Electrical breakdown of the magnetic tunneling junction with an AlOx barrier formed by radical oxidation

Abstract

In this work, the dielectric breakdown in magnetic tunnel junctions ͑MTJs͒ was studied. The MTJ structure is Ta50/NiFe100/Co20/AlOx/Co30/RuRhMn100/Ta50 with the bottom lead of Ta50/ Cu500/Ta50 and the top lead of Cu2000/Ta50 ͑in Å͒, where the tunneling barrier was formed by 2-20 min radical oxygen oxidation of a 10 Å-thick Al layer. The junctions with area from 2ϫ2 to 20ϫ20 m 2 were patterned using the photolithography process, leading to tunneling magnetoresistance up to 17.2% and resistance-area product ranging from 350 ⍀ m 2 to 200 k⍀ m 2 . The junctions studied show dc breakdown voltage from 0.7 to 1.3 V, depending on the junction area and the oxidation time. Long oxidation time up to 14 min and a small junction area results in a large dc breakdown voltage. The electrostatic discharge ͑ESD͒ of MTJs was tested by using a human body model. The ESD breakdown voltage increases with decreasing junction resistance. These results are discussed in terms of the E-model based on the field-induced distortion of atomic bonds in the oxide barrier.

Electrical stress effect on Josephson tunneling through ultrathin AlOx barrier in Nb/Al/AlOx/Nb junctions

“…[5,6,7,8,9] The existence of both intrinsic and extrinsic breakdown modes was suggested. [7] The intrinsic mode was associated with a hard breakdown, and was suggested to be related to the chemical bond breaking in applied electric field.…”

Difference between chemical structures of the interface at the Al-oxide tunneling barrier prepared by plasma or by radical oxidation

“…Various oxidation methods, such as natural oxidation [3], radio frequency (RF) plasma oxidation [4,5], and radical oxidation [6,7], have been explored to obtain an Al-oxide tunneling barrier of high quality. Of those methods, plasma www.elsevier.com/locate/apsusc Applied Surface Science 253 (2007) 7632-7638 oxidation has been the most popular to fabricate the Al-oxide barrier because it requires less oxidation time and produces MTJs with better characteristics than those fabricated by natural oxidation [5].…”

Magnetic Random Access Memory for Embedded Computing

“…In order to sense the resistance of the MTJ we must apply a voltage across it and allow current to pass through. For improved signal-to-noise ratios the applied voltage (and current) should be increased, but doing so will increase power consumption and bias voltages across the MTJ should be kept well below 1 V to insure long term reliability [122][123][124][125][126].…”