Effect of discharge power and silicon content on optical and mechanical properties of carbon-rich amorphous silicon carbide films obtained by PECVD

We studied optical and mechanical properties of a-SixC1-x:H films prepared by the PECVD technique from the mixture of CH4, SiH4, H-2 and Ar. RF discharge power and silane flow rate were chosen as parameters of the film deposition process that allowed to vary film properties. It was shown that variations of silane flow rate (10, 20 sccm) and discharge power in the 100-300 W range allow to obtain films with the following characteristics: optical bandgap 2.5-4.1 eV; refractive index of 1.8-2.1; hardness (H) 8.6 -14.8 GPa; Young modulus (E) 64-143 GPa. The film deposition rate varied from 10 to 35 nm/min. By selecting deposition regimes, we deposited films with high ratio between film hardness and Young modulus (H/E = 0.13). The variations of optical and mechanical properties of the films by changing discharge power and silane flow are interpreted within a model accounting film composition and phase-structural transformations. Good combination of optical and mechanical properties of the developed films makes them promising for application as protective, passivation and anti-reflection coatings. (C) 2019 Elsevier B.V. All rights reserved.