Memory Controller Suspend-Resume Verification Restoration
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Solution Overview
Problem
When a program operation is suspended in a memory system, the verification result may be affected, leading to abnormal execution due to changes in threshold voltage distribution, causing issues in resuming the operation and maintaining data integrity.
Innovation Solution
The memory system performs first and second verification operations using different verification voltages, stores temporary values, and upon resumption, executes a third verification operation to restore the original verification results, ensuring consistency and preventing abnormal execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a program operation is suspended and resumed in a memory system, then the quality of service (QoS) for the host is improved, but the verification result may become inaccurate due to changes in threshold voltage distribution
Solution Approach 1:
The patent stores the verification result before suspension in a temporary storage element (first data latch) as a preliminary action. This allows the original verification result to be preserved and restored after resumption, preventing accuracy loss due to threshold voltage changes during the suspend-resume cycle.
Solution Approach 2:
The patent creates a copy of the verification result by storing it in a temporary storage element (first data latch) before suspension. This copy can be restored after resumption to replace the potentially inaccurate new verification result, thereby maintaining verification accuracy despite threshold voltage distribution changes.
2Measurement precision
If multiple verification operations are performed with different verification voltages, then the accuracy of determining memory cell state is improved, but the complexity of the operation increases
Solution Approach 1:
The patent segments the verification process into multiple discrete verification operations (first verification operation with first verification voltage, second verification operation with second verification voltage). Each operation uses a different verification voltage to determine the memory cell state from different thresholds, improving accuracy while maintaining clear operational boundaries.
Solution Approach 2:
The patent dynamically adjusts the verification voltage based on the verification stage. The first verification operation uses a first verification voltage, while the second verification operation uses a second verification voltage that is lower than the first. This dynamic voltage adjustment enables accurate determination of memory cell states at different program levels.
3Productivity
If the verification result is restored after resumption using only the new verification result, then the operation simplicity is maintained, but the data integrity may be compromised due to threshold voltage distribution changes
Solution Approach 1:
The patent implements a feedback mechanism where the restored verification result (from the temporary storage element) is combined with the new verification result after resumption. The control logic uses feedback from both results to determine the final memory cell state, ensuring data integrity while maintaining operational efficiency.
Solution Approach 2:
The patent introduces a temporary storage element (first data latch) as an intermediary that holds the original verification result. This intermediary allows the system to compare and combine the original verification result with the new verification result after resumption, ensuring data integrity without compromising operational efficiency.
Data Source
AI summary
A memory system is provided to include a memory device and a memory controller configured to control the memory device. The memory device includes a first data latch storing information about a state of the memory cell and is configured to: execute a first verification operation and a second verification operation on the memory cell in response to receiving, from the memory controller, a suspend command to suspend a program operation being performed on the memory cell; store, in the first data latch, a temporary value obtained based on a result value of the first verification operation and a result value of the second verification operation; and execute, a resumption command to resume the program operation, a third verification operation, and restore the result value of the first verification operation and the result value of the second verification operation.