Mg2Si Photodiode Array Bonding for Thermal Expansion Mismatch
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Solution Overview
Problem
The reliability of connecting Mg2Si photodiode arrays with ROIC structures is compromised due to the significant difference in thermal expansion coefficients, leading to position shifts and potential failures in the connecting portions.
Innovation Solution
A photodiode array design incorporating a PIN semiconductor layer with Mg2Si, a support member made of a light-transmissive material with a lower thermal expansion coefficient than Mg2Si, and a connection layer that allows light transmission, along with a manufacturing method that includes forming a through groove and bonding the support member to the connection layer, effectively reducing thermal expansion-induced position shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a support member is added to reduce thermal expansion, then reliability of connecting portion is improved, but device complexity increases
Solution Approach 1:
A support member is introduced as an intermediary component between the Mg2Si photodiode array and the ROIC structure. This support member has a lower coefficient of thermal expansion than Mg2Si, acting as a mediator to reduce the thermal expansion difference and prevent position shifts in the connecting portion during temperature changes.
Solution Approach 2:
The coefficient of thermal expansion parameter is changed by selecting a support member material with a lower coefficient than Mg2Si. This parameter change in the support member creates a gradient that reduces the overall thermal expansion mismatch between the photodiode array and the ROIC structure, thereby improving connection reliability.
2Illumination intensity
If connection layer is made light-transmissive to maintain light transmission, then light transmission is maintained, but manufacturing precision requirements increase
Solution Approach 1:
The connection layer is designed with local quality variations: it is light-transmissive in the optical path region to allow light transmission to the photodiode, while providing structural support and electrical connection properties in other regions. This localized differentiation maintains light transmission without compromising the structural integrity required for precise manufacturing.
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 enhances the reliability of the connecting portion between the Mg2Si photodiode array and the ROIC structure by suppressing thermal expansion, improving the stability and efficiency of the photodiode array while maintaining light transmission and reducing position shifts.
Implementation Method 1
the support member is made of a light-transmissive member having a lower coefficient of thermal expansion than Mg2Si included in the PIN semiconductor layer
Implementation Method 2
the connection layer includes an opening portion through which light is transmitted to the PIN semiconductor layer via the support member
Implementation Method 3
A photodiode is known as an element that converts light into an electrical signal
Data Source
AI summary
A PIN semiconductor layer including Mg2Si, a first electrode connected to a first surface of the PIN semiconductor layer, a support member being in contact with a surface of the first electrode via a connection layer, a second electrode and a third electrode which are connected to the PIN semiconductor layer on a second surface opposite to the first surface of the PIN semiconductor layer, and an ROIC structure connected to the second electrode and the third electrode are provided. The first electrode is disposed around a through groove, the second electrode is connected to a portion of the second surface where a p+ type semiconductor layer is located, the third electrode is connected to the first electrode and the through groove, the support member comprises a light-transmissive member having a lower coefficient of thermal expansion than Mg2Si, and the connection layer includes an opening portion.