Patent ID: 7494883

Claim:
A method of fabricating a semiconductor device comprising an SOI substrate obtained by sequentially stacking a semiconductor substrate, a buried oxide film, and a semiconductor layer, the method comprising the steps of: (a) forming a first oxide film on said semiconductor layer; (b) forming a first insulating film on said first oxide film; (c) opening said first insulating film on said semiconductor layer by etching; (d) forming a trench having said semiconductor layer, said first oxide film and said first insulating film as an inner wall by penetrating said first oxide film and reaching a predetermined depth in said semiconductor layer of a portion of the opening of said first insulating film; (e) forming a first side wall spacer of a second insulating film on an inner wall of said trench, which extends from said semiconductor layer to said first insulating film; (f) implanting ions of an impurity of first conduction type with energy by which a peak of a profile is formed in said semiconductor layer under the bottom of said trench; (g) forming a trench isolation oxide film by filling said trench with a third insulating film in a state where said first side wall spacer is left; (h) forming a second oxide film after removing said first oxide film; (i) forming a polysilicon film on said second oxide film; (j) forming a gate oxide film and a gate electrode by patterning said second oxide film and said polysilicon film; (k) forming a second side wall spacer of a fourth insulating film on a side wall of said gate oxide film and said gate electrode; and (l) implanting ions of an impurity of second conduction type for a source/drain layer using said gate electrode and said second side wall spacer as an implantation mask.