Photomask blank and photomask

A photomask blank in form of a phase shift mask blank,

• from which a photomask comprising a transparent substrate and a mask pattern formed thereon can be produced, comprising:
• a transparent substrate;
• and
• a light-shielding film, an antireflective film and another film (A), wherein
• the light-shielding film and the antireflective film are formed on the transparent substrate with the other film (A) intervening therebetween,
• the other film (A) comprises a phase shift film,
• the light-shielding film comprises one or more layers, at least one layer (B) of the layers containing silicon and a transition metal as main components,
• the silicon and the transition metal are present at a silicon/metal molar ratio of 4/1 to 15/1, and
• combination of the light-shielding film, the antireflective film and the phase shift film has an optical density of at least 2.5.