Effect of Mo capping in sub-100 nm CoFeB-MgO tunnel junctions with perpendicular magnetic anisotropy

Abstract Co20Fe60B20/MgO/Co20Fe60B20 perpendicular magnetic tunnel junctions with Mo seed and capping layers were patterned into sub-100 nm diameter devices. The resulting devices were imaged in plan view by scanning electron microscopy and in cross-section by scanning transmission electron microscopy. The tunnel magnetoresistance was ∼125%. The coercivity dropped off below 35 nm, and the stray field increased with decreasing diameter. The voltage controlled magnetic anisotropy effect was observed for all sizes, though it was convoluted with thermal and stray field effects for the smaller diameters.