Effect of bias and hydrogenation on the elemental concentration and the thermal stability of amorphous thin carbon films, deposited on Si substrate

Amorphous carbon films have been deposited with various levels of negative substrate bias and hydrogen flow rates using argon and argon + nitrogen as sputtering gas. The effect of hydrogenation and substrate bias on the final concentration of trapped elements is studied using ion beam analysis (IBA) techniques. The elemental concentrations were measured in the films deposited on silicon substrates with a 2.5 MeV H+ beam and 16 MeV O5+ beam. Argon was found trapped in the non-hydrogenated films to a level of up to ~ 4.6 %. The concentration of argon increased for the films deposited under higher negative bias. With the introduction of hydrogen, argon trapping was first minimized and later completely eliminated, even at higher bias conditions. This suggests the softness of the films brought on by hydrogenation. Moreover, the effect of bias on the thermal stability of trapped hydrogen in the films was also studied. As the films were heated in-situ in vacuum using a non-gassy button heater, hydrogen was found to be decreasing around 400 °C.