Image Sensor TEG for Light-Shielding Misalignment Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensors face issues with image distortion due to misalignment of light-shielding structures, affecting output values and leading to defects, which current technologies have not adequately addressed.
Innovation Solution
Incorporating a test element group (TEG) with a test light-shielding pattern different from the active area's light-shielding pattern to detect misalignment, allowing for realignment and improving manufacturing yield and performance by using dummy pixels and an image signal processor for image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-shielding structure is formed around the photodiode to prevent image distortion, then image quality is improved, but misalignment of the light-shielding structure causes output value changes and defects
Solution Approach 1:
The patent applies preliminary action by forming a test light-shielding pattern on dummy pixels before final production. This test pattern allows alignment verification to be performed in advance, enabling correction of misalignment issues before the actual light-shielding structures on active pixels are finalized, thus preventing defects while maintaining manufacturing efficiency
Solution Approach 2:
The patent uses dummy pixels with test light-shielding patterns as an intermediary element. These dummy pixels serve as a mediator to detect and measure alignment accuracy between the light-shielding structure and photodiodes, providing a reference for alignment verification without affecting the functional active pixels
2Productivity
If misalignment detection is implemented to improve manufacturing yield, then production efficiency is improved, but additional test structures increase device complexity
Solution Approach 1:
The patent applies segmentation by separating the sensor array into functional active pixels and non-functional dummy pixels. The dummy pixels are dedicated solely to alignment testing purposes, allowing the test functionality to be segmented from the imaging functionality, thus enabling yield improvement without compromising the performance or increasing the complexity of the active imaging area
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
The solution enables accurate detection and correction of misalignment, enhancing the mass-production yield and performance of CMOS image sensors by using a TEG with a test light-shielding pattern to assess and adjust the light-shielding structure alignment.
Implementation Method 1
a signal charge generated in a photodiode is converted into a voltage
Data Source
AI summary
An image sensor, imaging device, and method are provided. The image sensor includes a pixel array including an active area in which plural active pixels are located, and a dummy area in which plural dummy pixels are located, and a test element group (TEG) which is located in the dummy area and on which a test light-shielding pattern, different from a light-shielding pattern formed on the active area, is formed to detect a degree of misalignment between the light-shielding pattern and the active area.