Non-volatile Memory Read Reclaim Determination
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Solution Overview
Problem
Non-volatile memory devices face reliability issues due to changes in threshold voltage distributions caused by factors like retention, read disturb, and hot-carrier injection, which can lead to reduced performance and data integrity.
Innovation Solution
A method and system for determining whether a read reclaim is required in a non-volatile memory device, involving an on-chip read operation to generate distribution information, and using this information along with environment data to decide on the need for a read reclaim operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage controller determines read reclaim needs by performing on-chip read operations, then the determination accuracy and reliability are improved, but the device complexity and processing time increase
Solution Approach 1:
The read reclaim determination process is segmented into multiple stages: first performing a lightweight on-chip read operation to obtain distribution information, then using this information to determine whether a full read reclaim is necessary. This segmentation allows the system to achieve reliable determination while reducing overall complexity by not always performing the most complex operation.
Solution Approach 2:
The patent performs a preliminary on-chip read operation to gather distribution information before making the final read reclaim determination. This preliminary action provides the necessary data for accurate decision-making while keeping the initial processing lightweight, thus improving reliability without immediately incurring the full complexity cost.
2Reliability
If the storage controller performs frequent read operations to monitor threshold voltage distribution, then the reliability monitoring is improved, but the input/output load and latency increase
Solution Approach 1:
The patent performs partial read operations (on-chip read) instead of full read operations every time. This partial action is sufficient to obtain the necessary distribution information for determination while significantly reducing the time and I/O load compared to full read operations, thus resolving the contradiction between monitoring accuracy and latency.
Solution Approach 2:
The non-volatile memory device performs self-monitoring of its own threshold voltage distribution through on-chip read operations. This self-service capability allows the device to determine its own read reclaim needs without requiring continuous external controller intervention, reducing latency and I/O load while maintaining reliable monitoring.
3Speed
If the storage controller uses on-chip read operations to generate distribution information, then the processing speed is improved, but the energy consumption increases
Solution Approach 1:
The patent employs partial read operations that read only the necessary distribution information from the memory cells rather than performing full read operations. This partial action achieves the required processing speed for timely determination while consuming significantly less energy than complete read operations would require.
Data Source
AI summary
A method of operating a non-volatile memory device, which is configured to communicate with a storage controller includes: receiving a first request indicating a read reclaim determination and including environment information from the storage controller, performing a first on-chip read operation for generating first distribution information based on the first request, determining whether a read reclaim is required based on the first distribution information, and providing the storage controller with a determination result having a first bit value in response to determining that the read reclaim is required.