Patent ID: 8349698

Claim:
A method of manufacturing an integrated semiconductor device, the method comprising; in a wafer comprised of a substrate, a first insulation film arranged on the substrate, and a semiconductor layer arranged on the first insulation film, forming a trench on the semiconductor layer and extending from a main surface of the semiconductor layer towards the first insulation film in order to separate into a plurality of semiconductor component areas, so that a part which has a smaller thickness than a thickness of the semiconductor layer between the main surface of the semiconductor layer and the first insulation film, remains between the first insulation film and the trench; and forming a second insulation film which covers a wall surface of the trench and contacts with the first insulation film, by oxidizing a part which is exposed on the trench of the semiconductor layer, wherein forming the second insulation film includes: a process for introducing impurities with a first concentration along a main side surface of the trench from an entrance of the trench of the semiconductor layer to the remaining part having a small thickness, and introducing the impurities with a second concentration which is higher than the first concentration along the remaining part having the small thickness; and a process for forming the second insulation film by performing a heating process in an oxidation atmosphere on the semiconductor layer introduced with the impurities, and an oxide film on the remaining part on the wall surface of the trench is formed thicker than an oxide film on other parts on the wall surface of the trench.