Effect of buffer layer for HfO2 gate dielectrics grown by remote plasma atomic layer deposition

Abstract

Three different buffer layers on a Si substrate were grown to investigate the interfacial layer effect during HfO2 deposition and thermal annealing. The three different buffer layers were the very thin Al2O3, remote plasma nitridation (RPN)-treated Al2O3, and RPN-treated HfO2 films. HfO2 films were then grown on these three different buffer layers by a remote plasma atomic layer deposition method. The HfO2 films with RPN-treated buffer layers retarded silicate formation or growth of an interfacial layer more effectively than those without RPN treatment. The HfO2 films with an RPN-treated HfO2 buffer layer showed the lowest effective oxide thickness and those with an RPN-treated buffer layer exhibited low leakage current density. The effective fixed-oxide charge density of the HfO2 film with an RPN-treated HfO2 buffer layer showed the lowest value of 3.60 x 10(11)/cm(2) compared to the other films. As the annealing temperature increased, the flatband voltage (V-FB) for the HfO2 films was shifted and became close to the ideal VFB. The interface stability of HfO2 with a nitrided buffer layer formed by RPN treatments resulted in the improvement of the electrical properties of HfO2 films.