Staircase Contact Structures for Stable Vertical Memory Stacks
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Solution Overview
Problem
Conventional vertical memory arrays face issues with stack collapse during processing, leading to reduced reliability due to the height of the stacks increasing for additional memory cells, which is exacerbated by the formation of staircase structures.
Innovation Solution
The implementation of first conductive contact structures with a smaller lateral dimension and larger support pillar structures within the staircase regions to stabilize the stack, reducing the likelihood of collapse during gate replacement processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of the stack is increased to facilitate additional memory cells, then memory density is improved, but the stack becomes prone to toppling or collapse during processing
Solution Approach 1:
The patent divides the stack into multiple tiers with alternating conductive and insulative structures. This segmentation creates a modular architecture where each tier can be independently supported, reducing the risk of complete stack collapse while maintaining high memory density through vertical stacking.
Solution Approach 2:
The patent applies different material properties and structural characteristics to different regions of the stack. Specifically, alternating conductive and insulative tiers provide localized mechanical support and electrical functionality, with insulative tiers offering structural reinforcement at critical points to prevent collapse during processing.
2Ease of operation
If staircase structures are formed at edges of conductive tiers, then electrical access to conductive structures is enabled, but the stack becomes more prone to collapse during gate replacement processing
Solution Approach 1:
The staircase structures are formed with extended lateral dimensions before gate replacement processing occurs. This preliminary structuring creates built-in support features that prevent collapse during subsequent processing steps, allowing electrical access to be established while maintaining stack integrity throughout manufacturing.
Solution Approach 2:
The staircase structures extend the stack's support into the lateral dimension by creating stepped configurations at the edges of conductive tiers. This dimensional extension provides additional surface area for contact structures and creates mechanical reinforcement that prevents vertical collapse during processing.
Data Source
AI summary
A microelectronic device comprises a stack structure comprising insulative structures vertically interleaved with conductive structures, first support pillar structures vertically extending through the stack structure in a first staircase region including steps defined at edges of tiers of the insulative structures and conductive structures, and second support pillar structures vertically extending through the stack structure in a second staircase region including additional steps defined at edges of additional tiers of the insulative structures and conductive structures, the second support pillar structures having a smaller cross-sectional area than the first support pillar structures. Related memory devices, electronic systems, and methods are also described.