Sub-micron gap a-Si:H thin film Lamé-mode resonator processed at low temperature on a glass substrate

A laterally vibrating square plate fabricated using low temperature (<;250°C) surface micromachining technology and hydrogenated amorphous silicon (a-Si:H) thin films as a structural layer with submicron capacitive actuation gaps has been demonstrated in this work. The resonator is fabricated on a glass substrate by hard mask and deep reactive ion etching processes resulting in transduction gaps of 400 nm. Operating in the Lamé-mode, the resonator vibrates at a frequency of 13.63 MHz with a quality factor as high as 6000 in air. This result represents an important step towards the development of fully miniaturized and monolithically integrated a-Si:H-based MEMS. Using the resonators presented in this work, large-area (on glass and polymer substrates) and CMOS compatible, monolithically integratable thin-film silicon MEMS applications can be envisaged.