The etching mechanism of titanium polycide in a mixture of SF6 and O2

Reactive ion etching of titanium disilicide films on top of undoped polycrystalline silicon has been investigated in order to determine the etching mechanism of the silicide in a fluorine plasma. Mixtures of SF6 and O2 and of CF4 and O2 were used. Vertical and lateral etch rates have been determined as a function of pressure and the amount of oxygen addition. The density of fluorine atoms and positive ions in the plasma has been determined from optical emission spectroscopy and electric probe measurements, respectively. From these results, the fluxes of fluorine to and away from the sample and the ion flux towards the sample have been calculated. With x‐ray photoelectron and Auger electron spectroscopy, the surface constitution after etching has been studied. The TiSi2 layer is etched anisotropically, independent of pressure and the addition of oxygen. A relation between the etch rate and the density of fluorine atoms in the plasma is not found, in contrast with results obtained elsewhere [K. C. Cadien, S...