Method of producing a patterned photoresist used to prepare high performance photomasks

Abstract

We are able to significantly reduce variations in critical dimension from target for features in a patterned photoresist, where the patterned photoresist is generated during the fabrication of a reticle (photomask) to be used in semiconductor processing. The ability to maintain the targeted critical dimension of patterned photoresist features which were imaged using a direct write process depends upon the use of a photoresist binder resin system which provides a sufficiently dense structure to sterically hinder the movement of photoacid-labile groups after irradiation of such groups (writing of the pattern). As importantly, the photoacid groups which are used to generate the pattern need to be such that they are activated only at temperatures above about 70° C., and preferably at temperatures in the range of 110° C. to 150° C. Further improvement in uniformity of developed photoresist feature size across the reticle surface is achieved by controlling a combination of variables during development.