Photomask and photomask blank

Abstract

In a low reflection type photomask (hard mask) having a tantalum masking film provided, through or without an intermediary low reflection layer, on a transparent substrate and further having a low reflection layer provided on the tantalum layer, use is made of a composite layer containing tantalum oxide and tantalum nitride as the low reflection layer. The etching speed of the composite layer is faster than that of the tantalum oxide layer conventionally used as low reflection layer, being substantially equal to that of the tantalum film, and there is very little lowering of the dimensional precision of the photomask obtained due to the difference in etching speeds. Further, dry etching is applicable for the above multilayer masking film containing the composite layer and the masking tantalum film, and there is little lowering of the dimensional precision even by overetching.

Dependencies are inferred from the claim text.