×

Method of making a three dimensional NAND device

  • US 9,305,849 B1
  • Filed: 11/12/2014
  • Issued: 04/05/2016
  • Est. Priority Date: 11/12/2014
  • Status: Expired due to Fees
First Claim
Patent Images

1. A method of making a monolithic three dimensional NAND string, comprising:

  • forming a stack of alternating layers of a first material and a second material different from the first material over a substrate, the first material layers comprising a sacrificial material and the second material layers comprising an electrically insulating material;

    forming at least one front side opening in the stack;

    forming a charge storage material layer in the at least one front side opening;

    forming a tunnel dielectric over the charge storage material layer in the at least one front side opening;

    forming a semiconductor channel over the tunnel dielectric in the at least one front side opening;

    forming a back side opening in the stack;

    selectively removing the first material layers without removing the second material layers through the back side opening, thereby forming back side recesses between adjacent second material layers, wherein the portions of the charge storage material layer on exposed in the back side recesses;

    selectively oxidizing portions of the charge storage material layer exposed in the back side recesses partially through a thickness of the charge storage material layer to form a cover oxide segments in the charge storage material layer;

    forming a blocking dielectric over a sidewall in the back side opening, over exposed surfaces of the second material layers and over the cover oxide segments in the back side recesses, the blocking dielectric having a clam-shaped portion in the back side recesses; and

    forming a plurality of control gate electrodes, each of the plurality of control gate electrodes is located at least partially in an opening in the respective clam-shaped portion of the blocking dielectric.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×