Pixel Color Filter Layout for Visible and IR Image Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image sensing devices face challenges in improving sensitivity in the visible light region and quantum efficiency in the infrared region, particularly in low illuminance conditions, which are exacerbated by issues such as crosstalk.
Innovation Solution
The image sensing device incorporates a pixel array with a planarization layer, color filters, and trench structures of varying depths for each color, along with a microlens and device isolation regions, to enhance light focusing and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional color filters are used in image sensing devices, then the device can capture visible light, but the sensitivity in the visible light region and quantum efficiency in the infrared region deteriorate
Solution Approach 1:
The pixel array is divided into multiple types of pixels (first, second, third, and fourth pixels) with different color filter configurations. The first pixel uses a first color filter, the second pixel uses a second color filter, the third pixel uses a third color filter, and the fourth pixel uses a fourth color filter. This segmentation allows each pixel type to be optimized for specific wavelength regions, thereby improving overall sensitivity and quantum efficiency across visible and infrared spectra.
Solution Approach 2:
Different color filters are applied to different pixels based on their specific functional requirements. The first color filter is designed for specific visible light wavelengths, while the fourth color filter is optimized for infrared region detection. This local quality approach ensures that each pixel region has the optimal filter characteristics for its intended detection purpose, maximizing sensitivity in both visible and infrared regions.
2Reliability
If deeper trenches are used to reduce crosstalk, then crosstalk between adjacent pixels is reduced, but the manufacturing complexity and difficulty increase
Solution Approach 1:
The isolation structure is segmented into multiple trench types: first trenches extending from the first color filter to the substrate, second trenches extending from the second color filter to the substrate, third trenches extending from the third color filter to the substrate, and fourth trenches extending from the fourth color filter to the substrate. This segmentation allows each trench to be precisely positioned and depth-controlled for its specific pixel type, reducing crosstalk while maintaining manufacturability through standardized trench formation processes for each pixel category.
Solution Approach 2:
The color filters serve as intermediary structures that extend into the trenches, providing both optical filtering and mechanical support. The filters act as mediators between the substrate and the microlens structures, enabling effective crosstalk isolation while maintaining precise alignment and reducing the need for extremely deep trenches alone.
3Adaptability or versatility
If multiple color filters with different materials are used, then the spectral detection range is expanded, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The color filter system is segmented into four distinct filter types, each with specific material compositions optimized for different spectral regions. The first color filter uses materials optimized for visible light detection, while the fourth color filter uses materials optimized for infrared detection. This segmentation enables broad spectral coverage while allowing each filter type to be manufactured using specialized processes tailored to its specific optical requirements.
Solution Approach 2:
The color filters are constructed using composite material structures that combine multiple layers and materials with different optical properties. Each color filter integrates materials that provide both visible and infrared transmission or blocking characteristics, enabling multi-spectral detection capabilities within a unified filter structure that simplifies manufacturing compared to separate filters.
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 improves sensitivity in the visible light region and quantum efficiency in the infrared region, particularly at 850 nm, by optimizing light detection and reducing unwanted noise.
Implementation Method 1
a microlens and device isolation regions, to enhance light focusing
Implementation Method 2
the color filter is configured to filter incident light to be detected by the unit pixel
Implementation Method 3
a substrate supporting a photosensing element for the unit pixel
Data Source
AI summary
The present disclosure relates to an image sensing device including a pixel array including a plurality of unit pixels is arranged. Each of the plurality of unit pixels includes: a substrate; a planarization layer formed over the substrate; and a color filter disposed over the planarization layer. The color filter includes at least one of a white color filter, a green color filter, a blue color filter, or a red color filter. The planarization layer includes a material of the white color filter.