Patent ID: 6893575

Claim:
A method of manufacturing a mask comprising: forming an etching resistant film having a plurality of openings having a polygonal shape on surfaces of a monocrystal substrate having Miller indices {110}, each side of the openings being parallel to one of the {111} planes; and forming a plurality of penetrating holes in the monocrystal substrate within the openings by etching; wherein: the etching has a crystal orientation dependence that the etching speed with respect to the {111} planes is slower than the etching speed with respect to the {100} and {110} planes; opposite surfaces of the monocrystal substrate are the {110} planes; the etching resistant film having the openings is formed on the opposite surfaces; the etching is advanced in the opposite surfaces of the monocrystal substrate, depressed portions formed by the etching being made into penetrating holes the openings include first openings formed on one surface of the monocrystal substrate and second openings formed on the other surface of the monocrystal substrate, the first and second openings being correspondingly disposed to each other; and the second openings are smaller than the first openings, and are formed inside a projecting area of the first openings.