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Proceedings Paper

A simple method of source optimization for advanced NAND FLASH process
Author(s): Yi-Shiang Chang; Satoshi Ogasawara; Koichi Fujii; Shigeru Hirukawa; Motokatsu Imai; Wan-Lin Kuo; Chia-Chi Lin
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Paper Abstract

We have developed a very simple source optimization (SO) method for L/S and C/H critical layers patterning of advanced NAND FLASH. Starting from the strong off-axis illumination shape which is optimized for the finest structure of the mask pattern, a systematic procedure is performed to extract the optimum parameters of additional assist sources to balance the imaging performance (DOF, contrast and optical proximity effect, etc.) of dense/sparse/rough patterns. Performance equations (linear optimization) with performance map (sensitivity) are utilized to search the best combination of intensity for each assist source. For C/H pattern, the optimization procedure is modified to solve the non-linearity and non-continuity problems on the relationship between assist source intensity and each imaging performance. Finally, optimized source shapes have been successfully demonstrated and verified on 40 nm node NAND FLASH L/S and C/H critical patterns despite the simplicity of the optimization method, without utilizing SO dedicated software.

Paper Details

Date Published: 22 March 2011
PDF: 12 pages
Proc. SPIE 7973, Optical Microlithography XXIV, 79731Z (22 March 2011); doi: 10.1117/12.878887
Show Author Affiliations
Yi-Shiang Chang, Powerchip Technology Corp. (Taiwan)
Satoshi Ogasawara, Nikon Corp. (Japan)
Koichi Fujii, Nikon Corp. (Japan)
Shigeru Hirukawa, Nikon Corp. (Japan)
Motokatsu Imai, Nikon Corp. (Japan)
Wan-Lin Kuo, Powerchip Technology Corp. (Taiwan)
Chia-Chi Lin, Powerchip Technology Corp. (Taiwan)

Published in SPIE Proceedings Vol. 7973:
Optical Microlithography XXIV
Mircea V. Dusa, Editor(s)

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