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The mechanism of copper chemical vapor deposition from Cu(II)bis-hexafluoroacetylacetonate [Cu(hfac)2] and 1,5-cyclooctadiene-Cu(I)-hexafluoroacetylacetonate (COD-Cu-hfac) has been determined. The results explain the different processing conditions required for deposition from the precursors. Both molecules react at room temperature on Ag to form a similar Cu(I)-hfac surface intermediate. Subsequent reaction of the COD-Cu-hfac fragment can lead to loss of the organic ligands leaving clean Cu. In contrast, for Cu(hfac)2, the presence of one extra surface hfac requires the addition of an external reductant to produce a ligand-free Cu film.

The equilibrium hydrogen surface coverage on Si(100) during silicon epitaxy using SiH4 has been measured in a rapid thermal chemical vapor deposition reactor. The hydrogen coverage could be ‘‘frozen out’’ completely on the surface by a rapid cool-down and pump-down of the reactor up to temperatures of ≂575 °C; at temperatures above 575 °C only partial ‘‘freeze-out’’ is achieved. Surface hydrogen was titrated in situ using the reactor as a thermal desorption spectrometer. Epitaxial silicon films were grown in the temperature range 450–700 °C and the film growth kinetics was correlated with the equilibrium hydrogen coverage. The growth mechanism changes from the low-temperature regime, where the surface is hydrogen covered, to the high-temperature regime, where the surface is essentially clean.

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