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Electron-beam induced deposition of high-purity copper nanostructures is desirable for nanoscale rapid prototyping, interconnection of chemically synthesized structures, and integrated circuit editing. However, metalorganic, gas-phase precursors for copper introduce high levels of carbon contamination. Here we demonstrate electron beam induced deposition of high-purity copper nanostructures from aqueous solutions of copper sulfate. The addition of sulfuric acid eliminates oxygen contamination from the deposit and produces a deposit with ∼95 at% copper. The addition of sodium dodecyl sulfate (SDS), Triton X-100, or polyethylene glycole (PEG) improves pattern resolution and controls deposit morphology but leads to slightly reduced purity. High resolution nested lines with a 100 nm pitch are obtained from CuSO-HSO-SDS-HO. Higher aspect ratios (∼1:1) with reduced line edge roughness and unintended deposition are obtained from CuSO-HSO-PEG-HO. Evidence for radiation-chemical deposition mechanisms was observed, including deposition efficiency as high as 1.4 primary electrons/Cu atom.

Focused electron beam induced deposition of pure materials from aqueous solutions has been of interest in recent years. However, controlling the liquid film in partial vacuum is challenging. Here we modify the substrate to increase control over the liquid layer in order to conduct a parametric study of copper deposition in an environmental scanning electron microscope. We identified the transition from electron to mass-transport limited deposition as well as two additional regimes characterized by aggregated and high-aspect ratio deposits. We observe a high deposition efficiency of 1–10 copper atoms per primary electron that is consistent with a radiation chemical model of the deposition process.

Abstract-Multipactor effect is studied in a hollow elliptical waveguide carrying two orthogonal polarization modes, i.e., the fundamental (TE c11 ) and the second (TE s11 ) elliptical waveguide modes. The introduction of a modal equivalent voltage allows defining the standard axial ratio, which characterizes each polarization state of the problem. The RF breakdown threshold is determined as a function of the axial ratio, for various amplitudes, and phases of the two elliptical modes. In particular, the effect of second mode on the RF breakdown threshold of the fundamental mode is studied. The simulations are carried out for different values of the ellipse eccentricity.

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