REFLECTIVE MASK BLANK, REFLECTIVE MASK AND METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE

Provided are a reflective mask blank, having a phase shift film having little dependence of phase difference and reflectance on film thickness, and a reflective mask. The reflective mask blank is characterized in that the phase shift film is composed of a material comprised of an alloy having two or more types of metal so that reflectance of the surface of the phase shift film is more than 3% to not more than 20% and so as to have a phase difference of 170 degrees to 190 degrees, and when a group of metal elements that satisfies the refractive index n and the extinction coefficient k of k > α*n+β is defined as Group A and a group of metal elements that satisfies the refractive index n and the extinction coefficient k of k < α*n+β is defined as Group B, the alloy is such that the composition ratio is adjusted so that the amount of change in the phase difference is within the range of ±2 degrees and the amount of change in reflectance is within the range of ±0.2% when one or more types of metal element each is selected from the Group A and the Group B and the film thickness of the phase shift film has fluctuated by ±0.5% with respect to a set film thickness (provided that α: proportional constant, β: constant).