Study of high-κ/strained-Ge channel and high-κ/strained-Si channel using X-ray Photoelectron Spectroscopy

We have investigated the influence of Si-cap layer and the post deposition annealing(PDA) on compositional depth profiles and chemical structures of HfO_2/Si-cap/strained Ge/SiGe/Si interfaces by angle-resolved X-ray photoelectron spectroscopy. Analyses of Ge 2p, Si 1s and Hf 3d spectra show that strained-Ge layer is oxidized during the deposition of HfO_2 in the case of an 1-nm-thick Si cap layer, while the Ge layer is not oxidized in the case of an 3 and 5-nm-thick Si cap layer. In other words, the oxidation of Ge is prevented by the existence of bulk-Si.