Modeling of a multicharged ion beam line using SIMION

Abstract

Multicharged ion beams (MCI) are promising tools to probe or modify the surface of materials with applications in microelectronics and nanotechnology. Ion beam lines are parts of the MCI systems connecting the ion source with the processing chamber and they perform the function of extracting, accelerating, decelerating, focusing and scanning the ion beam on the surface of the target. In our work we present results of modeling of an MCI beam line using the SIMION code to simulate the flight of ions, with the purpose of optimizing the yield of the line and avoiding spurious effects due to interaction of the ions with the metallic elements of the line, such as heating, outgassing and excessive Xray emission. We show that a two stage ion extractor could significantly reduce ion beam losses.Keywords: multicharged ions, heavily charged ions, ion beam, ion optics, computer-aided modeling INTRODUCTIONIon implantation is one of the key processes in modern microelectronic fabrication. Ions in the form of focused beams or plasma are also present in various etching processes used in microelectronic and semiconductor technology. Those processes utilize singly charged ions, with energies typically from 0.2 keV (for shallow junction implantation) to about 2 MeV (for multiple-well doping). The kinetic projectile energy of the ions is of great importance.Recently, a new tool for material processing has attracted the attention of researchers and process engineers: the multicharged ion (MCI) beam. A vast literature is devoted to the subject of MCI. Some review articles and books devoted to them [1-5] as well as recent journal papers on MCI physics and technology are included in the bibliography. The following brief and not exhausting overview is based on those publications. The ion charges for material processing are typically in the range from q +2 to q +18 . For atomic science studies highly charged ions (HCI) have been produced up to "naked" atoms -i.e. atoms completely stripped of electrons. U 91+ uranium was obtained using a 198 kV electron beam at the Lawrence Livermore Super-EBIS. The new class of ion-surface interactions depends on the internal energy of the projectiles, i.e. its potential energy added by stripping the electron from the atom while forming the ion, especially if the potential energy exceeds significantly the ion kinetic energy, which in certain circumstances could be by several orders of magnitude. That makes possible either delivering high energies to the interaction site using kinetic energies reduced by the factor of ionization or reducing the acceleration voltage of the ions and conducting the surface processes at very low energies -down to a few eV with ultra slow multicharged ions (USMCI). The control of the ion energy and dose can be in MCI systems much more precise than in common plasma processes. The interaction of MCI with solids shows some specific differences from that of single-charged ions. Some previously unknown effects, like existence of naked and hollow atoms (completely ionized atoms and ...

Friction and wear properties modification of Ti–6Al–4V alloy surfaces by implantation of multi-charged carbon ions

“…The micro massspectrometer keeps the carbon multi-charged beams together in close trajectories and, separates those beams from the intense hydrogen mono-charged "pollutant" beam. The magnetic structure of the device was designed with RADIA [17] and the ion trajectories were calculated by SIMION 3D and CPO 3D [18][19][20]. The spatial separation between the hydrogen beam and the carbon beams is in the order of several centimeters.…”