Phase-shift photomask-blank, phase-shift photomask and fabrication method thereof

摘要

On a substrate that is transparent to exposure light, a phase-shift multilayer film including a stack of two layers of a metal silicide compound is formed. A stabilized oxide layer is formed on the surface of the metal silicide compound layer close to the top surface. The layer close to the substrate (the lower layer) of the phase-shift multilayer film is made of a relatively-metal-rich metal silicide compound, and the upper layer is made of a relatively-metal-poor metal silicide compound. The stabilized oxide layer has a metal-poor composition, and the metal content thereof is equal to or less than one third of the metal content of the lower layer. Thus, the stabilized oxide layer is highly chemically stable and has a high chemical resistance.