Degradation and time dependent breakdown of stressed ferromagnetic tunnel junctions

Ferromagnetic tunnel junctions are very sensitive to degradation and breakd own, due to the ultrathin (similar to1 nm) tunnel barrier. When the junctio n is stressed with a constant current or voltage, a conductance change of t he tunnel junction is observed. Sufficiently high stress will lead to break down of the junction. As in SiO2 gate oxide reliability studies, the Weibul l distribution plot can be obtained from the time to breakdown data. The de pendence of the Weibull function on the area and the stress conditions is s tudied for the Al2O3 barrier of the tunnel junctions. This is the first ste p of a systematic study of reliability, which is an important issue for the use of tunnel junctions in, e.g., magnetic random access memory applicatio ns. (C) 2001 American Institute of Physics.