Characteristics of ohmic Ni/Si/Ni contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Ni/Si/Ni sputtered sequentially The annealings were performed at 950℃ using RTP in vacuum ambient and N₂ ambient, respectively. The specific contact resistivity(pc), sheet resistance(Rs), contact resistance (Rc) transfer length(LT) were calculated from resistance(RT) versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were pc = 3.8×10-5Ω㎠, Rc = 4.9 Ω and RT = 9.8 Ω, those of sample annealed at N₂ ambient were pc = 2.29×10-4Ω㎠, Rc = 12.9 Ω and RT = 25.8 Ω. The physical properties of contacts were examined using XRD 3nd AES. The results showed that nickel silicide was formed on SiC and Ni was migrated into SiC. This result indicates that Ni/Si/Ni ohmic contact would be useful in high performance electronic devices.
