Effect of magnetron discharge power on the resistivity and microstructure of carbon films

Amorphous carbon (a-C) films were deposited by DC magnetron sputtering of a graphite target in argon plasma. The dependence of film resistivity and microstructure on sputtering power has been studied in the range 50–650 W. The film structure was examined by Raman spectroscopy and reflective high-energy electron diffraction (RHEED). The surface temperature of the Si–Ti–Al–O ceramic electrically floated substrates placed onto a water-cooled substrate holder was also measured. The surface temperature of substrate can non-controllably increase and reach 300 °C when depositing the carbon film at sufficiently high sputtering power. Two competing processes affect the growing film: an increase in substrate temperature promotes film graphitization, whereas increase in particle energy with an increase in sputtering power results in films disordering. In the range of sputtering power 50–400 W the effect of substrate temperature is predominant, and in the range 400–650 W the effect of particle energy prevails.