Self-Repairing Memory System with Soft and Hard Repair Sub-Circuits
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Solution Overview
Problem
Existing memory devices face costly replacements due to data loss, as they lack effective methods for repairing defective memory locations without external intervention or permanent alterations.
Innovation Solution
A self-repairing memory system that integrates redundant memory elements and a repair module capable of both soft and hard repairs, using fuses and anti-fuses to remap defective memory locations to redundant ones, allowing for reversible or permanent data path changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant memory elements are added to enable repair operations, then the reliability of the memory system is improved, but the device complexity increases
Solution Approach 1:
The memory array is segmented into functional memory elements and separate redundant memory elements. The repair module identifies defective locations and remaps them to corresponding redundant locations, allowing the system to maintain functionality while isolating the complexity of repair operations from the main memory structure.
Solution Approach 2:
A repair module is introduced as an intermediary component between the memory array and the control logic. This module handles the complexity of defect detection, location identification, and remapping operations, shielding the rest of the system from the complexity of memory repair while improving overall reliability.
2Reliability
If hard repair operations using fuses are implemented, then the reliability of data storage is improved, but the ease of repair deteriorates due to permanent alterations
Solution Approach 1:
The repair system provides dynamic choices between soft repair (reversible remapping) and hard repair (permanent fuse programming) based on the specific defect conditions and system requirements. This allows the system to adapt the repair method to minimize permanent alterations while ensuring data storage reliability.
Solution Approach 2:
The system changes the state of repair from permanent (hard repair with fuses) to reversible (soft repair with remapping) based on operational parameters. The repair module can select different repair modes depending on whether permanent alteration is necessary, thereby balancing reliability requirements with repair flexibility.
3Ease of repair
If soft repair operations are used for reversible remapping, then the ease of repair is improved, but the reliability of permanent data retention deteriorates
Solution Approach 1:
The system dynamically selects between soft and hard repair modes based on the defect characteristics and operational requirements. Soft repair is used when reversibility is needed, while hard repair is applied when permanent data retention is critical, thereby resolving the contradiction between ease of repair and reliability.
4Productivity
If memory repair operations are performed during manufacturing, then the productivity is improved, but the device complexity increases due to additional test and repair circuits
Solution Approach 1:
The repair module is merged with the existing memory control logic and test circuits, combining defect detection, location identification, and remapping operations into an integrated system. This reduces the overall complexity addition during manufacturing while maintaining high productivity through automated repair operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the repair of defective memory devices during manufacturing, post-manufacturing, and in-use scenarios, extending the lifespan of memory devices and reducing replacement costs by utilizing built-in self-test and programmable circuits for on-the-fly memory remapping.
Implementation Method 1
The memory repair device 64 blows one or more of the fuses 63 (i.e. applies a laser or electrical current to the fuses 63) to form a new data path to the redundant location
Implementation Method 2
The memory repair sub-circuit 65 programs the redundant address rows 58 and address columns 60 to correspond to a specific memory address when a bit location associated with a memory address is found to be defective
Data Source
AI summary
A self-repairing memory system includes memory including memory elements and redundant memory elements. The memory elements include a plurality of memory cells. A memory repair module identifies non-operational memory cells and selects at least one memory element including the non-operational memory cells. A first repair sub-circuit soft repairs the memory by substituting the selected memory elements with the redundant memory elements. A second repair sub-circuit hard repairs the memory based on the substitutions.