A comparison between HfO_2/Al_2O_3 nano-laminates and ternary Hf_xAl_yO compound as the dielectric material in InGaAs based metal-oxide-semiconductor (MOS) capacitors

摘要

We compare the electrical properties of HfO_2/Al_2O_3 nano-laminates with those of the ternary Hf_xAl_yO compound in metal oxide semiconductor (MOS) capacitors. The dielectrics were deposited by atomic layer deposition on InGaAs. Water, ozone, and oxygen plasma were tested as oxygen precursors, and best results were obtained using water. The total dielectric thickness was kept constant in our experiments. It was found that the effective dielectric constant increased and the leakage current decreased with the number of periods. Best results were obtained for the ternary compound. The effect of the sublayer thicknesses on the electrical properties of the interface was carefully investigated, as well as the role of post-metallization annealing. Possible explanations for the observed trends are provided. We conclude that the ternary Hf_xAl_yO compound is more favorable than the nano-laminates approach for InGaAs based MOS transistor applications.