30.03.2023
Figure: Result of the hybrid measurement of a silicon nitride lattice sample. Varying the azimuthal angle, the fluorescence of nitrogen and oxygen (a), as well as the scattering of the first three diffraction orders (b) were measured at an excitation energy of 680 eV. Figure (a) also shows simulations of the local field distribution within a unit cell of the structure at different azimuthal angles.
The geometry of periodic nanostructures can be reconstructed non-destructively from combined X-ray scattering and fluorescence measurement data. For the application of this new hybrid technique using synchrotron radiation, a compact measurement chamber was developed and put into operation at BESSY II.
Typical GISAXS measurements (Grazing Incidence Small Angle X-ray Scattering) are performed under a very flat angle of incidence of the radiation on the sample. In the extreme ultraviolet (EUV) or soft X-ray spectral range, on the other hand, measurements of the scattering of radiation from structured samples are possible under relatively large angles of incidence of up to 30° (measured with respect to the surface), since the reflectivity of the materials used is generally higher there. The large angle of incidence results in two major advantages: First, the extent of the beam spot on the sample is reduced such that even relatively small, structured areas (100 µm²) can be investigated, which is relevant for samples from the semiconductor industry. Secondly, it is now possible to integrate the excitation and detection of X-ray fluorescence in the measurement chamber. Together with X-ray scattering, a second, complementary information channel is now available, which additionally offers the determination of the elemental distribution of a sample. Using a lattice sample of silicon nitrite, which is used as a standard for reconstruction measurements, this hybrid measurement method could be demonstrated for the first time with the new apparatus.
Link to publication:
R. Ciesielski, L. M. Lohr, , A. Fernández Herrero, et al. Review of Scientific Instruments 94(1), 013904 (2023)
https://doi.org/10.1063/5.0120146
Contact:
R. Ciesielski, 7.14, E-Mail: richard.ciesielski(at)ptb.de
V. Soltwisch, 7.14, e-mail: victor.soltwisch(at)ptb.de