Combined experimental and modeling studies of laser-assisted chemical vapor deposition of copper from copper(I)-hexafluoroacetylacetonate trimethylvinylsilane

Abstract

We describe laser-assisted chemical vapor deposition of copper from copper(I)- hexafluoroacetylacetonate trimethylvinylsilane onto silicon and metal substrates. The deposition process was driven thermally with 514.5 nm radiation from an argon ion laser. The relationship between operating parameters and the materials properties of deposited copper lines was investigated experimentally and interpreted through models of the deposition process. The as-deposited Cu lines were of high purity, showing no detectable carbon and oxygen contamination, and at optimal conditions, the resistivity of the lines was comparable to that of bulk copper. The line morphology was strongly dependent upon laser power with volcano shapes appearing at higher powers, as well as spatially periodic structures occurring in a narrow range of laser powers and scanning speeds. A mathematical model was developed for the laser heating and deposition processes to provide insight into the fundamental processes underlying the observed phenomena. Optical and thermophysical property changes caused by the continuously growing deposit were included, thereby enabling accurate predictions of the laser induced temperature distributions. The surface temperature distribution and the maximum temperature rise at the center of the laser beam were significantly affected by the deposit. The model further allowed identification of kinetic parameters for the deposition process. The volcano-shaped deposits were attributed to enhanced desorption of precursors in the center of the irradiated spot, and the periodic structures were interpreted in terms of a nonlinear coupling between heat conduction and chemical kinetics.