Non-volatile Memory Cells Programmed by Edge Distance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As memory structures increase in density, maintaining data integrity becomes challenging due to errors in programming non-volatile memory cells, particularly in three-dimensional memory systems where cells are programmed to different final targets based on their distance to word line layers.
Innovation Solution
A control circuit configures memory cells at different distances from word line edges to distinct target voltage levels, ensuring that cells closer to edges are programmed to a higher threshold voltage distribution and those further away to a lower distribution, using a method that adjusts verify reference voltages for each group based on their distance from the edge, thereby minimizing programming speed variations and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory structures increase in density to improve storage capacity, then storage capacity is improved, but programming errors increase and data integrity deteriorates
Solution Approach 1:
The patent applies local quality by programming memory cells to different final target threshold voltage distributions based on their specific location (distance from word line edges). Memory cells are divided into groups according to their distance from isolation areas, and each group is programmed to a distinct target voltage level. This localized programming approach accounts for position-dependent programming speed variations, thereby maintaining data integrity while achieving high-density storage.
2Reliability
If memory cells are programmed to different final targets based on distance to word line layers to reduce programming errors, then data integrity is improved, but device complexity increases
Solution Approach 1:
The patent implements segmentation by dividing memory cells into distinct groups based on their distance from word line edges and isolation areas. Each group is assigned a specific final target threshold voltage distribution. This segmentation strategy simplifies the programming control by creating discrete, manageable categories of memory cells that can be programmed independently, reducing the overall complexity compared to continuous adjustment approaches.
Solution Approach 2:
The patent changes the programming parameter (final target threshold voltage) based on the spatial parameter (distance from word line edges). By establishing a correspondence between physical location and programming target voltage, the system automatically adjusts programming parameters according to position, reducing programming errors without requiring complex real-time monitoring and adjustment mechanisms.
3Manufacturing precision
If verify reference voltages are adjusted for each group of memory cells to minimize programming speed variations, then programming precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the grouping of memory cells based on their distance from word line edges and pre-determining the appropriate verify reference voltages for each group. This preliminary classification and voltage assignment is done during the programming process setup, allowing for precise programming without requiring complex real-time voltage adjustment mechanisms during actual manufacturing, thereby improving programming precision while managing manufacturing complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A memory system is configured to program different memory cells to different final targets for a common data state based on distance to one or more edges of a word line layer.