Memory Cell Segmentation for Coupling Compensation
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Solution Overview
Problem
Memory devices face challenges in accurately reading cells due to cell-to-cell coupling and lateral migration, which cause shifts in threshold voltages, leading to errors and reduced reliability, requiring resource-intensive compensation methods that increase data transfer latency.
Innovation Solution
The approach involves segmenting wordlines into groups to achieve a sufficient read window budget increase without resorting to perfect compensation, by determining target adjustments based on voltage values and aggregating RWB increases across wordline groups, thereby reducing the need for extensive parameter modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perfect compensation methods are used to mitigate cell-to-cell coupling and lateral migration effects, then bit error rate improves, but data transfer latency and resource consumption increase
Solution Approach 1:
The patent applies partial compensation by determining target adjustments to parameters (such as read reference voltages or programming voltages) based on aggregated RWB increases across wordline groups, rather than implementing perfect compensation for each individual cell. This partial action achieves sufficient error mitigation while avoiding the excessive resource consumption and latency associated with perfect compensation methods
2Manufacturing precision
If perfect compensation is applied to each wordline, then read window budget increase is maximized, but resource intensity and processing time increase
Solution Approach 1:
The patent merges adjacent wordlines into wordline groups and aggregates the RWB increases across these groups to determine target parameter adjustments. This merging approach maintains sufficient read window budget while reducing the computational resources and processing time required compared to evaluating each wordline individually
Solution Approach 2:
The patent determines target adjustments that achieve sufficient (but not maximum) RWB gain across wordline groups. This partial action approach avoids the excessive resource intensity of pursuing maximum compensation while still achieving acceptable read window budgets for reliable operation
3Measurement precision
If extensive parameter modifications are performed for compensation, then threshold voltage accuracy improves, but processing complexity and time increase
Solution Approach 1:
The patent segments the memory device into multiple wordline groups and processes these groups independently to determine target parameter adjustments. This segmentation reduces processing complexity by breaking down the overall compensation task into manageable segments, while still achieving sufficient threshold voltage accuracy through aggregated RWB increases
Solution Approach 2:
The patent performs partial parameter modifications based on aggregated RWB increases rather than extensive individual adjustments. This approach achieves sufficient threshold voltage accuracy while avoiding the excessive processing complexity and time associated with comprehensive parameter optimization
Data Source
AI summary
Embodiments disclosed can include determining, for a wordline of the plurality of wordlines, a target read window budget (RWB) increase, wherein the target RWB increase corresponds to a maximum RWB increase associated with using a different PV voltage offset for each respective programming level of a memory cell. Embodiments can also include segmenting the plurality of wordlines into one or more wordline groups, wherein each wordline group comprises one or more wordlines. Embodiments can further include determining, for each wordline group, a target adjustment to a parameter of a memory access operation that is performed with respect to a memory cell associated with a wordline of the wordline group. Embodiments can include determining an aggregate RWB increase for the block in view of the target adjustment to the parameter of the memory access operation. Embodiments can further include determining that the aggregate RWB increase for the block satisfies a threshold range associated with the target RWB increase. Embodiments can also include modifying the parameter of the memory access operation according to the target adjustment.