Technology Research Of Micromachined Resonant Pressure Sensors

Microstructure resonant pressure sensor works by mechanical resonator when its resonat frequency changes with pressure. It was characterized by small size, high precision, stable and easy to interface with digital circuit and has broad application prospects. Static electricity, optical thermal and electromagnetic are several common incentive forms, the methods of picking up signal usually include capacitance detection, piezoresistive pick-up, electromagnetic induction and piezoelectric pick-up.In this paper, the resonant pressure sensor is using electric excitation and piezoresistive pick-up. The study includes the resonant theory, design, computer simulation, manufacture and testing in microstructure resonant pressure sensor. The main technical difficulties are sensitive chip production and testing.Analytical method and the finite element method are used to analyze the resonant theories and characteristics of the pressure-sensitive features. To improve sensitivity, we put forward a new type of silicon island structure. Finite element analysis software is used to simulate the new silicon beam structures. The analysis result shows that the sensitivity of island-resonant beam sensor can be increased by four times over. MEMS technology is used to manufacture the sensor, then a package structure with reduced stress is developed to complete pressure sensor package. The principle PLL weak signal detection technology is used to study and design the open-loop frequency test system and the closed-loop self-testing system.