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Trenched DMOS transistor fabrication having thick termination region oxide

  • US 5,639,676 A
  • Filed: 02/16/1996
  • Issued: 06/17/1997
  • Est. Priority Date: 08/15/1994
  • Status: Expired due to Term
First Claim
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1. A method for forming a field effect transistor comprising the steps of:

  • providing a semiconductor substrate having a principal surface and being of a first conductivity type;

    forming a patterned mask layer on the principal surface;

    forming a doped deep body region of a second conductivity type of the transistor in a portion of the substrate underlying the portions of the principal surface exposed by the patterned mask layer;

    locally growing oxide on the principal surface at those portions of the principal surface exposed by the patterned mask layer including on a portion of a termination region of the transistor and extending to an outer edge of the termination region beyond an outer edge of an underlying doped region;

    removing the patterned mask layer, thereby exposing additional portions of the principal surface; and

    forming in those portions of the substrate underlying the exposed additional portions of the principal surface a doped body region, a doped source region, and a gate region of the transistor.

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