LOW-PRESSURE CHEMICALLY VAPOR-DEPOSITED COPPER-FILMS FOR ADVANCED DEVICE METALLIZATION

This paper describes systematic experiments on the characteristics of copper films prepared by chemical vapor deposition from measured gas-phase concentrations of copper(II) hexafluoroacetylacetonate, Cu(HFA)2, in a cold-wall-type vertical flow reactor with pure hydrogen or a mixture of hydrogen (75%)/argon (25%). The films were analyzed by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), x-ray diffraction (XRD), and spectrophotometry. Under the conditions investigated, film growth rates were 100-1000 angstrom/min depending on processing conditions. The films deposited at 310-390-degrees-C were pure, and the resistivity of the films was routinely near 2.0 muOMEGA em when film thickness was 5000 angstrom or more. The surface roughness of the films increased and their reflectance decreased with increasing film thickness. However, copper deposits having higher reflectance were observed at higher concentrations of precursor in the vapor at a given thickness. Grain sizes were about 0.1 to 2. 0 mum and are correlated with film thickness.