Non-volatile Memory Progressive Writes Without Erase
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Solution Overview
Problem
The existing non-volatile memory systems require a traditional erase operation to change the threshold voltage of memory cells back to the original erased state, which slows down the programming process and uses extra space, as all valid data in a block must be moved and re-programmed when overwriting data, especially when transitioning from SLC to MLC or vice versa.
Innovation Solution
The proposed solution involves progressive writing of data without performing a traditional erase operation by using shifted threshold voltage distributions, allowing new data to be written on top of old data without reverting memory cells to the initial erased state, thereby enabling quicker programming and reduced memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional erase operation is performed to overwrite data, then data can be rewritten, but programming speed decreases and extra memory space is required
Solution Approach 1:
The patent changes the threshold voltage parameter approach by not returning it to the original erased state after programming. Instead of traditional erase-program cycles, the system performs progressive writes that shift threshold voltage distributions to new states, eliminating the need for full erase operations and enabling faster rewriting.
Solution Approach 2:
The patent applies preliminary actions by pre-positioning threshold voltage distributions in intermediate states that allow subsequent writes to proceed without full erasure. This preliminary positioning of voltage states enables direct overwriting and eliminates the time-consuming traditional erase step.
2Productivity
If traditional erase operation is performed to overwrite data, then data can be rewritten, but memory space efficiency decreases
Solution Approach 1:
The patent utilizes parameter changes in threshold voltage distributions to enable progressive writing. By shifting voltage distributions to new states rather than returning to the original erased state, the system eliminates the need for additional memory space that would otherwise be required for erase operations and data migration.
Solution Approach 2:
The memory system performs self-service by maintaining its own threshold voltage distributions in progressive states without requiring external erase operations or additional memory resources. The system serves itself by enabling direct overwriting through controlled voltage shifts.
3Productivity
If threshold voltage is shifted to new states for progressive writing, then programming speed increases, but detection complexity increases
Solution Approach 1:
The patent implements feedback mechanisms to track and detect the progressive threshold voltage states. By monitoring the shifted distributions and providing feedback on the current state, the system maintains programming speed while enabling accurate detection of the new voltage states through controlled feedback loops.
Data Source
AI summary
A non-volatile storage system includes a control circuit connected to non-volatile memory cells provides for progressive writing of data. That is, existing data is overwritten by new data without performing a traditional erase operation that changes the threshold voltage of the memory cells back to the traditional or original erase state. In one example, new data is written on top of old data using shifted threshold voltage distributions. Some embodiments include writing MLC data over SLC data, using intermediate erase threshold voltage distributions and/or automatically detecting which threshold voltage distributions are currently being used to store data.