Patent ID: 7060394

Claim:
A halftone phase-shift mask blank for halftone phase-shift masks having, on a transparent substrate, a light-transmissive part that transmit an exposure light, and a phase shifter part that transmits a part of the exposure light and shifts the phase of the transmitted light to a predetermined degree; the mask blank having a phase shifter film to form the phase shifter part on the transparent substrate being characterized in that, the phase shifter film consists of two layers, said two layers respectively comprising a low-transmission layer having a principal function of transmittance control, and a high-transmission layer having a principal function of phase shift control, wherein an uppermost layer is said high-transmission layer, the extinction coefficient K1 of the low-transmission layer and the extinction coefficient K 2 of the high-transmission layer satisfy K 2 <K 1 ≦3.0 at the exposure light wavelength λ falling between 140 nm and 200 nm, and the thickness d 1 of the low-transmission layer satisfies 0.001≦K 1 d 1 /λ≦0.500 at the exposure light wavelength λ, wherein the high-transmission layer is SiON.