In this work, metallizations suitable for SiC devices and stable at high temperatures furthermore working in harsh environment are investigated. The Au/TiW/Ni2Si multilayer has been studied concerning its physical and chemical stability, and its electrical behaviour at several temperatures up to 600degreesC in air. Depth profiling by XPS and x-ray diffraction were used to study the thermal stability of TiW films as diffusion barriers between a gold overlayer and the Ni2Si/SiC ohmic contact. Transmission line model (TLM) was adopted to measure the contact resistivity and to test the electrical stability upon thermal stresses. Measurements were performed on samples before and after thermal stresses at temperature ranging from 200degreesC to 600degreesC in vacuum and O-2 environment. We demonstrate that the metallization scheme is reliable up to 450degreesC for 100 hrs.