Patent ID: 7595236

Claim:
A method for production of a semiconductor device having a first insulating film, a second insulating film as an interlayer insulating film and a third insulating film on a substrate in this order and having a hole extending through the first insulating film, the second insulating film and the third insulating film, the method comprising: depositing the first insulating film, the second insulating film and the third insulating film on the substrate in this order; forming a first hole extending through the third insulating film along a direction of the thickness thereof; forming a second hole in the second insulating film in the lower part of the first hole to a depth at which a bowing shape does not occur by anisotropic etching using the third insulating film as a mask; forming a fourth film on the side surfaces of the first and the second holes; forming a third hole of an aspect ratio greater than twelve by extending the second hole until the first insulating film is exposed by carrying out anisotropic etching using the third insulating film and the fourth film as a mask and using the first insulating film as an etching stopper; removing the first insulating film exposed in the lower part of the third hole by anisotropic etching; and extending a side surface portion of the third hole, on which the fourth film is not formed, by isotropic etching using the third insulating film and the fourth film as a mask.