Design And Fabrication Of Silicon Resonant Pressure Sensor

Recently, the resonant pressure sensor is developed with the advantages such as highsensitivity, stable performance, small size, low power consumption and so on. The signal output canbe connected directly to the digital interface, to overcome poor anti-interference ability of thetraditional piezoresistive pressure sensor.Firstly, based on the theory of traditional resonant pressure sensor, two different resonant beamstructure resonant pressure sensors are proposed, including SiO2-Si3N4-SiO2composite resonantbeam structure and Si3N4diagonal resonant beam structure. The electrothermal excitation andpiezoresistive pick-up resistance method is adopted. The excitation resistors and pick up vibrationresistors in the composite beam structure are polysilicon resistors, and the excitation resistors andpick up vibration resistors in the diagonal beam structure are platinum resistors. Based on themechanics and vibration theory fixed beam, of the resonant pressure sensor model is in-depthanalyzed. The simulation model of the resonant pressure sensor is established with ANSYSsoftware. The electric thermal response, modal and harmonic analysis are carried out to determinethe optimal structure and size of the chip. The finite element analysis results show that thesensitivity of the resonant pressure sensor with SiO2-Si3N4-SiO2composite beam structure is63.5Hz/KPa, and the sensitivity of the sensor with Si3N4diagonal beam structure is16.24Hz/KPa.Based on MEMS process technology, the production process for the SiO2-Si3N4-SiO2compositebeam structure and Si3N4diagonal beam structure is designed. The polysilicon sacrificial layertechnology can get the composite beam structure better, and the process of beam structure is simple.Finally, the packaging structure and the test circuit for the resonant pressure sensor are brieflyintroduced.