Mr. Xiang Liu Profile

Xiang Liu

at Tokyo Electron Ltd

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Author

Publications (5)

Proceedings Article | 9 April 2024 Presentation + Paper

Advanced processes in metal-oxide resists for high-NA EUV lithography

Cong Que Dinh, Seiji Nagahara, Kayoko Cho, Hikari Tomori, Yuhei Kuwahara, Tomoya Onitsuka, Soichiro Okada, Shinichiro Kawakami, Arisa Hara, Seiji Fujimoto, Makoto Muramatsu, Reiko Tsuzuki, Xiang Liu, Arame Thiam, Yannick Feurprier, Kathleen Nafus, Michael Carcasi, Lior Huli, Kanzo Kato, Alexandra Krawicz, Michael Kocsis, Peter De Schepper, Lauren McQuade, Kazuki Kasahara, Jara Garcia Santaclara, Rik Hoefnagels, Bruno La Fontaine, Ryan Miyakawa, Chris Anderson, Patrick Naulleau

Proceedings Volume 12957, 1295705 (2024) https://doi.org/10.1117/12.3010207

KEYWORDS: Extreme ultraviolet lithography, Extreme ultraviolet, Inspection, Tin, Lithography, Etching

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One of the key steps in the pattern formation chain of extreme ultraviolet (EUV) lithography is the development process to resolve the resist pattern after EUV exposure. The traditional development process might be insufficient to achieve the requirements of ultra-high-resolution features with low defect levels. The aim of this paper is to establish a process to achieve a good roughness, a low defectivity at a low EUV dose, and capability for extremely-high-resolution for high numerical aperture (NA) and hyper-NA EUV lithography. A new development method named ESPERT™ (Enhanced Sensitivity develoPER Technology™) has been introduced to improve the performance of metal oxide-resists (MOR). ESPERT™ as a chemical super resolution technique effectively apodized the MOR chemical image, improving chemical gradient (higher exposure latitude (EL)) and reducing scums (fewer bridge defects). This new development method can also keep the resist profile vertical to mitigate the break defects. The performances of the conventional development and ESPERT™ were evaluated and compared using 0.33 NA EUV, 0.5 NA EUV, and electron beam (EB) exposures, for all line-space (LS), contact hole (CH), and pillar (PL) patterns. Using 0.33 NA EUV scanners on LS patterns, both bridge and break defects were confirmed to be reduced for all 32-nm-pitch, 28-nm-pitch, 26-nm-pitch LS patterns while reducing the EUV dose to size (DtS). In the electrical yield (1 meter length) test of breaks/bridges of 26-nm pitch structures, ESPERT™ reduced EUV dose while its combo yield was almost 100% over a wide dose range of 20mJ/cm². For CH patterns, in the case of 32-nm-pitch AEI (after etch inspection), EL was increased 7.5% up to 22.5%, while failure free latitude (FFL) was widened from 1-nm to 4-nm. A 16-nm-pitch LS pattern was successfully printed with 0.5 NA tool, while a 16-nm-pitch PL and an 18-nm-pitch CH patterns were also achieved with an EB lithography by ESPERT™. With ESPERT™, there was no pillar collapse observed for 12-nm half-pitch PL by 0.5 NA and 8-nm half-pitch PL by EB. With all the advantages of having a high exposure sensitivity, a low defectivity, and an extremely-high-resolution capability, this advanced development method is expected be a solution for high-NA EUV towards hyper-NA EUV lithography.

Proceedings Article | 1 May 2023 Paper

Advanced development methods for high-NA EUV lithography

Cong Que Dinh, Seiji Nagahara, Yuhei Kuwahara, Arnaud Dauendorffer, Soichiro Okada, Seiji Fujimoto, Shinichiro Kawakami, Satoru Shimura, Makoto Muramatsu, Kayoko Cho, Xiang Liu, Kathleen Nafus, Michael Carcasi, Ankur Agarwal, Mark Somervell, Lior Huli, Kanzo Kato, Michael Kocsis, Peter De Schepper, Stephen Meyers, Lauren McQuade, Kazuki Kasahara, Jara Garcia Santaclara, Rik Hoefnagels, Chris Anderson, Patrick Naulleau

Proceedings Volume 12498, 1249806 (2023) https://doi.org/10.1117/12.2655928

KEYWORDS: Extreme ultraviolet lithography, Extreme ultraviolet, Line width roughness, Line edge roughness, Lithography, Etching

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One of the key steps in the pattern formation chain of (extreme ultraviolet) EUV lithography is the development process to resolve the resist pattern after EUV exposure. A simple traditional development process might not be sufficient to achieve the requirements of an ultra-high-resolution feature with low defect levels in high numerical aperture (NA) EUV lithography. In our previous literature, a new development method named ESPERT^TM (Enhanced Sensitivity develoPER Technology^TM) has been introduced to improve the performance of metal oxide resists (MOR) for 0.33 NA EUV lithography by breaking the dose-roughness trade-off. In this work, this development technique was optimised for high-NA lithography to not only keep the advantages of previous ESPERT^TM version, but also reduce the defect levels at a higher EUV sensitivity. This is made possible thanks to the capability of the new version of ESPERT^TM that can easily remove the residue (undeveloped resist) at low exposure dose area to enhance the developing contrast. Using 0.33 NA EUV scanners at imec on 16-nm half-pitch (HP) line/space (L/S) patterns, with the new development method, EUV dose-to-size (DtS) was reduced roughly 16%, and total after-development-inspection (ADI) defects was reduced by a factor of approximately 7, simultaneously. In another condition, DtS was reduced from 44.2 to 28.4 mJ/cm² (an improvement of 36%), while the number of after-etch-inspection (AEI) single-bridge defects was reduced by half, simultaneously. Using the 0.5 NA exposure tool at Lawrence Berkeley National Laboratory with this new development method, the exposure sensitivity and line-width-roughness (LWR) were both improved by 30% and 21%, respectively. An 8-nm-HP L/S pattern was also successfully printed by this high NA tool. Using a 150 kV electron-beam (EB) lithography system, a 12-nm-HP of pillars was successfully printed on a 22-nm-thick MOR resist with ESPERT^TM. With all the advantages of having a high exposure sensitivity, a low defectivity, and an ultra-high-resolution capability, this new development method is expected to be a solution for high-NA EUV lithography.

Proceedings Article | 1 May 2023 Poster + Paper

Recent advances in EUV patterning in preparation towards high-NA EUV

Seiji Nagahara, Arnaud Dauendorffer, Arame Thiam, Xiang Liu, Yuhei Kuwahara, Cong Que Dinh, Soichiro Okada, Shinichiro Kawakami, Hisashi Genjima, Noriaki Nagamine, Makoto Muramatsu, Satoru Shimura, Atsushi Tsuboi, Kathleen Nafus, Yannick Feurprier, Marc Demand, Rajesh Ramaneti, Philippe Foubert, Danilo De Simone, Geert Vendenberghe

Proceedings Volume 12498, 124981G (2023) https://doi.org/10.1117/12.2657432

KEYWORDS: Optical lithography, Extreme ultraviolet, Extreme ultraviolet lithography, Interfaces, Etching, Coating thickness, Lithography, Stochastic processes, Critical dimension metrology

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Proceedings Article | 11 November 2022 Presentation

Holistic litho-etch development to address patterning challenges towards high NA EUV

Seiji Nagahara, Arnaud Dauendorffer, Xiang Liu, Tomoya Onitsuka, Hisashi Genjima, Noriaki Nagamine, Yuhei Kuwahara, Yuya Kamei, Shinichiro Kawakami, Makoto Muramatsu, Satoru Shimura, Kathleen Nafus, Noriaki Oikawa, Yannick Feurprier, Marc Demand, Sophie Thibaut, Alexandra Krawicz, Steven Grzeskowiak, Katie Lutker-Lee, Eric Liu, Christopher Catano, Joshua LaRose, Jeffrey Shearer, Lior Huli, Philippe Foubert, Danilo De Simone

Proceedings Volume PC12292, PC122920N (2022) https://doi.org/10.1117/12.2642941

KEYWORDS: Extreme ultraviolet, Optical lithography, Extreme ultraviolet lithography, Etching, Plasma etching, Lithography, Yield improvement, Stochastic processes, Plasma, Photoresist materials

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Proceedings Article | 26 May 2022 Presentation + Paper

High NA EUV stochastic resist modeling considered with development parameters

R. Tsuzuki, X. Liu, K. Oyama

Proceedings Volume 12051, 120510F (2022) https://doi.org/10.1117/12.2613438

KEYWORDS: Calibration, Extreme ultraviolet, Photoresist processing, Extreme ultraviolet lithography, Data modeling, Stochastic processes, Floods, Electroluminescence, Ultraviolet radiation, Oxides

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