Electrochemical Growth of Cu(Ru) Films via Underpotential Deposition of Pb, Surface-Limited Redox Replacement of Cu, and Underpotential Deposition of Ru

摘要

Copper alloy films can be potentially used as an interconnect material in microelectronics when the feature sizes of the device are reduced. This work investigated Cu and Cu(Ru) films, which were deposited using sequential underpotential deposition of Pb, surface-limited redox replacement of Cu, and underpotential deposition of Ru in an electrochemical manner. Cu film can be formed using the repetitive sequences of an underpotentially deposited Pb sacrificial atomic layer and surface-limited redox replacement of Cu. By adding another underpotentially deposited Ru after the surface-limited redox replacement of Cu, Cu(Ru) films can be successfully deposited by varying the deposition cycle ratios of the surface-limited redox replacement of Cu and the underpotential deposition of Ru. The results showed that the lowest electrical resistivity of 5.2 mu Omega cm was obtained for the Cu(Ru) film deposited at the Cu/Ru cycle ratio of 2/1. The structure and properties of the films were investigated to elucidate their applicability as Cu interconnects for microelectronics.