Multi-division 3d nand memory device
AssigneeYangtze Memory Technologies Co., Ltd.
InventorsZhong ZHANG, Yan Ni LI
Life of this patent
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Abstract
Disclosed is a method for forming a staircase structure of 3D memory. The method includes providing a substrate, forming an alternating layer stack over the substrate, forming a plurality of block regions over a surface of the alternating layer stack, forming a first plurality of staircase structures to expose a portion of a first number of top-most layer stacks at each of the block regions and removing the first number of the layer stacks at a second plurality of staircase structures at each of the block regions.
Claims20
A semiconductor structure, comprising:
- a substrate;
- a first plurality of layer stacks disposed over the substrate, wherein the first plurality of layer stacks has a first number of layer stacks;
- a second plurality of layer stack disposed over the first plurality of layer stack, wherein the second plurality of layer stacks has the first number of layer stacks;
- a first staircase structure disposed over the substrate, wherein a step of the first staircase structure exposes a portion of a layer stack of the first plurality of layer stacks, the first staircase structure comprising:
- a second number of steps in a first horizontal direction;
- and
- a third number of steps in a second horizontal direction;
- and
- a second staircase structure horizontally abutting the first staircase structure, wherein a step of the second staircase structure exposes a portion of a layer stack of the second plurality of layer stacks.
A method for forming a semiconductor structure, comprising:
- forming a plurality of layer stacks over a substrate;
- forming a first plurality of staircase structures, wherein a step of each staircase structure exposes a portion of a layer stack of the plurality of layer stacks, the formation of the first plurality of staircase structures comprising:
- removing a portion of one or more top layer stacks in the plurality of layer stacks using a first mask stack;
- trimming the first mask stack;
- and
- repeating the removing and trimming operations to form a first number of steps in a first horizontal direction for each staircase structure;
- forming a second mask stack to cover a second plurality and expose a third plurality of staircase structures from the first plurality of staircase structures, wherein each of the second plurality of staircase structures is adjacent to a respective staircase structure from the third plurality of staircase structures;
- and
- removing a second number of layer stacks of the plurality of layer stacks using the second mask stack.
A memory device, comprising:
- a substrate;
- a first plurality of layer stacks disposed over the substrate;
- a second plurality of layer stacks disposed over the first plurality of the layer stacks;
- a vertical memory string extending through the first and the second plurality of layer stacks;
- and
- a first and a second staircase structure disposed adjacent to the vertical memory string, wherein the first staircase structure exposes a portion of each layer stack of the first plurality of layer stack, and the second staircase structure exposes a portion of each stack of the second plurality of layer stacks, wherein the first staircase structure horizontally abuts the second staircase structure, each of the first and the second staircase structure comprising:
- a first number of steps in a first horizontal direction;
- and
- a second number of steps in a second horizontal direction.
Dependencies are inferred from the claim text.