Back-Surface Light-Receiving Device Submount Size Reduction
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Solution Overview
Problem
Back-surface-incident type light-receiving devices face challenges with increased submount size due to wire pattern formation and high-frequency reflection points from Au wires connecting circuit components, leading to reduced reception sensitivity.
Innovation Solution
The device features anode and cathode pads on the back surface of the substrate, with connecting holes allowing direct wire formation, eliminating the need for submount patterns and reducing high-frequency reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anodes and cathodes are formed on the front surface and connected via wires to metal patterns on the submount, then electrical connection is achieved, but the submount size increases
Solution Approach 1:
The patent inverts the conventional arrangement by forming the anode and cathode pads on the back surface of the substrate instead of the front surface. This allows wires to be directly connected to the light-receiving device from the back, eliminating the need for metal patterns on the submount and thereby reducing submount size while maintaining reliable electrical connection.
2Reliability
If Au wires connect circuit components with the light-receiving device, then electrical connection is achieved, but high-frequency reflection points increase causing resonance and reduced reception sensitivity
Solution Approach 1:
The patent extracts the problematic wire connections from the front surface area where they would create high-frequency reflection points. By moving the anode and cathode pads to the back surface, the wires are positioned away from the light-receiving region and other circuit components, eliminating the formation of high-frequency reflection points and resonance while maintaining electrical connection functionality.
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
This design enables a smaller submount and improved reception sensitivity by eliminating resonance and high-frequency reflections, enhancing the device's performance.
Implementation Method 1
A semiconductor light-receiving device can sense light only in a p-n junction region
Implementation Method 2
light incident from the backside of the substrate is reflected by electrode metal mirrors back to an absorption layer to be absorbed again
Data Source
AI summary
A substrate has a front surface and a back surface opposite from the front surface. An n-type layer, a multiplication layer, a p-type electric field control layer, a light absorption layer, and a window layer are layered in order on the front surface. A p-type region is provided in part of the window layer. An anode electrode is provided on the p-type region and connected to the p-type region. An anode pad and a cathode pad are provided on the back surface. First and second connecting holes penetrates the substrate. A third connecting hole penetrates from the window layer to the n-type layer. The cathode pad is electrically connected to the n-type layer via the first connecting hole. The anode pad is electrically connected to the anode electrode via the second and third connecting holes. A light-receiving region is provided on the back surface.