PURPOSE: To prevent the generation of vertical wall-shaped residue at a time when plasma etching is conducted by isotropic-etching a first insulating layer formed onto a conductive layer, forming a second insulating layer onto the first insulating layer and anisotropic-etching the second insulating layer.

CONSTITUTION: A gate insulating film 2 is formed onto a semiconductor substrate 1. A polysilicon film is formed, an insulating film 4 is shaped, and a resist 5 is formed in a specified region on the insulating film 4. The insulating film 4 is isotrpic-etched until the film pressure of the insulating film 4 reaches one fifth or a half, and the residual section of the insulating film 4 is anisotropic-etched. The resist 5 is removed, and the polysilicon film 3 is anisotropic-etched. Impurity ions are implanted to the semiconductor substrate 1. An insulating film 6 is formed on the whole surface. Sidewalls 6a are formed. Impurity ions are implanted to the semiconductor substrate 1. A resist 8 is shaped onto a polysilicon film 7. The polysilicon film 7 is anisotropic-etched. The resist 8 is removed, and insulating films 51, 52 are formed.