Materials Engineering for High Performance Ferroelectric Memory

NVDRAM is a high density (32Gb), dual layer 3D stacked, (Hf,Zr)O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -based non-volatile ferroelectric memory. With 5.7nm thin ferroelectric film, NVDRAM offers high performance and robust reliability. Using extensive material characterization and electrical correlations, we demonstrate the effect of phase composition and defect generation on the reliability characteristics of (Hf,Zr)O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -based ferroelectric memory. We show that fatigue is caused by oxygen vacancy generation, and it can be improved by the presence of monoclinic phase. In addition, we report frequency dependent accelerated polarization loss as a critical degradation mechanism. We also show that bipolar AC TDDB increases with orthorhombic phase percentage. We introduce Effective 2Pr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">drop</inf> as the appropriate metric for accurately assessing ferroelectric reliability.