SiO<inf>2</inf>-like film deposited by plasma polymerization of HMDSO + O<inf>2</inf> using repetitive high voltage pulses

Abstract

© 2020, American Coatings Association. Surface properties of SiO2-like films deposited from plasma polymerization of HMDSO + O2 mixture have been investigated. Plasma of the gas mixture was produced using repetitive high voltage pulses at − 3 kV with varied frequency from 100 to 500 Hz. The films were characterized by means of atomic force spectroscopy, spectroscopic ellipsometry, contact angle measurement, and X-ray photoelectron spectroscopy. The film thickness increased linearly with the pulse frequency in the range of 100–400 Hz where the system was in energy-deficient domain. A further increase in the pulse frequency led to the monomer-deficient domain and the linear dependence of the deposition rate terminated. Refractive index of the films were similar to that of SiO2. Refractive index and extinction coefficient values suggested that the films had high density which is related to high fraction of suboxide structure. The total surface energy of the films was not significantly different when varied pulse frequency was used. The surface energy contained high polar component indicating that the polar Si–O groups were dominant in the structure.