Reduced sulfur-terminated silanes to promote the interaction of palladium(II) hexafluoroacetylacetonate with dielectric surfaces

A simple method is proposed here to modify dielectric surfaces using self-assembled chemistry to improve the interaction with highly polarizable metallorganics. In particular, the study here investigates the interaction between palladium(II) hexafluoroacetylacetonate with sulfur-terminated SiO2 surfaces. Results show that the palladium metallorganic exhibits little if no interaction with a hydroxylated SiO2 surface at a substrate temperature of 175 °C. However, when the SiO2 surface is functionalized with 3-mercaptopropyltrimethoxysilane or bis[3-(triethoxysilyl)propyl]-tetrasulfide silanes via self-assembled chemistry, then favorable interaction is evident with PdII(hfac)2. The surface coverage of PdII(hfac)2 at the modified dielectric surface is proportional to the Pd 3d/Si 2p ratio obtained by the XPS spectra. The largest Pd 3d/Si 2p ratios were obtained when the mercapto-silane was allowed to grow multilayers at the SiO2 surface. Further, elemental chemical vapor deposition experiments also showed little if no growth on the hydroxylated SiO2 surface; but proportional growth on the reduced sulfur-terminated silanes. In all cases, significant fluorine contamination was evident at the dielectric surface after Pd CVD even in the case where no interaction between PdII(hfac)2 and the hydroxylated SiO2 surface took place.