)

    Wurm, Stefan; Jeon, Chan-Uk; Lercel, Michael

    2007-03-01

    With the introduction of alpha tools, extreme ultraviolet lithography (EUVL) has reached a key milestone. Users of those tools must have access to critical EUV infrastructure capabilities to evaluate the technology in a pilot line operation. In cooperation with universities, national laboratories, suppliers, integrated device manufacturers, and other industry consortia, SEMATECH has been spearheading the worldwide effort to develop this EUV infrastructure in the source, mask, optics, and resist areas. In the process, SEMATECH's Mask Blank Development Center, its EUV Resist Test Center, and the EUV expertise built within the SEMATECH EUV program have become key enablers for the successful introduction of EUV technology. We will highlight the significant contributions that the SEMATECH EUV Program has made, and continues to make, to the worldwide EUV infrastructure development effort. Moving beyond the alpha tool phase, the industry must have a clear understanding of the challenges that need to be addressed before EUV beta tools can be successfully introduced as early as 2009. We will identify those areas that still need a substantial effort to overcome technical and business challenges to meet 32 nm half-pitch requirements in time. Although some of those areas are clearly EUV-specific, others are generic and impact other lithography technologies as well. One of the major attractions of EUVL is that it is an extendible technology that can likely support patterning for several technology generations. We will review the outlook for EUVL technology extendibility and discuss what the industry needs to start working on to enable EUVL's bright future and long lifetime.

  10. Are Masking-Based Models of Risk Useful?

    PubMed

    Gisiner, Robert C

    2016-01-01

    As our understanding of directly observable effects from anthropogenic sound exposure has improved, concern about "unobservable" effects such as stress and masking have received greater attention. Equal energy models of masking such as power spectrum models have the appeal of simplicity, but do they offer biologically realistic assessments of the risk of masking? Data relevant to masking such as critical ratios, critical bandwidths, temporal resolution, and directional resolution along with what is known about general mammalian antimasking mechanisms all argue for a much more complicated view of masking when making decisions about the risk of masking inherent in a given anthropogenic sound exposure scenario. PMID:26610979

  11. Automated mask creation from a 3D model using Faethm.

    SciTech Connect

    Schiek, Richard Louis; Schmidt, Rodney Cannon

    2007-11-01

    We have developed and implemented a method which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micro-machining. The masks produced by this design tool can be generic, process independent masks, or if given process constraints, specific for a target process. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology of the model.

  12. Mask technology for EUV lithography

    NASA Astrophysics Data System (ADS)

    Bujak, M.; Burkhart, Scott C.; Cerjan, Charles J.; Kearney, Patrick A.; Moore, Craig E.; Prisbrey, Shon T.; Sweeney, Donald W.; Tong, William M.; Vernon, Stephen P.; Walton, Christopher C.; Warrick, Abbie L.; Weber, Frank J.; Wedowski, Marco; Wilhelmsen, Karl C.; Bokor, Jeffrey; Jeong, Sungho; Cardinale, Gregory F.; Ray-Chaudhuri, Avijit K.; Stivers, Alan R.; Tejnil, Edita; Yan, Pei-yang; Hector, Scott D.; Nguyen, Khanh B.

    1999-04-01

    Extreme UV Lithography (EUVL) is one of the leading candidates for the next generation lithography, which will decrease critical feature size to below 100 nm within 5 years. EUVL uses 10-14 nm light as envisioned by the EUV Limited Liability Company, a consortium formed by Intel and supported by Motorola and AMD to perform R and D work at three national laboratories. Much work has already taken place, with the first prototypical cameras operational at 13.4 nm using low energy laser plasma EUV light sources to investigate issues including the source, camera, electro- mechanical and system issues, photoresists, and of course the masks. EUV lithograph masks are fundamentally different than conventional photolithographic masks as they are reflective instead of transmissive. EUV light at 13.4 nm is rapidly absorbed by most materials, thus all light transmission within the EUVL system from source to silicon wafer, including EUV reflected from the mask, is performed by multilayer mirrors in vacuum.

  13. Extreme Ultraviolet Lithography - Reflective Mask Technology

    SciTech Connect

    Walton, C.C.; Kearney, P.A.; Mirkarimi, P.B.; Bowers, J.M.; Cerjan, C.; Warrick, A.L.; Wilhelmsen, K.; Fought, E.; Moore, C.; Larson, C.; Baker, S.; Burkhart, S.C.; Hector, S.D.

    2000-05-09

    EUVL mask blanks consist of a distributed Bragg reflector made of 6.7nm-pitch bi-layers of MO and Si deposited upon a precision Si or glass substrate. The layer deposition process has been optimized for low defects, by application of a vendor-supplied but highly modified ion-beam sputter deposition system. This system is fully automated using SMIF technology to obtain the lowest possible environmental- and handling-added defect levels. Originally designed to coat 150mm substrates, it was upgraded in July, 1999 to 200 mm and has coated runs of over 50 substrates at a time with median added defects >100nm below 0.05/cm{sup 2}. These improvements have resulted from a number of ion-beam sputter deposition system modifications, upgrades, and operational changes, which will be discussed. Success in defect reduction is highly dependent upon defect detection, characterization, and cross-platform positional registration. We have made significant progress in adapting and extending commercial tools to this purpose, and have identified the surface scanner detection limits for different defect classes, and the signatures of false counts and non-printable scattering anomalies on the mask blank. We will present key results and how they have helped reduce added defects. The physics of defect reduction and mitigation is being investigated by a program on multilayer growth over deliberately placed perturbations (defects) of varying size. This program includes modeling of multilayer growth and modeling of defect printability. We developed a technique for depositing uniformly sized gold spheres on EUVL substrates, and have studied the suppression of the perturbations during multilayer growth under varying conditions. This work is key to determining the lower limit of critical defect size for EUV Lithography. We present key aspects of this work. We will summarize progress in all aspects of EUVL mask blank development, and present detailed results on defect reduction and mask blank

  14. Attentional gating models of object substitution masking.

    PubMed

    Põder, Endel

    2013-11-01

    Di Lollo, Enns, and Rensink (2000) proposed the computational model of object substitution (CMOS) to explain their experimental results with sparse visual maskers. This model supposedly is based on reentrant hypotheses testing in the visual system, and the modeled experiments are believed to demonstrate these reentrant processes in human vision. In this study, I analyze the main assumptions of this model. I argue that CMOS is a version of the attentional gating model and that its relationship with reentrant processing is rather illusory. The fit of this model to the data indicates that reentrant hypotheses testing is not necessary for the explanation of object substitution masking (OSM). Further, the original CMOS cannot predict some important aspects of the experimental data. I test 2 new models incorporating an unselective processing (divided attention) stage; these models are more consistent with data from OSM experiments. My modeling shows that the apparent complexity of OSM can be reduced to a few simple and well-known mechanisms of perception and memory. PMID:23106303

  15. Modeling Spatial and Temporal Aspects of Visual Backward Masking

    ERIC Educational Resources Information Center

    Hermens, Frouke; Luksys, Gediminas; Gerstner, Wulfram; Herzog, Michael H.; Ernst, Udo

    2008-01-01

    Visual backward masking is a versatile tool for understanding principles and limitations of visual information processing in the human brain. However, the mechanisms underlying masking are still poorly understood. In the current contribution, the authors show that a structurally simple mathematical model can explain many spatial and temporal…

  16. Thermomechanical global response of the EUVL wafer during exposure

    NASA Astrophysics Data System (ADS)

    Chang, Jaehyuk; Martin, Carl J.; Engelstad, Roxann L.; Lovell, Edward G.

    2002-07-01

    Extreme ultraviolet lithography (EUVL) is one of the leading technologies for Next-Generation Lithography. Continued progress in its development will be facilitated by characterizing all sources of distortion in the chip fabrication process. These include the thermal distortions of the wafer caused by deposited EUVL energy during scanning exposure. Absorbed energy from the beam produces temperature increases and structural displacements in the wafer, which directly contribute to pattern placement errors and image blur. Because of the vacuum conditions of EUVL systems, wafer chucking will be electrostatic, which has a number of advantages over mechanical clamping systems. The goals of this research are to predict the transient temperature increases and corresponding displacements (locally and globally) consistent with the thermomechanical boundary conditions of the wafer. Both thermal and structural finite element models were constructed to numerically simulate wafer exposure. The response of the wafer is relatively sensitive to the interface conditions between the substrate and electrostatic chuck. Thus, parametric studies of the response to changes in the contact conductance and the friction coefficient were performed and are presented in this paper.

  17. Optimization of electrostatic chuck for mask-blank flatness control in extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Shu, Emily Y.

    2007-05-01

    Overlay requirements of Extreme Ultra-violet Lithography (EUVL) dictate reticle flatness errors of 50nm or less. During the early phase of EUVL development, it was decided that an electrostatic chuck was required to flatten EUVL masks to these specifications. However current experience and test data have demonstrated that it will be very difficult to reach the desired mask flatness goal without a thorough understanding and advanced control of the echucking process. The results of a parametric model study are reported in this paper. In this study we calculated the chucking force dependence of activating voltage, e-chuck geometry, film material, and pin design, and then proposed an optimized chuck design. We have also engaged in a material study for the mask backside coating for the purpose of reducing flatness errors and minimizing backside particle generation. We have also designed and built an automated, vacuum based, interferometric metrology tool to enable e-chucking experimentation. An early status report of this tool will be included in this paper.

  18. Diffraction modelling of laser ablation using transmission masks

    NASA Astrophysics Data System (ADS)

    Dyer, P. E.; Mackay, J.; Walton, C. D.

    2004-10-01

    We present an analysis of near-field diffraction effects in ablation with transmission masks, based on coupling a simplified form of the Fresnel-Kirchhoff diffraction integral with basic models for material removal. Modelling for square, hexagonal and circular proximity masks is described and compared with previously reported experiments on glass, silicon and polyimide using excimer, femtosecond and CO2 lasers. The model has general applicability and can provide useful insight into the effect of near-field diffraction in ablation patterning.

  19. Masked Areas in Shear Peak Statistics: A Forward Modeling Approach

    NASA Astrophysics Data System (ADS)

    Bard, D.; Kratochvil, J. M.; Dawson, W.

    2016-03-01

    The statistics of shear peaks have been shown to provide valuable cosmological information beyond the power spectrum, and will be an important constraint of models of cosmology in forthcoming astronomical surveys. Surveys include masked areas due to bright stars, bad pixels etc., which must be accounted for in producing constraints on cosmology from shear maps. We advocate a forward-modeling approach, where the impacts of masking and other survey artifacts are accounted for in the theoretical prediction of cosmological parameters, rather than correcting survey data to remove them. We use masks based on the Deep Lens Survey, and explore the impact of up to 37% of the survey area being masked on LSST and DES-scale surveys. By reconstructing maps of aperture mass the masking effect is smoothed out, resulting in up to 14% smaller statistical uncertainties compared to simply reducing the survey area by the masked area. We show that, even in the presence of large survey masks, the bias in cosmological parameter estimation produced in the forward-modeling process is ≈1%, dominated by bias caused by limited simulation volume. We also explore how this potential bias scales with survey area and evaluate how much small survey areas are impacted by the differences in cosmological structure in the data and simulated volumes, due to cosmic variance.

  20. Masks for extreme ultraviolet lithography

    SciTech Connect

    Cardinale, G; Goldsmith, J; Kearney, P A; Larson, C; Moore, C E; Prisbrey, S; Tong, W; Vernon, S P; Weber, F; Yan, P-Y

    1998-09-01

    In extreme ultraviolet lithography (EUVL), the technology specific requirements on the mask are a direct consequence of the utilization of radiation in the spectral region between 10 and 15 nm. At these wavelengths, all condensed materials are highly absorbing and efficient radiation transport mandates the use of all-reflective optical systems. Reflectivity is achieved with resonant, wavelength-matched multilayer (ML) coatings on all of the optical surfaces - including the mask. The EUV mask has a unique architecture - it consists of a substrate with a highly reflective ML coating (the mask blank) that is subsequently over-coated with a patterned absorber layer (the mask). Particulate contamination on the EUVL mask surface, errors in absorber definition and defects in the ML coating all have the potential to print in the lithographic process. While highly developed technologies exist for repair of the absorber layer, no viable strategy for the repair of ML coating defects has been identified. In this paper the state-of-the-art in ML deposition technology, optical inspection of EUVL mask blank defects and candidate absorber patterning approaches are reviewed.

  1. On-line simulations of models for backward masking.

    PubMed

    Francis, Gregory

    2003-11-01

    Five simulations of quantitative models of visual backward masking are available on the Internet at http://www.psych.purdue.edu/-gfrancis/Publications/BackwardMasking/. The simulations can be run in a Web browser that supports the Java programming language. This article describes the motivation for making the simulations available and gives a brief introduction as to how the simulations are used. The source code is available on the Web page, and this article describes how the code is organized. PMID:14748495

  2. Model of visual contrast gain control and pattern masking

    NASA Technical Reports Server (NTRS)

    Watson, A. B.; Solomon, J. A.

    1997-01-01

    We have implemented a model of contrast gain and control in human vision that incorporates a number of key features, including a contrast sensitivity function, multiple oriented bandpass channels, accelerating nonlinearities, and a devisive inhibitory gain control pool. The parameters of this model have been optimized through a fit to the recent data that describe masking of a Gabor function by cosine and Gabor masks [J. M. Foley, "Human luminance pattern mechanisms: masking experiments require a new model," J. Opt. Soc. Am. A 11, 1710 (1994)]. The model achieves a good fit to the data. We also demonstrate how the concept of recruitment may accommodate a variant of this model in which excitatory and inhibitory paths have a common accelerating nonlinearity, but which include multiple channels tuned to different levels of contrast.

  3. The difficult business model for mask equipment makers and mask infrastructure development support from consortia and governments

    NASA Astrophysics Data System (ADS)

    Hector, Scott

    2005-11-01

    The extension of optical projection lithography through immersion to patterning features with half pitch <=65 nm is placing greater demands on the mask. Strong resolution enhancement techniques (RETs), such as embedded and alternating phase shift masks and complex model-based optical proximity correction, are required to compensate for diffraction and limited depth of focus (DOF). To fabricate these masks, many new or upgraded tools are required to write patterns, measure feature sizes and placement, inspect for defects, review defect printability and repair defects on these masks. Beyond the significant technical challenges, suppliers of mask fabrication equipment face the challenge of being profitable in the small market for mask equipment while encountering significant R&D expenses to bring new generations of mask fabrication equipment to market. The total available market for patterned masks is estimated to be $2.5B to $2.9B per year. The patterned mask market is about 20% of the market size for lithography equipment and materials. The total available market for mask-making equipment is estimated to be about $800M per year. The largest R&D affordability issue arises for the makers of equipment for fabricating masks where total available sales are typically less than ten units per year. SEMATECH has used discounted cash flow models to predict the affordable R&D while maintaining industry accepted internal rates of return. The results have been compared to estimates of the total R&D cost to bring a new generation of mask equipment to market for various types of tools. The analysis revealed that affordability of the required R&D is a significant problem for many suppliers of mask-making equipment. Consortia such as SEMATECH and Selete have played an important role in cost sharing selected mask equipment and material development projects. Governments in the United States, in Europe and in Japan have also helped equipment suppliers with support for R&D. This paper

  4. Evaluation of a new model of mask topography effects

    NASA Astrophysics Data System (ADS)

    Pierrat, Christophe

    2010-09-01

    A new method for simulating mask topography effects is described. A model comprising a set of functions is generated based on the results of test patterns simulated using rigorous mask simulation. The functions are combined with the thin mask diffraction pattern in order to create a modeled thick mask diffraction pattern. The mask diffraction pattern is subsequently used in the lithosimTM simulation tool to generate the wafer image. Results are described for 1D and 2D test structures. The 1D test structures is a line and space test pattern where the line is set at 40nm width and the space is varied from 40nm to 1000nm. The illumination setting chosen was a TE polarized dipole illumination with a pole distance of 0.9 and a pole radius of 0.01. First the accuracy of the simulator itself was verified using thin mask calculation and comparing the data to another simulator. The intensity profiles are virtually identical. The RMS of the difference between the two plots is 8E-05. Next the model is compared to the rigorous calculation. The RMS of the difference between the two plots is 3E-03. The standard deviation of the CD difference between the model and the rigorous calculation, calculated for 5 thresholds (0.1, 0.11, 0.12, 0.13, and 0.14) and for all the structures, is 0.38nm. We also demonstrate that the mask model can be used with different optical settings by showing an example of two additional defocus values with an identical RMS of 3E-03. For the 2D test pattern made of a dense contact array, the mask fields are computed using rigorous calculation and compared to the model. The difference between the fields is within the error of the rigorous calculation. The resulting wafer images are almost identical. No re-scaling of the data was applied to either the mask fields or the wafer images.

  5. Mask roughness induced LER: geometric model at long correlation lengths

    SciTech Connect

    McClinton, Brittany M.; Naulleau, Patrick P.

    2011-02-11

    Collective understanding of how both the resist and line-edge roughness (LER) on the mask affect the final printed LER has made significant advances. What is poorly understood, however, is the extent to which mask surface roughness couples to image plane LER as a function of illumination conditions, NA, and defocus. Recently, progress has been made in formulating a simplified solution for mask roughness induced LER. Here, we investigate the LER behavior at long correlation lengths of surface roughness on the mask. We find that for correlation lengths greater than 3/NA in wafer dimensions and CDs greater than approximately 0.75/NA, the previously described simplified model, which remains based on physical optics, converges to a 'geometric regime' which is based on ray optics and is independent of partial coherence. In this 'geometric regime', the LER is proportional to the mask slope error as it propagates through focus, and provides a faster alternative to calculating LER in contrast to either full 2D aerial image simulation modeling or the newly proposed physical optics model. Data is presented for both an NA = 0.32 and an NA = 0.5 imaging system for CDs of 22-nm and 50-nm horizontal-line-dense structures.

  6. Low-defect reflective mask blanks for extreme ultraviolet lithography

    SciTech Connect

    Burkhart, S C; Cerjarn, C; Kearney, P; Mirkarimi, P; Walton, C; Ray-Chaudhuri, A

    1999-03-11

    Extreme Ultraviolet Lithgraphy (EUVL) is an emerging technology for fabrication of sub-100 nm feature sizes on silicon, following the SIA roadmap well into the 21st century. The specific EUVL system described is a scanned, projection lithography system with a 4:1 reduction, using a laser plasma EUV source. The mask and all of the system optics are reflective, multilayer mirrors which function in the extreme ultraviolet at 13.4 nm wavelength. Since the masks are imaged to the wafer exposure plane, mask defects greater than 80% of the exposure plane CD (for 4:1 reduction) will in many cases render the mask useless, whereas intervening optics can have defects which are not a printing problem. For the 100 nm node, we must reduce defects to less than 0.01/cm² @ 80nm or larger to obtain acceptable mask production yields. We have succeeded in reducing the defects to less than 0.1/cm² for defects larger than 130 nm detected by visible light inspection tools, however our program goal is to achieve 0.01/cm² in the near future. More importantly though, we plan to have a detailed understanding of defect origination and the effect on multilayer growth in order to mitigate defects below the 10-2/cm² level on the next generation of mask blank deposition systems. In this paper we will discuss issues and results from the ion-beam multilayer deposition tool, details of the defect detection and characterization facility, and progress on defect printability modeling.

  7. A model of selective masking in chromatic detection.

    PubMed

    Shepard, Timothy G; Swanson, Emily A; McCarthy, Comfrey L; Eskew, Rhea T

    2016-07-01

    Narrowly tuned, selective noise masking of chromatic detection has been taken as evidence for the existence of a large number of color mechanisms (i.e., higher order color mechanisms). Here we replicate earlier observations of selective masking of tests in the (L,M) plane of cone space when the noise is placed near the corners of the detection contour. We used unipolar Gaussian blob tests with three different noise color directions, and we show that there are substantial asymmetries in the detection contours-asymmetries that would have been missed with bipolar tests such as Gabor patches. We develop a new chromatic detection model, which is based on probability summation of linear cone combinations, and incorporates a linear contrast energy versus noise power relationship that predicts how the sensitivity of these mechanisms changes with noise contrast and chromaticity. With only six unipolar color mechanisms (the same number as the cardinal model), the new model accounts for the threshold contours across the different noise conditions, including the asymmetries and the selective effects of the noises. The key for producing selective noise masking in the (L,M) plane is having more than two mechanisms with opposed L- and M-cone inputs, in which case selective masking can be produced without large numbers of color mechanisms. PMID:27442723

  8. Extreme ultraviolet lithography mask etch study and overview

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    An overview of extreme ultraviolet lithography (EUVL) mask etch is presented and a EUVL mask etch study was carried out. Today, EUVL implementation has three critical challenges that hinder its adoption: extreme ultraviolet (EUV) source power, resist resolution-line width roughness-sensitivity, and a qualified EUVL mask. The EUVL mask defect challenges result from defects generated during blank preparation, absorber and multilayer deposition processes, as well as patterning, etching and wet clean processes. Stringent control on several performance criteria including critical dimension (CD) uniformity, etch bias, micro-loading, profile control, defect control, and high etch selectivity requirement to capping layer is required during the resist pattern duplication on the underlying absorber layer. EUVL mask absorbers comprise of mainly tantalum-based materials rather than chrome- or MoSi-based materials used in standard optical masks. Compared to the conventional chrome-based absorbers and phase shift materials, tantalum-based absorbers need high ion energy to obtain moderate etch rates. However, high ion energy may lower resist selectivity, and could introduce defects. Current EUVL mask consists of an anti-reflective layer on top of the bulk absorber. Recent studies indicate that a native oxide layer would suffice as an anti-reflective coating layer during the electron beam inspection. The absorber thickness and the material properties are optimized based on optical density targets for the mask as well as electromagnetic field effects and optics requirements of the patterning tools. EUVL mask etch processes are modified according to the structure of the absorber, its material, and thickness. However, etch product volatility is the fundamental requirement. Overlapping lithographic exposure near chip border may require etching through the multilayer, resulting in challenges in profile control and etch selectivity. Optical proximity correction is applied to further

  9. Phase-induced amplitude apodization complex mask coronagraph mask fabrication, characterization, and modeling for WFIRST-AFTA

    NASA Astrophysics Data System (ADS)

    Kern, Brian; Guyon, Olivier; Belikov, Ruslan; Wilson, Daniel; Muller, Richard; Sidick, Erkin; Balasubramanian, Bala; Krist, John; Poberezhskiy, Ilya; Tang, Hong

    2016-01-01

    This work describes the fabrication, characterization, and modeling of a second-generation occulting mask for a phase-induced amplitude apodization complex mask coronagraph, designed for use on the WFIRST-AFTA mission. The mask has many small features (˜micron lateral scales) and was fabricated at the Jet Propulsion Laboratory Microdevices Laboratory, then characterized using a scanning electron microscope, atomic force microscope, and optical interferometric microscope. The measured fabrication errors were then fed to a wavefront control model which predicts the contrast performance of a full coronagraph. The expected coronagraphic performance using this mask is consistent with observing ˜15 planetary targets with WFIRST-AFTA in a reasonable time (<1 day/target).

  10. System for generating two-dimensional masks from a three-dimensional model using topological analysis

    DOEpatents

    Schiek, Richard

    2006-06-20

    A method of generating two-dimensional masks from a three-dimensional model comprises providing a three-dimensional model representing a micro-electro-mechanical structure for manufacture and a description of process mask requirements, reducing the three-dimensional model to a topological description of unique cross sections, and selecting candidate masks from the unique cross sections and the cross section topology. The method further can comprise reconciling the candidate masks based on the process mask requirements description to produce two-dimensional process masks.

  11. Analysis of the mechanical response of extreme ultraviolet lithography masks during electrostatic chucking

    NASA Astrophysics Data System (ADS)

    Nataraju, Madhura

    Stringent flatness requirements have been imposed for the front and back surfaces of Extreme Ultraviolet Lithography (EUVL) masks to ensure successful pattern transfer that satisfies the image placement error budget. During exposure an electrostatic chuck will be used to support and flatten the mask. The EUVL Mask and Chucking Standards, SEMI P-37 and SEMI P-40, specify the flatness of the two mask surfaces as well as the chucking surface to be within about 50 nm peak-to-valley. It is critical that the electrostatic chucking process and its effect on mask flatness be well-understood. The principal objective of this thesis is to develop a model that predicts the electrostatic chucking response of masks and the resulting flatness of the pattern surface using FE techniques and to validate this model with chucking experiments. Studies are performed to evaluate the definition of flatness as given in the SEMI standards and a more efficient representation is suggested. Classical plate theory is used to illustrate the effect of chuck thickness and stiffness on the chucking response of masks. A basic FE model is developed to demonstrate that the sum of the chuck shape and thickness variation of the mask are crucial to the response of the mask during chucking. FE models are also developed to model clamping using a bipolar Coulombic pin chuck used for this research. The initial geometry of the mask and chuck surfaces are created using interferometric flatness data. Chucking is simulated by the application of forces between the mask backside and the chuck surface. The final pattern surface shape is compared with experimental electrostatic chucking results. An experimental set-up is developed to validate the FE model predictions. This consists of a Zygo interferometer mounted on top of an optical table, inside a cleanroom, with the chuck and mask placed inside a vacuum chamber. Once the voltage is turned on, the pattern surface nonflatness is measured using the interferometer

  12. Mask process matching using a model based data preparation solution

    NASA Astrophysics Data System (ADS)

    Dillon, Brian; Saib, Mohamed; Figueiro, Thiago; Petroni, Paolo; Progler, Chris; Schiavone, Patrick

    2015-10-01

    Process matching is the ability to precisely reproduce the signature of a given fabrication process while using a different one. A process signature is typically described as systematic CD variation driven by feature geometry as a function of feature size, local density or distance to neighboring structures. The interest of performing process matching is usually to address differences in the mask fabrication process without altering the signature of the mask, which is already validated by OPC models and already used in production. The need for such process matching typically arises from the expansion of the production capacity within the same or different mask fabrication facilities, from the introduction of new, perhaps more advanced, equipment to deliver same process of record masks and/or from the re-alignment of processes which have altered over time. For state-of-the-art logic and memory mask processes, such matching requirements can be well below 2nm and are expected to reduce below 1nm in near future. In this paper, a data preparation solution for process matching is presented and discussed. Instead of adapting the physical process itself, a calibrated model is used to modify the data to be exposed by the source process in order to induce the results to match the one obtained while running the target process. This strategy consists in using the differences among measurements from the source and target processes, in the calibration of a single differential model. In this approach, no information other than the metrology results is required from either process. Experimental results were obtained by matching two different processes at Photronics. The standard deviation between both processes was of 2.4nm. After applying the process matching technique, the average absolute difference between the processes was reduced to 1.0nm with a standard deviation of 1.3nm. The methods used to achieve the result will be described along with implementation considerations, to

  13. EUV mask and chuck analysis: simulation and experimentation

    NASA Astrophysics Data System (ADS)

    Nataraju, Madhura; Sohn, Jaewoong; Mikkelson, Andrew R.; Turner, Kevin T.; Engelstad, Roxann L.; Van Peski, Chris K.

    2006-03-01

    Extreme ultraviolet (EUV) masks and mask chucks require extreme flatness in order to meet the performance and timing specified by the International Technology Roadmap for Semiconductors (ITRS). The EUVL Mask and Chucking Standards, SEMI P37 and SEMI P40, specify the nonflatness of the mask frontside and backside, as well as the chucking surface, to be no more than 50 nm peak-to-valley (p-v). Understanding and characterizing the clamping ability of the electrostatic chuck and its effect on the mask flatness is a critical issue. In the present study, chucking experiments were performed using an electrostatic pin chuck and finite element (FE) models were developed to simulate the chucking. The frontside and backside surface flatness of several EUV substrates were measured using a Zygo large-area interferometer. Flatness data for the electrostatic chuck was also obtained and this data along with the substrate flatness data was used as the input for the FE modeling. Data from one substrate was selected for modeling and testing and is included in this paper. Electrostatic chucking experiments were conducted in a clean-room facility to minimize contamination due to particles. The substrate was chucked using an electrostatic pin chuck and the measured flatness was compared to the predictions obtained from the FE simulation.

  14. Calibration of a Spatial-Temporal Discrimination Model from Forward, Simultaneous, and Backward Masking

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J.; Beard, B. L.; Stone, Leland (Technical Monitor)

    1997-01-01

    We have been developing a simplified spatial-temporal discrimination model similar to our simplified spatial model in that masking is assumed to be a function of the local visible contrast energy. The overall spatial-temporal sensitivity of the model is calibrated to predict the detectability of targets on a uniform background. To calibrate the spatial-temporal integration functions that define local visible contrast energy, spatial-temporal masking data are required. Observer thresholds were measured (2IFC) for the detection of a 12 msec target stimulus in the presence of a 700 msec mask. Targets were 1, 3 or 9 c/deg sine wave gratings. Masks were either one of these gratings or two of them combined. The target was presented in 17 temporal positions with respect to the mask, including positions before, during and after the mask. Peak masking was found near mask onset and offset for 1 and 3 c/deg targets, while masking effects were more nearly uniform during the mask for the 9 c/deg target. As in the purely spatial case, the simplified model can not predict all the details of masking as a function of masking component spatial frequencies, but overall the prediction errors are small.

  15. Patterned mask inspection technology with Projection Electron Microscope (PEM) technique for 11 nm half-pitch (hp) generation EUV masks

    NASA Astrophysics Data System (ADS)

    Hirano, Ryoichi; Iida, Susumu; Amano, Tsuyoshi; Watanabe, Hidehiro; Hatakeyama, Masahiro; Murakami, Takeshi; Yoshikawa, Shoji; Suematsu, Kenichi; Terao, Kenji

    2015-07-01

    High-sensitivity EUV mask pattern defect detection is one of the major issues in order to realize the device fabrication by using the EUV lithography. We have already designed a novel Projection Electron Microscope (PEM) optics that has been integrated into a new inspection system named EBEYE-V30 ("Model EBEYE" is an EBARA's model code), and which seems to be quite promising for 16 nm hp generation EUVL Patterned mask Inspection (PI). Defect inspection sensitivity was evaluated by capturing an electron image generated at the mask by focusing onto an image sensor. The progress of the novel PEM optics performance is not only about making an image sensor with higher resolution but also about doing a better image processing to enhance the defect signal. In this paper, we describe the experimental results of EUV patterned mask inspection using the above-mentioned system. The performance of the system is measured in terms of defect detectability for 11 nm hp generation EUV mask. To improve the inspection throughput for 11 nm hp generation defect detection, it would require a data processing rate of greater than 1.5 Giga- Pixel-Per-Second (GPPS) that would realize less than eight hours of inspection time including the step-and-scan motion associated with the process. The aims of the development program are to attain a higher throughput, and enhance the defect detection sensitivity by using an adequate pixel size with sophisticated image processing resulting in a higher processing rate.

  16. Mask roughness induced LER control and mitigation: aberrations sensitivity study and alternate illumination scheme

    NASA Astrophysics Data System (ADS)

    McClinton, Brittany M.; Naulleau, Patrick P.

    2011-04-01

    Here we conduct a mask-roughness-induced line-edge-roughness (LER) aberrations sensitivity study both as a random distribution amongst the first 16 Fringe Zernikes (for overall aberration levels of 0.25, 0.50, and 0.75nm rms) as well as an individual aberrations sensitivity matrix over the first 37 Fringe Zernikes. Full 2D aerial image modeling for an imaging system with NA = 0.32 was done for both the 22-nm and 16-nm half-pitch nodes on a rough mask with a replicated surface roughness (RSR) of 100 pm and a correlation length of 32 nm at the nominal extreme-ultraviolet lithography (EUVL) wavelength of 13.5nm. As the ideal RSR value for commercialization of EUVL is 50 pm and under, and furthermore as has been shown elsewhere, a correlation length of 32 nm of roughness on the mask sits on the peak LER value for an NA = 0.32 imaging optic, these mask roughness values and consequently the aberration sensitivity study presented here, represent a worst-case scenario. The illumination conditions were chosen based on the possible candidates for the 22-nm and 16-nm half-pitch nodes, respectively. In the 22-nm case, a disk illumination setting of σ = 0.50 was used, and for the 16-nm case, crosspole illumination with σ = 0.10 at an optimum offset of dx = 0 and dy = .67 in sigma space. In examining how to mitigate mask roughness induced LER, we considered an alternate illumination scheme whereby a traditional dipole's angular spectrum is extended in the direction parallel to the line-and-space mask absorber pattern to represent a "strip". While this illumination surprisingly provides minimal improvement to the LER as compared to several alternate illumination schemes, the overall imaging quality in terms of image-log-slope (ILS) and contrast is improved.

  17. Mask roughness induced LER control and mitigation: aberrations sensitivity study and alternate illumination scheme

    SciTech Connect

    McClinton, Brittany M.; Naulleau, Patrick P.

    2011-03-11

    Here we conduct a mask-roughness-induced line-edge-roughness (LER) aberrations sensitivity study both as a random distribution amongst the first 16 Fringe Zernikes (for overall aberration levels of 0.25, 0.50, and 0.75nm rms) as well as an individual aberrations sensitivity matrix over the first 37 Fringe Zernikes. Full 2D aerial image modeling for an imaging system with NA = 0.32 was done for both the 22-nm and 16-nm half-pitch nodes on a rough mask with a replicated surface roughness (RSR) of 100 pm and a correlation length of 32 nm at the nominal extreme-ultraviolet lithography (EUVL) wavelength of 13.5nm. As the ideal RSR value for commercialization of EUVL is 50 pm and under, and furthermore as has been shown elsewhere, a correlation length of 32 nm of roughness on the mask sits on the peak LER value for an NA = 0.32 imaging optic, these mask roughness values and consequently the aberration sensitivity study presented here, represent a worst-case scenario. The illumination conditions were chosen based on the possible candidates for the 22-nm and 16-nm half-pitch nodes, respectively. In the 22-nm case, a disk illumination setting of {sigma} = 0.50 was used, and for the 16-nm case, crosspole illumination with {sigma} = 0.10 at an optimum offset of dx = 0 and dy = .67 in sigma space. In examining how to mitigate mask roughness induced LER, we considered an alternate illumination scheme whereby a traditional dipole's angular spectrum is extended in the direction parallel to the line-and-space mask absorber pattern to represent a 'strip'. While this illumination surprisingly provides minimal improvement to the LER as compared to several alternate illumination schemes, the overall imaging quality in terms of image-log-slope (ILS) and contrast is improved.

  18. A patch-based cross masking model for natural images with detail loss and additive defects

    NASA Astrophysics Data System (ADS)

    Liu, Yucheng; Allebach, Jan P.

    2015-03-01

    Visual masking is an effect that contents of the image reduce the detectability of a given target signal hidden in the image. The effect of visual masking has found its application in numerous image processing and vision tasks. In the past few decades, numerous research has been conducted on visual masking based on models optimized for artificial targets placed upon unnatural masks. Over the years, there is a tendency to apply masking model to predict natural image quality and detection threshold of distortion presented in natural images. However, to our knowledge few studies have been conducted to understand the generalizability of masking model to different types of distortion presented in natural images. In this work, we measure the ability of natural image patches in masking three different types of distortion, and analyse the performance of conventional gain control model in predicting the distortion detection threshold. We then propose a new masking model, where detail loss and additive defects are modeled in two parallel vision channels and interact with each other via a cross masking mechanism. We show that the proposed cross masking model has better adaptability to various image structures and distortions in natural scenes.

  19. Techniques to measure force uniformity of electrostatic chucks for EUV mask clamping

    NASA Astrophysics Data System (ADS)

    Veeraraghavan, Sathish; Sohn, Jaewoong; Turner, Kevin T.

    2007-10-01

    Extreme ultraviolet lithography (EUVL) has stringent requirements on image placement (IP) errors in order to allow for the patterning of devices with critical dimensions (CD) in the sub-32 nm regime. A major contributor to IP error in EUVL is non-flatness of the mask. Electrostatic chucks are used to support and flatten masks in EUVL scanners. Proper operation requires that the electrostatic forces generated by the chuck be of sufficient magnitude and be uniform over the entire chucking area. Hence, there is a need to measure the clamping pressure distribution to properly characterize performance of electrostatic chucks. This paper discusses two methods to measure electrostatic pressure magnitude and uniformity by examining the distortion of thin substrates (wafers) during chucking. In the first method, a wafer with lithographically defined mesas is chucked with the mesas located at the interface between the wafer and the chuck and thus results in a void near the mesa after chucking. Analytical and finite element models were used to relate the resulting void radius to the electrostatic pressure and used to assess the feasibility of the technique. Measurements of pressure on a slab chuck were conducted to demonstrate the mesa measurement approach. The second measurement method examines the deflection of a wafer between pins on a pin chuck in order to estimate the local pressure. A 3D FE model was developed to predict the deformation of the wafer between the pins as a function of applied pressure. The model was used to assess the feasibility of the approach and provide guidance on selecting appropriate substrates for use in such experiments.

  20. Analysis of a relation between the spatial frequency of electrostatic chuck and induced mask inplane distortion (IPD)

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takeshi; Ota, Kazuya; Nishimura, Naosuke; Warisawa, Shin'ichi; Ishihara, Sunao

    2009-03-01

    Due to potential applications of Extreme Ultraviolet Lithography (EUVL) to 22 nm half-pitch (hp) generations, EUVL is well researched. However, current SEMI standards about the chuck are based on only the local slope of roughness. Herein chuck standards, which consider the spatial frequency of the chuck surface roughness as well as the local slope of the shape, are proposed by examining the chuck roughness. To prevent a mask pattern shift when an EUVL mask is clamped by an electrostatic chuck, the roughness height must be limited. Thus, the in-plane distortion (IPD) and out-of-plane distortion (OPD) are introduced to evaluate the mask pattern shift. This research utilizes ANSYS to evaluate the relationship between the spatial frequency of chuck roughness and IPD/OPD induced on the mask surface after an EUVL mask is clamped by the chuck. The IPD depends on the local slope of the surface roughness shape of the electrostatic chuck (ESC) as well as the spatial frequency of the roughness. Therefore, re-polishing the chuck surface can decrease IPD. Moreover, the spatial frequency of roughness must be considered when a mask pattern shift correction is performed according to the surface roughness shape of the EUVL mask and ESC.

  1. Mechanisms of Masked Priming: Testing the Entry Opening Model

    ERIC Educational Resources Information Center

    Wu, Hongmei

    2012-01-01

    Since it was introduced in Forster and Davis (1984), masked priming has been widely adopted in the psycholinguistic research on visual word recognition, but there has been little consensus on its actual mechanisms, i.e. how it occurs and how it should be interpreted. This dissertation addresses two different interpretations of masked priming, one…

  2. Modeling and Observations of Phase-Mask Trapezoidal Profiles with Grating-Fiber Image Reproduction

    NASA Technical Reports Server (NTRS)

    Lyons, Donald R.; Lindesay, James V.; Lee, Hyung R.; Ndlela, Zolili U.; Thompso, Erica J.

    2000-01-01

    We report on an investigation of the trapezoidal design and fabrication defects in phase masks used to produce Bragg reflection gratings in optical fibers. We used a direct visualization technique to examine the nonuniformity of the interference patterns generated by several phase masks. Fringe patterns from the phase masks are compared with the analogous patterns resulting from two-beam interference. Atomic force microscope imaging of the actual phase gratings that give rise to anomalous fringe patterns is used to determine input parameters for a general theoretical model. Phase masks with pitches of 0.566 and 1.059 microns are modeled and investigated.

  3. Automated surface micro-machining mask creation from a 3D model.

    SciTech Connect

    Schiek, Richard Louis; Schmidt, Rodney Cannon

    2004-06-01

    We have developed and implemented a method, which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micromachining. The masks produced by this design tool can be generic, process independent masks, or if given process constraints, specific for a target process. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology to the model. The 3D model is first separated into bodies that are non-intersecting, made from different materials or only linked through a ground plane. Next, for each body unique vertical cross sections are located and arranged into a tree based on their topological relationship. A branch-wise search of the tree uncovers locations where deposition boundaries must lie and identifies candidate masks creating a generic mask set for the 3D model. Finally, in the last step specific process requirements are considered that may constrain the generic mask set. Constraints can include the thickness or number of deposition layers, specific ordering of masks as required by a process and type of material used in a given layer. Candidate masks are reconciled with the process constraints through a constrained optimization.

  4. EUVL defect printability: an industry challenge

    NASA Astrophysics Data System (ADS)

    Kwon, Hyuk Joo; Teki, Ranganath; Harris-Jones, Jenah; Cordes, Aaron

    2012-02-01

    Extreme ultraviolet (EUV) patterning appears feasible using currently available EUV exposure tools, but some issues must still be resolved for EUV patterning to be used in production. Defects in EUV mask blanks are one such major issue, as evidenced by the research focused on defect printability. Inspection tools are needed to detect phase defects on EUV mask blanks that could possibly print on the wafer. Currently available inspection tools can capture defects on the mask, but they also need to be able to classify possible printable defects. Defect classification for repair and mitigation of printable defects is very difficult using DUV inspection tools; however, if the actinic inspection tool (AIT) could gather defect information from more multilayer stacks, it may be able to separate printable defects from unprintable defects. If unprintable defects could be eliminated, the defect information could be used for mask pattern shifts to reduce printable defects. Fewer defects would need to be repaired if there were a better chance of capturing printable defects using an actinic inspection tool. Being able to detect printable defects on EUV blanks is therefore critical in mask making. In this paper, we describe the characterization of native phase defects in the manufacturing of EUV mask blanks using the state-of-the-art mask metrology equipment in SEMATECH's Mask Blank Development Center (MBDC). Commercially available quartz substrates were used and Mo/Si multilayers were deposited on the substrates to characterize phase defects. Programmed defects of various dimensions were also prepared using e-beam patterning technology on which multilayers were deposited. Transmission electron microscopy (TEM) was used to study multilayer profile changes, while SEMATECH's AIT was used to image defects and predict their printability. A defect library for native defects and printability of programmed phase defects is introduced. Finally technical challenges for EUV defect

  5. Automated and integrated mask generation from a CAD constructed 3D model.

    SciTech Connect

    Schiek, Richard Louis; Schmidt, Rodney Cannon

    2005-03-01

    We have developed and implemented a method which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micromachining. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology to the model. The 3D model is first separated into bodies that are non-intersecting, made from different materials or only linked through a ground plane. Next, for each body unique horizontal cross sections are located and arranged into a tree based on their topological relationship. A branch-wise search of the tree uncovers locations where deposition boundaries must lie and identifies candidate masks creating a generic mask set for the 3D model. Finally, in the last step specific process requirements are considered that may constrain the generic mask set.

  6. Experiments on the Fehrer-Raab effect and the 'Weather Station Model' of visual backward masking.

    PubMed

    Neumann, Odmar; Scharlau, Ingrid

    2007-11-01

    The Fehrer-Raab effect (simple reaction time is unaffected by metacontrast masking of the test stimulus) seems to imply that a stimulus can trigger a voluntary reaction without reaching a conscious representation. However, it is also possible that the mask triggers the reaction, and that the masked test stimulus causes a focussing of attention from which processing of the mask profits, thus reaching conscious representation earlier. This is predicted by the Weather Station Model of visual masking. Three experiments tested this explanation. Experiment 1 showed that the masked test stimulus caused a temporal shift of the mask. Experiment 2 showed that the reaction in the Fehrer-Raab effect was not exclusively triggered by a conscious representation of the test stimulus: the mask was involved in evoking the reaction. Experiment 3 again revealed a temporal shift of the mask. However, the shift was only about half as large as the Fehrer-Raab effect. The psychometric functions suggested that the observers used two different cues for their temporal order judgments. The results cast doubts on whether judged temporal order yields a direct estimate of the time of conscious perception. Some methodological alternatives are discussed. PMID:16715303

  7. Understanding EUV mask blank surface roughness induced LWR and associated roughness requirement

    SciTech Connect

    Yan, Pei-Yang; Zhang, Guojing; Gullickson, Eric M.; Goldberg, Kenneth A.; Benk, Markus P.

    2015-03-01

    Extreme ultraviolet lithography (EUVL) mask multi-layer (ML) blank surface roughness specification historically comes from blank defect inspection tool requirement. Later, new concerns on ML surface roughness induced wafer pattern line width roughness (LWR) arise. In this paper, we have studied wafer level pattern LWR as a function of EUVL mask surface roughness via High-NA Actinic Reticle Review Tool. We found that the blank surface roughness induced LWR at current blank roughness level is in the order of 0.5nm 3σ for NA=0.42 at the best focus. At defocus of ±40nm, the corresponding LWR will be 0.2nm higher. Further reducing EUVL mask blank surface roughness will increase the blank cost with limited benefit in improving the pattern LWR, provided that the intrinsic resist LWR is in the order of 1nm and above.

  8. Coatings on reflective mask substrates

    DOEpatents

    Tong, William Man-Wai; Taylor, John S.; Hector, Scott D.; Mangat, Pawitter J. S.; Stivers, Alan R.; Kofron, Patrick G.; Thompson, Matthew A.

    2002-01-01

    A process for creating a mask substrate involving depositing: 1) a coating on one or both sides of a low thermal expansion material EUVL mask substrate to improve defect inspection, surface finishing, and defect levels; and 2) a high dielectric coating, on the backside to facilitate electrostatic chucking and to correct for any bowing caused by the stress imbalance imparted by either other deposited coatings or the multilayer coating of the mask substrate. An film, such as TaSi, may be deposited on the front side and/or back of the low thermal expansion material before the material coating to balance the stress. The low thermal expansion material with a silicon overlayer and a silicon and/or other conductive underlayer enables improved defect inspection and stress balancing.

  9. A novel model building flow for the simulation of proximity effects of mask processes

    NASA Astrophysics Data System (ADS)

    Mas, Jonathan; Mittermeier, Engelbert

    2007-02-01

    Linearity- and proximity effects are present on actual masks even if manufactured with current state-of-the-art mask processes. Currently the mask writers rectify the difference on the target critical dimension generated by these effects by changing the dose in function of the density of the pattern. However, the accuracy of this compensation is limited resulting in a deviation dependent of the critical dimensions (CD) from the design. The consequences of these mask imperfections on the photolithographic results on the wafer get increasingly into focus with each shrink in the semiconductor technology. In this paper we will present a procedure for building mask proximity simulation models. In a first part this new flow will be introduced, then one application on the Electron beam lithography modelling is exposed.

  10. A study of defects on EUV mask using blank inspection, patterned mask inspection, and wafer inspection

    SciTech Connect

    Huh, S.; Ren, L.; Chan, D.; Wurm, S.; Goldberg, K. A.; Mochi, I.; Nakajima, T.; Kishimoto, M.; Ahn, B.; Kang, I.; Park, J.-O.; Cho, K.; Han, S.-I.; Laursen, T.

    2010-03-12

    The availability of defect-free masks remains one of the key challenges for inserting extreme ultraviolet lithography (EUVL) into high volume manufacturing. yet link data is available for understanding native defects on real masks. In this paper, a full-field EUV mask is fabricated to investigate the printability of various defects on the mask. The printability of defects and identification of their source from mask fabrication to handling were studied using wafer inspection. The printable blank defect density excluding particles and patterns is 0.63 cm{sup 2}. Mask inspection is shown to have better sensitivity than wafer inspection. The sensitivity of wafer inspection must be improved using through-focus analysis and a different wafer stack.

  11. Masked Translation Priming with Semantic Categorization: Testing the Sense Model

    ERIC Educational Resources Information Center

    Wang, Xin; Forster, Kenneth I.

    2010-01-01

    Four experiments are reported which were designed to test hypotheses concerning the asymmetry of masked translation priming. Experiment 1 confirmed the presence of L2-L1 priming with a semantic categorization task and demonstrated that this effect was restricted to exemplars. Experiment 2 showed that the translation priming effect was not due to…

  12. Mask process simulation for mask quality improvement

    NASA Astrophysics Data System (ADS)

    Takahashi, Nobuyasu; Goto, So; Tsunoda, Dai; Shin, So-Eun; Lee, Sukho; Shon, Jungwook; Park, Jisoong

    2015-10-01

    Demand for mask process correction (MPC) is growing facing the 14nm era. We have developed model based MPC and can generate mask contours by using this mask process model. This mask process model consists of EB (development) and etch, which employs a threshold (level set) model and a variable bias model respectively. The model calibration tool accepts both CD measurement results and SEM images. The simulation can generate mask image (contour), runs with distributed computing resources, and has scalable performance. The contour simulation shows the accuracy of the MPC correction visually and provides comprehensive information about hot spots in mask fabrication. Additionally, it is possible to improve lithography simulation quality by providing a simulated mask contour. In this paper, accuracy and computational performance of mask process simulation are shown. The focus is on the difference between the calibration methods using CDs or images.

  13. Actinic review of EUV masks: Status and recent results of the AIMS EUV system

    NASA Astrophysics Data System (ADS)

    Weiss, Markus R.; Hellweg, Dirk; Koch, Markus; Peters, Jan Hendrik; Perlitz, Sascha; Garetto, Anthony; Magnusson, Krister; Capelli, Renzo; Jindal, Vibhu

    2015-03-01

    The EUV mask infrastructure is of key importance for the successful introduction of EUV lithography into volume production. In particular, for the production of defect free masks an actinic review of potential defect sites is required. To realize such an actinic review tool, Carl Zeiss and the SEMATECH EUVL Mask Infrastructure consortium started a development program for an EUV aerial image metrology system, the AIMS™ EUV. In this paper, we discuss the current status of the prototype integration and show recent results.

  14. Evaluation of non-actinic EUV mask inspection and defect printability on multiple EUV mask absorbers

    NASA Astrophysics Data System (ADS)

    Badger, Karen; Gallagher, Emily; Seki, Kazunori; McIntyre, Gregory; Konishi, Toshio; Kodera, Yutaka; Redding, Vincent

    2013-06-01

    EUV wavelength inspection tools are several years away from product release. Until then, the EUV Lithography (EUVL) community faces the challenge of inspecting EUV masks at non-actinic wavelengths. It is critical to understand how to improve mask inspectability and defect sensitivity. The absorber stack is one contributor, since changing the film stack modifies image contrast. To study the effect, masks were fabricated from three different film stacks on which the thickness of the low reflective and absorber layers vary. These three absorbers are identified in this paper as Type A, Type B and Type C. All blanks had the same Ru-capped multi-layer substrate beneath the absorber stack. Inspection contrast, defect sensitivity and inspectability were measured on a 193nm wavelength inspection tool. The focus of this paper will be on inspection at the 193nm wavelength; however, simulated wafer results at the 13.5 nm EUV exposure wavelength will be included to anchor the relevance of the mask inspection results. A comparison of the different absorber stacks, the ability to detect defects on the various masks, and how defects on these substrates prints on wafer will be provided. This work addresses the gap between EUVL mask inspection and wafer defect printability and how the two views differ relative to various absorber stacks.

  15. An improved virtual aberration model to simulate mask 3D and resist effects

    NASA Astrophysics Data System (ADS)

    Kanaya, Reiji; Fujii, Koichi; Imai, Motokatsu; Matsuyama, Tomoyuki; Tsuzuki, Takao; Lin, Qun Ying

    2015-03-01

    As shrinkage of design features progresses, the difference in best focus positions among different patterns is becoming a fatal issue, especially when many patterns co-exist in a layer. The problem arises from three major factors: aberrations of projection optics, mask 3D topography effects, and resist thickness effects. Aberrations in projection optics have already been thoroughly investigated, but mask 3D topography effects and resist thickness effects are still under study. It is well known that mask 3D topography effects can be simulated by various Electro-magnetic Field (EMF) analysis methods. However, it is almost impossible to use them for full chip modeling because all of these methods are extremely computationally intensive. Consequently, they usually apply only to a limited range of mask patterns which are about tens of square micro meters in area. Resist thickness effects on best focus positions are rarely treated as a topic of lithography investigations. Resist 3D effects are treated mostly for resist profile prediction, which also requires an intensive EMF analysis when one needs to predict it accurately. In this paper, we present a simplified Virtual Aberration (VA) model to simulate both mask 3D induced effects and resist thickness effects. A conventional simulator, when applied with this simplified method, can factor in both mask 3D topography effects and resist thickness effects. Thus it can be used to model inter-pattern Best Focus Difference (BFD) issues with the least amount of rigorous EMF analysis.

  16. Neonatal resuscitation 3: manometer use in a model of face mask ventilation

    PubMed Central

    O'Donnell, C; Davis, P; Lau, R; Dargaville, P; Doyle, L; Morley, C

    2005-01-01

    Background: Adequate ventilation is the key to successful neonatal resuscitation. Positive pressure ventilation (PPV) is initiated with manual ventilation devices via face masks. These devices may be used with a manometer to measure airway pressures delivered. The expiratory tidal volume measured at the mask (VTE(mask)) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. Aim: To assess the effect of viewing a manometer on the peak inspiratory pressures used, the volume delivered, and leakage from the face mask during PPV with two manual ventilation devices in a model of neonatal resuscitation. Methods: Participants gave PPV to a modified resuscitation mannequin using a Laerdal infant resuscitator and a Neopuff infant resuscitator at specified pressures ensuring adequate chest wall excursion. Each participant gave PPV to the mannequin with each device twice, viewing the manometer on one occasion and unable to see the manometer on the other. Data from participants were averaged for each device used with the manometer and without the manometer separately. Results: A total of 7767 inflations delivered by the 18 participants were recorded and analysed. Peak inspiratory pressures delivered were lower with the Laerdal device. There were no differences in leakage from the face mask or volumes delivered. Whether or not the manometer was visible made no difference to any measured variable. Conclusions: Viewing a manometer during PPV in this model of neonatal resuscitation does not affect the airway pressure or tidal volumes delivered or the degree of leakage from the face mask. PMID:15871988

  17. Optimization of mask manufacturing rule check constraint for model based assist feature generation

    NASA Astrophysics Data System (ADS)

    Shim, Seongbo; Kim, Young-chang; Chun, Yong-jin; Lee, Seong-Woo; Lee, Suk-joo; Choi, Seong-woon; Han, Woo-sung; Chang, Seong-hoon; Yoon, Seok-chan; Kim, Hee-bom; Ki, Won-tai; Woo, Sang-gyun; Cho, Han-gu

    2008-11-01

    space restriction. The test mask for this experimental work includes not only typical split patterns but also real device patterns that are generated by in-house model-based assist feature generation tool. We analyzed the mask writing result for typical patterns and compared the simulation result, and wafer result for real device patterns.

  18. DIET Processes on Ruthenium Surfaces Related to Extreme Ultraviolet Lithography (EUVL)

    SciTech Connect

    Yakshinskiy, B.; Wasielewski, R; Loginova, E; Hedhili, M; Madey, T

    2008-01-01

    The aim of this work is to provide insights into desorption induced by electronic transitions (DIET) processes that affect the reflectivity of ruthenium-capped Mo/Si multilayer mirrors working under EUVL (extreme ultraviolet lithography) operating conditions (high vacuum, and 13.5 nm (92 eV) photons). Critical issues are associated with possible oxidation of the 2 nm thick Ru capping layer due to the inevitable background pressure of H{sub 2}O, and carbon build up due to background hydrocarbons. In the present work, we discuss aspects of the radiation-induced surface chemistry of Ru irradiated by 100 eV electrons and 92 eV photons. The cross section for electron-stimulated desorption of oxygen from O-covered Ru is 6 x 10{sup -19} cm{sup 2}. Carbon accumulation several nm thick occurs on the Ru surface during electron irradiation in methyl methacrylate (MMA) vapor, a model background impurity hydrocarbon. Radiation damage by low-energy secondary electrons is believed to dominate over direct photoexcitation of adsorbates under EUVL conditions. The secondary electron yield from Ru varies strongly with photon energy, and is 0.02 electrons/photon at 92 eV.

  19. DIET processes on ruthenium surfaces related to extreme ultraviolet lithography (EUVL)

    NASA Astrophysics Data System (ADS)

    Yakshinskiy, B. V.; Wasielewski, R.; Loginova, E.; Hedhili, M. N.; Madey , T. E.

    2008-10-01

    The aim of this work is to provide insights into desorption induced by electronic transitions (DIET) processes that affect the reflectivity of ruthenium-capped Mo/Si multilayer mirrors working under EUVL (extreme ultraviolet lithography) operating conditions [high vacuum, and 13.5 nm (92 eV) photons]. Critical issues are associated with possible oxidation of the 2 nm thick Ru capping layer due to the inevitable background pressure of H 2O, and carbon build up due to background hydrocarbons. In the present work, we discuss aspects of the radiation-induced surface chemistry of Ru irradiated by 100 eV electrons and 92 eV photons. The cross section for electron-stimulated desorption of oxygen from O-covered Ru is ˜6 × 10 -19 cm 2. Carbon accumulation several nm thick occurs on the Ru surface during electron irradiation in methyl methacrylate (MMA) vapor, a model background impurity hydrocarbon. Radiation damage by low-energy secondary electrons is believed to dominate over direct photoexcitation of adsorbates under EUVL conditions. The secondary electron yield from Ru varies strongly with photon energy, and is ˜0.02 electrons/photon at 92 eV.

  20. Evaluating printability of buried native extreme ultraviolet mask phase defects through a modeling and simulation approach

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Mihir; Jindal, Vibhu; Basavalingappa, Adarsh; Herbol, Henry; Harris-Jones, Jenah; Jang, Il-Yong; Goldberg, Kenneth A.; Mochi, Iacopo; Marokkey, Sajan; Demmerle, Wolfgang; Pistor, Thomas V.; Denbeaux, Gregory

    2015-04-01

    Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the printability of the native extreme ultraviolet (EUV) mask defects. In this work, we performed a systematic study of native mask defects to understand the defect printability they cause. The multilayer growth over native substrate mask blank defects was correlated to the multilayer growth over regular-shaped defects having similar profiles in terms of their width and height. To model the multilayer growth over the defects, a multilayer growth model based on a level-set technique was used that took into account the tool deposition conditions of the Veeco Nexus ion beam deposition tool. Further, the printability of the characterized native defects was studied at the SEMATECH-Berkeley Actinic Inspection Tool (AIT), an EUV mask-imaging microscope at Lawrence Berkeley National Laboratory. Printability of the modeled regular-shaped defects, which were propagated up the multilayer stack using level-set growth model, was studied using defect printability simulations implementing the waveguide algorithm. Good comparison was observed between AIT and the simulation results, thus demonstrating that multilayer growth over a defect is primarily a function of a defect's width and height, irrespective of its shape.

  1. Extreme ultraviolet patterned mask inspection performance of advanced projection electron microscope system for 11nm half-pitch generation

    NASA Astrophysics Data System (ADS)

    Hirano, Ryoichi; Iida, Susumu; Amano, Tsuyoshi; Watanabe, Hidehiro; Hatakeyama, Masahiro; Murakami, Takeshi; Suematsu, Kenichi; Terao, Kenji

    2016-03-01

    Novel projection electron microscope optics have been developed and integrated into a new inspection system named EBEYE-V30 ("Model EBEYE" is an EBARA's model code) , and the resulting system shows promise for application to half-pitch (hp) 16-nm node extreme ultraviolet lithography (EUVL) patterned mask inspection. To improve the system's inspection throughput for 11-nm hp generation defect detection, a new electron-sensitive area image sensor with a high-speed data processing unit, a bright and stable electron source, and an image capture area deflector that operates simultaneously with the mask scanning motion have been developed. A learning system has been used for the mask inspection tool to meet the requirements of hp 11-nm node EUV patterned mask inspection. Defects are identified by the projection electron microscope system using the "defectivity" from the characteristics of the acquired image. The learning system has been developed to reduce the labor and costs associated with adjustment of the detection capability to cope with newly-defined mask defects. We describe the integration of the developed elements into the inspection tool and the verification of the designed specification. We have also verified the effectiveness of the learning system, which shows enhanced detection capability for the hp 11-nm node.

  2. Considering mask pellicle effect for more accurate OPC model at 45nm technology node

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Heng; Liu, Qingwei; Zhang, Liguo

    2008-11-01

    Now it comes to the 45nm technology node, which should be the first generation of the immersion micro-lithography. And the brand-new lithography tool makes many optical effects, which can be ignored at 90nm and 65nm nodes, now have significant impact on the pattern transmission process from design to silicon. Among all the effects, one that needs to be pay attention to is the mask pellicle effect's impact on the critical dimension variation. With the implement of hyper-NA lithography tools, light transmits the mask pellicle vertically is not a good approximation now, and the image blurring induced by the mask pellicle should be taken into account in the computational microlithography. In this works, we investigate how the mask pellicle impacts the accuracy of the OPC model. And we will show that considering the extremely tight critical dimension control spec for 45nm generation node, to take the mask pellicle effect into the OPC model now becomes necessary.

  3. Model-based mask data preparation (MB-MDP) and its impact on resist heating

    NASA Astrophysics Data System (ADS)

    Fujimura, Aki; Kamikubo, Takashi; Bork, Ingo

    2011-04-01

    Complex mask shapes will be required on critical layer masks for 20nm logic node, threatening to explode the mask write times. Model-Based Mask Data Preparation (MB-MDP) has been introduced to reduce the shot count required to write complex masks while simultaneously improving resolution and dose margin of sub-100nm features. For production use of MB-MDP, a number of questions have been raised and answered. This paper summarizes these potential issues and their resolutions. In particular, the paper takes an in-depth look at one of the questions: impact of overlapping shots on heating effect. The paper concludes that while heating effect is an important issue for all e-beam writing even with conventional non-overlapping shots, overall dose density per unit time over microns of space is the principal driver behind heating effects. Highly local shot density and shot sequencing does not affect heating significantly, particularly for smaller shots. MB-MDP does not introduce any additional concerns.

  4. Mathematical modeling of pattern formation caused by drying of colloidal film under a mask.

    PubMed

    Tarasevich, Yuri Yu; Vodolazskaya, Irina V; Sakharova, Lyudmila V

    2016-02-01

    In our model, we simulate an experiment (D.J. Harris, H. Hu, J.C. Conrad, J.A. Lewis, Patterning colloidal films via evaporative lithography, Phys. Rev. Lett. 98, 148301 (2007)). A thin colloidal sessile droplet is allowed to dry out on a horizontal hydrophilic surface. A mask just above the droplet predominantly allows evaporation from the droplet free surface directly beneath the holes in the mask. We consider one special case, when the holes in the mask are arranged so that the system has rotational symmetry of order m . We use a speculative evaporative flux to mimic the real system. Advection, diffusion, and sedimentation are taken into account. FlexPDE is utilized to solve an advection-diffusion equation using the finite element method. The simulation demonstrates that the colloidal particles accumulate below the holes as the solvent evaporates. Diffusion can reduce this accumulation. PMID:26920529

  5. Neonatal resuscitation 1: a model to measure inspired and expired tidal volumes and assess leakage at the face mask

    PubMed Central

    O'Donnell, C; Kamlin, C; Davis, P; Morley, C

    2005-01-01

    Background: Neonatal resuscitation is a common and important intervention, and adequate ventilation is the key to success. In the delivery room, positive pressure ventilation is given with manual ventilation devices using face masks. Mannequins are widely used to teach and practise this technique. During both simulated and real neonatal resuscitation, chest excursion is used to assess tidal volume delivery, and leakage from the mask is not measured. Objective: To describe a system that allows measurement of mask leakage and estimation of tidal volume delivery. Methods: Respiratory function monitors, a modified resuscitation mannequin, and a computer were used to measure leakage from the mask and to assess tidal volume delivery in a model of neonatal resuscitation. Results: The volume of gas passing through a flow sensor was measured at the face mask. This was a good estimate of the tidal volume entering and leaving the lung in this model. Gas leakage between the mask and mannequin was also measured. This occurred principally during inflation, although gas leakage during deflation was seen when the total leakage was large. A volume of gas that distended the mask but did not enter the lung was also measured. Conclusion: This system can be used to assess the effectiveness of positive pressure ventilation given using a face mask during simulated neonatal resuscitation. It could be useful for teaching neonatal resuscitation and assessing ventilation through a face mask. PMID:15871990

  6. Low CoO grazing incidence collectors for EUVL HVM

    NASA Astrophysics Data System (ADS)

    Bianucci, G.; Cassol, G. L.; Ceglio, N. M.; Valsecchi, G.; Zocchi, F.

    2012-03-01

    Media Lario Technologies (MLT) uses its proprietary replication by electroforming technology to manufacture grazing incidence collectors in support of the EUVL technology roadmap. With the experience of more than 20 alpha and preproduction collectors installed to date, and with the development results of the Advanced Cooling Architecture (ACA) for High Volume Manufacturing (HVM) collector generation, we present optical, lifetime, and thermo-optical performance of the grazing incidence collectors, meeting the requirements of HVM scanners for a throughput target of more than 100 wafers per hour. The ruthenium reflective layer of the grazing incidence collector is very forgiving to the hostile environment of the plasma sources, as proven by the installed base with 1-year lifetime expectancy. On the contrary, the multilayer-based collector is vulnerable to Sn deposition and ion bombardment, and the need to mitigate this issue has led to a steady increase of the complexity of the LPP source architecture. With the awareness that the source and collector module is the major risk against the timely adoption of EUVL in HVM, we propose a new paradigm that, by using the field-proven design simplicity and robustness of the grazing incidence collector in both LDP and LPP sources, effectively reduces the risk of both source architectures and improves their reliability.

  7. Design and fabrication considerations of EUVL collectors for HVM

    NASA Astrophysics Data System (ADS)

    Bianucci, G.; Cassol, G. L.; Kools, J.; Prea, M.; Salmaso, G.; Valsecchi, G.; Zocchi, F. E.; Bolshukhin, D.; Schürmann, M.; Schriever, G.; Mader, A.; Zink, P.

    2009-03-01

    The power roadmap for EUVL high volume manufacturing (HVM) exceeds the 200W EUV in-band power at intermediate focus, thus posing more demanding requirements on HVM sources, debris suppression systems and collectors. Starting from the lessons learned in the design and fabrication of the grazing incidence collectors for the Alpha EUVL scanners, Media Lario Technologies is developing HVM optical solutions that enable designed-in lifetime improvements, such as larger source-collector distances, optimized collection efficiency through larger collected solid angles, and customized EUV reflective layers. The optical design of an HVM collector is described together with the selection of the sacrificial ruthenium reflective layer. The water cooling layout of the collector is evolved from the integrated cooling technology developed at Alpha level into an innovative cooling layout that minimizes the thermal gradients across the mirrors and allows controlling the optical performance at the far-field plane. Finally, the evolution of the collector's manufacturing technologies for HVM is discussed. XTREME technologies and Philips Extreme UV support this work by integrating the collector in the complete source collector module (SoCoMo). At system level, each component of the SoCoMo is part of a development and improvement plan leading to a comprehensive system that will fulfill the 200+ W EUV in-band power at intermediate focus.

  8. Determining the critical size of EUV mask substrate defects

    SciTech Connect

    Goldberg, Kenneth A.; Gullikson, Eric M.; Han, Hakseung; Cho, Wonil; Jeon, Chan-Uk; Wurm, Stefan

    2008-05-26

    Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tools. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed.

  9. Determining the Critcial Size of EUV Mask Substrate Defects

    SciTech Connect

    Mccall, Monnikue M; Han, Hakseung; Cho, Wonil; Goldberg, Kenneth; Gullikson, Eric; Jeon, Chan-Uk; Wurm, Stefan

    2008-02-28

    Determining the printability of substrate defects beneath the extreme ultraviolet (EUV) reflecting multilayer stack is an important issue in EUVL lithography. Several simulation studies have been performed in the past to determine the tolerable defect size on EUV mask blank substrates but the industry still has no exact specification based on real printability tests. Therefore, it is imperative to experimentally determine the printability of small defects on a mask blanks that are caused by substrate defects using direct printing of programmed substrate defect in an EUV exposure tool. SEMATECH fabricated bump type program defect masks using standard electron beam lithography and performed printing tests with the masks using an EUV exposure tool. Defect images were also captured using SEMATECH's Berkeley Actinic Imaging Tool in order to compare aerial defect images with secondary electron microscope images from exposed wafers. In this paper, a comprehensive understanding of substrate defect printability will be presented and printability specifications of EUV mask substrate defects will be discussed.

  10. Reflective masks for extreme ultraviolet lithography

    SciTech Connect

    Nguyen, Khanh Bao

    1994-05-01

    Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for 0.15 {mu}m wide defect lines. A long-term study of Mo/Si coating reflectivity revealed that Mo/Si coatings with Mo as the top layer suffer significant reductions in reflectivity over time due to oxidation.

  11. Investigating printability of native defects on EUV mask blanks through simulations and experiments

    NASA Astrophysics Data System (ADS)

    Upadhyaya, Mihir; Jindal, Vibhu; Herbol, Henry; Jang, Il-Yong; Kwon, Hyuk Joo; Harris-Jones, Jenah; Denbeaux, Gregory

    2014-04-01

    Availability of defect-free masks is considered to be a critical issue for enabling extreme ultraviolet lithography (EUVL) as the next generation technology. Since completely defect-free masks will be hard to achieve, it is essential to have a good understanding of the defect printability as well as the fundamental aspects of a defect that result in the defects being printed. In this work, the native mask blank defects were characterized using atomic force microscopy (AFM) and cross-section transmission electron microscopy (TEM), and the defect printability of the characterized native mask defects was evaluated using finite-difference time-domain (FDTD) simulations. The simulation results were compared with the through-focus aerial images obtained at the SEMATECH Actinic Inspection Tool (AIT) at Lawrence Berkeley National Lab (LBNL) for the characterized defects. There was a reasonable agreement between the through-focus FDTD simulation results and the AIT results. To model the Mo/Si multilayer growth over the native defects, which served as the input for the FDTD simulations, a level-set technique was used to predict the evolution of the multilayer disruption over the defect. Unlike other models that assume a constant flux of atoms (of materials to be deposited) coming from a single direction, this model took into account the direction and incident fluxes of the materials to be deposited, as well as the rotation of the mask substrate, to accurately simulate the actual deposition conditions. The modeled multilayer growth was compared with the cross-section TEM images, and a good agreement was observed between them.

  12. Simulated masking of right whale sounds by shipping noise: incorporating a model of the auditory periphery.

    PubMed

    Cunningham, Kane A; Mountain, David C

    2014-03-01

    Many species of large, mysticete whales are known to produce low-frequency communication sounds. These low-frequency sounds are susceptible to communication masking by shipping noise, which also tends to be low frequency in nature. The size of these species makes behavioral assessment of auditory capabilities in controlled, captive environments nearly impossible, and field-based playback experiments are expensive and necessarily limited in scope. Hence, it is desirable to produce a masking model for these species that can aid in determining the potential effects of shipping and other anthropogenic noises on these protected animals. The aim of this study was to build a model that combines a sophisticated representation of the auditory periphery with a spectrogram-based decision stage to predict masking levels. The output of this model can then be combined with a habitat-appropriate propagation model to calculate the potential effects of noise on communication range. For this study, the model was tested on three common North Atlantic right whale communication sounds, both to demonstrate the method and to probe how shipping noise affects the detection of sounds with varying spectral and temporal characteristics. PMID:24606298

  13. Liftoff lithography of metals for extreme ultraviolet lithography mask absorber layer patterning

    NASA Astrophysics Data System (ADS)

    Lyons, Adam; Teki, Ranganath; Hartley, John

    2012-03-01

    The authors present a process for patterning Extreme Ultraviolet Lithography (EUVL) mask absorber metal using electron beam evaporation and bi-layer liftoff lithography. The Line Edge Roughness (LER) and Critical Dimension Uniformity (CDU) of patterned chrome absorber are determined for various chrome thicknesses on silicon substrates, and the viability of the method for use with nickel absorber and on EUVL masks is demonstrated. Scanning Electron Microscope (SEM) data is used with SuMMIT software to determine the absorber LER and CDU. The Lawrence Berkeley National Labs Actinic Inspection Tool (AIT) is used to verify the printability of the pattern down to 24nm half pitch. The effect of processing on the integrity of the mask multilayer is measured using an actinic reflectometer at the College of Nanoscale Science and Engineering.

  14. Method for fabricating an ultra-low expansion mask blank having a crystalline silicon layer

    DOEpatents

    Cardinale, Gregory F.

    2002-01-01

    A method for fabricating masks for extreme ultraviolet lithography (EUVL) using Ultra-Low Expansion (ULE) substrates and crystalline silicon. ULE substrates are required for the necessary thermal management in EUVL mask blanks, and defect detection and classification have been obtained using crystalline silicon substrate materials. Thus, this method provides the advantages for both the ULE substrate and the crystalline silicon in an Extreme Ultra-Violet (EUV) mask blank. The method is carried out by bonding a crystalline silicon wafer or member to a ULE wafer or substrate and thinning the silicon to produce a 5-10 .mu.m thick crystalline silicon layer on the surface of the ULE substrate. The thinning of the crystalline silicon may be carried out, for example, by chemical mechanical polishing and if necessary or desired, oxidizing the silicon followed by etching to the desired thickness of the silicon.

  15. Electron Beam Lithography Simulation for the Patterning of Extreme Ultraviolet Masks

    NASA Astrophysics Data System (ADS)

    Tsikrikas, N.; Patsis, G. P.; Raptis, I.; Gerardino, A.; Quesnel, E.

    2008-06-01

    Extreme ultraviolet lithography (EUVL) mask is a complex multilayer stack, fabricated with electron-beam lithography. Detailed understanding of the scattering events and energy loss mechanism of the electron beam within this stack is mandatory due to the high accuracy requirements of the fabrication process. Simulation of electron-beam lithography is performed incorporating the details of the mask material-stack and the metrological information of the final layout is quantified. The effect of the Mo-Si multilayer of the EUVL mask blank on the deposited energy in the resist film is investigated. Simulation of complex layout containing features of various sizes down to 100 nm reproduced experimental metrology trends on the fine features of the layout.

  16. Mask modeling in the low k1 and ultrahigh NA regime: phase and polarization effects (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Erdmann, Andreas

    2005-06-01

    This paper reviews state of the art mask modeling for optical lithography. Rigorous electromagnetic field (EMF) simu-lation of light diffraction from optical masks is compared to the traditional assumption of an infinitely thin mask, the so called Kirchhoff approach. Rigorous EMF simulation will be employed to analyze mask polarization phenomena which become important in the ultrahigh NA regime. Several important lithographic phenomena, which can be explained only with rigorous EMF simulation, are discussed. This includes the printability of small assist features, intensity imbalanc-ing for alternating PSM, and process window deformations. The paper concludes with a discussion on material issues and algorithmic extensions which will be necessary for an accurate modeling of future mask technology.

  17. Enhanced defect detection capability using learning system for extreme ultraviolet lithography mask inspection tool with projection electron microscope optics

    NASA Astrophysics Data System (ADS)

    Hirano, Ryoichi; Hatakeyama, Masahiro; Terao, Kenji; Watanabe, Hidehiro

    2016-04-01

    Extreme ultraviolet lithography (EUVL) patterned mask defect detection is a major issue that must be addressed to realize EUVL-based device fabrication. We have designed projection electron microscope (PEM) optics for integration into a mask inspection system, and the resulting PEM system performs well in half-pitch (hp) 16-nm-node EUVL patterned mask inspection applications. A learning system has been used in this PEM patterned mask inspection tool. The PEM identifies defects using the "defectivity" parameter that is derived from the acquired image characteristics. The learning system has been developed to reduce the labor and the costs associated with adjustment of the PEM's detection capabilities to cope with newly defined mask defects. The concepts behind this learning system and the parameter optimization flow are presented here. The learning system for the PEM is based on a library of registered defects. The learning system then optimizes the detection capability by reconciling previously registered defects with newly registered defects. Functional verification of the learning system is also described, and the system's detection capability is demonstrated by applying it to the inspection of hp 11-nm EUV masks. We can thus provide a user-friendly mask inspection system with reduced cost of ownership.

  18. Growth and Printability of Multilayer Phase Defects on EUV MaskBlanks

    SciTech Connect

    Liang, Ted; Ultanir, Erdem; Zhnag, Guojing; Park, Seh-Jin; Anderson, Erik; Gullikson, Eric; Naulleau, Patrick; Salmassi, Farhad; Mirkarimi, Paul; Spiller, Eberhard; Baker, Sherry

    2007-06-10

    The ability to fabricate defect-free mask blanks is a well-recognized challenge in enabling extreme ultraviolet lithography (EUVL) for semiconductor manufacturing. Both the specification and reduction of defects necessitate the understanding of their printability and how they are generated and grow during Mo-Si multilayer (ML) deposition. A ML phase defect can be depicted by its topographical profile on the surface as either a bump or pit, which is then characterized by height or depth and width. The complexity of such seemingly simple phase defects lies in the many ways they can be generated and the difficulties of measuring their physical shape/size and optical effects on printability. An effective way to study phase defects is to use a programmed defect mask (PDM) as 'model' test sample where the defects are produced with controlled growth on a ML blank and accurate placement in varying proximity to absorber patterns on the mask. This paper describes our recent study of ML phase defect printability with resist data from exposures of a ML PDM on the EUV micro-exposure tool (MET, 5X reduction with 0.3NA).

  19. Impact of mask line edge roughness and statistical noise on next generation mask making

    NASA Astrophysics Data System (ADS)

    Kim, Byung Gook; Choi, Jin; Lee, Sang Hee; Jeon, Chan Uk

    2012-06-01

    As extreme ultraviolet lithography (EUVL) moves toward high volume manufacturing and pushes to increasingly smaller critical dimensions, achieving the stringent requirements for line edge roughness (LER) is increasingly challenging. For the 22 nm half-pitch node and beyond, the International Roadmap for Semiconductors requires less than 1.6 nm of line width roughness (LWR) on the wafer. The major contributor of this tight LWR is wafer resist LER and mask LER. However, in current ITRS, there is no guideline for mask LER. While significant progress has been made to reduce the resist of the LER on the wafer, it is not yet clear how much the mask LER should be improved for a 22 nm half-pitch node application. Additionally, there are various approaches to obtaining a smaller LER on the mask. It could be improved either by reducing well-known statistical noise or manipulating some process condition or material. Both approaches are effective in improving the LER, however, they shows a different result in mask CD uniformity itself. In this paper, in addition to setting the criteria of the mask LER, we will discuss how tight the mask LER is required to be and what kind of approach is desirable with regards to the LER and CD uniformity. Finally, an analysis of the LER and CD variation provides some insights into the impact of the next generation mask infrastructure.

  20. Image-based EUVL aberration metrology

    NASA Astrophysics Data System (ADS)

    Fenger, Germain Louis

    A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberration. As resolution of nanolithography systems increases, effects of wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate in-situ aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials.

  1. Source-mask selection using computational lithography: further investigation incorporating rigorous resist models

    NASA Astrophysics Data System (ADS)

    Kapasi, Sanjay; Robertson, Stewart; Biafore, John; Smith, Mark D.

    2009-12-01

    Recent publications have emphasized the criticality of computational lithography in source-mask selection for 32 and 22 nm technology nodes. Lithographers often select the illuminator geometries based on analyzing aerial images for a limited set of structures using computational lithography tools. Last year, Biafore, et al1 demonstrated the divergence between aerial image models and resist models in computational lithography. In a follow-up study2, it was illustrated that optimal illuminator is different when selected based on resist model in contrast to aerial image model. In the study, optimal source shapes were evaluated for 1D logic patterns using aerial image model and two distinct commercial resist models. Physics based lumped parameter resist model (LPM) was used. Accurately calibrated full physical models are portable across imaging conditions compared to the lumped models. This study will be an extension of previous work. Full physical resist models (FPM) with calibrated resist parameters3,4,5,6 will be used in selecting optimum illumination geometries for 1D logic patterns. Several imaging parameters - like Numerical Aperture (NA), source geometries (Annular, Quadrupole, etc.), illumination configurations for different sizes and pitches will be explored in the study. Our goal is to compare and analyze the optimal source-shapes across various imaging conditions. In the end, the optimal source-mask solution for given set of designs based on all the models will be recommended.

  2. Infinitely high selective inductively coupled plasma etching of an indium tin oxide binary mask structure for extreme ultraviolet lithography

    SciTech Connect

    Park, Y. R.; Ahn, J. H.; Kim, J. S.; Kwon, B. S.; Lee, N.-E.; Kang, H. Y.; Hwangbo, C. K.; Ahn, Jinho; Seo, Hwan Seok

    2010-07-15

    Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics with a completely different configuration than those of conventional photolithography. This study investigated the etching properties of indium tin oxide (ITO) binary mask materials for EUVL, such as ITO (absorber layer), Ru (capping/etch-stop layer), and a Mo-Si multilayer (reflective layer), by varying the Cl{sub 2}/Ar gas flow ratio, dc self-bias voltage (V{sub dc}), and etch time in inductively coupled plasmas. The ITO absorber layer needs to be etched with no loss in the Ru layer on the Mo-Si multilayer for fabrication of the EUVL ITO binary mask structure proposed here. The ITO layer could be etched with an infinitely high etch selectivity over the Ru etch-stop layer in Cl{sub 2}/Ar plasma even with a very high overetch time.

  3. Phase defect mitigation strategy: fiducial mark requirements on extreme ultraviolet lithography mask

    NASA Astrophysics Data System (ADS)

    Murachi, Tetsunori; Amano, Tsuyoshi; Oh, Sung Hyun

    2012-03-01

    For Extreme Ultra-Violet Lithography (EUVL), fabrication of defect free multi-layered (ML) mask blanks is one of the difficult challenges. ML defects come from substrate defects and adders during ML coating, cannot be removed, and are called as phase defect. If we can accept ML blanks with certain number of phase defects, the blank yield will be drastically up. In order to use such blanks, the phase defects need to be identified and located during ML blank defect inspection before absorber patterning. To locate phase defects on the blanks accurately and precisely, Fiducial Marks (FM) on ML blanks are needed for mask alignment and defect location information. The proposed requirement of defect location accuracy is <=20 nm [1]. In this paper, we will present the result of feasibility study on the requirements of FM on EUVL mask by simulations & experiments to establish the phase defect mitigation method with EUV Actinic Blank Inspection (ABI) tool. And the optimum ranges of FM line width, depth, and fabrication method on EUVL mask based on above results are >= 5 um line width, >= 100 nm depth FM etched into ML respectively, and additional finer FMs for magnified optics.

  4. Formal specification and verification of a fault-masking and transient-recovery model for digital flight-control systems

    NASA Technical Reports Server (NTRS)

    Rushby, John

    1991-01-01

    The formal specification and mechanically checked verification for a model of fault-masking and transient-recovery among the replicated computers of digital flight-control systems are presented. The verification establishes, subject to certain carefully stated assumptions, that faults among the component computers are masked so that commands sent to the actuators are the same as those that would be sent by a single computer that suffers no failures.

  5. Method for characterizing mask defects using image reconstruction from X-ray diffraction patterns

    DOEpatents

    Hau-Riege, Stefan Peter

    2007-05-01

    The invention applies techniques for image reconstruction from X-ray diffraction patterns on the three-dimensional imaging of defects in EUVL multilayer films. The reconstructed image gives information about the out-of-plane position and the diffraction strength of the defect. The positional information can be used to select the correct defect repair technique. This invention enables the fabrication of defect-free (since repaired) X-ray Mo--Si multilayer mirrors. Repairing Mo--Si multilayer-film defects on mask blanks is a key for the commercial success of EUVL. It is known that particles are added to the Mo--Si multilayer film during the fabrication process. There is a large effort to reduce this contamination, but results are not sufficient, and defects continue to be a major mask yield limiter. All suggested repair strategies need to know the out-of-plane position of the defects in the multilayer.

  6. AutoMOPS- B2B and B2C in mask making: Mask manufacturing performance and customer satisfaction improvement through better information flow management using generic models and standardized languages

    NASA Astrophysics Data System (ADS)

    Filies, Olaf; de Ridder, Luc; Rodriguez, Ben; Kujiken, Aart

    2002-03-01

    Semiconductor manufacturing has become a global business, in which companies of different size unite in virtual enterprises to meet new opportunities. Therefore Mask manufacturing is a key business, but mask ordering is a complex process and is always critical regarding design to market time, even though mask complexity and customer base are increasing using a wide variety of different mask order forms which are frequently faulty and very seldom complete. This is effectively blocking agile manufacturing and can tie wafer fabs to a single mask The goal of the project is elimination of the order verification through paperless, electronically linked information sharing/exchange between chip design, mask production and production stages, which will allow automation of the mask preparation. To cover these new techniques and their specifications as well as the common ones with automated tools a special generic Meta-model will be generated, based on the current standards for mask specifications, including the requirements from the involved partners (Alcatel Microelectronics, Altis, Compugraphics, Infineon, Nimble, Sigma-C), the project works out a pre-normative standard. The paper presents the current status of work. This work is partly funded by the Commission of the European Union under the Fifth Framework project IST-1999-10332 AutoMOPS.

  7. Extreme ultraviolet lithography patterned mask defect detection performance evaluation toward 16- to 11-nm half-pitch generation

    NASA Astrophysics Data System (ADS)

    Hirano, Ryoichi; Iida, Susumu; Amano, Tsuyoshi; Watanabe, Hidehiro; Hatakeyama, Masahiro; Murakami, Takeshi; Yoshikawa, Shoji; Terao, Kenji

    2015-07-01

    High-sensitivity and low-noise extreme ultraviolet (EUV) mask pattern defect detection is one of the major issues remaining to be addressed in device fabrication using extreme ultraviolet lithography (EUVL). We have designed a projection electron microscopy (PEM) system, which has proven to be quite promising for half-pitch (hp) 16-nm node to hp 11-nm node mask inspection. The PEM system was integrated into a pattern inspection system for defect detection sensitivity evaluation. To improve the performance of hp 16-nm patterned mask defect detection toward hp 11-nm EUVL patterned mask, defect detection signal characteristics, which depend on hp 64-nm pattern image intensity deviation on EUVL mask, were studied. Image adjustment effect of the captured images for die-to-die defect detection was evaluated before the start of the defect detection image-processing sequence. Image correction of intrafield intensity unevenness and L/S pattern image contrast deviation suppresses the generation of false defects. Captured images of extrusion and intrusion defects in hp 64-nm L/S patterns were used for detection. Applying the image correction for defect detection, 12-nm sized intrusion defect, which was smaller than our target size for hp 16-nm defect detection requirements, was identified without false defects.

  8. Actinic review of EUV masks: status and recent results of the AIMSTM EUV system

    NASA Astrophysics Data System (ADS)

    Perlitz, Sascha; Peters, Jan Hendrik; Weiss, Markus; Hellweg, Dirk; Capelli, Renzo; Magnusson, Krister; Malloy, Matt; Wurm, Stefan

    2015-10-01

    Key enabler of the successful introduction of EUV lithography into volume production is the EUV mask infrastructure. For the production of defect free masks, actinic review of potential defect sites to decide on the need for repair or compensation is required. Also, the repair or compensation with the ZEISS MERiT electron beam repair tool needs actinic verification in a closed loop mask repair solution. For the realization of actinic mask review, ZEISS and the SEMATECH EUVL Mask Infrastructure consortium started a development program for an EUV aerial image metrology system, the AIMSTM EUV, with realization of a prototype tool. The development and prototype realization of the AIMSTM EUV has entered the tool calibration and qualification phase utilizing the achieved capabilities of EUV aerial image acquisition and EUV mask handling. In this paper, we discuss the current status of the prototype qualification and show recent measurement results.

  9. Recent advances in SEMATECH's mask blank development program, the remaining technical challenges, and future outlook

    NASA Astrophysics Data System (ADS)

    Goodwin, Frank; Kearney, Patrick; Kadaksham, Arun J.; Wurm, Stefan

    2013-10-01

    The ability of optical lithography to steadily produce images at increasingly smaller dimension while maintaining pattern fidelity of devices with greater complexity has enabled the success of Moore's Law. Although 193 nm immersion and double patterning techniques have proven successful in extending optical lithography, the strategies proposed for further extension are too costly to support device manufacturing. As a result, greater focus has been shifted to resolving the challenges hindering extreme ultraviolet lithography (EUVL) adoption as the mainstream lithography solution. While similar to conventional optical lithography, there are unique challenges to EUVL, one of which is the change from transmission masks to the reflective masks required for EUVL. The use of reflective reticles greatly increases complexity of EUV reticle structure when compared to the binary masks used with optical lithography. Maximizing the reflectance an EUV mask requires the use of a multilayer Bragg reflector deposited on a finely polished substrate with a thin absorber film on top used to define the device pattern. Although similar in form to the substrates used in optical lithography, the tolerances on figure, surface finish, and defects are significantly more stringent for EUV substrates. Control of aberrations and maintaining pattern fidelity places tight constraints on the flatness and roughness of the EUV substrate; imperfections and particles can result in printable defects. The Bragg reflector of the EUV mask consists of 40 to 50 Si/Mo bi-layers deposited using an ion beam deposition tool. This film stack must be deposited to meet the reflectivity and uniformity requirements of the exposure tool and must be completely free of defects. The absorber film is typically a tantalum-based nitride layer selected for its ability to absorb EUV radiation and maintain thermal stability. The thickness and morphology of this film must be tightly controlled to enable use as the patterning

  10. Electron beam inspection of 16nm HP node EUV masks

    NASA Astrophysics Data System (ADS)

    Shimomura, Takeya; Narukawa, Shogo; Abe, Tsukasa; Takikawa, Tadahiko; Hayashi, Naoya; Wang, Fei; Ma, Long; Lin, Chia-Wen; Zhao, Yan; Kuan, Chiyan; Jau, Jack

    2012-11-01

    EUV lithography (EUVL) is the most promising solution for 16nm HP node semiconductor device manufacturing and beyond. The fabrication of defect free EUV mask is one of the most challenging roadblocks to insert EUVL into high volume manufacturing (HVM). To fabricate and assure the defect free EUV masks, electron beam inspection (EBI) tool will be likely the necessary tool since optical mask inspection systems using 193nm and 199nm light are reaching a practical resolution limit around 16nm HP node EUV mask. For production use of EBI, several challenges and potential issues are expected. Firstly, required defect detection sensitivity is quite high. According to ITRS roadmap updated in 2011, the smallest defect size needed to detect is about 18nm for 15nm NAND Flash HP node EUV mask. Secondly, small pixel size is likely required to obtain the high sensitivity. Thus, it might damage Ru capped Mo/Si multilayer due to accumulated high density electron beam bombardments. It also has potential of elevation of nuisance defects and reduction of throughput. These challenges must be solved before inserting EBI system into EUV mask HVM line. In this paper, we share our initial inspection results for 16nm HP node EUV mask (64nm HP absorber pattern on the EUV mask) using an EBI system eXplore® 5400 developed by Hermes Microvision, Inc. (HMI). In particularly, defect detection sensitivity, inspectability and damage to EUV mask were assessed. As conclusions, we found that the EBI system has capability to capture 16nm defects on 64nm absorber pattern EUV mask, satisfying the sensitivity requirement of 15nm NAND Flash HP node EUV mask. Furthermore, we confirmed there is no significant damage to susceptible Ru capped Mo/Si multilayer. We also identified that low throughput and high nuisance defect rate are critical challenges needed to address for the 16nm HP node EUV mask inspection. The high nuisance defect rate could be generated by poor LWR and stitching errors during EB writing

  11. Production of EUV mask blanks with low killer defects

    NASA Astrophysics Data System (ADS)

    Antohe, Alin O.; Kearney, Patrick; Godwin, Milton; He, Long; John Kadaksham, Arun; Goodwin, Frank; Weaver, Al; Hayes, Alan; Trigg, Steve

    2014-04-01

    For full commercialization, extreme ultraviolet lithography (EUVL) technology requires the availability of EUV mask blanks that are free of defects. This remains one of the main impediments to the implementation of EUV at the 22 nm node and beyond. Consensus is building that a few small defects can be mitigated during mask patterning, but defects over 100 nm (SiO2 equivalent) in size are considered potential "killer" defects or defects large enough that the mask blank would not be usable. The current defect performance of the ion beam sputter deposition (IBD) tool will be discussed and the progress achieved to date in the reduction of large size defects will be summarized, including a description of the main sources of defects and their composition.

  12. EUV mask reflectivity measurements with micro-scale spatial resolution

    SciTech Connect

    Goldberg, Kenneth A.; Rekawa, Senajith B.; Kemp, Charles D.; Barty, Anton; Anderson, Erik; Kearney, Patrick; Han, Hakseung

    2008-02-01

    The effort to produce defect-free mask blanks for EUV lithography relies on increasing the detection sensitivity of advanced mask inspection tools, operating at several wavelengths. They describe the unique measurement capabilities of a prototype actinic (EUV) wavelength microscope that is capable of detecting small defects and reflectivity changes that occur on the scale of microns to nanometers. The defects present in EUV masks can appear in many well-known forms: as particles that cause amplitude or phase variations in the reflected field; as surface contamination that reduces reflectivity and contrast; and as damage from inspection and use that reduces the reflectivity of the multilayer coating. This paper presents an overview of several topics where scanning actinic inspection makes a unique contribution to EUVL research. They describe the role of actinic scanning inspection in defect repair studies, observations of laser damage, actinic inspection following scanning electron microscopy, and the detection of both native and programmed defects.

  13. Properites of ultrathin films appropriate for optics capping layers in extreme ultraviolet lithography (EUVL)

    SciTech Connect

    Bajt, S; Edwards, N V; Madey, T E

    2007-06-25

    The contamination of optical surfaces by irradiation shortens optics lifetime and is one of the main concerns for optics used in conjunction with intense light sources, such as high power lasers, 3rd and 4th generation synchrotron sources or plasma sources used in extreme ultraviolet lithography (EUVL) tools. This paper focuses on properties and surface chemistry of different materials, which as thin layers, could be used as capping layers to protect and extend EUVL optics lifetime. The most promising candidates include single element materials such as ruthenium and rhodium, and oxides such as TiO{sub 2} and ZrO{sub 2}.

  14. Computer models for masked hearing experiments with beluga whales (Delphinapterus leucas).

    PubMed

    Erbe, C; King, A R; Yedlin, M; Farmer, D M

    1999-05-01

    Environmental assessments of manmade noise and its effects on marine mammals need to address the question of how noise interferes with animal vocalizations. Seeking the answer with animal experiments is very time consuming, costly, and often infeasible. This article examines the possibility of estimating results with software models. A matched filter, spectrogram cross-correlation, critical band cross-correlation, and a back-propagation neural network detected a beluga vocalization in three types of ocean noise. Performance was compared to masked hearing experiments with a beluga whale [C. Erbe and D. M. Farmer, Deep-Sea Res. II 45, 1373-1388 (1998)]. The artificial neural network simulated the animal data most closely and raised confidence in its ability to predict the interference of a variety of noise source with a variety of vocalizations. PMID:10335646

  15. A cocktail party model of spatial release from masking by both noise and speech interferers a)

    PubMed Central

    Jones, Gary L.; Litovsky, Ruth Y.

    2011-01-01

    A mathematical formula for estimating spatial release from masking (SRM) in a cocktail party environment would be useful as a simpler alternative to computationally intensive algorithms and may enhance understanding of underlying mechanisms. The experiment presented herein was designed to provide a strong test of a model that divides SRM into contributions of asymmetry and angular separation [Bronkhorst (2000). Acustica 86, 117–128] and to examine whether that model can be extended to include speech maskers. Across masker types the contribution to SRM of angular separation of maskers from the target was found to grow at a diminishing rate as angular separation increased within the frontal hemifield, contrary to predictions of the model. Speech maskers differed from noise maskers in the overall magnitude of SRM and in the contribution of angular separation (both greater for speech). These results were used to develop a modified model that achieved good fits to data for noise maskers (ρ = 0.93) and for speech maskers (ρ = 0.94) while using the same functions to describe separation and asymmetry components of SRM for both masker types. These findings suggest that this approach can be used to accurately model SRM for speech maskers in addition to primarily “energetic” noise maskers. PMID:21895087

  16. Investigating temporal asymmetry using masking period patterns and models of peripheral auditory processing.

    PubMed

    Lentz, Jennifer J; Shen, Yi

    2011-05-01

    Two experiments were conducted in conjunction with modeling to evaluate the role of peripheral nonlinearity and neural adaptation in the perception of temporally asymmetric sounds. In both experiments, maskers were broadband noises amplitude modulated with ramped and damped exponential modulators that repeated at 40 Hz. Masking period patterns (MPPs) were constructed by measuring detection threshold of a 5-ms, 1000-Hz tone burst as function of the signal's onset delay. Experiment I showed that varying modulator half-life from 1 to 16 ms led to differences in the damped and the ramped MPPs that were largest at the short half-lives and diminished at the longer half-lives. When masker level was varied (experiment II), the largest difference between ramped and damped MPPs occurred at moderate stimulus levels. Two peripheral auditory models were evaluated, one a simple auditory filter followed by a power-law nonlinearity and another, a model of auditory nerve processing [J. Acoust. Soc. Am. 126, 2390-2412 (2009)] that includes neural adaptation. Neither models predicted differences between the ramped and damped MPPs, providing indirect support that the central auditory system has a role in perceptual temporal asymmetry. PMID:21568421

  17. ON and OFF inhibition as mechanisms for forward masking in the inferior colliculus: a modeling study.

    PubMed

    Gai, Yan

    2016-06-01

    Masking effects of a preceding stimulus on the detection or perception of a signal have been found in several sensory systems in mammals, including humans and rodents. In the auditory system, it has been hypothesized that a central "OFF-inhibitory" mechanism, which is generated by neurons that respond after a sound is terminated, may contribute to the observed psychophysics. The present study constructed a systems model for the inferior colliculus that includes major ascending monaural and binaural auditory pathways. The fundamental characteristics of several neuron types along the pathways were captured by Hodgkin-Huxley models with specific membrane and synaptic properties. OFF responses were reproduced with a model of the superior paraolivary nucleus containing a hyperpolarization-activated h current and a T-type calcium current. When the gap between the end of the masker and the onset of the signal was large, e.g., >5 ms, OFF inhibition generated strong suppressive effects on the signal response. For smaller gaps, an additional inhibitory source, which was modeled as ON inhibition from the contralateral dorsal nucleus of the lateral lemniscus, showed the potential of explaining the psychophysics. Meanwhile, the effect of a forward masker on the binaural sensitivity to a low-frequency signal was examined, which was consistent with previous psychophysical findings related to sound localization. PMID:26912597

  18. Experimental study of particle-free mask handling

    NASA Astrophysics Data System (ADS)

    Amemiya, Mitsuaki; Ota, Kazuya; Taguchi, Takao; Suga, Osamu

    2009-03-01

    One of the critical issues for EUVL masks is clean and particle-free mask handling. We reported that the number of particle adders on the front side of a mask in the dual pod during the process from the load port to putting on the Electrostatic chuck (ESC) in vacuum could be reduce to less than 0.01 particle/cycle (>=46 nm). In addition, we found that chucking the mask on the ESC caused two serious issues. The first is that many particles stick to on the backside of the mask after chucking on the ESC, raising the question of whether the particle adders on the backside will travel to the front side. We examined the travel of these particles using the substrates after chucking and polystyrene latex (PSL) substrates that were dispersed on the backside. These experiments show that there is very little probability that particles on the backside will travel to the front side. The second issue is whether the mask blanks will charge up by chucking on the ESC and some particles will add on the front side. We measured the electric potential of the back and front sides of the mask and examined the particle adders. Our experiments revealed that to protect the mask from the particles, the mask must be grounded from the beginning to the end. For these two issues, we confirmed that a dual pod system works effectively to protect the mask from particles. This work is supported by NEDO as a part of the EUV mask program.

  19. Masked translation priming asymmetry in Chinese-English bilinguals: making sense of the Sense Model.

    PubMed

    Xia, Violet; Andrews, Sally

    2015-01-01

    Masked translation priming asymmetry is the robust finding that priming from a bilingual's first language (L1) to their second language (L2) is stronger than priming from L2 to L1. This asymmetry has been claimed to be task dependent. The Sense Model proposed by Finkbeiner, Forster, Nicol, and Nakamura (2004) claims that the asymmetry is reduced in semantic categorization relative to lexical decision due to a category filtering mechanism that limits the features considered in categorization decisions to dominant, category-relevant features. This paper reports two pairs of semantic categorization and lexical decision tasks designed to test the Sense Model's predictions. The experiments replicated the finding of Finkbeiner et al. that L2-L1 priming is somewhat stronger in semantic categorization than lexical decision, selectively for exemplars of the category. However, the direct comparison of L2-L1 and L1-L2 translation priming across tasks failed to confirm the Sense Model's central prediction that translation priming asymmetry is significantly reduced in semantic categorization. The data therefore fail to support the category filtering account of translation priming asymmetry. Rather, they suggest that pre-activation of conceptual features of the target category provides feedback to lexical forms that compensates for the weak connections between the lexical and conceptual representations of L2 words. PMID:25014131

  20. Masked target transform volume clutter metric for human observer visual search modeling

    NASA Astrophysics Data System (ADS)

    Moore, Richard Kirk

    The Night Vision and Electronic Sensors Directorate (NVESD) develops an imaging system performance model to aid in the design and comparison of imaging systems for military use. It is intended to approximate visual task performance for a typical human observer with an imaging system of specified optical, electrical, physical, and environmental parameters. When modeling search performance, the model currently uses only target size and target-to-background contrast to describe a scene. The presence or absence of other non-target objects and textures in the scene also affect search performance, but NVESD's targeting task performance metric based time limited search model (TTP/TLS) does not currently account for them explicitly. Non-target objects in a scene that impact search performance are referred to as clutter. A universally accepted mathematical definition of clutter does not yet exist. Researchers have proposed a number of clutter metrics based on very different methods, but none account for display geometry or the varying spatial frequency sensitivity of the human visual system. After a review of the NVESD search model, properties of the human visual system, and a literature review of clutter metrics, the new masked target transform volume clutter metric will be presented. Next the results of an experiment designed to show performance variation due to clutter alone will be presented. Then, the results of three separate perception experiments using real or realistic search imagery will be used to show that the new clutter metric better models human observer search performance than the current NVESD model or any of the reviewed clutter metrics.

  1. Neural masking by sub-threshold electric stimuli: animal and computer model results.

    PubMed

    Miller, Charles A; Woo, Jihwan; Abbas, Paul J; Hu, Ning; Robinson, Barbara K

    2011-04-01

    Electric stimuli can prosthetically excite auditory nerve fibers to partially restore sensory function to individuals impaired by profound or severe hearing loss. While basic response properties of electrically stimulated auditory nerve fibers (ANF) are known, responses to complex, time-changing stimuli used clinically are inadequately understood. We report that forward-masker pulse trains can enhance and reduce ANF responsiveness to subsequent stimuli and the novel observation that sub-threshold (nonspike-evoking) electric trains can reduce responsiveness to subsequent pulse-train stimuli. The effect is observed in the responses of cat ANFs and shown by a computational biophysical ANF model that simulates rate adaptation through integration of external potassium cation (K) channels. Both low-threshold (i.e., Klt) and high-threshold (Kht) channels were simulated at each node of Ranvier. Model versions without Klt channels did not produce the sub-threshold effect. These results suggest that some such accumulation mechanism, along with Klt channels, may underlie sub-threshold masking observed in cat ANF responses. As multichannel auditory prostheses typically present sub-threshold stimuli to various ANF subsets, there is clear relevance of these findings to clinical situations. PMID:21080206

  2. Extending models of visual-word recognition to semicursive scripts: Evidence from masked priming in Uyghur.

    PubMed

    Yakup, Mahire; Abliz, Wayit; Sereno, Joan; Perea, Manuel

    2015-12-01

    One basic feature of the Arabic script is its semicursive style: some letters are connected to the next, but others are not, as in the Uyghur word [see text]/ya xʃi/ ("good"). None of the current orthographic coding schemes in models of visual-word recognition, which were created for the Roman script, assign a differential role to the coding of within letter "chunks" and between letter "chunks" in words in the Arabic script. To examine how letter identity/position is coded at the earliest stages of word processing in the Arabic script, we conducted 2 masked priming lexical decision experiments in Uyghur, an agglutinative Turkic language. The target word was preceded by an identical prime, by a transposed-letter nonword prime (that either kept the ligation pattern or did not), or by a 2-letter replacement nonword prime. Transposed-letter primes were as effective as identity primes when the letter transposition in the prime kept the same ligation pattern as the target word (e.g., [see text]/inta_jin/-/itna_jin/), but not when the transposed-letter prime didn't keep the ligation pattern (e.g., [see text]/so_w_ʁa_t/-/so_ʁw_a_t/). Furthermore, replacement-letter primes were more effective when they kept the ligation pattern of the target word than when they did not (e.g., [see text]/so_d_ʧa_t/-/so_w_ʁa_t/ faster than [see text]/so_ʧd_a_t/-/so_w_ʁa_t/). We examined how input coding schemes could be extended to deal with the intricacies of semicursive scripts. PMID:26618626

  3. Printability and inspectability of defects on the EUV mask for sub-32nm half pitch HVM application

    NASA Astrophysics Data System (ADS)

    Huh, Sungmin; Kang, In-Yong; Kim, Sang-Hyun; Seo, Hwan-seok; Kim, Dongwan; Park, Jooon; Kim, Seong-Sue; Cho, Han-Ku; Goldberg, Kenneth; Mochi, Iacopo; Shoki, Tsutomu; Inderhees, Gregg

    2011-04-01

    The availability of defect-free masks remains one of the key challenges for inserting extreme ultraviolet lithography (EUVL) into high volume manufacturing, yet little data is available for understanding native defects on real masks. In this paper, a full field EUV mask is fabricated to see the printability of various defects on the mask. Programmed pit defect shows that minimum printable size of pits could be 17 nm of SEVD from the AIT. However 23.1nm in SEVD is printable from the EUV ADT. Defect printability and identification of its source along from blank fabrication to mask fabrication were studied using various inspection tools. Capture ratio of smallest printable defects was improved to 80% using optimized stack of metrical on wafer and state-of-art wafer inspection tool. Requirement of defect mitigation technology using fiducial mark are defined.

  4. Current status of NGL masks

    NASA Astrophysics Data System (ADS)

    Walker, David M.

    2000-07-01

    The manufacture of Next Generation Lithography reticles presents many challenges. Extremely small critical dimension and image placement error budgets; novel substrates including membranes and multi-layer reflective coatings; and inspection, detection and repair of subresolution defects will force revolutionary change in the infrastructure of mask technology. This paper surveys current NGL mask designs, structures, materials and manufacturing capabilities. Results from mask fabrication, physical modeling, error budget analysis and extensive experience in building X-Ray membrane masks are presented to develop process learning plans to meet future product specifications.

  5. Clay Mask Workshop

    ERIC Educational Resources Information Center

    Gamble, David L.

    2012-01-01

    Masks can represent so many things, such as emotions (happy, sad, fearful) and power. The familiar "comedy and tragedy" masks, derived from ancient Greek theater, are just one example from mask history. Death masks from the ancient Egyptians influenced the ancient Romans into creating similar masks for their departed. Masks can represent many…

  6. SEMATECH produces defect-free EUV mask blanks: defect yield and immediate challenges

    NASA Astrophysics Data System (ADS)

    Antohe, Alin O.; Balachandran, Dave; He, Long; Kearney, Patrick; Karumuri, Anil; Goodwin, Frank; Cummings, Kevin

    2015-03-01

    Availability of defect-free reflective mask has been one of the most critical challenges to extreme ultraviolet lithography (EUVL). To mitigate the risk, significant progress has been made on defect detection, pattern shifting, and defect repair. Clearly such mitigation strategies are based on the assumption that defect counts and sizes from incoming mask blanks must be below practical levels depending on mask specifics. The leading industry consensus for early mask product development is that there should be no defects greater than 80 nm in the quality area, 132 mm x 132 mm. In addition less than 10 defects smaller than 80 nm may be mitigable. SEMATECH has been focused on EUV mask blank defect reduction using Veeco Nexus TM IBD platform, the industry standard for mask blank production, and assessing if IBD technology can be evolved to a manufacturing solution. SEMATECH has recently announced a breakthrough reduction of defects in the mask blank deposition process resulting in the production of two defect-free EUV mask blanks at 54 nm inspection sensitivity (SiO2 equivalent). This paper will discuss the dramatic reduction of baseline EUV mask blank defects, review the current deposition process run and compare results with previous process runs. Likely causes of remaining defects will be discussed based on analyses as characterized by their compositions and whether defects are embedded in the multilayer stack or non-embedded.

  7. Smoke Mask

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Smoke inhalation injury from the noxious products of fire combustion accounts for as much as 80 percent of fire-related deaths in the United States. Many of these deaths are preventable. Smoke Mask, Inc. (SMI), of Myrtle Beach, South Carolina, is working to decrease these casualties with its line of life safety devices. The SMI personal escape hood and the Guardian Filtration System provide respiratory protection that enables people to escape from hazardous and unsafe conditions. The breathing filter technology utilized in the products is specifically designed to supply breathable air for 20 minutes. In emergencies, 20 minutes can mean the difference between life and death.

  8. EUV mask process development status for full field EUV exposure tool

    NASA Astrophysics Data System (ADS)

    Abe, Tsukasa; Adachi, Takashi; Akizuki, Hideo; Mohri, Hiroshi; Hayashi, Naoya; Ishikiriyama, Kosuke

    2008-05-01

    Extreme Ultra Violet Lithography (EUVL) is one of promising candidates for next generation lithography, 32nm node and beyond. Authors are developing EUV mask process targeting full field EUV exposure tool. Unlike the conventional optical mask, EUV mask is reflective type mask. To reflect 13.5nm wavelength light, 40 pairs of Mo/Si multilayer (ML) is used for reflective layer. Reflective layer is covered by capping layer. The capping layer protect reflective layer from absorber etching, defect repair and environmental condition. Top of absorber layer is covered by low reflective (LR) layer to achieve high contrast between the etched and not etched portion. Back side of EUV mask is covered by conductive film for electrostatic chuck use. In this paper, we will report current process development status of EUV mask for full field EUV exposure tool. Absorber patterning process including resist patterning and absorber etching were developed. Thin resist use and small resist damage dry etching process achieved pattern resolution of 32nm node. Defect inspection was also evaluated using DUV reticle inspection tool. Ta-based absorber on ruthenium (Ru) capped ML blanks was used for this evaluation. Because, Ru material has high resistivity to absorber etching plasma, it enable buffer layer less EUV mask structure. Ru also has better property on oxidation resistance compared to standard silicon (Si) capping layer.

  9. Dynamic mask for producing uniform or graded-thickness thin films

    DOEpatents

    Folta, James A.

    2006-06-13

    A method for producing single layer or multilayer films with high thickness uniformity or thickness gradients. The method utilizes a moving mask which blocks some of the flux from a sputter target or evaporation source before it deposits on a substrate. The velocity and position of the mask is computer controlled to precisely tailor the film thickness distribution. The method is applicable to any type of vapor deposition system, but is particularly useful for ion beam sputter deposition and evaporation deposition; and enables a high degree of uniformity for ion beam deposition, even for near-normal incidence of deposition species, which may be critical for producing low-defect multilayer coatings, such as required for masks for extreme ultraviolet lithography (EUVL). The mask can have a variety of shapes, from a simple solid paddle shape to a larger mask with a shaped hole through which the flux passes. The motion of the mask can be linear or rotational, and the mask can be moved to make single or multiple passes in front of the substrate per layer, and can pass completely or partially across the substrate.

  10. Development of a Model to Assess Masking Potential for Marine Mammals by the Use of Air Guns in Antarctic Waters.

    PubMed

    Wittekind, Dietrich; Tougaard, Jakob; Stilz, Peter; Dähne, Michael; Clark, Christopher W; Lucke, Klaus; von Benda-Beckmann, Sander; Ainslie, Michael A; Siebert, Ursula

    2016-01-01

    We estimated the long-range effects of air gun array noise on marine mammal communication ranges in the Southern Ocean. Air gun impulses are subject to significant distortion during propagation, potentially resulting in a quasi-continuous sound. Propagation modeling to estimate the received waveform was conducted. A leaky integrator was used as a hearing model to assess communication masking in three species due to intermittent/continuous air gun sounds. Air gun noise is most probably changing from impulse to continuous noise between 1,000 and 2,000 km from the source, leading to a reduced communication range for, e.g., blue and fin whales up to 2,000 km from the source. PMID:26611093

  11. Novel non-chemically amplified (n-CARs) negative resists for EUVL

    NASA Astrophysics Data System (ADS)

    Singh, Vikram; Satyanarayana, V. S. V.; Sharma, Satinder K.; Ghosh, Subrata; Gonsalves, Kenneth E.

    2014-03-01

    We report the lithography performance of novel non chemical amplified (n-CARS) negative photoresist materials which are accomplished by homopolymers and copolymers that are prepared from monomers containing sulfonium groups. The latter have long been found to be sensitive to UV radiation and undergo polarity change on exposure. For this reason, these groups were chosen as radiation sensitive groups in non- CARs that are discussed herein. Novel n-CAR negative resists were synthesized and characterized for EUVL applications, as they are directly sensitive to radiation without utilizing the concept of chemical amplification. The n-CARs achieved 20 and 16 nm L/2S, L/S patterns to meet the ITRS requirements. We will also discuss the sensitivity and LER of these negative n-CARS to e-beam irradiation which will provide a basis for EUVL down to the 16 nm node and below. These new negative tone resist provide a viable path forward for designing non- chemically amplified resists that can obtain higher resolutions than current chemically amplified resists at competitive sensitivities.

  12. Masks and Other Disguises.

    ERIC Educational Resources Information Center

    Ploghoft, Debra

    Instructions for making simple masks are provided in this guide for teachers of elementary children. Directions with illustrations are given for constructing masks from paper plates, construction paper, plastic milk jugs, and papier-mache. Ideas include a clown mask, a flower mask, a top hat, a paper crown, and "Groucho" glasses. Types of masks…

  13. A consistent NPMLE of the joint distribution function with competing risks data under the dependent masking and right-censoring model.

    PubMed

    Li, Jiahui; Yu, Qiqing

    2016-01-01

    Dinse (Biometrics, 38:417-431, 1982) provides a special type of right-censored and masked competing risks data and proposes a non-parametric maximum likelihood estimator (NPMLE) and a pseudo MLE of the joint distribution function [Formula: see text] with such data. However, their asymptotic properties have not been studied so far. Under the extention of either the conditional masking probability (CMP) model or the random partition masking (RPM) model (Yu and Li, J Nonparametr Stat 24:753-764, 2012), we show that (1) Dinse's estimators are consistent if [Formula: see text] takes on finitely many values and each point in the support set of [Formula: see text] can be observed; (2) if the failure time is continuous, the NPMLE is not uniquely determined, and the standard approach (which puts weights only on one element in each observed set) leads to an inconsistent NPMLE; (3) in general, Dinse's estimators are not consistent even under the discrete assumption; (4) we construct a consistent NPMLE. The consistency is given under a new model called dependent masking and right-censoring model. The CMP model and the RPM model are indeed special cases of the new model. We compare our estimator to Dinse's estimators through simulation and real data. Simulation study indicates that the consistent NPMLE is a good approximation to the underlying distribution for moderate sample sizes. PMID:25160694

  14. Challenges in constructing EUV metrology tools to qualify the EUV masks for HVM implementation

    NASA Astrophysics Data System (ADS)

    Houser, David C.; Dong, Feng; Perera, Chami N.; Perera, Rupert C. C.

    2015-09-01

    Extreme Ultraviolet (EUV) Lithography is still viewed as the most promising approach for maintaining the pace of Moore's Law. Recent real achievements in EUV Lithography (EUVL) have encouraged semiconductor manufacturers to reconsider their road maps. One of the principal challenges in the ongoing EUVL implementation for high volume manufacturing (HVM) is the availability of necessary clean at wavelength metrology tools. EUV Tech is the world's leading manufacturer of at-wavelength EUV metrology equipment. Founded in 1997, EUV Tech has pioneered the development of several stand-alone inspection, metrology, and calibration tools for EUV lithographic applications that can be operated in a clean room environment on the floor of a fab. In this paper, EUV Tech's R&D program to minimize particle adders in our EUV Reflectometer along with the ongoing effort to enhance the reflectivity and wavelength, precision and accuracy required to qualify the EUV masks for HVM. In addition to preliminary results from our stand alone EUV Scatterometer developed to characterize the phase roughness of a EUV mask and the introduction of EUV Tech's Pellicle test suite for testing EUV pellicles.

  15. History and future of mask making

    NASA Astrophysics Data System (ADS)

    Levy, Ken L.

    1996-12-01

    The history of the mask industry has three main periods, which I call the Classical Period, the Dark Ages, and the Renaissance, by analogy with those periods in the history of Western Europe. During the Classical Period, people developed 1X masks and the technology to make them. In the Dark Ages, people exploited the equipment developed during the Classical Period to make 5X reduction reticle, ending the nobility of mask making. In today's Renaissance of mask making, a proliferation of mask types is requiring a rebirth of innovation and creativity. The Renaissance resembles the Classical Period: masks are once again strategic, and technological capability is once again the driver. Meanwhile, the mask industry is carrying forward the productivity and efficiency gains it achieved during the Dark Ages. We must create a new business and economic model to support these changes in the characteristics of the marketplace.

  16. Improving Approaches for Determining Ice Volume Change on the Greenland Ice Sheet Margin using ASTER and SPOT Digital Elevation Models and Spectral Masking

    NASA Astrophysics Data System (ADS)

    Johnson, K. N.; Rhodes, T.; Tulaczyk, S. M.; Finfrock, A.; Lajoie, L.

    2009-12-01

    The Greenland Ice Sheet (GIS) is the largest ice sheet in the Northern Hemisphere and understanding trends in its mass balance has important implications for predicting global sea level rise. High relief topography along the margin of the GIS makes it difficult to use low-resolution remote sensing to resolve ice elevations. These marginal regions however, tend to be more dynamic than the interior of the ice sheet and may show signs of ice volume loss earlier than the interior. In this study we difference georeferenced ASTER digital elevation models (DEMs) from 2000-01 (30 meter resolution) with SPOT DEMs from 2008-09 (40 meter resolution) made available through the SPIRIT IPY program. ASTER DEMs from 2006-07 are used where SPOT data is not available. The change in these DEMs is divided by the time elapsed between scenes giving change in km3 per year. The method used for DEM production is not accurate over low contrast surfaces such as water, and snow. High relief bedrock can also have more error than areas of glacial ice due to slope. Masking snow, water, and rock from scenes minimizes total error. Most methods of spectral masking available in the literature rely on establishing thresholds for a scene which separate snow from ice from water. In order to apply these methods to multiple scenes taken at different latitudes, seasons, and sun altitudes, a new set of thresholds need to be developed for each scene which proves to be a very time intensive process. When covering large areas with a mosaic of scenes, these methods have not proven applicable. We have developed a method of nesting masks which allows for faster and less subjective trial-and-error threshold setting. This method can be applied to a range of scenes with little to no individual manipulation giving a repeatable result. The first mask eliminates most bedrock with a negative NDSI and fjord water and sea ice with an elevation of about 0. A principal components analysis (PCA) is done under this mask for

  17. Wavelength dependent mask defects

    NASA Astrophysics Data System (ADS)

    Badger, Karen; Butt, Shahid; Burnham, Jay; Faure, Tom; Hibbs, Michael; Rankin, Jed; Thibault, David; Watts, Andrew

    2005-05-01

    For years there has been a mismatch between the photomask inspection wavelength and the usage conditions. While the non-actinic inspection has been a source for concern, there has been essentially no evidence that a defect "escaped" the mask production process due to the inspection mismatch. This paper will describe the discovery of one such defect, as well as the diagnostic and inspection techniques used to identify the location, analyze the composition, and determine the source of the printed wafer defect. Conventional mask inspection techniques revealed no defects, however an actinic Aerial Image Metrology System (AIMS) revealed a 1.5 mm region on the mask with up to 59% transmission reduction at 193 nm. Further diagnostics demonstrated a strong wavelength dependence which accounted for the near invisibility of the defect at I line (365 nm) or even DUV (248 nm) wavelengths, which had 0% and 5% respective transmission reductions. Using some creative imaging techniques via AIMS tool and modeling, the defect was deduced to have a three dimensional Gaussian absorption character, with total width approximately 1.5 mm. Several non-destructive diagnostic techniques were developed to determine the composition and location of the defect within the substrate. These results will be described in addition to identifying methods for ensuring product quality in the absence of actinic inspection.

  18. Development of core technologies on EUV mask and resist for sub-20-nm half pitch generation

    NASA Astrophysics Data System (ADS)

    Inoue, Soichi; Amano, Tsuyoshi; Itani, Toshiro; Watanabe, Hidehiro; Mori, Ichiro; Watanabe, Takeo; Kinoshita, Hiroo; Miyai, Hiroki; Hatakeyama, Masahiro

    2012-09-01

    This paper reports on the current status for the key infrastructures of the extreme ultraviolet lithography (EUVL) for sub-20-nm half pitch (hp) generation. More specifically, the inspection technologies for EUV mask and resist-related technologies will be dedicatedly discussed. First, the actinic blank inspector is strongly required especially for sub-20-nm hp generation. The basic configuration of the prototyping tool will be presented. Second, the basic configuration of the newly developing patterned mask inspector (PMI) consisting of the projection-type optics for the electron beam (EB) will be presented. The primary challenge for the EUV resist is the concurrent improvements of resolution, line width roughness, sensitivity, and outgas. The basic performance of the EUV resist and preliminary validation of the outgas qualification for sub-20-nm hp will be presented.

  19. Damage/organic free ozonated DI water cleaning on EUVL Ru capping layer

    NASA Astrophysics Data System (ADS)

    Lee, Seung-ho; Kang, Bong-kyun; Kim, Hyuk-min; Kim, Min-soo; Cho, Han-ku; Jeon, Chan-uk; Ko, Hyung-ho; Lee, Han-shin; Ahn, Jin-ho; Park, Jin-Goo

    2010-09-01

    The adaption of EUVL requires the development of new cleaning method for the removal of new contaminant without surface damage. One of the harsh contaminants is the carbon contamination generated during EUV exposure. This highly dense organic contaminant is hardly removed by conventional SPM solution on Ru capped Mo/Si multilayer. The hopeful candidate for this removal is ozonated water (DIO3), which is not only well-known strong oxidizer but also environmentally friendly solution. However, this solution might cause some damage to the Ru capping layer mostly depending on its concentration. For these reasons, DIO3 cleaning solutions, which are generated with various additive gases, were characterized to understand the correlation between DIO3 concentration and damages on 2.5 nm thick ruthenium (Ru) surface. An optimized DIO3 generation method and cleaning condition were developed with reduced surface damage. These phenomena were explained by electrochemical reaction.

  20. Shuttle mask floorplanning

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Tian, Ruiqi; Wong, Martin D.; Reich, Alfred J.

    2003-12-01

    A shuttle mask has different chips on the same mask. The chips are not electrically connected. Alliance and foundry customers can utilize shuttle masks to share the rising cost of mask and wafer manufacturing. This paper studies the shuttle mask floorplan problem, which is formulated as a rectangle-packing problem with constraints of final die sawing strategy and die-to-die mask inspection. For our formulation, we offer a "merging" method that reduces the problem to an unconstrained slicing floorplan problem. Excellent results are obtained from the experiment with real industry data. We also study a "general" method and discuss the reason why it does not work very well.

  1. Image-based pupil plane characterization via principal component analysis for EUVL tools

    NASA Astrophysics Data System (ADS)

    Levinson, Zac; Burbine, Andrew; Verduijn, Erik; Wood, Obert; Mangat, Pawitter; Goldberg, Kenneth A.; Benk, Markus P.; Wojdyla, Antoine; Smith, Bruce W.

    2016-03-01

    We present an approach to image-based pupil plane amplitude and phase characterization using models built with principal component analysis (PCA). PCA is a statistical technique to identify the directions of highest variation (principal components) in a high-dimensional dataset. A polynomial model is constructed between the principal components of through-focus intensity for the chosen binary mask targets and pupil amplitude or phase variation. This method separates model building and pupil characterization into two distinct steps, thus enabling rapid pupil characterization following data collection. The pupil plane variation of a zone-plate lens from the Semiconductor High-NA Actinic Reticle Review Project (SHARP) at Lawrence Berkeley National Laboratory will be examined using this method. Results will be compared to pupil plane characterization using a previously proposed methodology where inverse solutions are obtained through an iterative process involving least-squares regression.

  2. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  3. Mask degradation monitoring with aerial mask inspector

    NASA Astrophysics Data System (ADS)

    Tseng, Wen-Jui; Fu, Yung-Ying; Lu, Shih-Ping; Jiang, Ming-Sian; Lin, Jeffrey; Wu, Clare; Lifschitz, Sivan; Tam, Aviram

    2013-06-01

    As design rule continues to shrink, microlithography is becoming more challenging and the photomasks need to comply with high scanner laser energy, low CDU, and ever more aggressive RETs. This give rise to numerous challenges in the semiconductor wafer fabrication plants. Some of these challenges being contamination (mainly haze and particles), mask pattern degradation (MoSi oxidation, chrome migration, etc.) and pellicle degradation. Fabs are constantly working to establish an efficient methodology to manage these challenges mainly using mask inspection, wafer inspection, SEM review and CD SEMs. Aerial technology offers a unique opportunity to address the above mask related challenges using one tool. The Applied Materials Aera3TM system has the inherent ability to inspect for defects (haze, particles, etc.), and track mask degradation (e.g. CDU). This paper focuses on haze monitoring, which is still a significant challenge in semiconductor manufacturing, and mask degradation effects that are starting to emerge as the next challenge for high volume semiconductor manufacturers. The paper describes Aerial inspector (Aera3) early haze methodology and mask degradation tracking related to high volume manufacturing. These will be demonstrated on memory products. At the end of the paper we take a brief look on subsequent work currently conducted on the more general issue of photo mask degradation monitoring by means of an Aerial inspector.

  4. LER control and mitigation: mask roughness induced LER

    SciTech Connect

    McClinton, Brittany; Naulleau, Patrick

    2011-02-21

    In the push towards commercialization of extreme-ultraviolet lithography (EUVL), meeting the stringent requirements for line-edge roughness (LER) is increasingly challenging. For the 22-nm half-pitch node and below, the ITRS requires under 1.2 nm LER. Much of this LER is thought to arise from three significant contributors: LER on the mask absorber pattern, LER from the resist, and LER from mask roughness induced speckle. The physical mechanism behind the last contributor is becoming clearer, but how it is affected by the presence of aberrations is less well understood. Here, we conduct a full 2D aerial image simulation analysis of aberrations sensitivities of mask roughness induced LER for the first 37 fringe zernikes. These results serve as a guideline for future LER aberrations control. In examining how to mitigate mask roughness induced LER, we next consider an alternate illumination scheme whereby a traditional dipole's angular spectrum is extended in the direction parallel to the line-and-space mask absorber pattern to represent a 'strip'. While this illumination surprisingly provides merely minimal improvement to the LER as several alternate illumination schemes, overall imaging quality in terms of ILS, NILS, and contrast is improved. While the 22-nm half-pitch node can tolerate significant aberrations from a mask roughness induced LER perspective, total aberration levels for the 16-nm half-pitch node need to be strictly capped at 0.25nm rms to meet the ITRS guidelines. An individual aberrations study for the first 37 fringe zernikes on the 16-nm half-pitch node at the 0.25nm rms level reveals a sensitivity to various forms of spherical aberrations (Z9 & Z25) and quadrafoil (Z28) in particular, under conventional crosspole illumination ({sigma} = 0.10). Compared to conventional dipole or crosspole illuminations, an extended dipole 'strip' illumination scheme offers a way to mitigate mask roughness induced LER, while still maintaining high imaging quality for

  5. Detecting Drawdowns Masked by Environmental Stresses with Water-Level Models

    PubMed Central

    Garcia, CA; Halford, KJ; Fenelon, JM

    2013-01-01

    Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period. PMID:23469925

  6. Cognitive Development Masks Support for Attributional Style Models of Depression in Children and Adolescents

    ERIC Educational Resources Information Center

    Weitlauf, Amy S.; Cole, David A.

    2012-01-01

    Attributional style models of depression in adults (Abramson et al. 1989, 1978) have been adapted for use with children; however, most applications do not consider that children's understanding of causal relations may be qualitatively different from that of adults. If children's causal attributions depend on children's level of cognitive…

  7. Wafer topography modeling for ionic implantation mask correction dedicated to 2x nm FDSOI technologies

    NASA Astrophysics Data System (ADS)

    Michel, Jean-Christophe; Le Denmat, Jean-Christophe; Sungauer, Elodie; Robert, Frédéric; Yesilada, Emek; Armeanu, Ana-Maria; Entradas, Jorge; Sturtevant, John L.; Do, Thuy; Granik, Yuri

    2013-04-01

    Reflection by wafer topography and underlying layers during optical lithography can cause unwanted exposure in the resist [1]. This wafer stack effect phenomenon which is neglected for larger nodes than 45nm, is becoming problematic for 32nm technology node and below at the ionic implantation process. This phenomenon is expected to be attenuated by the use of anti-reflecting coating but increases process complexity and adds cost and cycle time penalty. As a consequence, an OPC based solution is today under evaluation to cope with stack effects involved in ionic implantation patterning [2] [3]. For the source drain (SD) ionic implantation process step on 28nm Fully Depleted Silicon-on-Insulator (FDSOI) technology, active silicon areas, poly silicon patterns, Shallow Trench Isolation (STI), Silicon-on-Insulator (SOI) areas and the transitions between these different regions result in significant SD implant pattern critical dimension variations. The large number of stack variations involved in these effects implies a complex modeling to simulate pattern degradations. This paper deals with the characterization of stack effects on 28nm node using SOI substrates. The large number of measurements allows to highlight all individual and combined stack effects. A new modeling flow has been developed in order to generate wafer stack aware OPC model. The accuracy and the prediction of the model is presented in this paper.

  8. Detecting drawdowns masked by environmental stresses with water-level models

    USGS Publications Warehouse

    Garcia, C.A.; Halford, K.J.; Fenelon, J.M.

    2013-01-01

    Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period.

  9. Using synchrotron light to accelerate EUV resist and mask materials learning

    NASA Astrophysics Data System (ADS)

    Naulleau, Patrick; Anderson, Christopher N.; Baclea-an, Lorie-Mae; Denham, Paul; George, Simi; Goldberg, Kenneth A.; Jones, Gideon; McClinton, Brittany; Miyakawa, Ryan; Mochi, Iacopo; Montgomery, Warren; Rekawa, Seno; Wallow, Tom

    2011-03-01

    As commercialization of extreme ultraviolet lithography (EUVL) progresses, direct industry activities are being focused on near term concerns. The question of long term extendibility of EUVL, however, remains crucial given the magnitude of the investments yet required to make EUVL a reality. Extendibility questions are best addressed using advanced research tools such as the SEMATECH Berkeley microfield exposure tool (MET) and actinic inspection tool (AIT). Utilizing Lawrence Berkeley National Laboratory's Advanced Light Source facility as the light source, these tools benefit from the unique properties of synchrotron light enabling research at nodes generations ahead of what is possible with commercial tools. The MET for example uses extremely bright undulator radiation to enable a lossless fully programmable coherence illuminator. Using such a system, resolution enhancing illuminations achieving k1 factors of 0.25 can readily be attained. Given the MET numerical aperture of 0.3, this translates to an ultimate resolution capability of 12 nm. Using such methods, the SEMATECH Berkeley MET has demonstrated resolution in resist to 16-nm half pitch and below in an imageable spin-on hard mask. At a half pitch of 16 nm, this material achieves a line-edge roughness of 2 nm with a correlation length of 6 nm. These new results demonstrate that the observed stall in ultimate resolution progress in chemically amplified resists is a materials issue rather than a tool limitation. With a resolution limit of 20-22 nm, the CAR champion from 2008 remains as the highest performing CAR tested to date. To enable continued advanced learning in EUV resists, SEMATECH has initiated a plan to implement a 0.5 NA microfield tool at the Advanced Light Source synchrotron facility. This tool will be capable of printing down to 8-nm half pitch.

  10. Mask industry assessment: 2004

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert V.; Hector, Scott D.

    2004-12-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the third in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey builds upon the 2003 survey to provide an ongoing database using the same questions as a baseline with only a few minor changes or additions. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from ten major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market.

  11. 2013 mask industry survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt

    2013-09-01

    A comprehensive survey was sent to merchant and captive mask shops to gather information about the mask industry as an objective assessment of its overall condition. 2013 marks the 12th consecutive year for this process. Historical topics including general mask profile, mask processing, data and write time, yield and yield loss, delivery times, maintenance, and returns were included and new topics were added. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. While each year's survey includes minor updates based on feedback from past years and the need to collect additional data on key topics, the bulk of the survey and reporting structure have remained relatively constant. A series of improvements is being phased in beginning in 2013 to add value to a wider audience, while at the same time retaining the historical content required for trend analyses of the traditional metrics. Additions in 2013 include topics such as top challenges, future concerns, and additional details in key aspects of mask masking, such as the number of masks per mask set per ground rule, minimum mask resolution shipped, and yield by ground rule. These expansions beyond the historical topics are aimed at identifying common issues, gaps, and needs. They will also provide a better understanding of real-life mask requirements and capabilities for comparison to the International Technology Roadmap for Semiconductors (ITRS).

  12. Study on modeling of resist heating effect correction in EB mask writer EBM-9000

    NASA Astrophysics Data System (ADS)

    Nomura, Haruyuki; Kamikubo, Takashi; Suganuma, Mizuna; Kato, Yasuo; Yashima, Jun; Nakayamada, Noriaki; Anze, Hirohito; Ogasawara, Munehiro

    2015-07-01

    Resist heating effect which is caused in electron beam lithography by rise in substrate temperature of a few tens or hundreds of degrees changes resist sensitivity and leads to degradation of local critical dimension uniformity (LCDU). Increasing writing pass count and reducing dose per pass is one way to avoid the resist heating effect, but it worsens writing throughput. As an alternative way, NuFlare Technology is developing a heating effect correction system which corrects CD deviation induced by resist heating effect and mitigates LCDU degradation even in high dose per pass conditions. Our developing correction model is based on a dose modulation method. Therefore, a kind of conversion equation to modify the dose corresponding to CD change by temperature rise is necessary. For this purpose, a CD variation model depending on local pattern density was introduced and its validity was confirmed by experiments and temperature simulations. And then the dose modulation rate which is a parameter to be used in the heating effect correction system was defined as ideally irrelevant to the local pattern density, and the actual values were also determined with the experimental results for several resist types. The accuracy of the heating effect correction was also discussed. Even when deviations depending on the pattern density slightly remains in the dose modulation rates (i.e., not ideal in actual), the estimated residual errors in the correction are sufficiently small and acceptable for practical 2 pass writing with the constant dose modulation rates. In these results, it is demonstrated that the CD variation model is effective for the heating effect correction system.

  13. Validity of the thin mask approximation in extreme ultraviolet mask roughness simulations

    SciTech Connect

    Naulleau, Patrick; George, Simi

    2011-01-26

    In the case of extreme ultraviolet (EUV) lithography, modeling has shown that reflector phase roughness on the lithographic mask is a significant concern due to the image plan speckle it causes and the resulting line-edge roughness on imaged features. Modeling results have recently been used to determine the requirements for future production worthy masks yielding the extremely stringent specification of 50 pm rms roughness. Owing to the scale of the problem in terms of memory requirements, past modeling results have all been based on the thin mask approximation. EUV masks, however, are inherently three dimensional in nature and thus the question arises as to the validity of the thin mask approximation. Here we directly compare image plane speckle calculation results using the fast two dimensional thin mask model to rigorous finite-difference time-domain results and find the two methods to be comparable.

  14. Investigating the intrinsic cleanliness of automated handling designed for EUV mask pod-in-pod systems

    NASA Astrophysics Data System (ADS)

    Brux, O.; van der Walle, P.; van der Donck, J. C. J.; Dress, P.

    2011-11-01

    Extreme Ultraviolet Lithography (EUVL) is the most promising solution for technology nodes 16nm (hp) and below. However, several unique EUV mask challenges must be resolved for a successful launch of the technology into the market. Uncontrolled introduction of particles and/or contamination into the EUV scanner significantly increases the risk for device yield loss and potentially scanner down-time. With the absence of a pellicle to protect the surface of the EUV mask, a zero particle adder regime between final clean and the point-of-exposure is critical for the active areas of the mask. A Dual Pod concept for handling EUV masks had been proposed by the industry as means to minimize the risk of mask contamination during transport and storage. SuSS-HamaTech introduces MaskTrackPro InSync as a fully automated solution for the handling of EUV masks in and out of this Dual Pod System and therefore constitutes an interface between various tools inside the Fab. The intrinsic cleanliness of each individual handling and storage step of the inner shell (EIP) of this Dual Pod and the EUV mask inside the InSync Tool has been investigated to confirm the capability for minimizing the risk of cross-contamination. An Entegris Dual Pod EUV-1000A-A110 has been used for the qualification. The particle detection for the qualification procedure was executed with the TNO's RapidNano Particle Scanner, qualified for particle sizes down to 50nm (PSL equivalent). It has been shown that the target specification of < 2 particles @ 60nm per 25 cycles has been achieved. In case where added particles were measured, the EIP has been identified as a potential root cause for Ni particle generation. Any direct Ni-Al contact has to be avoided to mitigate the risk of material abrasion.

  15. Actinic detection of multilayer defects on EUV mask blanks using LPP light source and dark-field imaging

    NASA Astrophysics Data System (ADS)

    Tezuka, Yoshihiro; Ito, Masaaki; Terasawa, Tsuneo; Tomie, Toshihisa

    2004-05-01

    The development of defect-free mask blanks including inspection is one of the big challenges for the implementation of extreme ultraviolet lithography (EUVL), especially when the introduction of EUVL is rescheduled to a later technology node. Among others, inspection of multilayer coated mask blanks with no oversight of critical defects and with minimal detection of false defects is a challenging issue for providing mask blanks free of defects or with thorough characterization of any existing defects. MIRAI Project has been developing a novel actinic (at-wavelength) inspection tool for detecting critical multilayer defects using a dark-field imaging and a laser-produced plasma (LPP) light source, expecting better sensitivity and better correlation with printability. The first experimental set up is completed for proof-of-concept (POC) demonstration using 20x Schwarzschild imaging optics and a backsideilluminated CCD. An in-house LPP light source is integrated to optimally illuminate the area of interest by EUV with a wavelength of 13.5nm. For its illuminator, a multilayer-coated elliptical mirror is used to illuminate a mask blank with the EUV that is collected within a wide solid angle from the light source. The first EUV dark-field image is obtained from a mask blank with programmed multilayer defects which are manufactured by locating well-defined patterns before depositing Mo/Si multilayer on EUV mask substrate. All the fabricated multilayer defects down to 70nm in width and 3.5nm in height are detected as clear signals that are distinguishable from the background intensity arising from the scattering by the surface roughness of the multilayer-coated mask blank. We have also detected a phase defect as low as 2nm in height. False defect count was not only zero within the area of view but also statistically confirmed to be less than one within the whole area of a mask blank assuming the extrapolation of observed fluctuation of background intensity is applicable

  16. Mask characterization for CDU budget breakdown in advanced EUV lithography

    NASA Astrophysics Data System (ADS)

    Nikolsky, Peter; Strolenberg, Chris; Nielsen, Rasmus; Nooitgedacht, Tjitte; Davydova, Natalia; Yang, Greg; Lee, Shawn; Park, Chang-Min; Kim, Insung; Yeo, Jeong-Ho

    2012-11-01

    As the ITRS Critical Dimension Uniformity (CDU) specification shrinks, semiconductor companies need to maintain a high yield of good wafers per day and a high performance (and hence market value) of finished products. This cannot be achieved without continuous analysis and improvement of on-product CDU as one of the main drivers for process control and optimization with better understanding of main contributors from the litho cluster: mask, process, metrology and scanner. In this paper we will demonstrate a study of mask CDU characterization and its impact on CDU Budget Breakdown (CDU BB) performed for an advanced EUV lithography with 1D and 2D feature cases. We will show that this CDU contributor is one of the main differentiators between well-known ArFi and new EUV CDU budgeting principles. We found that reticle contribution to intrafield CDU should be characterized in a specific way: mask absorber thickness fingerprints play a role comparable with reticle CDU in the total reticle part of the CDU budget. Wafer CD fingerprints, introduced by this contributor, may or may not compensate variations of mask CD's and hence influence on total mask impact on intrafield CDU at the wafer level. This will be shown on 1D and 2D feature examples in this paper. Also mask stack reflectivity variations should be taken into account: these fingerprints have visible impact on intrafield CDs at the wafer level and should be considered as another contributor to the reticle part of EUV CDU budget. We observed also MEEF-through-field fingerprints in the studied EUV cases. Variations of MEEF may also play a role for the total intrafield CDU and may be taken into account for EUV Lithography. We characterized MEEF-through-field for the reviewed features, the results to be discussed in our paper, but further analysis of this phenomenon is required. This comprehensive approach to characterization of the mask part of EUV CDU characterization delivers an accurate and integral CDU Budget

  17. Psychometric functions for informational masking

    NASA Astrophysics Data System (ADS)

    Lutfi, Robert A.; Kistler, Doris J.; Callahan, Michael R.; Wightman, Frederic L.

    2003-12-01

    The term informational masking has traditionally been used to refer to elevations in signal threshold resulting from masker uncertainty. In the present study, the method of constant stimuli was used to obtain complete psychometric functions (PFs) from 44 normal-hearing listeners in conditions known to produce varying amounts of informational masking. The listener's task was to detect a pure-tone signal in the presence of a broadband noise masker (low masker uncertainty) and in the presence of multitone maskers with frequencies and amplitudes that varied at random from one presentation to the next (high masker uncertainty). Relative to the broadband noise condition, significant reductions were observed in both the slope and the upper asymptote of the PF for multitone maskers producing large amounts of informational masking. Slope was affected more for some listeners and conditions while asymptote was affected more for others; consequently, neither parameter alone was highly predictive of individual thresholds or the amount of informational masking. Mean slopes and asymptotes varied nonmonotonically with the number of masker components in a manner similar to mean thresholds, particularly when the estimated effect of energetic masking on thresholds was subtracted out. As in past studies, the threshold data were well described by a model in which trial-by-trial judgments are based on a weighted sum of levels in dB at the output of independent auditory filters. The psychometric data, however, complicated the model's interpretation in two ways: First, they suggested that, depending on the listener and condition, the weights can either reflect a fixed influence of masker components on each trial or the effect of occasionally mistaking a masker component for the signal from trial to trial. Second, they indicated that in either case the variance of the underlying decision variable as estimated from PF slope is not by itself great enough to account for the observed changes

  18. Mask industry assessment: 2003

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2003-12-01

    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was initiated in 2002 with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition.1 This paper presents the results of the second annual survey which is an enhanced version of the inaugural survey building upon its strengths and improving the weak points. The original survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. The assessment is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the critical mask industry. An objective is to create a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. As subsequent years are added, historical profiles can also be created. This assessment includes inputs from ten major global merchant and captive mask manufacturers representing approximately 80% of the global mask market (using revenue as the measure) and making this the most comprehensive mask industry survey ever. The participating companies are: Compugraphics, Dai Nippon Printing, Dupont Photomask, Hoya, IBM, Infineon, Intel, Taiwan Mask Company, Toppan, and TSMC. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the mask industry.

  19. Object Substitution Masking: When Does Mask Preview Work?

    ERIC Educational Resources Information Center

    Lim, Stephen Wee Hun; Chua, Fook K.

    2008-01-01

    When a target is enclosed by a 4-dot mask that persists after the target disappears, target identification is worse than it is when the mask terminates with the target. This masking effect is attributed to object substitution masking (OSM). Previewing the mask, however, attenuates OSM. This study investigated specific conditions under which mask…

  20. Iso-sciatic point: novel approach to distinguish shadowing 3-D mask effects from scanner aberrations in extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Leunissen, Leonardus H. A.; Gronheid, Roel; Gao, Weimin

    2006-06-01

    Extreme ultraviolet lithography (EUVL) uses a reflective mask with a multilayer coating. Therefore, the illumination is an off-axis ring field system that is non-telecentric on the mask side. This non-zero angle of incidence combined with the three-dimensional mask topography results in the so-called "shadowing effect". The shadowing causes the printed CD to depend on the orientation as well as on the position in the slit and it will significantly influence the image formation [1,2]. In addition, simulations show that the Bossung curves are asymmetrical due to 3-D mask effects and their best focus depends on the shadowing angle [3]. Such tilts in the Bossung curves are usually associated with aberrations in the optical system. In this paper, we describe an approach in which both properties can be disentangled. Bossung curve simulations with varying effective angles of incidence (between 0 and 6 degrees) show that at discrete defocus offsets, the printed linewidth is independent of the incident angle (and thus independent of the shadowing effect), the so-called iso-sciatic (constant shadowing) point. For an ideal optical system this means that the size of a printed feature with a given mask-CD and orientation does not change through slit. With a suitable test structure it is possible to use this effect to distinguish between mask topography and imaging effects from aberrations through slit. Simulations for the following aberrations tested the approach: spherical, coma and astigmatism.

  1. Fast mask writers: technology options and considerations

    NASA Astrophysics Data System (ADS)

    Litt, Lloyd C.; Groves, Timothy; Hughes, Greg

    2011-04-01

    The semiconductor industry is under constant pressure to reduce production costs even as the complexity of technology increases. Lithography represents the most expensive process due to its high capital equipment costs and the implementation of low-k1 lithographic processes, which have added to the complexity of making masks because of the greater use of optical proximity correction, pixelated masks, and double or triple patterning. Each of these mask technologies allows the production of semiconductors at future nodes while extending the utility of current immersion tools. Low-k1 patterning complexity combined with increased data due to smaller feature sizes is driving extremely long mask write times. While a majority of the industry is willing to accept times of up to 24 hours, evidence suggests that the write times for many masks at the 22 nm node and beyond will be significantly longer. It has been estimated that funding on the order of 50M to 90M for non-recurring engineering (NRE) costs will be required to develop a multiple beam mask writer system, yet the business case to recover this kind of investment is not strong. Moreover, funding such a development poses a high risk for an individual supplier. The structure of the mask fabrication marketplace separates the mask writer equipment customer (the mask supplier) from the final customer (wafer manufacturer) that will be most effected by the increase in mask cost that will result if a high speed mask writer is not available. Since no individual company will likely risk entering this market, some type of industry-wide funding model will be needed.

  2. Mask industry assessment: 2005

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Hector, Scott

    2005-11-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the fourth in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey contains all of the 2004 survey questions to provide an ongoing database. Additional questions were added to the survey covering operating cost factors and equipment utilization. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services, operating cost factors and equipment utilization. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from eight major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market. This participation rate is reduced by one captive from 2004. Note: Toppan, DuPont Photomasks Inc and AMTC (new) were consolidated into one input therefore the 2004 and 2005 surveys are basically equivalent.

  3. Sensorimotor supremacy: Investigating conscious and unconscious vision by masked priming

    PubMed Central

    Ansorge, Ulrich; Neumann, Odmar; Becker, Stefanie I.; Kälberer, Holger; Cruse, Holk

    2008-01-01

    According to the sensorimotor supremacy hypothesis, conscious perception draws on motor action. In the present report, we will sketch two lines of potential development in the field of masking research based on the sensorimotor supremacy hypothesis. In the first part of the report, evidence is reviewed that masked, invisible stimuli can affect motor responses, attention shifts, and semantic processes. After the review of the corresponding evidence – so-called masked priming effects – an approach based on the sensorimotor supremacy hypothesis is detailed as to how the question of a unitary mechanism of unconscious vision can be pursued by masked priming studies. In the second part of the report, different models and theories of backward masking and masked priming are reviewed. Types of models based on the sensorimotor hypothesis are discussed that can take into account ways in which sensorimotor processes (reflected in masked priming effects) can affect conscious vision under backward masking conditions. PMID:20517513

  4. Mask industry assessment: 2006

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia

    2006-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the fifth in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 survey. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  5. Mask industry assessment: 2009

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2009-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by David Powell Consulting to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the eighth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 through 2008 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry. This in combination with the past surveys represents a comprehensive view of changes in the industry.

  6. Mask industry assessment: 2008

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2008-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by David Powell Consulting to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the seventh in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 through 2007 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  7. Mask Industry Assessment: 2007

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia; Hughes, Greg

    2007-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the sixth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 and 2006 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  8. Mask industry assessment: 2002

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2002-12-01

    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. This assessment can be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of our critical mask industry. It should serve as a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  9. Mask and pattern characteristics

    NASA Technical Reports Server (NTRS)

    Routh, D. E.

    1972-01-01

    The use of the mask and pattern facility to include information on equipment accuracy, limitations, and pattern making capabilities is discussed. An insight is provided into potential areas of pattern applications, the sequence of mask making, as well as possible inputs and outputs available to the user.

  10. Mini Metal Masks.

    ERIC Educational Resources Information Center

    Henn, Cynthia

    2003-01-01

    Describes an art project used with kindergarten and first-grade students that focused on traditional African masks as part of a unit on the culture of West Africa. Discusses how the students created their clay masks. Includes lists of learning objectives and art materials. (CMK)

  11. Enhancement in Informational Masking

    ERIC Educational Resources Information Center

    Cao, Xiang; Richards, Virginia M.

    2012-01-01

    Purpose: The ability to detect a tone added to a random masker improves when a preview of the masker is provided. In 2 experiments, the authors explored the role that perceptual organization plays in this release from masking. Method: Detection thresholds were measured in informational masking studies. The maskers were drawn at random prior to…

  12. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  13. A mask manufacturer's perspective on maskless lithography

    NASA Astrophysics Data System (ADS)

    Buck, Peter; Biechler, Charles; Kalk, Franklin

    2005-11-01

    successful ML2 system solves the mask cost issue and thereby reduces the need and attractiveness of ML2. Are these concerns valid? In this paper we will present a perspective on maskless lithography from the considerable "direct write" experience of a mask manufacturer. We will examine the various business models proposed for ML2 insertion as well as the key technical challenges to achieving simultaneously the throughput and the lithographic quality necessary to become economically viable. We will consider the question of the economic viability of the mask industry in a post-ML2 world and will propose possible models where the mask industry can meaningfully participate.

  14. Lithographic performance evaluation of a contaminated EUV mask after cleaning

    SciTech Connect

    George, Simi; Naulleau, Patrick; Okoroanyanwu, Uzodinma; Dittmar, Kornelia; Holfeld, Christian; Wuest, Andrea

    2009-11-16

    The effect of surface contamination and subsequent mask surface cleaning on the lithographic performance of a EUV mask is investigated. SEMATECH's Berkeley micro-field exposure tool (MET) printed 40 nm and 50 nm line and space (L/S) patterns are evaluated to compare the performance of a contaminated and cleaned mask to an uncontaminated mask. Since the two EUV masks have distinct absorber architectures, optical imaging models and aerial image calculations were completed to determine any expected differences in performance. Measured and calculated Bossung curves, process windows, and exposure latitudes for the two sets of L/S patterns are compared to determine how the contamination and cleaning impacts the lithographic performance of EUV masks. The observed differences in mask performance are shown to be insignificant, indicating that the cleaning process did not appreciably affect mask performance.

  15. Vendor Capability for Low Thermal Expansion Mask Substrates for EUV Lithography

    SciTech Connect

    Blaedel, K L; Taylor, J S; Hector, S D; Yan, P Y; Ramamoorthy, A; Brooker, P D

    2002-04-12

    Development of manufacturing infrastructure is required to ensure a commercial source of mask substrates for the timely introduction of EUVL. Improvements to the low thermal expansion materials that compose the substrate have been made, but need to be scaled to production quantities. We have been evaluating three challenging substrate characteristics to determine the state of the infrastructure for the finishing of substrates. First, surface roughness is on track and little risk is associated with achieving the roughness requirement as an independent specification. Second, with new flatness-measuring equipment just coming on line, the vendors are poised for improvement toward the SEMI P37 flatness specification. Third, significant acceleration is needed in the reduction of defect levels on substrates. The lack of high-sensitivity defect metrology at the vendors' sites is limiting progress in developing substrates for EWL.

  16. 2012 Mask Industry Survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt; Litt, Lloyd C.

    2012-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to semiconductor industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. 2012 marks the 11th consecutive year for the mask industry survey. This year's survey and reporting structure are similar to those of the previous years with minor modifications based on feedback from past years and the need to collect additional data on key topics. Categories include general mask information, mask processing, data and write time, yield and yield loss, delivery times, and maintenance and returns. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. Results, initial observations, and key comparisons between the 2011 and 2012 survey responses are shown here, including multiple indications of a shift towards the manufacturing of higher end photomasks.

  17. Masking by Gratings Predicted by an Image Sequence Discriminating Model: Testing Models for Perceptual Discrimination Using Repeatable Noise

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.; Null, Cynthia H. (Technical Monitor)

    1998-01-01

    Adding noise to stimuli to be discriminated allows estimation of observer classification functions based on the correlation between observer responses and relevant features of the noisy stimuli. Examples will be presented of stimulus features that are found in auditory tone detection and visual vernier acuity. using the standard signal detection model (Thurstone scaling), we derive formulas to estimate the proportion of the observers decision variable variance that is controlled by the added noise. one is based on the probability of agreement of the observer with him/herself on trials with the same noise sample. Another is based on the relative performance of the observer and the model. When these do not agree, the model can be rejected. A second derivation gives the probability of agreement of observer and model when the observer follows the model except for internal noise. Agreement significantly less than this amount allows rejection of the model.

  18. Antibody-mediated immune suppression of erythrocyte alloimmunization can occur independently from red cell clearance or epitope masking in a murine model.

    PubMed

    Yu, Honghui; Stowell, Sean R; Bernardo, Lidice; Hendrickson, Jeanne E; Zimring, James C; Amash, Alaa; Uchikawa, Makoto; Lazarus, Alan H

    2014-09-15

    Anti-D can prevent immunization to the RhD Ag on RBCs, a phenomenon commonly termed Ab-mediated immune suppression (AMIS). The most accepted theory to explain this effect has been the rapid clearance of RBCs. In mouse models using SRBC, these xenogeneic cells are always rapidly cleared even without Ab, and involvement of epitope masking of the SRBC Ags by the AMIS-inducing Ab (anti-SRBC) has been suggested. To address these hypotheses, we immunized mice with murine transgenic RBCs expressing the HOD Ag (hen egg lysozyme [HEL], in sequence with ovalbumin, and the human Duffy transmembrane protein) in the presence of polyclonal Abs or mAbs to the HOD molecule. The isotype, specificity, and ability to induce AMIS of these Abs were compared with accelerated clearance as well as steric hindrance of the HOD Ag. Mice made IgM and IgG reactive with the HEL portion of the molecule only. All six of the mAbs could inhibit the response. The HEL-specific Abs (4B7, IgG1; GD7, IgG2b; 2F4, IgG1) did not accelerate clearance of the HOD-RBCs and displayed partial epitope masking. The Duffy-specific Abs (MIMA 29, IgG2a; CBC-512, IgG1; K6, IgG1) all caused rapid clearance of HOD RBCs without steric hindrance. To our knowledge, this is the first demonstration of AMIS to erythrocytes in an all-murine model and shows that AMIS can occur in the absence of RBC clearance or epitope masking. The AMIS effect was also independent of IgG isotype and epitope specificity of the AMIS-inducing Ab. PMID:25122924

  19. Temporal processes in prime–mask interaction: Assessing perceptual consequences of masked information

    PubMed Central

    Scharlau, Ingrid

    2008-01-01

    Visual backward masking is frequently used to study the temporal dynamics of visual perception. These dynamics may include the temporal features of conscious percepts, as suggested, for instance, by the asynchronous–updating model (Neumann, 1982) and perceptual–retouch theory ((Bachmann, 1994). These models predict that the perceptual latency of a visual backward mask is shorter than that of a like reference stimulus that was not preceded by a masked stimulus. The prediction has been confirmed by studies using temporal–order judgments: For certain asynchronies between mask and reference stimulus, temporal–order reversals are quite frequent (e.g. Scharlau, & Neumann, 2003a). However, it may be argued that these reversals were due to a response bias in favour of the mask rather than true temporal-perceptual effects. I introduce two measures for assessing latency effects that (1) are not prone to such a response bias, (2) allow to quantify the latency gain, and (3) extend the perceptual evidence from order reversals to duration/interval perception, that is, demonstrate that the perceived interval between a mask and a reference stimulus may be shortened as well as prolonged by the presence of a masked stimulus. Consequences for theories of visual masking such as asynchronous–updating, perceptual–retouch, and reentrant models are discussed. PMID:20517512

  20. Protective Face Mask

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mask to protect the physically impaired from injuries to the face and head has been developed by Langley Research Center. It is made of composite materials, usually graphite or boron fibers woven into a matrix. Weighs less than three ounces.

  1. Masked Photocathode for Photoinjector

    SciTech Connect

    Qiang, Ji

    2010-01-21

    In this research note, we propose a scheme to insert a photocathode inside a photoinjector for generating high brightness electron beam. Instead of mounting the photocathode onto the electrode, a masked electrode with small hole is used to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material very simple by rotating the photocathode behind the mask into the hole. This will significantly increase the usage lifetime of a photocathode. Furthermore, this also helps reduce the dark current or secondary electron emission from the photocathode. The hole on the mask also provides a transverse cut-off to the Gaussian laser profile which can be beneficial from the beam dynamics point of view.

  2. Neonatal resuscitation 2: an evaluation of manual ventilation devices and face masks

    PubMed Central

    O'Donnell, C; Davis, P; Lau, R; Dargaville, P; Doyle, L; Morley, C

    2005-01-01

    Background: The key to successful neonatal resuscitation is effective ventilation. Little evidence exists to guide clinicians in their choice of manual ventilation device or face mask. The expiratory tidal volume measured at the mask (VTE(mask)) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. Aim: To compare the efficacy of (a) the Laerdal infant resuscitator and the Neopuff infant resuscitator, used with (b) round and anatomically shaped masks in a model of neonatal resuscitation. Methods: Thirty four participants gave positive pressure ventilation to a mannequin at specified pressures with each of the four device-mask combinations. Flow, inspiratory tidal volume at the face mask (VTI(mask)), VTE(mask), and airway pressure were recorded. Leakage from the mask was calculated from VTI(mask) and VTE(mask). Results: A total of 10 780 inflations were recorded and analysed. Peak inspiratory pressure targets were achieved equally with the Laerdal and Neopuff resuscitators. Positive end expiratory pressure was delivered with the Neopuff but not the Laerdal device. Despite similar peak pressures, VTE(mask) varied widely. Mask leakage was large for each combination of device and mask. There were no differences between the masks. Conclusion: During face mask ventilation of a neonatal resuscitation mannequin, there are large leaks around the face mask. Airway pressure is a poor proxy for volume delivered during positive pressure ventilation through a mask. PMID:15871989

  3. Mask Industry Assessment: 2010

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Chan, David Y.

    2010-09-01

    A survey created supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the ninth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. It will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was basically the same as the 2005 through 2009 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  4. Mask Industry Assessment: 2011

    NASA Astrophysics Data System (ADS)

    Chan, Y. David

    2011-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the tenth in the current series of annual reports. With ongoing industry support, the report has been used as one of the baselines to gain perspective on the technical and business status of the mask and microelectronics industries. It continues to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was essentially the same as the 2005 through 2010 surveys. Questions are grouped into following categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  5. New mask technology challenges

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2001-09-01

    Mask technology development has accelerated dramatically in recent years from the glacial pace of the last three decades to the rapid and sometimes simultaneous introductions of new wavelengths and mask-based resolution enhancement techniques. The nature of the semiconductor business has also become one driven by time-to-market as an overwhelming factor in capturing market share and profit. These are among the factors that have created enormous stress on the mask industry to produce masks with enhanced capabilities, such as phase-shifting attenuators, sub-resolution assist bars, and optical proximity correction (OPC) features, while maintaining or reducing cost and cycle time. The mask can no longer be considered a commodity item that is purchased form the lowest-cost supplier. Instead, it must now be promoted as an integral part of the technical and business case for a total lithographic solution. Improving partnership between designer, mask-maker, and wafer lithographer will be the harbinger of success in finding a profitable balance of capability, cost, and cycle time. Likewise for equipment infrastructure development, stronger partnership on the international level is necessary to control development cost and mitigate schedule and technical risks.

  6. Masks: The Artist in Me

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2009-01-01

    Whether masks are made from cardboard, papier-mache, metal, wood, leather, fabric, clay or any combination of these materials, they bring out the artist in people. Young children like to wear masks when they play to pretend they were another person or animal. Masks let them fantasize and be creative. The author's students made masks representing…

  7. Rates and mechanisms of optic contamination in the EUVL engineering test stand

    NASA Astrophysics Data System (ADS)

    Grunow, Philip A.; Klebanoff, Leonard E.; Graham, Samuel, Jr.; Haney, Steven J.; Clift, W. Miles

    2003-06-01

    The EUV Engineering Test Stand (ETS) is a full-field, alpha-class Extreme Ultraviolet Lithography (EUVL) tool that has demonstrated the printing of 70 nm resolution scanned images. The tool employs Mo/Si multilayer optics that reflect EUV radiation (13.4nm / 92.5eV) with ~67% peak reflectance per optic. For good reflectivity, many (≥40)Mo/Si layers must be present. Consequently, processes such as plasma-induced multilayer erosion, which reduces the number of bilayer pairs on plasma-facing optics, need to be understood. Since most materials readily absorb EUV photons, it is important to prevent contamination of mirror surfaces with EUV absorbing material. Contamination can occur by EUV photons "cracking" hydrocarbons or other species absorbed on the optical surfaces. The first ETS condenser component, referred to as C1, is coated with Mo/Si multilayers. Data collected from Mo/Si witness plates placed at the C1 position indicate erosion, using the Xe Laser Produced Plasma (LPP) spray jet, of 1 bilayer per ~15 million shots. Preliminary experiments with a filament jet yielded a significantly higher erosion rate. In the spray jet studies, erosion was found to depend sensitively on the composition of the residual background environment. Addition of low levels, ~7x10-7 Torr, of H2O to the vacuum background produced oxidation of the Si cap, and significantly slowed spray jet-induced erosion. Operation of the plasma changed the environment in the Illuminator Chamber from oxidizing to carbonizing, thereby changing the nature of the contamination found environment at the C3 optic which does not view the plasma directly (and therefore does not erode). The change in environment is attributed to plasma-induced outgassing of fluorocarbons in the Illuminator. Due to the non-zero conductance between the Illuminator and Main Chambers, fluorocarbons were also found in the Main Chamber during Xe LPP operation. RGA data are presented that document the effect. In the presence of such

  8. Comparison of different approaches for the correction of residual mask proximity effects

    NASA Astrophysics Data System (ADS)

    Mittermeier, E.; Franke, T.

    2005-11-01

    Linearity- and proximity effects do exist on actual masks even if manufactured with current state-of-the-art processes. The impact of these short-range mask effects on the results of the optical lithography for features sizes relevant in the 90nm-node is investigated. For this purpose, an approach is chosen which employs mask process simulations in combination with simulations of optical lithography. Two mask models are deduced and verified from measurement data of an existing mask process. The lithographic results are simulated using parameters of current optical- and process models. Both mask models are used to evaluate the impact of the mask proximity effects on the printing results of optical lithography for critical pattern geometries. The differences in the mask proximity characteristics lead to additional pattern-dependent CD-offtargets after wafer lithography. Additionally, a mask-process dependent sensitivity of the CD-offtarget on the presence of optical sub-resolution assist features is observed. Based on these simulation results, the efficiencies of two techniques for the correction of the mask proximity signatures are evaluated. The application of mask sub-resolution features is compared with model-based data correction on mask level. Mask sub-resolution assist features reduce the influence of the mask process significantly and provide an enhanced stability against mask process fluctuations. Data correction yields even better correction results at the cost of an increased complexity due to the susceptibility to changes of the mask processes characteristics.

  9. Mask cost of ownership for advanced lithography

    NASA Astrophysics Data System (ADS)

    Muzio, Edward G.; Seidel, Philip K.

    2000-07-01

    As technology advances, becoming more difficult and more expensive, the cost of ownership (CoO) metric becomes increasingly important in evaluating technical strategies. The International SEMATECH CoC analysis has steadily gained visibility over the past year, as it attempts to level the playing field between technology choices, and create a fair relative comparison. In order to predict mask cots for advanced lithography, mask process flows are modeled using bets-known processing strategies, equipment cost, and yields. Using a newly revised yield mode, and updated mask manufacture flows, representative mask flows can be built. These flows are then used to calculate mask costs for advanced lithography down to the 50 nm node. It is never the goal of this type of work to provide absolute cost estimates for business planning purposes. However, the combination of a quantifiable yield model with a clearly defined set of mask processing flows and a cost model based upon them serves as an excellent starting point for cost driver analysis and process flow discussion.

  10. Overview of Mask Metrology

    NASA Astrophysics Data System (ADS)

    Rice, Bryan J.; Jindal, Vibhu; Lin, C. C.; Harris-Jones, Jenah; Kwon, Hyuk Joo; Ma, Hsing-Chien; Goldstein, Michael; Chan, Yau-Wai; Goodwin, Frank

    2011-11-01

    Extreme ultraviolet (EUV) lithography is the successor to optical lithography and will enable advanced patterning in semiconductor manufacturing processes down to the 8 nm half pitch technology node and beyond. However, before EUV can successfully be inserted into high volume manufacturing a few challenges must be overcome. Central among these remaining challenges is the requirement to produce "defect free" EUV masks. Mask blank defects have been one of the top challenges in the commercialization of extreme ultraviolet (EUV) lithography. To determine defect sources and devise mitigation solutions, detailed characterization of defects is critical. However, small defects pose challenges in metrology scale-up. SEMATECH has a comprehensive metrology strategy to address any defect larger than a 20 nm core size to obtain solutions for defect-free EUV mask blanks. SEMATECH's Mask Blank Development Center has been working since 2003 to develop the technology to support defect free EUV mask blanks. Since 2003, EUV mask blank defects have been reduced from 10000 of size greater than 100 nm to about a few tens at size 70 nm. Unfortunately, today's state of the art defect levels are still about 10 to 100 times higher than needed. Closing this gap requires progress in the various processes associated with glass substrate creation and multilayer deposition. That process development improvement in turn relies upon the availability of metrology equipment that can resolve and chemically characterize defects as small as 30 nm. The current defect reduction efforts at SEMATECH have intensively included a focus on inspection and characterization. The facility boasts nearly 100M of metrology hardware, including an FEI Titan TEM, Lasertec M1350 and M7360 tools, an actinic inspection tool, AFM, SPM, and scanning auger capabilities. The newly established Auger tool at SEMATECH can run a standard 6-inch mask blank and is already providing important information on sub-100 nm defects on EUV

  11. Orion Emergency Mask Approach

    NASA Technical Reports Server (NTRS)

    Tuan, George C.; Graf, John C.

    2008-01-01

    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction temperature and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  12. Orion Emergency Mask Approach

    NASA Technical Reports Server (NTRS)

    Tuan, George C.; Graf, John C.

    2009-01-01

    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction time, breakthroughs, and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  13. Anticipating and controlling mask costs within EDA physical design

    NASA Astrophysics Data System (ADS)

    Rieger, Michael L.; Mayhew, Jeffrey P.; Melvin, Lawrence S.; Lugg, Robert M.; Beale, Daniel F.

    2003-08-01

    For low k1 lithography, more aggressive OPC is being applied to critical layers, and the number of mask layers with OPC treatments is growing rapidly. The 130 nm, process node required, on average, 8 layers containing rules- or model-based OPC. The 90 nm node will have 16 OPC layers, of which 14 layers contain aggressive model-based OPC. This escalation of mask pattern complexity, coupled with the predominant use of vector-scan e-beam (VSB) mask writers contributes to the rising costs of advanced mask sets. Writing times for OPC layouts are several times longer than for traditional layouts, making mask exposure the single largest cost component for OPC masks. Lower mask yields, another key factor in higher mask costs, is also aggravated by OPC. Historical mask set costs are plotted below. The initial cost of a 90 nm-node mask set will exceed one million dollars. The relative impact of mask cost on chip depends on how many total wafers are printed with each mask set. For many foundry chips, where unit production is often well below 1000 wafers, mask costs are larger than wafer processing costs. Further increases in NRE may begin to discourage these suppliers' adoption to 90 nm and smaller nodes. In this paper we will outline several alternatives for reducing mask costs by strategically leveraging dimensional margins. Dimensional specifications for a particular masking layer usually are applied uniformly to all features on that layer. As a practical matter, accuracy requirements on different features in the design may vary widely. Take a polysilicon layer, for example: global tolerance specifications for that layer are driven by the transistor-gate requirements; but these parameters over-specify interconnect feature requirements. By identifying features where dimensional accuracy requirements can be reduced, additional margin can be leveraged to reduce OPC complexity. Mask writing time on VSB tools will drop in nearly direct proportion to reduce shot count. By

  14. Visually lossless coding based on temporal masking in human vision

    NASA Astrophysics Data System (ADS)

    Adzic, Velibor; Hock, Howard S.; Kalva, Hari

    2014-02-01

    This paper presents a method for perceptual video compression that exploits the phenomenon of backward temporal masking. We present an overview of visual temporal masking and discuss models to identify portions of a video sequences masked due to this phenomenon exhibited by the human visual system. A quantization control model based on the psychophysical model of backward visual temporal masking was developed. We conducted two types of subjective evaluations and demonstrated that the proposed method up to 10% bitrate savings on top of state of the art encoder with visually identical video. The proposed methods were evaluated using HEVC encoder.

  15. Apodized Phase Mask Coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlotti, Alexis

    2013-01-01

    Among the optical instruments proposed to detect and characterize exoplanets, phase masks coronagraphs offer very small inner working angles. Designed for off-axis telescopes, their performance is greatly reduced when used with centrally obstructed apertures such as those of the Palomar telescope, the very large telescope, or the James Webb space telescope. However, a clear circular aperture is not the only pupil shape for which a phase mask coronagraph can work properly. In fact, for a given centrally obstructed aperture, we show that it is possible to compute optimal apodizers that help achieve stellar extinction levels similar to those obtained in the ideal case of an off-axis telescope. Trade-offs exist between these levels, the transmission of the apodizer, and the area covered by the Lyot stop. We detail the Fourier optics formalism that makes these optimizations possible, as well as a few examples of shaped pupils. Some are designed for a four-quadrants phase mask, and some others for a vortex phase mask. We also offer a comparison with a coronagraph solely composed of a shaped pupil.

  16. Masked mycotoxins: A review

    PubMed Central

    Berthiller, Franz; Crews, Colin; Dall'Asta, Chiara; Saeger, Sarah De; Haesaert, Geert; Karlovsky, Petr; Oswald, Isabelle P; Seefelder, Walburga; Speijers, Gerrit; Stroka, Joerg

    2013-01-01

    The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders. PMID:23047235

  17. Competing for Consciousness: Prolonged Mask Exposure Reduces Object Substitution Masking

    ERIC Educational Resources Information Center

    Goodhew, Stephanie C.; Visser, Troy A. W.; Lipp, Ottmar V.; Dux, Paul E.

    2011-01-01

    In object substitution masking (OSM) a sparse, temporally trailing 4-dot mask impairs target identification, even though it has different contours from, and does not spatially overlap with the target. Here, we demonstrate a previously unknown characteristic of OSM: Observers show reduced masking at prolonged (e.g., 640 ms) relative to intermediate…

  18. Masking with faces in central visual field under a variety of temporal schedules.

    PubMed

    Daar, Marwan; Wilson, Hugh R

    2015-11-01

    With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100 ms. PMID:26381296

  19. Compensation of overlay errors due to mask bending and non-flatness for EUV masks

    NASA Astrophysics Data System (ADS)

    Chandhok, Manish; Goyal, Sanjay; Carson, Steven; Park, Seh-Jin; Zhang, Guojing; Myers, Alan M.; Leeson, Michael L.; Kamna, Marilyn; Martinez, Fabian C.; Stivers, Alan R.; Lorusso, Gian F.; Hermans, Jan; Hendrickx, Eric; Govindjee, Sanjay; Brandstetter, Gerd; Laursen, Tod

    2009-03-01

    EUV blank non-flatness results in both out of plane distortion (OPD) and in-plane distortion (IPD) [3-5]. Even for extremely flat masks (~50 nm peak to valley (PV)), the overlay error is estimated to be greater than the allocation in the overlay budget. In addition, due to multilayer and other thin film induced stresses, EUV masks have severe bow (~1 um PV). Since there is no electrostatic chuck to flatten the mask during the e-beam write step, EUV masks are written in a bent state that can result in ~15 nm of overlay error. In this article we present the use of physically-based models of mask bending and non-flatness induced overlay errors, to compensate for pattern placement of EUV masks during the e-beam write step in a process we refer to as E-beam Writer based Overlay error Correction (EWOC). This work could result in less restrictive tolerances for the mask blank non-flatness specs which in turn would result in less blank defects.

  20. Mask defect printing mechanisms for future lithography generations

    NASA Astrophysics Data System (ADS)

    Erdmann, Andreas; Graf, Thomas; Bubke, Karsten; Höllein, Ingo; Teuber, Silvio

    2006-03-01

    Mask defects are of increasing concern for future lithography generations. The improved resolution capabilities of immersion and EUV systems increase also the sensitivity of these systems with respect to small imperfections of the mask. Advanced mask technologies such as alternating phase shift masks (AltPSM), chromeless phase shift lithography (CPL), or "thick" absorbers on EUV masks introduce new defect types. The paper presents an application of rigorous electromagnetic field modeling for the study of typical defect printing mechanisms in ArF immersion lithography and in EUV lithography. For standard imaging and mask technologies, such as binary masks or attenuated phase shift masks, small defects usually print as linewidth or critical dimension (CD) errors with the largest effect at best focus. For AltPSM, CPL masks, and EUV masks this is not always the case. Several unusual printing scenarios were observed: placement errors due to defects can become more critical than CD-errors, defects may print more critical at defocus positions different from the center of the process window, the defect printing may become asymmetric through focus, and the risk of defect printing depends on the polarization of the used light source. Several simulation examples will demonstrate these effects. Rigorous EMF simulations in combination with vector imaging simulations are very useful to understand the origins of the observed defect printing mechanisms.

  1. Mask Blank Defect Detection

    SciTech Connect

    Johnson, M A; Sommargren, G E

    2000-02-04

    Mask blanks are the substrates that hold the master patterns for integrated circuits. Integrated circuits are semiconductor devices, such as microprocessors (mPs), dynamic random access memory (DRAMs), and application specific integrated circuits (ASICs) that are central to the computer, communication, and electronics industries. These devices are fabricated using a set of master patterns that are sequentially imaged onto light-sensitive coated silicon wafers and processed to form thin layers of insulating and conductive materials on top of the wafer. These materials form electrical paths and transistors that control the flow of electricity through the device. For the past forty years the semiconductor industry has made phenomenal improvements in device functionality, compactness, speed, power, and cost. This progress is principally due to the exponential decrease in the minimum feature size of integrated circuits, which has been reduced by a factor of {radical}2 every three years. Since 1992 the Semiconductor Industry Association (SIA) has coordinated the efforts of producing a technology roadmap for semiconductors. In the latest document, ''The International Technology Roadmap for Semiconductors: 1999'', future technology nodes (minimum feature sizes) and targeted dates were specified and are summarized in Table 1. Lithography is the imaging technology for producing a de-magnified image of the mask on the wafer. A typical de-magnification factor is 4. Mask blank defects as small as one-eighth the equivalent minimum feature size are printable and may cause device failure. Defects might be the result of the surface preparation, such as polishing, or contamination due to handling or the environment. Table 2 shows the maximum tolerable defect sizes on the mask blank for each technology node. This downward trend puts a tremendous burden on mask fabrication, particularly in the area of defect detection and reduction. A new infrastructure for mask inspection will be

  2. Respiratory Source Control Using Surgical Masks With Nanofiber Media

    PubMed Central

    Skaria, Shaji D.; Smaldone, Gerald C.

    2014-01-01

    Background: Potentially infected individuals (‘source’) are sometimes encouraged to use face masks to reduce exposure of their infectious aerosols to others (‘receiver’). To improve compliance with Respiratory Source Control via face mask and therefore reduce receiver exposure, a mask should be comfortable and effective. We tested a novel face mask designed to improve breathability and filtration using nanofiber filtration. Methods: Using radiolabeled test aerosols and a calibrated exposure chamber simulating source to receiver interaction, facepiece function was measured with a life-like ventilated manikin model. Measurements included mask airflow resistance (pressure difference during breathing), filtration, (mask capture of exhaled radiolabeled test aerosols), and exposure (the transfer of ‘infectious’ aerosols from the ‘source’ to a ‘receiver’). Polydisperse aerosols were measured at the source with a mass median aerodynamic diameter of 0.95 µm. Approximately 90% of the particles were <2.0 µm. Tested facepieces included nanofiber prototype surgical masks, conventional surgical masks, and for comparison, an N95-class filtering facepiece respirator (commonly known as an ‘N95 respirator’). Airflow through and around conventional surgical face mask and nanofiber prototype face mask was visualized using Schlieren optical imaging. Results: Airflow resistance [ΔP, cmH2O] across sealed surgical masks (means: 0.1865 and 0.1791 cmH2O) approached that of the N95 (mean: 0.2664 cmH2O). The airflow resistance across the nanofiber face mask whether sealed or not sealed (0.0504 and 0.0311 cmH2O) was significantly reduced in comparison. In addition, ‘infected’ source airflow filtration and receiver exposure levels for nanofiber face masks placed on the source were comparable to that achieved with N95 placed on the source; 98.98% versus 82.68% and 0.0194 versus 0.0557, respectively. Compared to deflection within and around the conventional face

  3. Mask characterization for critical dimension uniformity budget breakdown in advanced extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Nikolsky, Peter; Strolenberg, Chris; Nielsen, Rasmus; Nooitgedacht, Tjitte; Davydova, Natalia; Yang, Greg; Lee, Shawn; Park, Chang-Min; Kim, Insung; Yeo, Jeong-Ho

    2013-04-01

    As the International Technology Roadmap for Semiconductors critical dimension uniformity (CDU) specification shrinks, semiconductor companies need to maintain a high yield of good wafers per day and high performance (and hence market value) of finished products. This cannot be achieved without continuous analysis and improvement of on-product CDU as one of the main drivers for process control and optimization with better understanding of main contributors from the litho cluster: mask, process, metrology and scanner. We will demonstrate a study of mask CDU characterization and its impact on CDU Budget Breakdown (CDU BB) performed for advanced extreme ultraviolet (EUV) lithography with 1D (dense lines) and 2D (dense contacts) feature cases. We will show that this CDU contributor is one of the main differentiators between well-known ArFi and new EUV CDU budgeting principles. We found that reticle contribution to intrafield CDU should be characterized in a specific way: mask absorber thickness fingerprints play a role comparable with reticle CDU in the total reticle part of the CDU budget. Wafer CD fingerprints, introduced by this contributor, may or may not compensate variations of mask CDs and hence influence on total mask impact on intrafield CDU at the wafer level. This will be shown on 1D and 2D feature examples. Mask stack reflectivity variations should also be taken into account: these fingerprints have visible impact on intrafield CDs at the wafer level and should be considered as another contributor to the reticle part of EUV CDU budget. We also observed mask error enhancement factor (MEEF) through field fingerprints in the studied EUV cases. Variations of MEEF may play a role towards the total intrafield CDU and may need to be taken into account for EUV lithography. We characterized MEEF-through-field for the reviewed features, with results herein, but further analysis of this phenomenon is required. This comprehensive approach to quantifying the mask part of

  4. Masked multichannel analyzer

    DOEpatents

    Winiecki, A.L.; Kroop, D.C.; McGee, M.K.; Lenkszus, F.R.

    1984-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  5. Masked multichannel analyzer

    DOEpatents

    Winiecki, Alan L.; Kroop, David C.; McGee, Marilyn K.; Lenkszus, Frank R.

    1986-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  6. [Intubating laryngeal mask].

    PubMed

    Langenstein, H; Möller, F

    1998-01-01

    To improve the success of blind intubation through a laryngeal mask, Dr. A.I.J. Brain constructed the intubating laryngeal mask airway (ILMA), marketed under the name Fastrach. The new construction allows blind intubation with highly flexible endotracheal tubes up to 8 mm ID with cuff (straight Woodbridge type), securing the airway around the intubation process and maintaining most of the characteristics of a standard laryngeal mask airway (SLMA), including contraindications. An additional contraindication is the existence of a Zenker diverticle. Up to now, eight working groups reported a success rate of blind intubation through the ILMA of more than 90% in about 1,200 patients, with a success rate of blind intubation of more than 50% for the first intubation attempt. Ten percent of the patients were difficult to intubate with the same success rate for blind intubation as in normal patients. Reduced mouth opening does not seem to hinder the use of the ILMA in spite of its increased outer diameter of 2 cm, as long as it is possible to enlarge the mouth opening to > 2 cm during anaesthesia. The new ILMA more than doubles the success of blind intubation compared to an SLMA, irrespective of a large variety of intubation difficulties. Correct judgement of endotracheal tube position is mandatory. The ILMA has the potential to be used in patients who are difficult to intubate and to substitute the SLMA in "cannot ventilate--cannot intubate" situations. The future will show if the ILMA also will improve emergency airway management by inexperienced personnel, including intubation, as has been shown for the standard laryngeal mask airway in cardiopulmonary resuscitation for ventilation only. PMID:9611362

  7. Mask strategy at International SEMATECH

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2002-08-01

    International SEMATECH (ISMT) is a consortium consisting of 13 leading semiconductor manufacturers from around the globe. Its objective is to develop the infrastructure necessary for its member companies to realize the International Technology Roadmap for Semiconductors (ITRS) through efficiencies of shared development resources and knowledge. The largest area of effort is lithography, recognized as a crucial enabler for microelectronics technology progress. Within the Lithography Division, most of the efforts center on mask-related issues. The development strategy at International SEMATCH will be presented and the interlock of lithography projects clarified. Because of the limited size of the mask production equipment market, the business case is weak for aggressive investment commensurate with the pace of the International Technology Roadmap for Semiconductors. With masks becoming the overwhelming component of lithography cost, new ways of reducing or eliminating mask costs are being explored. Will mask technology survive without a strong business case? Will the mask industry limit the growth of the semiconductor industry? Are advanced masks worth their escalating cost? An analysis of mask cost from the perspective of mask value imparted to the user is presented with examples and generic formulas for the reader to apply independently. A key part to the success for both International SEMATECH and the industry globally will be partnerships on both the local level between mask-maker and mask-user, and the macro level where global collaborations will be necessary to resolve technology development cost challenges.

  8. Incorporating mask topography edge diffraction in photolithography simulations.

    PubMed

    Tirapu-Azpiroz, Jaione; Yablonovitch, Eli

    2006-04-01

    In deep ultraviolet lithography simulations, conventional application of Kirchhoff's boundary conditions on the mask surface provides the so-called "thin-mask" approximation of the object field. Current subwavelength lithographic operation, however, places a serious limitation on this approximation, which fails to account for the topographical, or "thick-mask," effects. In this paper, a new simulation model is proposed that is theoretically founded on the well-established physical theory of diffraction. This model relies on the key result that diffraction effects can be interpreted as an intrinsic edge property, and modeled with just two fixed parameters: width and transmission coefficient of a locally determined boundary layer applied to each chrome edge. The proposed model accurately accounts for thick-mask effects of the fields on the mask, greatly improving the accuracy of aerial image simulations in photolithography, while maintaining a reasonable computational cost. PMID:16604762

  9. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Hector, Scott; Marmillion, Pat; Lercel, Michael

    2006-06-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. In 2002, a survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of mask equipment. The 2005 survey was the fourth in the current series of annual surveys. The survey data can be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. The results may be used to guide future investments on critical path issues. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services, operating cost factors, and equipment utilization. Because the questions covering operating cost factors and equipment utilization were just added to the survey, no trend analysis is possible. Within each category are many questions that together create a detailed profile of both the business and technical status of the mask industry. The assessment participation has changed from year to year. The 2005 survey, for example, includes inputs from eight major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market.

  10. Mask Design for the Space Interferometry Mission Internal Metrology

    NASA Technical Reports Server (NTRS)

    Marx, David; Zhao, Feng; Korechoff, Robert

    2005-01-01

    This slide presentation reviews the mask design used for the internal metrology of the Space Interferometry Mission (SIM). Included is information about the project, the method of measurements with SIM, the internal metrology, numerical model of internal metrology, wavefront examples, performance metrics, and mask design

  11. Metabolic power of European starlings Sturnus vulgaris during flight in a wind tunnel, estimated from heat transfer modelling, doubly labelled water and mask respirometry.

    PubMed

    Ward, S; Möller, U; Rayner, J M V; Jackson, D M; Nachtigall, W; Speakman, J R

    2004-11-01

    It is technically demanding to measure the energetic cost of animal flight. Each of the previously available techniques has some disadvantage as well advantages. We compared measurements of the energetic cost of flight in a wind tunnel by four European starlings Sturnus vulgaris made using three independent techniques: heat transfer modelling, doubly labelled water (DLW) and mask respirometry. We based our heat transfer model on thermal images of the surface temperature of the birds and air flow past the body and wings calculated from wing beat kinematics. Metabolic power was not sensitive to uncertainty in the value of efficiency when estimated from heat transfer modelling. A change in the assumed value of whole animal efficiency from 0.19 to 0.07 (the range of estimates in previous studies) only altered metabolic power predicted from heat transfer modelling by 13%. The same change in the assumed value of efficiency would cause a 2.7-fold change in metabolic power if it were predicted from mechanical power. Metabolic power did not differ significantly between measurements made using the three techniques when we assumed an efficiency in the range 0.11-0.19, although the DLW results appeared to form a U-shaped power-speed curve while the heat transfer model and respirometry results increased linearly with speed. This is the first time that techniques for determining metabolic power have been compared using data from the same birds flying under the same conditions. Our data provide reassurance that all the techniques produce similar results and suggest that heat transfer modelling may be a useful method for estimating metabolic rate. PMID:15531650

  12. High-etching selectivity of spin-on-carbon hard mask process for 22nm node and beyond

    NASA Astrophysics Data System (ADS)

    Iwao, Fumiko; Shimura, Satoru; Kyouda, Hideharu; Oyama, Kenichi; Yamauchi, Shohei; Hara, Arisa; Natori, Sakurako; Yaegashi, Hidetami

    2012-03-01

    As part of the trend toward finer semiconductor design rules, the resist film thickness is getting thinner, and the etching technology that uses resist masking is getting more difficult. To solve such a problem in recent years, the film structure used in the resist process also is changing from the single-layer process (BARC and resist stacked film) to the multi-layer process (Carbon hard-mask, middle layer and resist stacked film) The carbon hard-mask of multi-layer process can be divided into two kinds, which are the CVD-carbon (CVD-C) that uses the chemical vapor deposition method and Spin-on-carbon (SOC) that uses the spin-coating method. CVD-C is very attractive for ensuring the high etching selection ratio, but still has major challenges in particle reduction, lower planarization of substrate and high process cost. On the other hand, SOC is very attractive for low cost process, high level of planarization of substrate and no particles. Against this background, we verify the development of the SOC that had the high etch selection ratio by improving etching condition, material and SOC cure condition. Moreover, we can fabricate below 30nm SiO2 patterning and the possibility of development with extreme ultraviolet lithography (EUVL) was suggested. This paper reports on the results of a comprehensive process evaluation of a SOC based multi-layer technology using lithography clusters, etching tools.

  13. Overlay improvement by exposure map based mask registration optimization

    NASA Astrophysics Data System (ADS)

    Shi, Irene; Guo, Eric; Chen, Ming; Lu, Max; Li, Gordon; Li, Rivan; Tian, Eric

    2015-03-01

    Along with the increased miniaturization of semiconductor electronic devices, the design rules of advanced semiconductor devices shrink dramatically. [1] One of the main challenges of lithography step is the layer-to-layer overlay control. Furthermore, DPT (Double Patterning Technology) has been adapted for the advanced technology node like 28nm and 14nm, corresponding overlay budget becomes even tighter. [2][3] After the in-die mask registration (pattern placement) measurement is introduced, with the model analysis of a KLA SOV (sources of variation) tool, it's observed that registration difference between masks is a significant error source of wafer layer-to-layer overlay at 28nm process. [4][5] Mask registration optimization would highly improve wafer overlay performance accordingly. It was reported that a laser based registration control (RegC) process could be applied after the pattern generation or after pellicle mounting and allowed fine tuning of the mask registration. [6] In this paper we propose a novel method of mask registration correction, which can be applied before mask writing based on mask exposure map, considering the factors of mask chip layout, writing sequence, and pattern density distribution. Our experiment data show if pattern density on the mask keeps at a low level, in-die mask registration residue error in 3sigma could be always under 5nm whatever blank type and related writer POSCOR (position correction) file was applied; it proves random error induced by material or equipment would occupy relatively fixed error budget as an error source of mask registration. On the real production, comparing the mask registration difference through critical production layers, it could be revealed that registration residue error of line space layers with higher pattern density is always much larger than the one of contact hole layers with lower pattern density. Additionally, the mask registration difference between layers with similar pattern density

  14. Mask fabrication process

    DOEpatents

    Cardinale, Gregory F.

    2000-01-01

    A method for fabricating masks and reticles useful for projection lithography systems. An absorber layer is conventionally patterned using a pattern and etch process. Following the step of patterning, the entire surface of the remaining top patterning photoresist layer as well as that portion of an underlying protective photoresist layer where absorber material has been etched away is exposed to UV radiation. The UV-exposed regions of the protective photoresist layer and the top patterning photoresist layer are then removed by solution development, thereby eliminating the need for an oxygen plasma etch and strip and chances for damaging the surface of the substrate or coatings.

  15. Masks of the Universe

    NASA Astrophysics Data System (ADS)

    Harrison, Edward

    2011-11-01

    Preface; Introducing the masks; Part I. Worlds in the Making: 1. The magic Universe; 2. The mythic Universe; 3. The geometric Universe; 4. The medieval Universe; 5. The infinite Universe; 6. The mechanistic Universe; Part II. The Heart Divine: 7. Dance of the atoms and waves; 8. Fabric of space and time; 9. Nearer to the heart's desire; 10. The cosmic tide; 11. Do dreams ever come true?; Part III. The Cloud of Unknowing: 12. The witch universe; 13. The spear of Archytas; 14. All that is made; 15. The cloud of unknowing; 16. Learned ignorance.

  16. A Masked Photocathode in Photoinjector

    SciTech Connect

    Qiang, Ji

    2010-12-14

    In this paper, we propose a masked photocathode inside the photoinjector for generating high brightness election beam. Instead of mounting the photocathode onto an electrode, an electrode with small hole is used as a mask to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material easy by rotating the photocathode behind the electrode into the hole. Furthermore, this helps reduce the dark current or secondary electron emission from the photocathode material. The masked photocathode also provides transverse cut-off to a Gaussian laser beam that reduces electron beam emittance growth from nonlinear space-charge effects.

  17. Optical inspection of NGL masks

    NASA Astrophysics Data System (ADS)

    Pettibone, Donald W.; Stokowski, Stanley E.

    2004-12-01

    For the last five years KLA-Tencor and our joint venture partners have pursued a research program studying the ability of optical inspection tools to meet the inspection needs of possible NGL lithographies. The NGL technologies that we have studied include SCALPEL, PREVAIL, EUV lithography, and Step and Flash Imprint Lithography. We will discuss the sensitivity of the inspection tools and mask design factors that affect tool sensitivity. Most of the work has been directed towards EUV mask inspection and how to optimize the mask to facilitate inspection. Our partners have succeeded in making high contrast EUV masks ranging in contrast from 70% to 98%. Die to die and die to database inspection of EUV masks have been achieved with a sensitivity that is comparable to what can be achieved with conventional photomasks, approximately 80nm defect sensitivity. We have inspected SCALPEL masks successfully. We have found a limitation of optical inspection when applied to PREVAIL stencil masks. We have run inspections on SFIL masks in die to die, reflected light, in an effort to provide feedback to improve the masks. We have used a UV inspection system to inspect both unpatterned EUV substrates (no coatings) and blanks (with EUV multilayer coatings). These inspection results have proven useful in driving down the substrate and blank defect levels.

  18. Enabling the 22nm node via grazing incidence collectors integrated into the DPP source for EUVL HVM

    NASA Astrophysics Data System (ADS)

    Bianucci, G.; Bragheri, A.; Cassol, G. L.; Ghislanzoni, R.; Mazzoleni, R.; Zocchi, F. E.

    2011-04-01

    Media Lario Technologies (MLT) has enabled the Extreme Ultraviolet Lithography (EUVL) roadmap with its grazing incidence collectors installed in all DPP sources since 2006. Furthermore, with several 100 WIF capable production grazing incidence collectors shipped in 2010, MLT is ready to support the start of High Volume Manufacturing (HVM). With a point-source collection efficiency of 25% and 6 kW power loading capability, the 9-shell collector design is capable of delivering 100 W in-band EUV power through the intermediate focus aperture. The customized reflective layer and the debris mitigation technology enable the 1-year lifetime objective under full production operating conditions. Integration of the grazing incidence collector in XTREME technologies' (XT) DPP source attached to ASML's NXE:3100 scanner has provided initial validation of the optical, thermal, and lifetime design objectives. In full HVM regime, we anticipate that the collector power loading will progressively reach 20 kW to enable 500 W inband EUV peak power at intermediate focus. We have started the development of a thermal management design maintaining the current optical stability with a collector power loading of 30 kW, thus meeting the aggressive HVM requirements.

  19. The implementation of Mask-Ed: reflections of academic participants.

    PubMed

    Reid-Searl, Kerry; Levett-Jones, Tracy; Cooper, Simon; Happell, Brenda

    2014-09-01

    This paper profiles the findings from a study that explored the perspectives and experiences of nurse educators who implemented a novel simulation approach termed Mask-Ed. The technique involves the educator wearing a silicone mask and or body parts and transforming into a character. The premise of this approach is that the masked educator has domain specific knowledge related to the simulation scenario and can transmit this to learners in a way that is engaging, realistic, spontaneous and humanistic. Nurse educators charged with the responsibility of implementing Mask-Ed in three universities were invited to participate in the study by attending an introductory workshop, implementing the technique and then journaling their experiences, insights and perspectives over a 12 month period. The journal entries were then thematically analysed. Key themes were categorised under the headings of Preparation, Implementation and Impact; Reflexivity and Responsiveness; Student Engagement and Ownership; and Teaching and Learning. Mask-Ed is a simulation approach which allows students to interact with the 'characters' in humanistic ways that promote person-centred care and therapeutic communication. This simulation approach holds previously untapped potential for a range of learning experiences, however, to be effective, adequate resourcing, training, preparation and practice is required. PMID:24906681

  20. What Is Being Masked in Object Substitution Masking?

    ERIC Educational Resources Information Center

    Gellatly, Angus; Pilling, Michael; Cole, Geoff; Skarratt, Paul

    2006-01-01

    Object substitution masking (OSM) is said to occur when a perceptual object is hypothesized that is mismatched by subsequent sensory evidence, leading to a new hypothesized object being substituted for the first. For example, when a brief target is accompanied by a longer lasting display of nonoverlapping mask elements, reporting of target…

  1. EFFECT OF MASKED REGIONS ON WEAK-LENSING STATISTICS

    SciTech Connect

    Shirasaki, Masato; Yoshida, Naoki; Hamana, Takashi

    2013-09-10

    Sky masking is unavoidable in wide-field weak-lensing observations. We study how masks affect the measurement of statistics of matter distribution probed by weak gravitational lensing. We first use 1000 cosmological ray-tracing simulations to examine in detail the impact of masked regions on the weak-lensing Minkowski Functionals (MFs). We consider actual sky masks used for a Subaru Suprime-Cam imaging survey. The masks increase the variance of the convergence field and the expected values of the MFs are biased. The bias then compromises the non-Gaussian signals induced by the gravitational growth of structure. We then explore how masks affect cosmological parameter estimation. We calculate the cumulative signal-to-noise ratio (S/N) for masked maps to study the information content of lensing MFs. We show that the degradation of S/N for masked maps is mainly determined by the effective survey area. We also perform simple {chi}{sup 2} analysis to show the impact of lensing MF bias due to masked regions. Finally, we compare ray-tracing simulations with data from a Subaru 2 deg{sup 2} survey in order to address if the observed lensing MFs are consistent with those of the standard cosmology. The resulting {chi}{sup 2}/n{sub dof} = 29.6/30 for three combined MFs, obtained with the mask effects taken into account, suggests that the observational data are indeed consistent with the standard {Lambda}CDM model. We conclude that the lensing MFs are a powerful probe of cosmology only if mask effects are correctly taken into account.

  2. Effect of Masked Regions on Weak-lensing Statistics

    NASA Astrophysics Data System (ADS)

    Shirasaki, Masato; Yoshida, Naoki; Hamana, Takashi

    2013-09-01

    Sky masking is unavoidable in wide-field weak-lensing observations. We study how masks affect the measurement of statistics of matter distribution probed by weak gravitational lensing. We first use 1000 cosmological ray-tracing simulations to examine in detail the impact of masked regions on the weak-lensing Minkowski Functionals (MFs). We consider actual sky masks used for a Subaru Suprime-Cam imaging survey. The masks increase the variance of the convergence field and the expected values of the MFs are biased. The bias then compromises the non-Gaussian signals induced by the gravitational growth of structure. We then explore how masks affect cosmological parameter estimation. We calculate the cumulative signal-to-noise ratio (S/N) for masked maps to study the information content of lensing MFs. We show that the degradation of S/N for masked maps is mainly determined by the effective survey area. We also perform simple χ2 analysis to show the impact of lensing MF bias due to masked regions. Finally, we compare ray-tracing simulations with data from a Subaru 2 deg2 survey in order to address if the observed lensing MFs are consistent with those of the standard cosmology. The resulting χ2/n dof = 29.6/30 for three combined MFs, obtained with the mask effects taken into account, suggests that the observational data are indeed consistent with the standard ΛCDM model. We conclude that the lensing MFs are a powerful probe of cosmology only if mask effects are correctly taken into account.

  3. Masked Proportional Routing

    NASA Technical Reports Server (NTRS)

    Wolpert, David

    2004-01-01

    Masked proportional routing is an improved procedure for choosing links between adjacent nodes of a network for the purpose of transporting an entity from a source node ("A") to a destination node ("B"). The entity could be, for example, a physical object to be shipped, in which case the nodes would represent waypoints and the links would represent roads or other paths between waypoints. For another example, the entity could be a message or packet of data to be transmitted from A to B, in which case the nodes could be computer-controlled switching stations and the links could be communication channels between the stations. In yet another example, an entity could represent a workpiece while links and nodes could represent, respectively, manufacturing processes and stages in the progress of the workpiece towards a finished product. More generally, the nodes could represent states of an entity and the links could represent allowed transitions of the entity. The purpose of masked proportional routing and of related prior routing procedures is to schedule transitions of entities from their initial states ("A") to their final states ("B") in such a manner as to minimize a cost or to attain some other measure of optimality or efficiency. Masked proportional routing follows a distributed (in the sense of decentralized) approach to probabilistically or deterministically choosing the links. It was developed to satisfy a need for a routing procedure that 1. Does not always choose the same link(s), even for two instances characterized by identical estimated values of associated cost functions; 2. Enables a graceful transition from one set of links to another set of links as the circumstances of operation of the network change over time; 3. Is preferably amenable to separate optimization of different portions of the network; 4. Is preferably usable in a network in which some of the routing decisions are made by one or more other procedure(s); 5. Preferably does not cause an

  4. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia; Hughes, Greg

    2008-04-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. This year's survey data were presented in detail at BACUS and the detailed trend analysis presented at EMLC. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the sixth in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments on critical path issues. This year's survey is basically the same as the 2005 and 2006 surveys. Questions are grouped into eight categories: General Business Profile Information, Data Processing, Yields and Yield Loss, Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that creates a detailed profile of both the business and technical status of the critical mask industry. Note: the questions covering operating cost factors and equipment utilization were added to the survey only in 2005; therefore, meaningful trend analysis is not available.

  5. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2009-01-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH to gather information about the mask industry as an objective assessment of its overall condition. This year's survey data were presented in detail at BACUS and the detailed trend analysis presented at EMLC. The survey is designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the seventh in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments on critical path issues. This year's survey is basically the same as the surveys in 2005 through 2007. Questions are grouped into seven categories: General Business Profile Information, Data Processing, Yields and Yield Loss, Mechanisms, Delivery Times, Returns, and Services. (Examples are given below). Within each category is a multitude of questions that creates a detailed profile of both the business and technical status of the critical mask industry.

  6. Combining Simultaneous with Temporal Masking

    ERIC Educational Resources Information Center

    Hermens, Frouke; Herzog, Michael H.; Francis, Gregory

    2009-01-01

    Simultaneous and temporal masking are two frequently used techniques in psychology and vision science. Although there are many studies and theories related to each masking technique, there are no systematic investigations of their mutual relationship, even though both techniques are often applied together. Here, the authors show that temporal…

  7. Masked Repetition Priming Using Magnetoencephalography

    ERIC Educational Resources Information Center

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David

    2008-01-01

    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  8. Advanced Mask Aligner Lithography (AMALITH)

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna

    2015-03-01

    Mask aligner lithography is very attractive for less-critical lithography layers and is widely used for LED, display, CMOS image sensor, micro-fluidics and MEMS manufacturing. Mask aligner lithography is also a preferred choice the semiconductor back-end for 3D-IC, TSV interconnects, advanced packaging (AdP) and wafer-level-packaging (WLP). Mask aligner lithography is a mature technique based on shadow printing and has not much changed since the 1980s. In shadow printing lithography a geometric pattern is transferred by free-space propagation from a photomask to a photosensitive layer on a wafer. The inherent simplicity of the pattern transfer offers ease of operation, low maintenance, moderate capital expenditure, high wafers-per-hour (WPH) throughput, and attractive cost-of-ownership (COO). Advanced mask aligner lithography (AMALITH) comprises different measures to improve shadow printing lithography beyond current limits. The key enabling technology for AMALITH is a novel light integrator systems, referred to as MO Exposure Optics® (MOEO). MOEO allows to fully control and shape the properties of the illumination light in a mask aligner. Full control is the base for accurate simulation and optimization of the shadow printing process (computational lithography). Now photolithography enhancement techniques like customized illumination, optical proximity correction (OPC), phase masks (AAPSM), half-tone lithography and Talbot lithography could be used in mask aligner lithography. We summarize the recent progress in advanced mask aligner lithography (AMALITH) and discuss possible measures to further improve shadow printing lithography.

  9. Optimal mask characterization by Surrogate Wafer Print (SWaP) method

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.; Hoellein, Ingo; Peters, Jan Hendrick; Ackmann, Paul; Connolly, Brid; West, Craig

    2008-10-01

    enhancement to mask characterization quality including defectivity, dimensional control, pattern fidelity, and in-plane distortion. We present a thorough analysis of both the technical and logistical challenges coupled with an objective view of the advantages and disadvantages from both the technical and financial perspectives. The analysis and model used by the AMTC will serve to provoke other mask shops to prepare their own analyses then consider this new paradigm for mask characterization and qualification.

  10. Defect tolerant transmission lithography mask

    DOEpatents

    Vernon, Stephen P.

    2000-01-01

    A transmission lithography mask that utilizes a transparent substrate or a partially transparent membrane as the active region of the mask. A reflective single layer or multilayer coating is deposited on the membrane surface facing the illumination system. The coating is selectively patterned (removed) to form transmissive (bright) regions. Structural imperfections and defects in the coating have negligible effect on the aerial image of the mask master pattern since the coating is used to reflect radiation out of the entrance pupil of the imaging system. Similarly, structural imperfections in the clear regions of the membrane have little influence on the amplitude or phase of the transmitted electromagnetic fields. Since the mask "discards," rather than absorbs, unwanted radiation, it has reduced optical absorption and reduced thermal loading as compared to conventional designs. For EUV applications, the mask circumvents the phase defect problem, and is independent of the thermal load during exposure.