Octahedral void structure observed in grown-in defects in the bulk of standard Czochralski-Si for MOS LSIs

We analyzed the structure of octahedral voids in the bulk of standard silicon wafers. They are often twin type and are about 100 nm in size. The structure of the defect is incompletely octahedron, and is mainly surrounded by {111} planes. Our electron diffraction and energy-dispersive X-ray spectroscopy analyses suggest that the octahedron defect is void. A 2-nm-thick layer exists on each of the side walls of the void defect. Our auger electron spectroscopy analysis suggests that the 2-nm-thick layer is SiO2. It is believed that the void structure is formed during Si-ingot growth.