Patent ID: 11961921
Assignee: LAPIS SEMICONDUCTOR CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 3:
4. A manufacturing method for a semiconductor device, comprising:
a step of forming a trench that extends towards an interior of a semiconductor substrate from a first surface of the semiconductor substrate through dry etching;
a step of forming a semiconductor film doped with impurities so as to cover an inner wall surface of the trench, and continuously extend from the inner wall surface to the first surface of the semiconductor substrate;
a step of forming an insulating film on a surface of the semiconductor film; and
a step of forming, on the insulating film, an opposite electrode having a first portion that extends on the first surface of the semiconductor substrate and a second portion that is continuous with the first portion and extends so as to fill the trench;
wherein the step of forming the semiconductor film includes:
a first step of forming a first polysilicon film doped with impurities; and
a second step of forming a non-doped second polysilicon film on a surface of the first polysilicon film; and
wherein the first polysilicon film and the second polysilicon film are formed between the inner wall surface and the insulating film.