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Trench DMOS power transistor with field-shaping body profile and three-dimensional geometry

DC
  • US 5,072,266 A
  • Filed: 12/27/1988
  • Issued: 12/10/1991
  • Est. Priority Date: 12/27/1988
  • Status: Expired due to Term
First Claim
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1. A trench DMOS transistor cell comprising:

  • a substrate of semiconductor material of heavily doped first electrical conductivity type;

    a first covering layer of semiconductor material of said first electrical conductivity type lying on the substrate;

    a second covering layer of semiconductor material of second electrical conductivity type lying on the first covering layer;

    a third covering layer of semiconductor material of heavily doped said first electrical conductivity type and having a top surface and partly lying over the second covering layer, wherein a portion of the second covering layer is heavily doped and this portion extends both vertically upward and downward, an upward portion extending through the third covering layer to the top surface of the third covering layer and a downward portion extending downward into the first covering layer;

    a trench having a bottom surface and side surfaces and extending vertically downward from the top surface of the third covering layer through the third covering layer and the second covering layer and through a portion of the first covering layer, wherein the bottom surface of the trench lies above a lowest part of the downward portion of the second covering layer;

    electrically conducting semiconductor material positioned within the trench;

    a layer of oxide positioned within the trench between the electrically conducting semiconductor material and the bottom and side surfaces of the trench; and

    three electrodes electrically coupled to the electrically conducting semiconductor material, to the third covering layer and to the substrate, respectively.

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