Integration of an in situ RIE preclean with a CVD tungsten silicide deposition process

The in situ process capability of native oxide removal affords an advantage over the conventional method of aqueous hydrofluoric acid cleaning prior to a film deposition step. A technique is described in which an in situ predeposition clean with C₂F₆ gas, using reactive ion etching (RIE) prior to tungsten silicide deposition, is employed. This technique allows post-silicide-deposition high-temperature heat treatment and wet oxidation without loss of film adhesion or other obvious degradative effects. Also reported is the use of secondary ion mass spectrometry (SIMS) to show that this procedure has been effective in the removal of the oxide layer prior to silicide deposition. This study includes definition of the RIE etch parameters which provide acceptable etch selectivity of the oxide to silicon, and avoidance of excessive fluoropolymer formation on the silicon surface