Fabrication and characterization of MgO-based magnetic tunnel junctions for spin momentum transfer switching

Current-induced spin-torque switching was demonstrated on sub-100 nm magnetic tunnel junction devices fabricated on 200 mm substrates utilizing 180 nm complimentary metal-oxide-semiconductor back-end-of-the-line (BEOL) technology. Low resistance-area (RA) product and high tunneling magnetoresistance (TMR) were achieved by using substrates containing a CoFeB free layer and a thin MgO barrier. To obtain the desired sub-100 nm features, photoresist trimming was applied on patterns created by a 248 nm lithography tool. Furthermore, the magnetic stack was defined using an ion beam etch that stopped on the thin MgO barrier. Field-sweep measurements on elliptical devices that are 80 nm wide and 160 nm long indicated RA∼4 μ m2 and TMR∼90%. Upon injecting current into the devices while applying an external offset field of 28 Oe, current-induced switching occurred from parallel (P) to antiparallel (AP) state at +1.3 mA, and from AP to P state at -1.25 mA. BEOL process integration on 200 mm substrates enabled statistical analysis of device properties, such as the observation of two breakdown mechanisms in the devices. © 2007 American Institute of Physics.