Deposition and characterization of diamond-like carbon films by microwave resonator microplasma at one atmosphere

Abstract

Diamond-like carbon (DLC) films have been deposited at atmospheric pressure by microwave-induced microplasma for the first time. Typical precursor gas mixtures are 250ppm of C2H2 in atmospheric pressure He. Chemically resistant DLC films result if the Si (100) or glass substrate is in close contact with the microplasma, typically at a standoff distance of 0.26mm. The films deposited under this condition have been characterized by various spectroscopic techniques. The presence of sp3 CH bonds and ‘D’ and ‘G’ bands were observed from FTIR and Raman spectroscopy, respectively. The surface morphology has been derived from SEM and AFM and shows columnar growth with column diameters of approximately 100nm. Likely due to the low energy of ions striking the surface, the hardness and Young's modulus for the films were found to be 1.5±0.3GPa and 60±15GPa respectively with a film thickness of 2μm. The hypothesis that a high flux of low energy ions can replace energetic ion bombardment is examined by probing the plasma. Rapid deposition rates of 4–7μm per minute suggest that the method may be scalable to continuous coating systems.