Design and fabrication of an absolute pressure MEMS capacitance vacuum sensor based on silicon bonding technology

Due to the need of miniaturization and integration for pressure monitoring fields, micro-electromechanical system (MEMS) vacuum sensor has attracted increasing attentions. In this paper, a touch-mode MEMS capacitance vacuum sensor with a full range of (20-84000) Pa based on silicon bonding technology was designed in the absolute pressure type. The design principle of the MEMS capacitance vacuum sensor was demonstrated, and the pressure-sensing diaphragm deflection is analyzed by ANSYS. The MEMS capacitance vacuum sensor was fabricated by self-stopped etch technique based on boron-doped process. The structure morphology and chemical composition of the boron-doped pressure-sensitive diaphragm were characterized by atomic force microscope (AFM), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The capacitance-pressure (C-P) performance of touch-mode MEMS capacitance vacuum sensor was evaluated by the vacuum testing system. The testing results show that the C-P curve is characteristic of piecewise, and the touch stage is the main working stage of the MEMS capacitance vacuum sensor, in which the sensor has relatively high sensitivity with 60.76 fF/Pa.