  The increasing importance of well-controlled ordered nanostructures on
surfaces represents a challenge for existing metrology techniques. To develop
such nanostructures and monitor complex processing constraints fabrication,
both a dimensional reconstruction of nanostructures and a characterization
(ideally a quantitative characterization) of their composition is required. In
this work, we present a soft X-ray fluorescence-based methodology that allows
both of these requirements to be addressed at the same time. By applying the
grazing-incidence X-ray fluorescence technique and thus utilizing the X-ray
standing wave field effect, nanostructures can be investigated with a high
sensitivity with respect to their dimensional and compositional
characteristics. By varying the incident angles of the exciting radiation,
element-sensitive fluorescence radiation is emitted from different regions
inside the nanoobjects. By applying an adequate modeling scheme, these datasets
can be used to determine the nanostructure characteristics. We demonstrate
these capabilities by performing an element-sensitive reconstruction of a
lamellar grating made of Si$_3$N$_4$, where GIXRF data for the O-K$\alpha$ and
N-K$\alpha$ fluorescence emission allows a thin oxide layer to be reconstructed
on the surface of the grating structure. In addition, we employ the technique
also to three dimensional nanostructures and derive both dimensional and
compositional parameters in a quantitative manner.
