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

Abstract

Long-term reliability results over six orders of magnitude in time are presented showing that the voltage acceleration model for ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> exhibits an exponential dependence with voltage, down to 2 V. The voltage acceleration parameter gamma is between 10 and 15 V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 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- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> film. Under ac stress conditions, this SILC branch is lowered in magnitude, translating to a gain in lifetime to breakdown.