Effect of Hydrogen Termination on Surface Roughness Variation of Si(110) by Reflow Oxidation during High-Temperature Ar Annealing

Abstract

It is well known that a smooth surface can be realized for silicon (Si) wafers by Si surface reconstruction using high-temperature annealing. We previously reported that it is crucial to maintain a smooth reconstructed surface to restrict accidental oxidation during the unloading process (i.e., reflow oxidation) in high-temperature annealing. The surface roughnesses of both Si(100) and Si(110) were proved by suppressing the reflow oxidation. Furthermore, for suppressing the reflow oxidation, we evaluated the thickness of the reflow oxidation layer and the surface structure of the Si(110) wafer by replacing the injected Ar gas with H2 in the cooling process during high-temperature Ar annealing. The H2 atmosphere condition induced a change by etching the reconstructed surface, and the H-terminated surface on Si(110) formed SiH2, which effectively suppressed the reflow and characteristic line oxidations, resulting in a smooth terrace-and-step structure.