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Method of making MOSFET by multiple implantations followed by a diffusion step

  • US 4,599,118 A
  • Filed: 09/24/1984
  • Issued: 07/08/1986
  • Est. Priority Date: 12/30/1981
  • Status: Expired
First Claim
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1. A method for manufacturing a metal oxide semiconductor transistor device comprising:

  • providing a semiconductor substrate of a first conductivity type;

    forming a first insulating layer of silicon dioxide on an active surface of the substrate;

    implanting ions of a first conductivity type into said substrate;

    depositing a layer of polysilicon on said first insulating layer;

    implanting ions of a second conductivity type through said polysilicon layer;

    growing a second region of silicon dioxide, said silicon dioxide region being grown over said polysilicon layer;

    placing a photoresistive mask over said second oxidation layer for forming a gate of the semiconductor device;

    etching a predetermined portion of said second oxidation layer;

    plasma etching said polysilicon layer;

    removing a predetermined portion of said polysilicon layer underneath said second silicon dioxide layer;

    etching said second layer of silicon dioxide;

    stripping said photoresist area from said second oxidation layer;

    implanting ions of the second conductivity type;

    implanting ions of the first conductivity type;

    etching said second layer of silicon dioxide overhanging said polysilicon gate layer;

    etching said first layer of silicon dioxide surrounding said polysilicon gate layer;

    implanting ions of said first conductivity type;

    implanting ions of said second conductivity type;

    diffusing the implanted ions into said substrate; and

    oxidizing the active surface of said substrate, including said polysilicon gate.

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