Molecular dynamics simulation study of damage formation and sputtering with huge fluorine cluster impact on silicon

Damage formation and sputtering processes by large reactive cluster impact on solid target were studied by molecular dynamics (MD) simulation. A (F2)500,000 cluster was accelerated at 1 MeV (1 eV/atom, 3.2 km/s) and projected toward a Si(100) target which consisted of more than 130,000,000 atoms. The MD simulation result showed that wide and shallow crater is formed due to the impingement of the bottom part of the incident cluster. The target atoms in a large area surrounding the impact point were largely displaced and some of them remained as a point defect or as a stacking fault, which reached more than 10 nm deep into the target surface. By the single impact of the cluster, about 12,000 silicon atoms were desorbed into the vacuum. The desorbed products were in the form of not only mono-silicon fluoride but also in larger silicon-fluoride composite clusters. The distribution of initial position of desorbed silicon atoms showed that most of desorbed products were generated in the region close to the crater edge corresponding to the radius of incident cluster.