3D Memory Backside Support Pillars for Trench-Side Stack Stability
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Solution Overview
Problem
Existing three-dimensional memory devices face challenges in maintaining structural integrity during the replacement of sacrificial material layers with word lines and select gate electrodes, as insulating layer stacks can topple or lean into backside trenches, leading to potential device failure.
Innovation Solution
The introduction of backside support pillar structures that provide structural support during the replacement process, formed alongside memory stack structures without additional photolithography, deposition, or etching steps, ensuring stability and integrity of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If backside trenches are formed for replacing sacrificial material layers with word lines and select gate electrodes, then the device can achieve functional integration, but the insulating layer stacks become unstable and may topple or lean into the trenches
Solution Approach 1:
The backside support structure is segmented into multiple discrete support pillars distributed across the backside surface. These individual pillars are positioned at strategic locations to provide localized support to the insulating layer stacks, preventing them from toppling into the backside trenches while maintaining the overall functional integration of the device.
Solution Approach 2:
The backside support pillars act as intermediary structures between the insulating layer stacks and the substrate. These pillars provide mechanical support and stabilization to the insulating layer stacks, preventing them from leaning or toppling into the backside trenches during the replacement process of sacrificial material layers with word lines and select gate electrodes.
2Strength
If additional photolithography, deposition, or etching steps are used to form support structures, then structural integrity can be maintained, but the manufacturing process complexity and cost increase
Solution Approach 1:
The formation of backside support pillars is merged with the existing backside trench formation process. The same photolithography and etching steps used to create the backside trenches are also used to define and form the support pillars, eliminating the need for additional processing steps while maintaining structural integrity of the insulating layer stacks.
Solution Approach 2:
The backside support pillars serve multiple functions: they provide structural support to prevent insulating layer stacks from toppling, define the boundaries of backside trenches, and maintain spacing between adjacent memory structures. This multi-functionality is achieved within the existing manufacturing process framework without requiring additional specialized steps.
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.