Patent ID: 8329364

Claim:
A phase shift mask blank, which is an original plate of a phase shift mask exposed to an ArF excimer laser light, wherein: the phase shift mask blank has a light transmissive substrate, a phase shift film and a light-shielding film; the phase shift film is provided between the light transmissive substrate and the light-shielding film; the phase shift amount of the phase shift film with respect to the ArF excimer laser light is 160° to 200° and the transmittance of the phase shift film is 2 to 40%; the light-shielding film has a laminated structure in which a lower layer, an interlayer and an upper layer are laminated in this order from the side close to the light transmissive substrate; the thickness of the entire light-shielding film is 60 nm or less; the lower layer is made of a film containing a metal and has a first etching rate; the upper layer is made of a film containing a metal and has a third etching rate; and the interlayer is made of a metallic nitride film, which contains the same metal as that contained in the lower layer or the upper layer and nitrogen, and has a second etching rate that is lower than the first etching rate and the third etching rate.