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Trench DMOS transistor having a zener diode for protection from electro-static discharge

  • US 6,884,683 B2
  • Filed: 11/18/2003
  • Issued: 04/26/2005
  • Est. Priority Date: 05/22/2001
  • Status: Expired due to Term
First Claim
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1. A method of making a trench DMOS transistor having overvoltage protection, said method comprising the steps of comprising:

  • providing a substrate of a first conductivity type;

    forming a body region by an implantation of a second conductivity type on the substrate;

    forming at least one trench extending through the body region, wherein said body region is formed prior to the step of forming at least one trench;

    depositing an insulating layer that lines the trench and overlies said body region;

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

    implanting a dopant of the first conductivity type to form a source region in the body region adjacent to the trench;

    depositing an undoped polysilicon layer overlying a portion of the insulating layer; and

    implanting a dopant of the first conductivity type to form a plurality of cathode regions in the undoped polysilicon layer, said plurality of cathode regions being separated by at least one anode region.

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