Photoacid generating polymers based on sulfonyloxymaleimides and application as single-component resists

Abstract

Three sulfonyloxymaleimides (RsOMI), N-(tosyloxy)maleimide (TsOMI), N-(methane-sulfonyloxy) maleimide (MsOMI), and N- (trifluoromethanesulfonyloxy)maleimide (TfOMI), have been synthesized and used to make novel photoacid generating polymers. The sulfonyloxymaleimides easily copolymerized with styrene derivatives to give high molecular weight polymers having an alternating structure of both monomer units. Terpolymers based on RsOMI and p-(tert-butyloxycarbonyloxy) styrene (t-BOCSt) were prepared for enhancing resist properties such as adhesion to substrates, solubility in aqueous alkaline solutions, or transparency in the deep-UV region. The RsOMI copolymers were found to produce corresponding sulfonic acids (RsOH), TsOH, MsOH, and TfOH, by deep-UV irradiation in the film state. Thus, the polymers having both the RsOMI and t-BOCSt units show the capability of a single-component, chemically amplified resist system in the deep-UV region without addition of any photoacid generator. Positive- and negative-tone images were obtained by exposure of the polymer films to deep-UV and post-exposure bake followed by development with organic solvents or aqueous alkaline solutions. (C) 1996 John Wiley & Sons, Inc.