Dependence of Atomic-Scale Si(110) Surface Roughness on Hydrogen Introduction Temperature after High-Temperature Ar Annealing

Koji Araki, Ryuji Takeda, Haruo Sudo, Koji Izunome, Xinwei Zhao

Base Technology, Technology, Global Wafers Japan Co., Ltd., Niigata, Japan.
Department of Physics, Tokyo University of Science, Tokyo, Japan.

DOI: 10.4236/jsemat.2014.45028                

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.

Keywords

Si(110), Surface Roughness, Hydrogen Termination, High-Temperature Ar Annealing

Conflicts of Interest

The authors declare no conflicts of interest.

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