In situ observation of epitaxial microcrystals in thermally grown SiO2 on Si(100)

We succeeded with an in situ observation of the epitaxial microcrystal produced in thermally grown oxide on Si(100) by applying the grazing incidence diffraction of a synchrotron x ray. Oxidation was at 900 degrees C for 8 h in an environment of oxygen diluted with nitrogen, producing thermal oxides that were 122 Angstrom thick. During oxidation, we observed the diffraction peak corresponding to the epitaxial microcrystal, even in 23-Angstrom-thick oxide. The peak intensity increased as the oxidation proceeded but decreased by about 2/3 after cooling at the end of the oxidation. The lattice constant of the c axis of the microcrystal changed from 10.4 Angstrom for 23-Angstrom-thick oxide to 11.7 Angstrom for oxides thicker than 45 Angstrom. (C) 1999 American Institute of Physics. [S0003-6951(99)01218-8].