Research On Integration Of SOI Pressure And Magnetic Field Multi - Function Sensor

In this paper, according to piezoresistive effect and operating principle of magnetic sensitive diode, the structure model of pressure and magnetic field multifunctional sensor was built by MEMS technology on SOI substrates(n-type Si <100> crystal orientation with high resistivity as device layer). The pressure sensitive structure was constructed by C-type Si cup and the Wheatstone bridge. The Wheatstone bridge was constituted by four diffused resistances on the square silicon membrane. The magnetic sensitive structure was Si magnetic sensitive diodes with long base region outside the square silicon membrane. Theoretical analysis gives that the applied pressure P caused elastic deformation of square silicon membrane and the output voltage of Wheatstone bridge changed. The measurement of applied pressure P was realized. Under the effect of applied magnetic field B, the injection carriers of Si magnetic sensitive diodes with long base region deflected and the current of magnetic sensitive diodes changed. The measurement of applied magnetic field B was realized. Based on the integrated structure of sensor, the simulation models of pressure sensitive structure and magnetic sensitive structure were performed by ANSYS software and ATLAS device simulation software, respectively. Further to analyse the pressure-sensitive and magnetic-sensitive behaviors of multifunctional sensor. On the basis of this, analyzing the influence of silicon membrane shape, thickness and other facters on the pressure sensing characteristics of multifunctional sensor. Discussing the influence of base length of magnetic sensitive diodes on magnetic sensing characteristics. Then optimization designs of chip layouts ware realized by adopting L-Edit software.In this paper, the integrated chips of pressure and magnetic field multifunctional sensor were fabricated by MEMS technology. And the chip packaging of sensor was realized by wire bonding technology. At room temperature, the characteristic of the multifunctional sensor were researched by American Mensor CPC6000 pressure transmitterr test system, CH-Hall magnetic field generation system, OBIS GDJS-100LG-G high and low temperature humid test chamber. The experimental results show that when applied magnetic field B=0 T, the sensitivity of pressure sensitive structure is 1.376 mV/kPa. When applied magnetic field B≠0 T, the output-input characteristic curves of pressure sensitive structure was almost unchanged. It shows that applied magnetic field made weakly influence on pressure sensing characteristics of multifunctional sensor. When applied pressure P=0 kPa, I-V characteristic curves of Si magnetic sensitive diodes changed with applied magnetic field to realise the measurement of applied magnetic field. When applied pressure P≠0 kPa, I-V characteristic curves of Si magnetic sensitive diodes was almost unchanged. It shows that applied pressure made weakly influence on magnetic sensing characteristics of multifunctional sensor. The results of research show that the integrated chip can accomplish the measurement to applied pressure and applied magnetic field. The multifuctionalization and integration of sensors were realised.