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High voltage power MOSFET having a voltage sustaining region that includes doped columns formed by trench etching and diffusion from regions of oppositely doped polysilicon

  • US 20030203552A1
  • Filed: 04/16/2003
  • Published: 10/30/2003
  • Est. Priority Date: 12/31/2001
  • Status: Active Grant
First Claim
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1. A method of forming a power semiconductor device comprising the steps of:

  • A. providing a substrate of a first or second conductivity type;

    B. forming a voltage sustaining region on said substrate by;

    1. depositing an epitaxial layer on the substrate, said epitaxial layer having a first conductivity type;

    2. forming at least one trench in said epitaxial layer;

    3. depositing in said trench a first layer of material having a second dopant of the second conductivity type;

    4. diffusing said second dopant to form a doped epitaxial region adjacent to said trench and in said epitaxial layer;

    5. depositing in said trench a second layer of material having a first dopant of the first conductivity type;

    6. interdiffusing the first and second dopants respectively located in the second and first layers of material to achieve electrical compensation in the first and second layers of material;

    C. forming over said voltage sustaining region at least one region of said second conductivity type to define a junction therebetween.

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