Ordering in thermally oxidized silicon

We present new evidence and a model for residual ordering of silicon atoms within the oxide of thermally oxidized silicon wafers. X-ray scattering is used to observe the residual order in thermally grown SiO2 on Si(001), (011), and (111) surfaces with thicknesses of 60 to 1000 Angstrom, for both on-axis and miscut surfaces. In every case, the scattering position can be predicted using a model which expands the silicon lattice during oxidation without completely disordering it. The amount of expansion and disorder is dependent on the type of oxidation process employed.