Scan-Free GEXRF in the Soft X-ray Range for the Investigation of Structured Nanosamples

Abstract

Scan-free grazing-emission X-ray fluorescence spectroscopy (GEXRF) is an established technique for the investigation of the elemental depth-profiles of various samples. Recently it has been applied to investigating structured nanosamples in the tender X-ray range. However, lighter elements such as oxygen, nitrogen or carbon cannot be efficiently investigated in this energy range, because of the ineffective excitation. Moreover, common CCD detectors are not able to discriminate between fluorescence lines below 1 keV. Oxygen and nitrogen are important components of insulation and passivation layers, for example, in silicon oxide or silicon nitride. In this work, scan-free GEXRF is applied in proof-of-concept measurements for the investigation of lateral ordered 2D nanostructures in the soft X-ray range. The sample investigated is a Si3N4 lamellar grating, which represents 2D periodic nanostructures as used in the semiconductor industry. The emerging two-dimensional fluorescence patterns are recorded with a CMOS detector. To this end, energy-dispersive spectra are obtained via single-photon event evaluation. In this way, spatial and therefore angular information is obtained, while discrimination between different photon energies is enabled. The results are compared to calculations of the sample model performed by a Maxwell solver based on the finite-elements method. A first measurement is carried out at the UE56-2 PGM-2 beamline at the BESSY II synchrotron radiation facility to demonstrate the feasibility of the method in the soft X-ray range. Furthermore, a laser-produced plasma source (LPP) is utilized to investigate the feasibility of this technique in the laboratory. The results from the BESSY II measurements are in good agreement with the simulations and prove the applicability of scan-free GEXRF in the soft X-ray range for quality control and process engineering of 2D nanostructures. The LPP results illustrate the chances and challenges concerning a transfer of the methodology to the laboratory.

Angle-Dependent XRF Analyses: Pros and Cons of a Novel Technique in the Field of Cultural Heritage

“…A similar task can also be achieved by properly adjusting the geometry of analysis: with angle-dependent XRF, we refer to all the XRF techniques that employ an angular variation during the analysis of the sample; depending on the angular range, we can have grazing techniques (i.e., grazing incident, GI, and grazing emission, GE-XRF) [66][67][68][69][70][71][72] and the more general angle-resolved (AR) XRF [73][74][75][76].…”

2023 atomic spectrometry update – a review of advances in X-ray fluorescence spectrometry and its special applications

“…Lamellar Si 3 N 4 nanostructured gratings with SiO 2 surface layers were characterised 62 by scan-free grazing-exit soft XRF spectrometry . A CMOS camera recorded simultaneously both the angle-dependent signals over a broad range of angles and an energy-dispersive spectrum at each angle.…”