NAND Flash Scan Optimization via Multi-Spec Refresh Thresholds
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Solution Overview
Problem
Traditional scans for NAND flash memory devices do not adequately cover multiple reliability margin loss conditions, particularly in terms of data retention and cross-temperature specifications, leading to potential data corruption and performance degradation due to excessive refresh or lack of refresh in high cross-temperature conditions.
Innovation Solution
Implementing a scan optimization method that logs and evaluates parameters such as power-on time, number of scans, and temperature deltas to trigger refreshes based on predefined threshold conditions, ensuring balanced reliability and performance by identifying and addressing specific reliability issues in NAND memory blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional scans are used for NAND flash memory devices, then the scan process is simple, but data reliability is insufficient due to inadequate coverage of multiple reliability margin loss conditions
Solution Approach 1:
The patent segments the reliability specification into multiple independent conditions (data retention specification, cross temperature delta specification, number of program erase cycles specification, number of read cycles specification). Each condition is evaluated separately through logging and threshold comparison, allowing comprehensive reliability assessment without requiring a completely complex scan process.
Solution Approach 2:
The patent performs preliminary actions by logging specification information (power-on time, number of scans, temperature deltas, program erase cycles, read cycles) before the actual scan operation. This preliminary data collection and threshold evaluation enables the system to determine whether a refresh is needed before executing the scan, improving data reliability while maintaining efficient scan processes.
2Reliability
If refresh operations are performed frequently to improve data reliability, then data integrity is enhanced, but system performance deteriorates due to excessive refresh operations
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors and logs specification information (power-on time, number of scans, temperature deltas, program erase cycles, read cycles) and compares these values against predefined thresholds. This feedback loop enables intelligent decision-making about when refresh operations are actually needed, ensuring data integrity while avoiding unnecessary refresh operations that would degrade system performance.
Solution Approach 2:
The patent changes the approach from fixed periodic refresh to dynamic refresh based on multiple parameters including power-on time, number of scans, temperature deltas, program erase cycles, and read cycles. By evaluating these parameters against thresholds, the system optimizes refresh operations to maintain data integrity while minimizing performance impact.
3Productivity
If refresh operations are avoided to maintain system performance, then productivity is improved, but data reliability deteriorates due to potential data corruption in high cross-temperature conditions
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors and logs specification information (power-on time, number of scans, temperature deltas, program erase cycles, read cycles) and compares these values against predefined thresholds. This feedback loop enables intelligent decision-making about when refresh operations are actually needed, ensuring data reliability while avoiding unnecessary refresh operations that would degrade system performance.
Solution Approach 2:
The patent enables the memory system to self-monitor and self-manage its own reliability conditions by logging specification information and automatically determining when refresh operations are needed based on threshold evaluations. This self-service approach ensures data reliability without requiring external intervention or overly conservative refresh strategies that would impact performance.
4Measurement precision
If multiple reliability specifications are monitored to improve data reliability, then measurement precision is enhanced, but device complexity increases due to additional logging and evaluation requirements
Solution Approach 1:
The patent segments the reliability specification into multiple independent conditions (data retention specification, cross temperature delta specification, number of program erase cycles specification, number of read cycles specification). Each condition is evaluated separately through logging and threshold comparison, allowing comprehensive reliability assessment without requiring a completely complex scan process.
Solution Approach 2:
The patent creates a universal logging and evaluation framework that handles multiple different reliability specifications (power-on time, number of scans, temperature deltas, program erase cycles, read cycles) through a unified approach. This multi-functional system can assess various reliability conditions using the same basic mechanism of logging values and comparing against thresholds, reducing overall complexity despite monitoring multiple parameters.
Data Source
AI summary
A variety of applications can include systems and/or methods of optimizing results from scanning a memory device, where the memory device has stacked multiple reliability specifications. Information about a block of multiple blocks of a memory device can be logged, where the information is associated with a combination of reliability specifications. A refresh of the block can be triggered based on exceeding a threshold condition for the combination of reliability specifications.