Sensitivity analysis of packaging effect of silicon-based piezoresistive pressure sensor

The silicon-based pressure sensor is one of the major applications in the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in the industry, but its requirement in terms of sensing accuracy and stability is more rigorous than that of many advanced applications. The major factor affecting the sensing stability of the piezoresistive pressure sensor is its thermal and packing effects. For a packaged pressure sensor, silicone gel is usually used to protect the die surface, so the thermal and packaging effects caused by the silicone gel should be taken into consideration to obtain better sensing sensitivity and stability. For fast design and optimization purpose, a finite element method (FEM) is adopted for sensor performance evaluation, packaging-induced signal variation, and thermal/packaging effects will be examined in this research. Several experiments are also performed to validate the finite element model. After the simulation is validated, an optimization analysis is carried out under different packaged pressure sensor design parameters. The simulation results show that the different geometry of the protection gel will influence pressure sensitivity significantly; base on analysis results, this research will conclude a design guideline for pressure sensor packages with concave and convex type of protection gel.