Ring-Shaped Photo-Detection Pixel for Depth Sensing
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Solution Overview
Problem
Three-dimensional image sensors have a lower signal-to-noise ratio and sensitivity compared to conventional two-dimensional image sensors, leading to inaccurate depth information when using infrared or near-infrared light.
Innovation Solution
A photo-detection device with unit pixels featuring a ring-shaped structure, including a floating diffusion region, a ring-shaped collection gate, and a ring-shaped drain gate, which efficiently collect and drain photo-charges, and a method using variable bin signals to improve signal-to-noise ratio and accurately measure distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional two-dimensional image sensor structure is used, then the structure is simple and manufacturing is easy, but the signal-to-noise ratio and sensitivity are lower
Solution Approach 1:
The pixel is divided into multiple functional regions including a photo-charge generating region, a photo-charge storing region, a floating diffusion region, and a drain region. This segmentation allows separate optimization of light reception, charge collection, and signal output functions, improving signal-to-noise ratio while maintaining manufacturing feasibility through standardized region definitions.
Solution Approach 2:
The patent transitions from a conventional planar two-dimensional sensor structure to a three-dimensional stacked structure with regions arranged vertically. The photo-charge generating region, storing region, floating diffusion region, and drain region are positioned at different depths, enabling improved charge collection efficiency and signal-to-noise ratio through vertical separation of functions.
2Adaptability or versatility
If infrared or near-infrared light is used for depth measurement, then three-dimensional imaging capability is achieved, but sensitivity and signal-to-noise ratio decrease
Solution Approach 1:
The patent implements a photo-charge storing region that accumulates photo-charges before they are transferred to the floating diffusion region for readout. This preliminary storage action allows integration of weak infrared/near-infrared signals over time, improving sensitivity and signal-to-noise ratio for depth measurement applications while maintaining the ability to capture three-dimensional information.
3Measurement precision
If photo-charges are not efficiently collected and drained, then the structure is simpler, but depth measurement precision is reduced
Solution Approach 1:
The patent introduces a floating diffusion region as an intermediary between the photo-charge storing region and the drain region. This intermediate structure enables efficient charge transfer and signal amplification, improving depth measurement precision by ensuring complete and controlled drainage of photo-charges while maintaining a manageable structural complexity through the use of standard semiconductor fabrication processes.
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 enhances the sensitivity and signal-to-noise ratio of the photo-detection device, enabling precise depth information acquisition by optimizing the collection and drainage of photo-charges and adjusting bin signal phases and duty ratios.
Implementation Method 1
converting received light corresponding to the emitted light into an electrical signal
Implementation Method 2
A collection gate signal and a drain gate signal may be applied to the collection gate and the drain gate, respectively, wherein photo-charges generated in the semiconductor substrate are collected in the floating diffusion region
Data Source
AI summary
A unit pixel included in a photo-detection device, the unit pixel including a floating diffusion region in a semiconductor substrate, a ring-shaped collection gate over the semiconductor substrate, a ring-shaped drain gate over the semiconductor substrate, and a drain region in the semiconductor substrate, wherein the collection gate and the drain gate are respectively arranged between the floating diffusion region and the drain region.