Embodiments of the present disclosure generally relate to a substrate processing chamber, and components thereof, for forming semiconductor devices. The processing chamber comprises a substrate support, and an edge ring is disposed around the substrate support. The edge ring comprises a material selected from the group consisting of quartz, silicon, cross-linked polystyrene and divinylbenzene, polyether ether ketone, Al2O3, and AlN. The material of the edge ring is selected to modulate the properties of hardmask films deposited on substrates in the processing chamber. As such, hardmask films having desired film properties can be deposited in the processing chamber without scaling up the RF power to the chamber.