Atomic Lineation of Products during Oxidation of Si(111)-7 × 7 Surface Using O₂ at 300 K

Abstract

Despite much attention for forming a uniform oxide film with a few atomic layers in modern Si semiconductor industry, the surface distribution and the chemical analysis of oxides have not been clear. In situ observation of an Si(111)-7 × 7 surface during exposing to O2 at 300 K was carried out using X-ray photoelectron spectroscopy, low-energy electron diffraction, and scanning tunneling microscope. Atomic lineation of products on the Si adatoms in the faulted-half side of the Si(111)-7 × 7 surface was revealed. We clarified that the minimum thickness of the oxide film, which covers the overall Si surface, was 0.35 nm. This study provides the physical picture of oxide-film formation mechanisms, which involves a mobile O2 on the surface and suggests the possibility to fabricate 1D atomic oxides.

Strong Temperature Dependence of the Initial Oxide Growth on the Si(111)7 × 7 Surface

“…Moreover, more adsorbed oxygen could insert into the backbond and diffuse to a deeper layer to form a thicker film with the temperature increased. The suggestion is compatible with the previous studied by STM which reported that the adsorbed oxygen molecules can agglomerate on the Si(111)7×7 surface [16] and also confirms the NEXAFS result that the incoming oxygen molecules can be trapped at the site where the oxygen atom has been inserted into the back bond [7,17]. Therefore, it was found that the thickness depends on temperature, which violated the DOS model, but it could be interpreted by the modified model.…”

Self‐accelerating oxidation on Si(111)7 × 7 surfaces studied by real‐time photoelectron spectroscopy

“…(b)) together with three peaks S1, S2, and S3 for clean Si surfaces. The S1, S2, and S3 peaks are assigned to Si rest atoms, Si adatoms, and pedestal Si atoms of the Si(111)7 × 7 surfaces and the energy‐loss satellite, respectively . The peak deconvolution parameters of the Si 2p 3/2 spectra are summarized in Table .…”

“…The S1, S2, and S3 peaks are assigned to Si rest atoms, Si adatoms, and pedestal Si atoms of the Si(111)7 × 7 surfaces and the energy-loss satellite, respectively. [11] The peak deconvolution parameters of the Si 2p 3/2 spectra are summarized in Table 1. The full width at half maximum (FWHMs) of the Lorentzian of all components was fixed in the curve fitting during the oxide growth.…”

“…The ability to simultaneously observe the oxidation rate and oxidation-induced strain is indispensable in clarifying the kinetics of initial oxide growth and interface oxidation. Real-time X-ray photoelectron spectroscopy (XPS) measurement is a powerful technique for its ability to measure not only oxidation states (Si 1+ , Si 2+ , Si 3+ , and Si 4+ [8][9][10][11] ) and oxide thickness, but also oxidation-induced strain on Si atoms at the SiO 2 /Si interface. In first-principle calculations from the Si 2p photoelectron spectra, a linear relationship between the chemical shifts and bond lengths of nonoxidized Si atoms (Si α , Si β ) has been found.…”

SiO Desorption Kinetics of Si(111) Surface Oxidation Studied by Real-Time Photoelectron Spectroscopy

“…The photon energy of the UV light was 21.22 eV with a take-off angle of 90 • (surface normal) and a surface sensitivity of 1 nm. The X-ray photoelectron spectroscopy (XPS) was performed at SUREAC2000 at BL23SU at Spring-8 [11,12], Japan. The photon energy and take-off angle values were 710 eV and 20 • , respectively.…”