Research On 3D Magnetic Sensor Model Construction And Integration

In this paper, a 3D magnetic sensor monolithic integrated structure model is build, based on Hall Effect and the working principle of the silicon magnetic sensitivity transistor. The integrated structure composes four cubic structure silicon magnetic sensitivity transistors and a Hall magnetic sensor includes four emitters, four bases, four collectors, two Hall voltage output electrodes and two control current electrodes. Theoretical analysis indicates that, four silicon magnetic sensitivity transistors placed along the magnetic sensitive directions of the x axis and the y axis constitute two differential structures in 2D plane, a Hall magnetic sensor is placed in the center of the chip to realize measurement of z axis magnetic field, so the spatial 3D magnetic field can be detected by this structure. According to the integrated structure model of a single chip,the simulation model of 3D magnetic sensor was built by ATLAS to study the effect of the structural parameters at the characteristics of magnetic sensor. The simulation results show that spatial 3D magnetic field can be measured by this structure and the design can be optimized. Based on the above, the layouts of the chips were designed by the L-Edit, the monolithic integrated 3D magnetic sensor chips were fabricated on the P-type <100> high resistivity silicon wafer by micro electromechanical system(MEMS) technology, and the chip size is 2.3×2.3 mm2, the chips were packed by integrated circuit wire bonding technology.At room temperature, the static characteristics of the encapsulated 3D magnetic sensors were performed by CH-Hall magnetic calibration system to study the characteristics of magnetic sensor in x axis, y axis and z axis. The x axis and y axis sensitivities of differential structure silicon magnetic sensitivity transistor are 231 mV/T and 223 mV/T respectively, where the working voltage is 6.0 V and the base injection currents are 8.0 mA; the z axis Hall sensitivity is 74 mV/T, where working voltage is 5.0 V. On the basis, the rotating magnetic characteristics of monolithic integrated 3D magnetic sensor were studied under the constant magnetic field along x axis、y axis and z axis. The results show that the magnetic sensitivities of monolithic integrated 3D magnetic sensor with four cubic structure silicon magnetic sensitivity transistors have a good consistency along x axis、y axis, and the sensitivities are high, the integrated chip can realize the measurement of spatial 3D magnetic field.