US Patent 7176770 Capacitive vertical silicon bulk acoustic resonator

Disclosed are high frequency, vertical silicon bulk acoustic resonators. Resonator structures having a relatively large transduction areas fabricated using a HARPSS fabrication process provide for high frequency capacitive resonators with significantly low impedance values. Impedance values as low as a few kilo-Ohms to sub-kilo-Ohm and quality factors in the range of 20,000 to 90,000 in the VHF range have been achieved for a first thickness mode of fabricated vertical silicon bulk acoustic resonators. Resonant frequencies as high as 983 MHz have been demonstrated for higher third thickness modes of the vertical silicon bulk acoustic resonators.