Various self-assembled monolayers such as carcinoembryonic antigen (CEA), beta actin, and bovine
serum albumin (BSA) were detected using an AlN-based film bulk acoustic resonator (FBAR). AlN thin
film was deposited by reactive RF magnetron sputtering, on a substrate of Mo (100 nm)/Ti (34 nm)/SiO2
(480 nm)/Si (300 mm)/Si3N4 (300 nm). The film showed a strongly c-axis preferred orientation with a
main (0 0 2) peak, as well as a good full width at half maximum (FWHM) of 2.508 in XRD and rocking
curve results. The AlN-based FBAR was confirmed to have a resonant frequency of 2.477 GHz and a
sensitivity of 3514 Hz cm2/ng. In beta actin, BSA, and CEA, the frequency properties showed variation
values of 472.142, 932.573, and 685.421 kHz and mass sensitivities of 3530, 3506, and 3514 Hz-cm2/ng,
respectively. The FBAR sensor was confirmed to be very useful for detecting target antigens through the
binding of an antigen and an anti-body.
