Non-Volatile Memory Block Requalification
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Solution Overview
Problem
Existing memory systems face challenges in efficiently managing and recovering retired blocks of non-volatile memory cells, leading to premature removal of valid blocks and potential system failures.
Innovation Solution
A memory system that executes an error correction mode to recover corrupted data, monitors block status to determine recoverability, and performs a requalification process to restore usable blocks, thereby reducing the retirement of valid blocks and improving system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error correction mode is executed to recover corrupted data, then reliability is improved, but processing time increases
Solution Approach 1:
The patent performs error correction operations and block requalification during idle periods before blocks are definitively retired. By proactively testing and recovering blocks while the system is idle, the system prepares blocks for future use without impacting operational performance when blocks are actually needed.
Solution Approach 2:
The memory system autonomously performs self-diagnosis and self-repair by executing error correction modes and requalification processes on its own blocks without external intervention. The system monitors its own block status and automatically recovers or retires blocks based on their health status.
2Reliability
If blocks are retired prematurely to ensure reliability, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The system continuously monitors block status through error correction operations and uses this feedback to make informed decisions about block retirement. By basing retirement decisions on actual block performance data rather than predetermined thresholds, the system avoids premature retirement of functional blocks.
Solution Approach 2:
The patent dynamically adjusts the criteria for block retirement based on error correction success rates and block performance parameters. Blocks are retired based on their actual measured reliability parameters rather than fixed usage thresholds, allowing functional blocks to remain in use longer.
3Measurement precision
If comprehensive block monitoring is performed, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The memory system performs self-monitoring through built-in error correction operations and status monitoring mechanisms. Each block is tested using standard read/write operations and error correction codes that are inherently part of the memory system's normal operation, eliminating the need for separate external monitoring equipment.
Data Source
AI summary
Methods, systems, and devices for sorting retired blocks of non-volatile memory cells are described. A memory system may recover a block that has been marked as “bad” using a requalification process. For example, after operating in an error protection mode for the block, the memory system may monitor the block to determine whether a status flag indicating an access error is set. If the status flag is set, the memory system may store information that indicates the block is unrecoverable, and the block may subsequently be retired. Alternatively, if a status flag is not set, the memory system may store information that indicates the block may be recoverable. If one or more additional access operations to the block are successful, the memory system may store information that indicates the block may be used for subsequent access operations.