Semiconductor devices have multilayer interconnection to achieve high density circuit. In the fabrication process, due to necessity of the flatness and the smoothness of each layer, CMP is widely used. However in the conventional copper-CMP process, the abrasive grain for the slurry has a problem to apply to the next design rule, due to their large particle sizes. Thus, water soluble fullerenol, C60(OH)36 whose particle size is quite small (<1 nm), and has high quality planarization efficiency, is proposed as the abrasive grain for copper-CMP. In this study, to determine the mechanism of the copper-CMP process using water soluble fullerenol, the generation of oxidized film is investigated, and on the surface of wafer, generation of a large amount of porous film is confirmed. Furthermore, in the case with and without C60(OH)36, the different materials appeared on the film. Therefore, it is considered that C60(OH) 36 has chemical effect that alters surface condition in this process.