Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1528591 | Materials Science and Engineering: B | 2015 | 6 Pages |
•Thin Ni–Si layers on SiC were studied after annealing.•Different types of microstructural defects occur depending on Ni:Si ratio.•Mechanisms leading to morphology degradation are discussed.•Presented method improves the microstructure of ohmic contacts to SiC.
The new approach to fabrication process of nickel-based ohmic contacts to silicon carbide (SiC) is presented. During the first annealing step (300 °C), the amorphous Ni–Zr layer retards diffusion between two nickel silicide layers, thus handling the contradictory requirements for optimal Ni:Si ratio. Different stoichiometry obtained in each silicide layer allows to preserve smooth interface with SiC and simultaneously to avoid relatively easily meltable Si-rich Ni–Si phases during high temperature annealing (1000 °C) and therefore prevents morphology degradation. After annealing at 1000 °C only one final nickel silicide layer is present and Zr atoms are agglomerated at its surface. Morphology of the final silicide layer is substantially improved when compared to typical Ni-based contacts obtained by similar high-temperature annealings. The improved microstructure of the ohmic contact is a promising advantage in terms of SiC devices reliability.