Flash Memory Base Data Migration for Reflow Heat Protection
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Solution Overview
Problem
Non-volatile semiconductor memory devices, such as flash memory devices, face data loss during reflow processes due to heat generated, which can also occur during rework, compromising base data integrity.
Innovation Solution
A storage device with a non-volatile memory system featuring first and second memory regions of different reliability levels, controlled by a controller to migrate and restore base data between these regions to protect against heat-induced loss during reflow and rework processes, using management information to manage the operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base data is stored in the first memory region during normal operation, then storage capacity and performance are optimized, but data reliability deteriorates during rework processes due to heat exposure
Solution Approach 1:
The non-volatile memory device is divided into two distinct memory regions: a first memory region for normal base data storage and a second memory region for backup storage. This segmentation allows the system to maintain data in the primary location during normal operation while having a protected backup location available for rework scenarios, thus improving data reliability without requiring complete redundancy of the entire storage system.
Solution Approach 2:
The controller performs preliminary actions by automatically detecting rework conditions (such as temperature changes or host commands) and proactively migrating base data from the first memory region to the second memory region before the rework process begins. This preliminary migration ensures data is protected in advance, preventing data loss during the subsequent heat exposure of the rework process.
2Reliability
If base data is protected against rework processes, then data integrity is maintained, but operational flexibility deteriorates due to limited base data protection operations
Solution Approach 1:
The system implements dynamic base data protection operations where the controller can adaptively choose between different protection strategies based on current operational conditions. The controller monitors various parameters (temperature, host commands, rework detection) and dynamically decides whether to migrate data to the second memory region, maintain data in the first region, or perform other protection actions, thus providing operational flexibility while maintaining data integrity.
Solution Approach 2:
The system changes operational parameters such as memory region allocation, data migration timing, and protection operation modes based on detected conditions. For example, the controller can adjust the threshold for triggering data migration, change the state of memory regions between active and protected modes, and modify the frequency of data verification operations, allowing flexible adaptation to different rework scenarios while maintaining data integrity.
3Reliability
If data is migrated to the second memory region before rework, then data loss is prevented, but processing time increases due to migration and restoration operations
Solution Approach 1:
The controller performs data migration to the second memory region as a preliminary action before the rework process begins, based on early detection of rework conditions such as temperature rise or specific host commands. By completing the migration beforehand, the system prevents data loss during the actual rework while minimizing the impact on operational time, as the migration occurs during the preparation phase rather than during the rework itself.
Solution Approach 2:
The system implements efficient data migration and restoration operations that minimize processing time by optimizing the transfer process. The controller can perform rapid data copying between memory regions using direct memory access techniques, and can selectively migrate only the necessary portions of base data rather than the entire storage capacity, thus reducing the time required for protection operations while maintaining effective data protection.
Data Source
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AI summary
A storage device includes a non-volatile memory device including a first memory region and a second memory region, memory cells of the first memory region being at different levels from memory cells of the second memory region and a controller configured to control a base data protection operation against a rework for a reflow process by including a first operation of migrating base data stored in the first memory region to the second memory region before the rework for a first reflow process and a second operation of restoring the base data from the second memory region to the first memory region after completing the rework for the reflow process. The controller is configured to provide, to a host, management information including at least one of first information on a current state in a base data protection operation against the rework, second information on the first memory region, and third information on the second memory region.