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Proceedings Paper

Approach to fabricating defect-free x-ray masks
Author(s): Ikuo Okada; Takashi Ohkubo; Yasunao Saitoh; Misao Sekimoto; Tadahito Matsuda
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Paper Abstract

A Ta absorber x-ray mask fabrication process has been developed that virtually eliminates mask defects. Since most mask defects originate in 2 micrometers thick SiN deposits, the surfaces of the deposited SiN films are polished to make them as smooth as possible. To eliminate the contamination that occurs in fabrication processes, such as back-etching of the substrate, a wet-cleaning technique is employed that uses a strong acid like H2SO4 + H2O2. By using these polishing and cleaning techniques, the defect density can be reduced to less that 5 defects/cm2. To carry out x-ray mask inspection by an electron-beam x-ray mask inspection system, die-to-die comparison of printed resist patterns is introduced. A focused ion beam x-ray mask repair system is used to repair mask defects. Clear repairs are made with Ta deposited on a Ta absorber. The repaired Ta absorber patterns have high chemical durability and are not damaged by strong acid wet- cleaning. This mask fabrication process has led to the production of virtually defect-free x-ray masks with a reasonable yield.

Paper Details

Date Published: 19 May 1995
PDF: 11 pages
Proc. SPIE 2437, Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V, (19 May 1995); doi: 10.1117/12.209165
Show Author Affiliations
Ikuo Okada, NTT LSI Labs. (Japan)
Takashi Ohkubo, NTT Advanced Technology Corp. (Japan)
Yasunao Saitoh, NTT LSI Labs. (Japan)
Misao Sekimoto, NTT LSI Labs. (Japan)
Tadahito Matsuda, NTT LSI Labs. (Japan)

Published in SPIE Proceedings Vol. 2437:
Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V
John M. Warlaumont, Editor(s)

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