Molecular dynamics study of the angular dependence of reactive cluster impacts

摘要

The collisional processes of fluorine clusters impacting at various incident angles on bare silicon surfaces were studied, and the change of the surface profile, sticking probabilities of F atoms, sputtering yield and the distribution of the sputtered particles were examined. When a (F_2)_(300) cluster with 10 eV/atom impacts on a Si(100) surface at normal incident, the cluster penetrates the surface causing a spherical crater structure with the F atoms densely covered. As the incident angle increases, the penetration depth of cluster decreases and the simulation shows an asymmetric crater profile. Especially at an incident angle of 75°, the surface profile did not change but F atoms were deposited over a wide area. The distribution of sputtered particles also depends on incident angle. At normal incidence, the Si atoms are sputtered as well as silicon-fluoride molecules such as SiF and SiF_2, while only SiF_x molecules are sputtered at 75° of incident angle. From these results the surface etching process caused by reactive cluster impacts are discussed.