A new sample chamber for hybrid detection of scattering and fluorescence, using synchrotron radiation in the soft x-ray and extreme ultraviolet (EUV) spectral range.

Smaller and more complex nanostructures in the semiconductor industry require a constant upgrade of accompanying metrological methods and equipment. A central task for nanometrology is the precise determination of structural features of gratings in the nanometer range as well as their elemental composition. Scatterometry and x-ray fluorescence in the soft x-ray and extreme ultraviolet spectral ranges are ideally suited to this task. We here present a new, compact measurement chamber that can simultaneously detect the elastically scattered signal and the fluorescence, originating from nanoscale grating samples. Its geometry enables detecting scattered intensity over a wide angular range with a variable angle of incidence. We show first experiments on industry-relevant test structures from the commissioning process alongside the specifications of the setup, located at PTB's soft x-ray radiometry beamline at the synchrotron radiation facility BESSY II in Berlin.

Uncertainties in the reconstruction of nanostructures in EUV scatterometry and grazing incidence small-angle X-ray scattering.

Increasing miniaturization and complexity of nanostructures require innovative metrology solutions with high throughput that can assess complex 3D structures in a non-destructive manner. EUV scatterometry is investigated for the characterization of nanostructured surfaces and compared to grazing-incidence small-angle X-ray scattering (GISAXS). The reconstruction is based on a rigorous simulation using a Maxwell solver based on finite-elements and is statistically validated with a Markov-Chain-Monte-Carlo sampling method. It is shown that in comparison to GISAXS, EUV allows to probe smaller areas and to reduce the computation times obtaining comparable uncertainties.

Modeling and empirical characterization of the polarization response of off-plane reflection gratings.

Off-plane reflection gratings were previously predicted to have different efficiencies when the incident light is polarized in the transverse-magnetic (TM) versus transverse-electric (TE) orientations with respect to the grating grooves. However, more recent theoretical calculations which rigorously account for finitely conducting, rather than perfectly conducting, grating materials no longer predict significant polarization sensitivity. We present the first empirical results for radially ruled, laminar groove profile gratings in the off-plane mount, which demonstrate no difference in TM versus TE efficiency across our entire 300-1500 eV bandpass. These measurements together with the recent theoretical results confirm that grazing incidence off-plane reflection gratings using real, not perfectly conducting, materials are not polarization sensitive.