25 March 2016 Challenges for immersion lithography extension based on negative tone imaging (NTI) process
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Negative tone imaging (NTI) process is a method for obtaining a negative-tone reversal pattern by developing with an organic solvent. As NTI process can break-through the resolution limit of a conventional positive tone development (PTD) process at specific pattern such as trenches and contact holes, it have been applied for a mass production in 20nm and 14nm nodes devices. In NTI system, because a developer is changed from a hydrophilic aqueous solution to a hydrophobic organic solvent, it is possible to review the common resist stack which is optimized for a PTD process. In this paper, we examined the possibility of a bi-layer process using a Si-containing NTI resist. Etching selectivity between the Si-NTI resist and a SOC improved by raising Si-content of the Si-NTI resist, but resolution deteriorates as a trade-off. By suppressing swelling behavior of the Si-NTI resist with a polymer structure control, we overcame this trade-off. As a result, in sub-90 nm pitch L/S and CH patterns, the resolution of the Si-NTI resist achieved comparable level to a conventional NTI resist. In addition, SOC etching was successfully carried out by using the Si-NTI resist pattern as an etching hard mask.
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Michihiro Shirakawa, Michihiro Shirakawa, Tadashi Omatsu, Tadashi Omatsu, Keiyu Ou, Keiyu Ou, Yasunori Yonekuta, Yasunori Yonekuta, Naoya Hatakeyama, Naoya Hatakeyama, Daisuke Asakawa, Daisuke Asakawa, Takashi Yakushiji, Takashi Yakushiji, Mitsuhiro Fujita, Mitsuhiro Fujita, Nanae Muraki, Nanae Muraki, "Challenges for immersion lithography extension based on negative tone imaging (NTI) process", Proc. SPIE 9779, Advances in Patterning Materials and Processes XXXIII, 97790O (25 March 2016); doi: 10.1117/12.2218939; https://doi.org/10.1117/12.2218939

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