Fabrication of Surface Micromachined AlN Piezoelectric Microstructures and its Potential Apllication to RF Resonators

Saravanan, S. and Berenschot, E. and Krijnen, G. and Elwenspoek, M. (2005) Fabrication of Surface Micromachined AlN Piezoelectric Microstructures and its Potential Apllication to RF Resonators. In: Symposium on Design, Test, Integration, and Packaging of MEMS/MOEMS (DTIP), 1-3 June 2005, Montreux, Switzerland.

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Abstract:	We report on a novel microfabrication method to fabricate aluminum nitride (AlN) piezoelectric microstructures down to 2 microns size by a surface micromachining process. Highly c-axis oriented AlN thin films are deposited between thin Cr electrodes on polysilicon structural layers by rf reactive sputtering. The top Cr layer is used both as a mask to etch the AlN thin films and as an electrode to actuate the AlN piezoelectric layer. The AlN layer is patterned anisotropically by wet etching using a TMAH (25%) solution. This multilayer stack uses silicon-di-oxide as a sacrificial layer to make free-standing structures. One-port scattering paramenter measurement using a network analyzer show a resonant frequency of 1.781 GHz on a clamped-clamped beam suspended structure. The effective electromechanical coupling factor is calculated as 2.4 % and the measured bandwidth is 13.5 MHz for one such a doubly clamped beam (990x30) μm2.
Item Type:	Conference or Workshop Item
Faculty:	Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:	Transducers Science and Technology (TST)
Link to this item:	http://purl.utwente.nl/publications/52576
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