Characterization of low-temperature Ultrananocrystalline™ Diamond RF MEMS resonators

For the first time working MEMS resonators have been produced using low-temperature deposited (550 degrees C) Ultrananocrystalline (TM) Diamond (UNCD (TM)) films. Using a lumped-element model to fit experimental data, UNCD materials properties such as a Young's modulus of 710 GPa and an acoustic velocity of 14,243 m/s have been deduced. This is the highest acoustic velocity measured to date for a diamond MEMS structural layer deposited at low temperatures. A 10 MHz resonator shows a DC-tunability of the resonance frequency of 15% between 15 and 25 V and the breakdown voltage behavior shows electrostatic breakdown rather than electro-mechanical pull-down for higher frequency devices. Good resonant frequency reproducibility is observed when cycling the resonators over bias voltages from 15 to 25 V and over RF power levels of -10 to 10 dBm.