Silicon MEMS Resonant Light Sensor for Broad Wavelength Detection
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Solution Overview
Problem
Conventional bolometer-type light sensors face challenges in achieving high sensitivity, high speed, and room temperature operation due to issues with GaAs substrates, including insensitive bands in the terahertz to infrared regions, complex and expensive manufacturing processes, and low thermal conductivity, which affect response speed and scalability.
Innovation Solution
A light sensor utilizing a MEMS structure with a doubly-clamped beam made of high-resistivity silicon-on-insulator (SOI) material, incorporating a vibration actuator and detector to detect changes in resonant frequency based on thermal expansion, allowing for broad wavelength detection from visible light to terahertz waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a GaAs substrate is used in a bolometer-type light sensor, then the sensor can operate at room temperature with high sensitivity, but an insensitive band occurs in the terahertz to infrared regions due to phonon interaction in the GaAs crystal
Solution Approach 1:
The patent changes the material parameter from GaAs to silicon-based materials (Si, SiO2, Si3N4), which fundamentally alters the optical properties and eliminates the phonon interaction that causes the insensitive band in the terahertz to infrared region, while maintaining room temperature operation and high sensitivity
Solution Approach 2:
The patent employs a composite structure using multiple silicon-based materials (Si, SiO2, Si3N4) in different layers to achieve both structural support and optical transparency across broad wavelength ranges, eliminating the material limitation of single-material GaAs substrates
2Measurement precision
If a GaAs substrate is used in a bolometer-type light sensor, then the sensor can achieve high sensitivity, but the manufacturing process becomes complex and expensive
Solution Approach 1:
The patent changes the material system from GaAs to silicon-based materials, which are compatible with standard CMOS fabrication processes. This parameter change simplifies manufacturing by eliminating the need for complex GaAs-specific processing while maintaining high detection sensitivity through the preserved MEMS structure and thermal expansion mechanism
Solution Approach 2:
The patent adopts inexpensive silicon-based materials that can be mass-produced using established semiconductor manufacturing techniques, replacing expensive GaAs substrates. This approach enables cost-effective production of high-performance light sensors suitable for widespread application
3Temperature
If a GaAs substrate is used in a bolometer-type light sensor, then the sensor can operate at room temperature, but the thermal conductivity is low which affects response speed
Solution Approach 1:
The patent changes the material thermal conductivity parameter by using silicon-based materials with higher thermal conductivity compared to GaAs. This parameter change enables faster heat transfer from the light absorber to the resonator, improving response speed while maintaining room temperature operation through the same thermal expansion detection mechanism
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 sensor achieves high sensitivity and fast response times across a broad wavelength band, enabling high-speed, low-cost production and application in spectroscopic systems without insensitive bands, outperforming conventional GaAs-based sensors in sensitivity and speed.
Implementation Method 1
detect a change in resonant frequency with high sensitivity due to thermal expansion caused by a temperature change in the beam on the basis of the incidence of light
Implementation Method 2
a vibration actuator configured to generate vibration on the basis of an input signal
Implementation Method 3
a resonator having a doubly-clamped beam formed in a MEMS structure using a silicon material, configured to vibrate on the basis of the vibration transmitted by the vibration actuator and having a resonant frequency that changes in response to input of light
Data Source
AI summary
A light sensor includes a vibration actuator configured to generate vibration on the basis of an input signal, a resonator having a doubly-clamped beam formed in a MEMS structure using a silicon material, configured to vibrate on the basis of the vibration transmitted by the vibration actuator and having a resonant frequency that changes in response to input of light, and a vibration detector configured to detect vibration of the doubly-clamped beam.