Memory Programming Control for Elapsed-Time Reliability
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Solution Overview
Problem
As the number of bits of data stored in memory cells increases, the interval between threshold voltages narrows, leading to reduced reliability in memory devices.
Innovation Solution
A memory device and method that includes a control circuit to check the elapsed time between program operations and switch between normal and dummy program operations based on elapsed time intervals, ensuring reliable data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of bits of data stored in memory cells increases, then storage capacity is improved, but the interval between threshold voltages becomes narrow and reliability is reduced
Solution Approach 1:
The patent applies dynamics by making the program operation type variable rather than fixed. The control circuit dynamically switches between normal program operations and dummy program operations based on the elapsed time since the previous program operation. This dynamic adjustment allows the system to adapt to different time intervals, thereby maintaining reliable threshold voltage intervals even when storing multiple bits per cell
Solution Approach 2:
The patent changes the parameter of program operation type (normal vs. dummy) based on the elapsed time parameter. When the elapsed time exceeds a reference threshold, the system transitions from normal program operations to dummy program operations. This parameter change mechanism compensates for the narrowed threshold voltage intervals caused by multi-bit storage, thereby maintaining reliability while achieving high storage capacity
2Productivity
If normal program operations are performed continuously without considering elapsed time, then productivity is improved, but reliability deteriorates when elapsed time is long
Solution Approach 1:
The patent implements feedback by having the control circuit monitor the elapsed time between program operations and use this information to determine the next program operation type. This feedback loop ensures that when sufficient time has passed since the previous operation, the system switches to dummy program operations to maintain reliability, while allowing continuous normal operations when time intervals are appropriate
Solution Approach 2:
The system dynamically adjusts the program operation schedule based on real-time elapsed time measurements. Rather than following a fixed program sequence, the system adapts its operation type (normal or dummy) based on the actual time elapsed since the previous program operation, thereby balancing productivity and reliability
Data Source
AI summary
A memory device, and a method of operating the same, includes checking a first elapsed time between an end time of a program operation performed on a first page and a selection time when a second page is selected after the end time, comparing the first elapsed time with a reference time interval, and performing a dummy program operation on the second page when the first elapsed time is equal to or longer than the reference time interval.