Blankophotomaske und Phasenverschiebungsmaske

摘要

A phase shift photomask and a photomask blank used to produce the same. A dry etching stopper layer (102), which is disposed between a substrate (101) and a light-shielding layer (103) or between the substrate and a phase shifter layer, is made of either a film mainly composed of tin oxide nitride, which has high etching selectivity and high permeability, or an alumina film formed by sputtering, followed by heat treatment carried out in an oxidizing atmosphere, thereby enabling the required overetching to be satisfactorily performed during etching of the phase shifter layer, and thus making it possible to effect precise phase control. In addition, it is possible to eliminate the occurrence of an in-plane transmittance distribution.