電子ビーム励起プラズマ中でのＣ６０フラーレン昇華によるアモルファスカーボン膜の作製

Abstract

C60 fullerene is used as a carbon source for amorphous carbon film deposition in an electron beam excited plasma. C60 powders are sublimated by heating up to 850°C in a highly vacuumed process chamber. The sublimated C60 is injected to the electron beam excited argon plasma and dissociated to be active species that diffuse toward the substrates. Different negative bias voltages have been applied to the substrate holder to examine the effect of the bias voltage to the properties of the films. Consequently, the carbon species condense as a thin film onto the negatively biased substrates that are immersed in the plasma. Deposition rates of approximately 1.0 μm/h and the average surface roughness of 0.2 nm are achieved. Decomposition of the C60 fullerene after injecting into the plasma is confirmed by optical emission spectroscopy that shows existence of small carbon species such as C2 in the plasma. X-ray diffraction pattern reveals that the microstructure of the film is amorphous, while fullerene film deposited without the plasma shows crystalline structure. Raman spectroscopic analysis shows that the films are one of the types of diamond-like carbon films. The nano-indentation technique is used for hardness measurement of the films and results in hardness up to about 28 GPa.