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Semiconductor device which includes multiple isolated semiconductor segments on one chip

  • US 5,138,422 A
  • Filed: 11/06/1991
  • Issued: 08/11/1992
  • Est. Priority Date: 10/27/1987
  • Status: Expired due to Term
First Claim
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1. A semiconductor device which comprises:

  • a semiconductor substrate made of a single crystal semiconductor substance;

    an insulating film formed locally at a predetermined region on a main surface of the substrate;

    a polycrystalline semiconductor layer formed on said insulating film;

    a single crystal semiconductor layer formed on said substrate and on said polycrystalline semiconductor layer;

    at least one isolation region formed to extend from a top main surface of said single crystal semiconductor layer to at least a surface of said insulating film, through said polycrystalline semiconductor layer and formed substantially vertical to a surface of the substrate, so as to electrically isolate at least a first portion formed in said single crystal semiconductor layer which is provided on said insulating film and surrounded by said isolation region, from a second portion formed in said single crystal semiconductor layer which is provided on said substrate, and not surrounded by said isolation region;

    at least a first semiconductor device formed on a main surface of or inside said first portion, for controlling a device formed in a main surface of or inside said second portion; and

    at least a second semiconductor device formed on said main surface of or inside said single crystal semiconductor layer forming said second portion on said substrate and not provided with said insulating film thereon, and using another main surface of the substrate opposite to said main surface having said insulating film thereon as a drain electrode to form a power semiconductor device using said second semiconductor device which is controlled by said first semiconductor device, wherein said single crystal semiconductor layer formed on a surface of said substrate in said second portion comprises at least two different unit layers having different amounts of impurities therein, respectively, one of said unit layers adjacent to said substrate has a surface in a same plane as a surface of said polycrystalline semiconductor layer that is formed on the surface of said insulating film.

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