Plasma etching resistance of plasma anisotropic CVD carbon films

Hard carbon films have attracted much attention due to their high hardness and wear resistance. Deposition profile of hard carbon films on trench substrates is one of the concerns to realize coatings on such substrates. Here we have demonstrated three kinds of deposition profiles of carbon films on substrates with submicron wide trenches using H-assisted plasma CVD of Ar + H₂ + C₇H₈. The three deposition profiles are sub-conformal, conformal and anisotropic deposition profile, for which carbon is deposited on top and bottom of trenches without being deposited on sidewall of trenches. Experimental deposition profiles are determined by the balance between deposition of carbon containing radicals and etching by H atoms. Irradiation of ions hardens films and hence decreases the etching rate. When the etching rate surpasses the deposition rate of carbon containing radicals, no deposition takes place there. Therefore, a high H atom flux is the key to anisotropic deposition.