Non-volatile Memory Suspend-Resume Voltage Control
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Solution Overview
Problem
Flash memory devices experience deterioration in program threshold voltage distribution due to the time interval between suspend and resume states during program operations, leading to potential read failures and reduced reliability.
Innovation Solution
A non-volatile memory device and programming method that include a control circuit to manage the device's state by terminating the verify operation of a program loop upon receiving a suspend request, allowing for reduced voltage differences between program loops and minimizing threshold voltage distribution deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the verify operation is performed completely before entering suspend state, then the program threshold voltage distribution is maintained, but the programming time increases
Solution Approach 1:
The patent applies preliminary action by performing a preliminary verify operation before entering suspend state to assess the program threshold voltage distribution status. Based on this preliminary verification, the system decides whether to enter suspend state or continue programming, thus maintaining reliability while enabling time savings through early suspend decision-making.
Solution Approach 2:
The patent implements dynamics by making the verify operation depth adjustable and adaptive. The system dynamically determines the verify operation termination point based on program threshold voltage distribution characteristics, allowing flexible balance between verification thoroughness and programming speed, rather than always completing full verify operations.
2Productivity
If the verify operation is terminated early to reduce programming time, then the programming speed increases, but the program threshold voltage distribution deteriorates
Solution Approach 1:
The patent applies feedback by continuously monitoring program threshold voltage distribution characteristics during the verify operation and using this feedback to dynamically adjust the verify operation termination decision. The system feeds back the distribution status to determine whether to continue verification or enter suspend state, ensuring reliability is maintained while enabling early suspend when appropriate.
3Reliability
If the program voltage difference between loops is reduced to prevent threshold voltage deterioration, then the threshold voltage distribution is maintained, but the programming efficiency decreases
Solution Approach 1:
The patent implements dynamics by making the program voltage difference adaptive rather than fixed. The system dynamically adjusts the program voltage difference between loops based on the program threshold voltage distribution characteristics observed during verify operations, allowing larger voltage differences when distribution is good (improving efficiency) and smaller differences when distribution deteriorates (maintaining reliability).
Data Source
AI summary
A non-volatile memory device includes: a memory cell array including a plurality of memory cells connected to a plurality of word lines and a plurality of bit lines, a row decoder configured to selectively control the plurality of word lines, a page buffer including a plurality of latches corresponding to the plurality of bit lines, respectively, and a control circuit configured to control the non-volatile memory device to enter a suspend state after terminating a verify operation of a program loop of a program operation of the plurality of memory cells in response to a suspend request being generated during an execution operation of the program loop.