Non-volatile Memory Cell Short Prevention via Erase Detection
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Solution Overview
Problem
Non-volatile memory systems face data loss due to word line to memory hole shorts, which are difficult to predict and prevent, leading to unreliable data storage.
Innovation Solution
An erase process is performed to detect slow-to-erase memory cells, and those predicted to have future word line to memory hole shorts are prevented from programming to avoid data loss, using techniques such as increasing threshold voltages of select gates or dummy memory cells to inhibit programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are programmed to increase storage capacity, then data storage capability is improved, but data loss due to word line to memory hole shorts occurs
Solution Approach 1:
The patent performs an erase operation on memory cells before programming to detect those that will develop word line to memory hole shorts. By identifying and flagging problematic memory cells in advance through the erase operation, the system prevents data loss by avoiding programming of cells that would otherwise fail, thus maintaining data storage reliability while preserving overall storage capacity.
2Productivity
If all memory cells are used for programming, then storage efficiency is improved, but data loss from undetected shorts increases
Solution Approach 1:
The patent extracts or identifies memory cells that are prone to developing word line to memory hole shorts by performing erase operations and detecting slow-to-erase cells. These problematic cells are separated from the usable memory pool and flagged to prevent programming. This extraction process removes the source of potential data loss while maintaining high storage efficiency by preserving all functional memory cells.
3Reliability
If erase process is performed on all memory cells, then future shorts are detected, but processing time increases
Solution Approach 1:
The patent leverages the mandatory erase operation that is already required before programming in the memory system's normal operation. By detecting slow-to-erase cells during this existing erase process, the system achieves defect detection without requiring additional dedicated detection operations. This self-service approach utilizes the necessary erase step to simultaneously identify problematic cells, thereby maintaining high defect detection accuracy without adding extra processing time.
Data Source
AI summary
To prevent loss of data due to a word line to memory hole short (or another defect), it is proposed to perform an erase process for a plurality of memory cells, detect that a subset of the plurality of memory cells are slow to erase, and prevent successfully programming for at least some of the memory cells that are slow to erase. This technique uses the erase process to predict future word line to memory hole shorts and prevent programming of memory cells predicted to have a future word line to memory hole short so no data will be lost when the short manifests.