Comparative Study of Cu-Precursors for 3D Focused Electron Beam Induced Deposition

Abstract

The copper precursors bis-hexafluoroacetylacetonato-copper Cuhfac) 2 , vinyl-trimethyl-silane-copperI hexafluoroacetylacetonate hfacCuVTMS, 2-methyl-1-hexen-3-yne-copper hexafluoroacetylacetonate hfacCuMHY, and dimethylbutenecopperI hexafluoroacetylacetonate hfacCuDMB 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 hfacCuDMB to about 4 nm/s for Cuhfac) 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 hfacCuDMB and hfacCuVTMS as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented.