Microstructure of Bulk-Type Multiple Stacking Faults in Silicon Crystals

Silicon specimens containing stacking faults (SFs) are cut out of Czochralski-grown wafers for observation with a transmission electron microscope (TEM). 〈100〉-oriented silicon wafers normally used for large scale integrated circuit devices are subjected to thermal treatments in N2 and O2 ambients in order to form bulk-type SFs. Then, TEM specimens are carefully prepared for observing the whole image of the SF in the fault plane. For this purpose the specimen is cut off along the {111} plane being inclined from the (100) wafer surface by 55 degrees. It is found that a bulk-type multiple stacking fault consists of a cluster of SiO2 precipitates located in the center of a circular Frank dislocation loop, and of many SiO2 precipitates on the loop.