METHOD FOR ETCHING SILICON OXYNITRIDE AND DIELECTRIC ANTIREFLECTION COATINGS

摘要

The present disclosure pertains to a method for plasma etching a semiconductor film stack. The film stack includes at least one layer comprising silicon oxynitride. The method includes etching the silicon oxynitride-comprising layer using an etchant gas mixture comprising chlorine and at least one compound containing fluorine and carbon. The atomic ratio of fluorine to chlorine in the etchant gas ranges between about 3:1 and about 0.01:1; preferably, between about 0.5:1 and about 0.01:1; most preferably between about 0.25:1 and about 0.1:1. The etchant gas forms a fluorine-comprising polymer or species which deposits on exposed surfaces adjacent to the silicon oxynitride-comprising layer in an amount sufficient to reduce the etch rate of an adjacent material (such as a photoresist) while permitting the etching of the silicon oxynitride-comprising layer.