METHOD FOR PREPARING HALFTONE PHASE SHIFT MASK BLANK, HALFTONE PHASE SHIFT MASK BLANK, HALFTONE PH

A halftone phase shift mask blank comprising a transparent substrate and a halftone phase shift film thereon is prepared through the step of depositing the halftone phase shift film on the substrate (S) by using a sputtering gas containing rare gas and nitrogen gas, and plural targets (T) including at least two silicon targets in a particular arrangement, applying powers of different values to the silicon targets (T), effecting reactive sputtering in the transition mode, and rotating the substrate on its axis in a horizontal direction. The halftone phase shift film has satisfactory in-plane uniformity of optical properties.