A novel chemically amplified positive deep UV photoresist with significantly reduced sensitivity to environmental contamination

Abstract

t‐Boc protected Deep‐UV transparent polymers with photoacid generators have been widely investigated as potential positive deep‐UV resist systems. However, utility of these systems is seriously handicapped by environmental contaminants leading to an insoluble “surface skin” formation. Only with a specially controlled environment or by use of an “overcoat” material is the performance of these systems acceptable. We have investigated a series of t‐Boc protected poly(styrene‐maleimide) copolymers and poly(hydroxy styrene) polymers with onium‐salts. Upon incorporation of a special class of organic additive, the surface effects inherent to these positive deep‐UV systems are significantly reduced thereby avoiding any extraneous precaution of protecting the resist surface from a typical manufacturing environment. We evaluated these t‐Boc polymer/onium‐salt systems with different additives under a varied set of processing conditions. In addition, plausible structure‐activity relationship of these additives in controlling the surface effects is presented.

Synthesis ofN‐Substituted Maleimides and Poly(styrene‐co‐N‐maleimide) Copolymers and Their Potential Application as Photoresists

“…[8] Chatterjee et al investigated t-BOC protected maleimide-styrene copolymer with onium salts as a positive deep-UV (DUV) resist combined with a series of additives to control the surface effects. [9] Schaedeli et al examined the performance of copolymers of p-hydroxystyrenes and N-substituted maleimides as DUV resist as a function of the molecular weight and monomer ratio. [10] Chiang et al have demonstrated the use of various maleimidebased copolymers as DUV or near DUV photoresists.…”

Terpolymers of tosyloxymaleimide for application as a polymeric photoacid generator in single-component resists.

“…Only a few polymaleimides have been investigated their applicability as thermally stable resist materials in DUV region based on the chemical amplification concept. Those polymaleimides are the styrenic copolymers of N-(t-butyloxycarbonyl)maleimide (t-BOCMI) [2][3][4][5], t-BOC protected N-(phydroxyphenyl)maleimide [b], and N-(t-butoxy)maleimide (t-BuOMI). [7] Recently we have reported the functional polymers of N-tosyloxymaleimide (TsOMI) which generate p-toluenesulfonic acid (TsOH) effectively by DUV irradiation.…”