SELECTIVE-AREA CHEMICAL-VAPOR-DEPOSITION OF ALUMINUM USING DIMETHYLETHYLAMINE ALANE

Dimethylethylamine alane (DMEAA) was used to deposit Al films selectively on a variety of metal surfaces (Au, Ti, NiCr, W) in the presence of SiO2, Si, and Si3N4. Selectivity ((gs)S(ns)) was quantified as (theta(gs) - theta(ns))/(theta(gs) + theta(ns)) where theta(gs) and theta(ns) represent the coverage of the growth and non-growth surfaces, respectively. At 100-degrees-C, Al films were deposited on 3-mum-wide Au strips in the presence of SiO2 With excellent selectivity ((Au)S(SiO2) > 0.99). Extended deposition times or increased substrate temperatures led to a reduction in selectivity. At 180-degrees-C selectivity dropped to zero. Removing the carrier gas (H-2) and decreasing the DMEAA partial pressure in the system had no significant effect. Encroachment, in which Al at the edges of the Au regions grew laterally onto adjacent SiO2 strips, was observed and had a significant impact on the selectivity of a deposition. Even after very short DMEAA exposure times, trace amounts of Al were detected on silicon oxide surfaces using X-ray photoelectron spectroscopy. Pretreatment of the non-growth surface with hexamethyldisilazane, which converted surface OH groups on SiO2 to trimethylsilyl ethers, did not enhance selectivity.