Morphology and Deposition Conditions of CVD Au Films

Abstract

ABSTRACTThe chemical vapor deposition of Au films by thermal decomposition from an organometallic precursor [dimethyl 1,1,1,5,5,5-hexaflouro-2,3-pentanedionato Au (III)] has been investigated for application as a interconnection metallization. The morphology and feature fill properties of deposits obtained using H2 and N2 carrier gases and varying pressure and temperature conditions were observed by cross-section scanning and transmission electron microscopy (SEM and TEM). Line patterns etched in SiO2 with aspect ratios up to 1.5 filled with few or no voids at a growth temperature of 250°C. For films deposited in H2 the Au grain size is large (on the order of the feature size). In unetched areas, however, large (600 nm) triangular-shaped structures protrude from the deposit. TEM observation shows that these structures are single-crystal Au dendrites which contain a central twinned region. Au films grown at 275°C had poor hole fills with large, irregular voids. These films exhibited large protrusions which occluded the lines and halted growth in these areas. The deposit morphology suggests a low reaction probability except at preferred crystal sites.