Patent ID: 7449411

Claim:
A method of manufacturing a semiconductor device comprising: forming a first conductive layer above a substrate; forming a first interlayer insulating layer over the first conductive layer; forming a second interlayer insulating layer on the first interlayer insulating layer; dry etching a first hole through the second interlayer insulating layer, beyond an interface between the first and the second interlayer insulating layers, to reach the first interlayer insulating layer; forming a protective film that covers a top surface of the second interlayer insulating layer and surfaces inside the first hole; removing the protective film formed at a bottom of the first hole, while maintaining the protective film that covers the top surface and sidewall in the first hole of the second interlayer insulating layer, and maintaining the protective film that covers the sidewall in the first hole of the first interlayer insulating layer, thereby forming a small hole in the protective film within the first hole; etching a second hole, via the small hole in the protective film, through the first interlayer insulating layer to the first conductive layer, thereby forming a contact hole including the first and second holes, a diameter of the second hole being smaller than a diameter of the first hole; removing the protective film that covers the surface of the second interlayer and the sidewall of the first and the second interlayer insulating layers; forming a second conductive layer over the second interlayer insulating layer and in the contact hole; and electrically connecting the first conductive layer and the second conductive layer via the contact hole.