Research On The Preparation Process And Characteristics Of Magnetic Field Sensor Based On MgO Magnetic Tunnel Junction

Magnetic tunnel junction magnetic field sensor as a non-contact sensor,it has a wide range of applications in fields such as automation technology,satellite positioning,and precision measurement,etc.At present,the magnetic properties such as the reluctance change rate need to be further improved.In this paper,the magnetron sputtering method and lift-off technology are used to design and manufacture a magnetic tunnel junction magnetic field sensor based on Mg O barrier.And the structure of the magnetic tunnel junction film from bottom to top is the substrate layer?Si/Si O₂?,bottom electrode layer?Ta?,improved exchange bias layer?Ir Mn?,ferromagnetic layer 1?CoFeB?,tunnel barrier layer?Mg O?,ferromagnetic layer 2?CoFeB?and top electrode layer?Ta?.The Wheatstone bridge is used to connect the magnetic tunnel junctions to form the Mg O magnetic tunnel junction magnetic field sensor.In this paper,multilayer film structures were prepared under different preparation conditions,and the microstructure of the multilayer film was analyzed by X-ray diffraction?XRD?,atomic force microscope?AFM?,step instrument,etc,and summarize the optimized preparation conditions.Using L-Edit software to draw the design scheme of three layouts of magnetic tunnel junction chip,six kinds of tunnel junction area sizes were designed,and integrated chips with different tunnel junction area sizes were also designed.Finally,the sensor chips of each design scheme were packaged without magnetization.In this paper,the magnetic field sensor test system was used to test the characteristics of the chip at room temperature.I-V characteristic test and magnetoresistive characteristic test were carried out using magnetic tunnel junction chips in deposited state and different annealing temperatures.The experimental results show that the tunnel junction area of50×50??m²?shows good I-V characteristics and magnetoresistance characteristics among the six tunnel junction area sizes.The total change of reluctance is 1.491K?,the change rate of reluctance of tunnel junction is 33.6%,and the sensitivity is 1.24?/Gs.Through calculation,the output voltage of the Mg O magnetic tunnel junction magnetic field sensor is changed,and the measurement of the magnetic field signal is realized.