SiO₂/Si Interfaces Studied by STM and HRTEM (II)

The morphology of the interfaces between Si(001) and thermal SiO₂grown by several oxidation conditions has been studied to compare the roughness of the interfaces observed, in particular, by STM and HRTEM. For STM observations, hydrogen-terminated Si surfaces were prepared by means of HF dipping. Dry oxide interfaces had irregularly distributed bumplike protrusions; in contrast, wet oxide interfaces revealed relatively flat features except for large undulations which localized sparsely. These morphological features ran along in the direction. It was difficult to obtain a reproducible STM image for dry oxide interface. The interface roughness of both wet and dry oxides resulted in higher values for the STM observation in comparison with HRTEM results. During the HRTEM observation, high-energy electrons damage the sample and reduce the oxide thickness by roughening the interface, especially in the wet oxide samples. a.