Si(100)-(2×1)表面の初期酸化過程における放出Si原子挙動の走査型トンネル顕微鏡観察

Changes of surface structure for the initial stage of oxidation in the Langmuir type adsorption range on Si(100)-(2×1) surfaces were observed using a scanning tunneling microscope (STM). On the Si(100)-(2×1) surfaces exposed to oxygen (O2) at room temperature, bright spots located on the center of a dimer row and dark sites appeared, and increased in number with increasing of O2 exposure. It is considered that the bright spots correspond to the isolated Si dimer emitted by the oxidation-induced strain at SiO2/Si interface. At 380oC, O2 exposure induced the formation of one-dimensional Si islands and an SB step flow growth due to the surface diffusion of the emitted Si atoms. These STM observation results clarify that the SB step flow growth causes the decrease of 1×2/2×1 domain ratio and the behavior of emitted Si atoms support the unified Si oxidation reaction model proposed by Takakuwa.