Ion bombardment effect on properties of MoOx thin film under different PEALD plasma exposure time

Abstract

Molybdenum oxide (MoO x ) films have been prepared by using Mo(CO) 6 precursor and remote oxygen plasma reactant via plasma enhanced atomic layer deposition (PEALD) system. The influence of plasma exposure time on the optical, structural, morphological and chemical composition characteristics of the MoO x thin films have been elaborated systematically. The results show that both the plasma oxidizing reaction and ion bombardment effect exist during the films' deposition. Three kinds of different precursor deposition mechanisms of PEALD-MoO x thin films have been proposed firstly and analyzed in detail under different plasma duration, namely unsaturated reaction, saturated reaction and ion bombardment effect. The film growth rate increased with the increment of plasma exposure time and reached a maximum value at 28 s, which manifested the film growth dominated by the plasma oxidizing reaction in this stage and the transformation from unsaturated reaction to saturated reaction. As the further increase of plasma exposure time from 33 to 38 s, the ion bombardment effect couldn't be ignored and led to the formation of more oxygen vacancy defects along with the decrease of refractive index and growth rate. The clarification of the balance mechanism between oxygen radicals' supply and ion bombardment damage is very important for the achievement of high quality MoO x films. • The effect of plasma exposure time on properties of MoO x film has been explored. • Both oxidizing reaction and ion bombardment effect exist during films'deposition. • Three kinds of precursor deposition mechanism have been proposed firstly.