NOVELTY - The method involves providing a semiconductor substrate (102) comprising a multi-layer resist to a process chamber, where the resist has a patterned photoresist layer defining a set of features e.g. trenches, to be etched into the substrate arranged above a silicon-based antireflective layer or coating. The silicon-based antireflective layer or coating is etched (108) through the patterned photoresist layer by utilizing plasma formed from process gas having a primary reactive agent including chlorine-containing gas or chlorine.    USE - Method for etching a silicon-based antireflective layer or coating to process a semiconductor substrate for an integrated circuit. Uses include but are not limited to silicon substrate, III-V compound substrate, silicon germanium substrate, epi-substrate, silicon-on-insulator (SOI) substrate, display substrate such as LCD substrate, plasma display substrate, electro luminescence (EL) lamp display substrate, LED substrate, solar cell array substrate, solar panel substrate and semiconductor wafer i.e. silicon wafer.    ADVANTAGE - The method enables etching the antireflective layer or coating by using the plasma formed from the process gas instead from the fluorocarbon based etch chemistry, thus increasing productivity and efficiency of processing the substrate by reducing a critical dimension of features and providing an increased etch rate of the anti-reflective layer or coating.    DETAILED DESCRIPTION - The process gas is one of oxygen, hydrogen, fluorocarbon selected from a group of tetrafluoromethane, hexafluoroethane or octafluorocyclobutane, and hydrofluorocarbon selected from a group of difluoromethane, methane or trifluoromethane. The method enables using inert gas selected from one of nitrogen, helium or argon.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart illustrating a method for processing a semiconductor substrate.    Method for processing semiconductor substrate (100)    Step for providing substrate (102)    Step for providing process gas (104)    Step for forming plasma from process gas (106)    Step for etching silicon-based antireflective layer or coating (108)