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Vertical current flow field effect transistor with thick insulator over non-channel areas

  • US 5,298,781 A
  • Filed: 07/08/1992
  • Issued: 03/29/1994
  • Est. Priority Date: 10/08/1987
  • Status: Expired due to Term
First Claim
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1. A transistor comprising:

  • a P-type first semiconductor region;

    an N-type second semiconductor region formed on said first semiconductor region;

    a P-type third semiconductor region formed on said second semiconductor region;

    a trench extending through said third and second semiconductor regions at least to said first semiconductor region;

    an insulating layer formed on the walls of said trench, a portion of said insulating layer adjacent said first semiconductor region being thicker than a portion of said insulating layer adjacent said second semiconductor region; and

    a gate formed in said trench, said gate being insulated from said first, second and third semiconductor regions by said insulating layer,wherein a portion of said insulating layer adjacent said third semiconductor region is thicker than said portion of said insulating layer adjacent said second semiconductor region.

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