APPLICATIONS OF PHOTOINITIATORS TO THE DESIGN OF RESISTS FOR SEMICONDUCTOR MANUFACTURING.

Acids generated via radiolysis of cationic photoinitiators, such as aryldiazonium, diaryliodonium, and triarylsulfonium metal halides can induce a variety of chain reactions in polymers, including cross-linking, catalytic deprotection, and catalytic depolymerization. All of these reactions can be exploited in the design of resist materials. When formulated with the onium salt photoinitiators, epoxy resins undergo efficient cross-linking reactions to provide negative tone resists, and poly(p-t-butoxy carbonyloxystyrene) is converted to poly(p-hydroxystyrene) in the exposed areas to provide either a positive or negative resist tone depending on the developer employed; and polyaldehydes are completely reverted to monomer upon exposure and vaporize during the exposure to provide self-developing positive resists. The extremely high sensitivity of these systems is achieved through chemical amplification.