Image Sensor Structure with Backside Infrared Absorption Enhancer
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Solution Overview
Problem
Conventional image sensors with infrared detection capabilities face challenges in effectively distinguishing between visible and infrared light, leading to reduced quantum efficiency and increased crosstalk between different light detection regions.
Innovation Solution
The image sensor structure incorporates a semiconductor substrate with photo sensing members, an infrared absorption enhancing member, a color filter, an infrared pass filter, and microlenses, where the infrared absorption enhancing member is placed on the backside of the substrate in the infrared detection region, and the color filter is over the infrared pass filter, allowing for enhanced infrared light detection while maintaining visible light detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional image sensors are used for infrared detection, then infrared detection capability is achieved, but quantum efficiency is reduced and crosstalk between detection regions increases
Solution Approach 1:
The image sensor divides the detection regions into distinct segments with different optical filtering characteristics. The first detection region (visible light) is equipped with a color filter, while the second detection region (infrared) uses an infrared pass filter. This segmentation allows each region to be optimized for its specific wavelength range, improving quantum efficiency for both visible and infrared detection while reducing crosstalk between regions.
2Reliability
If conventional image sensors are used for infrared detection, then infrared detection capability is achieved, but crosstalk between detection regions increases
Solution Approach 1:
Different optical filtering properties are applied to different local regions of the image sensor. The color filter in the visible light detection region blocks infrared wavelengths, while the infrared pass filter in the infrared detection region allows infrared wavelengths to pass through. This local differentiation of optical properties enables effective crosstalk reduction while maintaining specialized detection capabilities in each region.
3Measurement precision
If filters are added to distinguish visible and infrared light, then light separation is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple filtering functions into a unified filter assembly that includes both the color filter and infrared pass filter positioned in close proximity. This merged structure allows simultaneous wavelength separation for both visible and infrared regions without requiring separate, complex filtering systems for each detection region, thereby reducing overall device complexity while maintaining effective light separation.
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 significantly improves quantum efficiency in the infrared detection region by 2-3 times at specific wavelengths, while maintaining unchanged quantum efficiency in the visible light detection regions, and reduces crosstalk between different light components, enabling better separation and processing of infrared and visible light signals.
Implementation Method 1
an infrared absorption enhancing member, where the infrared absorption enhancing member is placed on the backside of the substrate in the infrared detection region
Implementation Method 2
an infrared pass filter, having a wavelength pass band in a range from 700 nm to 1100 nm
Implementation Method 3
a color filter, where the color filter is over the infrared pass filter
Implementation Method 4
photo sensing members, wherein the photo sensing members are disposed in the front side of the semiconductor substrate
Implementation Method 5
microlenses, wherein the microlenses are respectively over the color filter and the infrared pass filter
Data Source
AI summary
An image sensor structure has a visible light detection region and an infrared light detection region neighboring the visible light detection region. The image sensor structure includes a semiconductor substrate, photo sensing members, an infrared absorption enhancing member, a color filter and an infrared pass filter. The semiconductor substrate has a front side and a back side opposite to each other. The first photo sensing member is disposed in the front side of the semiconductor substrate. The infrared absorption enhancing member is in the back side of the semiconductor substrate and only in the infrared light detection region. The color filter is over the back side of the semiconductor substrate and in the visible light detection region. The infrared pass filter is over the infrared absorption enhancing member.