Abstract: A process of using a-C:H layer as a hardmask material with tunable etch resistivity in a RIE process that alleviates the addition of a layer forming gas to the etchant when making a semiconductor device, comprising: a) providing a semiconductor substrate; b) forming a hardmask of amorphous carbon-hydrogen (a-C:H) layer by plasma enhancement over the semiconductor substrate; c) forming an opening in the hardmask layer to form an exposed surface portion of the hardmask layer; and d) etching the exposed surface portion of the hardmask layer without the addition of a layer forming gas using RIE to form a trench feature with sufficient masking and side wall protection.