Oxidation mechanisms of hafnium overlayers deposited on an Si(111) substrate

Kakiuchi, Takuhiro*; Matoba, Tomoki*; Koyama, Daisuke*; Yamamoto, Yuki*; Yoshigoe, Akitaka 

0xidation processes at the interface and the surface of Si(111) substrate with thin Hf films were studied using photoelectron spectroscopy in conjunction with supersonic oxygen molecular beams (SOMB). The oxidation starts at the outermost Hf layers and produces stoichiometric HfO. Hf silicates (Hf-O-Si configuration) were generated in the vicinity of the HfO/Si interface in the case of the irradiation of 2.2 eV SOMB. The oxidation of the Si substrate takes place to generate SiO compounds. Si atoms were emitted from the SiO/Si interface region underneath the HfO overlayers to release the stress generated within the strained Si layers. The emitted Si atoms can pass through the HfO overlayers and react with the impinging O gas.