Metal–dielectric interface toughening by molecular nanolayer decomposition

Recent work has shown that copper–silica interfaces can be toughened several fold by combining interface functionalization with an organosilane molecular nanolayer (MNL) and thermal annealing. In order to understand the role of annealing-induced MNL instabilities on interface toughness, we studied the effects of interface chemical changes on the fracture toughness of copper–silica interfaces tailored with organosilane or organogermane MNLs. Our results indicate that MNL decomposition into its inorganic constituents and consequent intermixing can provide an interface toughening mechanism. Organogermane–tailored interfaces exhibit higher toughness values due to Ge-diffusion induced copper silicate formation, not observed at organosilane tailored interfaces. These findings show that organic nanolayer decomposition at a buried interface could be exploited to tailor interfacial properties through appropriate choice of MNL chemistry and processing treatments.