Memory Controller Dancing Bit Detection and Erase
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Solution Overview
Problem
In NAND flash memory systems, data accuracy and reliability are compromised due to differences in write speed between lower and upper physical pages, leading to potential data loss when errors occur during programming.
Innovation Solution
A data storing method and memory controller that manage physical erase units by selecting valid data from one physical erase unit and moving it to another if it contains a 'dancing bit', ensuring accurate data storage by executing an erasing operation on such units to prevent data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored in physical erase units with multiple physical pages, then storage capacity is improved, but data reliability deteriorates due to dancing bits caused by write speed differences between pages
Solution Approach 1:
The patent applies preliminary action by performing an erasing operation on a physical erase unit before storing new data, when dancing bits are detected. This preventive measure eliminates potential data corruption before it occurs, ensuring that new data is written to a clean state without residual charges that could cause reliability issues.
Solution Approach 2:
The patent converts the harmful effect of dancing bits into a benefit by using them as indicators to trigger erasing operations. Instead of allowing dancing bits to cause data corruption, the system detects them and uses their presence as a signal to perform preventive erasing, thereby transforming a reliability threat into a mechanism for ensuring data integrity.
2Reliability
If erasing operation is performed on physical erase units containing dancing bits, then data reliability is improved, but productivity deteriorates due to additional erasing operations
Solution Approach 1:
The patent implements feedback by detecting dancing bits in physical erase units and using this information to control subsequent erasing operations. The system continuously monitors for dancing bits and adjusts its behavior accordingly, performing erasing only when dancing bits are present, thus optimizing the balance between reliability and productivity.
Solution Approach 2:
The patent changes the operational parameter of the physical erase unit by performing an erasing operation that transitions the unit from a charged state to a neutral state. This parameter change eliminates dancing bits and prepares the unit for reliable data storage, directly improving data reliability when dancing bits are detected.
3Manufacturing precision
If valid data is moved between physical erase units, then data integrity is improved, but device complexity increases due to data management operations
Solution Approach 1:
The patent applies taking out by extracting valid data from a physical erase unit that contains dancing bits and moving it to a different physical erase unit. This separation isolates the corrupted data environment from the valid data, ensuring data integrity by preventing corruption while managing the data movement through the controller.
Data Source
AI summary
A data storing method for a rewritable non-volatile memory module and a memory controller and a memory storage device using the same are provided. The data storing method includes moving or writing data into a physical erase unit of the rewritable non-volatile memory module and determining whether the physical erase unit contains a dancing bit. The data storing method further includes when the physical erase unit contains the dancing bit, restoring the rewritable non-volatile memory module to the state before the data is moved or moving the data from the physical erase unit to another physical erase unit. Thereby, the data storing method can effectively ensure the reliability of the data.