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Proceedings Paper

Capability of DUV inspection for the LWR improved EUV mask of sub-15 nm hp on wafer
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Paper Abstract

Deep Ultra Violet (DUV) inspection of Extreme Ultra Violet (EUV) mask has been known for high stability, high throughput, and low cost, since it has been used for a long time, even though sensitivity is thought to be insufficient for the EUV mask of under 20 nm half pitch (hp). We have been studying extendibility for 1X nm hp of the DUV inspection using optics named Super Inspection Resolution Improvement method for UnreSolved pattern (SIRIUS). In previous study, we demonstrated the DUV inspection has capability for the EUV mask of 17 nm hp Lines and Spaces (LS) on wafer. In this paper, the more extendibility for the DUV inspection of EUV masks under sub-15 nm on wafer was demonstrated by studying relationship of roughness and sensitivity. Firstly, an estimated model for effects of the EUV mask roughness to Signal Noise Ratio (SNR) of the inspection image was established, and simulation was carried out. Secondly, the SNR was evaluated using actual Line Width Roughness (LWR) improved masks. It was confirmed that the results are the same trend as the model and the simulation, and, the SNR is enhanced with the LWR improvement. Finally, the sensitivity of the LWR improved mask was evaluated. As a result, it becomes enough for the EUV mask over 13 nm hp on wafer. In conclusion, we confirm that the DUV inspection of the EUV mask by the SIRIUS can be extending to the 13 nm hp LS on wafer, this is around the limit of NA 0.33 EUV lithography, using the LWR improved mask.

Paper Details

Date Published: 29 September 2019
PDF: 18 pages
Proc. SPIE 11148, Photomask Technology 2019, 111480X (29 September 2019); doi: 10.1117/12.2536474
Show Author Affiliations
Masato Naka, Toshiba Memory Corp. (Japan)
Keisuke Chiba, Toshiba Memory Corp. (Japan)
Ai Kumada, Toshiba Memory Corp. (Japan)
Keiko Morishita, Toshiba Memory Corp. (Japan)
Kosuke Takai, Toshiba Memory Corp. (Japan)
Ryoji Yoshikawa, Toshiba Memory Corp. (Japan)
Yukiyasu Arisawa, Toshiba Memory Corp. (Japan)
Takashi Kamo, Toshiba Memory Corp. (Japan)
Eishi Shiobara, Toshiba Memory Corp. (Japan)
Shingo Kanamitsu, Toshiba Memory Corp. (Japan)

Published in SPIE Proceedings Vol. 11148:
Photomask Technology 2019
Jed H. Rankin; Moshe E. Preil, Editor(s)

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