Lateral Avalanche Photodiode for 3D Integration
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Solution Overview
Problem
Existing avalanche photodiode devices are not well-suited for three-dimensional integration, which limits their application in advanced imaging and detection technologies.
Innovation Solution
A lateral avalanche photodiode device is designed with a semiconductor substrate featuring trenches and doped regions of opposite conductivity types, allowing for efficient avalanche multiplication and integration with electronic components, enabling three-dimensional integration and high quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If vertical avalanche photodiode devices are used, then satisfactory gain can be obtained at relatively low operation voltage, but they are not well-suited for three-dimensional integration
Solution Approach 1:
The patent transitions from a vertical photodiode structure to a lateral structure where the avalanche multiplication region is positioned horizontally adjacent to the absorption region. This dimensional reconfiguration enables three-dimensional integration by allowing electronic components to be stacked above and below the photodiode active areas, as the charge carrier collection paths are separated in the lateral direction rather than requiring vertical stacking.
2Adaptability or versatility
If the avalanche multiplication region is separated from the absorption region, then three-dimensional integration is enabled, but device structure becomes more complex
Solution Approach 1:
The photodiode is segmented into distinct functional regions: an absorption region for photon detection and a laterally-separated avalanche multiplication region for gain. These regions are electrically connected through doped contact regions that guide charge carriers. This segmentation allows independent optimization of each region and enables three-dimensional integration while maintaining manageable structural complexity through clear functional separation.
Solution Approach 2:
Doped contact regions serve as intermediaries between the absorption region and the avalanche multiplication region. These contact regions facilitate the lateral transport of charge carriers between the separated functional areas, enabling the divided structure to operate as a unified device while supporting three-dimensional integration architecture.
3Productivity
If a lateral structure is used for three-dimensional integration, then integration density increases, but manufacturing precision requirements increase
Solution Approach 1:
The absorption region, avalanche multiplication region, and contact regions are formed through a sequence of preliminary doping steps during semiconductor fabrication. By establishing the doping profiles and spatial relationships between regions in advance through controlled diffusion or implantation processes, the lateral structure achieves the required alignment precision while enabling high integration density for three-dimensional stacking.
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 lateral avalanche photodiode device achieves high quantum efficiency and large absorption and multiplication volumes, with electric field strength independent of substrate thickness, facilitating its use in advanced imaging and detection applications.
Implementation Method 1
The operation of an avalanche photodiode is based on the conversion of photon energy into free charge carriers
Implementation Method 2
their further avalanche multiplication via impact ionization in a region of very high electric field strength
Data Source
AI summary
A lateral avalanche photodiode device comprises a semiconductor substrate (1) having a trench (4) with side walls (5) extending from a main surface (2) to a rear surface (3). A first doped region (11) is present at the side walls of the trench, and a second doped region (12) is arranged at a distance from the first doped region. A third doped region (13) is located adjacent to the first doped region, extends through the substrate from the main surface to the rear surface, and is arranged between the first doped region and the second doped region. The third doped region (13) is the avalanche multiplication region of the photodiode structure. The second doped region and the third doped region have a first type of conductivity, and the first doped region has a second type of conductivity which is opposite to the first type of conductivity. The region of the substrate that is between the first doped region and the second doped region is of the first type of conductivity.