Oxidation reaction mechanism of SiGe/Si surfaces, 1; Temperature dependence of GeO formation

Hozumi, Hideaki*; Ogawa, Shuichi*; Yoshigoe, Akitaka ; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*

In order to make clear Ge concentration processes during oxidation of an SiGe alloy layer, Ge3d photoelectron spectra were observed during oxidation of an SiGe alloy layer using real-time XPS. All experiments were conducted using the surface reaction analysis apparatus at BL23SU in the SPring-8. A Ge layer was formed on the p-type Si(001) substrate with about 2 ML thickness by evapolation. The layer was annealed up to 993 K to form an SiGe alloy layer. The surface was oxidized in the O ambient of 5.010 Pa for 6400 s, and then further oxidation was made at 1.310 Pa for 5300 s. The surface temperature was room temperature and 773 K. In the case of 773 K, Ge atoms were not oxidized whereas Si atoms were selectively oxidized. The oxidation rate was faster than that of an Si(001) surface. These facts reveal that Ge atoms diffuse into the Si substrate due to SiO layer formation.