Reactive ion etching

A method for reactive ion etching an article which comprises a substrate and a surface thereon selected from the group of silicon oxides, silicon nitride, silicon oxynitride, and mixtures thereof which comprises:

• positioning the article to be etched on a cathode;
• enclosing in a container, the cathode and the surface to be etched;
• introducing an etchant gas into said container wherein said gas is a mixture of gaseous fluorocarbon which is capable of supplying CF.sub.3, and a second gas capable of supplying hydrogen selected from the group consisting of hydrogen, NH.sub.4, gaseous saturated aliphatic hydrocarbons, and mixtures thereof, wherein the fluorocarbon is present in an amount sufficient to provide etching of said surface and the second gas is present in an amount sufficient to provide at least about 10% H.sub.2 based on the total molecular flow rate of the gases as measurable by volume per unit time and being sufficient to selectively etch said surface at a greater rate than said substrate without causing polymerization on said substrate, wherein the gases are regulated by individual molecular flow rates prior to mixing together;
• and
• applying an AC potential to the cathode to disassociate the reactive gases and to accelerate chemically reactive etchant gas ions toward said cathode.