DLC (Diamond-Like Carbon) is known as amorphous carbon including hydrogen and has a property between graphite and diamond. The property of DLC shows wear resistance, high hardness and low friction coefficient. DLC is applied in various fields such as parts for semiconductor manufacturing or molds. DLC film has been manufactured by various methods.

In this study, DLC films were prepared by the ion-beam assisted method that was the PVD method allowing a low-temperature formation. In this method the mixing layer which led to high adhesion was formed between the substrate and the DLC thin film. DLC films were prepared by He⁺ ion irradiation using various carbon sources, such as ethylene (C₂H₄), toluene (C₇H₈), naphthalene (C₁₀H₈) and dodecane (C₁₂H₂₆). He⁺ ion beam was irradiated at a current density from 5 to 60 μA/cm² with a constant accelerating voltage of 5 kV. Film composition and microstructure were investigated by X-Ray photoelectron spectroscopy and Raman spectroscopy, respectively. The hardness was measured from an indentation method with a Knoop indenter. The friction coefficient was measured for an SUJ2 ball with a constant load of 0.98 N until the sliding distance reached to a length of 100 m.

Use of various carbon sources induced difference in mechanical properties of DLC thin films. In the case of the ethylene and dodecane source without the benzene rings the Knoop hardness showed the maximum value under the condition of 20 μA/cm² and 30 μA/cm² in a current density respectively. The hardness properties of the DLC films prepared by using naphthalene and toluene with benzene rings showed broad curves without the definite peak respectively.