Multi-Collection-Layer Photodiode for Wideband Light Detection
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Solution Overview
Problem
Conventional photodiodes have uniform light sensitivities, leading to overexposure issues in optical distance measuring devices and low photon detection efficiency due to challenges in attracting electrons in deep p-type substrates, which complicates IC design.
Innovation Solution
A photodiode with multiple collection layers using different semiconductor materials, including a first and second collection layer, type well layers, and semiconductor material connection layers, allowing for improved detection of near-infrared and short-wave infrared rays by absorbing light across a wider wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional image sensor with uniform light sensitivities is used, then the device structure is simple, but overexposure issues occur causing inaccurate distance computation
Solution Approach 1:
The image sensor is divided into multiple pixel types with different light sensitivities. Specifically, the sensor includes first pixels with first light sensitivities and second pixels with second light sensitivities, where the sensitivities differ between pixel types. This segmentation allows different regions to handle different light intensity scenarios, preventing overexposure while maintaining accurate distance computation.
2Reliability
If a p-type substrate is coupled to a negative voltage level to attract electrons, then photon detection efficiency improves, but IC design complexity increases
Solution Approach 1:
Instead of coupling the p-type substrate to a negative voltage level to attract electrons, the invention inverts the approach by coupling the n-type substrate to a positive voltage level. This achieves the same electron attraction effect but avoids the complexity of negative voltage coupling in IC design, as positive voltage coupling is more compatible with standard IC 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
Enhances photon detection efficiency and application range by effectively detecting light from 400 nm to 1700 nm, reducing overexposure issues and simplifying IC design by avoiding the need to couple p-type substrates to negative voltage levels.
Implementation Method 1
The first collection layer is formed in the substrate and doped with a first semiconductor material... The second collection layer is formed in the substrate and doped with a second semiconductor material... better performance in detecting near infrared (NIR) and short wave infrared (SWIR)
Data Source
AI summary
A photodiode comprises a substrate, a first collection layer, a first type well layer, a second type well layer and a second collection layer. The substrate has a first surface and a second surface. The substrate defines a bias region and a signal region. The first collection layer, the first type well layer, the first type well layer, the second type well layer, and the second collection layer are formed in the substrate. The first type well layer is disposed between the first surface and the first collection layer. The second type well layer is disposed between the first type well layer and the first collection layer. The second collection layer is located between the first surface and the second well layer.