Octahedral void defects observed in the bulk of Czochralski silicon

We found octahedral void defects in the bulk of silicon wafers by using infrared tomography. These voids are often twin type and their sizes are about 100 nm. A 2-nm-thick layer exists on the side walls of the void defects. Our analysis suggests that the 2-nm-thick layer is ${\mathrm{SiO}}_x.$ It is believed that the void structure is formed as a result of agglomeration of vacancies during Si–ingot growth.