Damage control during dry etching of EUV mask: I. Control of surface roughness

Eiichi Hoshino; Taro Ogawa; Masashi Takahashi; Hiromasa Hoko; Hiromasa Yamanashi; Naoya Hirano; Shinji Okazaki

doi:10.1117/12.373372

30 December 1999 Damage control during dry etching of EUV mask: I. Control of surface roughness

Eiichi Hoshino, Taro Ogawa, Masashi Takahashi, Hiromasa Hoko, Hiromasa Yamanashi, Naoya Hirano, Shinji Okazaki

Proceedings Volume 3873, 19th Annual Symposium on Photomask Technology; (1999) https://doi.org/10.1117/12.373372
Event: Photomask Technology and Management, 1999, Monterey, CA, United States

Abstract

To obtain good optical properties in an EUVL mask, the substrate should not suffer any damage either during mask fabrication or during use. As one step in ensuring that this is the case, the surface roughness of patterns etched on a mask substrate was examined, since it reduces the reflectance of the substrate. The experiments involved coating a Mo/Si multilayer with a SiO₂ buffer layer and a Ta absorber layer. After the absorber was dry etched with a mixture of Cl₂ and BCl₃ gases, dry etching was used to over-etch the buffer layer. It was found that dry etching with Cl₂ + BCl₃ provides both a smooth Ta surface (roughness: less than 1 nm rms) and good control of the etching depth, even though the Ta etching rate was very high (389.6 nm/min.). The results indicate that the process used in this study is quite suitable for making absorber patterns.

Citation Download Citation

Eiichi Hoshino, Taro Ogawa, Masashi Takahashi, Hiromasa Hoko, Hiromasa Yamanashi, Naoya Hirano, and Shinji Okazaki "Damage control during dry etching of EUV mask: I. Control of surface roughness", Proc. SPIE 3873, 19th Annual Symposium on Photomask Technology, (30 December 1999); https://doi.org/10.1117/12.373372

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