Bolometer Infrared Sensor Electrode Layout for Lower Thermal Noise
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Solution Overview
Problem
Bolometer infrared sensors face challenges in enhancing infrared-light receiving sensitivity due to limitations in thermal insulation and thermal noise, which affect the electrical resistance and overall sensitivity of the sensor.
Innovation Solution
The design incorporates a bolometer infrared sensor with a phononic crystal structure in the beams and a line-and-space electrode structure, which improves thermal insulation and reduces thermal noise by optimizing the cross-sectional area and length of the current path in the resistance change film, along with phase matching for increased infrared light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thermal insulation performance of the beams is increased to improve infrared-light receiving sensitivity, then the sensitivity is improved, but the thermal noise increases due to the electrical resistance of the resistance change film
Solution Approach 1:
The electrode structure is segmented into line-and-space patterns rather than continuous electrodes. This segmentation reduces the total electrical resistance of the resistance change film by creating multiple parallel current paths, thereby reducing thermal noise while maintaining thermal insulation performance for improved infrared sensitivity.
Solution Approach 2:
The patent applies different structures to different parts of the electrode system. The line-and-space electrode structure is used specifically in regions where current flow is needed, optimizing local electrical properties while maintaining overall thermal insulation. This local optimization reduces thermal noise without compromising the thermal isolation required for sensitivity.
2Object-generated harmful factors
If the cross-sectional area of the current path in the resistance change film is increased to reduce electrical resistance, then the thermal noise is reduced, but the thermal insulation performance may be compromised
Solution Approach 1:
The patent transitions from a planar electrode design to a three-dimensional line-and-space structure. This dimensional change allows the current paths to be distributed throughout the volume of the resistance change film, effectively increasing the cross-sectional area for current flow without increasing the overall footprint, thereby maintaining thermal insulation performance while reducing electrical resistance and thermal noise.
3Object-generated harmful factors
If the path length of the current path in the resistance change film is decreased to reduce electrical resistance, then the thermal noise is reduced, but the electrode structure complexity increases
Solution Approach 1:
The continuous electrode is segmented into multiple line segments arranged in a periodic space pattern. This segmentation creates multiple short current paths in parallel, effectively reducing the overall path length for current flow through the resistance change film. The segmented structure reduces thermal noise while the periodic arrangement maintains manufacturing simplicity.
Solution Approach 2:
Multiple short current paths are merged into a single functional electrode system. The line-and-space segments work together as an integrated electrode structure, achieving the effect of reduced total resistance through parallel paths without requiring complex individual path designs. This merging approach simplifies the overall structure while achieving the goal of reduced thermal noise.
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 enhances the infrared-light receiving sensitivity by reducing thermal noise and improving thermal insulation, leading to higher sensitivity and effective detection of infrared light.
Implementation Method 1
PTL 1 discloses a technique of using a phononic crystal structure to increase the thermal insulation performance of the beams
Implementation Method 2
This structure aims at thermally insulating the infrared receiver from the base substrate
Implementation Method 3
The infrared receiver of a bolometer sensor includes a resistance change material the electrical resistance of which changes with temperature
Implementation Method 4
The infrared sensor disclosed in PTL 1 includes a bolometer sensor
Implementation Method 5
phase matching for increased infrared light absorption
Data Source
Figure 1A~1B
Figure 2~3B
Figure 3C~3E
AI summary
The present disclosure provides a technique for further increasing the sensitivity of an infrared sensor. The infrared sensor of the present disclosure includes a base substrate, an infrared receiver, a first beam, a second beam, first wiring, second wiring, and an infrared reflection film. Each of the first beam and the second beam has a connection portion connected to the base substrate and/or a member on the base substrate and a separated portion away from the base substrate, and is physically joined to the infrared receiver at the separated portion. The infrared receiver is supported by the first beam and the second beam to be away from the base substrate, and includes a lower electrode, an upper electrode, and a resistance change film. The resistance change film is sandwiched by the lower electrode and the upper electrode in a thickness direction, each of the lower and upper electrodes is electrically connected to the resistance change film, the lower and upper electrodes are electrically connected to the first wiring and the second wiring, respectively, at least one electrode selected from the lower electrode and the upper electrode has a line-and-space structure, and the infrared reflection film is provided at a position on a surface of the base substrate facing the infrared receiver.