Deposition of Thin Films of SiOxCyH in a Surfatron Microwave Plasma Reactor with Hexamethyldisiloxane as Precursor

Abstract

AbstractThin films of SiOxCyH have been prepared by plasma enhanced (PE)CVD in a surface‐wave, microwave reactor. The films were deposited in direct mode by using hexamethyldisiloxane (HMDSO) as the precursor, and mixtures of oxygen/argon as the plasma gas. Analysis of the plasma by optical emission spectroscopy (OES) showed that, under reaction conditions, the molecules of the precursor are not greatly fragmented in the plasma. This suggests that polymerization occurs after adsorption of the precursor species on the surface of the growing films. The chemical structure and composition of the films were examined by Fourier‐transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). A strong correlation is found between the composition and bonding structure of the thin films and the oxygen:HMDSO ratio in the plasma gas. Raising the oxygen concentration leads to an increase in the growth rate and to the removal of the organic groups from the films that, for O2:HMDSO ratios greater than 0.8, reach a composition close to silicon dioxide. It has been shown that the Auger parameter of silicon determined by XPS depends on the composition of the films (e.g., 1714.5 for O2:HMDSO = 0, and 1712.3 for O2:HMDSO = 0.75). It is shown that this parameter can be taken as a measurement of the polarizability of the films. It is concluded that surfatron launchers are a versatile set‐up for an efficient control of the composition and properties of thin films of SiOxCyH prepared by PECVD.