Ohmic contacts to n-type 3C-SiC using Cr/Ni/Au and Ni/Cr/Au metallizations

Abstract

The electrical characteristics of Cr/Ni/Au and Ni/Cr/Au contacts to n-type 3C-SiC have been examined using a two-contact circular test structure. In Ni/Cr/Au contacts with Ni as contact layer and Cr as intermediate layer, both the modified sheet resistance, Rsk, and the specific contact resistance, ρc, have decreased continuously with increase in annealing temperature within the range 750–1000 °C. In comparison, the Cr/Ni/Au contacts with Cr as contact layer have exhibited a leveling-off in Rsk and increase in ρc after annealing at 900 and 1000 °C. These measurements have been correlated with depth profiles of the interfaces using Auger Electron Spectroscopy (AES). The AES profiles have shown a large-scale interdiffusion of the metal layers in the n-type 3C-SiC/Cr/Ni/Au structure after annealing at 750–1000 °C. In comparison, the n-type 3C-SiC/Ni/Cr/Au contacts have shown only a limited interdiffusion of the metals (Ni: Au)with the intermediate layer of Cr acting as a diffusion barrier for these metals.