Molecular dynamics simulations on the direct sputtering of Al ₂O₃ insulating film in a magnetic tunneling junction

The molecular dynamics (MD) simulation is used to study the direct deposition of aluminum-oxide (Al₂O₃) to grow an insulating thin film on cobalt substrate in a magnetic tunneling junction (MTJ). The direct deposition of Al₂O₃ may produce a very thin film with very smooth surface and form an averagely oxidized insulator. A high magnetoresistance ratio is desired in an MTJ device, so that smooth surface and good structural integrity for the insulating thin film is anticipated. The MD simulation is an effective way in determining optimal processing parameters that can be used to fabricate high-quality MTJ devices. The Buckingham and many-body tight-binding potentials are applied in the MD simulations for different interactions between particles. The effects of the cluster size and the incident energy on the thin film's surface morphology and Al₂O₃ purity are investigated. Some optimal parameters that could be used as the reference for practical processing purposes are derived.