Effect of O- Ion Beam Irradiation during RF-Magnetron Sputtering on Characteristics of CoFeB--MgO Magnetic Tunnel Junctions

The relevance between electrical properties of CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) and the crystalline orientation of MgO layer was investigated within a large-scale substrate. The tunnel magnetoresistance characteristics and the resistance-area product in CoFeB/MgO/CoFeB MTJs are degraded by deterioration of the crystalline orientation of MgO layer, which depends on sputtering conditions. That deterioration originates from damage caused by high-energy oxygen negative-ion irradiation during RF-magnetron sputtering of the MgO layer.