Effects of a SiO₂ capping layer on the electrical properties and morphology of nickel silicides

The effects of a SiO₂ capping layer on the electrical and structural properties of nickel silicide have been investigated as a function of rapid-thermal-annealing temperature. X-ray diffraction results show that regardless of the capping, NiSi phase is formed when annealed at temperatures ≥400°C, while NiSi₂ phase is formed at temperatures ≥700°C. For both the capped and uncapped samples, the sheet resistance increases with increasing temperature, although the former is better than the latter. It is shown that the capped samples exhibit better thermal stability than the uncapped samples. It is further shown that the reverse leakage current of the capped samples is about one order of magnitude lower than those of the uncapped ones.