Memory Page Backup for Read Disturb Mitigation
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Solution Overview
Problem
Memory systems face challenges in extending the lifespan due to read disturb issues, where frequent read operations can lead to data degradation, especially in memory devices lacking mechanical components like USB drives and SSDs, which rely on electrical methods for data retrieval.
Innovation Solution
A memory device and system that includes a control circuit to manage page backup operations by transferring data from vulnerable pages to a backup block when a predetermined read count is reached, utilizing Error Correction Code operations and ECC circuits to ensure data integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frequent read operations are performed on memory pages, then data access speed is improved, but read disturb causes data degradation and reduces memory lifespan
Solution Approach 1:
The system performs preliminary backup of data from vulnerable pages to safe pages before read disturb occurs. The control circuit monitors read counts and proactively migrates data when threshold is reached, preventing degradation rather than reacting after failure occurs.
Solution Approach 2:
The patent implements copying data from vulnerable pages to backup pages within the memory device. The peripheral circuit reads data from selected pages and writes it to backup pages, creating copies that preserve data integrity while allowing continued read operations on original pages.
2Reliability
If backup operations are performed frequently to prevent read disturb, then data reliability is improved, but additional write operations increase device complexity and wear
Solution Approach 1:
The system applies different protection strategies to different pages based on their vulnerability. The control circuit identifies vulnerable pages with high read counts and applies backup only to those specific pages, rather than uniformly protecting all pages, thereby reducing overall operation complexity.
Solution Approach 2:
The control circuit continuously monitors read counts of pages and uses this feedback to dynamically determine which pages need backup. When a page's read count exceeds the threshold, the system activates backup for that specific page, creating a feedback-driven adaptive protection mechanism.
3Reliability
If all pages are backed up uniformly, then data integrity is maximized, but memory capacity is reduced and write operations increase
Solution Approach 1:
Instead of uniform backup of all pages, the system applies selective backup only to vulnerable pages identified through read count monitoring. This localized approach preserves data integrity where needed while maintaining full capacity for non-vulnerable pages.
Solution Approach 2:
The system performs partial backup action by backing up only the subset of pages that exceed the read count threshold, rather than backing up all pages. This partial action is sufficient to prevent read disturb while avoiding unnecessary write operations and capacity consumption.
Data Source
AI summary
A memory system includes: a memory cell array including a plurality of memory blocks; a peripheral circuit configured to perform a read operation on a selected memory block among the plurality of memory blocks and a backup program operation on a backup block among the plurality of memory blocks; and a control circuit configured to control the peripheral circuit to backup data of logical pages included in the selected memory block in the backup block, when a read count of a selected physical page of the selected memory block is equal to or larger than a set value in the read operation on the selected memory block.