The charging response of rapidly annealed (800 and 1000C) 4nm-thick HfO2 was compared with that of as-deposited HfO2 on Si by measuring the surface potential of the HfO2 layers after vacuum ultra-violet irradiation with 11.6eV photons. From vacuum ultra-violet spectroscopy, it was deduced that all HfO2 layers exhibited the presence of oxygen-interstitial defects. The electronic states of oxygen-interstitial defects in HfO2 lined up in energy with oxygen-deficient Si centers within the SiO2 interfacial layer. This implied charge exchange between oxygen-interstitial defects within HfO2 and the O-deficient silicon centers within the SiO2 interfacial layer were very important for controlling the radiation-induced trapped charge in HfO2 dielectric stacks.

Effect of Thermal Annealing on Charge Exchange between Oxygen Interstitial Defects within HfO2 and Oxygen-Deficient Silicon Centers within the SiO2/Si Interface. J.L.Lauer, J.L.Shohet, Y.Nishi: Applied Physics Letters, 2009, 94[16], 162907