Patent ID: 8518609

Claim:
A photomask blank comprising: a transparent substrate; a light-shielding film formed on the transparent substrate, wherein the light-shielding film comprises: a light-shielding layer being made of a material containing tantalum nitride and containing 32 at % or less nitrogen; and a front-surface antireflection layer formed on the light-shielding layer, the front-surface antireflection layer being made of a material containing tantalum oxide and containing 50 at % or more oxygen, wherein the material of the light-shielding layer has a first refractive index n 1 of 2.20 or less and a first extinction coefficient k 1 of 2.05 or more, and the material of the front-surface antireflection layer has a second refractive index n 2 of 2.23 or more and a second extinction coefficient k 2 of 1.09 or less.