Patent ID: 8389184

Claim:
A reflective mask blank for use in EUV lithography using EUV light as exposure light, comprising; a substrate; a multilayer reflective film which is formed on the substrate and adapted to reflect the exposure light; and an absorber film which is formed on the multilayer reflective film and adapted to absorb the exposure light, wherein the absorber film has a laminated structure comprising an uppermost layer and a lower layer other than the uppermost layer, wherein the uppermost layer is formed of a material containing one of an oxide, a nitride, an oxynitride, and a carbide of tantalum (Ta) and has a refractive index n in a range of 0.95 to 0.97 and an extinction coefficient k in a range of −0.033 to −0.023, and wherein the lower layer is formed of a material containing tantalum (Ta) and has a refractive index n in a range of 0.94 to 0.97 and an extinction coefficient k in a range of −0.050 to −0.036.