Magnetron Sputtering Deposition Gradient La_1-xSr_xMnO₃ Thin Film And Characterization

Lanthanide manganese oxide belongs to the perovskite crystal structure,has very excellent magnetic and electrical properties,and has a considerable development prospect in the field of microelectronics.It has very outstanding performance applications,such as magnetic probes,magnetic sensors,magnetic storage,etc.However,the compatibility between lanthanide manganese oxide and Si is poor,which has greatly hindered its application.Therefore,in this paper,a La_1-xSr_xMn O₃ thin film was prepared on a single crystal Si substrate by co-sputtering of La Mn O₃ and Sr Mn O₃ dual target materials by magnetron sputtering.By changing different sputtering parameters,we explore the influence of different processes on the growth of La_1-xSr_xMn O₃ thin films on Si substrates.A gradient La_1-xSr_xMn O₃ thin film was designed.The Sr concentration in the thin film showed a continuous gradient change from the single crystal Si interface to the film surface;and the gradient La_1-xSr_xMn O₃ thin film was annealed.The prepared thin film samples were characterized and analyzed by X-ray diffractometer,field emission electron microscope,atomic force microscope,X-ray photoelectron spectrometer,and four-probe resistance tester.The effect of sputtering parameters on the structure of La_1-xSr_xMn O₃ films was investigated.The results show that all La_1-xSr_xMn O₃films have a single perovskite structure,and the La_1-xSr_xMn O₃ films with a sputtering temperature of 550℃,a sputtering pressure of2Pa,and a sputtering time of 12h have a highly preferred orientation in the（110）crystal orientation.The grains on the surface are uniform and dense.At this time,the thickness of the film is about 2μm,and the grain size on the surface of the film is between 30 and 50 nm.And（110）films with preferred orientation can be obtained under most sputtering conditions,indicating that co-sputtering with La Mn O₃ and Sr Mn O₃ single crystal targets is easier to obtain La_1-xSr_xMn O₃ films with preferred orientation on single crystal Si substrates;Keep the sputtering power of the La Mn O₃ target unchanged during the sputtering process,increase the sputtering power of the Sr Mn O₃ target（20～40W）,increase the sputtering rate of Sr,and change the sputtering power of the Sr Mn O₃ target at different times,Gradient La_1-xSr_xMn O₃ thin films with different compositions were obtained.When the total sputtering time is 12h,the sputtering power of Sr Mn O₃ target is 20W sputtering 4h,30W sputtering 4h,40W sputtering 4h,the obtained gradient La_1-xSr_xMn O₃ thin film structure still has a high（110）crystal orientation Diffraction peaks,and the film morphology is better,the grain size is more uniform,XPS can be seen that the Sr content gradually increases from the film interface to the surface.Using four probes to test the electrical properties of the gradient La_1-xSr_xMn O₃ film,it is concluded that as the average Sr doping content increases,the resistivity in the gradient film gradually decreases.The total sputtering time is 12h,the sputtering power of the Sr Mn O₃ target is 20W sputtering for 2h,30W sputtering for 2h,and40W sputtering for 8h,the resistivity in the film is the lowest,and the resistivity in the film is79.60×10^-3?·cm;After annealing,the structure of the gradient La_1-xSr_xMn O₃ changes from a（110）crystal to a preferentially grown film to a polycrystalline film.This is due to the implantation of O ions during the annealing process and the structure of the gradient film at high temperature.Caused by stability.However,after the film was annealed,the surface morphology of the film was optimized,so that the film grains grew and the grain boundaries were reduced;electrical tests were carried out on the annealed film samples,and it was found that suitable annealing conditions would reduce the resistance of the film,The minimum value is reached when the annealing temperature is 600℃.