Wordline-Aware Data Migration in XLC Memory for Data Retention
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Solution Overview
Problem
Memory devices face challenges in maintaining data retention and longevity due to charge leakage exacerbated by high temperatures and increasing lateral charge migration, particularly in high-density multi-level cell memories, leading to reduced reliability and increased error rates.
Innovation Solution
Migrating data based on wordline information using a memory sub-system controller to determine data movement between single-level cell (SLC) and multi-level cell (XLC) memory portions, employing corrective program operations and utilizing adjacent wordline states to optimize data placement and reduce charge leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is stored in high-density multi-level cell memory, then storage capacity increases, but charge leakage increases and data retention deteriorates
Solution Approach 1:
The memory system is segmented into multiple memory portions with different cell types (SLC, MLC, TLC, QLC). The controller selectively stores data in appropriate portions based on retention requirements, separating data that requires high retention from data that can tolerate charge leakage, thus resolving the contradiction between high storage capacity and data retention.
Solution Approach 2:
Different memory portions are assigned different quality characteristics based on their cell type. SLC portions provide high retention for critical data, while XLC portions provide high capacity for less critical data. This local differentiation allows the system to achieve both high overall capacity and high data retention for appropriate data sets.
2Reliability
If data migration operations are performed frequently to maintain data retention, then data retention improves, but device complexity and operational overhead increase
Solution Approach 1:
The system performs preliminary actions by proactively migrating data to appropriate memory portions before charge leakage becomes problematic. The controller monitors retention characteristics and preemptively relocates data to SLC portions or other suitable portions, avoiding the need for frequent corrective migration operations and reducing overall system complexity.
Solution Approach 2:
The memory system serves itself by automatically monitoring retention status and performing data migration without external intervention. The controller manages the entire process of detecting retention issues and relocating data, reducing the need for complex external management systems and media scans.
3Reliability
If data is stored in single-level cell memory, then data retention improves, but storage capacity decreases
Solution Approach 1:
The memory device merges multiple memory portions with different cell types (SLC, MLC, TLC, QLC) into a unified storage system. This combination allows the system to achieve both high data retention (through SLC portions) and high storage capacity (through XLC portions), resolving the contradiction between retention and capacity that exists in individual memory types.
Solution Approach 2:
The memory system provides universal functionality by accommodating both high-retention SLC storage and high-capacity XLC storage within the same device. The controller intelligently directs different data sets to appropriate portions, making the system universally suitable for both retention-critical and capacity-critical applications.
Data Source
AI summary
Various aspects of the present disclosure relate to a memory sub-system for migrating data based on wordline information. A processing device received data from a host system and writes the data to a first memory portion of the memory device. The processing device determines to move at least a subset of data stored in the first memory portion of the memory device to a second memory portion of the memory device configured as multiple-level cell (XLC) memory, the subset of data being associated with a first wordline of the plurality of wordlines. The processing device obtains information associated with a second wordline of the plurality of wordlines, the second wordline being adjacent to the first wordline. The processing device performs a data migration operation, using the information associated with the second wordline, to move the subset of data from the first memory portion to the second memory portion.