Influence of Al addition on phase transformation and thermal stability of nickel silicides on Si(001)

► The presence of Al slows down the Ni2Si–NiSi phase transformation but significantly promotes the NiSi2−xAlx formation. ► The behavior of phase transformation strongly depends on the Al concentration of the initial Ni1−xAlx alloys. ► The Ni0.91Al0.09/Si system exhibits remarkably improved thermal stability, even after high temperature annealing for 1000s. ► The relationship between microstructures, electrical property, and thermal stability of Ni(Al) silicides is discussed. The influence of Al addition on the phase transformation and thermal stability of Ni silicides on (001)Si has been systematically investigated. The presence of Al atoms is found to slow down the Ni2Si–NiSi phase transformation but significantly promote the NiSi2−xAlx formation during annealing. The behavior of phase transformation strongly depends on the Al concentration of the initial Ni1−xAlx alloys. Compared to the Ni0.95Pt0.05/Si and Ni0.95Al0.05/Si system, the Ni0.91Al0.09/Si sample exhibits remarkably enhanced thermal stability, even after high temperature annealing for 1000s. The relationship between microstructures, electrical property, and thermal stability of Ni silicides is discussed to elucidate the role of Al during the Ni1−xAlx alloy silicidation. This work demonstrated that thermally stable Ni1−xAlx alloy silicides would be a promising candidate as source/drain (S/D) contacts in advanced complementary metal–oxide-semiconductor (CMOS) devices.