A study on the growth mechanism and gas diffusion barrier property of homogeneously mixed silicon–tin oxide by atomic layer deposition

Abstract

SiO2 and SnO2 films were deposited using plasma-enhanced atomic layer deposition (PEALD) at low temperature (100 °C), and homogeneously mixed structure (HMS) films consisting of Si, Sn, and O were deposited through a “1st precursor dose – 2nd precursor dose – oxidation”, a new ALD process method for mixing two elements. For a deep consideration of the growth mechanism during the HMS film deposition process, density functional theory (DFT) calculations of the adsorption reactions of the precursors on the surface were conducted. The properties of the thin films such as density, atomic composition, crystallinity, surface roughness, optical transmittance and the water vapor diffusion barrier property were analyzed by XRR, XPS, XRD, AFM, UV-VIS and the electrical Ca test. By changing the dose sequence of the two precursors in the HMS process, various physical/chemical characteristics of the films could be controlled. Also, by adjusting the appropriate amount of Sn in the HMS films, the shortcomings of SnO2 were compensated by the mixed SiO2; and through this process, excellent gas diffusion barrier properties of WVTR ∼ 1.33 × 10−4 g/m2day were secured.