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Semiconductor SRAM with trench transistors

  • US 5,324,973 A
  • Filed: 05/03/1993
  • Issued: 06/28/1994
  • Est. Priority Date: 05/03/1993
  • Status: Expired due to Fees
First Claim
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1. A semiconductor device comprising:

  • a semiconductor substrate having a surface;

    first and second trenches in the substrate;

    a first MOS transistor in the first trench, the MOS transistor having a first buried, drain region adjacent to the first trench;

    a second MOS transistor in the second trench, the second MOS transistor having a second, buried drain region adjacent to the second trench; and

    an electrically-conductive interconnect layer filling a central portion of the second trench and extending onto the surface of the substrate,wherein the second buried drain region electrically couples the interconnect layer to the first buried drain region, andwherein the first buried drain region is located a first distance from the substrate surface, and the second buried drain region is located a second distance from the substrate surface, and wherein the second distance is less than the first distance.

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