"Characteristics of the HfO2 Thin Films Grown by Remote Plasma Atomic Layer Deposition Method on the Plasma Oxidized Si substrate"

Abstract

We investigated the electrical and physical characteristics of HfO2/SiO2/Si structure formed using remote plasma oxygen (RPO) treatment. The surface preparation of Si (100) substrate was performed by RPO process and yielded 0.5-nm-thick SiO2 layer. HfO2films were deposited on both H-terminated and RPO-treated Si substrates by the remote plasma atomic layer deposition (RPALD) method, respectively. HfO2 grown on RPO-treated Si exhibited a linear growth behavior compared to the HfO2 grown on H-terminated Si. The physical and chemical characteristics of HfO2/SiO2/Si gate insulator structure, with effect of RPO pretreatment on Si substrate, were studied using X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). The thickness of interfacial layer for both as-deposited and annealed HfO2films on RPO-treated Si were thinner than films without RPO treatment. These results indicate that RPO-treated samples may effectively retard the diffusion of oxygen atoms or molecules into Si substrate, which results in the increase of the interfacial layer thickness, compared to the samples without the RPO treatment. The electrical properties of thin films were determined using capacitance-voltage (C-V), and current-voltage (I-V) measurements. HfO2/SiO2/Si stack structure showed lower equivalent oxide thickness (EOT) and leakage current density (J/cm2), compared to HfO2/Si structure of the same thickness. The low hysteresis value due to RPO pretreatment results in the interface stability of HfO2 thin films.