Behavior of Emitted Si Atoms for the Initial Stage of Oxidation on Si(100)-(2*1) Surface Observed by Scanning Tunneling Microscope

Abstract

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 380℃, O2 exposure induced the formation of onedimensional 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.

Strong Temperature Dependence of the Initial Oxide Growth on the Si(111)7 × 7 Surface

“…Band bending due to the generation of defects at the Si/SiO 2 interface also affects the work function. When the Si surface is oxidized, the Si atoms move from the interface to the surface [18] and into the oxide [1], and defects are generated at the interface. Simultaneously, the interface state density also increases, which causes band bending.…”

Roles of strain and carrier in silicon oxidation

“…172,173) They agglomerate to dimer rows as observed by STM at 380 °C. 91) By elongating the surface migration length of the emitted Si atom with elevating temperature, it is expected that the Si growth mode changes from the 2D Si island growth to the step-flow growth. 176,177) A ratio between the 1 × 2 and 2 × 1 domains on the Si(001)2 × 1 surface, R 1 × 2/2 × 1 , is estimated by I (1/2 0) /I (0 1/2) of RHEED patterns.…”

“…Angle-resolved XPS was also employed to measure the depth profile of SiO near the SiO 2 surface to clarify the reaction between SiO and O 2 molecules in the SiO 2 film. 74) In this paper, we review the study of the unified Si oxidation reaction model mediated by point defect generation: The competition between the SiO 2 growth and decomposition, [74][75][76] the phase transitions in the surface oxidation, [77][78][79][80][81][82][83][84][85] the SiO 2 decomposition kinetics, 86,87) the lattice site of the adsorbed O atom, 88,89) the correlation between the SiO 2 growth rate and the SiO 2 decomposition rate, 90) the Si emission kinetics, 72,91) the self-accelerating oxidation, 92) the thermal strain-induced enhancement of dX O /dt, 93) the P O2 dependence of dX O /dt, 94) the temperature and P O2 dependence of dX O /dt during the layer-by-layer oxidation, 95) the oxidation reaction kinetics of the Si 1−x C x alloy layer (x ; 0.1) formed on Si(001) surfaces. 96) This review paper consists of five chapters.…”