Approach to fabricating defect-free x-ray masks

Ikuo Okada; Takashi Ohkubo; Yasunao Saitoh; Misao Sekimoto; Tadahito Matsuda

doi:10.1117/12.209165

19 May 1995 Approach to fabricating defect-free x-ray masks

Ikuo Okada, Takashi Ohkubo, Yasunao Saitoh, Misao Sekimoto, Tadahito Matsuda

Proceedings Volume 2437, Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V; (1995) https://doi.org/10.1117/12.209165
Event: SPIE's 1995 Symposium on Microlithography, 1995, Santa Clara, CA, United States

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.

Citation Download Citation

Ikuo Okada, Takashi Ohkubo, Yasunao Saitoh, Misao Sekimoto, and Tadahito Matsuda "Approach to fabricating defect-free x-ray masks", Proc. SPIE 2437, Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V, (19 May 1995); https://doi.org/10.1117/12.209165

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