We have investigated the chemical reaction at the interface between polycrystalline-Si (poly-Si) electrodes and Hf O2 Si gate dielectrics by photoemission spectroscopy and x-ray absorption spectroscopy depending on the annealing temperature in an ultrahigh vacuum. From Si 2p and Hf 4f high-resolution core-level photoemission spectra, we revealed that the Hf-silicide formation starts at as low temperature as 700 °C and that the Hf-silicate layer is also formed at the interface between poly-Si electrodes and Hf O2. Crystallization of the amorphous Hf O2 layer even at 700 °C was suggested from valence-band and O K -edge absorption spectra. By the annealing at 800 °C, the Hf O2 layer disappeared completely and the Hf-silicide clusters were formed on the Si substrate. Direct contact between poly-Si electrodes and Hf O2 promotes the interfacial reaction compared to the case without poly-Si electrodes.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)