Memory Array Trench Insulative Lining for Data Retention
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Solution Overview
Problem
Current memory array fabrication methods face challenges in forming efficient and reliable strings of memory cells, particularly in vertically-stacked NAND architectures, where the integration of conductive and insulative tiers and the formation of charge-blocking regions are critical for maintaining data retention and access control.
Innovation Solution
The method involves forming a stack of alternating insulative and conductive tiers, where channel openings are etched to directly couple channel material with conductor tiers, and subsequent trench formation with insulative lining and core material to create vertically-extending strings of memory cells, including charge-blocking regions and conductive lines, optimizing the structure for improved electrical coupling and data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional memory array fabrication methods are used, then manufacturing process is simpler, but data retention and electrical coupling efficiency deteriorate
Solution Approach 1:
The method forms insulative material linings in trenches before forming core materials and conductive lines. This preliminary action prevents oxide formation at critical interfaces during subsequent processing steps, ensuring reliable electrical coupling and data retention without requiring complex post-processing corrections
Solution Approach 2:
The insulative material lining acts as an intermediary layer between the trench walls and the core material/conductive lines. This intermediary prevents direct contact that would cause oxide formation, while still allowing the structure to function as intended, thereby maintaining reliability without significantly increasing overall device complexity
2Ease of manufacture
If channel material is not directly coupled with conductor tiers, then manufacturing is easier, but electrical coupling efficiency deteriorates
Solution Approach 1:
The method changes the physical and chemical parameters of the trench environment by lining walls with insulative material before forming conductive elements. This parameter change prevents oxide formation at the interface, ensuring direct electrical coupling between channel material and conductor tiers while maintaining manufacturing feasibility through standardized deposition processes
3Ease of manufacture
If oxide formation occurs in trenches, then manufacturing is simpler, but data retention deteriorates
Solution Approach 1:
The method applies preliminary anti-action by forming insulative material linings in trenches before any oxide formation can occur. This preventive measure counteracts the harmful effect of oxide formation that would otherwise degrade data retention, while the lining formation uses standard semiconductor processing techniques that do not significantly complicate manufacturing
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. Horizontally-elongated trenches are formed into the stack to form laterally-spaced memory-block regions. A wall is formed in individual of the trenches laterally-between immediately-laterally-adjacent of the memory-block regions. The forming of the wall comprises lining sides of the trenches with insulative material comprising at least one of an insulative nitride and elemental-form boron. A core material is formed in the trenches to span laterally-between the at least one of the insulative nitride and the elemental-form boron. Structure independent of method is disclosed.