Deposition of protective coatings in rf organosilicon discharges

Abstract

The paper discusses the deposition of protective coatings ranging from organosilicon plasma polymers to SiO2-like films and hard diamond-like carbon/silicon oxide (DLC : SiOx) coatings in radio frequency capacitively coupled discharges using hexamethyldisiloxane (HMDSO). As a result of the optimization of the deposition conditions it was possible to obtain high performance protective coatings. In the HMDSO/O2 mixture, it was shown that rather than the SiO2-like film a hard cross-linked SiOxCyHz polymer film can be used as a protective coating for polycarbonate. The optimum conditions for the deposition of an almost stress-free film were 17% of HMDSO and dc bias voltage of −240 V. The film hardness and elastic modulus were 10 GPa and 75 GPa, respectively. The refractive index at 600 nm was 1.5 and the extinction coefficient decreased from 0.02 at 240 nm down to zero at 600 nm.