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-hydr
ide on Si and degraded the hydrophobicity of the surface, while the di
-hydride on Si remained stable in the solution. These results explaine
d the crystal orientation dependence of the oxide removal from the Si
surface.