Formation of source/drain junctions with a small parasitic series resistance is one of the key challenges for CMOS technology nodes beyond 100 nm. A new source/drain technology based on selective deposition of heavily in situ doped Si1-xGex layers was recently developed in this laboratory. This paper presents formation and structural characterization of self-aligned nickel germanosilicide contacts formed on heavily boron doped Si1-xGex alloys. The results show that thin NiSi1-xGex contacts with a resistivity of ∼25 μΩ-cm can be formed on Si1-xGex alloys at temperatures as low as 350°C. However, the low resistivity and the structural integrity of the NiSi1-xGex films can be maintained up to a maximum temperature of 450°C. At higher temperatures, Ge out-diffusion from NiSi1-xGex grains results in interface roughening and NiSi spikes. If the maximum processing temperature is kept within 400°C, p+-n junctions with excellent leakage behavior can be formed. A minimum contact resistivity of 2×10-8 Ω-cm2 is demonstrated for Ge concentrations above ∼40%, which can be linked to the smaller semiconductor bandgap and high boron activation under the metal contact. The results suggest that NiSi1-xGex contacts formed on Si1-xGex junctions have the potential to satisfy the contact resistivity requirements of future CMOS technology nodes.