Evolution of the 2D surface structure of a silicon pitch grating under argon ion bombardment: Experiment and modeling

This work aims at validation of the newly developed SDTrimSP-2D code by comparing experimental measurements and modeling of the evolution of a 2D surface structure under argon ion bombardment. SDTrimSP-2D allows for the simulation of ion-surface interactions with 2D micro-structured surfaces, where the first dimension is the depth and the second is parallel to the surface. The main advantage of the approach implemented in SDTrimSP-2D is that the interdependency of surface morphology and sputtering is naturally taken into account. The code follows the evolution of surface morphology and provides a detailed nanoscale description of processes characterizing the ion-surface interactions. In this work, a Si pitch grating with typical dimensions of 200–250 nm, provides a well-characterized 2D system. This is bombarded with 6 keV Ar + ions at normal incidence angle as well as at an angle of 42° both parallel and perpendicular to the pitch grating structure. Cross-sections of the bombarded Si pitch grating were obtained by SEM and compared to the calculated surface profile revealing good agreement between experiment and simulation. The calculations also provide improved insight into the mechanisms of grating erosion and material transport by redeposition.