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 $\text{RA}\sim 4\Omega \mu {\text{m}}^2$ and $\text{TMR}\sim 90\%$ . 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 $+1.3\text{mA}$ , and from AP to P state at $-1.25\text{mA}$ . BEOL process integration on 200 mm substrates enabled statistical analysis of device properties, such as the observation of two breakdown mechanisms in the devices.