Coverage dependence upon early oxidation stages of hafnium-adsorbed Si(111)-77

Hfが吸着したSi(III)-77の初期酸化状態の被覆率依存性

垣内 拓大*; 穴井 亮太*; 佐伯 大殊*; 津田 泰孝   ; 吉越 章隆 

Kakiuchi, Takuhiro*; Anai, Ryota*; Saiki, Taiju*; Tsuda, Yasutaka; Yoshigoe, Akitaka

Hf薄膜を形成したSi(111)基板の界面および表面の酸化プロセスを超音速酸素分子ビーム(SOMB)と放射光光電子分光法により研究した。0.5単層(ML)のHf-Si(111)は、HfSiとHfSiを含む。0.03eVの並進エネルギー(Et)を持つ熱酸素分子を照射すると、HfSiはHf価に酸化された。Etが0.39eVのSOMB照射により、他のHfSiはHfに酸化された。熱酸素曝露後、金属Hfはトラッピングを介した解離吸着を経てHfOに非局所的に酸化された。一方、偏析したSi原子は2.2eVのSOMB照射によって酸化され、表面にSiOが生成した。

0xidation at the interface and the surface of Si(111) substrate with thin Hf films were studied using synchrotron radiation photoelectron spectroscopy in conjunction with supersonic oxygen molecular beams (SOMB). An Hf/Si(111) with a coverage of 0.5 monolayer (ML) included HfSi and HfSi. Following exposures to thermal oxygen molecules with a translational energy (Et) of 0.03 eV, HfSi was oxidized into Hf valence. Following SOMB irradiation with Et of 0.39 eV, the other HfSi could be oxidized into the Hf. Following the thermal O exposures, the metallic Hf was nonlocally oxidized to HfO via trapping-mediated dissociative adsorption. Meanwhile, the segregated Si atoms were oxidized by SOMB irradiation with 2.2 eV and SiO was generated on the surface.