Method of producing phase shift masks

Abstract

A light-shielding film patternhaving a main openingand auxiliary openingsis formed in a first process and, then, recess etching of a transparent substrate (formation of a substrate etched portion) is performed in a second process. Thus, the main opening and auxiliary openings can be simultaneously exposed in the first process and the positioning accuracy of them becomes excellent. Patterning of a light-shielding filmis performed by the use of an etching mask layerand therefore the processing accuracy of the light-shielding film becomes excellent. The etching mask layeris removed in a third process as the final process and thus the light-shielding film patterncan be protected by the etching mask layerupon recess-etching the transparent substrate in the second process. Thus, it is possible to prevent damage to the light-shielding film patternin the recess etching of the transparent substrate. Specifically, the etching mask layeritself is damaged in the recess etching of the transparent substrate and this etching mask layeris removed in the third process, causing no problem.