Schottky Barrier Characteristics of Cobalt-Nickel Silicide/n-Si Junctions for Scaled-Si CMOS Applications

Ternary cobalt-nickel silicide/n-Si Schottky diodes have been fabricated by sputtering using an equiatomic cobalt- nickel alloy target. A minimum sheet resistivity of the ternary silicide is found to be 5-7 Omega/sq. Grazing-incidence X-ray diffraction shows the formation of ternary silicide phases. Cross-sectional TEM micrograph shows a fairly uniform diffusion of metals into Si with the formation of fully silicided film. Selected-area electron diffraction pattern exhibits the crystalline nature of the silicide layer. Temperature-dependent electrical current-voltage measurements have been used to characterize an optimized Schottky diode formed by annealing at 450degC. The room-temperature barrier height and ideality factor are found to be 0.656 eV and 1.6, respectively, from the I-V characteristics. The series resistance of the diode has been calculated and is found to be 1-11.8 kOmega. The variation of barrier height has been attributed to the inhomogeneity in Schottky junction.