On-Chip IR Suppression Filter for Light Sensor Sensitivity
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Solution Overview
Problem
Existing light sensors face challenges in effectively filtering out infrared light while allowing visible light to reach photodetectors, leading to reduced sensitivity and limited spectral detection capabilities due to spacing constraints and external infrared blocking filters.
Innovation Solution
A light sensor design incorporating an IR suppression filter and color pass filters integrated on-chip, with a transparent substrate providing support and encapsulation, allowing for selective blocking of infrared light while passing visible light to photodetectors, and including clear photodetectors for ambient light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an external infrared blocking filter is used, then infrared light is blocked, but the device complexity increases and sensitivity is reduced due to spacing constraints
Solution Approach 1:
The patent combines the infrared blocking filter and color pass filters into a single integrated filter structure that is directly coupled to the photodetector array. This merging eliminates the need for separate external filters and reduces spacing requirements, thereby decreasing device complexity while maintaining effective infrared blocking capability.
Solution Approach 2:
The integrated filter structure nests multiple filtering functions (infrared blocking and color separation) within a single compact component. The filter is positioned in close proximity to the photodetector array, with different regions of the filter performing different spectral filtering functions, effectively nesting multiple functions in one structure.
2Object-affected harmful factors
If external infrared blocking filters are used, then infrared light is blocked, but sensitivity is reduced due to spacing constraints
Solution Approach 1:
By merging the infrared blocking function into the integrated filter structure that is directly coupled to the photodetector array, the patent eliminates spacing constraints that would otherwise reduce sensitivity. The close integration ensures maximum light collection efficiency while maintaining effective infrared blocking.
3Device complexity
If filters are integrated on-chip, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges the fabrication of filters and photodetectors into a single integrated process, which reduces overall device complexity. The integrated filter structure is fabricated using standard semiconductor manufacturing techniques, allowing for precise control of filter properties and positioning during the manufacturing process.
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
Enhances the sensitivity and spectral detection capabilities of light sensors by effectively blocking infrared light and allowing clear detection of visible light, improving performance in devices that rely on ambient light conditions.
Implementation Method 1
An IR suppression filter is positioned over the photodetectors. The IR suppression filter is configured to filter infrared light from light incident on the light sensor to at least substantially block infrared light from reaching the photodetectors.
Implementation Method 2
Typical light sensors employ photodetectors such as photodiodes, phototransistors, or the like, which convert received light into an electrical signal (e.g., a current or voltage).
Data Source
AI summary
Techniques are described to furnish an IR suppression filter, or any other interference based filter, that is formed on a transparent substrate to a light sensor. In one or more implementations, a light sensor includes a substrate having a surface. One or more photodetectors are formed in the substrate. The photodetectors are configured to detect light and provide a signal in response thereto. An IR suppression filter configured to block infrared light from reaching the surface is formed on a transparent substrate. The light sensor may also include a plurality of color pass filters disposed over the surface. The color pass filters are configured to filter visible light to pass light in a limited spectrum of wavelengths to the one or more photodetectors. A buffer layer is disposed over the surface and configured to encapsulate the plurality of color pass filters and adhesion layer.