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Insulated gate semiconductor device

  • US 6,001,678 A
  • Filed: 09/25/1997
  • Issued: 12/14/1999
  • Est. Priority Date: 03/14/1995
  • Status: Expired due to Term
First Claim
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1. A method of manufacturing an insulate gate semiconductor device, comprising:

  • a substrate forming step of forming a semiconductor substrate defining first and second main surfaces and having a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type with a lower impurity concentration, said first semiconductor layer being exposed in said first main surface and said second semiconductor layer being exposed in said second main surface;

    a first implantation step of implanting and diffusing impurity of the second conductivity type to an impurity concentration higher than the impurity concentration of said second semiconductor layer into said second main surface of said semiconductor substrate to form a third semiconductor layer of the second conductivity type in a surface portion of said second semiconductor layer;

    a second implantation step of implanting and diffusing impurity of the first conductivity type in a surface of said third semiconductor layer to form a fourth semiconductor layer of the first conductivity type in a surface portion of said third semiconductor layer, wherein said third semiconductor layer is so formed as to be thinner after forming said fourth semiconductor layer than said second semiconductor layer remaining;

    a third implantation step of selectively implanting and diffusing impurity of the second conductivity type in a surface of said fourth semiconductor layer to selectively form a fifth semiconductor layer of the second conductivity type in a surface portion of said fourth semiconductor layer;

    a first removing step of forming a shield film having an opening surrounding a part of a surface of said fifth semiconductor layer on the surface of said fourth semiconductor layer and the surface of said fifth semiconductor layer and selectively removing a portion of said fifth semiconductor layer, a portion of said fourth semiconductor layer and a portion of said third semiconductor layer using the shield film as a mask to form a trench with a depth extending at least into said third semiconductor layer through said fourth semiconductor layer, and removing said shield film after that;

    a first step forming an insulating film on surfaces of said trench, said fourth semiconductor layer and said fifth semiconductor layer;

    a first provision step of providing a conductor on said insulating film so as to fill said trench;

    a second removing step of uniformly removing said provided conductor to the opening of said trench so as to leave the conductor in said trench as a control electrode;

    a second provision step of providing an insulating layer on the surface of said insulating film and a surface of the conductor buried in said trench;

    a third removing step of selectively removing said insulating layer and said insulating film in a region covering the surface of said fourth semiconductor layer and a part of the surface of said fifth semiconductor layer;

    a step of providing a conductor on the surfaces of said fourth and fifth semiconductor layers exposed by said third removing step to form a first main electrode; and

    a step of providing a conductor on said first main surface of said semiconductor substrate to form a second main electrode.

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