CHEMICALLY AMPLIFIED RESISTS BASED ON POLYMER SIDE-CHAIN REARRANGEMENT OR ELECTROPHILIC CROSS-LINKING

A variety of resist systems have been studied that owe their sensitivity to the occurrence of catalyzed electrophilic rearrangements or substitution processes. In most designs, polyfunctional or polymer-bound benzylic ethers, esters, or alcohols are used in the key step of the reaction, which is initiated by protonation of the latent electrophilic moiety, resulting in formation of a carbocationic center. Thermal activation of the electrophilic process leads to the formation of new C-C bonds with liberation of a proton; therefore the overall process is catalytic and amounts to chemical amplification. A variety of polymers and active small molecules that provide access to both negative and positive tone images have been tested, and sensitivities as high as 0.1 mJ/cm2 have been measured. In addition, several image reversal schemes involving either selective silylation of non-exposed areas or the in situ photogeneration of base have been tested and are presented.