Electroless deposition and electrical resistivity of sub-100 nm Cu films on SAMs: State of the art

Self-assembled organic monolayers (SAMs) of silanes with –SH, –NH2 and –C5H4N functional groups have been shown recently to act as ultra-thin, robust diffusion barriers at the Cu/SiO2 and Cu/ultra low-k dielectric interfaces. More generally, SAMs with their tunable surface chemistry are essential elements of future all-wet ULSI metallization with Cu deposited by electroless (ELD) over SAM-functionalized dielectrics. Far too small is known however on the electrical properties of thin metal films formed onto SAM/dielectric substrates. In this paper, we give first a brief literature survey of what is known about Cu films deposited by electroless over dielectrics modified by SAMs. Second, we present our observations of electrical resistivity ρ of sub-100 nm ELD Cu films deposited over the surface of amino-silane SAM/SiO2 activated by Au monodispersed nano-particles and show that this techniques helps to obtain considerably smaller ρ compared to the previously reported data.