Plasma reactions of N2O on hydrogenated amorphous carbon films by PECVD

Diamond-like carbon (DLC, a-C:H) films were deposited by r.f. plasma-enhanced chemical vapor deposition of methane(CH4)–nitrous oxide(N2O)–hydrogen(H2) mixtures onto silicon substrates. Increasing the r.f. power leads to the production of more radicals and to a deposition rate as high as 1380 Å h−1 at r.f. power of 300 W, after which it decreases. As the r.f. power increases, the root-mean-square (RMS) roughness decreases. The RMS roughness of 2.2 Å was obtained at r.f. power of 300 W. The optical properties (the transmittance over a wide spectral range and refractive index) were determined by means of IR-spectroscopy and ellipsometric measurements. Surface morphology of DLC films with roughness below 10 Å was observed under atomic force microscopy.