Differential reflectance spectrum measurement to evaluate defects introduced by wet cleaning process

摘要

By employing differential reflectance spectrum (DRS) method, which can detect the small change of surface states with high sensitivity, reflectance change of silicon surfaces induced by a wet surface cleaning process is evaluated. Equally cleaned two surfaces are clarified to have almost same reflectance in the order of 10~(-4) in DRS. However, repeat of the cleaning leads to reflectance change in the order of 10~(-3) in the case of Si(111). The shape of the spectra is similar to that of oxidized surface which contains tensile strain at the interface. A conjecture on the origin of the spectrum change is proposed that the surface strain, which is generated by the repulsion between the adjacent hydrogen termination atoms, might affect. It should be noted that the small change of the surface atomic structure induced by the wet cleaning process result in the generation of the change of optical reflectance spectrum in the scale of 10~(-3).