A study on ozone oxidation process in magnetic tunnel junctions

Abstract

Magnetic tunnel junctions with Al_2O_3 barrier layer oxidized by ozone and oxygen mixture gas(ozone atmosphere) were fabricated and Al oxidation characteristics were investigated. The TMR ratio and junction resistance of ozone oxidized junctions were 33% and several KΩμm^2 at the junction area of l0×l0μm^2. In this study, oxidation kinetics and its chemistry were investigated using transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). To study the growth characteristics of Al oxide in ozone atmosphere, the Al layers were oxidized under zero, positive and negative bias conditions. Both positive and negative bias accelerated aluminum oxidation, O/Al ratio was not uniform through the oxide layer grown under positive bias condition.