Patent ID: 8858814

Claim:
A photomask blank comprising: a transparent substrate; a film formed on the transparent substrate, the film consisting of one or more layers including an uppermost layer composed of a chromium base material; and an etching mask film on the uppermost layer, the etching mask film serving as an etching mask for the uppermost layer upon chlorine dry etching, wherein said etching mask film is deposited from a silicon oxide base material film-forming composition comprising: (A) a hydrolytic condensate of a hydrolyzable silane compound; (B) a compound having the general formula (1) or (2): L a H b X (1) wherein L is lithium, sodium, potassium, rubidium or cesium, X is a hydroxyl group or a mono- or polyfunctional organic acid group of 1 to 30 carbon atoms, a is an integer of at least 1, b is 0 or an integer of at least 1, and a+b is equal to the functionality of the hydroxyl or organic acid group, MA (2) wherein M is tertiary sulfonium, secondary iodonium or quaternary ammonium, and A is a non-nucleophilic counter ion; and (C) an organic solvent, and said etching mask film has a thickness of 1 to 10 nm.