Chemical amplification positive resists based on depolymerization

S Chemical amplification positive resists based on depolymerization 7.2.2.5.1 Poly(phthaldehyde) resist 

The solution to this problem was found when they used an anionic mechanism to prepare the poly(phthaldehyde) and a cationic mechanism involving the photogeneration of acid from a neutral species such as onium salts of the kind publicized 

Willson and R.A. Dammel, A. Reiser, Photoresist Materials A Historical Perspective, Proc. 5P/ 3050, pp. 38 51 (1997). 

Crivello and J.H. Lam, Photo initiated cationic polymerization with triarylsulfonium salts, J. Polym. Set Polym. Chem. Ed. 17, 977 (1979). 

Willson, and J.M.J. Frechet, New UV resists with negative or positive tone, Digest of Technical Papers, 1982 SPE Symp. on VLSI TechnoL, p. 6 (1982) C.G. Willson, H. Ito, J.M.J. Frechet, T.G. Tessier, F.M. Houlihan, Approaches toward the design of radiation sensitive poly meric imaging systems with improved sensitivity and resolution, J. Electrochem. Soc. 133, p. 181 (1986). 

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