Characterization of silicide stacks by combination of spectroscopic ellipsometry and reflectometry

In this work we show that by combining spectroscopic ellipsometry with reflectometry in the wavelength range from visual to deep ultraviolet the characterization of silicide (NiSi and CoSi2) stacks can be performed by determination of optical constants and thickness of all stack components. Especially, the diagnostic of the surface layer on silicide structures has been performed. By this way non-destructive monitoring of silicidation process was improved. Additional methods such as X-ray photoelectron spectroscopy and atomic force microscopy were used to confirm the results. Different impacts of type and thickness of initial metal (Co or Ni), protective cap layer type (Ti or TiN), and rapid thermal process temperature. on surface and silicide layers formation were found.