Fabrication of a film bulk acoustic wave resonator from nano-crystalline diamond

A proposed new type of diamond-based frequency device has been fabricated for the first time through the use of nano-crystalline diamond as the thin film component of a Film Bulk Acoustic Resonator (FBAR) device. The new fabrication process uses Si MEMS-based fabrication techniques on 200 nm thick nano-crystalline diamond deposited on a 4 inch silicon wafer. After completely removing the silicon substrate below the device by the BOSCH process, one port resonators with a diaphragm structure have been fabricated. All the devices produced in the first fabrication run operated successfully with a high frequency response of 3.5 GHz.