Embodiments herein provide methods of depositing an amorphous carbon layer using a plasma enhanced chemical vapor deposition (PECVD) process and hard masks formed therefrom. In one embodiment, a method of processing a substrate includes positioning a substrate on a substrate support, the substrate support disposed in a processing volume of a processing chamber, flowing a processing gas comprising a hydrocarbon gas and a diluent gas into the processing volume, maintaining the processing volume at a processing pressure less than about 100 mTorr, igniting and maintaining a deposition plasma of the processing gas by applying a first power to one of one or more power electrodes of the processing chamber, maintaining the substrate support at a processing temperature less than about 350° C., exposing a surface of the substrate to the deposition plasma, and depositing an amorphous carbon layer on the surface of the substrate.