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Trench field effect transistor and method of making it

  • US 20070141783A1
  • Filed: 02/23/2005
  • Published: 06/21/2007
  • Est. Priority Date: 03/03/2004
  • Status: Active Grant
First Claim
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1. A method of manufacturing an insulated gate field effect transistor;

  • including;

    providing a substrate having a first major surface having a low-doped region at the first major surface, the low-doped region having a concentration of less than 5×

    1014 cm

    3
    at the first major surface;

    forming gate trenches extending from the first major surface;

    forming trench insulator on the base and sidewalls of the gate trenches;

    implanting dopants of a first conductivity type at the base of the trenches;

    implanting a body implant of second conductivity type opposite to the first conductivity type in the low-doped regions between the trenches;

    carrying out a diffusion step to form an insulated gate transistor structure in which the body implant diffuses towards the substrate in the low doped region to form a p-n junction between a body region doped to have the second conductivity type above a drain region doped to have the first conductivity type, the p-n junction being deeper below the first major surface between the trenches than at the trenches; and

    forming source regions at the first major surface adjacent to the trench.

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