| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS1-ThA |
| Session: | Fundamentals of Plasma-Surface Interactions II |
| Presenter: | H. Tsuda, Kyoto University, Japan |
| Authors: | H. Tsuda, Kyoto University, Japan T. Nagaoka, Kyoto University, Japan K. Eriguchi, Kyoto University, Japan K. Ono, Kyoto University, Japan H. Ohta, University of California, Santa Barbara |
| Correspondent: | Click to Email |
An atomic-scale understanding of interactions between chemically reactive plasmas and surfaces is required to establish nanometer-scale processing technologies. Various numerical studies based on molecular dynamics (MD) simulation have been reported so far, but these were limited to simulations of the simple blanket etching to estimate microscopic etching properties [1,2]. Here, we first report a fully atomistic silicon feature profile simulation using classical MD simulations. The potential form can be found in our previous papers [2,3,4]. F, Cl, and Br beams with a translational energy of 100 eV were used as reactive species. The surface area of Si (100) substrates was about 163 × 22 Å2, where 3840 silicon atoms were initially located in the structure of diamond lattice. M ask patterns were introduced in the direction parallel to the short axis with periodic condition, in order to reproduce the trench etching feature. Then, the area without mask was 50 × 22 Å2. By using our new atomistic profile evolution simulation, we investigated halogen plasma-surface interactions at sidewalls and bottom surfaces of nanometer-scale Si trench in detail. It was found that specific feature profiles with different gaseous species appear not only at the sub-micrometer-scale but also at the nanometer-scale etching, and the difference of surface reaction layer formation strongly affects the feature profile evolution during etching. For instance, fluorine beam etching showed that fluoride layer is formed on the entire surfaces containing sidewalls and bottom surfaces, thus giving isotropic etching. Chloride layer was thicker than fluoride and bromide layers, to give feature profiles of sidewall tapering. Bromide layer on bottom surfaces was thinnest among the three, and so the etching rate was lowest. So, it was cleared that the surface reaction layer formation strongly affects the feature profile evolution during etching. Our approach is essential as a reference for macroscopic or empirical profile simulation, where simulation sizes have been reduced recently. We also show some comparison between MD-based profile simulation and our empirical profile simulation (atomic-scale cellular model [5]).
[1] H. Ohta et al., J. Vac. Sci. Technol. A 19, 2373 (2001).
[2] T. Nagaoka et al., J. Appl. Phys. 105, 023302 (2009).
[3] H. Ohta and S. Hamaguchi, J. Chem. Phys. 115, 6679 (2001).
[4] H. Ohta et al., J. Appl. Phys. 48, 020225 (2009).
[5] Y. Osano and K. Ono, J. Vac. Sci. Technol. B 26, 1425 (2008).