Image Sensor Infrared Filter Fabrication
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Solution Overview
Problem
Conventional image sensors with infrared detection functions lack the necessary accuracy for effective infrared and visible light detection, leading to suboptimal performance in applications such as security and object detection.
Innovation Solution
A method of fabricating an image sensor involving the sequential formation of infrared filters and a color filter on a substrate, where the second infrared filter is lowered to expose the first, ensuring no gap between them, and a microlens layer is added for enhanced light sensitivity, allowing for precise detection of infrared and visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fabrication methods are used for image sensors with infrared detection, then the manufacturing process is simpler, but the image detection accuracy is insufficient
Solution Approach 1:
The fabrication process is segmented into distinct sequential steps: forming the first infrared filter on the substrate, depositing the second infrared filter over the first, selectively lowering the second infrared filter to expose the first, and forming the color filter on specific regions. This segmentation allows precise control over filter positioning and light detection accuracy while managing fabrication complexity through systematic process breakdown
Solution Approach 2:
Different regions of the substrate receive different filter configurations: the first region receives the first infrared filter for infrared detection, while the second region receives both infrared filters and a color filter for visible light detection. This local differentiation enables optimized detection accuracy for different wavelength ranges without requiring uniform complex structures across the entire sensor
2Reliability
If multiple infrared filters are formed sequentially with lowering process, then the light sensitivity and detection accuracy are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The first infrared filter is formed on the substrate before the second infrared filter is deposited. This preliminary action establishes a reference structure that guides subsequent deposition and lowering operations, ensuring proper alignment and positioning of the second filter relative to the first, thereby managing manufacturing precision requirements
Solution Approach 2:
The second infrared filter is lowered in the vertical dimension to expose the first infrared filter, creating a stepped configuration. This dimensional change allows both filters to coexist in the optical path without requiring complex lateral alignment, as the vertical positioning naturally defines the exposure regions for each filter type
3Measurement precision
If the second infrared filter is lowered to expose the first, then continuous coverage is achieved without gaps, but the fabrication process complexity increases
Solution Approach 1:
The lowering of the second infrared filter merges the coverage areas of both filters: the first filter covers the first region for infrared detection, while the lowered second filter covers the second region and neighbors the first filter. This merging achieves continuous coverage without gaps, ensuring that the entire substrate surface is protected and functional regions are properly defined
Solution Approach 2:
The lowering process acts as an intermediary step that reconciles the need for both filters to be present while avoiding gaps. By selectively removing material from the second filter in specific regions, the process mediates between the conflicting requirements of maintaining filter integrity and achieving continuous coverage, with the planarization layer serving as an intermediary structure to enable subsequent color filter formation
Data Source
AI summary
A method of fabricating an image sensor includes the following steps. A substrate is provided. A first infrared filter is formed on a first region of the substrate. A second infrared filter is deposited on the substrate and the first infrared filter. The deposited second infrared filter covers the first infrared filter. The second infrared filter is lowered to expose the first infrared filter. The lowered second infrared filter is on a second region of the substrate and neighbors the first infrared filter.