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Proceedings Paper

Challenge toward breakage of RLS trade-off for EUV lithography by Photosensitized Chemically Amplified Resist (PSCAR) with flood exposure
Author(s): Seiji Nagahara; Michael Carcasi; Hisashi Nakagawa; Elizabeth Buitrago; Oktay Yildirim; Gosuke Shiraishi; Yuichi Terashita; Yukie Minekawa; Kosuke Yoshihara; Masaru Tomono; Hironori Mizoguchi; Joel Estrella; Tomoki Nagai; Takehiko Naruoka; Satoshi Dei; Masafumi Hori; Akihiro Oshima; Michaela Vockenhuber; Yasin Ekinci; Marieke Meeuwissen; Coen Verspaget; Rik Hoefnagels; Gijsbert Rispens; Raymond Maas; Hideo Nakashima; Seiichi Tagawa
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Paper Abstract

This paper proposes a promising approach to break the resolution (R), line-edge-roughness (LER), and sensitivity (S) trade-off (RLS trade-off) relationships that limit the ultimate lithographic performance of standard chemically amplified resists (CAR). This is accomplished in a process that uses a Photosensitized Chemically Amplified Resist (PSCAR) in combination with a flood-exposure in an in-line track connected to a pattern exposure tool. PSCAR is a modified CAR which contains a photosensitizer precursor (PP) in addition to other standard CAR components such as a protected polymer, a photo acid generator (PAG) and a quencher. In this paper, the PSCAR concept and the required conditions in resist formulation are carefully explained. In the PSCAR process, the sensitivity improvement is accomplished by PAG decomposition to selectively generate more acid at the pattern exposed areas during the flood exposure. The selective photosensitization happens through the excitation of the photosensitizer (PS) generated by the deprotection of the PP at the pattern exposed areas. A higher resist chemical gradient which leads to an improved resolution and lower LER values is also predicted using the PSCAR simulator. In the PSCAR process, the improved chemical gradient can be realized by dual acid quenching steps with the help of increased quencher concentration. Acid quenching first happens simultaneously with acid catalytic PP to PS reactions. As a result, a sharpened PS latent image is created in the PSCAR. This image is subsequently excited by the flood exposure creating additional acid products at the pattern exposed areas only. Much the same as in the standard CAR system, unnecessary acid present in the non-pattern exposed areas can be neutralized by the remaining quencher to therefore produce sharper acid latent images. EUV exposure results down to 15 nm half pitch (HP) line/space (L/S) patterns using a PSCAR resist indicate that the use of PSCAR has the potential to improve the sensitivity of the system while simultaneously improving the line-width-roughness (LWR) with added quencher and flood exposure doses. In addition, improved across-wafer critical dimension uniformity (CDU) is realized by the use of a PSCAR in combination with a flood exposure using pre α UV exposure module.

Paper Details

Date Published: 22 March 2016
PDF: 18 pages
Proc. SPIE 9776, Extreme Ultraviolet (EUV) Lithography VII, 977607 (22 March 2016); doi: 10.1117/12.2219433
Show Author Affiliations
Seiji Nagahara, Tokyo Electron Ltd. (Japan)
Michael Carcasi, Tokyo Electron America, Inc. (United States)
Hisashi Nakagawa, JSR Corp. (Japan)
Elizabeth Buitrago, Paul Scherrer Institute (Switzerland)
Oktay Yildirim, ASML Netherlands B.V. (Netherlands)
Gosuke Shiraishi, Tokyo Electron Kyushu Ltd. (Japan)
Yuichi Terashita, Tokyo Electron Kyushu Ltd. (Japan)
Yukie Minekawa, Tokyo Electron Kyushu Ltd. (Japan)
Kosuke Yoshihara, Tokyo Electron Kyushu Ltd. (Japan)
Masaru Tomono, Tokyo Electron Kyushu Ltd. (Japan)
Hironori Mizoguchi, Tokyo Electron Kyushu Ltd. (Japan)
Joel Estrella, Tokyo Electron America, Inc. (United States)
Tomoki Nagai, JSR Corp. (Japan)
Takehiko Naruoka, JSR Corp. (Japan)
Satoshi Dei, JSR Micro N.V. (Belgium)
Masafumi Hori, JSR Micro N.V. (Belgium)
Akihiro Oshima, Osaka Univ. (Japan)
Michaela Vockenhuber, Paul Scherrer Institute (Switzerland)
Yasin Ekinci, Paul Scherrer Institute (Switzerland)
Marieke Meeuwissen, ASML Netherlands B.V. (Netherlands)
Coen Verspaget, ASML Netherlands B.V. (Netherlands)
Rik Hoefnagels, ASML Netherlands B.V. (Netherlands)
Gijsbert Rispens, ASML Netherlands B.V. (Netherlands)
Raymond Maas, ASML Netherlands B.V. (Netherlands)
Hideo Nakashima, Tokyo Electron Ltd. (Japan)
Seiichi Tagawa, Osaka Univ. (Japan)


Published in SPIE Proceedings Vol. 9776:
Extreme Ultraviolet (EUV) Lithography VII
Eric M. Panning, Editor(s)

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