Ultrafast annealing process of MTJ using hybrid microwave annealing

Abstract: This paper discovers that the magnetic tunnel junction (MTJ) structure is successfully magnetized with hybrid microwave annealing, confirmed by the tunneling magnetoresistance (TMR) and Coercivity (Hc) results. Hybrid microwave annealing can transform CoFeB into a single crystal and form the Fe-O bond at the interface between CoFeB and MgO without adding an extra magnet. The annealing time is significantly reduced from the original 120 minutes to just 1 minute, allowing for rapid low-temperature annealing of the MTJ structure. The TEM results are used to determine the change in the lattice structure of CoFeB from amorphous to a single crystal, and the EELS result indicates the diffusion distribution of atoms in the MTJ structure. This hybrid annealing process can save a significant amount of fabrication time and is an energy-efficient alternative to the current fabrication process of MRAM.