Direct-on-barrier copper electroplating on ruthenium from the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide
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The "direct-on-barrier" electroplating of copper on ruthenium from a 1 mol dm−3 solution of CuCl in the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide, [C2mim][N(CN)2], is reported. Continuous layers of copper with a preferential Cu(111) orientation were obtained from this electrolyte. The copper coatings were investigated by top view scanning electron microscopy (SEM), X-ray diffraction (XRD), and focused ion beam transmission electron microscopy (FIB-TEM). The nucleation density was both theoretically and experimentally evaluated by the Scharifker-Hills model and transmission electron microscopy, respectively. The direct plating of copper on resistive substrates for advanced interconnects and package is a promising new application of ionic liquids.
KeywordsIonic Liquid Ruthenium Atomic Layer Deposition Nucleation Density Ruthenium Oxide
Our grateful thanks to Werner Robl and and Raimund Foerg from Infineon Technology for providing the silicon wafers used in this study. We thank Danny Winant for his assistance with TGA measurements. Research funded by a Ph.D grant of the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen) to S.S. This work is supported in part by the European Commission‘s Seventh Framework Programme (FP7) under Grant Agreement number 216474 (CopPeR). The authors acknowledge financial support by the K. U. Leuven (projects IDO/05/005 and GOA 08/05), by the FWO-Flanders (research community "Ionic Liquids"), by the IWT-Flanders (SBO-project IWT 80031 "MAPIL") and the support of the Belgian Federal Science Policy Office through the IUAP project INANOMAT (contract P6/17). Support by IoLiTec (Heilbronn, Germany) is also acknowledged.
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