Design And Fabrication Of Microbridge Thin Film Magnetoelectronic Sensor Array

The thin film magnetoelectric sensor has the advantages of low power consumption,small size,easy to integrate,and shows good application prospects in many fields such as weak magnetic field detection.Although,the detection limit of traditional single thin film magnetoelectric sensor at the resonant frequency had reached fTesla,the response bandwidth is very narrow,and its output response drops sharply at the non-resonant frequency.These factors limit the practicality of thin film magnetoelectric sensors.In view of the above situation,the thin film magnetoelectric sensor array with micro-bridge structure is designed and fabricated in this paper.Several identical micro-bridge magnetoelectric units are connected in series to enhance the output response at the non-resonant frequency,and several micro-bridge magnetoelectric units with different structural parameters are connected in parallel to widen the response bandwidth at the resonant frequency.Firstly,Pb?Zr,Ti?O₃?PZT?and FeCoSiB are used as piezoelectric layer and magnetostrictive layer respectively.We proposed a micro-bridge structure thin film magnetoelectric sensor which has strong ability to resist external noise,good process compatibility and easy to integrate.The parameters on the output voltage and resonant frequency of the micro-bridge structure was investigated through finite element simulation.Secondly,PZT and FeCoSiB films with a thickness of 1?m were prepared by Sol-gel and magnetron sputtering.The characterization results showed that the film has good microstructure,electrical properties and magnetic properties.On this basis,a plurality of thin film magnetoelectric units with different microbridge structure parameters were prepared on the same substrate after the optimization of key microelectronic process steps such as etching and insulation layer preparation,and then the magnetoelectric units are connected in series and in parallel to form thin film magnetoelectric sensor array.Finally,performance tests were performed on the single unit and arrayed microbridge structure thin film magnetoelectric sensor.The results showed that the resonant frequency of a single magnetoelectric unit is 7900 Hz,the detection limit is 28 nT,and the maximum magnetoelectric response coefficient at the resonant frequency is 16.87 V/cm·Oe.When three identical magnetoelectric units were connected in series,the sensitivity at the non-resonant frequency was significantly improved,which was 1.65 times that of a single unit.At the same time,the high-precision control of the resonance peak spacing of different magnetoelectric units was realized by adjusting the substrate parameters of the micro-bridge structure without changing the structure of the piezoelectric and magnetostrictive layers.After the two magnetoelectric units whose resonance peaks were regulated were connected in parallel,the 3dB bandwidth was doubled to the original one.This study provides a feasible solution and technical path for the subsequent large-scale integration and arraying of thin film magnetoelectric sensors.