Electrical properties of epitaxial NiSi_2/Si contacts with extremely flat interface formed in Ni/Ti/Si(001) system

摘要

We have investigated the morphology and the electrical properties of epitaxial NiSi_2/Si contacts formed in a Ni/Ti/Si(001) system. An atomically flat interface between an epitaxial NiSi_2 layer and a Si(001) substrate without {111} facets can be formed by annealing at 750℃. Glazing angle X-ray reflectivity measurements reveal that interface is extremely flat and uniform over areas as wide as about 1 mm~2. Local and inhomogeneous formation of Ni_4Ti_4Si_7 and C54—TiSi_2 grains are observed in the NiSi_2 layer and on the surface, respectively, after annealing at 850℃. The epitaxial NiSi_2 layer exhibits high thermal robustness compared to a NiSi layer formed in a conventional Ni/Si system and the sheet resistance of the epitaxial NiSi_2 layer formed in Ni/Ti/Si systems keeps the low value in the annealing at the temperature ranging between 650℃ and 850℃. Schottky barrier heights of this epitaxial NiSi_2/Si contacts for n- and p-type are estimated to be 0.30 and 0.37 eV, respectively.