Selective chemical vapor deposition of platinum and palladium directed by monolayers patterned using microcontact printing

High-purity platinum and palladium thin films can be deposited selectively by combining microcontact printing (μCP) and metal-organic chemical vapor deposition (MOCVD). Printed patterns of octadecyl-trichlorosilane thin films are used to direct the selective deposition of the metallic thin films from bis-(hexafluoroacetylacetonato)platinum(II), Pt(hfac)₂, and bis(hexafluoroacetylacetonato)palladium(II), Pd-(hfac)₂, in the presence of hydrogen. This process has been used successfully to fabricate Pt and Pd patterns on substrates such as titanium nitride, indium tin oxide, silicon dioxide, and sapphire. Features with sizes as small as 1.5 μm have been deposited by this combined μCP-MOCVD method. The Pt and Pd films were found to be free of detectable impurities, as measured by X-ray photoelectron and Auger electron spectroscopies. Grain sizes in the deposits can also be varied. We found, for example, that the Pt film growth process yields heavily faceted deposits whose habits depend strongly on the temperature of the substrate during processing. Addition of water vapor to the reactor feed during platinum chemical vapor deposition increased the number of nucleation sites, thus reducing the grain size, but did not otherwise affect the deposition rate to a significant degree. We describe in this report how this photolithography-free process might simplify the patterning of metal and other thin films of interest in integrated circuit fabrication.