Patent ID: 7611994

Claim:
A method of manufacturing a semiconductor device, comprising: forming an insulation film on a semiconductor substrate; forming a stopper film on the insulation film, the stopper film having a large etching selectivity relative to the insulation film and having a first film thickness; forming a first mask material on the stopper film, the first mask material having a second film thickness that is less than the first film thickness; forming a first mask by patterning the first mask material using an inversion mask having a final dimension; forming an opening portion wider than the first mask by etching the stopper film using the first mask, thereby performing a process causing the stopper film to have a pattern thinner than the first mask; filling the opening portion with a second mask material; forming a second mask of the second mask material by removing the first mask and the stopper film, the second mask having a thickness which is greater than the second film thickness; and etching the insulation film deeper than the first film thickness using the second mask.