Ring structures formed inside voids in SiO2 layer on Si(100) during thermal decomposition

Abstract

Ring structures inside voids in the SiO2 layer on a Si(100) substrate, which are concentrically formed by repeating thermal annealing in vacuum, have been investigated by scanning electron microscopy and atomic force microscopy. We demonstrate that slight exposure of the surface to volatile organic compounds during a cooling process significantly affects the formation of the ring structures. This result clearly shows that the key to ring-structure formation is surface adsorption of carbon atoms, which probably suppresses surface migration of silicon atoms. Our research provides a novel technique for the fabrication of nanostructured semiconductors for such applications as quantum effect devices.