METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PURPOSE: To provide a method for manufacturing a semiconductor device to prevent an air gap from being formed in a trench isolation structure. CONSTITUTION: A trench is formed on a silicon substrate 1 by performing anisotropic etching using a mask pattern including a pad oxidation film formed on the silicon substrate 1, a polysilicon film 3a and a silicon nitride film 4a as a mask. Consequently, a side surface of the polysilicon 3a is removed by etching so that an oxidation portion formed on a side surface of the polysilicon 3a does not become an over hang shape relative to a side surface portion of the pad oxidation film. Finally, an oxidation film 7 is formed by performing a thermal oxidation treatment to an inner wall surface of the trench including the side surface of the exposed polysilicon film 3.