Laser-induced chemical-vapor deposition of copper with a cw CO2 laser

The kinetics of the thermal deposition of copper film by decomposing bis-(pivaloyl- trifluoroacetonate) copper(II) [Cu(pta)2] is reported. A cw CO2 laser is used to heat a quartz substrate, on which chemical-vapor deposition of copper takes place. The deposition rate is measured in situ by monitoring the transmittance of the copper film with a He-Ne laser. The deposition rates are determined as a function of CO2 laser intensity and a threshold of 7.9 W has been obtained. Above the threshold the deposition rate increases with laser intensity in the low-intensity region and becomes constant in the high-intensity region. Surface reaction is likely the rate-controlling step of the deposition process at low laser intensity, while diffusion of gaseous precursor molecules to the surface plays an important role at high intensity. Resistivity and thickness of the copper film have also been measured.