Dr. Xiaohai Li Profile

Dr. Xiaohai Li

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Publications (8)

Proceedings Article | 23 March 2020 Paper

Compact modeling to predict and correct stochastic hotspots in EUVL

Zachary Levinson, Yudhishthir Kandel, Yunqiang Zhang, Qiliang Yan, Makoto Miyagi, Xiaohai Li, Kevin Lucas

Proceedings Volume 11323, 1132324 (2020) https://doi.org/10.1117/12.2554099

KEYWORDS: Stochastic processes, Optical proximity correction, Extreme ultraviolet lithography, Data modeling, Critical dimension metrology, Calibration, Monte Carlo methods, Lithography, Failure analysis, Image processing

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Proceedings Article | 13 March 2012 Paper

Edge placement error reduction and ringing effect suppression using model based targeting techniques

Chris Cork, Xiaohai Li, Stephen Jang

Proceedings Volume 8326, 83261U (2012) https://doi.org/10.1117/12.916623

KEYWORDS: Optical proximity correction, Lithographic illumination, Photomasks, Lithography, Surface conduction electron emitter displays, Neodymium, Extreme ultraviolet lithography, Scanners, Image resolution, Optical lithography

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Proceedings Article | 23 March 2011 Paper

Tolerance-based OPC and solution to MRC-constrained OPC

Yang Ping, Xiaohai Li, Stephen Jang, Denny Kwa, Yunqiang Zhang, Robert Lugg

Proceedings Volume 7973, 79732M (2011) https://doi.org/10.1117/12.879947

KEYWORDS: Optical proximity correction, Tolerancing, Lithography, Image segmentation, Critical dimension metrology, Photomasks, Lithographic illumination, Detection and tracking algorithms, Laser induced breakdown spectroscopy, Roads

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Proceedings Article | 25 September 2010 Paper

Optical proximity correction challenges with highly elliptical contacts

Chris Cork, Levi Barnes, Yang Ping, Xiaohai Li, Stephen Jang

Proceedings Volume 7823, 78233R (2010) https://doi.org/10.1117/12.867247

KEYWORDS: Optical proximity correction, Photomasks, Calibration, Manufacturing, Semiconducting wafers, Tolerancing, Diffraction, Image processing, Critical dimension metrology, Immersion lithography

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The steady march of Moore's law demands ever smaller feature sizes to be printed and Optical Proximity Correction to correct to ever tighter dimensional tolerances. Recently pitch doubling techniques has relieved the pressure on CD reduction, which instead of being achieved lithographically are reduced by subsequent etching or chemical interaction with spin-on layers. CD tolerance reductions, however, still need to match the overall design rule shrinkage. The move to immersion lithography, where effective Numerical Apertures now reach 1.35, has been accompanied by a significantly reduction in depth of focus, especially on isolated contacts. To remedy this, RET techniques such as assist feature placement, have been implemented. Certain local placements of assist features and neighboring contacts are observed to result in highly elliptical contacts being printed. In some layouts small changes in the aspect ratio of the contact on the mask leads to strong changes in the aspect ratio of the printed contact, whereas in other layouts the response is very weak. This effect can be described as an aspect ratio MEEF. The latter type of contact can pose a significant challenge to the OPC recipe which is driven by the need to place the printed contour within a small range of distance from target points placed on the midpoint of edges of a nominally square contact. The OPC challenge naturally will be compounded when the target layout is rectangular in the opposite sense to the natural elliptical shape of the printed contact. Approaches to solving this can vary from intervening at the assist feature placement stage, at the possible loss of depth of focus, to accepting a certain degree of ellipticity in the final contour and making the OPC recipe concentrate on minimizing any residual errors. This paper investigates which contact layouts are most challenging, discusses the compromises associated with achieving the correction target and results are shown from a few different approaches to resolving these issues.

Proceedings Article | 4 March 2010 Paper

Improvement in process window aware OPC

Xiaohai Li, Yasushi Kojima, Hironobu Taoka, Akemi Moniwa, Matt St. John, Yang Ping, Randall Brown, Robert Lugg, Sooryong Lee

Proceedings Volume 7640, 76402O (2010) https://doi.org/10.1117/12.849904

KEYWORDS: Optical proximity correction, Lithography, Model-based design, Optical lithography, Process modeling, Roads, Lithographic illumination, Photomasks, Immersion lithography, Semiconductor manufacturing

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Proceedings Article | 11 May 2009 Paper

Double patterning addressing imaging challenges for near- and sub-k1=0.25 node layouts

Beom-Seok Seo, Dae-Kwon Kang, Myung-Soo Noh, Sung-Ho Lee, Christopher Cork, Gerald LukPat, Alexander Miloslavsky, Xiaohai Li, Kevin Lucas, Sooryong Lee

Proceedings Volume 7379, 73791N (2009) https://doi.org/10.1117/12.824300

KEYWORDS: Double patterning technology, Optical proximity correction, Silicon, Optical lithography, Photomasks, Logic, Etching, Manufacturing, Metals, Lithography

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A variety of innovations including the reduction of actinic wavelength, an increase in lens NA, an introduction of immersion process, and an aggressive OPC/RET technique have enabled device shrinkage down to the current 45nm node. The immaturity of EUV and high index immersion, have made logic manufacturers look at other ways of leveraging existing exposure technologies as they strive to develop process technology for 32nm and below. For design rules for sub-nodes from 32nm to 22nm, the need to define critical layers with double photolithography and etch process becomes increasingly evident. Double patterning can come in a variety of forms or 'flavors'. For 32/28nm node, the patterning of 2D features is so challenging that opposing line-ends can only be defined using an additional litho and etch step to cut them. For 22nm node, even line/space gratings are below the theoretical k1=0.25 imaging limit. Therefore pitch-doubling double patterning decomposition is absolutely required. Each double patterning technology has its own set of challenges. Most of all, an existing design often cannot be shrunk blindly and then successfully decomposed, so an additional set of restrictions is required to make layouts double patterning compliant. To decompose a logic layout into two masks, polygons often need to be cut so that they can be patterned using both masks. The electric performance of this cut circuitry may be highly dependent on the quality of layout decomposition, the circuit characteristics and its sensitivity to misalignment between the two patterning steps. We used representative logic layouts of metal level and realistic models to demonstrate the issues involved and attempt to define formal rules to help enable lineend splitting and pitch-doubling double patterning decomposition. This study used a variety of shrink approaches to existing legacy layouts to evaluate double patterning compliance and a careful set-up of parameters for the pitch splitting decomposition engine. The quality of the resultant imaging was tuned using double patterning aware OPC and printability verification tools.

Proceedings Article | 16 March 2009 Paper

Double-patterning-friendly OPC

Xiaohai Li, Gerry Luk-Pat, Chris Cork, Levi Barnes, Kevin Lucas

Proceedings Volume 7274, 727414 (2009) https://doi.org/10.1117/12.815175

KEYWORDS: Optical proximity correction, Photomasks, Etching, Optical lithography, Double patterning technology, Semiconducting wafers, Critical dimension metrology, Model-based design, Printing, Resolution enhancement technologies

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Proceedings Article | 19 May 2008 Paper

AF fixer: new incremental OPC method for optimizing assist feature

Sung-Gon Jung, Sang-Wook Kim, Sung-Soo Suh, Young-Chang Kim, Suk-Joo Lee, Sung-Woon Choi, Woo-Sung Han, Joo-Tae Moon, Levi Barnes, Xiaohai Li, Robert Lugg, Sooryong Lee, Kyoil Koo, Munhoe Do, Frank Amoroso, Benjamin Painter

Proceedings Volume 7028, 70280Y (2008) https://doi.org/10.1117/12.793040

KEYWORDS: Atrial fibrillation, Optical proximity correction, Printing, Photomasks, Manufacturing, Scanners, Image segmentation, Process modeling, Optical lithography, Data modeling

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Showing 5 of 8 publications

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