SLC Backup Blocks for TLC Memory Error Recovery
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Solution Overview
Problem
In 3D NAND-type flash memory devices, word line shorts can occur during data writing, causing voltage shifts and bit data errors, which necessitate additional data recovery processing, degrading access performance.
Innovation Solution
Configuring additional Single-Level Cell (SLC) memory blocks as backup memory blocks to replace error data in Triple-Level Cell (TLC) memory blocks, thereby avoiding the need for data recovery processing and maintaining access performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If TLC memory blocks are used as data buffer to increase storage capacity, then storage efficiency is improved, but word line short occurs causing data errors and performance degradation
Solution Approach 1:
The patent applies preliminary action by proactively creating SLC backup memory blocks before TLC data buffer blocks are fully utilized. The controller monitors the number of data buffer blocks and preemptively generates backup blocks, transferring data before errors can occur. This prevents word line short-induced errors rather than reacting to them after they happen, resolving the contradiction between using TLC for capacity and maintaining data accuracy.
Solution Approach 2:
The patent implements beforehand cushioning by maintaining SLC memory blocks as backup copies of data stored in TLC data buffer blocks. When word line short occurs in TLC blocks, the intact SLC backup blocks provide a cushion against data loss, allowing error-free data to be retrieved without affecting system reliability. This cushioning mechanism enables the system to safely use TLC blocks for capacity while protecting against their inherent error susceptibility.
2Reliability
If SLC backup memory blocks are configured to prevent data errors, then data reliability is improved, but memory device complexity increases
Solution Approach 1:
The patent applies self-service by implementing automatic monitoring and management of the relationship between TLC data buffer blocks and SLC backup blocks. The controller automatically tracks the number of data buffer blocks, determines when backup blocks are needed, performs data transfer operations, and manages block allocation without external intervention. This automation reduces the operational complexity of maintaining the dual-block system while ensuring data reliability.
Solution Approach 2:
The patent uses parameter changes by dynamically adjusting the number of SLC backup blocks based on the current number of TLC data buffer blocks. The system monitors the data buffer block count and adjusts backup block allocation accordingly, changing operational parameters to maintain optimal reliability without permanently increasing device complexity. This dynamic adjustment allows the system to scale backup resources with actual needs.
3Measurement precision
If data is continuously monitored for errors, then data accuracy is improved, but access performance degrades due to recovery processing
Solution Approach 1:
The patent applies preliminary action by pre-transferring data to SLC backup blocks before TLC blocks become full or errors occur. Rather than continuously monitoring and reacting to errors, the system proactively maintains backup copies, eliminating the need for error-induced recovery processing. This shifts the timing of data protection actions to before problems occur, maintaining high access performance while ensuring data accuracy.
Solution Approach 2:
The patent implements skipping by bypassing the error detection and recovery processing entirely through preventive backup. Instead of monitoring TLC blocks for errors and then performing recovery operations when errors are detected, the system rushes through the data protection process by pre-establishing SLC backups. This eliminates the time-consuming error recovery path while maintaining detection accuracy through the backup mechanism.
Data Source
AI summary
A data storage device includes a memory device and a memory controller. The memory controller configures a first memory block which is a TLC memory blocks as a data buffer, and accordingly configures a plurality of second memory blocks which are SLC memory blocks. The memory controller uses the first memory block to receive data and accordingly store same data in the second memory blocks as backup data. When an amount of available memory space of the first memory block is smaller than or equal to a predetermined amount, the memory controller determines whether any error has occurred in the data stored in the first memory block. When there is any error occurred in the data stored in the first memory block, the memory controller configures a third memory block and move the backup data stored in the second memory block to the third memory block.