Patent ID: 7452795

Claim:
A method for fabricating a semiconductor device comprising the steps of: sequentially forming over a substrate an insulating film, a first mask, and a second mask whose etching characteristics are different from those of the first mask; forming on the second mask a photoresist film exposing a via-hole forming region; anisotropically etching the second mask and the first mask in the via-hole forming region with the photoresist film as a mask; anisotropically etching the insulating film in the via-hole forming region down to the middle thereof with the photoresist film, the second mask and the first mask as a mask; removing the second mask in an interconnection trench forming region containing the via-hole forming region; isotropically etching the first mask with the second mask as a mask to expose an upper surface of the insulating film at a peripheral region of the via-hole forming region and to leave the first mask in the interconnection trench forming region except the peripheral region; anisotropically etching the first mask and the insulating film with the second mask as a mask to form in the insulating film a via-hole having an increased-width portion at an upper part and an interconnection trench connected to the increased-width portion of the via-hole; and filling an interconnection in the via-hole and the interconnection trench.