PRODUCTION OF PHASE SHIFT MASK

摘要

PURPOSE:To make it possible to etch a transparent film for forming the phase shifters of the phase shift mask by a dry process while maintaining high selectivity of a glass substrate. CONSTITUTION:A thin SiOxNy stopping layer 3 is formed to cover Cr light transparent layers 2 formed on the glass substrate 1 and the surface thereof in flattened by a transparent SiOx film 4 to form a resist mask 5. The refractive indices of the SiOxNy stopping layer 3 and the transparent SiOx film 4 are previously matched. Free S (sulfur) in plasma bonds to the dangling bonds of the N atom formed on the surface of the SiOx stopping layer 3 at the point of the time when its surface is exposed if the transparent SiOx film 4 is etched by using gaseous S2F2. A surface protective film mainly consisting of polythiazyl (SN)x is thereby formed and the high selectivity is attained. The exposed parts of the SiOxNy stopping layer 3 are thereafter etched away to complete the phase shifters 6.