Surface topography development on ion-beam-sputtered surfaces: Role of surface inhomogeneity induced by ion-beam bombardment

Abstract

To understand the deterioration of the interface resolution in sputter depth profiling and the surface roughness development in semiconductor and thin-film processings, the chemical states of constituents of ion-bombarded surfaces were analyzed by in situ x-ray photoelectron spectroscopy (XPS) measurement under various ion-beam bombardment conditions. The XPS results were compared with secondary-ion-mass spectrometry (SIMS) depth profiling results and surface topographic developments observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) for a Cr/Ni multilayered thin-film structure and a GaAs/AlAs superlattice under various incidence angles and the primary ion species. SEM and AFM measurements showed that the deterioration of the interface resolution was determined mainly by surface topographic development which is very sensitive to the ion incidence angle and the primary ion species. With changing the incidence angle from the surface normal to 80° and the primary ion species between Ar+ and O+2 systematically, the effects of the ion incidence angle and the ion species on the chemical states of constituents, the depth resolution in SIMS depth profiling, and the surface topographic developments were studied by in situ XPS, SIMS, SEM, and AFM, respectively. From the systematic studies on ion-beam-bombarded surfaces of Ni, Cr, GaAs, AlAs, Si, and SrTiO3 under various ion bombardment conditions, it could be concluded that the surface inhomogeneity introduced by ion-beam bombardment is one of the most important factors that determine the surface topographic development on ion-bombarded surfaces.