Bipolar Read Retry for Non-Volatile Memory Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Memory cells in non-volatile memory systems experience read disturb issues due to threshold voltage drift over time, leading to errors in data retrieval, especially as the cells age, which existing technologies struggle to mitigate effectively.
Innovation Solution
The implementation of bipolar read retry, where read voltage pulses are applied in both polarities to ensure uniform conductivity of memory cells, reducing read disturb and maintaining data readability by minimizing voltage stress across memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If read voltage pulses are applied to memory cells during read operations, then data can be retrieved from the memory cells, but threshold voltage drift occurs leading to read disturb errors
Solution Approach 1:
The patent applies preliminary anti-action by implementing bipolar read retry operations that proactively counteract threshold voltage drift before it causes read errors. The system performs read operations with both positive and negative voltage polarities, and when errors are detected, it retries with opposite polarity to compensate for the drift that occurred during the first read attempt.
Solution Approach 2:
The patent implements periodic action through retry mechanisms that are triggered periodically when read errors are detected. The system performs initial read operations, monitors for errors, and selectively retries failed reads with opposite polarity, creating a periodic correction cycle that maintains data integrity over time.
2Measurement precision
If higher read voltage magnitude is used to improve signal detection, then reading accuracy improves, but voltage stress on memory cells increases accelerating degradation
Solution Approach 1:
The patent applies inversion by using opposite voltage polarities for retry read operations. When the first read with a certain polarity fails, the system retries with the opposite polarity, effectively inverting the voltage stress direction to compensate for drift and reduce cumulative damage from repeated high-stress reads in the same direction.
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
Bipolar read retry effectively reduces the impact of read disturb on memory cells, ensuring accurate data retrieval by maintaining well-separated voltage regions and minimizing errors, thus enhancing the reliability of data storage and retrieval processes.
Implementation Method 1
The read operation determines the state of the memory cell by applying a voltage and determining whether the memory cell becomes conductive at a voltage corresponding to a pre-defined state
Data Source
AI summary
Systems, methods and apparatus to implement bipolar read retry. In response to a determination that a first result of reading a set of memory cells using a first magnitude of read voltage is erroneous, a second magnitude of read voltage, greater than the first magnitude, is identified for the bipolar read retry. In the retry, a controller uses voltage drivers to apply, to the set of memory cells, first voltages of the second magnitude in a first polarity to obtain a second result of reading the set of memory cells and, after the second result is generated and in parallel with decoding the second result, apply second voltages of the second magnitude in a second polarity, opposite to the first polarity.