Time‐to‐breakdown characteristics of magnetic tunnel junctions

Abstract

To investigate the reliability of the MTJs on the roughness of insulating tunnel barrier, we prepared two MTJs with the different uniformity of barrier thickness. Namely, the one has uniform insulating barrier thickness; the other has non-uniform insulating barrier thickness as compared to different thing. As to depositing amorphous layer CoZrNb under the pinning layer IrMn, we achieved MTJ with uniform barrier thickness. First of all, we performed the breakdown-voltage measurement of two junctions and obtained the result having a similar breakdown-voltage about 1.4 V at two all junctions. And then, the time dependence dielectric breakdown (TDDB) measurements of two junctions are carried out under constant voltage stresses. The Weibull fit of our data shows clearly that time to breakdown (t BD ) scales with the thickness uniformity of tunnel barrier. And also, Assuming a linear dependence of log(t BD ) on stress voltages, we meet with result about the different lifetime of the two MTJs with uniform barrier thickness or non-uniform barrier thickness.