Flash Memory Voltage Adjustment for Read-Disturb Mitigation
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Solution Overview
Problem
Rewritable non-volatile memory modules, such as flash memory, experience data loss and reduced lifespan due to the read-disturb phenomenon, where frequent reading operations lead to error bits and incorrect data storage, especially in systems like SSDs that store system data frequently.
Innovation Solution
A data storing method that adjusts the reading voltage for flash memory cells based on a predetermined threshold, using an error checking and correcting circuit to correct page data and program it into alternative memory cells when a significant difference in reading voltage is detected, thereby reducing the frequency of read protection operations and extending the memory module's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frequent reading operations are performed on flash memory, then data accessibility is improved, but read-disturb phenomenon causes data loss and reduces memory lifespan
Solution Approach 1:
The patent applies preliminary action by proactively detecting read-disturb conditions through voltage threshold monitoring before actual data loss occurs. The system continuously monitors the reading voltage threshold of memory cells and predicts potential read-disturb issues, allowing preventive relocation of data before errors manifest, thus maintaining both data accessibility and integrity.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring reading voltage thresholds and using this information to dynamically adjust reading voltages or relocate data. The error checking and correcting circuit provides feedback about data integrity status, which triggers automatic protective actions, creating a closed-loop system that maintains reliability while allowing frequent reads.
2Reliability
If reading voltage threshold is adjusted to prevent read-disturb, then data reliability is improved, but additional voltage adjustment operations increase system complexity
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the reading voltage threshold based on detected conditions. When read-disturb is detected or predicted, the system modifies the reading voltage parameter to a safer level, or relocates data to different memory cells with different voltage characteristics. This dynamic parameter adjustment prevents data loss while using existing hardware capabilities.
Solution Approach 2:
The patent introduces an intermediary error checking and correcting circuit that mediates between the memory cells and the control system. This intermediary monitors voltage thresholds, detects read-disturb conditions, and coordinates protective actions, simplifying the overall control logic while maintaining high reliability through specialized intermediate hardware.
3Measurement precision
If error bit threshold is used to trigger data rewriting, then data accuracy is maintained, but excessive rewriting operations reduce memory lifespan
Solution Approach 1:
The patent applies preliminary action by relocating data based on predictive voltage threshold monitoring rather than waiting for actual error bits to accumulate. By detecting read-disturb conditions through voltage drift before they cause measurable errors, the system proactively relocates data, maintaining accuracy while avoiding the wear caused by reactive rewriting operations triggered by error thresholds.
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
This method effectively prevents data loss from read-disturb and prolongs the lifespan of the memory storage apparatus by minimizing the number of read protection operations, ensuring accurate data storage and reducing wear on the memory cells.
Implementation Method 1
the process of injecting the electrons to the charge-trapping layer 2 is referred to as a programming process
Implementation Method 2
the electric field for crossing the tunnel oxide is raised with the microminiaturization of the process of the flash memory
Data Source
AI summary
A data writing method, and a memory control circuit unit and a memory storage apparatus using the method are provided. The method including: programming data to several memory cells on a first word line of the rewritable non-volatile memory module of the memory storage apparatus, and a first predetermined reading voltage is initially configured for the first word line. The data storing method further includes: adjusting the first predetermined reading voltage to obtain a first available reading voltage for the first word line, and applying the first available reading voltage to the first word line to read first page data. The storing method further includes: if the difference value between the first available reading voltage and the first predetermined reading voltage is larger than a predetermined threshold value, performing a protection operation for the first page data.