Dimension and doping concentration based noise and performance optimization of a piezoresistive MEMS pressure sensor

Micro electro mechanical system are highly miniaturized devices combining both electrical and mechanical components that are fabricated using integrated circuit batch processing techniques. P-type piezoresistors are diffused into the diaphragm in such a way that two of them are arranged parallel to the membrane edge and the other two are arranged perpendicular to the edge. The results reported in the literature evaluates the sensitivity by considering the change in the dimension of piezoresistors. But this work evaluates sensitivity and noise immunity of the piezoresistors by considering the change in the dimension of piezoresistors and the doping concentration when the sensor is being operated over a temperature ranging from 100 to 600 K. Various thermal effects are considered in the studies to evaluate the noise immunity. The simulation results clearly indicate that the dimension and doping concentration of piezoresistors play an important role in determining the sensitivity of the pressure sensor. It is found that the piezoresistor that senses the compressive plays an integral part in determining the sensor sensitivity. To have a better noise immunity, the doping concentration of the piezoresistor should be high if the sensor needs to operate at high temperatures else, the doping concentration should be low.