In Situ Monitoring of Selective Copper Deposition Processes in a Metal-Organic Chemical Vapor Deposition Using Fourier-Transform Infrared Reflection-Absorption Spectroscopy

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Abstract
Selective copper deposition processes on titanium nitride (TiN) substrates were investigated by in situ Fourier-transform infrared reflection-absorption spectroscopy and ex situ X-ray photoelectron spectroscopy. Bis-hexafluoroacetylacetonato-copper ( Cu(HFA)2) was used as a source material in a mixture with hydrogen gas. Continuous copper deposition did not occur when the native oxide on the TiN substrates was removed, because the substrate surface was fluorinated by CF2H groups and F atoms which came out from the decomposed CF3 groups in the HFA ligands. On the other hand, thin copper films deposited continuously when the native oxide was present on the TiN substrates. In addition, the copper deposition did not occur on the thermally oxidized silicon ( SiO2) substrates. From these results, it became clear that the selective copper deposition was governed by the conductivity of the substrate, and the presence of the unstable oxygen atoms on the surface, which were produced by the reduction of the unsteady oxide with hydrogen, promoted the film growth.

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