Adaptive Read Trim for Memory Data Retention
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Solution Overview
Problem
Increasing storage density in non-volatile memories, such as flash memory devices, leads to higher susceptibility to storage and reading errors, necessitating a solution to reduce bit error rates, particularly in first read scenarios.
Innovation Solution
Implementing adaptive read trim values and read refresh operations to maintain memory cells in a second read state, adjusting read conditions based on the life cycle of the cells to minimize errors and preserve data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage density is increased in non-volatile memories, then storage capacity is improved, but bit error rate increases
Solution Approach 1:
The patent applies dynamics by making the read trim value adjustable and adaptive rather than fixed. The read trim value is dynamically modified based on the life cycle stage of the memory block, allowing the system to adapt read conditions to changing characteristics of high-density memory cells as they age, thereby maintaining reliability despite increased storage density
Solution Approach 2:
The patent implements parameter changes by modifying the read trim value parameter based on erase cycle counts. As memory blocks progress through their life cycle (increasing erase cycles), the read trim parameter is adjusted to compensate for degradation effects, directly addressing the increased bit error rate in high-density storage while preserving the high storage capacity
2Reliability
If read trim value is adjusted for end-of-life blocks, then data retention is improved, but read performance in beginning-of-life blocks may deteriorate
Solution Approach 1:
The system dynamically selects different read trim values based on the life cycle stage of memory blocks. Beginning-of-life blocks use optimized read trim values for maximum read performance, while end-of-life blocks use adjusted read trim values to maintain data retention, thus avoiding performance deterioration in young blocks while improving reliability in aged blocks
Solution Approach 2:
The patent applies local quality by treating different life cycle stages of memory blocks differently. Instead of using a uniform read trim value for all blocks, the system applies specific read trim adjustments tailored to the particular stage (beginning-of-life, middle-of-life, end-of-life) of each block, optimizing both performance and retention for each group
Data Source
AI summary
A data storage system performs operations including determining an endurance level of a block of memory cells; adjusting a read performance profile for the block of memory cells based on the determined endurance level; receiving a data read command specifying data to be read from a particular memory cell of the block of memory cells; and in response to the data read command, performing a read operation on the particular memory cell using the adjusted read performance profile.