Oxidation Of Micro-Fabricated Silicon-Crystals

Silicon mesa stripes and columns with a few 100 nm in size are fabricated on (100) Si wafer surfaces by a dry etching technique, and then thermally oxidized. Shapes of oxidized regions, stress distribution and dislocation generation in the regions are analyzed by means of transmission electron microscopy (TEM). In the oxidation of Si wafers having uneven surfaces, oxidation rate reduction due to the compressive stress within SiO2 occurs, and dislocations sometimes are observed with unusual structures. Such stress distribution in a sub-micron region can be analyzed by thickness measurement (measurement of thickness fringes) of the TEM sample, because the Ar ion etching rate in the sample preparation is anomalous in the stressed region.