Atomic-Order Planarization of Ultrathin SiO₂/Si(001) Interfaces

Abstract

Conventional wet cleaning and ultrahigh vacuum (UHV) heated cleaning prior to thermal oxidation were compared with respect to their effects on extremely thin SiO 2 /Si(001) interface roughness. Atomically flat SiO 2 /Si(001) interfaces were realized by preparing the Si(001) reconstructed surface in UHV followed by thermal oxidation. In contrast to conventional wet cleaning, this planarization is significant in the range of oxide thickness ( T ox )<9 nm which is an important thickness for future gate oxides. As for the conventional wet-cleaned surfaces, maximum roughness of the interface was observed at T ox ≃4 nm which corresponds to the “initial oxide thickness” which appeared in the oxide growth kinetics.