Vibrational spectroscopic study of the interface of SiO₂/Si(100) fabricated by highly concentrated ozone: Direct evidence for less strained Si-O-Si bond angle

The interface structure of SiO₂/Si(100) synthesized with a highly concentrated ozone gas was analyzed by Fourier-transformed infrared absoption spectroscopy (FT-IR). The position of a transverse optical (TO) phonon peak of Si-O-Si asymmetric stretching vibration, which is a function of a Si-O-Si bond angle, remains constant at 1065 cm^-1 within a ∼2 nm thickness of an ozone-oxide film. This result indicates that the thickness of structural transition layers at this interface where the Si-O-Si angle is distorted due to the stress at the interface is considerably limited, which is in contrast to a thermal oxide film on Si(100) showing the existence of structural transition layers.