Improved microstructure and ohmic contact of Nb electrode on n-type 4H-SiC

Niobium was deposited as an electrode material on an n-type SiC wafer for power device application. The reaction microstructure and electrical contact property were investigated after annealing at 700 to 1000 °C and compared with the results for an Ni electrode. Microstructure-related problems of the Ni electrode could be resolved without sacrificing ohmic contact behavior with a low contact resistivity of 1.53 × 10− 4 Ω cm2. Carbon precipitation was completely eliminated with Nb by the formation of carbides, leading to good adhesion upon wire bonding process. At the reaction interface, Nb5Si3 was formed in an epitaxial relationship with SiC, leading to a good interface contact property as well as good interface adhesion.

► Niobium was investigated as an electrode material on an n-type SiC wafer.
► Microstructure problems of Ni electrode, resolved preserving its ohmic behavior.
► Carbon precipitation was eliminated with the formation of carbides.
► Mechanical property was improved by elimination of carbon.