3D Memory Stack Backside Support Pillars for Trench Stability
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Solution Overview
Problem
In three-dimensional memory devices, existing technologies face challenges in preventing insulating layers from toppling or leaning into backside trenches during the replacement of sacrificial material layers with word lines and select gate electrodes, which affects the structural integrity and functionality of the memory stacks.
Innovation Solution
The implementation of backside support pillar structures that contact indented sidewalls of alternating stacks, providing structural support and preventing the insulating layers from toppling or leaning into the trenches, while being formed without additional photolithography, deposition, or etching steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If backside support pillar structures are implemented to prevent insulating layers from toppling into trenches, then structural stability is improved, but device complexity increases
Solution Approach 1:
The backside support pillar structures are formed by merging the formation processes of existing structures. The support pillars are created using the same photolithography, deposition, and etching steps that form the word lines and select gate electrodes, eliminating the need for separate processing steps. This combining approach adds structural stability without proportionally increasing device complexity.
Solution Approach 2:
The backside support pillar structures are formed preliminarily before the insulating layers are replaced with word lines and select gate electrodes. This preliminary formation ensures that the support structures are in place to prevent toppling during the subsequent replacement process, addressing the stability issue before it arises.
2Ease of manufacture
If additional photolithography, deposition, or etching steps are avoided in forming support pillar structures, then manufacturing complexity is reduced, but structural support may be insufficient
Solution Approach 1:
The photolithography, deposition, and etching steps serve multiple functions: they form the word lines and select gate electrodes while simultaneously creating the backside support pillar structures. This multi-functionality approach provides adequate structural support without requiring additional manufacturing steps, thus maintaining ease of manufacture while ensuring structural strength.
Data Source
AI summary
At least one vertically alternating sequence of continuous insulating layers and continuous sacrificial material layers is formed over a substrate. Rows of backside support pillar structures are formed through the at least one vertically alternating sequence. Memory stack structures are formed through the at least one vertically alternating sequence. A two-dimensional array of discrete backside trenches is formed through the at least one vertically alternating sequence. Contiguous combinations of a subset of the backside trenches and a subset of the backside support pillar structures divide the at least one vertically alternating sequence into alternating stacks of insulating layers and sacrificial material layers. The sacrificial material layers are replaced with electrically conductive layers while the backside support pillar structures provide structural support to the insulating layers.