It is found from X-ray photoelectron spectroscopy study on the chemica
l structure of silicon dioxide, whose thickness is in the range of 1.2
nm to 8.6 nm, that the oxidation-induced chemical shift depends mainl
y on the distance, and that 0.4- and 0.6-nm-thick preoxide, which is f
ormed in dry oxygen at 300 degrees C, modifies the structure of oxide
near the surface.