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Proceedings Paper

Analysis of x-ray mask distortion
Author(s): Yuusuke Tanaka; Takuya Yoshihara; Shinji Tsuboi; Kiyoshi Fujii; Katsumi Suzuki
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Paper Abstract

We measured the x-ray mask distortion induced in the back- etching step in wafer processing and evaluated the contributions of SiN or SiC membrane stress and its uniformity along with Ta absorber stress and its uniformity to the distortion. Membrane stress nonuniformity causes a large amount of distortion in SiC membrane masks while it causes a small amount in SiN membrane masks. Absorber stress nonuniformity causes a large amount of distortion in Ta/SiN membrane masks, but it is expected to be reduced by 60% in Ta/SiC membrane masks. In wafer processing, therefore, the main cause of the distortion in Ta/SiN membrane masks is SiN membrane stress and absorber stress nonuniformity while in Ta/SiC membrane masks it is SiC membrane stress and its nonuniformity. We used these distortion component data to estimate the distortion induced in membrane processing. The distortion caused by SiN or SiC membrane stress is expected to be zero and the distortion caused by SiN or SiC membrane stress nonuniformity is expected to be less than 10 nm in membrane processing. As a result, for a pattern density of 50%, adopting membrane processing would reduce process-induced distortion by 50% in Ta/SiN membrane masks and by 75% in Ta/SiC membrane masks. The combination of SiC membranes and membrane processing significantly reduces process-induced distortion.

Paper Details

Date Published: 28 July 1997
PDF: 9 pages
Proc. SPIE 3096, Photomask and X-Ray Mask Technology IV, (28 July 1997); doi: 10.1117/12.277274
Show Author Affiliations
Yuusuke Tanaka, NEC Corp. (Japan)
Takuya Yoshihara, NEC Corp. (Japan)
Shinji Tsuboi, NEC Corp. (Japan)
Kiyoshi Fujii, NEC Corp. (Japan)
Katsumi Suzuki, NEC Corp. (Japan)


Published in SPIE Proceedings Vol. 3096:
Photomask and X-Ray Mask Technology IV
Naoaki Aizaki, Editor(s)

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