Nanoscale (EOT=5.6 nm) nonvolatile memory characteristics using n-Si/SiO2/HfAlO nanocrystal/Al2O3/Pt capacitors

摘要

The charge storage characteristics of the high-kappa HfAlO nanocrystal memory capacitors prepared by atomic layer deposition in an n-Si/SiO2/HfAlO/Al2O3/Pt structure have been investigated after high-temperature annealing treatment. The high-resolution transmission electron microscopy image shows that the diameter of high-kappa HfAlO nanocrystal is <2 nm. The high-kappa HfAlO nanocrystals have been also confirmed by x-ray photoelectron spectroscopy measurement. Due to the formation of high-kappa HfAlO nanocrystals with the high-temperature (similar to 900 degrees C) annealing treatment, a large hysteresis memory window of 3.7 V at a sweeping gate voltage <10 V is observed as compared to that of the as-deposited memory capacitors. A hysteresis memory window of similar to 1.7 V with a small sweeping gate voltage of +/- 5 V is also observed. A small equivalent oxide thickness (EOT) of 5.6 nm is obtained due to the high-kappa memory structure design. A significant memory window of Delta V approximate to 0.7 V at 20 degrees C and Delta V approximate to 0.6 V at 85 degrees C is observed after 10(4) s of retention time, due to the charge confinement in the high-kappa HfAlO nanocrystals.