No 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.