Investigation of onium salt type photoacid generators in positive DUV resist systems

Michael Francis Cronin; Timothy G. Adams; Theodore H. Fedynyshyn; Jacque H. Georger Jr.; J. Michael Mori; Roger F. Sinta; James W. Thackeray

doi:10.1117/12.175339

16 May 1994 Investigation of onium salt type photoacid generators in positive DUV resist systems

Michael Francis Cronin, Timothy G. Adams, Theodore H. Fedynyshyn, Jacque H. Georger Jr., J. Michael Mori, Roger F. Sinta, James W. Thackeray

Author Affiliations +

Proceedings Volume 2195, Advances in Resist Technology and Processing XI; (1994) https://doi.org/10.1117/12.175339
Event: SPIE's 1994 Symposium on Microlithography, 1994, San Jose, CA, United States

Abstract

The effect of onium salt structure in partially blocked poly(p- vinyl)phenol/photoacid generator (PAG) resist matrices on resolution, inhibition, and postexposure delay stability is reported. The PAG structure, M⁺X^-, was varied such that M⁺ was either triphenyl sulfonium (TPS⁺) or diphenyl iodonium (DPI⁺), and X^- represented trifluoromethanesulfonate (TFA^-) toluenesulfonate (TSA^-), camphorsulfonate (CSA^-), and hexadecylsulfonate (HDSA^-). The relative photospeed of these resists corresponded to the relative pK_a of the acid generated from the anoin, TFA>TSA>HDSA>CSA. The resolution of the resists using TPS⁺ were better than that of the DPI⁺-based resists. The best PAG from a resolution standpoint was triphenylsulfonium tosylate. The TPS⁺TSA_- also showed the lowest measured diffusion coefficient, D equals 1.1 X 10$=-4) micrometers ²/s. However, variation in PAG structure did not show any advantage in postexposure delay stability, with all the resists studied showing either 't-top' or scumming as failure modes. The larger acids, CSA and HDSA, showed a greater tendency to scum over a one hour delay period, which may indicate less acid evaporation, and more lateral diffusion to unexposed areas. The smaller acids, TSA and TFA, both showed strong 't-top' formation which is due to their increased acid volatility.

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Michael Francis Cronin, Timothy G. Adams, Theodore H. Fedynyshyn, Jacque H. Georger Jr., J. Michael Mori, Roger F. Sinta, and James W. Thackeray "Investigation of onium salt type photoacid generators in positive DUV resist systems", Proc. SPIE 2195, Advances in Resist Technology and Processing XI, (16 May 1994); https://doi.org/10.1117/12.175339

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