IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS2-TuP

Paper SS2-TuP3
Generation of Type-C Defects on Si(100) by Bimolecular Adsorption of Water: A FT-IR, STM, AES and QMS Study

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Semiconductor Reactions Poster Session
Presenter: M. Nishizawa, Joint Research Center for Atom Technology (JRCAT), Japan
Authors: M. Nishizawa, Joint Research Center for Atom Technology (JRCAT), Japan
T. Yasuda, Joint Research Center for Atom Technology (JRCAT), Japan
S. Yamasaki, Joint Research Center for Atom Technology (JRCAT), Japan
K. Miki, National Institute of Advanced Industrial Science and Technology (AIST), Japan
M. Shinohara, Tohoku University, Japan
N. Kamakura, Tohoku University, Japan
Y. Kimura, Tohoku University, Japan
M. Niwano, Tohoku University, Japan
Correspondent: Click to Email
STM studies on various processes on Si(100)-(2x1) are often interfered with a high density of surface defects. Among three types of defects reported on this surface,@footnote 1@ the structure of the so-called type-C defect has been under debate. We show that the C-defects are generated by adsorption of water from the UHV environment. This conclusion is based on our systematic investigations using FT-IR, STM, AES, and QMS. Our STM experiments have reproduced the commonly observed phenomenon that the C-defect density increases with time even when the vacuum is as good as 10@super -11@ Torr. The surface with many C-defects shows a small but detectable O@sub KLL@ signal in AES. A possible source of O is the residual H@sub 2@O, CO, and/or CO@sub 2@ in UHV. To identify the source of surface O, we examined the correlation between the generation rate of the C-defects and the partial pressures for these gases. We have found that H@sub 2@O, which adsorbs at a sticking probability near unity, is the only candidate that can account for the defect generation rate. Dissociative adsorption of residual H@sub 2@O has been indeed detected by our IR measurements in which Si-H and O-H stretching modes are observed. The Si-H band has two components indicating that there are two kinds of Si-H bonds of different configurations. In addition, kinetic analyses of the Si-H evolution have revealed that the adsorption takes place via highly mobile precursor states. These observations suggest that C-defects are generated by bimolecular adsorption of H@sub 2@O, which readily explains the STM observation that the C-defects occupy two dimers. The detailed structure of the C-defect will be discussed at the presentation. This study, partly supported by NEDO, was performed at JRCAT under the joint research agreement between AIST and ATP. @FootnoteText@ @footnote 1@ Hamers et al., J. Vac. Sci. Technol. A 7 (1989) 2854.