The decrease of dissolution rate in unexposed areas of chemically amplified three-component positive resist by means of tert-butyl carbonate as a dissolution inhibitor

Abstract

The dissolution characteristics of a chemically amplified electron beam (EB) resist composed of partially tert-butoxycarbonyl group (tBOC) protected poly(p-vinylphenol) (PVP), a dissolution inhibitor, and an acid generator were investigated. We tried to decrease the dissolution rate of the resist in the unexposed areas using dissolution inhibitors. We estimated the dissolution rate by using a model-composition resist which consists of tBOC-PVP as matrix resin and three differently oriented dihydroxybenzenes protected with tBOC as dissolution inhibitors. We evaluated the relationship between the melting point of dihydroxybenzens protected with tBOC and the dissolution rate of model-composition resist. The higher the melting point of dihydroxybenzen protected with tBOC, the lower the dissolution rate of model-composition resist. The higher the melting point of dihydroxybenzen protected with tBOC, the less the decomposition of the tBOC group of the dissolution inhibitors at prebake. We think that the polymer hardness becames softer by adding a dissolution inhibitor with a low melting point. The dissolution inhibitor with a low melting point acted as a flexibilizer in the model-composition resist. It was found that a dissolution inhibitor with a high melting point decreases the dissolution rate of a resist in the unexposed areas.