CMOS Image Sensor Color Filter Layout for Phase Detection
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Solution Overview
Problem
The challenge in manufacturing CMOS image sensors is the difficulty in producing smaller pixels while maintaining the complexity of color filters, which affects the image resolution and manufacturing process.
Innovation Solution
The proposed solution involves an image sensor with a pixel array and a color filter array, where the color filters are arranged in an M×N matrix, allowing for efficient phase detection and image processing without the need for color filters on phase detection pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to achieve high-resolution images, then the image resolution is improved, but the manufacturing difficulty of the color filter array increases
Solution Approach 1:
The color filter array is divided into multiple unit groups, where each unit group contains a specific arrangement of color filters (e.g., two green filters, one red filter, one blue filter). This segmentation allows for standardized manufacturing modules that can be repeatedly produced, reducing the overall manufacturing difficulty while maintaining high pixel density for high-resolution imaging.
Solution Approach 2:
Different regions of the color filter array are designed with specific local characteristics. Unit groups are strategically placed in different areas, with each unit group containing color filters arranged to optimize local phase detection and image quality. This local optimization approach allows the overall system to achieve high resolution while managing manufacturing complexity through localized standardized designs.
2Device complexity
If phase detection pixels and normal pixels are integrated in the same color filter array, then the device complexity is reduced, but the manufacturing precision required increases
Solution Approach 1:
Phase detection pixels and normal pixels are merged into a single color filter array structure, eliminating the need for separate arrays. Each unit group contains both types of pixels with appropriately assigned color filters, reducing device complexity by integrating multiple functions into one unified structure while maintaining manufacturability through standardized unit group designs.
Solution Approach 2:
The color filter array is pre-configured with unit groups that have predetermined color filter arrangements optimized for both phase detection and normal imaging functions. This preliminary design of standardized units allows manufacturing processes to follow established patterns, reducing the precision requirements compared to customizing each pixel location individually.
3Measurement precision
If color filters of the same color are arranged in an M×N matrix in unit groups, then the phase detection accuracy is improved, but the color filter array complexity increases
Solution Approach 1:
The color filter array is segmented into repeating unit groups, where each unit group contains a specific M×N matrix arrangement of color filters (e.g., 2×2 or 3×3 matrices with specific color distributions). This segmentation creates manageable standardized modules that improve phase detection accuracy through consistent local arrangements while reducing overall structural complexity through repetition.
Solution Approach 2:
The color filter array uses variations in the M×N matrix parameters (different sizes, different color filter distributions within matrices) to optimize phase detection accuracy for different regions or applications. By changing these parameters in a controlled manner across unit groups, the system achieves high detection accuracy without requiring a completely complex unique design for each region.
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
This configuration reduces the manufacturing complexity of the image sensor, enables accurate phase detection, and improves image resolution by allowing for smaller pixel sizes without compromising the color filter array's functionality.
Implementation Method 1
An image sensor is a semiconductor device that converts optical information into an electrical signal. The image sensor may include a charge coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor. A pixel array constituting a CMOS image sensor includes a photoelectric conversion element for each pixel. The photoelectric conversion device may generate an electrical signal that varies according to the amount of incident light
Data Source
AI summary
An image sensor includes a pixel array including a plurality of normal pixels, a plurality of phase detection groups, and a color filter array. Each phase detection group includes a first phase detection pixel and a second phase detection pixel disposed adjacent to the first phase detection pixel. The color filter array includes a plurality of unit groups. Each unit group includes a plurality of color filters of a same color arranged in an M×N matrix on the pixel array, wherein M and N are natural numbers. A first color filter among the color filters of a first color is disposed on the first phase detection pixel of one of the unit groups and a second color filter among the color filters of a second color different from the first color is disposed on the second phase detection pixel of another one of the unit groups.