Non-volatile Memory Data Recovery via Reference Current Adjustment
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Solution Overview
Problem
Non-volatile semiconductor memory devices, such as flash memory, suffer from data retention issues due to electron leakage or insertion, leading to data errors over time, especially at higher temperatures, which existing technologies fail to effectively recover.
Innovation Solution
A method and apparatus for recovering data by controlling the reference current in non-volatile semiconductor memory devices, involving a buffer memory to store read data and rewriting it to memory cells, with the reference current being adjusted based on a recovery command signal to correct logic levels, thereby addressing data errors caused by deteriorated retention capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrons are implanted in floating gate using F-N tunneling mechanism to store data, then data storage capability is achieved, but data retention characteristic deteriorates over time due to electron leakage or insertion
Solution Approach 1:
The patent applies preliminary action by performing data recovery operations before data errors become permanent. The system detects deteriorated retention characteristics and proactively recovers data by adjusting reference current and rewriting data to buffer memory, preventing complete data loss from electron leakage or insertion in the floating gate.
Solution Approach 2:
The patent changes the reference current parameter dynamically to compensate for deteriorated data retention. By adjusting the reference current level based on detected retention characteristics, the system maintains accurate data reading capability even when electron leakage or insertion affects the floating gate charge.
2Reliability
If reference current is controlled to recover data, then data recovery capability is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent implements feedback by continuously monitoring data retention characteristics and using this information to adjust reference current control. The system measures retention performance, compares it against thresholds, and automatically modifies reference current levels accordingly, creating a closed-loop control system that improves data recovery without requiring complex external intervention.
Solution Approach 2:
The patent applies self-service by enabling the memory device to automatically detect its own retention characteristic deterioration and perform self-recovery operations. The device monitors its own floating gate electron leakage or insertion and autonomously adjusts reference current and rewrites data to buffer memory without requiring external system intervention.
3Reliability
If data is repeatedly read and rewritten to buffer memory, then data errors are corrected, but operation time increases due to additional write cycles
Solution Approach 1:
The patent applies periodic action by performing data recovery operations at scheduled intervals or when retention characteristics reach predetermined thresholds. Instead of continuous monitoring and recovery, the system periodically assesses retention status and executes recovery only when necessary, reducing unnecessary write cycles while maintaining data integrity.
Solution Approach 2:
The patent changes operational parameters dynamically by adjusting reference current levels based on detected retention characteristics. This allows the system to optimize the balance between reading accuracy and write operation frequency, performing data rewriting only when retention deterioration exceeds acceptable thresholds, thereby minimizing additional operation time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively recovers data by adjusting the reference current to match the cell current, reducing data errors and improving the reliability of non-volatile memory devices even as data retention capabilities decline.
Implementation Method 1
A flash memory device may store data in a first logic level and a second logic level according to whether electrons are implanted in a floating gate using an F-N (Fowler-Nordheim) tunneling mechanism.
Implementation Method 2
Current output from a memory cell selected by the row decoder 17-1 and the column decoder 17-2 and a reference current output from the reference current generation block 11 are compared by the sense amplifier 13 so as to be divided into a first logic level, for example, '0', and a second logic level, for example, '1'.
Data Source
AI summary
A method and device for recovering data in a non-volatile semiconductor memory device that may include controlling a reference current by the non-volatile semiconductor memory device, reading data of at least one memory cell based on the controlled reference current, storing the read data in a buffer memory, and writing the data stored in the buffer memory to the at least one memory cell.