TITLE:
Dependence of Atomic-Scale Si(110) Surface Roughness on Hydrogen Introduction Temperature after High-Temperature Ar Annealing
AUTHORS:
Koji Araki, Ryuji Takeda, Haruo Sudo, Koji Izunome, Xinwei Zhao
KEYWORDS:
Si(110), Surface Roughness, Hydrogen Termination, High-Temperature Ar Annealing
JOURNAL NAME:
Journal of Surface Engineered Materials and Advanced Technology,
Vol.4 No.5,
August
6,
2014
ABSTRACT:
The atomic-scale
surface roughness of Si(110) reconstructed via high-temperature Ar annealing is
immediately increased by non uniform accidental oxidation during the unloading
process (called reflow oxidation) during high-temperature Ar annealing. In
particular, for a reconstructed Si(110) surface, characteristic line-shaped
oxidation occurs at preferential oxidation sites appearing in pentagonal pairs
in the directions of Si[-112] and/or [-11-2]. We previously reported that the
roughness increase of reconstructed Si(110) due to reflow oxidation can be
restrained by replacing Ar gas with H2 gas at 1000°C during the
cooling to 100°C after high-temperature Ar annealing. It was speculated that
preferential oxidation sites on reconstructed Si(110) were eliminated by H2 gas etching and hydrogen termination of dangling bonds. Thus, it is necessary
to investigate the effect of H2 gas etching and hydrogen termination
behavior on the reconstructed Si(110) surface structure. In this study, we
evaluated in detail the relationship between the temperature at which the H2 gas replaces the Ar in high-temperature Ar annealing and the reconstructed
Si(110) surface structure. The maximum height of the roughness on the
reconstructed surface was the same as if Ar gas was used when the H2 gas introduction temperature was 200°C, although the amount of reflow oxidation
was decreased to 70% by hydrogen termination. Furthermore, line-shaped oxidation
still occurs when H2 gas replaces Ar at this low temperature.
Therefore, we conclude that oxidation is caused by slight Si etching at low
temperatures, and thus the preferential oxidation sites on the reconstructed
structure must be eliminated by hydrogen etching in order to form an atomically
smooth Si(110) surface.