Improvement of performances HfO2-based RRAM from elementary cell to 16 kb demonstrator by introduction of thin layer of Al2O3

Abstract In this article, the reliability of HfO 2 -based RRAM devices integrated in an advanced 28 nm CMOS 16 kbit demonstrator is presented. In order to improve the memory performance, a thin Al 2 O 3 layer is inserted in the HfO 2 -based memory stack (TiN/Ti/HfO 2 /Al 2 O 3 /TiN). Thanks to extensive electrical characterizations on both single layer HfO 2 and bilayer HfO 2 /Al 2 O 3 memory stacks at device and array levels, the potential of the bilayer is put forward. From the experimental results, the thin Al 2 O 3 layer has allowed to improve the endurance (memory window of about one decade after 1 M cycles) and data retention (both the low and the high resistance states are stable after 6 h at 200 °C). Finally, thanks to our 3D model based on calculation of the Conductive Filament resistance using trap assisted tunneling (TAT) the role of Al 2 O 3 as series resistance is highlighted.