Diamondlike carbon thin film fabrication by plasma-enhanced chemical vapor deposition using CH4/N2 gas mixtures for use as a hard mask

Diamondlike carbon (DLC) thin films have been deposited by plasma-enhanced chemical vapor deposition on silicon wafers with methane as a precursor gas and nitrogen as a balancing gas. The optimization of DLC deposition was carried out by varying the experimental parameters of chamber pressure, rf plasma power, and flow rate of the precursor gas. Energy-dispersive spectroscopy of the layers was used to determine the elemental analysis of the DLC thin films. Micro-Raman spectroscopy was used to determine the ratio of disordered graphite from the DLC in the films and to identify the optimal deposition conditions. The surface morphology for the optimum reaction condition was investigated by atomic force microscopy. Chemical stability tests have been performed systematically and have shown that the DLC films are chemically stable with common semiconductor processing chemicals. The films can be removed using oxygen plasma treatment. Ion-coupled plasma/reactive ion etching was performed on the films having almost vertical sidewalls with no trenching at the corners of the pattern. Our DLC films are, therefore, a great candidate as a hard mask for plasma etching.