Ion-Beam Induced Surface Roughening of Poly-(methyl methacrylate) (PMMA) Tuned by a Mixture of Ar and O2 Ions

Abstract

The evolution of ion-beam induced surface roughening of PMMA was investigated using an anode-layer ion beam source with O2, Ar, and their mixture. Use of the O2 ion beam created rough granular patterns on the surface of PMMA because O2 ions could break the C?C backbone and subsequently combine with the broken C bonds, resulting in local cross-linking and aggregation. However, the Ar ion beam tended to reduce the surface roughness due to the decomposition of the oxygen-containing ester groups (O?CH3 and O?C?O) and the increase of an overall cross-linking of the amorphous carbon layer, which played a role in etch resistance and suppression of polymer mobility as well as aggregation on the modified PMMA surface. By varying the ratio of Ar over O2, the surface morphology of PMMA was modified to exhibit features ranging from granular roughness to crater-like features.