Development of 0-level Packaged Dual SAW Pressure and Temperature Sensors on GaN Thin Membranes

The paper presents the design, manufacturing and characterization of 0level packaged dual SAW pressure and temperature sensors developed on GaN/Si/Mo thin membranes. Molybdenum film was deposited on the backside of membrane, to support a higher pressure. FEM simulations were performed in order to predict the mechanical behavior of the membrane. The dual sensor, consisting of single SAW resonator, was fabricated by nanolithography, while the membrane under the resonator was made by dry etching of the Silicon substrate. Dual sensors parameters (sensitivity, pressure coefficient of frequency PCF and temperature coefficient of frequency -TCF have been measured before and after packaging. The pressure sensitivity and PCF show high values before encapsulation (1102 kHz/Bar and 126 ppm/Bar) and an insignificant dropping of the values after encapsulation.