Toward a unified reaction mechanism for chemical vapor deposition of copper

Document Type

Article

Publication Date

1-1-1998

Abstract

We report the reaction kinetics of copper chemical vapor deposition using H2 reduction of Cu(hfac)2 H(hfac) = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione]. We observe a growth rate of 0.48 ± 0.07 mg cm-2 h-1 (i.e., 9 nm min-1) at reference conditions of 300°C substrate temperature, 40 Torr H2 partial pressure, and 1.8 Torr Cu(hfac)2. The dependence of growth rate on operating conditions can be described using a Langmuir-Hinshelwood rate expression with a numerator that is first-order in Cu(hfac)2 and half-order in H2, and a third-order denominator that includes adsorption terms for Cu(hfac)2, H2, and H(hfac). Optimized values for the surface reaction rate constant and the reactant adsorption coefficients are determined using nonlinear regression. On the basis of the optimized rate expression, we propose a minimum-parameter reaction mechanism for Cu(hfac)2 reduction. The proposed rate limiting step is the surface reaction between adsorbed H and the first dissociated (hfac) ligand from adsorbed Cu(hfac)2, leading to the desorption of H(hfac) product. The proposed mechanism also includes the major elementary steps needed to describe the competing disproportionation reaction. In particular, the rate constant for recombinative desorption of Cu(hfac)2 obtained in the present work is remarkably consistent with previous kinetic results for Cu(hfac)(2-butyne) disproportionation.

Publication Source (Journal or Book title)

Journal of the Electrochemical Society

First Page

347

Last Page

352

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