Characterization of Ru Thin-Film Conductivity upon Atomic Layer Deposition on H-Passivated Si(111)

The sheet resistance measured by a four-probe technique is compared to the resistivity data derived from the optical response of thin ruthenium films grown on hydrogen-passivated Si(111) surfaces by atomic-layer deposition using cyclopentadienyl ethylruthenium dicarbonyl, Ru(Cp)(CO)2Et and O 2 as gas reactant. The Drude-Landauer theory is applied to evaluate the spectroscopic ellipsometry response and the DC resistivity evaluated by 4-point probe measurements. Results indicate that thin Ru films (below ∼5nm) deposited on Si exhibit a higher sheet resistance than similarly grown Ru films on TiN. This is explained by an island-growth mechanism at the initial stages of Ru deposition that greatly diminishes the film conductivity before the formation of a continuous film. © 2012 American Institute of Physics.