GIXRF in the soft X-Ray range used for the characterization of ultra shallow junctions

Grazing incidence X-Ray fluorescence (GIXRF) analysis in the soft X-ray range provides excellent conditions for exciting B-K and As-Liii,ii shells. The X-ray Standing Wave field (XSW) associated with GIXRF on flat samples is used as a tunable depth sensor to gain information about the implantation profile. This technique is very sensitive to near surface layers. It is therefore well suited for the study of ultra shallow dopant distributions. Arsenic implanted (implantation energies between 0.5 keV and 5.0 keV) and Boron implanted (implantation energies between 0.2 keV and 3.0 keV) Si wafers have been used to compare SIMS analysis with GIXRF analysis. The measurements have been carried out at the electron storage ring BESSY II using monochromatized undulator radiation of well-known radiant power and spectral purity. The use of an absolutely calibrated energy-dispersive detector for the registration of the B-Kα and As-Lα fluorescence radiation allows for the absolute determination of the retained dose. An estimate of the concentration profile has been obtained by fitting the measurements with profiles derived by simulation of the implantation process. A good match among the total retained dose measured with the different techniques has been observed.