A layer of material (14) comprising silicon, such as an SiO.sub.2 layer, overlying a silicon substrate (12) of a semiconductor device (10), is dry etched without the need for traditional halocarbon gases (such as CHF.sub.3, CF.sub.4, and C.sub.2 F.sub.6) which are known green-house gases. A fluorine source, for producing the active fluorine radicals needed to etch silicon, is selected from either HF or F.sub.2 gases. A carbon-oxygen source, for providing and stabilizing polymer build-up in the reactor, is selected from either CO or CO.sub.2. An additional hydrogen source may be added as needed.