SiO₂/Si Interfaces Studied by Scanning Tunneling Microscopy and High Resolution Transmission Electron Microscopy

Two types of SiO₂/Si(001) interfaces grown under wet and dry oxidation conditions have been studied by scanning tunneling microscopy (STM) and high resolution transmission electron microscopy (HRTEM). Hydrogen terminated Si surfaces were prepared for STM observations by stripping the oxide using aqueous HF acid. HRTEM was carried out using cross–sectional procedures. Fairly good agreement could be obtained between STM and HRTEM results for the “wet oxide” interface of metal oxide semiconductor structured samples. HRTEM results indicated that dry oxide interfaces showed somewhat larger values of roughness. Also, HRTEM of stripped oxide interfaces was also successfully carried out. On the whole, as for the dry oxide interface, it was more difficult to obtain a reproducible STM image than for the wet oxide interface, but the reverse was true for HRTEM owing to electron irradiation damage of the oxide itself.