Flash Memory Data Renewal for Reliability
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Solution Overview
Problem
Modern flash memory technologies face reliability issues due to increased error rates and data integrity problems, particularly with data retention and endurance, exacerbated by miniaturization, leading to frequent corruption and reduced storage lifespan, especially for infrequently accessed data.
Innovation Solution
A method for regularly testing and renewing data in flash memory units protected by ECC, where test-reading cycles are activated based on predefined parameters such as usage patterns and ECC error thresholds, with data being transferred to fresh memory pages when errors exceed predetermined limits, allowing for proactive correction and renewal of critical states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If miniaturization is increased to accommodate more information on the same chip area, then storage capacity is improved, but reliability deteriorates due to increased error rates and reduced data retention
Solution Approach 1:
The patent implements preliminary action by periodically testing memory units before errors occur and proactively renewing data in memory units that show signs of degradation. The system monitors ECC error counts and initiates data renewal operations in advance, before the errors accumulate to a critical level that would compromise data integrity.
Solution Approach 2:
The patent employs feedback mechanisms by continuously monitoring ECC error counts in memory units and using this information to dynamically adjust data renewal strategies. The system feeds back error statistics to the memory management unit, which then determines which memory units require renewal and at what frequency, creating a closed-loop reliability management system.
2Reliability
If data is accessed frequently to ensure reliability, then data integrity is improved, but adjacent cells become corrupted due to read and program disturb effects
Solution Approach 1:
The patent extracts the problematic data from memory units showing high error rates and relocates it to fresh memory units. By separating the corrupted data from its original location and transferring it to clean memory spaces, the system eliminates the harmful disturb effects that would otherwise affect adjacent cells during repeated access operations.
Solution Approach 2:
The system performs preliminary data renewal operations on memory units before they accumulate sufficient errors to cause widespread disturb effects. By proactively moving data from memory units showing early signs of degradation, the system prevents the accumulation of errors that would otherwise propagate to adjacent cells through repeated read and write operations.
3Reliability
If data renewal operations are performed frequently to maintain reliability, then data integrity is improved, but device complexity and operational overhead increase
Solution Approach 1:
The patent applies local quality by differentiating between memory units based on their error characteristics. Instead of uniformly renewing all data, the system identifies and targets only those memory units showing elevated ECC error counts. This selective approach maintains reliability where needed while avoiding unnecessary renewal operations in healthy memory units, thereby reducing overall system complexity.
Solution Approach 2:
The patent implements partial action by performing data renewal operations only on memory units that require it, rather than systematically renewing all memory units. The system uses ECC error statistics to determine the exact scope of renewal operations, applying renewal only to the extent necessary to maintain reliability, thus avoiding excessive operational overhead.
4Reliability
If strict programming rules are followed to minimize program disturb effects, then reliability is improved, but productivity decreases due to limited programming flexibility
Solution Approach 1:
The patent performs preliminary data renewal operations before strict programming rules would be violated. By proactively moving data from degrading memory units to fresh units, the system creates head space and prepares clean memory regions in advance, allowing subsequent programming operations to proceed efficiently without needing to adhere to rigid sequential programming constraints.
Data Source
AI summary
A method renews data in a flash memory which is organized in memory units and whose memory units which have been written to are error-protected using ECC words. The memory units which have been written to are test-read in regularly activated test-reading cycles, and either individual memory units which have been written to or all memory units which have been written to are renewed on the basis of the ECC error states which have occurred in a test-reading cycle.