Residual subsurface damages introduced by mirror polishing into Si CZ wafers degrade GOI in ULSI MOS devices. A removal of the damage throughout 9 times SC1 cleaning was systematically characterized as correlated between PCA signals measured by noncontact UV/mmwave technique, GOI at 10MV/cm for MOS diodes with a thin gate-oxide thickness of 10nm, surface microroughness Ra measured by AFM. The same characterization was carried out for epitaxial wafers, as reference. Degraded GOI and PCA signal were recovered throughout 3 times SC1 cleaning and did not depend on Ra of 0.1–0.2 nm, which led to that the damage causes the degradation of GOI, but it can be removed by 3 times SC1 cleaning, and the damage depth was about 21nm. Further, the PCA signal well reflects to removal of the damage and degradation of GOI so that it can be a monitor for characterizing the removal and GOI. Direct observation of the damage using OSDA was carried out for the epitaxial wafer polished and SC1 cleaned. The OSDA indicated an image involving straight lines which disappeared after 3 times SC1 cleaning. This gave a direct evidence for catching up it by PCA and existence of residual subsurface damages.
