Study, design, microfabrication and characterization of a new CMOS compatible multi-terminal pressure sensor with enhanced sensitivity

This paper presents the design, microfabrication and characterization of a CMOS compatible multi-terminal pressure sensor (MTPS). The design is supported by an analytical as well by a numerical study. This sensor is an alternative to the pressure sensors based on both: the conventional silicon Wheatstone Piezoresistive Bridge (WB) and Four-Terminal Pressure Sensors (FTPS). The layout of the MTPS is designed in such a way that the sensor sensitivity is effectively improved and the short-circuit effects, which are modeled by the geometrical correction factor (G), can be minimized. The effect of a polysilicon gate over the active region of the sensor is studied in order to further enhance its sensitivity. The MTPS was fabricated using two different foundries: one academic (CCS-UNICAMP) and another commercial (0.35 μm CMOS AMS). The MTPS sensor sensitivity amounts to 4.8 and 0.24 mV/psi, respectively. The influence of temperature on the sensors transfer function is also studied.