We investigated SiO2 interfacial layer (IL-SiO2) reduction with a Ta2O5 cap to realize the direct contact formation of HfO2 on a Si substrate for the equivalent oxide thickness scaling of Hf-based high-k gate dielectrics. X-ray reflectivity and x-ray photoelectron spectroscopy measurements revealed that the Ta 2O5 cap was effective in taking oxygen from the IL-SiO2 and caused SiO2 reduction, which resulted from Ta diffusion into the HfO2 layer from the Ta2O5. With this technique, the Ta2O5 cap deposited on the HfO2/SiO2/Si reduced the IL-SiO2 by 0.2 nm without any thermal treatment. Rapid thermal annealing at 300 °C enhanced the IL-SiO2 reduction. This result reveals that our method is a promising approach to achieve direct contact between the high-k layer and the Si substrate. Therefore, Ta2O5 has good potential as a cap for SiO2 interfacial layer reduction.
ASJC Scopus subject areas
- Physics and Astronomy(all)