Etching kinetics and dielectric properties of SiOC films exposed to Ar and CF4 plasmas

The investigation of both etching and damage mechanisms for SiOC thin films treated in Ar and CF4 plasma was carried out. It was found that CF4 plasma provides systematically higher SiOC etching rates (due to the domination of chemical etching pathway) as well as is featured by decreasing effective reaction probability for F atoms toward higher input powers (due to a decrease in the fraction of free adsorption sites for F atoms and/or in their sticking coefficient). It was shown that any SiOC etching process always leads to an increase in the dielectric constant, and the situation appears to be worse in the case of Ar plasma. From plasma damage evaluation experiment, it was suggested that the main damage mechanism is the destruction of Si-C bonds by the ion bombardment and ultra-violet (UV) radiation. In the case of CF4 plasma, the fluorination of SiOC surface enforces the destructive impact of ion bombardment through a decrease in the corresponding threshold energy.