Non-volatile Memory Programming Method Reducing Coupling Effect
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Solution Overview
Problem
Conventional non-volatile memory systems face challenges in accurately programming data due to a coupling effect between memory cells, which causes wider variations in threshold voltage, making it difficult to distinguish data and requiring repeated programming with increased threshold voltage, especially when multiple variations overlap.
Innovation Solution
A programming method that involves storing multi-page program data and incrementally increasing the threshold voltage in each program operation, with verification steps to ensure correct programming, allowing the system to reach a desired threshold voltage in a predetermined number of operations, thereby reducing the coupling effect and maintaining a satisfactory window margin between threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional programming method is used, then programming speed is maintained, but coupling effect causes wider threshold voltage variation making data distinction difficult
Solution Approach 1:
The programming process is divided into multiple sequential programming passes, where each pass programs a subset of pages with a specific threshold voltage range. This segmentation allows the system to maintain precise threshold voltage control while reducing the coupling effect by processing pages in staged groups rather than all at once.
Solution Approach 2:
The method performs preliminary programming of certain pages before others, using verification results to determine the optimal programming sequence. By preliminarily programming pages that are less susceptible to coupling effects first, the system establishes a stable baseline that reduces overall threshold voltage variation.
2Measurement precision
If threshold voltage is increased to overcome coupling effect, then data distinction improves, but multiple variations overlap making accurate programming difficult
Solution Approach 1:
The system dynamically adjusts programming parameters including threshold voltage levels, programming pulse characteristics, and verification voltage thresholds based on real-time verification results. This allows the system to maintain clear data distinction while preventing overlap of threshold voltage variations through adaptive parameter optimization.
Solution Approach 2:
The method implements a feedback loop where verification results from each programming operation inform subsequent programming decisions. The system uses verification data to adjust threshold voltage levels and programming parameters, ensuring that multiple threshold voltage variations do not overlap and that programming accuracy is maintained.
3Reliability
If repeated programming is performed to overcome coupling effect, then data reliability improves, but programming time increases significantly
Solution Approach 1:
The system performs preliminary programming of pages that are less susceptible to coupling effects before programming pages that are more susceptible. This preliminary action reduces the need for repeated programming cycles, thereby improving data reliability while minimizing additional programming time.
Solution Approach 2:
By segmenting the programming process into multiple passes with verification between passes, the system identifies and corrects programming errors early. This approach improves data reliability by ensuring each page is correctly programmed before moving to the next, while reducing total programming time by avoiding redundant re-programming of entire pages.
Data Source
AI summary
A programming method for a non-volatile memory system includes storing multi-page program data and buffering the multi-page program data from a page buffer to a memory block and programming the multi-page program data through a predetermined number of program operations. The programming the multi-page program data includes programming memory cells of the memory block using a first threshold voltage lower than a desired threshold voltage based on the multi-page program data sequentially buffered by the page buffer in units of pages and programming the memory cells using the desired threshold voltage by increasing a threshold voltage of the memory cells by a predetermined level at each successive program operation.