Dr. Neal V. Lafferty Profile

Dr. Neal V. Lafferty

SPIE Involvement:

Conference Chair | Editor | Author

Area of Expertise:

lithography , optical proximity correction , source mask optimization

Publications (47)

Proceedings Article | 28 April 2023 Paper

EUV full-chip curvilinear mask options for logic via and metal patterning

Neal Lafferty, Sagar Saxena, Keisuke Mizuuchi, Yuansheng Ma, Xima Zhang, Pat LaCour, Alexander Tritchkov, Farah Kmiec, John Sturtevant

Proceedings Volume 12495, 124950K (2023) https://doi.org/10.1117/12.2647882

KEYWORDS: SRAF, Optical proximity correction, Machine learning, Lithography, Simulations

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Proceedings Article | 28 April 2023 Presentation + Paper

Application of resolution enhancement techniques at high NA EUV for next generation DRAM patterning

Ana-Maria Armeanu, Evgeny Malankin, Neal Lafferty, Chih-I Wei, Monica Kempsell Sears, Germain Fenger, Xima Zhang, Werner Gillijns, Darko Trivkovic, Ryoung-han Kim, Jeonghoon Lee

Proceedings Volume 12495, 124950A (2023) https://doi.org/10.1117/12.2660413

KEYWORDS: Photomasks, Extreme ultraviolet, Source mask optimization, Resolution enhancement technologies, Optical proximity correction, Lithography, Optical lithography, Capacitors, Semiconducting wafers, SRAF

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Among several critical layers of DRAM (dynamic random-access memory), capacitor holes of honeycomb arrays and bit-line-periphery (BLP) with Storage Node Landing Pad (SNLP) are the most critical layers in terms of patterning difficulty level. The honeycomb array hole layer has the highest density among various hole array types, and it is a complex lithography step since this layer is key in determining the performance of the DRAM. BLP with SNLP includes hole type and bi-directional line/space (L/S) design, and industry is considering a single exposure solution, compared to a three-mask solution using ArF immersion [1]. This BLP layer of 10nm DRAM has 2 different types of pattern topologies, hole array and bi-direction line/space: it is a very challenging single exposure level. In this paper, we discuss patterning challenges that come as consequences of industry trends in DRAM cell size reduction [2,3]. To keep up with this trend and to propose a single mask solution for bit-line-periphery, storage node landing pads and aggressive cell array pitches are considered along with resolution enhancement techniques (RET) for high-NA anamorphic EUV (NA=0.55) lithography. This study uses computational lithography such as source mask optimization (SMO) to find optimal off-axis illumination and optimal placement of sub-resolution assist features (SRAF) on the mask whilst considering the manufacturing rules checks (MRC constraints) for anamorphic EUV masks. In order to achieve that, a screening Design Technology Co-optimization (DTCO) experiment is done. The purpose is to identify cell array pitches in between 24nm and 32nm which satisfy both scaling requirements and patterning fidelity, preferred orientation of layout, and mask biasing scheme for various cell arrays. Lithography metrics like common depth of focus (cDoF), exposure latitude (EL), image contrast, and image log slope (ILS) are used to decide what is optimal way to expose on wafer. For the sake of completeness of the study, mask materials are compared. Indeed, in EUV domain there is interest to use alternative mask absorbers like Ruthenium alloys as an alternative to Tantalum-based absorbers [4,5,6].

Proceedings Article | 28 April 2023 Paper

Patterning assessment using 0.33NA EUV single mask for next generation DRAM manufacturing

Jeonghoon Lee, Sandip Halder, Van Tuong Pham, Roberto Fallica, Seonggil Heo, Kaushik Sah, Hyo Seon Suh, Victor Blanco, Werner Gillijns, Andrew Cross, Ethan Maguire, Ana-Maria Armeanu, Vladislav Liubich, Evgeny Malankin, Xima Zhang, Monica Kempsell Sears, Neal Lafferty, Germain Fenger, Chih-I Wei, Ryoung Han Kim

Proceedings Volume 12495, 124950S (2023) https://doi.org/10.1117/12.2660763

KEYWORDS: Optical lithography, Extreme ultraviolet, Optical proximity correction, Design and modelling, SRAF, Semiconducting wafers, Inspection, Source mask optimization, Printing, Electronic design automation

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Proceedings Article | 28 April 2023 Poster + Paper

Impact of mask rule constraints on ideal SRAF placement

Monica Kempsell Sears, Farah Huq Kmiec, Neal Lafferty, John Sturtevant

Proceedings Volume 12494, 124941C (2023) https://doi.org/10.1117/12.2657767

KEYWORDS: SRAF, Printing, Extreme ultraviolet, Deep ultraviolet, Image quality, Lithography

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Proceedings Article | 1 December 2022 Poster + Paper

Single mask solution to pattern BLP and SNLP using 0.33NA EUV for next-generation DRAM manufacturing

Kaushik Sah, Andrew Cross, Sayantan Das, Roberto Fallica, Jeonghoon Lee, Ryoung-Han Kim, Sandip Halder, Ethan Maguire, Ana-Maria Armeanu, Monica Sears, Neal Lafferty, Vlad Liubich, Chih-i Wei, Germain Fenger

Proceedings Volume 12292, 122920W (2022) https://doi.org/10.1117/12.2645953

KEYWORDS: Photomasks, Optical proximity correction, Stochastic processes, Extreme ultraviolet, Semiconducting wafers, Wafer-level optics, Source mask optimization, Manufacturing, Inspection, Signal to noise ratio, Defect inspection

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Proceedings Article | 26 May 2022 Presentation + Paper

Spectrum optimization during SMO: simultaneous source-mask-laser spectrum optimization

Evgeny Malankin, Neal Lafferty, Mikhail Silakov, Ekaterina Semenova, Takamitsu Komaki, Kouichi Fujii, Taisuke Miura, Gouta Niimi, Taku Yamazaki

Proceedings Volume 12052, 1205205 (2022) https://doi.org/10.1117/12.2614055

KEYWORDS: Source mask optimization, Electroluminescence, Metals, Photomasks, Light sources, Logic, SRAF, Lithography, Chromatic aberrations, Excimer lasers

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Tuning the spectrum of a scanner’s excimer laser light source is a well-known technique to achieve improved depth of focus (DOF) for an exposure. Previous studies have focused on the imaging improvement capabilities of readily available spectral shapes such as Gaussian E95 single peak width, as well as dual-peak spectral shapes where the spacing of the peaks can be varied. It is commonly known that adjustments in the laser spectrum must be carefully considered since exposure latitude (EL) can also be reduced as DOF is increased. By carefully engineering the laser’s spectrum, DOF can be maximized with very little impact to exposure latitude. Undesirable speckle contrast can also be reduced as laser bandwidth is increased. Traditionally, these approaches have been used to improve DOF of thick resist applications such as CMOS image sensors. Other areas such as NAND Flash have introduced laser spectrum engineering (SE) to compensate for topography effects between periphery and array regions. Recently, advances in laser hardware have enabled new and unique spectral shapes to be used for imaging. In this paper, we explore the various spectral profiles possible on the latest Gigaphoton GT66A ArFi light sources. New applications of these spectrum shapes are considered for foundry logic-type levels. First, a representative 14nm-node logic layer is considered. Source Mask Optimization (SMO) is performed while various widths of spectral profiles are used as input, such as traditional E95 Gaussian profiles, dual-peak, and flat top. By accounting for the laser spectrum during SMO, common DOF can be improved by ≥ 20% without a noticeable decrease in exposure latitude. The SMO sources and optimized masks are also different from each other and the nominal cases, depending on the spectral distribution used. Next, we explore simultaneously optimizing the laser spectrum, source, and mask in an experimental SMO+SE. Spectra can be constrained to keep symmetric profiles about the 193nm center point. Improved lithographic performance can result from the application of programmable laser spectra combined with pixelated sources and inverse lithography (ILT).

Proceedings Article | 25 May 2022 Presentation + Paper

EUV based multi-patterning schemes for advanced DRAM nodes

Sayantan Das, Kaushik Sah, Roberto Fallica, Zhijin Chen, Sandip Halder, Andrew Cross, Danilo De Simone, Fergo Treska, Philippe Leray, Ryoung Han Kim, Ethan Maguire, Chih-I Wei, Germain Fenger, Neal Lafferty, Jeonghoon Lee

Proceedings Volume 12055, 1205503 (2022) https://doi.org/10.1117/12.2615644

KEYWORDS: Etching, Photomasks, Extreme ultraviolet, Optical lithography, Double patterning technology

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Proceedings Article | 26 September 2019 Paper

Exploring alternative EUV mask absorber for iN5 self-aligned block and contact layers

Rajiv Sejpal, Vicky Philipsen, Ana Armeanu, Chih-I Wei, Werner Gillijns, Neal Lafferty, Germain Fenger, Eric Hendrickx

Proceedings Volume 11148, 111481B (2019) https://doi.org/10.1117/12.2536892

KEYWORDS: Photomasks, Extreme ultraviolet, Extreme ultraviolet lithography, Lithography, Source mask optimization, Nanoimprint lithography, SRAF, Optical proximity correction, Phase shifting, Logic

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Proceedings Article | 2 January 2019 Presentation + Paper

Enabling enhanced EUV lithographic performance using advanced SMO, OPC, and RET

Ana Armeanu, Vicky Philipsen, Fan Jiang, Germain Fenger, Neal Lafferty, Werner Gillijns, Eric Hendrickx, John Sturtevant

Proceedings Volume 10809, 108090G (2019) https://doi.org/10.1117/12.2502809

KEYWORDS: Photomasks, Extreme ultraviolet, Source mask optimization, Resolution enhancement technologies, Tantalum, SRAF, Lithography, Logic, Image enhancement, Image processing

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The current industry standard tantalum-based mask absorber (60 nm TaBN) gives strong 3D electromagnetic field (EMF) effects at wafer level, such as shadowing and pitch-dependent best focus shifts. A thinner mask absorber with higher EUV extinction coefficient or a phase shifting mask can mitigate 3D EMF effects [1]. The alternative mask absorber materials would enable further downscaling to foundry 5nm node using state-of-the-art EUV scanners (with 0.33 numerical aperture “NA”) and facilitate future high NA imaging using single exposure. Here we evaluate insertion options on the patterning roadmap for alternative EUV mask absorbers, including high-k absorbers and attenuated phase shifting masks (attPSM) [1-2]. All studies are using relevant designs from foundry N5 logic node. Two alternative mask candidates are compared with the standard TaBN mask. We bring theoretical proof of concept that alternative mask absorber materials generate significant imaging gain in terms of established success criteria. On a set of predefined types of clips (with variations of 1D/2D, horizontal/vertical, dense/isolated patterns), we seek for higher depth of focus (DoF), higher image log slope (ILS), high illumination efficiency (ideally it would be equal to 1), lower pattern shift through focus (i.e., lower tele-centricity errors), lower mask error enhancement factor (MEEF). Source mask optimization (SMO) on N5 logic clip shows a more balanced source and larger common process window for high-k absorber over Ta-based absorber. Using the optical proximity correction (OPC) engine with high-k mask absorber, shows significant gain on overlapping process window (PW), process variation (PV) band, and less line end shortening. Applying advanced Resolution Enhancement Techniques (RET), sub-resolution assist features (SRAFs) on N5 designs demonstrated an improved process in terms of common depth of focus (cDoF), and image shift through focus. It was also observed that the process not using SRAFs with the high-k absorber had superior process window and image shift compared to the Ta-based case with SRAFs. Therefore, adoption of such high-k absorbers could potentially postpone the need for SRAFs.

Proceedings Article | 20 March 2018 Paper

Exploring EUV and SAQP pattering schemes at 5nm technology node

Ahmed Hamed Fatehy, Rehab Kotb, Neal Lafferty, Fan Jiang, James Word

Proceedings Volume 10583, 105831X (2018) https://doi.org/10.1117/12.2297408

KEYWORDS: Extreme ultraviolet, Optical proximity correction, Optical lithography, Photomasks, Source mask optimization, Deep ultraviolet, Printing, Manufacturing, Metals, Image processing

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For years, Moore’s law keeps driving the semiconductors industry towards smaller dimensions and higher density chips with more devices. Earlier, the correlation between exposure source’s wave length and the smallest resolvable dimension, mandated the usage of Deep Ultra-Violent (DUV) optical lithography system which has been used for decades to sustain Moore’s law, especially when immersion lithography was introduced with 193nm ArF laser sources. As dimensions of devices get smaller beyond Deep Ultra-Violent (DUV) optical resolution limits, the need for Extremely Ultra-Violent (EUV) optical lithography systems was a must. However, EUV systems were still under development at that time for the mass-production in semiconductors industry. Theretofore, Multi-Patterning (MP) technologies was introduced to swirl about DUV optical lithography limitations in advanced nodes beyond minimum dimension (CD) of 20nm. MP can be classified into two main categories; the first one is to split the target itself across multiple masks that give the original target patterns when they are printed. This category includes Double, Triple and Quadruple patterning (DP, TP, and QP). The second category is the Self-Aligned Patterning (SAP) where the target is divided into Mandrel patterns and non-Mandrel patterns. The Mandrel patterns get printed first, then a self-aligned sidewalls are grown around these printed patterns drawing the other non-Mandrel targets, afterword, a cut mask(s) is used to define target’s line-ends. This approach contains Self-Aligned-Double Pattering (SADP) and Self-Aligned- Quadruple-Pattering (SAQP). DUV and MP along together paved the way for the industry down to 7nm. However, with the start of development at the 5nm node and the readiness of EUV, the differentiation question is aroused again, which pattering approach should be selected, direct printing using EUV or DUV with MP, or a hybrid flow that contains both DUV-MP and EUV.

In this work we are comparing two potential pattering techniques for Back End Of Line (BEOL) metal layers in the 5nm technology node, the first technique is Single Exposure EUV (SE-EUV) with a Direct Patterning EUV lithography process, and the second one is Self-Aligned Quadruple Patterning (SAQP) with a hybrid lithography processes, where the drawn metal target layer is decomposed into a Mandrel mask and Blocks/Cut mask, Mandrel mask is printed using DUV 193i lithography process, while Block/Cut Mask is printed using SE-EUV lithography process. The pros and cons of each technique are quantified based on Edge-Placement-Error (EPE) and Process Variation Band (PVBand) measured at 1D and 2D edges. The layout used in this comparison is a candidate layout for Foundries 5nm process node.

Proceedings Article | 20 March 2018 Paper

Ultimate patterning limits for EUV at 5nm node and beyond

Rehab Kotb Ali, Ahmed Hamed Fatehy, Neal Lafferty, James Word

Proceedings Volume 10583, 1058321 (2018) https://doi.org/10.1117/12.2297412

KEYWORDS: Metals, Source mask optimization, Extreme ultraviolet, Optical proximity correction, Optical lithography, Manufacturing, Printing, Extreme ultraviolet lithography, Image processing, Image quality

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Proceedings Article | 19 March 2018 Presentation + Paper

Impact of aberrations in EUV lithography: metal to via edge placement control

Lianghong Yin, Ananthan Raghunathan, Germain Fenger, Shumay Shang, Neal Lafferty, John Sturtevant

Proceedings Volume 10583, 105830Q (2018) https://doi.org/10.1117/12.2299872

KEYWORDS: Metals, Optical proximity correction, Scanners, Extreme ultraviolet lithography, Manufacturing, Overlay metrology, Bridges, Optical lithography, Logic, Photomasks

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Proceedings Article | 24 March 2017 Presentation + Paper

Enhanced OPC recipe coverage and early hotspot detection through automated layout generation and analysis

Ayman Hamouda, Mohamed Bahnas, Dan Schumacher, Ioana Graur, Ao Chen, Kareem Madkour, Hussein Ali, Jason Meiring, Neal Lafferty, Chris McGinty

Proceedings Volume 10147, 101470R (2017) https://doi.org/10.1117/12.2260769

KEYWORDS: Optical proximity correction, Optical lithography, Semiconductor manufacturing, Photomasks, Computational lithography, Databases, Resolution enhancement technologies, Visualization, Semiconducting wafers, Design for manufacturing, Cadmium

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Proceedings Article | 15 March 2016 Paper

Source mask optimization study based on latest Nikon immersion scanner

Jun Zhu, Fang Wei, Lijun Chen, Chenming Zhang, Wei Zhang, Hisashi Nishinaga, Omar El-Sewefy, Gen-Sheng Gao, Neal Lafferty, Jason Meiring, Recoo Zhang, Cynthia Zhu

Proceedings Volume 9780, 97801P (2016) https://doi.org/10.1117/12.2223576

KEYWORDS: Source mask optimization, Scanners, Photomasks, Fiber optic illuminators, Logic, Lithography, Semiconducting wafers, Visualization, SRAF, Back end of line

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Proceedings Article | 15 March 2016 Paper

Source mask optimization using 3D mask and compact resist models

Omar El-Sewefy, Ao Chen, Neal Lafferty, Jason Meiring, Angeline Chung, Yee Mei Foong, Kostas Adam, John Sturtevant

Proceedings Volume 9780, 978019 (2016) https://doi.org/10.1117/12.2220011

KEYWORDS: 3D modeling, Source mask optimization, Photomasks, Performance modeling, Optical proximity correction, Lithography, Optimization (mathematics), Algorithm development, Computational lithography, Superposition, Nanoimprint lithography, Image processing, Data modeling

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Source Mask Optimization (SMO) has played an important role in technology setup and ground rule definition since the 2x nm technology node. While improvements in SMO algorithms have produced higher quality and more consistent results, the accuracy of the overall solution is critically linked to how faithfully the entire patterning system is modeled, from mask down to substrate. Fortunately, modeling technology has continued to advance to provide greater accuracy in modeling 3D mask effects, 3D resist behavior, and resist phenomena. Specifically, the Domain Decomposition Method (DDM) approximates the 3D mask response as a superposition of edge-responses.¹ The DDM can be applied to a sectorized illumination source based on Hybrid-Hopkins Abbe approximation,² which provides an accurate and fast solution for the modeling of 3D mask effects and has been widely used in OPC modeling. The implementation of DDM in the SMO flow, however, is more challenging because the shape and intensity of the source, unlike the case in OPC modeling, is evolving along the optimization path. As a result, it gets more complicated. It is accepted that inadequate pupil sectorization results in reduced accuracy in any application, however in SMO the required uniformity and density of pupil sampling is higher than typical OPC and modeling cases. In this paper, we describe a novel method to implement DDM in the SMO flow. The source sectorization is defined by following the universal pixel sizes used in SMO. Fast algorithms are developed to enable computation of edge signals from each fine pixel of the source. In this case, each pixel has accurate information to describe its contribution to imaging and the overall objective function. A more continuous angular spectrum from 3D mask scattering is thus captured, leading to accurate modeling of 3D mask effects throughout source optimization. This method is applied on a 2x nm middle-of-line layer test case. The impact of the 3D mask model accuracy on the source profile and corresponding lithographic performance is studied in detail. Furthermore, the impact of using a compact resist model in SMO is also investigated by using the same test case.

SPIE Journal Paper | 11 September 2015

Directed self-assembly graphoepitaxy template generation with immersion lithography

Yuansheng Ma, Junjiang Lei, J. Andres-Torres, Le Hong, James Word, Germain Fenger, Alexander Tritchkov, George Lippincott, Rachit Gupta, Neal Lafferty, Yuan He, Joost Bekaert, Geert Vanderberghe

JM3, Vol. 14, Issue 03, 031216, (September 2015) https://doi.org/10.1117/12.10.1117/1.JMM.14.3.031216

KEYWORDS: Dysprosium, Photomasks, Immersion lithography, Source mask optimization, Optical proximity correction, Printing, Optical lithography, Visualization, Lens design, Directed self assembly

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Proceedings Article | 19 March 2015 Paper

Directed self-assembly (DSA) grapho-epitaxy template generation with immersion lithography

Yuansheng Ma, Junjiang Lei, J. Torres, Le Hong, James Word, Germain Fenger, Alexander Tritchkov, George Lippincott, Rachit Gupta, Neal Lafferty, Yuan He, Joost Bekaert, Geert Vanderberghe

Proceedings Volume 9423, 942306 (2015) https://doi.org/10.1117/12.2085850

KEYWORDS: Photomasks, Optical proximity correction, Printing, Source mask optimization, Optical lithography, Neodymium, Visualization, Transmission electron microscopy, Dysprosium, Directed self assembly

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Proceedings Article | 18 March 2015 Paper

Practical DTCO through design/patterning exploration

Neal Lafferty, Jason Meiring, Mohamed Bahnas, Joseph O'Neill, Toshikazu Endo, Dan Schumacher, James Culp, Glenn Wawrzynski, Gurpreet Lamba, Kostas Adam, John Sturtevant, Chris McGinty

Proceedings Volume 9427, 942710 (2015) https://doi.org/10.1117/12.2086355

KEYWORDS: Optical proximity correction, Optical lithography, Visualization, Photovoltaics, Legal, Resolution enhancement technologies, Manufacturing, Aerospace engineering, Metals, Databases

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Proceedings Article | 18 March 2015 Paper

RET selection on state-of-the-art NAND flash

Neal Lafferty, Yuan He, Jinhua Pei, Feng Shao, QingWei Liu, Xuelong Shi

Proceedings Volume 9426, 94260L (2015) https://doi.org/10.1117/12.2087176

KEYWORDS: Source mask optimization, Resolution enhancement technologies, Photomasks, Lithography, Optical proximity correction, Nanoimprint lithography, SRAF, Optical lithography, Photovoltaics, Visualization

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Proceedings Article | 29 October 2014 Paper

Full-flow RET creation, comparison, and selection

Neal Lafferty, Yuan He, Mikhail Silakov, Toshi Endo, Kostas Adam

Proceedings Volume 9235, 92351Z (2014) https://doi.org/10.1117/12.2069473

KEYWORDS: Resolution enhancement technologies, Source mask optimization, Photomasks, Optical lithography, Lithography, Optical proximity correction, Photovoltaics, Nanoimprint lithography, Visualization, Performance modeling

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Proceedings Article | 31 March 2014 Paper

Computational lithography platform for 193i-guided directed self-assembly

Kafai Lai, Melih Ozlem, Jed Pitera, Chi-chun Liu, Anthony Schepis, Daniel Dechene, Azalia Krasnoperova, Daniel Brue, Jassem Abdallah, Hsinyu Tsai, Mike Guillorn, Joy Cheng, Gregory Doerk, Melia Tjio, Rasit Topalogu, Moutaz Fakhry, Neal Lafferty

Proceedings Volume 9052, 90521A (2014) https://doi.org/10.1117/12.2046920

KEYWORDS: 3D modeling, Monte Carlo methods, Computational lithography, Photomasks, Critical dimension metrology, Lithography, Photoresist processing, Instrument modeling, Optical lithography, Directed self assembly

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Proceedings Article | 12 April 2013 Paper

Computational aspects of optical lithography extension by directed self-assembly

Kafai Lai, Chi-chun Liu, Jed Pitera, Daniel Dechene, Anthony Schepis, Jassem Abdallah, Hsinyu Tsai, Mike Guillorn, Joy Cheng, Gregory Doerk, Melia Tjio, Charles Rettner, Olalekan Odesanya, Melih Ozlem, Neal Lafferty

Proceedings Volume 8683, 868304 (2013) https://doi.org/10.1117/12.2012440

KEYWORDS: Photomasks, Optical lithography, Lithography, Optical proximity correction, Source mask optimization, 3D modeling, Extreme ultraviolet, Semiconducting wafers, Data modeling, Directed self assembly

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Proceedings Article | 21 March 2012 Paper

Progress towards the integration of optical proximity correction and directed self-assembly of block copolymers with graphoepitaxy

Chi-Chun Liu, Jed Pitera, Neal Lafferty, Kafai Lai, Charles Rettner, Melia Tjio, Noel Arellano, Joy Cheng

Proceedings Volume 8323, 83230X (2012) https://doi.org/10.1117/12.916525

KEYWORDS: Performance modeling, Monte Carlo methods, Optical proximity correction, Photomasks, Lithography, 3D modeling, Photoresist processing, Electron beam lithography, Double patterning technology, Directed self assembly

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Proceedings Article | 15 March 2012 Paper

Design and manufacturability tradeoffs in unidirectional and bidirectional standard cell layouts in 14 nm node

Kaushik Vaidyanathan, Siew Hoon Ng, Daniel Morris, Neal Lafferty, Lars Liebmann, Mitchell Bender, Wenbin Huang, Kafai Lai, Larry Pileggi, Andrzej Strojwas

Proceedings Volume 8327, 83270K (2012) https://doi.org/10.1117/12.916104

KEYWORDS: Manufacturing, Back end of line, Standards development, Metals, Design for manufacturability, Lithography, Logic, Optical lithography, Front end of line, Transistors

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Proceedings Article | 15 March 2012 Paper

Local loops for robust inter-layer routing at sub-20 nm nodes

Wenbin Huang, Daniel Morris, Neal Lafferty, Lars Liebmann, Kaushik Vaidyanathan, Kafai Lai, Larry Pileggi, Andrzej Strojwas

Proceedings Volume 8327, 83270D (2012) https://doi.org/10.1117/12.916290

KEYWORDS: Metals, Lithography, Solids, Failure analysis, Manufacturing, Resistance, SRAF, Capacitance, Electronic design automation, Yield improvement

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Proceedings Article | 16 April 2011 Paper

Development of an inorganic nanoparticle photoresist for EUV, e-beam, and 193nm lithography

Marie Krysak, Markos Trikeriotis, Evan Schwartz, Neal Lafferty, Peng Xie, Bruce Smith, Paul Zimmerman, Warren Montgomery, Emmanuel Giannelis, Christopher Ober

Proceedings Volume 7972, 79721C (2011) https://doi.org/10.1117/12.879385

KEYWORDS: Etching, Nanoparticles, Resistance, Oxides, Photoresist materials, Electron beam lithography, Hafnium, Lithography, Extreme ultraviolet lithography, Refractive index

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Proceedings Article | 16 April 2011 Paper

Sensitive polysulfone based chain scissioning resists for 193nm lithography

Yong Keng Goh, Lan Chen, Anneke Dorgelo, Xie Peng, Neal Lafferty, Bruce Smith, Paul Zimmerman, Warren Montgomery, Idriss Blakey, Andrew Whittaker

Proceedings Volume 7972, 79722E (2011) https://doi.org/10.1117/12.881700

KEYWORDS: Line edge roughness, Polymers, Absorbance, Water, Sulfur, Scanning electron microscopy, Lithography, Double patterning technology, 193nm lithography, Coating

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Proceedings Article | 26 March 2010 Paper

Development of an inorganic photoresist for DUV, EUV, and electron beam imaging

Markos Trikeriotis, Woo Jin Bae, Evan Schwartz, Marie Krysak, Neal Lafferty, Peng Xie, Bruce Smith, Paul Zimmerman, Christopher Ober, Emmanuel Giannelis

Proceedings Volume 7639, 76390E (2010) https://doi.org/10.1117/12.846672

KEYWORDS: Nanoparticles, Photoresist materials, Electron beam lithography, Etching, Hafnium, Resistance, Oxides, Photoresist developing, Deep ultraviolet, Refractive index

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Proceedings Article | 11 March 2010 Paper

Metamaterials for enhancement of DUV lithography

Andrew Estroff, Neal Lafferty, Peng Xie, Bruce Smith

Proceedings Volume 7640, 76402W (2010) https://doi.org/10.1117/12.848427

KEYWORDS: Surface plasmons, Aluminum, Deep ultraviolet, Dielectrics, Molybdenum, Metamaterials, Reflectivity, Refractive index, Tin, Reflection

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Proceedings Article | 10 March 2010 Paper

Achieving interferometric double patterning through wafer rotation

Peng Xie, Neal Lafferty, Bruce Smith

Proceedings Volume 7640, 76401Z (2010) https://doi.org/10.1117/12.848345

KEYWORDS: Double patterning technology, Semiconducting wafers, Interferometry, Optical alignment, Lithography, Materials processing, Imaging systems, Scanning electron microscopy, Optical lithography, Photomasks

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Proceedings Article | 15 April 2008 Paper

Development and evaluation of 193nm immersion generation-three fluid candidates

Paul Zimmerman, Jeffrey Byers, Bryan Rice, Christopher Ober, Emmanuel Giannelis, Robert Rodriguez, Dongyan Wang, Naphtali O’Connor, Xuegong Lei, Nicholas Turro, Vladimir Liberman, Stephen Palmacci, Mordechai Rothschild, Neal Lafferty, Bruce Smith

Proceedings Volume 6923, 69230A (2008) https://doi.org/10.1117/12.772887

KEYWORDS: Nanoparticles, Refractive index, Absorbance, Metals, Oxides, Water, Nanocomposites, Transparency, Polarizability, Ultraviolet radiation

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Proceedings Article | 29 March 2007 Paper

Mask enhancement using an evanescent wave effect

Neal Lafferty, Jianming Zhou, Bruce Smith

Proceedings Volume 6520, 652041 (2007) https://doi.org/10.1117/12.711781

KEYWORDS: Chromium, Photomasks, Near field, Lithography, Wave propagation, Refractive index, Polarization, Image enhancement, Resolution enhancement technologies, Finite-difference time-domain method

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Proceedings Article | 27 March 2007 Paper

Immersion lithography with numerical apertures above 2.0 using high index optical materials

Jianming Zhou, Neal Lafferty, Bruce Smith, John Burnett

Proceedings Volume 6520, 65204T (2007) https://doi.org/10.1117/12.712429

KEYWORDS: Photoresist materials, Refractive index, Absorbance, Sapphire, Optical lithography, Aluminum, Interfaces, Birefringence, Lutetium, Prisms

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Proceedings Article | 26 March 2007 Paper

On the quality of measured optical aberration coefficients using phase wheel monitor

Lena Zavyalova, Aaron Robinson, Anatoly Bourov, Neal Lafferty, Bruce Smith

Proceedings Volume 6520, 65203T (2007) https://doi.org/10.1117/12.721311

KEYWORDS: Wavefronts, Data modeling, Scanning electron microscopy, Monochromatic aberrations, Calibration, Image processing, Point spread functions, Photoresist materials, Semiconducting wafers, Visualization

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Proceedings Article | 15 March 2006 Paper

Evanescent wave imaging in optical lithography

Bruce Smith, Yongfa Fan, Jianming Zhou, Neal Lafferty, Andrew Estroff

Proceedings Volume 6154, 61540A (2006) https://doi.org/10.1117/12.657322

KEYWORDS: Wave propagation, Refractive index, Photoresist materials, Lithography, Optical lithography, Photomasks, Near field, Interfaces, Imaging systems, Solids

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Proceedings Article | 12 May 2005 Paper

Physically based compact models for fast lithography simulation

Neal Lafferty, Kostas Adam, Yuri Granik, Andres Torres, Wilhelm Maurer

Proceedings Volume 5754, (2005) https://doi.org/10.1117/12.599889

KEYWORDS: Process modeling, Lithography, Data modeling, Calibration, Resolution enhancement technologies, Error analysis, Semiconducting wafers, Photoresist processing, Optical proximity correction, Wafer-level optics

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Proceedings Article | 12 May 2005 Paper

ILSim: a compact simulation tool for interferometric lithography

Yongfa Fan, Anatoly Bourov, Lena Zavyalova, Jianming Zhou, Andrew Estroff, Neal Lafferty, Bruce Smith

Proceedings Volume 5754, (2005) https://doi.org/10.1117/12.621286

KEYWORDS: Polarization, Thin films, Interferometry, Reflection, Interfaces, Lithography, Imaging systems, Thin film coatings, Immersion lithography, Nanolithography

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Proceedings Article | 12 May 2005 Paper

Complementary dipole exposure solutions at 0.29 k1

Eric Hendrickx, Andres Torres, Neal Lafferty, Laurent Le Cam, Stephen Johnson, Carlo Reita, Geert Vandenberghe, Wilhelm Maurer

Proceedings Volume 5754, (2005) https://doi.org/10.1117/12.600843

KEYWORDS: Photomasks, Optical proximity correction, Reticles, Data modeling, Logic, Scanners, Optical lithography, Calibration, Semiconducting wafers, Oscillators

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Proceedings Article | 12 May 2005 Paper

Immersion lithography fluids for high NA 193 nm lithography

Jianming Zhou, Yongfa Fan, Anatoly Bourov, Neal Lafferty, Frank Cropanese, Lena Zavyalova, Andrew Estroff, Bruce Smith

Proceedings Volume 5754, (2005) https://doi.org/10.1117/12.602533

KEYWORDS: Refractive index, Absorbance, Microfluidics, Immersion lithography, Absorption, Water, Quartz, Prisms, Sodium, 193nm lithography

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Proceedings Article | 27 January 2005 Paper

Lithography yield enhancement through optical rule checking

James Word, J. Andres Torres, Thomas Roessler, Neal Lafferty, Shumay Shang

Proceedings Volume 5645, (2005) https://doi.org/10.1117/12.577609

KEYWORDS: Printing, Photomasks, Calibration, Lithography, Optical proximity correction, Scanning electron microscopy, Logic, Image processing, Data modeling, Process modeling

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Proceedings Article | 28 May 2004 Paper

Gray assist bar OPC

Neal Lafferty, Geert Vandenberghe, Bruce Smith, Matthew Lassiter, Patrick Martin

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.544244

KEYWORDS: Diffraction, Optical proximity correction, Reticles, Neodymium, Opacity, Diffraction gratings, Binary data, Manufacturing, SRAF, Lithography

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Proceedings Article | 28 May 2004 Paper

Study of air-bubble-induced light scattering effect on image quality in 193-nm immersion lithography

Yongfa Fan, Neal Lafferty, Anatoly Bourov, Lena Zavyalova, Bruce Smith

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.537255

KEYWORDS: Scattering, Mie scattering, Optical spheres, Light scattering, Water, Semiconducting wafers, Lithography, Laser scattering, Immersion lithography, Refractive index

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As an emerging technique, immersion lithography offers the capability of reducing critical dimensions by increasing numerical aperture (NA) due to the higher refractive indices of immersion liquids than that of air. Among the candidates for immersion liquids, water appears to be an excellent choice due to its high transparency at a wavelength of 193 nm, as well as its immediate availability and low processing cost. However, in the process of forming a water fluid layer between the resist and lens surfaces, air bubbles are often created due to the high surface tension of water. The presence of air bubbles in the immersion layer will degrade the image quality because of the inhomogeneity induced light scattering in the optical path. Therefore, it is essential to understand the air bubble induced light scattering effect on image quality. Analysis by geometrical optics indicates that the total reflection of light causes the enhancement of scattering in the region where the scattering angle is less than the critical scattering angle, which is 92 degrees at 193 nm. Based on Mie theory, numerical evaluation of scattering due to air bubbles, polystyrene spheres and PMMA spheres was conducted for TE, TM or unpolarized incident light. Comparison of the scattering patterns shows that the polystyrene spheres and air bubbles resemble each other with respect to scattering properties. Hence polystyrene spheres are used to mimic air bubbles in studies of lithographic imaging of “bubbles” in immersion water. In direct interference lithography, it is found that polystyrene spheres (2 μm in diameter) 0.3 mm away from the resist surface would not image, while for interferometric lithography at 0.5NA, this distance is estimated to be 1.3 mm. Surprisingly, polystyrene spheres in diameter of 0.5 μm (which is 5 times larger than the interferometric line-width) will not image. It is proposed that “bubbles” are repelled from contact with the resist film by surface tension. The scatter of exposure light can be characterized as “flare”. This work shows that microbubbles are not a technical barrier to immersion lithography.

Proceedings Article | 28 May 2004 Paper

Mask induced polarization

Andrew Estroff, Yongfa Fan, Anatoly Bourov, Frank Cropanese, Neal Lafferty, Lena Zavyalova, Bruce Smith

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.546423

KEYWORDS: Polarization, Photomasks, Binary data, Polarizers, Chromium, Dielectric polarization, Silica, Silicon, Phase shifts, Objectives

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Proceedings Article | 28 May 2004 Paper

Immersion microlithography at 193 nm with a Talbot prism interferometer

Anatoly Bourov, Yongfa Fan, Frank Cropanese, Neal Lafferty, Lena Zavyalova, Hoyoung Kang, Bruce Smith

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.537350

KEYWORDS: Prisms, Interferometers, Photoresist materials, Excimer lasers, Spatial coherence, Imaging systems, Optical lithography, Interferometry, Temporal coherence, Microfluidic imaging

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Proceedings Article | 28 May 2004 Paper

Approaching the numerical aperture of water immersion lithography at 193-nm

Bruce Smith, Anatoly Bourov, Yongfa Fan, Lena Zavyalova, Neal Lafferty, Frank Cropanese

Proceedings Volume 5377, (2004) https://doi.org/10.1117/12.537262

KEYWORDS: Water, Refractive index, Immersion lithography, Scattering, Prisms, Light scattering, Mie scattering, Interferometry, Absorption, Optical spheres

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SPIE Journal Paper | 1 January 2004

Water immersion optical lithography at 193 nm

Bruce Smith, Anatoly Bourov, Hoyoung Kang, Frank Cropanese, Yongfa Fan, Neal Lafferty, Lena Zavyalova

JM3, Vol. 3, Issue 01, (January 2004) https://doi.org/10.1117/12.10.1117/1.1637594

KEYWORDS: Water, Polarization, Optical lithography, Refractive index, Interferometry, Immersion lithography, Lithography, Photoresist materials, Microfluidics, Absorption

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Proceedings Article | 22 August 2001 Paper

Gauge control for sub-170-nm DRAM product features

Neal Lafferty, Christopher Gould, Michael Littau, Christopher Raymond

Proceedings Volume 4344, (2001) https://doi.org/10.1117/12.436754

KEYWORDS: Etching, Critical dimension metrology, Semiconducting wafers, Tolerancing, Lithography, Scatter measurement, Scanning electron microscopy, Metrology, Titanium, Diffraction

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