Characterisation of ultra-shallow disorder profiles and dielectric functions in ion implanted Si

Ultra-shallow (below 20 nm) disorder profiles have been characterized by spectroscopic ellipsometry (SE). The implanted depth region has been divided into sublayers with dielectric functions calculated by the effective medium approximation using single-crystalline and disordered components. The damage depth profile has been parameterized using a box model, an independent multilayer model, a graded multilayer model, an error function, and Gaussian profiles. Literature values and Tauc-Lorentz (TL) parametrization as well as multi-sample and single-sample approaches have been compared to describe the dielectric function of the disordered component. The distribution of the implanted ions and/or damage have been cross-checked using medium energy ion scattering (MEIS), transmission electron microscopy and Monte Carlo simulations. We found a good agreement in the damage profiles obtained by the different methods. There is an offset between the SE and MEIS damage profiles due to the fact that SE is very sensitive to the surface roughness, in contrast to MEIS. The correlation between this offset and the surface roughness has been investigated using atomic force microscopy.