title: Direct electroplating of copper on tantalum from ionic liquids in high vacuum: origin of the tantalum oxide layer.
abstract: In this paper, it is shown that high vacuum conditions are not sufficient to completely remove water and oxygen from the ionic liquid 1-ethyl-3-methylimidazolium chloride. Complete removal of water demands heating above 150 °C under reduced pressure, as proven by Nuclear Reaction Analysis (NRA). Dissolved oxygen gas can only be removed by the use of an oxygen scavenger such as hydroquinone, despite the fact that calculations show that oxygen should be removed completely by the applied vacuum conditions. After applying a strict drying procedure and scavenging of molecular oxygen, it was possible to deposit copper directly on tantalum without the presence of an intervening oxide layer.
authors.affiliation: KU Leuven-University of Leuven, Department of Metallurgy and Materials Engineering, Leuven, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: Schaltin
authors.forename: Lucia
authors.initials: L
authors.lastname: D'Urzo
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: André
authors.initials: A
authors.lastname: Vantomme
authors.forename: Harald
authors.initials: H
authors.lastname: Plank
authors.forename: Gerald
authors.initials: G
authors.lastname: Kothleitner
authors.forename: Christian
authors.initials: C
authors.lastname: Gspan
authors.forename: Koen
authors.initials: K
authors.lastname: Binnemans
authors.forename: Jan
authors.initials: J
authors.lastname: Fransaer
mesh_terms: D003300:Copper / Q000737:chemistry*; D004595:Electroplating; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D010087:Oxides / Q000737:chemistry*; D013499:Surface Properties; D013635:Tantalum / Q000737:chemistry*; D014618:Vacuum
chemical_list: D052578:Ionic Liquids; D010087:Oxides; D013635:Tantalum; D003300:Copper; C078151:tantalum oxide