Formation of Al2O3 Barrier in Magnetic Junctions on Different Substrates by O2 Plasma Etching

Abstract

Co/Al2O3/NiFe and CO/Al2O3/Co tunnel junctions were fabricated by a radio frequency magnetron sputtering at room temperature with hard mask on glass and 4° tilt cut Si (111) substrates. The barrier layer was formed through two steps. After the Al layer was deposited, it was oxidized in the chamber of a reactive ion etching system (RIE) with O2 plasma at various conditions. The dependence of the TMR value and junction resistance on the thickness of Al layer (before oxidation) and oxidation parameters were investigated. Magnetoresistance value of 7% at room temperature was obtained by optimizing the Al layer thickness and oxidation conditions. Circular shape junctions on 4° tilt cut Si (111) substrate showed 4% magne