Memory Block Intervening Seam Structure for NAND Stack Stability
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Solution Overview
Problem
The challenge of 'block-bending' or sideways tilting of memory block stacks during fabrication in memory arrays, particularly in NAND architecture, is addressed by incorporating an intervening material with a vertically-elongated seam between adjacent memory blocks to enhance structural integrity and electrical isolation.
Innovation Solution
A method involving the formation of a memory array with vertically-stacked memory cells, where intervening material is introduced between memory blocks, comprising alternating insulative and conductive tiers, with a vertically-elongated seam to provide lateral electrical isolation and prevent shorting, while maintaining structural alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory blocks are placed adjacent to each other without intervening material, then device complexity is reduced, but electrical isolation between blocks is compromised leading to potential short circuits
Solution Approach 1:
An intervening material is introduced between adjacent memory blocks to provide electrical isolation. This intermediary layer prevents direct electrical contact between blocks while maintaining a relatively simple overall structure, resolving the contradiction between reliability and device complexity.
2Quantity of substance
If memory block stacks are made taller to increase capacity, then storage density is improved, but structural stability deteriorates causing block-bending during fabrication
Solution Approach 1:
The structure is segmented by introducing an intervening material layer between memory blocks. This segmentation divides the tall stack into isolated sections that are less prone to bending, allowing increased storage capacity while maintaining structural stability during fabrication.
Solution Approach 2:
A composite structure is formed by combining memory block materials with an intervening isolation material. This composite approach provides both the height needed for increased capacity and the structural support needed to prevent block-bending during fabrication.
3Reliability
If intervening material is added between memory blocks, then electrical isolation is improved, but manufacturing complexity increases
Solution Approach 1:
The intervening material is applied in a controlled, partial manner only where electrical isolation is needed between blocks, rather than throughout the entire structure. This selective application maintains good electrical isolation while minimizing the impact on manufacturing complexity.
Data Source
AI summary
A memory array comprising strings of memory cells comprises laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers. Operative channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. Intervening material is laterally-between and longitudinally-along immediately-laterally-adjacent of the memory blocks. The intervening material comprises longitudinally-alternating first and second regions that individually have a vertically-elongated seam therein. The vertically-elongated seam in the first regions has a higher top than in the second regions. The seam tops in the second regions are elevationally-coincident with or below a bottom of an uppermost of the conductive tiers. Methods are disclosed.