Avalanche Photodiode Pixel Structure to Suppress Edge Breakdown
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Solution Overview
Problem
Existing light detection devices face challenges in suppressing unintended edge breakdown, which limits their miniaturization and sensitivity, especially in distance measurement applications where precise light reception is crucial.
Innovation Solution
A light detection device is designed with a semiconductor layer on the first surface of a semiconductor substrate, where the n-type semiconductor region of the multiplier is embedded in the semiconductor layer, ensuring a controlled distance between electrodes and reducing impurity diffusion, thereby suppressing edge breakdown and enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor region is provided to surround the avalanche photodiode for pixel isolation, then pixel isolation is improved, but edge breakdown occurs at the boundaries
Solution Approach 1:
The patent transitions from two-dimensional planar pixel isolation to three-dimensional stacked structure by placing the light receiver and multiplier in different vertical layers. The light receiver is positioned in a first semiconductor layer while the multiplier is in a second semiconductor layer, achieving pixel isolation and preventing edge breakdown through vertical separation rather than lateral surrounding structures.
Solution Approach 2:
The pixel structure is segmented into multiple functional layers: a light receiver layer containing the photodiode and a separate multiplier layer containing the avalanche multiplication region. This segmentation allows each component to be optimized independently and eliminates the harmful interaction at the boundaries between adjacent pixels by separating the high-field regions.
2Area of moving object
If the pixel size is reduced for miniaturization, then device integration is improved, but edge breakdown becomes more pronounced
Solution Approach 1:
By moving to a three-dimensional stacked architecture where the light receiver and multiplier are vertically separated into different layers, the patent enables smaller pixel footprints without increasing the lateral extent of high-field regions. This vertical integration allows miniaturization of the pixel area while maintaining adequate separation between electrically active regions to prevent edge breakdown.
3Length of stationary object
If the distance between the light receiver and multiplier is reduced for compactness, then device area is improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent achieves compact integration by placing the light receiver and multiplier in vertically stacked layers with a controlled vertical separation distance. This vertical arrangement allows precise control of the interaction distance through layer thickness design while maintaining adequate separation to prevent edge breakdown, offering better manufacturing control compared to lateral positioning in the same plane.
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 effectively suppresses unintended edge breakdown and improves sensitivity by ensuring a controlled distance between electrodes, allowing for more accurate light reception and better performance in distance measurement applications.
Implementation Method 1
a light receiver that is provided inside the semiconductor substrate for each of the pixels, and generates carriers corresponding to a received light amount by photoelectric conversion
Implementation Method 2
a multiplier that includes a first conduction-type region and a second conduction-type region sequentially stacked on the side of the first surface, at least the second conduction-type region being provided in the semiconductor layer, and that performs avalanche multiplication on the carriers generated by the light receiver
Data Source
AI summary
A light detection device according to an embodiment of the present disclosure includes: a semiconductor substrate that includes a first surface and a second surface opposed to each other, and includes a pixel array in which a plurality of pixels is disposed in an array; a semiconductor layer that is provided on a side of the first surface of the semiconductor substrate; a light receiver that is provided inside the semiconductor substrate for each of the pixels, and generates carriers corresponding to a received light amount by photoelectric conversion; a multiplier that includes a first conduction-type region and a second conduction-type region sequentially stacked on the side of the first surface, at least the second conduction-type region being provided in the semiconductor layer, and that performs avalanche multiplication on the carriers generated by the light receiver; a first electrode that is provided on the side of the first surface, and is electrically coupled to the light receiver; and a second electrode that is provided on the side of the first surface, and is electrically coupled to the multiplier.