Stacked Visible-IR Pixel Structure for Infrared Light Reception
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Solution Overview
Problem
Existing image sensors face challenges in effectively receiving light in the infrared band due to reduced light incidence caused by wiring density on the incident surface for visible light sensors, and materials used for visible light wiring often transmit infrared light inefficiently.
Innovation Solution
A solid-state imaging device is designed with a first pixel for visible light and a second pixel stacked on top, separated by a wiring layer and an infrared light transmission filter, which includes materials like amorphous silicon and silicon dioxide, transition metal dichalcogenides, or indium phosphorus to allow efficient infrared light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stacked configuration is used to acquire both visible light and infrared light information, then multi-band imaging capability is improved, but light reception efficiency in the infrared band deteriorates due to wiring density blocking incident light
Solution Approach 1:
An infrared light transmission filter is introduced as an intermediary component between the visible light pixel and the infrared light pixel. This filter selectively transmits infrared light while blocking visible light, enabling the infrared pixel to receive sufficient infrared light without interference from the visible light wiring structure above it.
Solution Approach 2:
The patent applies different optical properties to different regions of the device. The infrared light transmission filter is specifically positioned and designed to have high transmittance in the infrared wavelength range while maintaining blocking capability in the visible range, creating localized optical quality optimization for the infrared pixel region.
2Reliability
If metal wiring is used for visible light pixel signal transmission, then electrical conductivity is improved, but infrared light transmission efficiency deteriorates because metal materials block infrared light
Solution Approach 1:
The patent employs a composite structure combining metal wiring for electrical signal transmission with an infrared light transmission filter made of dielectric materials. This composite approach allows the metal wiring to fulfill its electrical function while the filter layer compensates for the infrared blocking effect, enabling both reliable signal transmission and efficient infrared light transmission.
3Illumination intensity
If polysilicon material is used for wiring, then infrared light transmission is improved compared to metal, but visible light transmission increases causing interference with infrared pixel
Solution Approach 1:
The infrared light transmission filter serves as a mediator that allows polysilicon wiring to transmit infrared light effectively while the filter blocks the visible light that would otherwise pass through the polysilicon and interfere with the infrared pixel's operation.
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
The solution enables simultaneous imaging in both visible and infrared light bands by enhancing light reception in the infrared band without interference from the visible light wiring, improving the overall imaging capability of the device.
Implementation Method 1
The infrared light transmission filter may include a combination of a material having a characteristic of absorbing or reflecting light in a visible light band depending on a wavelength or a material having a characteristic of reflecting the light in the visible light band
Implementation Method 2
The second pixel is formed by being stacked with the first pixel, and receives light in an infrared light band transmitted through the first pixel
Data Source
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AI summary
To more appropriately receive light in an infrared light band. A solid-state imaging device includes a first pixel, a second pixel, a wiring layer, and an infrared light transmission filter. The first pixel receives light in a visible light band and generates a pixel signal in a visible light band. The second pixel is formed by being stacked with the first pixel, and receives light in an infrared light band transmitted through the first pixel and generates a pixel signal in an infrared light band. The wiring layer is formed between the first pixel and the second pixel and includes a wiring that propagates a signal output from the first pixel. The infrared light transmission filter includes an infrared light transmission filter on a light incident surface of the second pixel.