Atomic force microscope study of crater formation in ion bombarded polymer

Polyimide Kapton films with a thickness of 62 μm were bombarded by Ar+, N+, He+ and D+ ions at energies from 10–50 keV. After bombardment at room temperature, the surface topographic changes of the polymer were investigated using an atomic force microscope (AFM). The most common feature of the ion-bombarded Kapton surface is the formation of craters which often have circular shape and rims. The crater sizes suggest they are unlikely to have been caused by a single ion but by the collective effects including diffusion and trapping of gas atoms and gas molecules in ion-bombarded polymer. A model for the formation of these craters is proposed.