Comparative study of Cu-precursors for 3D focused electron beam induced deposition

The copper precursors bis-hexafluoroacetylacetonato-copper Cu(hfac)(2), vinyl-trimethyl-silane-copper(I) hexafluoroacetylacetonate (hfac)Cu(VTMS), 2-methyl-1-hexen-3-yne-copper hexafluoroacetylacetonate (hfac)Cu(MHY), and dimethylbutenecopper(I) hexafluoroacetylacetonate (fac)Cu(DMB) are compared with respect to deposition rates and metal content obtained by focused electron beam induced deposition. Exposure was performed with 25 keV electrons in a Cambridge S100 scanning electron microscope equipped with a lithography system. Tip deposition rates increase with increasing precursor vapor pressure and range between 47 nm/s for (hfac)Cu(DMB) to about 4 nm/s for Cu(hfac)(2). A decay of deposition rates with time, i.e., tip length, is observed. Electric four-point measurements indicate an insulating behavior of deposited lines for all precursors. In contrast, Cu contents of up to 45-60 atom % were found by Auger electron spectroscopy in thin rectangular deposits using (hfac)Cu(DMB) and (hfac)Cu(VTMS) as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented. (C) 2004 The Electrochemical Society.