Design, fabrication and reliability study of piezoelectric ZnO based structure for development of MEMS acoustic sensor
- 121 Downloads
This paper reports a piezoelectric zinc oxide (ZnO) based acoustic sensor for high sound pressure level (SPL) with wide bandwidth for audio and aeroacoustic applications. The proposed structure has been simulated using finite element method (FEM) based MEMS-CAD tool Coventorware and optimized the dimensions of the diaphragm for a large dynamic range of 100-180 dB sound pressure level (SPL) and large bandwidth (22 kHz). The resonant frequency of the simulated structure is 67 kHz. Optimized structure dimensions have been chosen and fabricated the structure. The diaphragm structure has been released using bulk micromachining wet etching process. The ZnO thin film of 1.71 µm has been deposited using radio frequency (RF) sputtering technique and characterized using X-ray powder diffraction (XRD) and atomic force microscopy (AFM). The resonant frequency of the fabricated device is measured using laser doppler vibrometer (LDV) and found to be 65 kHz. The experimental sensitivity of the fabricated device is measured and is found to be 80 μV/Pa. The reliability testing of the fabricated structure was performed. The maximum current that can be passed across aluminum (Al) and deposited ZnO edge was found to be 2.69 A without any damage. The electrical characterization such as capacitance, loss (tan \(\delta\)) of fabricated device parameters were measured and the effects of frequency variation on both were also studied.
The authors express their gratitude to the Director, CSIR-Central Electronics Engineering Research Institute, Pilani and MRC Centre, Malaviya National Institute of Technology, Jaipur, India for providing the facilities for this work. One of the authors, Dr. Mahanth Prasad, acknowledges the financial support received from Science and Engineering Research Board (SERB), India through scheme EMR/2017/005107. The author, Mr. Ashish Kumar acknowledges the support from Visvesvaraya Ph.D. Scheme for Electronics and IT/ITes of Ministry of Electronics & IT, Government of India (Grant no-1000110042).
- Assouar MB, Elmazria O, Elhakiki M, Alnot P (2004) Study of structural and microstructural properties of AlN films deposited on silicon and quartz substrates for surface acoustic wave devices. J Vac Sci Technol B Microelectron Nanometer Struct 22:1717. https://doi.org/10.1116/1.1767196 CrossRefGoogle Scholar
- Giovanni MD (1982) Flat and corrugated membrane design handbook. Mercel Dekker Inc, New YorkGoogle Scholar
- Ozdogan M, Towfighian S (2016) A MEMS microphone using repulsive force sensors. In: Volume 4: 21st design for manufacturing and the life cycle conference; 10th international conference on micro- and nanosystems. ASMEGoogle Scholar
- Reagan T, Meloy J, Underbrink JR, Sheplak M (2017) Fabrication and characterization of a flush-mount MEMS piezoelectric dynamic pressure sensor and associated package for aircraft fuselage arrays. In: 55th AIAA Aerosp Sci Meet, pp 1–9. https://doi.org/10.2514/6.2017-0477
- Said MH, Tounsi F, Mezghani B, Ahmed A, Pandit S, Patkar R, Dixit P, Baghin MS, Rao VR (2018) Induced stress enhancement using U-shaped arms in a 3-axis piezoresistive MEMS accelerometer. In: 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD). IEEE, Hammamet, Tunisia, pp 1481–1486. https://doi.org/10.1109/SSD.2018.8570360 CrossRefGoogle Scholar