Patent ID: 9029237
Filing Date: 2015-05-12
Classification: H01L

Abstract:
1. A method of manufacturing a semiconductor device comprising the steps of: forming a mask layer for forming a trench in the main surface of a semiconductor substrate; forming a first trench having a first width and a prescribed depth so as to sandwich a first region in the semiconductor substrate, and forming a second trench having a second width narrower than the first width and a prescribed depth so as to sandwich a second region in the semiconductor substrate, by etching the semiconductor substrate using the mask layer as a mask; forming a first insulating film over the semiconductor substrate so as to be embedded in the first trench and the second trench; annealing the first insulating film; removing the first insulating film over the surface of the mask layer so as to be left in the first trench and the second trench; lowering the position of the upper surface of the first insulating film left in the first trench, and lowering the position of the upper surface of the first insulating film left in the second trench than the position of the upper surface of the first insulating film left in the first trench by a wet etching of the first insulating film left in each of the first trench and the second trench; forming a second insulating film having a density higher than that of the annealed first insulating film over the semiconductor substrate so as to cover the first insulating film left in the first trench and the first insulating film left in the second trench; adjusting the height of the second insulating film by etching the second insulating film so that the second insulating film in the first trench is not left, and that the second insulating film in the second trench is left; and removing the mask layer.