| AVS 55th International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS-WeA |
| Session: | Frontiers of Analysis and Combined Materials |
| Presenter: | J. Matsuo, Kyoto University, Japan |
| Authors: | J. Matsuo, Kyoto University, Japan S. Ninomiya, Kyoto University, Japan H. Yamada, Kyoto University, Japan K. Ichiki, Kyoto University, Japan Y. Nakata, Kyoto University, Japan T. Aoki, Kyoto University, Japan T. Seki, Kyoto University, Japan |
| Correspondent: | Click to Email |
Interest in soft materials, such as polymers or biological materials, has increased in the last decade. SIMS analysis and molecular depth profiling of soft materials with polyatomic and cluster ions have been demonstrated recently. The multiple collisions and high-density energy deposition of these ions on solid surfaces induce enhancement of sputtering and secondary ion yields, as well reduced residual surface damage compared with other techniques. We have demonstrated that the sputtering yields of polymer and amino acids with large Ar cluster ions (mean size: 1000) at the energy of 20 keV are more than 100 molecules/ion, and sputtered surfaces are much smoother than the original surfaces. Secondary ions emitted from arginine (Arg, C6H14N4O2), leucine (Leu, C6H13NO2), glycylglycylglycine (GlyGlyGly, C6H11N3O4), polymethyl methacrylate (PMMA), and tris (8-hydroxyquinoline) aluminum (Alq3, C27H18AlN3O3) films were measured using the time-of-flight (TOF) technique under the incidence of large Ar cluster ions at incident energies of 3 and 20 keV. The ratio of fragment ions to molecular ions decreases quite rapidly with increasing cluster size. Very few fragment ions were observed in the mass spectrum, when the cluster size was larger than 1000. The kinetic energy of a few eV/atom is comparable to the bonding energy of molecules. We have found that residual damage is strongly dependent on the incident velocity of cluster ions, when the size of the cluster ion is larger than 100, and this result is well matched with recent MD simulations. Ultra-low energy SIMS and molecular depth profiling of various soft materials can be realized by using large Ar cluster ions. Recently, molecular depth profiling with low energy (<500eV) monomer ions has also been reported for various polymers. However, in order to realize molecular depth profiling the primary monomer ion beam has to be carefully chosen. The atomistic mechanism of energetic large cluster impacts and the prospects of this technique will be discussed in conjunction with the size effect in secondary ion emission and damage cross-section.