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22 January 2001 Dry etching of Ta absorber for EUVL masks
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To obtain a vertical profile for the Ta absorber pattern of an EUVL (Extreme Ultraviolet Lithography) mask, the dry etching conditions were reconsidered. The experiments employed ECR (electron cyclotron resonance) plasma etching and Si wafers coated with a 40-nm-thick SiO2 buffer layer and a 100-nm-thick Ta absorber layer. Two-step etching was performed to obtain vertical pattern profiles. In the first step, the surface region of the Ta absorber was etched with a mixture of BCl3 and Cl2 gases to reduce the residue from the native oxide film. Then, the absorber was etched with Cl2 gas at a higher RF (radio frequency) bias power to obtain a vertical profile and smooth sidewalls. Furthermore, the thermal behavior of a standard 6- inch-square 250-mil. substrate was also simulated. It was found that the temperature rise of the substrate could be kept under 150 deg. Celsius.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Eiichi Hoshino, Taro Ogawa, Naoya Hirano, Hiromasa Hoko, Masashi Takahashi, Hiromasa Yamanashi, Akira Chiba, Masaaki Ito, and Shinji Okazaki "Dry etching of Ta absorber for EUVL masks", Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001);

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