Ion cluster emission and deposition from liquid gold ion sources

The emission and deposition of molten gold droplets from needle-tip liquid metal ion sources was investigated. The Taylor cone was identified as the source of droplet emission. An upper limit of 8 μm for the virtual source size was measured. Gold films were deposited on silicon substrates. The deposited gold spots showed a peaked, axially symmetric, distribution with a half angle for droplet emission of ∼2° which was considerably smaller than the ion emission angle of ∼45°. Typical deposition fluxes were ∼5×10⁵ μm³/s/sr with total deposition rates of ∼3×10³ μm³/s and on an average droplet diameter of ∼1 μm at an emission current of 150 μA. Smaller diameter droplets are produced with decreasing emission current and angle. Gold films with a fine textured morphology suitable for submicron patterning were obtained at emission currents less than ∼135 μA.