NAND Memory Block Isolation Structure to Prevent Stack Tilting
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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 forming a memory array with an intervening material between adjacent memory blocks to stabilize the structure.
Innovation Solution
A method involving the formation of a memory array with vertically-stacked memory cells, where an intervening material is introduced between adjacent memory blocks to stabilize the structure, comprising alternating insulative and conductive tiers with bridges extending across trenches between memory blocks, and a vertically-elongated seam in the intervening material to ensure electrical isolation and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory blocks are stacked vertically in NAND architecture, then storage density is improved, but structural stability deteriorates due to block-bending or sideways tilting during fabrication
Solution Approach 1:
The patent divides the memory array into discrete memory blocks separated by trenches, with intervening material filling the trenches. This segmentation provides structural support to each memory block stack independently, preventing sideways tilting while maintaining high vertical stacking for storage density.
Solution Approach 2:
The patent introduces an intermediary material (such as dielectric or sacrificial material) into the trenches between adjacent memory blocks. This intervening material acts as a mediator that provides mechanical support and prevents block-bending, stabilizing the vertically-stacked memory cells during fabrication and operation.
2Stability of the object's composition
If trenches are formed between memory blocks for structural support, then stability is improved, but manufacturing complexity increases due to additional bridge formation and material deposition steps
Solution Approach 1:
The patent performs preliminary actions by forming bridges across trenches and depositing intervening material during the fabrication process before final memory block assembly. This preliminary structuring ensures stability is built-in during manufacturing, avoiding complex post-fabrication adjustments.
Solution Approach 2:
The intervening material in the trenches serves multiple functions: it provides structural support to prevent block-bending, acts as a dielectric for electrical isolation, and can serve as a sacrificial material for subsequent processing steps. This multi-functionality reduces the need for additional dedicated structural components, simplifying the overall device design.
3Strength
If bridges are formed across trenches to support memory blocks, then structural integrity is improved, but device complexity increases due to additional bridging material and process steps
Solution Approach 1:
The patent merges the bridge structure with the intervening material filling the trenches, creating a unified structural element that provides both mechanical support and electrical isolation. This combining of functions reduces the number of separate components and simplifies the device architecture while maintaining structural integrity.
Solution Approach 2:
The patent employs composite material structures where bridges and intervening materials with different properties (conductive, dielectric, sacrificial) are combined in specific configurations. These composite structures provide tailored mechanical and electrical properties needed for memory block stability while optimizing the fabrication process.
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.