Fabrication and Temperature Test of a Multi-Physics Coupling MEMS Sensor Chip

A multi-physics coupling MEMS sensor chip is put forward in this paper. The chip integrates Fabry-Pérot (F-P) cavity pressure sensing unit, AlN piezoelectric film and Pt thermistor. The fabrication begins with a silicon wafer and a BF33 glass wafer. Magnetron sputtering and lift-off process on silicon wafer are applied to realize multilayer films and patterning, AlN film and Pt film included. The lower electrode of piezoelectric module is exposed by ICP etching. Bottom reflectivity and thickness of F-P cavity are respectively controlled by deposited Al-SiO₂ film and prepared SU-8 photoresist on glass wafer. The temperature test is applied after 3 hours' annealing at 300°C. The wire bonding package and three-wire bridge test scheme is adopted. The temperature coefficient of resistance is 1844 ppm/°C. The sensitivity is 0.2822 Ω/°C. The linearity is 1.65%. The resistance at 0°C is 153.1 Ω.