Simulation design of piezoresistive sensors based on COMSOL

With the rapid development of silicon manufacturing technology, silicon uses as a substrate material diffusion type pressure sensor have many advantages, such as small package size, light weight, fast response, simple structure. Besides, resistive pressure sensors have a good linearity. In this paper, we proposed a novel piezoresistive pressure sensor structure. The proposed structure consists of four-terminal resistances. A square film is embedded in four-terminal resistances. When the film is distorted, it will lead to four-terminal resistance induced difference pressure by difference potential. According to differential voltage of piezoresistive resistor, the pressure size can be calculated. Our simulation results show that the diaphragm have 1.2 μm of displacement under pressure of 100 kPa. According to the simple isotropic model given in the reference, the 4 μm magnitude is predicted. Our simulation results are reasonable, and the local stress is the same as the value of the prediction equation. Considering the size of equipment and doping concentration, the model shows a good agreement with the predicted results during operation. The proposed piezoresistive sensor structure has many advantages over traditional piezoresistive sensor, such as higher sensitivity, better linearity, and anti-interference ability. The piezoresistive sensor can be widely applied in hydraulic systems, safety control System, injection mold, monitoring mine pressure and compressor.