Evaluation of SiO2 films and SiO2/Si interfaces by graded etching

We have established a new preparation method for the evaluation of SiO2 films. The method. graded etching. a good replacement of conventional step etching. enables us to analyze the SiO2 films and the SiO2/Si interfaces in detail with much less effort. Three kinds of SiO2 films (HCl, dry and wet oxides) have been evaluated after graded etching. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) results revealed the presence of a SiOx (0 < x < 2) rich transition layer near the SiO2/Si inter-faces, the amount of which differs among the three kinds of oxides, AFM images also indicated that the SiO2 films were etched spottily at the beginning of etching. which results in different roughnesses of the etched surfaces for the three kinds of oxides.