A halftone phase shift mask blank comprising a transparent substrate and a halftone phase shift film thereon is provided. The halftone phase shift film includes at least one layer composed of a silicon base material having a transition metal content≤3 at %, a Si+N+O content≥90 at %, a Si content of 30-70 at %, a N+O content of 30-60 at %, and an O content≤30 at %, and having a sheet resistance≤1013/Ω/□. The halftone phase shift film undergoes minimal pattern size variation degradation upon exposure to sub-200 nm radiation, and has chemical resistance and improved processability.