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Power MOSFET with metal filled deep source contact

  • US 10,707,344 B2
  • Filed: 11/20/2017
  • Issued: 07/07/2020
  • Est. Priority Date: 01/18/2016
  • Status: Active Grant
First Claim
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1. A planar gate power metal-oxide-semiconductor field effect transistor die (power MOSFET), comprising:

  • a substrate having a semiconductor surface layer doped a first conductivity type over a bulk substrate, the semiconductor surface layer having a top side and the bulk substrate having a backside opposite the semiconductor surface layer;

    a plurality of transistor cells (cells) including a first cell and at least a second cell formed on the top side of the semiconductor surface layer, the first cell having a first gate stack and the second cell having a second gate stack;

    each gate stack including a gate electrode on a gate dielectric over a body region;

    a trench having an aspect ratio of at least 3 extending down from the top side of the semiconductor surface layer between the first gate stack and the second gate stack providing a source contact (SCT) from the substrate to a source doped a second conductivity type, and further comprising a substrate contact region at a bottom of the SCT, wherein the substrate contact region is doped the first conductivity type and extends from the semiconductor surface layer into the bulk substrate, the backside of the bulk substrate electrically coupled to the source;

    a field plate (FP) over the first and second gate stacks extending to provide a liner for the trench;

    the trench having a refractory metal or platinum-group metal (PGM) filler (metal filler) within the trench, anda drain doped the second conductivity type in the semiconductor surface layer on a side of the first gate stack opposite the trench and on a side of the second gate stack opposite the trench.

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