Bolometer THz Detector Air Gap Reduction
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Solution Overview
Problem
Conventional bolometer-type THz wave detectors experience a reduction in manufacturing yield due to cracks in the temperature detecting portion, which occur as a result of thermal expansion coefficient differences between the sacrificial layer and other materials, especially when the air gap is increased during the manufacturing process.
Innovation Solution
A bolometer-type THz wave detector with a thermal isolation structure where the temperature detecting portion is supported by a dielectric film, reducing the air gap to less than 8 μm, forming an optical resonant structure that enhances THz wave absorption and minimizes crack occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air gap is increased to improve THz wave absorption efficiency, then the absorption efficiency is improved, but cracks occur in the temperature detecting portion due to thermal expansion coefficient differences, reducing manufacturing yield
Solution Approach 1:
The patent changes the physical parameter of the air gap from 8-14 μm to less than 8 μm, fundamentally altering the structural configuration to eliminate thermal expansion stress while preserving detection functionality
Solution Approach 2:
The dielectric film serves as an intermediary component between the temperature detecting portion and the substrate, providing both mechanical support and thermal isolation while enabling THz wave transmission
2Productivity
If the air gap is reduced to less than 8 μm to prevent cracks and improve manufacturing yield, then manufacturing yield is improved, but THz wave absorption efficiency may be compromised
Solution Approach 1:
The dielectric film acts as a mediator that enables the small air gap structure to function effectively by providing thermal isolation and mechanical support while maintaining THz wave transmission capability
Solution Approach 2:
The patent optimizes the dielectric film thickness parameter to achieve the right balance between mechanical support, thermal isolation, and THz wave transmission, enabling efficient absorption despite the reduced air gap
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 reduced air gap structure improves the manufacturing yield and absorption efficiency of THz waves, reducing the frequency of defective pixels and maintaining high sensitivity.
Implementation Method 1
when taking account of the absorbing structure using optical interference
Implementation Method 2
an optical resonant structure formed by the reflective film and the temperature detecting portion
Implementation Method 3
a bolometer-type THz wave detector having a thermal isolation structure
Implementation Method 4
a temperature detecting portion (diaphragm) 14 composed of the second protecting film 6, a bolometer thin film 7
Data Source
AI summary
The bolometer-type THz wave detector according to the present invention has a thermal isolation structure in which a temperature detecting portion including a bolometer thin film connected to electrical wirings is supported in a state of being raised from the substrate by a supporting portion including the electrical wirings connected to a Read-out integrated circuit formed in a substrate, and the detector comprises a reflective film formed on the substrate, an absorbing film formed on the front surface or back surface or at an inner position in the temperature detecting portion , whereby an optical resonant structure is formed by the reflective film and the absorbing film, and a dielectric film formed on the reflective film. The dielectric film thickness f is set so that air gap between an upper surface of the dielectric film and a lower surface of the temperature detecting portion is smaller than 8 μm.