Plasma etching characteristics of tungsten films are studied in and in discharges. The etch rates are investigated as a function of electrode temperature, oxygen and hydrogen additions, system pressure, and RF power. Relative fluorine atom concentrations are determined by optical emission spectroscopy. Results indicate that tungsten etching is primarily controlled by fluorine atoms generated in the discharge in plasmas or when oxygen is added to the etch gases. In pure , species may play an important role in the etch process. Hydrogen additions scavenge fluorine atoms and generate residues which inhibit etching.