Ultrahigh density vertical nand memory device and method of making thereof
AssigneeSanDisk Technologies LLC
InventorsJohann Alsmeier, George Samachisa
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.
Claims28
A method of making a monolithic three dimensional NAND string, comprising:
- forming a stack of alternating layers of a first layer and a second layer, wherein the first layer comprises a conductive or semiconductor control gate material, and wherein the second layer comprises an insulating sub-layer and a first sacrificial sub-layer;
- etching the stack to form at least one opening in the stack;
- selectively etching the first layer to form first recesses;
- forming a blocking dielectric in the first recesses;
- forming a plurality of discrete charge storage segments separated from each other in the first recesses over the blocking dielectric;
- forming a tunnel dielectric over a side wall of the discrete charge storage segments exposed in the at least one opening;
- forming a semiconductor channel in the at least one opening;
- etching the stack to expose a back side of the stack;
- removing the first sacrificial sub-layer to form second recesses;
- and
- forming a plurality of conductive or semiconductor shielding wings separated from each other in the second recesses;
- wherein the first sacrificial sub-layer is located above or below the insulating sub-layer in each second layer.
A method of making a monolithic three dimensional NAND string, comprising:
- forming a stack of alternating layers of a first layer and a second layer, wherein the first layer comprises a first sacrificial sub-layer, a second sacrificial sub-layer and a third sacrificial sub-layer located between the first sacrificial sub-layer and the second sacrificial sub-layer;
- etching the stack to form at least one opening in the stack;
- selectively etching the third sacrificial sub-layer to form first recesses;
- forming a plurality of discrete charge storage segments separated from each other in the first recesses;
- forming a tunnel dielectric over a side wall of the discrete charge storage segments exposed in the at least one opening;
- forming a semiconductor channel in the at least one opening;
- etching the stack to expose a back side of the stack;
- removing the first sacrificial sub-layer, the second sacrificial sub-layer and the third sacrificial sub-layer to form clam-shaped openings such that the plurality of discrete charge storage segments are exposed in the clam-shaped openings;
- forming a plurality of clam-shaped blocking dielectric segments in the clam-shaped openings over the plurality of discrete charge storage segments;
- and
- forming a plurality of clam-shaped control gate electrodes in the clam-shaped openings over the plurality of the clam-shaped blocking dielectric segments;
- wherein:
- the second layer comprises an insulating layer;
- and
- the third sacrificial sub-layer comprises a sacrificial material different from the first sacrificial sub-layer, the second sacrificial sub-layer, and the second layer.
A method of making a monolithic three dimensional NAND string, comprising:
- forming a stack of alternating layers of a first layer and a second layer over a substrate, wherein the first layer comprises a conductive or semiconductor control gate material and wherein the second layer comprises an insulating material;
- etching the stack to form at least one opening in the stack;
- selectively etching the first layer to form first recesses;
- forming a conductive or semiconductor liner in the first recesses, the conductive or semiconductor liner having a clam shape;
- forming a blocking dielectric over the conductive or semiconductor liner in the first recesses;
- forming a plurality of discrete charge storage segments separated from each other in the first recesses over the blocking dielectric;
- forming a tunnel dielectric over a side wall of the discrete charge storage segments exposed in the at least one opening;
- and
- forming a semiconductor channel in the at least one opening.
Dependencies are inferred from the claim text.