  GISAXS is often used as a versatile tool for the contactless and
destruction-free investigation of nanostructured surfaces. However, due to the
shallow incidence angles, the footprint of the X-ray beam is significantly
elongated, limiting GISAXS to samples with typical target lengths of several
millimetres. For many potential applications, the production of large target
areas is impractical, and the targets are surrounded by structured areas.
Because the beam footprint is larger than the targets, the surrounding
structures contribute parasitic scattering, burying the target signal. In this
paper, GISAXS measurements of isolated as well as surrounded grating targets in
Si substrates with line lengths from $50\,{\rm\mu m}$ down to $4\,{\rm\mu m}$
are presented. For the isolated grating targets, the changes in the scattering
patterns due to the reduced target length are explained. For the surrounded
grating targets, the scattering signal of a $15\,{\rm\mu
m}\,\times\,15\,{\rm\mu m}$ target grating structure is separated from the
scattering signal of $100\,{\rm\mu m}\,\times\,100\,{\rm\mu m}$ nanostructured
surroundings by producing the target with a different orientation with respect
to the predominant direction of the surrounding structures. The described
technique allows to apply GISAXS, e.g. for characterization of metrology fields
in the semiconductor industry, where up to now it has been considered
impossible to use this method due to the large beam footprint.
