A new rf plasma oxidation method for the insulating AlOx barrier in magnetic tunneling junctions

Abstract An rf remote plasma oxidation technique to form an insulating barrier was carried out to enhance properties of CoFe/AlO x /CoFe magnetic tunneling junctions. The rf remote plasma method was found to reduce self-bias effect on the barrier during the rf oxidation process and to increase atomic oxygen concentration in a plasma state. Experimentally observed rms roughness of the barrier in our magnetic tunnel junction was decreased from 5 to 1.5 A. In addition, electrical breakdown voltage and magnetoresistance of our magnetic tunnel junction devices were increased from 0.8 V up to 1.2 V and from 7% up to 30%, respectively.