Mechanical performance of SiC based MEMS capacitive microphone for ultrasonic detection in harsh environment

S. A. Zawawi; A. A. Hamzah; F. Mohd-Yasin; B. Y. Majlis

doi:10.1117/12.2273717

31 August 2017 Mechanical performance of SiC based MEMS capacitive microphone for ultrasonic detection in harsh environment

S. A. Zawawi, A. A. Hamzah, F. Mohd-Yasin, B. Y. Majlis

Author Affiliations +

Proceedings Volume 10354, Nanoengineering: Fabrication, Properties, Optics, and Devices XIV; 103541J (2017) https://doi.org/10.1117/12.2273717
Event: SPIE Nanoscience + Engineering, 2017, San Diego, California, United States

Abstract

In this project, SiC based MEMS capacitive microphone was developed for detecting leaked gas in extremely harsh environment such as coal mines and petroleum processing plants via ultrasonic detection. The MEMS capacitive microphone consists of two parallel plates; top plate (movable diaphragm) and bottom (fixed) plate, which separated by an air gap. While, the vent holes were fabricated on the back plate to release trapped air and reduce damping. In order to withstand high temperature and pressure, a 1.0 μm thick SiC diaphragm was utilized as the top membrane. The developed SiC could withstand a temperature up to 1400°C. Moreover, the 3 μm air gap is invented between the top membrane and the bottom plate via wafer bonding. COMSOL Multiphysics simulation software was used for design optimization. Various diaphragms with sizes of 600 μm², 700 μm², 800 μm², 900 μm² and 1000 μm² are loaded with external pressure. From this analysis, it was observed that SiC microphone with diaphragm width of 1000 μm² produced optimal surface vibrations, with first-mode resonant frequency of approximately 36 kHz. The maximum deflection value at resonant frequency is less than the air gap thickness of 8 mu;m, thus eliminating the possibility of shortage between plates during operation. As summary, the designed SiC capacitive microphone has high potential and it is suitable to be applied in ultrasonic gas leaking detection in harsh environment.

Citation Download Citation

S. A. Zawawi, A. A. Hamzah, F. Mohd-Yasin, and B. Y. Majlis "Mechanical performance of SiC based MEMS capacitive microphone for ultrasonic detection in harsh environment", Proc. SPIE 10354, Nanoengineering: Fabrication, Properties, Optics, and Devices XIV, 103541J (31 August 2017); https://doi.org/10.1117/12.2273717

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