Structural and Electrical Properties of (CoxFe100-x)81B19/MgO(CoxFe100-x)81B19 Magnetic Tunnel Junctions

CoFeB layer with amorphous structure has attracted much attention due to its soft magnetic properties and the realization of large tunnel magnetoresistance (TMR) ratio at room temperature when used as the free layer in ferromagnet/insulator/ferromagnet magnetic tunnel junctions. Two types of multilayer films were prepared in this study. Type I is a full stack of MTJs to evaluate the transport properties, while type II is a partial stack of MTJ to analyse the crystalline structure of the reference layer (RL). The films were prepared on a thermally oxidized silicon wafer using a Canon ANELVA C-7100 sputtering system. All the metallic films were deposited using dc magnetron sputtering method. The CoFeB film composition was analyzed by inductive-coupled plasma spectroscopy method. The insulating MgO layer was deposited by rf sputtering directly from a sintered MgO target. After the film deposition, they were annealed at 360 C for 2 hours in a magnetic field of 8 kOe.