| AVS 61st International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS+AS+EN-MoM |
| Session: | Mechanistic Insights into Surface Reactions: Catalysis, ALD, etc. |
| Presenter: | Shuichi Ogawa, Tohoku University, Japan |
| Authors: | S. Ogawa, Tohoku University, Japan J. Tang, Tohoku University, Japan A. Yoshigoe, JAEA, Japan K. Nishimoto, Tohoku University, Japan S. Ishidzuka, Akita Nat. Col. Technol., Japan Y. Teraoka, JAEA, Japan Y. Takakuwa, Tohoku University, Japan |
| Correspondent: | Click to Email |
Thermal oxidation of Si is widely used in the fabrication of electric devices and MEMS. In the recent process, rapid thermal annealing (RTA) is used in a thermal oxidation process. In the RTA process, the temperature changes during the oxidation, but the temperature changing effects in the oxidation rate have not been cleared yet. In this study, the dependence of interface oxidation kinetics on the temperature was investigated by real-time RHEED combined with AES to measure the oxide growth rate. Based on the activation energy and pre-exponential factor of the interface oxidation at SiO2/Si(001) interface, the rate-limiting reaction of the interface oxidation is discussed.
The oxidation experiments were performed with an apparatus equipped with facilities of RHEED combined with AES (Tohoku Univ.), and chemical bonding states including not only suboxide components but also strained Si atoms were investigated XPS at BL23SU, SPring-8. The clean Si(001) surfaces were oxidized by dry O2 gas at initial temperature T1. When the clean surfaces were completely oxidized, the temperature was rised from T1 to T2. T1 was changed between room temperature (RT) and 561 °C.
When temperature was rised from T1 to T2, the interface oxidation is enhanced. The initial oxidation rate after rising temperature k2 is discussed in this study. The k2 strongly correlates to the difference of T1 and T2. The Arrhenius equations between k2 and T2 are obtained in various T1. As the result, activation energy is obtained as 0.27 eV in good agreement with the previous experimental result[1] and theoretical study[2]. In addition, it is found that activation energy is independent from T1. On the other hand, pre-exponential factor decreases with increasing T1, decreasing by about one order when T1 increases from RT to 561 °C. In the XPS results, the Si4+ component increases and suboxide components and strained Si components (Siα and Siβ)[3] decrease with temperature elevation from 300 to 600 °C.
Based on these results, we propose the reaction between point defects (emitted Si atoms and its vacancies) generated by the oxidation-induced strain and O2 molecules as the rate-limiting reaction of the interface oxidation.
[1] H. Watanabe et al., Phys. Rev. Lett. 80 (1998) 345.
[2] H. Kageshima et al, Jpn. J. Appl. Phys. 45 (2006) 7672.
[3] S. Ogawa et al., Jpn. J. Appl. Phys. 52 (2013) 110128.