Ta_2Si short time thermal oxidized layers in N_2O and O_2 to form high-k gate dielectric on SiC

摘要

In this work, we report on two properties of the oxidation of tantalum silicide (Ta_2Si) on SiC substrates making this material of interest as insulator for many wide bandgap or compound semiconductors. The relatively high oxidation rate of tantalum silicide to form high-k insulator layers and its ability for being oxidized in diluted N_2O ambient in a manner similar to the oxidation in O_2 are investigated. Metal-insulator-semiconductor capacitors have been used to establish the actual applicability and constrain of the high-k insulator depending on the oxidation conditions. At 1050℃, the reduction of the oxidation time from 1 h to 5 min affects primordially the SiO_x interfacial layer formed between the bulk insulator and the substrate. This interfacial layer strongly influences the metal-insulator-semiconductor performances of the oxidized Ta_2Si layer. The bulk insulator basically remains unaffected although some structural differences arise when the oxidation is performed in N_2O.