Study Of Magnetic Property Of Deposited CoFeB Thin Film Based On Rf Magnetron Sputtering

Recently,due to its low coercivity,low damping coefficient,high spin polarization rate,high saturation magnetization,CoFeB thin film is widely used in many fields,especially as the ferromagnetic layer used in magnetic tunnel junctions.As the basic unit of magnetic random access memory,the performance of the magnetic tunnel junction,such as tunneling magnetoresistance?TMR?,critical switching current density of magnetization reversal,power consumption,etc.,is strongly related to the type,structure size,and preparation process of the magnetic tunnel junction ferromagnetic layers.Therefore,how to improve the performance of CoFeB thin film by optimizing its deposition process is of great significance.In this paper,RF magnetron sputtering was used to deposited CoFeB thin film,and the problem of difficulty in depositing magnetic thin film stably was solved by introducing strong magnetic targets and reducing the thickness of the target materials.The effect of deposition processes and annealing processes on the properties of Co₆₀Fe₂₀B₂₀0 thin film were studied in detail.The main work are as following:The effect of thin film deposition process on the morphology and soft magnetic properties of Co₆₀Fe₂₀B₂₀0 thin film was studied.The process parameters include sputtering power,sputtering pressure and sputtering time.The mechanism of the influence of sputtering parameters on the growth of thin films was analyzed.And the subsequent experimental results validated the analytical theory.The optimum Co₆₀Fe₂₀B₂₀0 thin film sputtering process was obtained as:the base pressure of chamber was 7�10^-44 Pa,the flow rate of argon was 20sccm,the sputtering power was 90 W,the sputtering pressure was 0.3 Pa and the sputtering time was 12 min.The Co₆₀Fe₂₀B₂₀0 thin films deposited under the optimum sputtering parameters have good surface topography,good thin film consistency,low roughness and excellent soft magnetic properties.The coercivity of the Co₆₀Fe₂₀B₂₀0 thin film was 42.1 Oe and the saturation magnetization achieved 1132.4 emu/cm³.The effect of vacuum annealing process on the morphology and soft magnetic properties of Co₆₀Fe₂₀B₂₀0 thin film was investigated.The annealing temperature was controlled.The best annealing process was obtained as:the pressure of chamber was 13 Pa,the annealing temperature was 300?and the annealing time was 1h.The annealed Co₆₀Fe₂₀B₂₀0 thin film had excellent crystal structure,the grain size was fine,the surface of the thin film was smooth,and there was no obvious particle material.Annealing treatment increased the soft magnetic properties of the Co₆₀Fe₂₀B₂₀0 thin films.The coercivity of the Co₆₀Fe₂₀B₂₀0 thin film was 31.9 Oe and the saturation magnetization reached 1257.1 emu/cm³.