Surface treatment effects on microscopic Si surface structure and SiSiO2 interface state

Surface treatment effects on the micro-morphology of Si(111) surface and interface state density (Dit) of the Si(111)SiO2 prepared by photo-induced chemical vapor deposition (photo-CVD) have been investigated by atomic force microscopy (AFM) and deep level transient spectroscopy (DLTS) method. Well-ordered atomic steps and flat terraces are clearly observed on the Si(111) surfaces treated in NH4F solution or in boiled deionized water. For these atomically flat substrates, the values of Dit become less than that of the sample treated by 1%HF solution. In addition, F2 treatment effects before SiO2 growth have also been examined by AFM, DLTS method and photo I-V method. The value of Dit is decreased at the substrate temperature below 250°C with minimal value at about 200°C. Electron scattering length near the interface is not changed by the F2 treatment.