| CPC H01L 21/0337 (2013.01) [G03F 1/32 (2013.01); H01L 21/0332 (2013.01)] | 9 Claims |
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1. A photomask blank comprising a transparent substrate, a first inorganic film which comprises silicon and is free of chromium, and a second inorganic film which comprises chromium and is free of silicon, the first inorganic film and the second inorganic film being in contact, the first inorganic film being formed on the transparent substrate via two or more inorganic films, wherein a ratio of an etching rate of the second inorganic film to an etching rate of the first inorganic film is not less than 0.3 at a fluorine-based dry etching performed under a same condition, wherein
said two or more inorganic films comprise a third inorganic film which comprises chromium and is free of silicon, and a fourth inorganic film which comprises silicon and is free of transition metals, wherein
the second inorganic film has a chromium content of not less than 20 at % and not more than 40 at % and a thickness of not less than 1 nm and not more than 10 nm,
the third inorganic film is in contact with the transparent substrate side of the first inorganic film, and has a chromium content of not less than 35 at % and a thickness of not less than 40 nm and not more than 100 nm, and
the fourth inorganic film is in contact with the transparent substrate side of the third inorganic film.
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