Tetsuya Hoshino

Mechanism of polishing of SiO2 films by CeO2 particles

Abstract To examine the polishing mechanism in chemical mechanical polishing of a thermally grown SiO 2 film by CeO 2 particles, the surface structure of the film and the polishing waste were investigated by various analytical means. Fourier-transformed-infrared-attenuated-total-reflection (FT-IR-ATR) spectra indicated that the film surface structure was strained as a result of a reaction with CeO 2 . A small amount of Si was found by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) in the waste supernatant and it was detected as particles by optical interference measurement. The scanning electronic microscopy (SEM) image of the particles showed a not-well-defined shape like cotton scraps, but their IR transmission spectrum resembled that of the SiO 2 film. From these results we concluded that the SiO 2 film surface is first reacted with CeO 2 particles and a multiple number of chemical bondings of Si–O–Ce are formed on the surface. Then mechanical tearing of Si–O–Si bonds leads to the SiO 2 removal as a lump instead of Si(OH) 4 monomer, and the lump is released from the CeO 2 particles downstream.