Memory Controller Read Stress Mitigation via Data Copying
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Solution Overview
Problem
Semiconductor memory devices face reliability issues due to repetitive read operations causing stress on memory cells, leading to errors and reduced operational reliability.
Innovation Solution
A controller system that manages read count values for memory blocks, copies data to a secondary block when a predetermined reference value is reached, and alternates between reading from original and copy data blocks to mitigate read stress and extend the lifespan of memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If read operations are performed repeatedly on the same memory block, then data access speed is maintained, but read stress accumulates causing errors and reduced reliability
Solution Approach 1:
The patent creates a copy of the original memory block when the read count reaches a reference value. Subsequent read operations are directed to the copy block instead of the original, allowing the original to recover from read stress while maintaining fast data access through the copy.
Solution Approach 2:
The patent divides the memory system into original blocks and copy blocks, separating the read stress burden from the original data storage. This segmentation allows independent management of read operations and stress recovery for each block type.
2Reliability
If data is copied to a secondary block to reduce read stress, then reliability is improved, but device complexity increases
Solution Approach 1:
The controller includes a read count manager that continuously monitors the number of read operations on each memory block. When the read count reaches a reference value, the system automatically triggers a copy operation and updates the mapping, providing feedback-based automatic stress management without complex external control.
Solution Approach 2:
The system performs self-service by automatically detecting when copy operations are needed based on read count thresholds and executing the copy and remapping operations autonomously, reducing the need for complex external management mechanisms.
3Reliability
If copy operations are performed frequently to maintain reliability, then read stress is reduced on original blocks, but productivity decreases
Solution Approach 1:
The system performs copy operations preliminarily when the read count reaches a reference value, before errors actually occur in the original block. This proactive approach prevents data degradation while avoiding unnecessary copies, optimizing the balance between reliability and productivity.
Solution Approach 2:
The system dynamically changes the read count reference value parameter based on memory block characteristics and usage patterns. This allows optimization of copy timing to balance reliability improvement with productivity maintenance, performing copies only when necessary rather than at fixed intervals.
Data Source
AI summary
A controller controls a semiconductor memory device including a plurality of memory blocks. The controller may include a controller control unit and a storing unit. The controller control unit compares the number of times of a read of an original memory block among the plurality of memory blocks with a predetermined copy generation reference value, determines whether to generate copy data of original data stored in the original memory block, and generates a command corresponding to the determination. The storage unit stores the copy generation reference value and address information about the original memory block.