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MOSFET structure and fabrication process implemented by forming deep and narrow doping regions through doping trenches

  • US 5,895,951 A
  • Filed: 04/05/1996
  • Issued: 04/20/1999
  • Est. Priority Date: 04/05/1996
  • Status: Expired due to Term
First Claim
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1. A MOSFET vertical cell formed in a substrate includes a source, a drain, and a channel for conducting source-to-drain current therethrough across a body region wherein said vertical cell being surrounded by a polysilicon layer acting as a gate for controlling said source-to-drain current through said channel, said MOSFET cell further comprising:

  • a doping trench filled with a trench-filling material;

    a deep-doped region disposed underneath said doping trench wherein said deep-doped region extends downwardly to substantially a total depth of an implant depth of said deep-doped region and a vertical diffusion depth below a bottom of said doping trench whereby said deep-doped region defining a buried region disposed below said body region; and

    said doping trench includes an insulation layer insulating said trench filling material from said substrate and said gate, and said doping trench is employed only for implanting dopant ions therethrough and serving no active electrical functions.

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