Research On Fabrication And Characteristics Of Silicon Magnetic Resistor Transistor Based On MEMS Technology

In this paper,the integrated silicon magnetic sensitivity transistor differential structure is given based on the analysis of the basic structure, working principle and characteristics for silicon magnetic sensitivity transistor with three-dimensional structure, and the integrated structure is comprised of two silicon magnetic sensitivity transistors(T-1 and T-2) with opposite magnetic sensitivity directions and collector load resistors, that owns a common emitter(E), two bases(B1, B2), two collectors(C1, C2), and two collector load resistors(RL1, RL2). Given by theoretical analysis, this structure can realize measurement of magnetic field and the sensitivity can be improved. The simulation models of silicon magnetic sensitivity transistor differential structure were established by ATLAS software based on the basic structure. Both the base region length and base region width were studied to know the influence of the magnetic characteristics of silicon magnetic sensitivity transistor differential structure so that the structure’s geometric parameters are optimized. Based on the above, the integrated chips of silicon magnetic sensitivity transistor differential structure were fabricated on the P-type <100> double-side polished high resistivity silicon wafer by micro electromechanical system(MEMS) technology.At room temperature, the IC-VCE characteristic, magnitic characteristic and temperature characteristic of silicon magnetic transistor and integrated chip differental structure composed by silicon magnetic transistors were tested by semiconductor characteristic analysis system(KEITHLEY 4200), magnetic field generator system(CH-1) and high/low temperature test chamber(OBIS GDJS-100LG-G). The collector voltage absolute magnetic sensitivity for silicon magnetic transistor and integrated chip differental structure are 259 m V/T and 443 m V/T, and the the collector output voltage relative temperature coefficients are 116 ppm/°C and 54.4 ppm/°C respectively, where VDD=10.0 V, IB=8.0 m A and the base region length L is 150 μm. The experiment results show that the integrated differential structure can improve magnetic sensitivity and modify the temperature characteristic for silicon magnetic transistor. Base on the above, the influence of base region length for integrated chip’s IC-VCE characteristic and magnitic characteristic were studied, the collector voltage absolute magnetic sensitivities of integrated silicon magnetic sensitivity transistor differential structure with the base lengthes of 120 μm, 150 μm and 180 μm are 435 m V/T, 390 m V/T and 390 m V/T, where VDD=6.0 V, IB=8.0 m A. So when the length of base is 120 μm, the integrated chip has optimal magnetic characteristics.