Non-Volatile Memory Buffer Reliability via Read Disturbance Compensation
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Solution Overview
Problem
Non-volatile memory devices face reliability issues due to read disturbances that cause threshold voltage distributions to shift or broaden, affecting the accuracy of data storage and retrieval, particularly in buffer memory cells using the on-chip buffered programming method.
Innovation Solution
A method is introduced to operate non-volatile memory devices by selecting sample buffer memory cells, measuring their reliability through error counting or threshold voltage ratio analysis, and determining whether error correction is necessary based on predefined threshold values, thereby ensuring accurate data transfer from buffer to main memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If read operations are repeatedly performed on programmed blocks, then data access is enabled, but threshold voltage distribution of erased blocks shifts or broadens due to read disturbance
Solution Approach 1:
The patent applies preliminary action by performing a read disturbance compensation operation before the actual read operation. This compensation operation proactively corrects threshold voltage shifts in erased blocks that would otherwise be caused by the upcoming read disturbance, thereby preventing data errors before they occur.
Solution Approach 2:
The patent implements preliminary anti-action by applying a counteracting read operation with inverted read conditions to compensate for the expected read disturbance. This anti-action counterbalances the harmful effect of the subsequent read operation on erased blocks, maintaining threshold voltage distribution integrity.
2Productivity
If on-chip buffered programming method is used with frequent data input/output commands, then programming speed is improved, but reliability of buffer memory cells decreases due to read disturbances
Solution Approach 1:
The patent applies preliminary action by performing a read disturbance compensation operation on buffer memory cells before transferring data from buffer to main memory. This compensation proactively corrects threshold voltage shifts that would otherwise occur due to frequent read operations on the buffer, maintaining buffer reliability while enabling fast programming.
3Duration of action of stationary object
If threshold voltage distribution shifts or broadens, then memory operation continues, but data storage accuracy deteriorates
Solution Approach 1:
The patent implements feedback by monitoring threshold voltage distribution characteristics and using this information to adjust read operation parameters or apply compensation operations. This feedback mechanism detects shifts or broadening in threshold voltage distribution and corrects them, maintaining data storage accuracy throughout the memory's operational lifetime.
Data Source
AI summary
A method of operating a non-volatile memory device including first buffer memory cells and main memory cells, where the first buffer memory cells store first data, the main memory cells store second data, which is read from the first buffer memory cells, or recovered first data, which is recovered from the second data through a correction process, includes reading data, which is stored in sample buffer memory cells included in the first buffer memory cells, as sample data when an accumulated number of read commands, which are executed on the non-volatile memory device, reaches a reference value. The method includes counting the number of errors included in the sample data based an error correction code, and determining whether the main memory cells store the second data or the recovered first data based on the number of the errors relative to the first threshold value.