Microwave plasma-assisted ALD of Al2O3 thin films: a study on the substrate temperature dependence of various parameters of interest

Abstract

This study utilizes microwave plasma-assisted atomic layer deposition (MPALD) in remote mode to deposit Al2O3 thin films with increased growth per cycle (GPC). Optical emission spectroscopy (OES) was used to identify the plasma configuration in the ALD chamber. MPALD–Al2O3 thin films were deposited at temperatures ranging from room temperature to 200 °C and the electrical parameters were investigated with Al/Al2O3/p–Si metal oxide semiconductor (MOS) structures. A GPC of 0.24 nm was observed for the films deposited at room temperature. The fixed oxide charge densities (Nfix) in all films were of the order of 1012 cm−2. The interface state density (Dit) exhibited a distinct minimum for the films deposited at 100 °C. The dependence of built-in voltage, Nfix, and Dit on Al2O3 deposition temperature was investigated. This can be used as a measure of the electrical applicability of these thin films.