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Trench depletion MOSFET

  • US 5,581,100 A
  • Filed: 08/30/1994
  • Issued: 12/03/1996
  • Est. Priority Date: 08/30/1994
  • Status: Expired due to Term
First Claim
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1. A high power metal oxide semiconductor field effect trench transistor device exhibiting relatively low on-resistance and relatively high breakdown voltage, said device comprising:

  • a wafer of semiconductor material having first and second opposing semiconductor surfaces, said wafer of semiconductor material including a relatively lightly doped region of a first conductivity type, a plurality of spaced narrow trenches perpendicularly formed in said wafer and extending from said first semiconductor surface, at least a portion of said relatively lightly doped region being disposed between said trenches;

    gate electrode means disposed in said trenches and spaced from said portion of said relatively lightly doped region by a layer of gate insulation material;

    a first relatively highly doped region of said first conductivity type disposed between and adjacent to said first semiconductor surface and said relatively lightly doped region; and

    a first region of a second conductivity type opposite to said first conductivity type, said first region of said second conductivity type being formed in said wafer and extending from said first semiconductor surface adjacent, in a first planar direction, to said first relatively highly doped region of said first conductivity type and directly contacting, in a second planar direction orthogonal to said first planar direction, to said gate insulation material, thereby forming a MOSFET of said second conductivity type, said first region of said second conductivity type comprising a drain region of said MOSFET of said second conductivity type and forming a drain for carriers of said second conductivity type generated in said portion of said relatively lightly doped region of said first conductivity type between said gates to create a deep-depletion region therein and provide enhanced forward blocking capability for the device when a voltage is applied to said gate electrode means to turn off the device.

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