Design Of Spring-Supported Diaphragm Capacitive MEMS Microphone

• Main Author: Mohamad, Norizan
• Format: Thesis
• Language: English
• Published: UTeM 2016
• Subjects: T Technology (General); TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utem.edu.my/id/eprint/18844/1/Design%20Of%20Spring-Supported%20Diaphragm%20Capacitive%20MEMS%20Microphone%2024%20Pages.pdf; http://eprints.utem.edu.my/id/eprint/18844/; http://library.utem.edu.my:8000/elmu/index.jsp?module=webopac-d&action=fullDisplayRetriever.jsp&szMaterialNo=0000101007
• Institution: Universiti Teknikal Malaysia Melaka

In this research project, the design and performance optimization techniques of a microelectromechanical (MEMS) condenser microphone will be studied and described using several established plate theories and numerical analysis. MEMS microphone is shown to have been increasingly popular to be used in various consumer electronic products especially in the mobile phone industry and hearing aid devices. Thus, it is important for the microphone designers to be able to design and improve a microphone’s performance given sets of design constraints in the shortest time possible while reducing the overall overhead cost associated with the mass production exercise. The proposed new spring-supported diaphragm MEMS microphone has a higher open-circuit sensitivity, sufficiently high pull-in voltage, adequate frequency response in the audio range bandwidth, and uses fewer fabrication masks to reduce the overall production cost and possibly reduce the production rejection rate. The mathematical modelling of the proposed spring diaphragm has been described in detail to relate its performances with several of its structural dimensions such as spring width and length, diaphragm area, air gap distance, and diameter of backplate holes. Coventor FEM software has been used to simulate the mechanical performances of the final structure and to verify the mathematical modelling derived for the proposed spring microphone. Numerical results from Matlab and Coventor FEM software show that the proposed spring diaphragm has about 100 times higher sensitivity compared with the edgeclamped diaphragm microphone of the same diaphragm area. Various numerical performance analysis graphs have been presented and used to obtain the optimizedmicrophone parameters by taking the points where the open-circuit sensitivity will be the highest, operating bandwidth of at least 20kHz, and the pull-in voltage threshold is at least 3 times its bias voltage.