Thermal Silicidation of Ni/SiGe and Characterization of Resulting Nickel Germanosilicides

Abstract

Thermal silicidation characteristics of Ni/Si1-xGex with various Ge content was studied under different annealing temperatures in the range of 225 °C ∼ 400 °C in 100% N2 ambient. TiN capped Ni/Si1-xGex/Si/SiO2/Si wafers with x values in the range of 0.15 and 0.30 in 0.05 intervals were used. Thermal silicide formation was performed in a stacked hotplate-based annealing system designed for industrial 300 mm wafer fabs. For silicide characterization, measurements of spectral reflectance, sheet resistance, Raman spectra as well as X-ray diffraction curves were performed to investigate changes of optical properties, electrical properties, crystallographic phases during silicide formation. Effects of Ge content and annealing temperature on the electrical and crystallographic properties of the resulting thermal silicides (nickel germanosilicides) were investigated. Reaction mechanisms were discussed based on the characterization results. Multiwavelingth micro-Raman spectroscopy was found to be very promising as a non-contact, in-line silicidation process monitoring technique. For production worthiness verification of the thermal silicidation process, temperature sensitivity curves of sheet resistance, its uniformity and detailed sheet resistance maps were investigated using 8 nm thick Ni films on 300 mm diameter, epitaxial Si0.8Ge0.2/p−-Si wafers without a capping layer. Manufacturability of Ni/Si0.80Ge0.20/Si wafers were also verified using a stacked hotplate-based, nearly isothermal, annealing system.