Research And Design Of Spin-Valve Micro-Sensor

The discovery of giant magneto resistive effect opens up a new chapter for magnetic electronics discipline. Especially, GMR effect has a tremendous impact on the magnetic sensor research. Due to its fast response, high sensitivity, low saturation field and so on, the spin-valve structures materials are widely applied in the scientific research and industrial field. Since the research on the GMR effect theory just starts, according to the basic theory of GMR effect, the exploratory research on the design and fabrication for spin-valve micro-sensor is carried out based on MEMS technique.The basic principles, the application and the development of giant magneto resistance effect in the micro-sensor field are introduced in the thesis. The basic theory of spin-valve structure GMR materials is described. The characteristics of the spin-valve micro-sensor based on wheastone bridge structure are in detail investigated. The bridge structure will not only improve the sensor sensitivity and enhance temperature stability, but also can effectively reduce the impact of coercive force. The magnetron sputtering processes for magnetic thin films is researched. Especially, the magnetizing directions are investigated during the sputtering process. The two-steps deposition method is applied to prepare the spin valve multilayer film. Then, based on the selected spin valve film material, the process flow of the micro-sensor is designed. The layout for the spin valve structure micro-sensor is designed. Finally, the application circuits of the spin valve sensor chip are designed with AVR single chip microcomputer and manufactured. The manufactured sensors are measured in the magnetic environment. Since the experimental environment and actual conditions are considered, the characteristics, including temperature, sensor noise and hysteresis are ignored. The measured results show the resistance of the spin valve sensor chip mainly changes with magnetic field direction change within a certain range of magnetic field, the resistance little changes with the distance between the circuit and the magnet.