Electron-Impact Ionization of TiClx (x=1-4)

Titanium-tetrachloride, TiCl4, is the precursor of choice for the plasma- assisted chemical vapor deposition of TiN. Efforts to understand and model the key plasma-chemical reactions that lead to the deposition of TiN require a knowledge of the ionization properties of the TiCl4 parent molecule as well as of the TiClx (x=1-3) radicals that are produced in the plasma as secondary species. We report the result of absolute ionization cross section measurements for TiCl4 and the TiClx (x=1-3) radicals from threshold to several hundred electronvolts. Two mass spectrometric techniques using either a high-resolution double-focusing mass spectrometer or a time-of-flight mass spectrometer and the fast-beam technique were employed in the experiments. A complete account of all relevant ionization cross sections and appearance energies will be presented at the Conference together with a comparison of the measured cross sections with predictions from semi-empirical and semi-classical calculations. *Work supported in part by the US DOE and by the VW Stiftung, Germany.