Selective Silicide or Boride Film Formation by Reaction of Vapor Phase TiCl₄ with Silicon or Boron

Methods for selectively forming titanium silicide and titanium boride by vapor phase reaction of titanium chloride precursors with silicon or boron substrate surfaces are examined. By passing TiCl₄ through a heated chamber packed with titanium metal turnings within the reactor tube, a reduced titanium halide is generated. It was found that the silicide or boride formation in the reactor can thus be controlled at a much lower temperature. Also, excessive silicon erosion normally encountered at the higher operating temperature (>775°C) required for the direct TiCl₄ reaction is minimized. Characterization of the resulting films was conducted by use of scanning and transmission electron microscopy, sheet resistance measurements, and x-ray diffraction.