Micromechanical bulk acoustic wave resonator

We describe the use of bulk acoustic mode in micromechanical silicon resonators operating at radio frequencies. Based on measured data from the fabricated resonator (f_r∼14 MHz, Q>100 000) we analyze the characteristic impedance and signal levels in such microdevices and compare the values with conventional quartz crystals. We find that the high impedance level of microresonators can be met with integration of the readout electronics and that silicon can accommodate significantly larger vibration energy densities than quartz. Based on the results, we anticipate a wide application range for the micromechanical bulk acoustic wave structures in future wireless communication devices and microsensors.