| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS+EM+NS+SS-TuA |
| Session: | Plasma Processing of Challenging Materials - II |
| Presenter: | Kazuhiro Karahashi, Osaka University, Japan |
| Authors: | K. Karahashi, Osaka University, Japan T. Ito, Osaka University, Japan H. Li, Osaka University, Japan M. Isobe, Osaka University, Japan K. Mizotani, Osaka University, Japan S. Shigeno, Osaka University, Japan M. Fukasawa, Sony Semiconductor Solutions Corporation, Japan A. Hirata, Sony Semiconductor Solutions Corporation, Japan T. Tatsumi, Sony Semiconductor Solutions Corporation, Japan S. Hamaguch, Osaka University, Japan |
| Correspondent: | Click to Email |
Gases containing hydrogen are widely used in microfabrication processes of electronic devices using plasma etching. For example, HBr gas is used for silicon etching, hydrofluorocarbon gases are used for silicon oxide etching, and Hydrocarbon-based non-corrosive gases are used for transparent conducing oxides etching. Unlike other atoms, hydrogen is lighter in weight, smaller in atomic radius, and chemically reactive, so it has various effects in the etching process. In order to precisely control the etching reaction and realize nanometer order microfabrication processes, it is necessary to clarify the effect of hydrogen. In this study, by comparing various effects on etching processes between hydrogen and helium incident ions using molecular dynamics (MD) simulation and ion beam experiments, physical and chemical effects by such light ion injection on etching processes were evaluated.
We have shown in this study based on MD simulation and ion beam experiments that, when a Si surface exposed to an O radical flux is simultaneously irradiated by an H+ or He+ ion beam, diffusion of oxygen atoms into the Si film is promoted. Since the enhanced diffusion occurs in a similar manner in both cases of H+ and He+ ion injections, it is clear that the enhanced diffusion is essentially caused by knock-on effects by incident light ions. On the other hand, in the case of etching of ZnO, which is an ionic crystal, our beam experiments have shown that its crystal size decreases by light ion irradiation using in-plane X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) measurements. The reduction of grain sizes seems correlated with the reduction of the physical sputtering yield of the ZnO film.
The results above show the following two physical effects by irradiation of a substrate with light ions such as H+ and He+ ;1) enhancement of diffusion of heavy atoms deposited on the substrate surface into it’s the bulk of the film and 2) decrease of grain sized of ionic crystalline substrate due to amorphization and recrystallization. The decrease of grain sizes, which induce the increase in grain boundary areas may contribute to an increase in sputtering yield of the substrate.