Influence of plasma power on deposition mechanism and structural properties of MoOx thin films by plasma enhanced atomic layer deposition

Abstract

In this study, amorphous films of molybdenum oxide (MoOx) had been prepared by plasma enhanced atomic layer deposition (PEALD) technique using molybdenum hexacarbonyl (Mo(CO)6) as a metal precursor and the mixture gas of O2/Ar as reactants. The influence of plasma power from 1000–3000 W on PEALD-MoOx films’ structure properties was investigated, and the deposition mechanism was proposed. Based on the results, the plasma power playing a crucial role in depositing MoOx films is concluded. A maximum deposition rate of MoOx films is 0.76 Å/cycle, which is achieved at the optimal plasma power of 2000 W owing to the enhancement of plasma radicals’ intensity. The Mo5+ and Mo6+ oxidation states that emerged in all the films were illustrated by x-ray photoelectron spectroscopy studies, which means oxygen deficiency in substoichiometric MoOx films. The proportion of no-lattice oxygen decreases first and then increases with the increase of the plasma power. A low power and a high power may lead to deficient oxidation and obvious ion bombardment effect, respectively, which lead to the reduction of MoOx film quality, as indicated by the refractive index, atomic force microscopy, and scanning electron microscopy. The clarification of the effect of plasma power on PEALD-MoOx thin films is greatly beneficial to the application in high performance electronic devices.