Effects of radio-frequency power on the properties of carbon thin films prepared by thermal chemical vapor deposition enhanced with remote inductively-coupled-plasma using acetylene/nitrogen mixtures

• Carbon films are prepared by TCVD enhanced with remote ICP using C2H2/N2 mixtures.
• The deposition rate of carbon thin films decreases with increasing the rf-power.
• C2H, C2H2, and C2H4 are speculated as the main species for carbon film deposition.
• The sp2 sites in carbon thin films decrease with increasing rf-power.
• Young's modulus and hardness of carbon films increase with increasing rf-powers.

The effects of radio-frequency (rf) power on the properties of carbon thin films prepared by thermal chemical vapor deposition (CVD) enhanced with remote inductively-coupled-plasma (ICP) are investigated. Acetylene and nitrogen were used as the precursor gases, and rf-powers of ICP were set as 0, 100, 200, 300, and 400 W. The deposition temperature, working pressure, and deposition time were set as 1248 K, 4 kPa, and 2 h, respectively. The residual gases, film thicknesses, microstructures, chemical characteristics, mechanical properties, and electrical properties of carbon thin films were investigated by residual gas analyzer (RGA), field emission scanning electron microscopy, X-ray diffractometer (and Raman scattering spectrometer), X-ray photoelectron spectrometer, nanoindenter, and four point probe, respectively. RGA results reveal that the main species in the gas phase contain H2, C2H, C2H2, HCN (or C2H3), and N2 (or C2H4). Moreover, C2H, C2H2, and C2H4 can be speculated as the main species for carbon thin film deposition. As the rf-power increases from 0 to 400 W, the deposition rate of carbon thin films decreases from 204 to 36.0 nm/h. The crystallinity and ordering degree of carbon thin films increase with increasing rf-power from 0 to 400 W, but the ratio of sp2 carbon sites in carbon thin films decreases from 95 to 75%. The Young's modulus, hardness, and electrical resistivity of carbon thin films increase with increasing rf-power. Furthermore, the effects of rf-power on the deposition rates of carbon thin films prepared by thermal CVD enhanced with remote ICP using C2H2/N2 and CH4/N2 mixtures are compared.