Memory Die Integrity Scanning Based on Read Margin Degradation
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Solution Overview
Problem
Conventional memory sub-systems perform data integrity checks at a fixed frequency, which can lead to overscanning, increased power consumption, and reduced system performance due to die-to-die variations and read disturb issues, without adequately accounting for the varying reliability of memory devices.
Innovation Solution
Adaptive integrity scanning is implemented using lower page calibration, where the memory sub-system controller adjusts scan frequencies based on read margins of individual memory dies, optimizing the frequency according to their specific degradation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed frequency data integrity checks are performed, then data reliability is maintained, but power consumption increases and system performance decreases due to overscanning
Solution Approach 1:
The patent implements dynamic scan frequency adjustment based on read margin measurements. The controller adapts the integrity scan frequency for each memory die individually, transitioning from a static fixed frequency to a dynamic parameter that responds to actual memory conditions. This resolves the contradiction by performing scans only when necessary based on measured degradation rates.
Solution Approach 2:
The patent changes the scan frequency parameter based on measured read margins and degradation rates. By monitoring lower page calibration data and adjusting the scan interval accordingly, the system optimizes between maintaining data integrity and reducing unnecessary scans that consume power.
2Reliability
If fixed frequency data integrity checks are performed, then data reliability is maintained, but system performance decreases due to unnecessary scans
Solution Approach 1:
The system dynamically adjusts scan frequency based on actual memory die degradation rates measured through lower page calibration. Memory dies with stable read margins experience reduced scan frequencies, freeing up system resources and improving overall performance while maintaining integrity checks where needed.
Solution Approach 2:
The scan frequency parameter is changed based on measured read margin stability. The controller modifies the integrity scan interval for each die according to its specific degradation characteristics, reducing unnecessary scans that degrade system performance while maintaining adequate monitoring where degradation is detected.
3Device complexity
If uniform scan frequency is applied to all memory dies, then implementation simplicity is maintained, but reliability decreases due to die-to-die variations
Solution Approach 1:
The patent applies local quality by treating each memory die individually with its own measured read margin characteristics. Instead of uniform scan frequencies, each die receives a customized scan interval based on its specific degradation rate, improving reliability while the automated measurement process keeps implementation complexity manageable.
Solution Approach 2:
The system performs preliminary lower page calibration measurements to establish baseline read margins before determining scan frequencies. This preliminary action captures die-to-die variations early, enabling reliable differentiated scan scheduling without requiring complex real-time monitoring during normal operation.
4Productivity
If lower page calibration is used for adaptive scanning, then scan optimization is improved, but measurement precision requirements increase
Solution Approach 1:
Lower page calibration is performed as a preliminary measurement step to establish baseline read margins before normal operation. This preliminary action provides the precision measurements needed for adaptive scan frequency determination without requiring continuous high-precision monitoring during normal memory operations.
Solution Approach 2:
The system uses lower page calibration data as a representative sample to infer the degradation characteristics of the entire memory die. By measuring a calibrated subset of memory cells, the system obtains sufficient precision information to determine appropriate scan frequencies for the whole die without requiring exhaustive measurement.
Data Source
AI summary
A processing device in a memory sub-system detects an occurrence of a data integrity check trigger event in the memory sub-system, and in response, identifies a memory die of a plurality of memory dies in the memory sub-system. The processing device further determines a read margin associated with a first distribution of memory cells of the identified memory die, and determines an adaptive scan frequency for the identified memory die based on the read margin associated with the first distribution of memory cells.