Compressed Repair Codes for Non-Volatile Memory Scaling
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Solution Overview
Problem
Existing implementations of non-volatile memory systems for memory repair, such as FuseROM, do not scale well with increasing device densities and decreasing device sizes, leading to inefficient use of memory space due to fixed repair code lengths and unused padding bits.
Innovation Solution
A system and method for compressing and decompressing repair codes using a non-volatile memory controller and logic that assigns compression parameters based on memory instance configurations, storing only useful bits and adding compression control data to reduce storage requirements, allowing for lossless compression and incremental memory repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-length repair codes are stored in non-volatile memory, then memory repair functionality is provided, but storage space is wasted due to unused padding bits
Solution Approach 1:
The patent changes the parameter of repair code length from fixed to variable based on actual defect patterns. Compression parameters are applied to reduce the number of bits needed to represent repair codes, storing only the necessary portion rather than always using the maximum fixed length, thereby reducing storage space while maintaining repair functionality
Solution Approach 2:
The patent extracts and stores only the essential repair code bits that are actually needed for a given memory instance, separating the useful information from the padding bits. By identifying and storing only the minimum required repair signature bits, the system eliminates wasted storage space while preserving the core repair functionality
2Adaptability or versatility
If non-volatile memory size is increased to accommodate all repair codes, then all memory instances can be repaired, but device area increases
Solution Approach 1:
The patent applies compression parameters to reduce the size of stored repair codes, allowing the same non-volatile memory area to accommodate repair codes for more memory instances. This effectively increases the repair coverage capability without physically expanding the non-volatile memory or device area
Solution Approach 2:
The patent segments the repair code storage into compressed portions, organizing repair data efficiently within the available non-volatile memory space. This segmentation allows maximum utilization of the fixed memory area to support a larger number of memory instance repairs
3Quantity of substance
If compression is applied to repair codes, then storage efficiency improves, but system complexity increases due to compression and decompression operations
Solution Approach 1:
The patent implements self-service compression where the system automatically determines the appropriate compression parameters and performs compression/decompression operations without external intervention. The control wrapper and non-volatile memory controller work autonomously to manage the compressed repair data, reducing the need for complex external control logic
Data Source
AI summary
One example includes an integrated circuit (IC). The IC includes non-volatile memory and logic. The logic is configured to receive repair code associated with a memory instance and assign a compression parameter to the repair code based on a configuration of the memory instance. The logic is also configured to compress the repair code based on the compression parameter to produce compressed repair code and to provide compressed repair data that includes the compressed repair code and compression control data that identifies the compression parameter. A non-volatile memory controller is coupled between the non-volatile memory and the logic. The non-volatile memory controller is configured to transfer the compressed repair data to and/or from the non-volatile memory.