Memory Controller Page Writing to Limit NAND Read Disturb
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-volatile NAND flash memory experiences reduced usable space due to dummy data programming in unprogrammed memory cell pages, leading to inefficient storage utilization and compromised data retention from read disturbances.
Innovation Solution
A memory controller method that determines the number of reads of memory cell pages to identify conditions for writing data into adjacent or non-adjacent memory cell pages, and optionally writes dummy data to optimize storage space utilization and reduce read disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is written into unprogrammed memory cell pages to improve storage space utilization, then storage efficiency improves, but read disturbances increase causing data retention degradation
Solution Approach 1:
The patent applies preliminary action by proactively identifying memory cell pages that are susceptible to read disturbances before actual data writing occurs. The controller pre-determines safe writing locations by analyzing read frequency patterns, ensuring that future write operations will not cause data retention issues. This preventive approach allows the system to maximize storage utilization while maintaining data reliability.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring read frequencies of memory cell pages and using this information to dynamically adjust write operations. The controller collects feedback on which pages are frequently read and uses this data to make intelligent decisions about where to write new data, avoiding pages that would cause read disturbances. This closed-loop approach resolves the contradiction between storage efficiency and data retention.
2Reliability
If dummy data is programmed into unprogrammed memory cell pages to maintain data retention, then data reliability improves, but usable storage space decreases
Solution Approach 1:
The patent applies local quality by treating different memory cell pages differently based on their individual read frequency characteristics. Instead of uniformly programming dummy data across all unprogrammed pages or leaving all pages unwritten, the controller selectively determines which specific pages are safe for data writing based on local read patterns. This localized approach allows dummy data to be programmed only where necessary for data retention, maximizing usable storage space while maintaining reliability.
Solution Approach 2:
The patent changes the parameter of page selection criteria from static to dynamic by using read frequency as a variable. The controller adjusts which pages receive dummy data versus which pages are available for actual data writing based on changing read patterns. This parameter-based approach allows the system to optimize the balance between data retention and storage capacity utilization adaptively.
3Productivity
If read frequency monitoring is implemented to identify safe write locations, then storage efficiency improves, but controller complexity increases
Solution Approach 1:
The patent applies self-service by enabling the memory controller to automatically monitor its own read operations and use this self-collected information to optimize write operations. The controller serves itself by generating the read frequency data through normal operation and then using this data to make autonomous decisions about data placement. This self-service approach improves storage efficiency without requiring external monitoring systems or complex external control mechanisms.
Solution Approach 2:
The patent replaces complex mechanical or hardware-based solutions with software-based logic for determining safe write locations. Instead of using complex physical mechanisms to prevent read disturbances, the controller uses logical analysis of read frequency patterns to identify safe pages. This substitution of mechanical complexity with software intelligence achieves storage efficiency improvement while keeping the overall system complexity manageable.
Data Source
AI summary
The present disclosure provides a method operating a memory controller. In response to a data write instruction, the method may include determining a first memory cell block into which data is to be written, the first memory cell block including a first memory cell page programmed and a second memory cell page unprogrammed. In response to the first memory cell block meeting the first condition related to a number of reads of the first memory cell page, the method may include determining that a number of first word lines coupled to the first memory cell page is greater than a first threshold. In response to the number of the first word lines not being greater than the first threshold, the method may include writing data into the second memory cell page coupled to a second word line in the first memory cell block.