Ultrahigh density vertical nand memory device and method of making thereof
AssigneeSanDisk Technologies LLC
InventorJohann Alsmeier
Life of this patent
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Abstract
Monolithic, three dimensional NAND strings include a semiconductor channel, at least one end portion of the semiconductor channel extending substantially perpendicular to a major surface of a substrate, a plurality of control gate electrodes having a strip shape extending substantially parallel to the major surface of the substrate, the blocking dielectric comprising a plurality of blocking dielectric segments, a plurality of discrete charge storage segments, and a tunnel dielectric located between each one of the plurality of the discrete charge storage segments and the semiconductor channel.
Claims19
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 over a substrate, wherein the first material comprises a conductive or semiconductor control gate material and wherein the second material comprises a sacrificial material which can be selectively etched compared to the first material;
- etching the stack to form at least one opening in the stack;
- forming a blocking dielectric layer on a side wall of the at least one opening;
- forming a discrete charge storage material layer on the blocking dielectric layer in the at least one opening;
- forming a tunnel dielectric layer on the discrete charge storage material layer in the at least one opening;
- forming a semiconductor channel layer on the tunnel dielectric layer in the at least one opening;
- removing the second material to expose the blocking dielectric layer between the first material layers;
- etching the blocking dielectric layer and the discrete charge storage material layer using the first material layers as a mask to form a plurality of separate discrete charge storage segments and blocking dielectric segments;
- and
- depositing an insulating material between the first material layers, between the blocking dielectric segments and between the discrete charge storage segments.
A monolithic three dimensional NAND string, comprising:
- a semiconductor channel located over a substrate, at least one end of the semiconductor channel extending substantially perpendicular to a major surface of the substrate;
- a plurality of control gate electrodes having a strip shape extending substantially parallel to the major surface of the substrate, wherein the plurality of control gate electrodes comprise at least a first control gate electrode located in a first device level and a second control gate electrode located in a second device level located over the substrate and below the first device level;
- and
- a plurality of discrete charge storage segments, wherein the plurality of discrete charge storage segments comprise at least a first discrete charge storage segment located in the first device level and a second discrete charge storage segment located in the second device level;
- a blocking dielectric located between the plurality of discrete charge storage segments and the plurality of control gate electrodes;
- and
- a tunneling dielectric located between the plurality of discrete charge storage segments and the semiconductor channel;
- wherein:
- the blocking dielectric comprising a plurality of blocking dielectric segments;
- each of the plurality of the blocking dielectric segments is located in contact with a respective one of the plurality of control gate electrodes;
- at least a portion of each of the blocking dielectric segments has a clam shape;
- and
- each of the plurality of control gate electrodes is located at least partially in an opening in the clam-shaped portion of a respective blocking dielectric segment.
Dependencies are inferred from the claim text.