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Analysis of Structural Design Variations in MEMS Capacitive Microphones
Tzu-Huan Peng1, Huei-Ju Hsu2, Jin H Huang3
1Ph.D. Program of Mechanical and Aeronautical Engineering, Feng Chia University, Taichung 407102, Taiwan.
Sensors (Basel, Switzerland)
|February 13, 2025
Summary
Microstructure design in micro-electro-mechanical systems (MEMS) microphones impacts acoustic performance. Rib-reinforced backplates enhance MEMS microphone reliability, while suspended diaphragms improve signal-to-noise ratio (SNR).
Area of Science:
- Acoustic Engineering
- Micro-electro-mechanical Systems (MEMS)
Background:
- Microstructure design critically influences the acoustic performance of MEMS capacitive microphones.
- Key performance metrics are significantly affected by variations in microstructural elements.
Purpose of the Study:
- To investigate the impact of different microstructures on MEMS microphone acoustic performance.
- To analyze the effects of rib-reinforced backplates, suspended diaphragms, and outer vent holes on microphone specifications.
Main Methods:
- Implemented three MEMS microphone designs incorporating various microstructures.
- Constructed equivalent circuit models for simulating sensitivity, signal-to-noise ratio (SNR), and low corner frequency (LCF).
- Utilized Finite Element Analysis (FEA) for acoustic damping, diaphragm parameters, and pre-deformation; conducted Compressed Air Test (CAT) for mechanical reliability.
Main Results:
- Rib-reinforced backplates were found to significantly improve microphone reliability, increasing Compressed Air Test (CAT) pass rates.
- Suspended diaphragms demonstrated higher mechanical compliance, leading to enhanced SNR but reduced acoustic overload point (AOP).
- Outer vent holes showed potential for diaphragm vent hole functionality, though their effect on AOP requires further investigation.
Conclusions:
- Microstructure engineering is vital for optimizing MEMS microphone performance and reliability.
- Specific microstructures like rib-reinforced backplates and suspended diaphragms offer distinct advantages for MEMS microphone design.
- Further research is needed to fully characterize the impact of outer vent holes on acoustic overload point (AOP).
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