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25 March 2010 Process feasibility investigation of freezing free litho-litho-etch process for below 32nm hp
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Double patterning with 193nm immersion lithography becomes to most promising candidate for 32nm half pitch node and possibly below 32nm half pitch. Several double patterning methods have been suggested such as LELE (Litho-Etch -Litho-Etch), LLE (Litho-Litho-Etch) and Spacer defined process, however, LLE process is pointed out as low cost double patterning technique because of its simplicity. But LLE process needs new method to maintain 1st lithography pattern and additional freezing processes have been suggested In SPIE Advanced Lithography 2009, freezing free "Posi/Posi" process was introduced as candidate for LLE process. This is LLE process that uses two different positive tone photoresists without freezing process. The resist for 2nd lithography contains a specific solvent to prevent the mixing of two resists and there is an activation energy gap between 1st and 2nd resists to maintain 1st lithography pattern. The double patterning can be successfully processed by these specific resists without freezing process. In this study, the performance of this freezing free "Posi/Posi" process is investigated for pitch splitting pattern using 1.35 NA exposure tool. The imaging results including CD control capability, and etching results are collected for 32nm half pitch and below. Additionally the two-dimensional pattern imaging is also obtained for 76nm minimum pitch.
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Tsuyoshi Nakamura, Masaru Takeshita, Jiro Yokoya, Yasuhiro Yoshii, Hirokuni Saito, Ryoichi Takasu, and Katsumi Ohmori "Process feasibility investigation of freezing free litho-litho-etch process for below 32nm hp", Proc. SPIE 7639, Advances in Resist Materials and Processing Technology XXVII, 76392V (25 March 2010);

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