Partial Block Erase for Non-Volatile Memory Read Disturbance
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Solution Overview
Problem
Non-volatile memory devices face issues with read disturbances during open block reading, leading to erroneous data due to soft programming of unprogrammed memory cells, which can result in incorrect threshold voltage shifts and data corruption.
Innovation Solution
Implementing a partial block erase with optional limitations on programming in the unprogrammed region of a memory block to mitigate read disturbances, by performing partial block erase verification and adjusting programming voltages to prevent unintended programming of unprogrammed cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read operations are performed on programmed regions of a memory block, then data can be accessed, but read disturbances occur in unprogrammed regions causing soft programming and data corruption
Solution Approach 1:
The patent applies preliminary anti-action by performing a partial block erase operation on unprogrammed regions before they are affected by read disturbances. The controller detects open block reads and proactively erases the unprogrammed regions to prevent soft programming from occurring, thereby maintaining data integrity without waiting for actual corruption to happen.
Solution Approach 2:
The patent implements preliminary action by closing open blocks through erase operations before subsequent programming operations are attempted. The controller tracks read operations and performs preventive erase actions on unprogrammed regions before they can be inadvertently programmed by read disturbances, ensuring reliable data storage.
2Reliability
If partial block erase is performed to mitigate read disturbances, then data integrity is improved, but additional programming operations are required increasing device complexity
Solution Approach 1:
The patent employs feedback mechanisms where the controller continuously monitors the programming state of memory blocks and detects open block conditions. Based on this feedback, the controller dynamically determines when partial block erase operations are needed and manages the erase-program sequence accordingly, automating the complexity management.
Solution Approach 2:
The controller performs self-service by automatically tracking which blocks are open and which regions require erase operations. The system manages its own state without external intervention, automatically initiating partial block erase when needed and coordinating subsequent programming operations, thereby handling the increased complexity internally.
3Reliability
If unprogrammed regions are erased to prevent soft programming, then read disturbances are reduced, but programming time is increased due to additional erase operations
Solution Approach 1:
The patent applies partial action by performing erase operations only on the specific unprogrammed regions that are at risk of read disturbances, rather than erasing entire blocks unnecessarily. This selective partial erase approach minimizes the time penalty while still protecting against soft programming in vulnerable regions.
Solution Approach 2:
The patent segments the memory block into programmed and unprogrammed regions, applying different operations to each segment. The partial block erase is applied only to unprogrammed regions that need protection, while already programmed regions are left intact, thereby reducing the total erase time compared to full block operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces read disturbances and data corruption by ensuring accurate programming and reading states, maintaining data integrity and reliability in non-volatile memory systems.
Implementation Method 1
VPGM is applied to the control gate and the bit line is grounded, causing electrons from the channel of a cell or memory element, e.g., storage element, to be injected into the floating gate
Data Source
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AI summary
A non-volatile memory system mitigates the effects of open block reading by analyzing the un-programmed region of a block before programming to determine a potential for read disturbance. The system may perform partial block erase verification based on a read count value associated with open block reading of the memory block. To mitigate the effects of open block read disturbance, the system performs partial block erase for the un-programmed region of the memory block, and may limit programming in the un-programmed region.