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Trenched DMOS transistor fabrication using six masks

  • US 5,316,959 A
  • Filed: 08/12/1992
  • Issued: 05/31/1994
  • Est. Priority Date: 08/12/1992
  • Status: Expired due to Term
First Claim
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1. A method for forming a field effect transistor comprising:

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

    forming a patterned mask layer on the principal surface;

    doping semiconductor regions of a second conductivity type in the portions of the substrate exposed by the mask layer, thereby forming deep body regions of the transistor;

    growing an oxide layer on the portions of the principal surface exposed by the mask layer;

    forming a plurality of trenches in the substrate;

    forming a layer of conductive material in the trenches and over at least a part of the oxide layer, the portion of the conductive material layer in the trenches being a gate of the transistor;

    forming doped first regions of the second conductivity type in the substrate extending from the portions of the principal surface not covered by the oxide layer or the layer of conductive material into the substrate;

    forming doped second regions of the first conductivity type extending from the unmasked portions of the principal surface into the substrate, the first and second doped regions respectively being body and source regions of the transistor;

    forming a patterned insulating layer overlying the principal surface and the conductive material layer; and

    forming a patterned interconnect layer overlying the principal surface and over the patternedinsulating layer and contacting the deep body, body,and source regions, and the gate electrode.

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