Flash Memory Block Retirement Using UECC Error Indicators
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Solution Overview
Problem
Flash memory devices experience data corruption due to mechanisms like program disturb, read disturb, and erase disturb, leading to uncorrectable error correction (UECC) errors, which result in reduced system performance and potential failure, necessitating the retirement of blocks, thereby reducing memory capacity and increasing wear on remaining blocks.
Innovation Solution
Implementing a system for error detection/correction based memory management that performs read operations on memory cells and determines whether to retire defective groups based on an indicator's status, effectively managing block retirement to maintain system performance and capacity while limiting wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blocks are retired when uncorrectable errors occur, then data reliability is improved, but memory capacity is reduced and wear on remaining blocks increases
Solution Approach 1:
The patent applies preliminary action by proactively retiring memory blocks that have experienced a first uncorrectable error before they can cause additional disturbances to neighboring blocks. The controller monitors error status and preemptively retires affected blocks, preventing program disturb and read disturb from propagating to adjacent blocks, thus maintaining overall system reliability while preserving more usable capacity compared to reactive retirement approaches.
2Reliability
If blocks are retired when uncorrectable errors occur, then data reliability is improved, but wear on remaining blocks increases
Solution Approach 1:
The patent applies preliminary action by proactively retiring memory blocks that have experienced a first uncorrectable error before they can cause additional disturbances to neighboring blocks. The controller monitors error status and preemptively retires affected blocks, preventing program disturb and read disturb from propagating to adjacent blocks, thus maintaining overall system reliability while preserving more usable capacity compared to reactive retirement approaches.
3Reliability
If error detection/correction engine is used, then data reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the memory device into multiple independently monitorable blocks with associated error status indicators. Each block can be tracked separately for uncorrectable errors, allowing the error detection/correction engine to operate on segmented units rather than the entire memory space. This modular approach manages complexity by localizing error monitoring and retirement decisions to individual blocks.
Solution Approach 2:
The patent applies feedback through error status indicators that provide real-time information about uncorrectable errors in each memory block. The controller receives feedback from the error detection/correction engine about which blocks have experienced errors and uses this feedback to make informed retirement decisions. This feedback mechanism enables automated error management without requiring complex manual intervention or oversight.
Data Source
AI summary
The present disclosure includes methods, devices, and systems for error detection/correction based memory management. One embodiment includes performing a read operation with respect to a particular group of memory cells of a memory device and, if the read operation results in an uncorrectable error, determining whether to retire the particular group of memory cells in response to a status of an indicator corresponding to the particular group of memory cells, wherein the status of the indicator indicates whether the particular group of memory cells has a previous uncorrectable error associated therewith.