Focused ion‐beam direct deposition of metal thin film

Focused ion‐beam direct deposition has been developed as a new method for fabricating patterned metal films directly on substrates. The principle of this method is to perform ion‐beam deposition by low‐energy focused ion beams. We designed and constructed a low‐energy focused ion‐beam apparatus for direct deposition. Metal ions are extracted from liquid metal ion source, accelerated to 20 keV for single charged ions, focused, mass separated, deflected, and finally, decelerated to 30–1000 eV in this system. The beam diameter estimated by the deposited linewidth can be tuned between 0.5 and 8 μm and the beam current varies from 40 pA to 10 nA corresponding to the beam diameter for the Au+ ion in the energy range from 30 to 200 eV. The sticking probabilities of ion‐beam deposition were measured and the critical energies for Au+, Cu+, Al+, and Nb2+ were about 210, 230, 800, and 1300 eV, respectively. The purity of gold film was measured by Auger electron spectroscopy and secondary‐ion‐mass spectroscopy. The c...