Thickness and temperature dependences of the degradation and the breakdown for MgO-based magnetic tunnel junctions

Abstract

The reliability of a magnetic tunnel junction (MTJ) with an MgO tunnel barrier was evaluated. In particular, various voltage tests were used to investigate the effects of the barrier thickness and the temperature on the resistance drift. We compared the resistance change during a constant voltage stress (CVS) test and confirmed a trap/detrap phenomenon during the interval stress for different barrier thicknesses and temperatures. The resistance drift representing degradation and the time to breakdown (TBD) representing the breakdown characteristic were better for a thicker barrier and lower temperature, but were worse for a thinner barrier and a higher temperature. The results suggest that breakdown and degradation due to trap generation strongly depend on both the barrier thickness and the temperature. Furthermore, as the TBD varies at steady rates with changing barrier thickness, temperature, and electric field, we assume that a MTJ with an adnormal thin layer of MgO can be screened effectively based on the predicted TBD. As a result, the barrier thickness and the temperature are very important in determining the reliability of a MTJ, and this study is expected to be helpful in understanding the degradation and the breakdown of a MTJ.