Patent ID: 7601635

Claim:
A manufacturing method of a semiconductor device having a nonvolatile memory cell, comprising the steps of: (a) forming a first insulating film over a semiconductor substrate; (b) forming a first polycrystalline silicon film over the first insulating film; (c) forming a second insulating film over the first polycrystalline silicon film; (d) forming a second polycrystalline silicon film over the second insulating film; (e) forming an W x Si y film over the second polycrystalline silicon film; (f) after the step (e), patterning the W x Si y film, the second polycrystalline silicon film, the second insulating film and the first polycrystalline silicon film; and (g) after the step (f), performing heat treatment, wherein the step (d) comprises steps of: (d1) forming a second region of the second polycrystalline silicon film over the second insulating film; and (d2) forming a first region of the second polycrystalline silicon film over the second region of the second polycrystalline silicon film, an impurity concentration of the first region of the second polycrystalline silicon film being smaller than that of the second region of the second polycrystalline silicon film, wherein, in the step (e), the W x Si y film is formed so as to satisfy y/x≧2, and wherein the W x Si y film formed in the step (e) has a resistivity of 1000 μΩcm or greater and has a resistivity of 400 μΩcm or less after the heat treatment in the step (g).