Focused-electron-beam-induced deposition of freestanding three-dimensional nanostructures of pure coalesced copper crystals

Abstract

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.