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

Wei Dai, Tae-Jun Ko, Kyu Hwan Oh, Kwang-Ryeol Lee and Myoung-Woon Moon
 

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.