Silicon Bulk Micromachined High Q Film Bulk Acoustic Resonator Devices with Mo/AlN/Mo Structures

ABSTRACT

Fully integrated film bulk acoustic resonators and band pass filters using a bulk micromachining method have been designed, fabricated, and characterized. Aluminum nitride (AlN) has been used for a piezoelectric material and Molybdenum (Mo) was employed as top and bottom electrodes. Also, Ti seed layers were used in order to obtain highly c-axis oriented AlN piezoelectric films. The film bulk acoustic resonators fabricated with highly c-axis oriented AlN films showed good performances such as an effective mechanical coupling coefficient of 7.5% and a quality factor of 1530. The band pass filter consisted of seven film bulk acoustic resonators with a high quality factor exhibited a transmission loss of −3.2 dB, a ripple of 1.2 dB in pass band, and attenuation values of −38 dB and −49 dB at both band boundaries, respectively.

Keywords:

• Piezoelectricity
• FBAR
• resonators
• band pass filters
• acoustic waves
• RF MEMS
• AlN
• Molybdenum

Acknowledgments

This research was supported by the Ministry of Science and Technology under 21st Frontier Intelligent Microsystem Program.