| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS1-ThA |
| Session: | Plasma Modeling |
| Presenter: | Y. Morita, Osaka University, Japan |
| Authors: | Y. Morita, Osaka University, Japan M. Isobe, Osaka University, Japan S. Hamaguchi, Osaka University, Japan |
| Correspondent: | Click to Email |
Beam-surface interaction between fluorocarbon ions (mainly CF3+) or hydrogen ions (H+) with a polymethyl methacrylate (PMMA) surface has been examined at the atomic level with the use of molecular dynamics (MD) numerical simulations. The work is motivated by the desire to control line edge roughness (LER) or line width roughness (LWR) observed after plasma etching processes, which is incurred by deterioration of photoresist polymers exposed to reactive plasmas. Molecular structures of commercially available photoresist polymers are complex in general and typically not disclosed in the public domain, so we use PMMA in this work as a model polymer in a hope that, combining this study with other previous studies on plasma-polymer interaction based on other simple organic polymers, an insight into the mechanism of photoresist deterioration due to plasma exposure will be gained. For example, PMMA contains ester bonds (R-COO-R’) and their interactions with plasmas are a subject of this study. In this presentation, we shall focus on two specific issues. One is to evaluate sputtering yields of PMMA by Ar+ or CF3+ ion injections with various injection energies. With Ar+ injection simulations, we shall clarify the nature of physical sputtering of PMMA whereas, with CF3+ injection simulations, we hope to understand the modification mechanism of a polymer mask during oxide etching processes. Our MD simulation results have so far indicated that there is a strong dependence of sputtering yields on the direction of polymer chains against the incoming beam angle at the atomic level. The other issue is solidification of polymer by hydrogen plasma exposure, which may be used to cure polymers after the mask formation process by photolithography. In the simulations, hydrogen beams are injected into PMMA and we have observed increase of the relative carbon density in the polymer due to hydrogen abstraction reactions.