Nonvolatile Memory Sub-Block Erasure and Data Backup
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Solution Overview
Problem
Conventional nonvolatile memory devices can only erase a block unit, leading to inefficiencies when dealing with sub-blocks, as adjacent sub-blocks can be inadvertently erased due to coupling phenomena, affecting data integrity and storage speed.
Innovation Solution
A method and device for a nonvolatile memory with a three-dimensional array structure that allows for sub-block erasure and reprogramming, involving backup and restoration of data from adjacent sub-blocks to prevent unwanted erasure and improve storage speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block unit erasure is performed in conventional nonvolatile memory devices, then erasure operation can be completed, but adjacent sub-blocks are inadvertently erased due to coupling phenomena, affecting data integrity
Solution Approach 1:
The memory block is divided into multiple sub-blocks, allowing selective erasure of only the requested sub-block while protecting adjacent sub-blocks from inadvertent erasure due to coupling phenomena. This segmentation enables precise control over erasure operations.
Solution Approach 2:
Data from adjacent sub-blocks is backed up to a buffer circuit before the erasure operation begins. This preliminary backup action ensures that even if coupling effects cause unintended erasure, the original data can be restored afterward.
2Productivity
If sub-block erasure is enabled to improve storage speed, then erasure efficiency is enhanced, but data integrity may be compromised due to coupling phenomena
Solution Approach 1:
Dividing the block into sub-blocks enables faster selective erasure operations while maintaining data protection through the backup mechanism for adjacent sub-blocks.
Solution Approach 2:
A buffer circuit is introduced as an intermediary to temporarily store backup data from adjacent sub-blocks during erasure operations, protecting the original data from loss due to coupling effects.
3Reliability
If backup and reprogramming operations are performed on adjacent sub-blocks, then data integrity is maintained, but additional operations increase processing time
Solution Approach 1:
The backup of adjacent sub-block data is performed as a preliminary step before the requested sub-block erasure, allowing rapid restoration without extending the critical erasure path.
Solution Approach 2:
The backup operation is integrated into the erasure workflow as a continuous process, utilizing the same operational infrastructure and minimizing idle time between backup and restore operations.
Data Source
AI summary
A method of operating a storage device having a nonvolatile memory including at least one memory block having a plurality of sub-blocks includes reading backup data of backup memory cells having a highest program state among a plurality of memory cells connected to at least one word line of a sub-block which is not erase-requested adjacent to an erase-requested sub-block among the sub-blocks. The method includes storing the backup data, erasing the erase-requested sub-block, and reprogramming the backup memory cells having the highest program state on the basis of the backup data.