Deposition of diamond-like carbon films by barrier discharge plasma with 1.4 and 20 kHz power sources

Hydrogenated diamond-like carbon (DLC) films were deposited on Si substrates at 1.4 and 20 kHz a.c. power frequencies by dielectric barrier discharge (DBD) technology. Atomic force microscope analysis showed that the roughness parameter R q changed from 0.27 to 0.107 nm with decreasing the deposition pressure from 2.48 to 1.65 Torr. The charge-coupled device camera images and measurements of high-voltage and current waveforms of the DBD plasma indicate that the low-pressure DBD consists of spatially uniform glow-like single breakdowns that contribute to the formation of smooth surfaces of the deposited films. Fourier transform infrared spectroscopy analysis and hardness measurement results showed that the properties of the films deposited at 20 kHz power frequency changed from those of graphite-like to diamond-like to polymer-like with increasing the deposition pressure from 1.12 to 2.48 Torr. Increasing the power frequency from 1.4 to 20 kHz may cause an increase of the deposition rate from 4.5 to 26 nm/min. The higher breakdown voltage at 20 kHz power frequency may produce hydrocarbon ions with higher energies in the cathode sheath near the substrates, which would have much effect on hardness of the deposited DLC films.