Memory Wordline Grouping for Error Compensation
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Solution Overview
Problem
Memory devices face challenges in accurately reading cells due to physical phenomena like cell-to-cell coupling and lateral migration, which cause threshold voltage shifts and impair error handling and compensation.
Innovation Solution
The proposed solution involves grouping wordlines based on the sensitivity of victim cells to aggressor cell programming levels, allowing for tailored compensatory operations to mitigate the effects of cell-to-cell coupling and lateral migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error compensation operations are performed on all memory cells, then bit error rate is reduced, but resource consumption and processing time increase
Solution Approach 1:
The patent applies different error compensation strategies to different wordlines based on their specific sensitivity characteristics. Wordlines are classified into first and second groups according to their aggregate sensitivity measures, with the first group receiving full error compensation operations and the second group receiving reduced or no compensation operations. This localized approach ensures that resources are concentrated on the wordlines that most need them, rather than uniformly applying compensation to all wordlines.
2Reliability
If error compensation operations are performed on all memory cells, then bit error rate is reduced, but resource consumption increases
Solution Approach 1:
The patent implements selective error compensation by classifying wordlines into different groups based on their aggregate sensitivity measures. The first group of wordlines with higher sensitivity receives comprehensive error compensation operations including multiple read attempts and voltage adjustments, while the second group with lower sensitivity receives minimal or no compensation operations. This localized quality approach optimizes resource allocation by directing computational and energy resources only to the wordlines that exhibit higher error susceptibility.
3Productivity
If sensitivity-based wordline grouping is implemented, then error handling efficiency is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary characterization of wordline sensitivity during manufacturing or initial operation, calculating aggregate sensitivity measures for each wordline before normal operation begins. These sensitivity characteristics are stored and used to pre-classify wordlines into different groups. This preliminary action allows the system to be optimized for error handling efficiency without adding complexity to the real-time operation, as the classification decisions are made in advance rather than dynamically during each read operation.
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
This approach enhances the efficiency of error handling by reducing resource and time consumption, improving the reliability of memory devices by minimizing bit errors and error rates.
Implementation Method 1
physical phenomena like cell-to-cell coupling and lateral migration, which cause threshold voltage shifts
Implementation Method 2
physical phenomena like cell-to-cell coupling and lateral migration, which cause threshold voltage shifts
Data Source
AI summary
A system comprising a memory device comprising a plurality of memory cells and a processing device, operatively coupled with the memory device, to perform operations. The processing device determines, for each memory cell of the plurality of memory cells, a respective value of a metric that reflects a sensitivity of a threshold voltage of the memory cell to a change in an adjacent memory cell. The processing device determines, for each wordline of a plurality of wordlines of the memory device, based on the determined values of the metric, a respective aggregate measure of adjacent cell dependence. The processing device categorizes the wordlines into one or more wordline groups based on comparing, for each wordline, the determined aggregate measure of adjacent cell dependence to at least one threshold dependence value.