HALFTONE PHASE SHIFT PHOTOMASK BLANK AND MAKING METHOD

摘要

A halftone phase shift photomask blank comprising a transparent substrate and a halftone phase shift film consisting of silicon, nitrogen and optional oxygen, and providing a phase shift of 150°-200° relative to light of wavelength up to 200 nm. The phase shift film includes at least one layer meeting the formula: 2×O/Si + 3×N/Si ‰¥ 3.5 wherein Si is a silicon content (at%), N is a nitrogen content (at%), and 0 is an oxygen content (at%). The phase shift film exhibits satisfactory in-plane uniformity of transmittance.