Patent ID: 8753787

Claim:
A light pattern exposure method comprising irradiating a pattern of light to a resist film through a photomask using ArF excimer laser light as the light source, wherein the photomask used is such that it has been irradiated with ArF excimer laser light in a cumulative dose of at least 10 kJ/cm 2 , said photomask comprising a transparent substrate and a pattern of optical film of a material comprising a transition metal, silicon, and nitrogen and/or oxygen, the transition metal having potentially a valence of 6, the contents of transition metal, silicon, nitrogen and oxygen in the optical film meeting both the formulae (1) and (2): 6×C M /100−4×C Si /100≦−0.89 (1) 6C M ×3C N /(6C M ×6C M +6C M ×4C Si +6C M ×3C N +6C M ×2C O +4C Si ×4C Si +4C Si ×3C N +4C Si ×2C O )≧0.094 (2) wherein C M is a transition metal content in atom %, C Si is a silicon content in atom %, C N is a nitrogen content in atom % and C O is an oxygen content in atom %, except for an outermost surface region extending from the film surface remote from the substrate to a depth of 10 nm.