Memory Page Reprogram Control for Read Failure Bit Recovery
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Solution Overview
Problem
Non-volatile memory devices experience increased wear and reduced reliability due to frequent data refresh operations caused by charge loss, leading to inaccurate data reading and shortened service life.
Innovation Solution
A memory system that performs a reprogram operation on memory cell pages with a threshold voltage offset by using a memory controller to detect read failure bits and execute error correction, followed by a reprogram operation to correct data and adjust threshold voltages, thereby reducing the need for data refresh and extending the device's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data refresh operations are performed frequently to correct charge loss, then data accuracy is improved, but memory device wear increases and service life decreases
Solution Approach 1:
The patent performs preliminary detection of threshold voltage offsets and identifies memory cell pages requiring reprogram operations before data accuracy degrades significantly. By proactively reprogramming pages with threshold voltage offsets adjacent to unprogrammed pages, the system prevents charge loss-induced errors without requiring frequent comprehensive data refresh operations, thus extending memory device service life while maintaining data accuracy.
2Reliability
If reprogram operations are performed on memory cell pages with threshold voltage offset, then data accuracy and reliability are improved, but the number of erase cycles increases
Solution Approach 1:
The patent applies local quality by selectively reprogramming only specific memory cell pages that have threshold voltage offsets adjacent to unprogrammed pages, rather than performing blanket reprogram operations on entire memory blocks. This targeted approach addresses reliability issues locally where they occur, minimizing the total number of erase cycles while maintaining data accuracy in critical areas.
Solution Approach 2:
The patent changes the parameter selection criterion for reprogram operations from comprehensive block-level operations to selective page-level operations based on threshold voltage offset detection. By changing the granularity and selection criteria, the system achieves the same reliability improvement with fewer total erase cycles, as it only reprograms pages that actually require correction.
3Measurement precision
If comprehensive data refresh is performed on all memory pages, then data accuracy is maintained, but operation complexity and time consumption increase
Solution Approach 1:
The patent segments the memory device into individual memory cell pages and evaluates each page's need for reprogram operations based on its specific characteristics (threshold voltage offset adjacent to unprogrammed pages). This segmentation allows the system to apply complexity only where necessary, rather than uniformly across the entire memory device, reducing overall operation complexity while maintaining data accuracy.
Solution Approach 2:
The patent implements a self-service mechanism where the memory controller autonomously detects threshold voltage offsets, identifies pages requiring reprogram operations, and executes corrective actions without external intervention. This self-service approach simplifies the overall system operation by automating the complexity of selective data refresh, reducing the need for complex external control while maintaining data accuracy.
Data Source
AI summary
A memory system comprises: a memory device including a first word line; and a memory controller coupled to the memory device and configured to: acquire the number of read failure bits of a memory cell page coupled to the first word line; determine whether the number of read failure bits of the memory cell page is greater than a preset threshold; and control the memory device to perform a reprogram operation on the memory cell page in response to the number of read failure bits of the memory cell page being greater than the preset threshold.