Masaharu Udagawa

Local Ordering and Lateral Growth of Initial Thermal Oxide of Si(001)

The initial stages of the thermal (600 o C) oxide growth of Si(001) clean surfaces were studied by scanning tunneling microscopy (STM). Oxide growth starts from both step edges and terraces. At 120L, almost the entiresurface was covered by oxides. Steps could still be identified, and the apparent roughness had a local minimum at this O 2 exposure. These results indicate that the first layer is oxidized quite uniformly. Some local orderings of the initial oxides were observed on the terraces, which may enhance the oxide growth in the lateral (parallel to the surface) direction

Atomic‐scale planarization of SiO2/Si(001) interfaces

Atomically flat silicon‐oxide interfaces were obtained after preparing the Si(001)‐2×1 reconstructed surface in ultrahigh vacuum (UHV) followed by native oxide growth and then conventional thermal oxidation. When the surface is prepared with conventional wet cleaning prior to oxidation, the flat interfaces initially tend to become rough and then smoother with increasing oxide thickness. In comparison with the conventional interfaces, UHV surface planarization is significant up to oxide thicknesses of about 8 nm. This thickness range will be extremely important for future ultralarge‐scale integrated circuits (ULSIs).