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Trench DMOS transistor having reduced punch-through

  • US 20010008788A1
  • Filed: 03/02/2001
  • Published: 07/19/2001
  • Est. Priority Date: 09/14/1999
  • Status: Active Grant
First Claim
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1. A method of forming a trench DMOS transistor cell comprising the steps of:

  • providing a substrate of a first conductivity type;

    forming a body region on the substrate, said body region having a second conductivity type;

    forming a masking layer defining at least one trench;

    forming the trench defined by the masking layer, said trench extending through the body region and the substrate;

    forming an insulating layer that lines the trench;

    forming a conductive electrode in the trench overlying the insulating layer;

    forming a source region of the first conductivity type in the body region adjacent to the trench; and

    wherein the step of forming the trench includes the steps of etching the trench and smoothing sidewalls of the trench with a sacrificial oxide layer before removal of the masking layer that defines the trench.

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