Fin-Like SPAD Junction Structure for Higher Photon Detection Resolution
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Solution Overview
Problem
Existing single-photon avalanche diode (SPAD) sensors have limitations in efficiency and resolution due to the limited area of the p-n junction, which affects their performance in applications like machine vision.
Innovation Solution
The formation of a p-n junction in fin-like structures with a wavy or non-planar configuration increases the area of the junction, enhancing the generation of photo-generated carriers and improving sensor efficiency and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a planar p-n junction is used, then the device structure is simple, but the junction area is limited which reduces sensor efficiency and resolution
Solution Approach 1:
The patent applies curvature by forming the p-n junction in fin-like structures with wavy or non-planar configurations instead of flat surfaces. This increases the effective junction area where photo-generated carriers are generated, directly improving sensor efficiency and resolution while maintaining a manufacturable structure through standard semiconductor processing techniques
Solution Approach 2:
The patent transitions from a two-dimensional planar junction to a three-dimensional fin-like structure with vertical components. This dimensional change allows the junction area to extend in the vertical dimension, significantly increasing the effective area for photon detection without proportionally increasing the lateral footprint of the device
2Productivity
If the p-n junction area is increased to improve efficiency, then sensor performance improves, but the device complexity increases
Solution Approach 1:
The wavy or non-planar configuration of the fin-like structures increases the junction area within a compact footprint, improving photo-generated carrier generation efficiency without requiring a proportional increase in device size or manufacturing complexity
Solution Approach 2:
The patent divides the sensor into multiple fin-like structures rather than using a single large planar junction. This segmentation allows the total junction area to be increased while maintaining manageable device dimensions and facilitating 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 increased p-n junction area in the fin-like structures leads to improved efficiency and resolution in SPAD sensors, particularly for machine vision applications.
Implementation Method 1
photo-generated carriers move to a depletion region (i.e., a multiplication junction region) of the p-n junction and trigger an avalanche effect such that a signal current is detected
Implementation Method 2
A SPAD is a photodiode including a p-n junction that operates at a reverse bias above a breakdown voltage. During operation, photo-generated carriers move to a depletion region and trigger an avalanche effect
Data Source
AI summary
A semiconductor structure including a SPAD sensor includes a plurality of fin-like structures disposed over a semiconductor substrate, a mesa surrounding the plurality of fin-like structures over the semiconductor substrate, a first well in the semiconductor substrate, a second well in each fin-like structure over the first well, and a doped layer disposed in the plurality of fin-like structures and over the second well.