Gas phase studies of new copper(I) carboxylates compounds with vinylsilanes and their application in Chemical Vapor Deposition (CVD) Iwona B. Szyman ´ ska * , Piotr Piszczek, Edward Szłyk Department of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Torun ´, Poland article info Article history: Received 23 October 2008 Accepted 17 December 2008 Available online 9 February 2009 Keywords: Copper(I) Vinylsilane Perfluorinated carboxylates MS Temperature variable IR CVD abstract Copper(I) carboxylate compounds with vinylsilanes of the general formula [Cu(L)(l-O 2 CR)] n , where L = CH 2 @C(H)SiMe 3 , CH 2 @C(H)SiEt 3 , CH 2 @C(H)Si(OMe) 3 ; R = CF 3 ,C 2 F 5 ; n = 2 or 3, have been synthesized and characterized in the solid state and in the gas phase by variable temperature IR spectroscopy, mass spectrometry and thermal analysis. Complexes are di- or trimeric species with bridging carboxylates and dihapto coordinated vinylsilanes. Electron impact mass spectra indicate metallated species in the gas phase, of which the [Cu 2 (O 2 CR)] + and [Cu 2 (O 2 CR) 2 ] + ions revealed the highest intensity. Similar copper(I) carboxylates derivatives [Cu 2 (O 2 CR) 2 ] were detected in the vapors by variable temperature IR spectral analysis, which suggests that these species can be transported in the CVD process. The vaporization tem- perature of the metallated fragments was lower in the case of [Cu(L)(l-O 2 CC 2 F 5 )] n than for the [Cu(L)(l- O 2 CCF 3 )] 2 complexes, therefore [Cu(CH 2 @C(H)SiMe 3 )(l-O 2 CC 2 F 5 )] n and [Cu(CH 2 @C(H)SiEt 3 )(l-O 2 CC 2 F 5 )] n have been selected for CVD experiments. Considering the results of the TGA, MS and variable temperature IR studies, the thermal decomposition pathway and the mechanism of the Cu layers formation are pro- posed. Copper layers were deposited by Chemical Vapor Deposition and characterized by XRD and SEM methods. The morphology of the copper layers depends on the properties of the used substrates: Si(1 1 1), stainless steel, ITO and quartz. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The synthesis and characterization of copper organometallic and coordination compounds as new precursors for Chemical Va- por Deposition (CVD) of metallic nanometric layers is an area of extensive research. Copper is an important material in advanced metallization for microelectronic and optoelectronic devices [1– 4], high-temperature superconducting materials [5], ultra-large scale integrated (ULSI) circuits due to its low electrical resistivity, and higher stress-induced deformation and electromigration resis- tance than aluminum. Fabrication of metal thin films using CVD techniques is a matter of interest, due to advantages such as the kinetically controlled deposition process, the conformal coverage and possibility of the selective deposition. Precursors used in CVD influence the course of the deposition process, morphology, structure and physicochemical properties of the deposited layers [1,6]. Therefore, the synthesis and selection of compounds, which can be applied as precursors in CVD is the scope of the present work. The selection of precursors is based on their volatility, ther- mal decomposition mechanisms and the stability of the metallated species in the gas phase, which should withstand the transport stage in the CVD processes. In the case of Cu(I) precursors, the disproportionation reaction to metallic copper and copper(II) species is advantageous. [Cu(b- diketonate)(L)] (b-diketonate = acetylacetonate (acac), 1,1,1-triflu- oroacetylacetonate (tfac), 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac)), L = tertiary phosphines (e.g. PMe 3 ), vinyltrimethylsilane (VTMS), vinyltrimethoxysilane (VTMOS), 2-methyl-1-hexene-3- yne (MHY), dimethyl-1,5-cyclooctadiene (DMCOD), [Cu(b-diketoi- minate)(L)] [7] and [Cu(g 5 -C 5 H 5 )(L)] [8–10] are applied as CVD precursors [4,11–15]. Moreover, homobinuclear complexes with non-cyclic dienes [Cu 2 (hfac) 2 (L)], where L = 1,5-hexadiene (HD) and 1,3-divinyltetramethyldisiloxane (DVTMSO) can be promising as precursors because they appear to be volatile and thermally sta- ble [16]. Among Cu(I) b-diketonate compounds are volatile liquids, which decompose between 403 and 573 K to metallic copper with a multistep mechanism [6,15]. However, the majority of these complexes are moisture and air sensitive. Among them, commer- cially available, [Cu(hfac)(MHY)] and [Cu(hfac)(VTMS)] are most frequently used as the precursors for CVD of thin copper films [6,17,18]. CVD experiments of the latter compound have resulted in high purity metallic layers when the substrate temperature was in the range 423–463 K [19,20]. Besides its low thermal stabil- ity, during evaporation [Cu(hfac)(VTMS)] partially decomposes, which seems to be the main disadvantage in thermally-induced CVD methods. Therefore, we have focused on searching for new precursors, based on Cu(I) perfluorinated carboxylate complexes 0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2008.12.052 * Corresponding author. Tel.: +48 56 611 4317; fax: +48 56 654 2477. E-mail address: pola@chem.umk.pl (I.B. Szyman ´ ska). Polyhedron 28 (2009) 721–728 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly