Three-dimensional memory device including capped hollow tube-shaped drain regions and methods of making the same
AssigneeSanDisk Technologies LLC
InventorKeita YAMAMOTO
Life of this patent
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Abstract
A semiconductor structure includes an alternating stack of insulating layers and electrically conductive layers, a memory opening vertically extending through the alternating stack, and a memory opening fill structure located in the memory opening and including a memory film, a vertical semiconductor channel, a dielectric core laterally surrounded by the vertical semiconductor channel, and a drain region overlying the dielectric core and the vertical semiconductor channel. The drain region includes an end cap portion and a hollow tubular portion vertically protruding downward from the end cap portion and laterally surrounding a top tip portion of the dielectric core.
Claims20
A semiconductor structure comprising:
- an alternating stack of insulating layers and electrically conductive layers;
- a memory opening vertically extending through the alternating stack;
- and
- a memory opening fill structure located in the memory opening and comprising a memory film, a vertical semiconductor channel, a dielectric core laterally surrounded by the vertical semiconductor channel, and a drain region overlying the dielectric core and the vertical semiconductor channel, wherein the drain region comprises an end cap portion and a hollow tubular portion vertically protruding downward from the end cap portion and laterally surrounding a top tip portion of the dielectric core.
A method of forming a semiconductor structure, comprising:
- forming an alternating stack of insulating layers and spacer material layers over a substrate, wherein the spacer material layers are formed as or are subsequently replaced with electrically conductive layers;
- forming a memory opening through the alternating stack;
- forming a memory film in the memory opening;
- forming a semiconductor channel material layer over the memory film;
- forming a sacrificial cover layer comprising a sacrificial cover material over the semiconductor channel material layer;
- converting a top portion of the sacrificial cover layer into an etch mask material portion without changing a material composition of a lower portion of the sacrificial cover layer;
- removing the lower portion of the sacrificial cover layer selective to the etch mask material portion and the semiconductor channel material layer;
- forming a dielectric core within a cavity that is laterally surrounded by the vertical semiconductor channel;
- forming a drain cavity by removing the etch mask material portion selective to the dielectric core and the semiconductor channel material layer;
- and
- forming a drain region in the drain cavity.
Dependencies are inferred from the claim text.