| AVS 55th International Symposium & Exhibition | |
| Biological, Organic, and Soft Materials Focus Topic | Tuesday Sessions |
| Session BO+PS+AS+BI+SS-TuA |
| Session: | Plasma-deposited Polymer and Organic Surfaces in Biological Applications |
| Presenter: | A.E. Wendt, University of Wisconsin-Madison |
| Authors: | A.E. Wendt, University of Wisconsin-Madison Y.H. Ting, University of Wisconsin-Madison C.C. Liu, University of Wisconsin-Madison X. Liu, University of Wisconsin-Madison H.Q. Jiang, University of Wisconsin-Madison F.J. Himpsel, University of Wisconsin-Madison P.F. Nealey, University of Wisconsin, Madison |
| Correspondent: | Click to Email |
Diblock copolymers films, in which polymer components segregate into nano-scale domains, have been shown to have tremendous potential in fabrication of nm-scale surface topographies. Applications range from microelectronics fabrication to the study of how topography affects the growth and behavior of living cells or microorganisms. Use of block copolymers as a template for pattern transfer requires selective removal of one polymer component, and has motivated our study of plasma etching of polystyrene (PS) and polymethyl-methacrylate (PMMA), the two components of the PS-PMMA diblock copolymer. To better understand the mechanisms of the etch process for these materials, we have surveyed the effects of etch gas mixture and ion bombardment energy (taking advantage of our capability to produce a narrow ion energy distribution at the substrate), in combination with chemical analysis of the resulting etched surfaces. Of particular interest are the mechanisms of surface roughening, which shows a complex dependence on plasma process conditions that is not easily explained. A review of the literature on factors contributing to surface roughness, such as intrinsic inhomogeneity in the film, local deposition/micro-masking, shadowing effects and redeposition will be presented. We ultimately propose a mechanism for roughening of PS that involves micro-masking by inhomogeneous modification of surface chemical composition (rather than deposition) in oxygen-containing plasmas. Support from the UW NSF MRSEC for Nanostructured Materials is gratefully acknowledged.