3D NAND Memory Block Pillars to Prevent Block Bending
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Solution Overview
Problem
The technical challenge lies in preventing 'block-bending' or the tilting of memory blocks during fabrication in memory arrays, which can lead to structural instability and fabrication errors in memory arrays, particularly in NAND architecture.
Innovation Solution
The method involves forming a memory array with vertically-alternating insulative and conductive tiers, where pillars are created laterally-between memory blocks to provide lateral electrical isolation and structural support, with these pillars being wider at their bottoms than at their tops to maintain stability and prevent tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If memory blocks are formed without lateral support structures, then fabrication process is simpler, but block-bending or tilting occurs during fabrication
Solution Approach 1:
Pillars are introduced as intermediary structures between memory blocks to provide lateral support and prevent tilting. These pillars act as mediators that transfer mechanical support from the substrate to the memory blocks, eliminating the need for complex fabrication processes while ensuring structural stability.
Solution Approach 2:
The memory array structure combines different materials with complementary properties: insulative materials for electrical isolation, conductive materials for signal transmission, and structural materials for mechanical support. This composite approach allows simultaneous achievement of fabrication simplicity and structural stability.
2Ease of manufacture
If pillars are formed with uniform width, then fabrication is easier, but structural stability and anti-tilting performance deteriorates
Solution Approach 1:
Pillars are designed with asymmetric cross-sections, being wider at the bottom than at the top. This asymmetric geometry provides enhanced structural strength and anti-tilting performance at the base where support is most critical, while maintaining relatively simple fabrication processes through standard deposition and etching techniques.
Solution Approach 2:
The pillar structure implements local quality by varying the width along its height - wider at the bottom for maximum structural support and narrower at the top to reduce material usage and accommodate adjacent structures. This localized variation optimizes both structural strength and fabrication efficiency.
Data Source
AI summary
A method used in forming a memory array comprising strings of memory cells comprises forming a stack comprising vertically-alternating first tiers and second tiers. Intervening material is formed into the stack laterally-between and longitudinally-along immediately-laterally-adjacent memory block regions. The forming of the intervening material comprises forming pillars laterally-between and longitudinally-spaced-along the immediately-laterally-adjacent memory-block regions. The pillars individually extend through multiple of each of the first tiers and the second tiers. After forming the pillars, an intervening opening is formed individually alongside and between immediately-longitudinally-adjacent of the pillars. Fill material is formed in the intervening openings. Other embodiments, including structure, are disclosed.