Memory Block Defect Pattern Recovery for Higher Data Integrity
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Solution Overview
Problem
Memory devices with defective cells face challenges in efficiently storing and retrieving data due to the presence of cells that deviate significantly from intended target values, leading to programming errors and reduced storage capacity.
Innovation Solution
A method and system that identify patterns of defective memory cells in one group and apply these patterns to another group within the same block to recover data, using Error Correction Code (ECC) decoding and marking bits with low reliability, while also allocating excess memory for cell substitution and ECC redundancy based on identified defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If defective memory cells are identified and managed using traditional methods (individual cell remapping or sector remapping), then some data integrity is maintained, but storage capacity is significantly reduced and operational flexibility is limited
Solution Approach 1:
The memory block is segmented into multiple word lines, and defect patterns are identified at the word line level rather than individual cell level. This allows finer-grained management of defective cells while preserving more usable storage capacity by only affecting the specific word lines containing defects.
Solution Approach 2:
The defect pattern identified in one group of memory cells is applied universally to another group within the same block. This multi-functional approach allows a single defect identification process to protect multiple pages across different word lines, maximizing the utility of defect information and improving both reliability and storage capacity utilization.
2Reliability
If traditional defect management methods are used, then some data protection is achieved, but the complexity of defect tracking and remapping increases
Solution Approach 1:
Defect patterns are identified and stored in advance during a test phase or initial operation, before actual data storage begins. This preliminary defect characterization allows the system to automatically handle defects during normal operation without complex real-time detection, reducing operational complexity while maintaining strong data protection.
Solution Approach 2:
Instead of tracking each defective cell individually, the system creates a defect pattern model that can be copied and applied across multiple word lines. This pattern-based approach simplifies defect tracking by using a compact representation that can be reused universally within the block, significantly reducing the complexity of defect management.
3Quantity of substance
If no defect management is implemented, then storage capacity is maximized, but error probabilities increase significantly
Solution Approach 1:
The system applies defect management selectively only to the specific word lines and pages that contain defective cells, rather than managing the entire memory block. This localized approach minimizes the impact on overall storage capacity while providing targeted protection against errors in affected areas, maintaining high reliability without significant capacity loss.
Data Source
AI summary
A method for data storage in a memory including multiple memory cells arranged in blocks, includes storing first and second pages in respective first and second groups of the memory cells within a given block of the memory. A pattern of respective positions of one or more defective memory cells is identified in the first group. The second page is recovered by applying the pattern identified in the first group to the second group of the memory cells.