Observation of oxidation-induced stacking faults by electron-acoustic microscopy

A high-power npn Tr-chip ( 5×5×0.2 mm 3 ) fabricated by high-temperature heat treatments on a dislocation-free Si (111) wafer was investigated using electron-acoustic microscopy (EAM). Part of the specimen was angle-lapped (3°) to partially expose the emitter and base layers, and the mechanically damaged layer was removed by chemical polishing with CP-4A. From the scanning electron microscopy and EAM images of the same site, right triangles with each side measuring about 30 µ m in length, arranged in the direction, were observed at the selected area. These images are oxidation-induced stacking faults (OSF) observed for the first time by EAM. These right triangles were distributed within the specimen and OSF existed not only on the specimen surface but also at depths of about 6 µ m from it.