NiSi contact formation - process integration advantages with partial Ni conversion

Investigations for next generation contacts of silicon and SiGe devices show that a 2-step nickel salicidation process is favorable over a single step NiSi and over CoSi₂ in every respect and can be introduced easily in existing and advanced not fully depleted CMOS flows once the post silicidation thermal treatments can be kept below 700degC. Partial conversion for the deposited Ni layer to Ni₂ Si in a first RTP1 step at temperatures as low as 250degC avoids the reverse linewidth effect and enables superior uniformities over complete conversion. A second RTP2 step at typically 450degC is used to form low resistivity NiSi with less silicon consumption and lower contact resistivities than today´s CoSi₂ contacts. Challenging integration issue are peripheral leakage currents, that are likely to be related to undesired low temperature pyramidal NiSi₂ formation and spiking