Method of producing a semiconductor device

摘要

A trench is formed by performing an anisotropic etching treatment on a silicon substrate with the use of a mask pattern including a pad oxide film, a polysilicon film, and a silicon nitride film formed on the silicon substrate, as a mask. Next, the side surface of the polysilicon film is retreated by etching so that the part of an oxide film formed on the side surface of the polysilicon film may not be hung over the part of an oxide film formed on the side surface of the pad oxide film. Next, an oxide film is formed by performing a thermal oxidation treatment on the inner wall surface of the trench including the exposed side surface of the polysilicon film. This produces a semiconductor device that prevents voids from being formed in a trench isolation structure.