IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Monday Sessions
       Session SC+SS-MoA

Paper SC+SS-MoA8
Structural Relaxation at SiO@sub 2@/Si(100) Interfaces Studied by Coaxial Impact Collision Ion Scattering Spectroscopy

Monday, October 29, 2001, 4:20 pm, Room 122

Session: Semiconductor Surfaces
Presenter: H. Ikeda, Nagoya University, Japan
Authors: H. Ikeda, Nagoya University, Japan
S. Goto, Nagoya University, Japan
K. Honda, Nagoya University, Japan
M. Sakashita, Nagoya University, Japan
A. Sakai, Nagoya University, Japan
S. Zaima, Nagoya University, Japan
Y. Yasuda, Nagoya University, Japan
Correspondent: Click to Email
With downsizing the ULSI devices, atomic bonding structures at the SiO@sub 2@/Si interface have become a serious factor to determine the device performance. Nevertheless, there are few studies about the interfacial structure. By using coaxial impact collision ion scattering spectroscopy (CAICISS), we have studied the structural changes extending over the first several layers from oxidized Si(100)-2x1 surfaces and claimed that the inward oxidation occurs before the lateral oxidation finishes.@footnote 1@ In the present study, we clarify Si atomic structures at the SiO@sub 2@/Si interface, which depend on the thickness of the oxide films and the oxidation temperature. An ion scattering simulation which is based on the consecutive calculation of the He@super +@ ion trajectories was used for the analysis of CAICISS spectra. Below an oxide thickness of 2.3 ML, the structural relaxation of a Si lattice at the SiO@sub 2@/Si interface occurs similarly in the range of room temperature to 700°C. The CAICISS spectra show only horizontal displacement of the second-layer Si atoms in these samples. In the following oxidation stage, the oxidation process depends on the temperature. At room temperature, the oxide thickness saturates at 2.3 ML, which is probably due to the restriction of oxygen adsorption on the distorted Si-Si bond sites. The CAICISS spectra of oxidation at above 300°C indicate interface structures that consist of Si atoms existing at normal lattice sites. Furthermore, vertical displacement of the second-layer Si atoms can be detected as well as horizontal one. From these results, it can be concluded that the vertical displacement of the second-layer Si atoms is a trigger of the formation of an amorphous structure and, moreover, a very abrupt SiO@sub 2@/Si interface is realized. @FootnoteText@ @footnote 1@ M. Wasekura, M. Higashi, H. Ikeda, A. Sakai, S. Zaima, Y. Yasuda, Appl. Surf. Sci., 159-160 (2000) 35.