Flash Memory ECC Majority Voting for Uncorrectable Read Errors
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Solution Overview
Problem
Existing Flash memory technologies, particularly Multiple Level Cell (MLC) Flash memories, face challenges in balancing operation performance and system resource management, leading to uncorrectable errors that current solutions fail to adequately address.
Innovation Solution
A method involving a controller that performs majority vote on data read at different times to generate majority vote data, checking for uncorrectable errors, and determining whether to output this data, thereby reducing uncorrectable errors in error correction code (ECC) for Flash memory devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MLC Flash memories are used to increase storage density, then storage capacity is improved, but error rate increases due to unstable characteristics
Solution Approach 1:
The patent applies preliminary action by performing multiple reads at different times before final data output. The controller reads data at least twice at different times, performs majority vote to generate corrected data, and only outputs data after verification. This preliminary corrective action prevents uncorrectable errors from affecting storage capacity while maintaining high density MLC Flash memory operation.
Solution Approach 2:
The patent implements feedback through the majority vote mechanism where the controller compares multiple read results and uses the feedback from these comparisons to determine the final output data. The ECC decoding result is fed back to verify data integrity before output, creating a feedback loop that reduces error rate while maintaining the high storage density of MLC Flash memories.
2Reliability
If multiple reads at different times are performed to reduce errors, then reliability is improved, but operation time increases
Solution Approach 1:
The patent applies partial action by performing majority vote only when necessary - specifically when uncorrectable errors are detected during ECC decoding. The controller reads data at least twice and performs majority vote to generate corrected data, but this excessive reading and processing is activated only when error conditions occur, rather than always. This selective application reduces the time penalty while maintaining high reliability for error-prone MLC Flash memory operations.
3Reliability
If error correction checking is performed on every read operation, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service by having the controller automatically perform majority vote and ECC verification without external intervention. The controller reads data at least twice, performs majority vote to generate corrected data, and automatically determines whether to output the corrected data based on error detection. This self-service error correction mechanism improves reliability while keeping the complexity manageable by using straightforward automated procedures rather than complex external verification systems.
Data Source
AI summary
A method for reducing uncorrectable errors of a memory device regarding Error Correction Code (ECC) includes: performing majority vote according to data read at different times at a same address in order to generate majority vote data corresponding to the address; and checking whether the majority vote data has any uncorrectable error in order to determine whether to output the majority vote data as data of the address. An associated memory device and the controller thereof are further provided.