First Insight Into the Lifetime Acceleration Model of High-$k$ $hbox{ZrO}_{2}/hbox{SiO}_{2}/hbox{ZrO}_{2}$ Stacks for Advanced DRAM Technology Nodes

Long-term reliability results over six orders of magnitude in time are presented showing that the voltage acceleration model for $hbox{ZrO}_{2}/hbox{SiO}_{2}/hbox{ZrO}_{2}$ exhibits an exponential dependence with voltage, down to 2 V. The voltage acceleration parameter $gamma$ is between 10 and 15 $hbox{V}^{-1}$, depending on the biasing polarity. Soft-breakdown behavior (SILC) is evident prior to the onset of hard breakdown as a result of barrier lowering or charge accumulation in the high- $k$ film. Under ac stress conditions, this SILC branch is lowered in magnitude, translating to a gain in lifetime to breakdown.