Image Sensor Redundancy Circuit for Defective Logic Block Replacement
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Solution Overview
Problem
Current methods for fabricating CMOS image sensors are complex and expensive, and stacked image sensors face yield issues due to defective logic blocks in the peripheral circuit, leading to reduced production efficiency.
Innovation Solution
Incorporating a redundancy block system within the peripheral circuit of image sensors, where a repair circuit selects between logic blocks and redundancy blocks based on test results, using one-time programmable memory or fuse blocks for defective block storage and replacement, allowing for efficient defect replacement and improved yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If current methods for fabricating CMOS image sensors are used, then manufacturing capability is maintained, but the process becomes complicated and expensive
Solution Approach 1:
The patent segments the peripheral circuit into multiple independent logic blocks (first logic block, second logic block, third logic block) with corresponding redundancy blocks. This segmentation allows independent testing and replacement of defective blocks, simplifying the overall fabrication and repair process while maintaining functional integrity.
Solution Approach 2:
The patent implements preliminary action by pre-configuring redundancy blocks and repair circuits during the fabrication process. The repair circuit is pre-programmed with replacement information in OTP memory, enabling automatic defect replacement without complex post-fabrication processing, thus reducing overall fabrication complexity.
2Productivity
If stacked image sensors are fabricated, then production efficiency is improved, but yield is reduced due to defective logic blocks
Solution Approach 1:
The patent applies beforehand cushioning by incorporating redundancy blocks that serve as backup components. When a logic block is found defective during testing, the repair circuit automatically activates the corresponding redundancy block, cushioning against yield loss and ensuring functional sensors are produced even with defective components.
Solution Approach 2:
The patent implements feedback through the repair circuit that receives test results from logic blocks and automatically activates corresponding redundancy blocks based on defective block information stored in OTP memory. This closed-loop feedback mechanism ensures defective sensors are identified and corrected, maintaining high production yield.
3Reliability
If redundancy blocks are incorporated in the peripheral circuit, then defective blocks can be replaced, but device complexity increases
Solution Approach 1:
The patent applies universality by designing redundancy blocks with the same structure and function as the original logic blocks. Each redundancy block can universally replace its corresponding logic block, and the repair circuit universally handles all replacement decisions, reducing the need for specialized components and simplifying the overall design.
Solution Approach 2:
The patent uses copying by creating redundancy blocks that are exact copies of the logic blocks they may replace. This copying approach ensures functional equivalence while maintaining design simplicity, as the redundancy blocks can be generated using the same design rules and fabrication processes as the original logic blocks.
Data Source
AI summary
An image sensor includes a pixel array and a peripheral circuit. The peripheral circuit is electrically connected to the pixel array and includes a logic block and at least one redundancy block to replace the logic block when the logic block is a defective block.