Segmented Charge-Storage Channels for NAND Data Retention
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Solution Overview
Problem
Conventional NAND memory architectures face data retention issues due to charge migration between memory cells caused by charge-trapping material extending across multiple cells, leading to inefficiencies in charge storage and retrieval.
Innovation Solution
Incorporating breaks in the charge-trapping material between memory cells and using a vertical stack of alternating insulative and conductive levels with high-k dielectric material, charge-blocking material, and vertically-spaced charge-storage segments to impede charge migration and enhance data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charge-trapping material is used to store charge in NAND memory cells, then charge storage capability is improved, but charge migration between adjacent memory cells occurs causing data retention issues
Solution Approach 1:
The charge-blocking material is divided into multiple vertically-spaced segments that are positioned between adjacent memory cell strings. These segmented barriers create isolated charge storage regions, preventing charge migration between cells while maintaining storage capability within each cell. The segmentation approach directly addresses the charge migration problem by creating discrete blocking regions rather than continuous barriers.
Solution Approach 2:
Charge-blocking material segments are introduced as intermediary structures between the charge-trapping material of adjacent memory cells. These intermediary segments act as mediators that prevent direct charge migration between cells while allowing each cell to maintain its charge storage function. The segments are positioned in the spaces between cell strings and extend vertically to block charge movement.
2Quantity of substance
If vertically-stacked memory cell architecture is implemented to increase storage density, then storage capacity is improved, but charge migration between adjacent cells increases leading to data retention problems
Solution Approach 1:
In the vertically-stacked architecture, charge-blocking segments are placed between adjacent cell strings at multiple vertical levels. This segmentation creates isolated charge storage regions throughout the vertical stack, preventing charge migration between neighboring cells while maintaining the high-density stacked configuration. The segments are positioned to block charge movement in the vertical direction between cells.
Solution Approach 2:
The charge-blocking segments are strategically positioned only in specific locations between adjacent cell strings where charge migration is most problematic. The segments have localized presence rather than continuous coverage, allowing charge storage in memory cells while providing targeted blocking where needed. This local quality approach maintains storage density while addressing migration issues at critical interfaces.
3Ease of manufacture
If continuous charge-trapping material is used across multiple memory cells, then manufacturing simplicity is maintained, but charge migration between cells occurs reducing data retention
Solution Approach 1:
The charge-blocking material is formed as discrete vertically-spaced segments rather than continuous structures. These segments can be manufactured using standard deposition and etching processes, where the material is deposited and then patterned into segments through selective removal. This segmentation approach maintains compatibility with existing manufacturing processes while preventing charge migration.
Solution Approach 2:
Portions of the charge-blocking material are selectively removed to create gaps between segments. This extraction approach transforms a potentially continuous structure into segmented barriers that prevent charge migration. The material is taken out in specific regions to create the blocking segments, maintaining manufacturing simplicity while achieving the desired charge isolation function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces charge migration, improving data retention and operational characteristics of NAND memory cells by creating distinct segments that prevent unwanted charge transfer between cells, thereby enhancing the reliability and efficiency of charge storage.
Implementation Method 1
high-k dielectric material arranged in vertically-spaced linear segments
Implementation Method 2
charge-blocking material arranged in vertically-spaced linear segments adjacent the high-k dielectric material
Data Source
AI summary
Some embodiments include a NAND memory array having a vertical stack of alternating insulative levels and conductive levels. The conductive levels include control gate regions. High-k dielectric material is adjacent to the control gate regions and is configured as an arrangement of first vertically-extending linear segments which are vertically spaced from one another. Charge-blocking material is adjacent to the high-k dielectric material and is configured as an arrangement of second vertically-extending linear segments which are vertically spaced from one another. Charge-storage material is adjacent to the charge-blocking material and is configured as an arrangement of third vertically-extending linear segments which are vertically spaced from one another. Gate-dielectric material is adjacent to the charge-storage material. Channel material extends vertically along the stack and is adjacent to the gate-dielectric material. Some embodiments include integrated assemblies and methods of forming integrated assemblies.