Dr. Rongkuo Zhao Profile

Dr. Rongkuo Zhao

Postdoc Research Fellow

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Publications (8)

Proceedings Article | 28 April 2023 Paper

Computational lithography solutions to support EUV high-NA patterning

Rongkuo Zhao, Fan Zhou, Jialei Tang, Jeff Lu, Yunbo Liu, Dezheng Sun, Ming-Chun Tien, Stephen Hsu, Rachit Gupta, Youping Zhang, Joerg Zimmermann

Proceedings Volume 12495, 124950R (2023) https://doi.org/10.1117/12.2660858

KEYWORDS: Source mask optimization, SRAF, Light sources and illumination, Extreme ultraviolet, 3D mask effects, Image quality, Computational lithography

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Proceedings Article | 28 April 2023 Presentation + Paper

Overview of stitching for high NA: imaging and overlay experimental and simulation results

Natalia Davydova, Lieve van Look, Vincent Wiaux, Joost Bekaert, Frank Timmermans, Eelco van Setten, Bram Slachter, Laura Huddleston, Claire van Lare, Rongkuo Zhao, Dezheng Sun, Ming-Chun Tien, Marcel Beckers, Simon van Gorp, Cees Lambregts, Chung-Tien Li, Arthur van de Nes, Koen D'Havé, Tatiana Kovalevich, Diederik de Bruin, Stephen Hsu, Rene Carpaij

Proceedings Volume 12494, 124940Q (2023) https://doi.org/10.1117/12.2658511

KEYWORDS: Photomasks, Optical proximity correction, Reflection, Critical dimension metrology, Tantalum, Reflectivity, Metrology, Semiconducting wafers, Scanners, Reticles

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Proceedings Article | 31 October 2022 Poster

Stitching for High NA: new insights and path forward

Natalia Davydova, Vincent Wiaux, Joost Bekaert, Frank Timmermans, Bram Slachter, Tatiana Kovalevich, Eelco van Setten, Marcel Beckers, Simon van Gorp, Rongkuo Zhao, Dezheng Sun, Ming-Chun Tien, Hoon Ser, Diederik de Bruin, Stephen Hsu, Rene Carpaij

Proceedings Volume PC12292, PC1229210 (2022) https://doi.org/10.1117/12.2653388

KEYWORDS: Tantalum, Image resolution, Source mask optimization, Scanners, Reflectivity, Optical proximity correction, Manufacturing, Extreme ultraviolet lithography, Control systems

Proceedings Article | 3 October 2022 Presentation

Optical magnetic trapping of nanoparticles

Sui Yang, Xuexin Ren, Rongkuo Zhao, Bo Wang, Haokun Li, Yuan Wang, Lei Shi, Xiang Zhang

Proceedings Volume PC12198, PC1219819 (2022) https://doi.org/10.1117/12.2640648

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Proceedings Article | 13 June 2022 Presentation

KrF Multi-focal imaging system for advanced and legacy applications

Will Conley, G. Padmabandu, Yzzer Roman, Yingbo Zhao, Toufiq Aman, James Bonafede, Emmanuel Rausa, Rasmus Nielsen, Ijen van Mil, Rongkuo Zhao

Proceedings Volume PC12051, PC120510B (2022) https://doi.org/10.1117/12.2615263

KEYWORDS: Imaging systems, Process control, Photoresist materials, Lithography, 3D image processing, Semiconducting wafers, Scanners, Overlay metrology, Optical lithography, Image processing

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Proceedings Article | 26 May 2022 Presentation + Paper

A novel solution on KrF pixel layer with thick photo resist (PR) by single exposure multi-focal imaging (SE MFI) technique

Zhenhai Yao, Lequn Jin, Yuhua Li, Maoqun Jiang, Fabin Huang, Min Fang, Xichen Sheng, Rongkuo Zhao, Michael Crouse, Chris Kaplan, Dongqing Zhang, Dongxiang Shi, Zhonghua Xu, Chaoqun Guo, Pieter Scheijgrond, Xiaoyang Jason Li, Stephen Hsu, Will Conley, Zhen Tang

Proceedings Volume 12051, 1205109 (2022) https://doi.org/10.1117/12.2616830

KEYWORDS: Semiconducting wafers, Chromatic aberrations, Data modeling, Calibration, Source mask optimization, Photomasks, SRAF, Copper indium disulfide, Optical lithography, Image processing

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Advancing technology nodes in CMOS Image Sensors (CIS) continues to drive a shrinking process to acquire higher resolution and low power consumption as well as more cost-effective production. With the sensor pixel size scaling down, a thicker photoresist (with aspect ratios greater than 10:1) is introduced to block high-energy implants with extremely localized implant profiles. Then double exposures/double focus (DE/DF) is applied to make sure the resist profile and process window is comparable or better. However, this process is a big challenge at high volume manufacturing (HVM) phase because of throughput loss. To recover it due to DE/DF, we invented SE MFI which uses two wavelengths (“colors”) generated by the KrF excimer laser to solve the problem. Due to the chromatic aberrations in the lens, the focal plane shift of different wavelength produces nearly the same result as DE/DF. However, the use of two-wavelengths brings some challenges. The first is the loss of image contrast and the second is the impact of chromatic aberrations across the slit which results in image shift and image asymmetry. In this work, we demonstrated that the use of ASML’s Tachyon KrF MFI source mask optimization (SMO) that can match the MFI SE process to DE/DF process of record (POR). We first used Tachyon Focus-Exposure Modeling plus (FEM+) to calibrate a DE resist model by using DE POR wafer data. Then we converted the DE model to a SE MFI model. At the end, we use the Tachyon MFI-SMO to optimize the SE MFI to match the DE/DF and MFI sidewall profiles through process window conditions at the center slit. We achieved making the MFI and DE/DF sidewall difference significantly smaller than other noises which can be measured on wafer at the center slit. We evaluated the chromatic aberration impact on through slit sidewall profiles also meet the specification. The through slit matching between MFI and DE/DF was further improved by through-slit mask optimization. This is done by inserting asymmetry sub resolution assist features (SRAFs). Tachyon Optical Proximity Correction plus (OPC+) can support full chip mask corrections for full-chip HVM. The above MFI technology including Tachyon optimization capability will be verified by wafer exposure via comparison between MFI and DE wafer results.

Proceedings Article | 26 February 2021 Presentation

Full chip computational lithography for KrF multi-focal imaging (MFI) (Conference Presentation)

Will Conley, Vince Vince Plachecki, Stephen Hsu, Michael Crouse, Rongkuo Zhao, John He, Pieter Scheijgrond, Dezheng Sun, Xiaoyang Li, Dongqing Zhang, Ming-Chun Tien, Jun Ye, Rafael Howell, Chen Liu, Xiaolong Zhang, Hai Li, Zuanyi Li, Xiaobo Xie, Jing Su, Yzzer Roman

Proceedings Volume 11613, 116130E (2021) https://doi.org/10.1117/12.2585651

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Proceedings Article | 11 September 2010 Paper

Chiral metamaterials reduce the attractive Casimir force

R. Zhao, Th. Koschny, E. Economou, C. Soukoulis

Proceedings Volume 7754, 77540Z (2010) https://doi.org/10.1117/12.862555

KEYWORDS: Chiral metamaterials, Magnetism, Resonators, Silver, Terahertz radiation, Physics, Dielectrics, Picosecond phenomena, Circuit switching, Reflection

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Showing 5 of 8 publications

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