Degradation and breakdown of 0.9 nm EOT SiO/sub 2/ ALD HfO/sub 2/metal gate stacks under positive constant voltage stress

By means of leakage current measurements, charge pumping and TDDB analysis, we construct a consistent model for the degradation and breakdown of 0.9 nm EOT atomic layer deposited (ALD) HfO
₂
. During degradation, traps and two-trap clusters are formed in the HfO
₂
giving rise to considerable SILC. The two-trap clusters subsequently wear out, finally leading to an abrupt hard breakdown. We demonstrate that 0.9 nm EOT ALD HfO
₂
is intrinsically reliable under constant voltage stress if hard breakdown is used as a failure criterion