Enhanced Reliability of Top-pinned Perpendicular Magnetic Tunnel Junction by Post-oxidation of Sputtered MgO Barrier

ABSTRACTWe proposed an MgO barrier which is fabricated by combination of rf-sputter deposition of MgO film and subsequent in-situ post oxidation (PO). We found that the perpendicular magnetic anisotropy (PMA) of the CoFeB layer formed on this MgO barrier with PO was improved. We also found that a short error rate reduced drastically and a magnetoresistance (MR) ratio increased about 20% for the magnetic tunnel junction (MTJ) with this MgO barrier with PO. In addition, we showed that this MgO barrier with PO has long endurance life compared with conventional sputtered MgO barriers, and has a potential to operate over 1016 write cycles.Furthermore, we have observed that the PO could suppress the Fe diffusion into the MgO barrier and form Fe-O bonding at MgO/CoFeB interface using electron energy-loss spectroscopy (EELS). The obtained results might be involved to the improvement of PMA and MTJ characteristics.

Interface Reaction Behavior between Mn and SiO2 Formed by RF Sputter Deposition

The Present Work Investigated the Effects of Adsorbed Moisture in Substrates on the Growth of a Self-Forming Barrier Layer between Mn and SiO2. In Order to Control the Adsorbed Moisture, the Substrates of TEOS-SiO2/Si Were Pre-Annealed in Vacuum at Various Temperatures. Then, Mn Thin Films Were Deposited on the Substrate with or without Pre-Annealing. The Results of Interface Reaction after Additional Post-Annealing Indicated that an Interface Reaction Layer Becomes Thinner with Decreasing the Adsorbed Moisture in the SiO2Substrates.