Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5 -cyclooctadiene)copper(I), (
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K.M. Chi and M.J. Hampden-Smith3) Department of Chemistry and Center for Micro-Engineered Ceramics, University of New Mexico, Albuquerque, New Mexico 87131
T.T. Kodasa> Department of Chemical Engineering, and Center for Micro-Engineered Ceramics, University of New Mexico, Albuquerque, New Mexico 87131
J. D. Farr and M. F. Paffett CLS-1, Los Alamos National Laboratories, Los Alamos, New Mexico 87545 (Received 9 April 1991; accepted 25 September 1991)
Hot- and cold-wall chemical vapor deposition (CVD) using the volatile copper(i) compound (hfac)Cu(l,5-COD), where hfac = 1,1,1,5,5,5,-hexafiuoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that had been patterned with Pt or W, over a temperature range 120 °C-250 °C. Deposition was observed onto Pt, W, and SiO2 over this temperature range at rates of up to 3750 A/min to give copper films that contained no detectable impurities by Auger electron spectroscopy and gave resistivities of 1.9-5.7 /x ohm cm. The volatile by-products formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quantitative disproportionation reaction: 2(hfac)Cu(l,5-COD) — • Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compounds (/3-diketonate)Cu(PMe3) where /3-diketonate = hfac, 1,1,1-trifluoroacetylacetonate (tfac), and acetylacetonate (acac).
Chemical Vapor Deposition (CVD) of copper is an area of much current research interest due to the possibility that copper, as a result of its low resistivity, is a candidate interconnect material in Integrated Circuit (IC) fabrication. In the search for metal-organic copper compounds suitable for CVD of copper, copper(n) (3diketonate1"10 and copper(n) Schiff base11 compounds have been studied. Copper(n) /3-diketonate compounds generally deposit pure copper films in the temperature range 340 °C-390 °C. The presence of a reducing gas such as hydrogen seems to aid deposition of high purity copper films and reduces the deposition temperature to 250 °C. Copper(i) species are being studied and thus far have allowed deposition of pure copper films at temperatures as low as 100 °C, without the need for carrier gas.12""21 Preliminary studies have shown that selective deposition onto metals such as Pt, W, and Cu and onto TiN* can be achieved in the presence of SiO2 _14,19,20
^Authors to whom correspondence should be addressed. J. Mater. Res., Vol. 7, No. 2, Feb 1992 http://journals.cambridge.org
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An additional attractive feature of using copper(i) species as CVD precursors is the possibility that thermally induced disproportionation may occur, leading to the formation of copper metal and volatile copper(n) compounds. Suitable conditions may be found under which the copper(i) reactant disproportionates while the copper(n) product
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