We report on direct writing of three-dimensional freestanding nanostructures of Cu by use of a focused electron beam (FEB) and the metalorganic precursor hfac-Cu-TMVS. Freestanding horizontal rods were deposited over about 10 μm length and consist of small 2–5 nm Cu nanocrystals dispersed in an amorphous matrix containing carbon, fluorine, silicon, and oxygen. The freestanding horizontal rods were used as support for further vertical deposits resulting in tips of coalesced facetted Cu nanocrystals of up to 100 nm in size. The almost constant deposition rate of 5–6 nm/s is in contrast to vertical tips on bulk supports, which show a deposition rate decreasing from 23 to 10 nm/s. The above results suggest a thermal decomposition process induced by electron energy absorption.

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ABSTRACT:In order to describe the different events occurring during the anionic polymerization of polyamide 12 (PA12), a general concept of a time, temperature, and transformation (TTT) diagram was established and related to reactive processing conditions. Polymerization kinetics were established, and it was found that the reaction was best described by an autocatalytic expression. Polymerization temperatures above and below the final polymer melting temperature were considered. Furthermore, the variation of the melting temperature and viscosity were followed as a function of the polymerization time and degree of conversion. It was shown that monomer-polymer phase separation and crystallization may occur during PA12 polymerization. The results could be adapted for use during liquid molding of PA12 polymers and their composites.

hexafluoroacetylacetonate ͑hfac͒Cu͑MHY͒, and dimethylbutenecopper͑I͒ hexafluoroacetylacetonate ͑hfac͒Cu͑DMB͒ 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 ͑hfac͒Cu͑DMB͒ to about 4 nm/s for Cu͑hfac) 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 ͑hfac͒Cu͑DMB͒ and ͑hfac͒Cu͑VTMS͒ as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented.