Effects of reaction product during hydrogenation of Si surfaces in HF solution

The reaction between the H-terminated Si surfaces and H2SiF6 solution, which is a reaction product of the dissolving SiO2 in the HF solution, was examined. The H2SiF6 solution selectively oxidized the mono-hydride on Si and degraded the hydrophobicity of the surface, while the di-hydride on Si remained stable in the solution. These results explained the crystal orientation dependence of the oxide removal from the Si surface.