Memory Sub-Block Protection Through Word-Line Reliability Checks
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Solution Overview
Problem
Existing non-volatile memory systems face challenges in identifying and addressing reliability issues in word lines, leading to potential uncorrectable errors and reduced operational efficiency.
Innovation Solution
A non-volatile storage apparatus and method that transitions between operating modes to perform a check operation on word lines, dividing blocks into sub-blocks for reliability assessment, and determining if the block can operate in a second mode based on the check results, assigning some word lines as dummy lines to mitigate issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check operation is performed on all word lines before mode transition, then reliability is improved, but operational time is increased
Solution Approach 1:
The patent divides the block into multiple sub-blocks, each with its own set of word lines that can be checked independently. This segmentation allows the check operation to be performed on smaller portions of the memory structure, reducing the total time required while maintaining comprehensive reliability assessment across all word lines.
2Reliability
If word lines are assigned as dummy word lines to mitigate reliability issues, then reliability is improved, but storage capacity is reduced
Solution Approach 1:
The patent applies different operational characteristics to different word lines within the same block. Specifically, certain word lines are designated as dummy word lines with specialized functionality for maintaining reliability, while other word lines remain as data word lines for normal storage operations. This local differentiation allows reliability enhancement without uniformly reducing storage capacity across the entire block.
Data Source
AI summary
Embodiments disclosed herein are directed to an apparatus including a control circuit connected to the word lines and bit lines. The control circuit is configured to: in response to transitioning from a first operating mode to a second operating mode, perform a check operation for identifying reliability issues on a set of word lines of a memory block; and in response to results of the check operation, determine if the block can be operated in the second operating mode. In the first operating mode, the set of the word lines are assigned as data word lines and are eligible to store user data and in the second operating mode, the set of the word lines are assigned as dummy word lines and ineligible to store user data.