Memory Codeword Switching for Fail-Prone ECC Areas
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Solution Overview
Problem
Volatile memory devices face increased failure possibilities during manufacturing or use, necessitating improved error correction capabilities in areas prone to failures, especially when traditional Error Correction Codes (ECC) cannot correct codeword failures.
Innovation Solution
A memory device and method that convert first codewords of a first type to second codewords of a higher error correction capability type in memory areas likely to fail, using a controller to identify and convert codewords in fail memory units, and employ distinct error detection and correction circuits for each codeword type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Error Correction Code (ECC) is used for error correction in volatile memory, then the manufacturing process is simple and device complexity is low, but error correction capability is insufficient in areas prone to failures
Solution Approach 1:
The patent applies local quality by differentiating error correction approaches for different memory areas. Specifically, memory areas are classified into first types (without fail memory units) and second types (with fail memory units), and different codeword types are stored in each area. This allows the system to enhance error correction capability locally in prone areas while maintaining simplicity in reliable areas, thus resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The patent segments the memory device into multiple memory areas based on the presence of fail memory units. By dividing the memory into first memory areas (using first codewords) and second memory areas (using second codewords with higher error correction capability), the system can selectively apply enhanced error correction only where needed, improving overall reliability without uniformly increasing device complexity across the entire memory device.
2Reliability
If codeword conversion is performed in memory areas with fail memory units, then error correction capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements preliminary action by performing codeword conversion in advance during the manufacturing process or initial operation phase. The controller identifies fail memory units and converts first codewords to second codewords with higher error correction capability before actual data usage. This preliminary conversion ensures that memory areas with manufacturing defects are pre-configured with enhanced error correction, improving reliability without requiring higher manufacturing precision during normal operation.
3Reliability
If distinct error detection and correction circuits are used for different codeword types, then error correction performance is enhanced, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing distinct error detection and correction circuits only for specific memory areas where needed. First error detection and correction circuits are used for first codewords in reliable memory areas, while second error detection and correction circuits with higher performance are used for second codewords in memory areas with fail memory units. This localized differentiation enhances error correction performance in prone areas while avoiding unnecessary complexity in reliable areas.
Data Source
AI summary
A memory device includes a memory media including a plurality of memory units and a controller configured to set a plurality of memory areas, each of the plurality of memory areas including one or more of the plurality of memory units. The controller is configured to store one or more first codewords of a first type in a target memory area among the plurality of memory areas, search for a fail memory unit among the memory units included in the target memory area, and when the fail memory unit is searched, convert one or more of the first codewords into a second codeword having a second type and write the converted second codeword to the memory media.