The application of alloy liquid metal ion sources in mass separated focused ion beams

For special purposes like writing ion implantation or ion mixing in the micrometer- or sub-micrometer range different ion species are needed. Therefore alloy liquid metal ion sources (LMISs) are used. The energy distribution of the ions from an alloy LMIS is one of the determining factors for the performance of a FIB column. Different source materials like Au73Ge27, Au82Si18, Au77Ge14Si9, Co36Nd64, Er69Ni31, Ga38Bi62, Mn43Ge57, In50Ga50, Sn86Pb14 and Er70Fe22Ni5Cr3 were investigated with respect to the energy spread of the different ion species as a function of emission current, ion mass, charge state and emitter temperature and the abundance of the species, emitted from the tip, in the mass spectra.
Most of the alloy LMISs discussed above have been used in the Rossendorf FIB system IMSA-Orsay Physics especially for writing implantation to fabricate sub-micrometer pattern without any lithographic steps. A Co-FIB was applied for the ion beam synthesis of CoSi2 micro-and nanostructures. Additionally, the possibility of varying the current density with the FIB by changing the pixel dwell time was used for radiation damage investigations in Si, Ge and SiC at elevated implantation temperatures. Furthermore, a broad spectrum of ions was employed to study the sputtering process depending on temperature, angle of incidence and ion mass on a couple of target materials using the volume-loss method as well as used for patterning of different surface structures, i.e. in nano-functional films. Especially this technique was used for the fabrication of various kinds of micro-tools.