| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science Poster Session |
| Presenter: | T. Nagaoka, Kyoto University, Japan |
| Authors: | T. Nagaoka, Kyoto University, Japan H. Ohta, Kyoto University, Japan K. Eriguchi, Kyoto University, Japan K. Ono, Kyoto University, Japan |
| Correspondent: | Click to Email |
Dry processing technology with chemically reactive plasmas has been widely utilized for the fabrication of semiconductor devices. At present, HBr plasmas are standard for Si etching processes (e.g., gate etch and shallow trench isolation etch in the fabrication of SRAM). Here we first report molecular dynamics (MD) simulation of Si etching by HBr or Br2 plasmas. The Simulation procedure is as follows. In the 3D simulation cell (cross section=3.22 nm2, depth = about 5 nm), about 1,500 silicon atoms are initially located in the structure of diamond lattice. Atoms in the bottom layer are fixed and periodical boundaries are imposed in the horizontal direction. To this Si(100) substrate, 20-300 eV ions are impinged in the direction normal to the surface. In this study, we used an improved Stillinger-Weber interatomic model partially including multibody interaction. Parameter sets for Si/H/Br were newly determined based on ab-initio data. We focused on monochromatic beam etching by Br+ (Cl+), Br2+ (Cl2+), H+, and HBr+ ions without radicals. First, we confirmed the different etching characteristics between cases of Br and Cl. Yields by Br+ and Br2+ were lower than those by Cl+ and Cl2+ at the same ion energy. This tendency agrees with experimental results.1 Additionally, yields by diatomic ions were higher than those by monatomic ions. The energy dependence of etch yield will be presented. Secondly, we estimated the halogen coverage. The Br coverage for Br+ impact was lower than Cl coverage for Cl+ impact. For the case of Br+ with an ion energy of 50 eV, the depth of reaction layer and Br coverage were about 20 Å and 7.7×1014 cm-2, respectively. On the other hand, for Cl+ impact, the depth of the reaction layer and Cl coverage were about 30 Å and 1.7×1015 cm-2, respectively. These coverages are in good agreement with experimental results of 6.0×1014 cm-2 and 1.0×1015 cm-2 using HBr and Cl2 plasmas, respectively, where a dc bias voltage is -35V.2 In this conference, the effect of H+ on etching mechanisms will be also discussed.
1S. A. Vitale et al., J. Vac. Sci. Technol. A 19,2197 (2001).
2 C. C. Cheng et al, J. Vac. Sci. technol. A 13,1970 (1995).