4H-SiC MIS structures using oxidized Ta_2Si as high-k dielectric

摘要

Ta_2Si silicide has been deposited by sputtering and thermally oxidized on 4H-SiC and Si substrates. A mixture of SiO_2 and Ta_2O_5 insulator films has been obtained after oxidation in dry O_2. Among the high-k dielectrics, tantalum pentoxide (Ta_2O_5) could be a valuable alternative due to its high dielectric constant. Atomic force microscopy (AFM), C-V measurements along with x-ray diffraction analysis have been carried out in order to study the feasibility of this material as gate dielectric for 4H-SiC MOS devices. Electrical characteristics of deposited and oxidized Ta_2Si on 4H-SiC and Si samples have been obtained and compared. At the range of oxidation temperatures considered (850℃-950℃), the influence of diffusion processes between the Si substrate and Ta_2Si layer during oxidation strongly influences the dielectric properties of the resulting insulator layer on Si substrates.