The Research Of Angle Sensor Based On Magnetic Multilayers Anisotropic Magnetoresistance

With the expeditious development of information epoch as well as the acceleration of science and technology,magnetic field sensor has facilitated human life better and enhances the productive force and efficiency,in addition vigorously pushes forward the development of modern life.Among many sensors,the angle sensor based on anisotropic magnetoresistance(AMR)is a necessary object of discussion in the research of magnetic sensors,because of its above average sensitivity,intensive integration and low expenditure.In pace with the improvement of sensor manufactured standard,commercial NiFe monolayer anisotropic magnetoresistance in sensor applications has been insatiable in demand of simultaneous optimization of high efficiency and miniaturization.While the saturation magnetic field based on NiCo monolayer sensor is too large to be well applied to angle sensor.In view of above consideration,this paper put forward to make fully utilized of the superiorities of NiFe film with small saturation magnetic field and NiCo material with large AMR,unfolds the research of magnetic multilayer angle sensor.Through the study of the influence of thickness ratio and period number of each film on the anisotropic magnetoresistance,an angle sensor with high sensitivity and high AMR effect is realized.The concrete research proceedings are as follows:Firstly,the influence of different thickness ratio of NiFe and NiCo on magnetic properties was studied.Ta/NiFe(x)/NiCo(40-x)/Ta magnetic films on Si substrates were deposited by magnetron sputtering.Through the series changes of NiFe and NiCo thickness,according to the AMR,hysteresis loop and XRD measurements,it was found that structure of NiFe/NiCo magnetic multilayers can effectively reduce the saturation field and coercivity field of the films.It was found that the saturation field and coercivity field of NiFe/NiCo magnetic multilayers can be effectively reduced on the premise of high AMR.When the thickness of NiFe and NiCo were equal,the AMR effect of the films is up to 2.3%,and the coercivity and saturation fields are 4.6Oe and15Oe.The thickness of NiFe and NiCo is the best proportion in the follow-up study.Secondly,under the condition of NiFe and NiCo thickness proportion in 1:1,the variation of different number of periods on the properties of multilayer films was investigated.Ta/[NiFe/NiCo]n/Ta magnetoresistance films(n=1,2,4,6,8)were prepared.Through the comprehensive analysis of AMR,hysteresis loop,XRD and AFM,found out that the coercivity field of the films decreased with the increase of the period number,in the meanwhile ensuring high AMR.And the comprehensive performance was the best when n=4,which established the material foundation for bringing about the angle sensor with low saturation field and large magnetoresistance change rate.Finally,the AMR angle sensor based on magnetic multilayers were designed and fabricated.Explored the different period films has what kind of influence on the performance of the sensor,as well as the angle error,orthogonal error and fitting were analyzed based on the voltage output curve of the sensor.The angle sensor based on[NiFe/NiCo]₄multilayer film has the best comprehensive performance,and the angle error can reach±0.8°.The AMR angle sensor based on[NiFe/NiCo]₄multilayer film has the best comprehensive performance,and the angle measurement accuracy can reach±0.8°.Compared with NiFe(40nm)and NiCo(40nm)angle sensors,the angle resolution of the magnetic multilayer angle sensor is better than that of NiFe(40nm)single-layer angle sensor,and the saturation field is equivalent.Compared with NiCo(40nm)single-layer angle sensor,the saturation field decreases from 200Oe to 125Oe by 38%.Therefore,the magnetic multilayer proposed in this study can reduce the overall volume and improve the performance of the anisotropic sensor unit,and satisfy the current development demands of angle sensor with high integration,miniaturized size,lightweight,low saturation field and sensitivity in above of average level.