Copper wetting of a tetrasulfide self-assembled monolayer

The adhesion and structure of thin metal films has become increasingly important due to advancements in integrated device technology. The possibility that the adhesion and structure of these metals, such as copper, is intimately related to wetting phenomena has become a focus. The results presented here show that monolayer wetting is evident for copper thermally deposited on a tetrasulfide self-assembled monolayer via Auger electron spectroscopy measurements. In contrast, 3-D island growth is observed on a hydroxylated SiO2 surface. It is the favorable bond energy between the reduced sulfur containing surface and copper that may allow this wetting to occur. Further, the tetrasulfide self-assembled monolayer is particularly robust toward oxidation because it already exists as a tetrasulfide chemical moiety (-SSSS-), as opposed to the mercaptan moiety (-SH). Most important, because the dielectric or barrier surface can be sulfur passivated both via wet or dry chemistry, the findings can be applicable to many material surfaces. (C) 2002 The Electrochemical Society.