Photoelectric Conversion Reflector Stack for Higher APD Sensitivity
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Solution Overview
Problem
Existing photoelectric conversion devices with avalanche photodiodes (APDs) face complexity in design due to the need for reflective metal layers and contact plugs, which complicates the structure and may not efficiently improve sensitivity.
Innovation Solution
A photoelectric conversion device with a semiconductor layer, a wiring structure, and a contact plug, where a light reflecting layer with a periodic structure of dielectric and semiconductor layers is arranged between the wiring layer and the semiconductor layer, allowing the contact plug to penetrate and improving sensitivity without increasing structural complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflective metal layer is arranged to overlap the APD in a wiring structure, then the sensitivity can be improved by reflecting light that has not been fully absorbed by a semiconductor layer to the semiconductor layer, but the design becomes complicated due to the need to arrange the reflective metal layer and contact plug taking into consideration the breakdown voltage between the reflective metal layer and the contact plug
Solution Approach 1:
The patent changes the material parameter from metal to dielectric for the reflective layer, and changes the structural parameter from solid to periodic multilayer. This allows the layer to maintain high reflectivity while being electrically non-conductive, thus improving sensitivity without complicating the design with breakdown voltage considerations
Solution Approach 2:
The patent uses a composite periodic structure consisting of multiple dielectric layers with different refractive indices (high-refractive-index layer and low-refractive-index layer). This composite structure achieves superior optical reflection properties compared to single-material layers, enabling high sensitivity improvement while maintaining design simplicity
2Loss of energy
If a reflective metal layer is arranged between the wiring layer and the semiconductor layer, then light reflection efficiency is improved, but the structural complexity increases due to the need to ensure breakdown voltage between the reflective metal layer and other components
Solution Approach 1:
The patent replaces the expensive and problematic metal reflective layer with a dielectric periodic structure that is easier to manufacture and integrates more simply with existing semiconductor processes. The dielectric layers can be formed using standard deposition techniques, reducing structural complexity
Solution Approach 2:
The periodic dielectric structure acts as an intermediary between the wiring layer and semiconductor layer, providing optical reflection functionality without the electrical conductivity issues of metal. This intermediary structure achieves high reflection efficiency while avoiding breakdown voltage problems
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 proposed solution enhances the sensitivity of the photoelectric conversion device by effectively reflecting unabsorbed light back into the semiconductor layer, thereby improving performance without complicating the device structure.
Implementation Method 1
a light reflecting layer through which the contact plug penetrate is arranged between the wiring layer and the semiconductor layer, and the light reflecting layer has a periodic structure in which a first layer constituted by one of a dielectric and a semiconductor and a second layer constituted by one of a dielectric and a semiconductor that are different from the first layer are periodically stacked
Data Source
AI summary
A photoelectric conversion device is provided. The device includes: a semiconductor layer having a photoelectric conversion element; a wiring structure; and contact plug that connect the semiconductor layer and a wiring pattern arranged in a wiring layer closest to the semiconductor layer among wiring layers included in the wiring structure. A light reflecting layer through which the contact plug penetrate is arranged between the wiring layer and the semiconductor layer, and the light reflecting layer has a periodic structure in which a first layer constituted by one of a dielectric and a semiconductor and a second layer constituted by one of a dielectric and a semiconductor that are different from the first layer are periodically stacked.