Atomic layer deposition (ALD) is a process for depositing highly uniform and conformal thin films by alternating exposures of a surface to vapours of two chemical reactants. ALD processes have been successfully demonstrated for many compounds but for very few pure metals. Here, we present a quantum mechanical study of reactions underlying the ALD of copper (transition metal). Copper has caught the attention these days to replace aluminium in electronic interconnect because of its good conductivity and superior resistance to electro migration.  But a complete thin layer is very difficult to get because of its high tendency to agglomerate. A new ALD process for Cu has been developed by Lee et al.[1] based on the following transmetallation reaction:Cu(dmap)2 +  Et2Zn � Cu0 +   Zn(dmap)2  +  C4H10  .................(1)The applicability of transmetallation ALD has been extended to other ligands and co-reagents [2].  A solution phase study revealed [3] the possible mechanism and reaction intermediates. We are studying theoretically how the transmetallation mechanism works via quantum chemical calculations using the TURBOMOLE package [4] using DFT as a key tool.  The mechanism in the solution phase [2][3] as well as during the ALD process [1] is as yet unknown. We examine both the intrinsic reactivity of the transmetallation precursors (gas-phase model) and explicitly model how they react with a copper metal surface (cluster model of surface), using both geometry optimisation and molecular dynamics at the DFT level.  These new ideas about the reaction mechanism pave the way for designing better Cu precursors.References:- Low-Temperature Atomic Layer Deposition of Copper Metal Thin Films, Byoung H. Lee, Roland A. et al,Edition Volume 48, Issue 25, pages 4536�4539, June 8, 2009 Investigation of AlMe3, BEt3, and ZnEt2 as Co-Reagents for Low-Temperature Copper Metal ALD/Pulsed-CVD, Balamurugan Vidjayacoumar, David J. H. Emslie,et al, Chem. Mater., 2010, 22 (17), pp 4844�4853 Solution Reactions of a Bis(pyrrolylaldiminate)copper(II) Complex with Peralkyl Zinc,:, Balamurugan Vidjayacoumar, David J. H. Emslie,  Chem. Mater., 2010, 22 (17), pp 4854�4866

How is transmetallation reaction mechanism helpful for Cu deposition in nanometer scale?

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.