Applied Physics Express · 2008 · 12 citations · 12 references
EngineeringMaterials EngineeringMaterials ScienceSemiconductor DevicesSemiconductor MaterialsThin FilmsMetal-semiconductor ContactsSemiconductor Device MaterialsSemiconductor InterfacesSemiconductor PhysicsSemiconductor SurfacesSurface PhysicsBarrier MaterialsBias Stress EffectsDielectric BreakdownInfrared Absorption SpectroscopyIon DriftMonolayersSelf-assembled Monolayer FormationTime-dependent Dielectric Breakdown
An excellent barrier effect against Cu ion drift is demonstrated using self-assembled monolayer (SAM) barrier dielectrics in which phosphorous (P) atom is contained. Three kinds of SAMs, such as P-, carbon (C-), and nitrogen (N-) containing SAMs with the identical molecular structure, were wet-chemically formed on a thermal SiO2. The X-ray reflectance and infrared absorption spectroscopy revealed that nearly 1-nm-thick monolayers were successfully formed. The barrier effects of SAMs were investigated by the time-dependent dielectric breakdown measurements of Cu/SAM/SiO2/Si metal–insulator–semiconductor structures under applying a bias-temperature stress. The time-to-breakdown tBD of P-SAM was approximately 10-fold compared to SiO2 without SAM formation. The tBD of C-SAM and N-SAM were, on the other hand, well agreed with that of SiO2, indicating that the barrier effects of C- and N-SAMs are much weaker than that of P-SAM. From these results, we concluded that the existence of P atom in the SAM molecule to form Cu-P complex is the key for the barrier mechanism of the SAM studied in this report.
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