Oxidation kinetics of SiGe alloy layer studied by real-time XPS

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

The oxidation of SiGe alloy layer is used for the concentration process of Ge in the CMOS devices. In this study, the oxidation reaction kinetics on SiGe alloy layers was investigated by real-time XPS to reveal the oxidation and Ge concentration kinetics. Experiments were performed at the BL23SU of SPring-8. Ge was deposited on the Si(001) surface at room temperature. After deposition, the sample was annealed at 933 K for 20 min. and then oxidized using oxygen gas at 773 K. The O 1s, Si 2p and Ge 3d photoelectron spectra were measured during oxidation. O 1s photoelectron intensity increased rapidly and then saturate after 2000 s. The oxidation rate on the SiGe alloy surface was slower than that of the Si clean surface. However, SiO component on the SiGe alloy surface increased. It was found that Ge was not oxidized. These results indicate that Ge atoms diffuse into Si substrate. This Ge diffusion may be caused by the oxidation-induced strain.