Chemical reaction at the interface between polycrystalline Si electrodes and HfO2/Si gate dielectrics by annealing in ultrahigh vacuum -: art. no. 012903

We have investigated the chemical reaction at the interface between polycrystalline-Si (poly-Si) electrodes and HfO2/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 degrees C and that the Hf-silicate layer is also formed at the interface between poly-Si electrodes and HfO2. Crystallization of the amorphous HfO2 layer even at 700 degrees C was suggested from valence-band and O K-edge absorption spectra. By the annealing at 800 degrees C, the HfO2 layer disappeared completely and the Hf-silicide clusters were formed on the Si substrate. Direct contact between poly-Si electrodes and HfO2 promotes the interfacial reaction compared to the case without poly-Si electrodes. (c) 2005 American Institute of Physics.