Non-Volatile Memory Read Disturbance Mitigation via Selective Reprogramming
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Solution Overview
Problem
Non-volatile memory devices, such as flash memory, suffer from read disturbances that cause data unreliability after multiple read operations, especially in areas that have experienced many erase/program cycles, leading to increased bit-error-rates and data retention issues.
Innovation Solution
The implementation of selective reprogramming techniques that involve accessing threshold values associated with data areas, tracking read operations and elapsed time since the last programming, and selectively reprogramming data when these values exceed predetermined thresholds to mitigate read disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple read operations are performed on non-volatile memory data areas, then data can be accessed and retrieved, but read disturbances cause data unreliability and increased bit-error-rates
Solution Approach 1:
The system performs preliminary reprogramming operations on data areas before read disturbances accumulate to unacceptable levels. By monitoring read operation counts and elapsed times, the system proactively repromises data when thresholds are approached, preventing read disturbances from causing permanent data corruption rather than reacting after errors occur.
Solution Approach 2:
The system continuously monitors read operation counts and elapsed time since last programming, using this feedback to dynamically determine when reprogramming is necessary. The monitoring mechanism provides real-time information about data area conditions, enabling the system to adjust reprogramming timing based on actual usage patterns and disturbance accumulation rates.
2Reliability
If reprogramming operations are performed frequently to mitigate read disturbances, then data integrity is maintained, but device wear increases and productivity decreases
Solution Approach 1:
The system dynamically adjusts reprogramming frequency and timing based on monitored conditions rather than using fixed schedules. By adapting reprogramming operations to actual data area conditions (read counts, elapsed time, wear levels), the system performs reprogramming only when necessary, avoiding unnecessary operations that would waste productivity while maintaining data integrity.
Solution Approach 2:
The system changes operational parameters (reprogramming timing, frequency, and scope) based on monitored data area conditions. By adjusting these parameters dynamically according to read operation patterns and wear accumulation, the system optimizes the balance between maintaining data integrity and preserving operational efficiency.
3Ease of manufacture
If reprogramming is performed based on fixed thresholds, then implementation is simple, but it cannot adapt to varying wear patterns and read operation intensities
Solution Approach 1:
The system transitions from static fixed thresholds to dynamic adaptive thresholds that evolve based on monitored data area conditions. The reprogramming decision criteria dynamically adjust according to actual wear patterns, read operation intensities, and elapsed times, enabling the system to adapt to varying usage patterns while maintaining a relatively simple implementation framework.
Data Source
AI summary
The present disclosure includes systems and techniques relating to non-volatile memory. A described device includes a non-volatile memory structure including a first data area, and a second data area that stores information. The information can include a first value corresponding to the first data area, the first value being set responsive to a last programming cycle on the first data area, and a second value indicating a total number of programming or erasing operations on the first data area.