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Semiconductor device having a gate electrode in a grove and a diffused region under the grove

  • US 5,714,781 A
  • Filed: 04/26/1996
  • Issued: 02/03/1998
  • Est. Priority Date: 04/27/1995
  • Status: Expired due to Term
First Claim
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1. A semiconductor device comprising:

  • a semiconductor substrate having a first conductivity type semiconductor region at a main surface thereof, said semiconductor substrate having within said semiconductor region a concave portion which has a bottom surface and a sidewall surface;

    a body region of a second conductivity type formed within said semiconductor region and in contact with said sidewall surface of said concave portion;

    a source region of said first conductivity type formed within said body region, wherein a channel region is defined at said sidewall surface of said concave portion by a portion of said body region between said source region and said semiconductor region;

    a gate insulating film disposed to cover said sidewall surface and said bottom surface of said concave portion;

    a gate electrode disposed on said concave portion to be insulated with said gate insulating film; and

    an impurity diffusion region disposed at said bottom surface of said concave portion;

    wherein said gate insulating film covering said bottom surface of said concave portion has a distribution in thickness thereof such that a thickness becomes thicker closer to a central portion of said bottom surface of said concave portion, and a thickness of said gate insulating film at said central portion of said bottom surface of said concave portion is controlled to be thicker than a thickness of said gate insulating film at said sidewall surface of said concave portion.

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