We developed the novel process and material which can prevent the pattern collapse issue perfectly. The process was Dry Development Rinse (DDR) process, and the material used in this process was DDR material. DDR material was containing siloxane polymer which could be replaced the space area of the photo resist pattern. And finally, the reversed pattern would be created by dry etching process without any pattern collapse issue.
This novel process was useful not only in positive tone development (PTD) process but also in negative tone development (NTD) process. We newly developed DDR material for NTD process. Novel DDR material for NTD consists of special polymer and it used organic solvent system. New DDR materials showed no mixing property for NTD PR, so fine pattern of NTD PR could be filled by DDR materials then tone reverse could be achieved by dry etching process.
Tone reverse was successfully achieved by combination of NTD PR and DDR process keeping good pattern quality in EUV lithography. Reversed pattern below hp 14nm was obtained without any pattern collapse issue, which couldn’t be created by just using normal NTD process.
Reversed contact hole could be obtained in NTD-DDR process at 24nm hole size. Reversed C/H made by NTD pillar showed good LCDU compared to PTD C/H. In addition, reversed C/H at 20nm hole size could be achieved in NTD-DDR process.
In DDR process, enough etch back is important to obtained fine reversed pattern with lower roughness but long etch back time caused degradation of the reversed pattern. Then etch back time was evaluated with NTD PR and DDR material. Reversed C/H showed minimum LCDU when short etch back time was applied, however degradation of LCDU was observed when long etch back was applied. LCDU of reversed C/H made by NTD-DDR process was 3.2nm. On the other hands, LCDU of normal C/H made by PTD process was 3.5nm, so reversed C/H from NTD pillar showed better LCDU than PTD C/H when suitable etch back was applied.
Shuhei Shigaki, Satoshi Takeda, Wataru Shibayama, Makoto Nakajima, and Rikimaru Sakamoto, "DDR process and materials for NTD photo resist in EUV lithography," Proc. SPIE 10450, International Conference on Extreme Ultraviolet Lithography 2017, 104500N (Presented at SPIE Photomask Technology and EUV Lithography: September 13, 2017; Published: 16 October 2017); https://doi.org/10.1117/12.2280536.
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