SELECTIVE LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION OF COPPER - EFFECT OF ADDED WATER-VAPOR IN HYDROGEN OR HELIUM CARRIER GAS

The low pressure chemical vapor deposition (LPCVD) of copper from its bis-hexafluoroacetylacetonate is studied on oxidized silicon substrates partially covered with a platinum seeding layer. With a known concentration of water vapor in the gas mixture, almost equal copper film growth rates are obtained when using either hydrogen or helium as carrier gas. For both carrier gases, an increase of the copper growth rate is observed with an increasing amount of water vapor added to the gas mixture, and deposition rates above 500 angstrom/min are obtained. The chemical purity and electrical conductivity of the copper deposit are as high in the case of a helium carrier gas as in the case of a hydrogen carrier gas. Implications for the mechanism of copper LPCVD are discussed.