Bolometer THz Detector Optical Resonance Gap
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Solution Overview
Problem
Existing THz-wave detectors face challenges in achieving high performance and high yield due to difficulties in accurately controlling gaps between components, leading to low sensitivity and yield issues, especially when incorporating small detecting elements in a two-dimensional array.
Innovation Solution
A bolometer-type THz-wave detector is designed with a substrate, read-out integrated circuit, temperature detecting portion, absorbing film, and reflective film forming an optical resonance structure, where the gap between the reflective film and temperature detecting portion is set based on the infrared wavelength, and the sheet resistance of the temperature detecting portion is optimized for enhanced THz-wave absorptance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the detecting element is made small to enable two-dimensional array incorporation, then the array density increases, but the yield deteriorates due to extreme difficulty in incorporating elements of several μm size
Solution Approach 1:
The patent changes the gap parameter from the conventional 0.1-1 μm range to a larger range of 1.5-2.5 μm, which dramatically improves manufacturability and yield while maintaining detector performance through optimized optical resonance conditions
2Use of energy by moving object
If the gap between the glass layer and detecting element is reduced to 0.1-1 μm for efficient energy transmission, then the energy transmission efficiency improves, but the manufacturing difficulty increases due to the inability to control such small gaps with MEMS technology
Solution Approach 1:
The patent changes the gap parameter from the conventional 0.1-1 μm range to a larger range of 1.5-2.5 μm, which dramatically improves manufacturability and yield while maintaining detector performance through optimized optical resonance conditions
Solution Approach 2:
The patent introduces a flexible supporting portion that can elastically deform, allowing the temperature detecting portion to be positioned at the optimal gap distance through elastic deformation rather than rigid precision positioning
3Loss of energy
If the gap between the reflective film and temperature detecting portion is set within 1.5 to 2.5 μm for optimal resonance, then the THz-wave absorptance improves to 10% or more, but the manufacturing complexity increases due to precise gap control requirements
Solution Approach 1:
The patent changes the gap parameter from the conventional 0.1-1 μm range to a larger range of 1.5-2.5 μm, which dramatically improves manufacturability and yield while maintaining detector performance through optimized optical resonance conditions
Solution Approach 2:
The patent introduces a sacrifice layer as an intermediary element that enables precise gap control during manufacturing. The sacrifice layer is formed with controlled thickness and is selectively removed to create the required gap between the reflective film and temperature detecting portion
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 configuration significantly improves THz-wave absorptance, enabling the manufacture of high-performance THz-wave detectors with high yield by setting the gap between the reflective film and temperature detecting portion within 1.5 to 2.5 μm and adjusting the sheet resistance to achieve absorptance of 10% or more.
Implementation Method 1
a reflective film formed on a face opposed to the temperature detecting portion of the substrate for reflecting the THz wave and forming an optical resonance structure with the temperature detecting portion
Implementation Method 2
an absorbing film for absorbing a THz wave and having a sheet resistance set on the basis of the THz wave
Data Source
AI summary
In a micro-bridge structure in which a temperature detecting portion 14 (diaphragm) including a bolometer thin film 7 is supported by a supporting portion 13 in a state floated from a circuit substrate 2, a reflective film 3 reflecting a THz wave is formed on the circuit substrate 2, an absorbing film 11 absorbing the THz wave is formed on the temperature detecting portion 14, and an optical resonance structure is formed by the reflective film 3 and the temperature detecting portion 14. And a gap between the reflective film 3 and the temperature detecting portion 14 is set approximately ¼ of a wavelength of an infrared ray on the basis of the wavelength of the infrared ray (in a range of approximately 1.5 to 2.5 μm, for example), and a sheet resistance of the temperature detecting portion 14 is set in a range in which an absorptance of the THz wave becomes a predetermined value or above on the basis of the THz wave (in a range of approximately 10 to 100 Ω/sq.). By this arrangement, the absorptance of the THz wave is drastically improved while using the structure and manufacturing technique of a bolometer-type infrared detector.