Research On Integration Of Magnetic Field/pressure/acceleration Sensors Based On MEMS Technology

This paper presents a magnetic field / pressure / acceleration monolithic integrated sensor based on micro-electromechanical systems(MEMS) technology. This structure consists of magnetic field sensor, pressure sensor and triaxial acceleration sensor. Based on Hall effect, the applied magnetic field can be measured by Hall magnetic field sensor with two Hall output ports. Based on piezoresistive effect, the pressure sensor is made up of C-type silicon cup and square silicon membrane. The applied pressure can be measured by detecting the output voltage of Wheatstone bridge which is constituted by the four piezoresistors on the membrane. Acceleration sensor consists of two mass blocks, four L-shaped beams and double beams in the middle. Twelve piezoresistors on the root of beams constitute three Wheatstone bridges. The applied acceleration can be measured by detecting the output voltages of three Wheatstone bridges. On that basis, ATLAS and ANSYS were used to establish the simulation model of magnetic field sensor, pressure sensor and acceleration sensor, respectively, and simulation analysis were carried on. Through the optimization of structural parameters, the monolithic integrated sensor chip layouts were designed by L-Edit integrated circuit layout design software. The sensor chips were fabricated on n-type <100> crystal orientation high resistance silicon wafer based on MEMS technology. And the sensor chips were packaged by electrostatic bonding process and inner wire bonding technology.At room temperature, magnetic field generator, pressure calibration system and acceleration sensor calibration system were used to establish monolithic integrated sensor testing system to research sensor characteristics. The experiment results indicate that, when the power supply voltage is 5.0 V, the sensitivities of magnetic field sensors(MS1 and MS2) of the monolithic integrated sensor are 172.6m V/T and 171.1m V/T, respectively. The sensitivity of pressure sensor is 0.842 m V/k Pa, and the sensitivities of triaxial acceleration sensor are 0.60 m V/g(x axis), 0.73 m V/g(y axis) and 2.60 m V/g(z axis), respectively. The experimental results show that the monolithic integrated sensor can be used to measure three quantities(five parameters), magnetic field, pressure and triaxial acceleration simultaneously. There is weak cross interference among different physical quantities. And it lays an important foundation for the further research of integrated sensor.