AVS 45th International Symposium
    Surface Science Division Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA7
Study on Photon Energy Dependence of Laser-Induced Chlorine Reaction on Si(111)

Tuesday, November 3, 1998, 4:00 pm, Room 314/315

Session: Photon- and Electron-Induced Chemistry
Presenter: S. Haraichi, Electrotechnical Laboratory, Japan
Authors: S. Haraichi, Electrotechnical Laboratory, Japan
F. Sasaki, Electrotechnical Laboratory, Japan
Correspondent: Click to Email
A photo-induced etching is considered as a powerful candidate of the next-generation device fabrication process from the view point of extremely low damage. However the atomic mechanism of the photo-induced surface reaction has not been well understood. We have investigated photon energy dependence of laser-induced chlorine reaction on Si(111) to elucidate the resonant reaction of this system using surface reflectance spectroscopy (SRS) and second-harmonic generation (SHG). In the SRS study, reflectance spectra from an initial oxidized, a cleaned 7x7, and a chlorinated Si(111) surface have been measured by the p-polarized light at the incident angle of around 74°, which is Brewster angle of silicon, with the photon energy ranging from 3.0 to 5.0 eV. Reflected lights themselves have a peak at around 3.4 eV involving the direct band gap transition E@sub 1@ in bulk silicon, however, the peak intensity shows no significant change due to the variation of the surface condition. On the other hand, the reflectance spectra have a peak at around 4.4 eV whose value changes remarkably due to the surface condition and is probably concerned with some surface states. The threshold laser fluency of etching reaction dependence on the photon energy ranging from 1.5 to 2.5 eV has been studied by the SHG method. The threshold fluency shows the minimum value at around 2.15 eV whose SH energy of 4.3 eV is almost equal to the above surface originated peak of the reflectance spectra. The time constant of the on- and the off-resonant reaction will also be discussed.