METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device capable of eliminating film thickness reduction in a trench element isolation structure while preventing deterioration in transistor characteristics without increasing the number of steps.SOLUTION: A method for manufacturing a semiconductor device comprises the steps of: forming a trench 2 by etching a trench element isolation region of a silicon substrate 1; forming an STI layer 3 composed of a thermal oxide film in the trench 2; depositing a polysilicon film 7 on the silicon substrate 1 in which the STI layer 3 is formed; forming an ON film 10 on the polysilicon film 7; forming a floating gate electrode 13 composed of the polysilicon film 7 on a memory region of the silicon substrate 1 by etching the ON film 10 and the polysilicon film 7 and exposing the STI layer 3 from under the ON film 10 and the polysilicon film 7; and covering the STI layer 3, the floating gate electrode 13, and the ON film 10 by depositing a protective oxide film 20 on the silicon substrate 1 by a CVD method.