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.