Nucleation of copper on TiW and TiN during chemical vapor deposition

Copper grows as continuous films on various silicides and metals at substrate temperatures of 310–385 °C, total pressures of 2–10 Torr, and precursor vessel temperatures of 60–80 °C (precursor mole fractions of 0.004–0.35) with hydrogen using copper (II) hexafluoroacetylacetonate [Cu(HFA)2] as the precursor. However, on TiW, TiW:N, and TiN substrates, that were previously exposed to air, copper formed only small crystalline aggregates, not continuous films, perhaps because of a thin surface layer of oxide. This conclusion was supported by Auger electron spectroscopy and scanning electron microscopy analyses.