Memory Sub-System Die-Level Parameter Optimization
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Solution Overview
Problem
Existing memory sub-systems face challenges in maintaining optimal memory access operation parameters, such as threshold voltage, due to die-to-die variability and shifting voltage distributions, leading to reliability and error rate issues.
Innovation Solution
A memory sub-system that determines optimal threshold voltage and other parameters for each die by performing tests with various parameter values, measuring fail bit count distributions, and setting the optimal values to minimize error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory access operation parameters are optimized for each die individually, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent divides the memory system into individual die units, each with its own optimized parameter set. Instead of treating the entire memory array uniformly, the system segments parameter optimization at the die level, allowing each die to have customized threshold voltage and other access parameters based on its specific characteristics and fail bit count distribution.
Solution Approach 2:
The patent applies local quality by tailoring memory access operation parameters specifically to each die's characteristics. Each die receives customized parameter values (such as threshold voltage) determined by its own fail bit count distribution, rather than applying a uniform parameter set across all dies. This localized parameter optimization improves reliability by accounting for die-to-die variability.
2Productivity
If threshold voltage distribution is shifted to optimize performance, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent deliberately changes the threshold voltage parameter by shifting the threshold voltage distribution. This parameter change allows the system to optimize memory access performance and reduce fail bit counts by adjusting the threshold voltage to better align with the actual voltage distribution in the memory cells, rather than relying on fixed manufacturing specifications.
Data Source
AI summary
A predefined data pattern is written using a plurality of values of a memory access parameter. A corresponding value of a data state metric associated with each value of a plurality of values of the memory access operation parameter is measured. An optimal value of the memory access operation parameter is selected from the plurality of values of the memory access operation parameter.