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Non-volatile semiconductor memory device

  • US 4,774,556 A
  • Filed: 07/21/1986
  • Issued: 09/27/1988
  • Est. Priority Date: 07/25/1985
  • Status: Expired due to Term
First Claim
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1. A non-volatile semiconductor memory device comprising:

  • a semiconductor substrate of a first conductivity type;

    an impurity buried layer of a second conductivity type, different from said first conductivity type, formed at a surface of said semiconductor substrate, and constituting one of a drain region and a source region of a transistor of said semiconductor memory device;

    an epitaxial layer of said second conductivity type formed at a surface of said impurity buried layer;

    an insulating well extending from a surface of said epitaxial layer to said impurity buried layer, to form an independent vertical channel region coupled to said epitaxial layer;

    an impurity surface region of said second conductivity type formed at a surface of said independent vertical channel region and constituting the other of said drain region and said source region of said transistor;

    at least two electron accumulating regions formed in said insulating wall, separately facing said independent vertical channel region;

    a first insulation film between said electron accumulating regions and said insulating walls, of a thickness to cause an induced tunnel effect; and

    at least two control gate electrodes and a second insulation film, said at least two control gate electrodes extending vertically in said insulating wall, and separately facing each of said electron accumulating regions with said second insulation film therebetween, and controlling a conductivity of said independent vertical channel region between said impurity buried layer and said impurity surface region.

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