Patent ID: 7651792

Claim:
A multilayer hard film comprising at least one assemblage of a Layer A or a Layer B with a Layer C arranged alternately, wherein the Layer A is a hard film consisting of [(Nb 1−d , Ta d ) a Al 1−a ](C 1−x N x ), wherein “a”, “d”, and “x” each independently represent an atomic ratio and satisfy the following conditions: 0.4<a<0.6, 0<d<1, and 0.4<x<1, wherein, the Layer B is a hard film consisting of [(Nb 1−d ,Ta d ) a Al 1a−b−c ,Si b ,B c ](C 1−x N x ), wherein “a”, “b”, “c”, “d”, and “x” each independently represent an atomic ratio and satisfy the following conditions, provided that one of “b” and “c” may be zero but both of them are not simultaneously zero: 0.4<a<0.6, 0<b+c<0.15, 0<d<1, and 0.4<x<1, and wherein the Layer C is a hard film consisting of (Nb 1−D ,Ta D ) A ,Al 1−A−B−C, Si B ,B C ](C 1−x N x ), wherein “A”, “B”, “C”, “D”, and “x” each independently represent an atomic ratio and satisfy the following conditions, provided that one of B and C may be zero but both of them are not simultaneously zero: 0.2≦A≦0.5, 0.15<B+C≦0.5, 0≦D≦1, and 0.4≦x≦1.