| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Friday Sessions |
| Session PS-FrM |
| Session: | Plasma Modeling |
| Presenter: | Hirotaka Tsuda, Kyoto University, Japan |
| Authors: | H. Tsuda, Kyoto University, Japan Y. Takao, Kyoto University, Japan K. Eriguchi, Kyoto University, Japan K. Ono, Kyoto University, Japan |
| Correspondent: | Click to Email |
Three-dimensional measurement and prediction of atomic-scale surface roughness on etched features become increasingly important for the fabrication of next-generation devices; however, the feature profiles are too small or too complex to measure the surface roughness on bottom surfaces and sidewalls of the etched features. To predict the surface roughness on atomic or nanometer-scale, we have developed our own three-dimensional atomic-scale cellular model (ASCeM-3D) [1] and feature profile simulation. Emphasis is placed on a better understanding of the formation mechanisms of atomic-scale surface roughness during Si etching in chlorine-based plasmas and the relationship between the ion incident energy and angle and etched feature profiles.
In the ASCeM-3D model, the simulation domain is divided into a number of small cubic cells of L = rSi-1/3 = 2.7 Å, where rSi = 5.0 x 1022 cm-3 is the atomic density of Si substrates. Ions and neutrals are injected from the top of the simulation domain, and etch and/or sputter products are taken to be desorbed from etching surfaces into microstructural features, where two-body elastic collision processes between incident ions and substrate atoms are also taken into account to analyze ion reflection on etched feature surfaces and penetration into substrates. The ASCeM-3D takes into account surface chemistries based on the Monte Carlo (MC) algorithm [2-4], including adsorption and reemission of neutrals, chemical etching, ion-enhanced etching, physical sputtering, and redeposition of etch and/or sputter products on feature surfaces.
Numerical results indicated that nanoscale convex features increase in size with increasing etching or plasma exposure time, and surface roughness increases with increasing ion incident energy. The ripple structures of etched surfaces were found to occur depending on incident angle of ions. Ion reflection or scattering on etched surfaces strongly affects the evolution of feature profiles and surface roughness on atomic scale.
[1] H. Tsuda et al., Jpn. J. Appl. Phys. (2011), in press.
[2] Y. Osano and K. Ono, J. Vac. Sci. Technol. B 26 (2008) 1425.
[3] H. Tsuda et al., Thin Solid Films 518 (2010) 3475.
[4] H. Tsuda et al., Jpn. J. Appl. Phys. 49 (2010) 08JE01.