Archives of Acoustics, 40, 4, pp. 527–537, 2015
10.1515/aoa-2015-0052

Electroacoustic Analysis of a Controlled Damping Planar CMOS-MEMS Electrodynamic Microphone

Fares TOUNSI
ENI Sfax
Tunisia

Brahim MEZGHANI
ENI Sfax
Tunisia

Libor RUFER
TIMA
France

Mohamed MASMOUDI
ENI Sfax
Tunisia

This paper gives a detailed electroacoustic study of a new generation of monolithic CMOS micromachined electrodynamic microphone, made with standard CMOS technology. The monolithic integration of the mechanical sensor with the electronics using a standard CMOS process is respected in the design, which presents the advantage of being inexpensive while having satisfactory performance. The MEMS microphone structure consists mainly of two planar inductors which occupy separate regions on substrate. One inductor is fixed; the other can exercise out-off plane movement. Firstly, we detail the process flow, which is used to fabricate our monolithic microphone. Subsequently, using the analogy between the three different physical domains, a detailed electro-mechanical-acoustic analogical analysis has been performed in order to model both frequency response and sensitivity of the microphone. Finally, we show that the theoretical microphone sensitivity is maximal for a constant vertical position of the diaphragm relative to the substrate, which means the distance between the outer and the inner inductor. The pressure sensitivity, which is found to be of the order of a few tens of μV/Pa, is flat within a bandwidth from 50 Hz to 5 kHz.
Keywords: MEMS sensor; acoustical model; monolithic electroacoustic microphone; suspended diaphragm; lumped element modeling.
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References

Abuelma’atti M.T. (2007), Large signal performance of micromachined silicon inductive microphones, Journal of Applied Acoustics, 68, 10, 1286–1296.

Baltes H., Brand O., Fedder G.K., Hierold Ch., Korvink J.G., Tabata O. (2005), CMOS-MEMS: Advanced Micro and Nanosystems, 1st edition, Wiley-VCH.

Bao M.H. (2000), Micro mechanical transducers: pressure sensors, accelerometers and gyroscopes, Handbook of Sensors and Actuators, Elsevier, Amsterdam.

Bao M. (2005), Analysis and Design Principles of MEMS Devices, 1st edition, Elsevier.

Beranek L.L. (1954), Acoustics, McGraw-Hill Inc, New York, USA.

Blackstock D.T. (2000), Fundamentals of Physical Acoustics, Wiley, Hoboken, USA.

Chen Jen-Yi, Hsu Yu-Chun, Lee Shu-Sheng, Mukherjee Tamal, Fedder Gary K. (2008), Modeling and simulation of a condenser microphone, Sensors and Actuators A, 145–146, 224–230.

Gong S.C. (2004), Effects of pressure sensor dimensions on process window of membrane thickness, Sensor and Actuators A, 112, 286–290.

Horng Ray-Hua, Chen Kuo-Feng, Tsai Yao-Cheng, Suen Cheng-You, Chang Chao-Chih (2010), Fabrication of a dual-planar-coil dynamic microphone by MEMS techniques, Journal of Micromechanics and Microengineering, 20, 1–7.

Horowitz S., Nishida T., Cattafesta L. (2007), Development of a micromachined piezoelectric microphone for aeroacoustics applications, Journal of Acoustical Society of America, 122, 3428–3436.

Howard C.Q., Cazzolato B.S. (2014), Acoustic Analyses Using Matlabr and Ansysr, CRC Press.

Kovacs G.T.A., Maluf N.I., Petersen K.E. (1998), Bulk micromachining of silicon, Proc. IEEE, 86, 1536–1551.

Kronast W., Muller B., Siedel W., Stoffel A. (2001), Single chip condenser microphone using porous silicon as sacrificial layer for the air gap, Sensors and Actuators A, 87, 188–193.

Kühnel W., Hess G. (1992), Micromachined sub-miniature condenser microphones in silicon, Sensors and Actuators A, 32, 560–564.

Ma Ji (2015), Advanced MEMS-based technologies and displays, Displays Journal, 37, 2–10.

Merhaut J. (1981), Theory of Electroacoustics, McGraw-Hill Inc, USA.

Mir S., Charlot B., Rufer L., Parrain F., Martinez S. (2002), Conception de microsystèmes sur silicium, Traité EGEM, série Electronique et micro-électroniques, Hermes sciences – Lavoisier.

Morse P.M., Ingard K.U. (1968), Theoretical Acoustics, Chapter 7, 383–394, McGraw-Hill.

Olson H.F. (1976), Acoustical Engineering, Van Nostrand, Princeton, USA.

Rossi M. (2007), Audio, Presses polytechniques et universitaires Romande, Italy.

Royer M., Holmen J.O., Wurm M.A., Aadland O.S., Glenn M. (1983), ZnO on Si integrated acoustic sensor, Sensor and Actuators, 4, 357–362.

Sheplak M., Breuer K.S., Schmidt (1998), A wafer-bonded, silicon-nitride membrane microphone with dielectrically-isolated single-crystal silicon piezoresistors, Technical Digest Solid-State Sensor and Actuator Workshop, Transducer Res, Cleveland, USA, 23–26.

Tounsi F., Rufer L., Mezghani B., Masmoudi M., Mir S. (2009a), Electromagnetic Modeling of an Integrated Micromachined Inductive Microphone, Proceedings of the 4th IEEE International Conference on Design & Test of Integrated Systems in Nanoscale Technology, pp. 1–5, Egypt.

Tounsi F., Rufer L., Mezghani B., Masmoudi M., Mir S. (2009b), Highly Flexible Membrane Systems for Micromachined Microphones – Modeling and Simulation, Proceedings of the 3rd Int. Conf. on Signals, Circuits and Systems, pp. 1–6, Tunisia.

Tounsi F. (2013), Theoretical Electromagnetic survey: Application to a planar CMOS-MEMS electrodynamics microphone, [in:] Novel Advances in Microsystems Technologies and Their Applications, pp. 205–246, CRC Press, Taylor & Francis.




DOI: 10.1515/aoa-2015-0052

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