Grazing-incidence X-ray fluorescence analysis of thin chalcogenide materials deposited on Bragg mirrors

E. Nolot (1) , W. Pessoa (1) , S. Torrengo (1) , Y. Mazel (1) , M. Bernard (1) , P. Gergaud (1) , Yves Ménesguen (2) , Marie-Christine Lépy (2) , D. Eichert (3)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
2 LNHB (CEA, LIST) - Laboratoire National Henri Becquerel (CEA, LIST)
3 Elettra Sincrotrone Trieste

Advanced chalcogenide materials are key for state-of-the art memories, energy harvesting materials and photonics. The properties of thin chalcogenide layers are highly driven by their chemical composition, chemical depth-profiles and surface/interface effects. The combination of Grazing-Incidence X-ray Fluorescence (GIXRF) and X-ray Reflectometry (XRR) techniques allows for non-destructive access to such information, in the lab or at dedicated beamlines. However, the accuracy of the GIXRF-deduced composition slightly degrades with depth, as the enhancement of the XRF signal by the X-ray Standing Wave (XSW) field is usually limited to the first nanometers at the surface of the probed sample. In this paper, we suggest the use of (Mo/Si)*N Bragg mirrors, rather than bare silicon substrates for thin chalcogenide deposition, to improve the sensitivity of GIXRF/XRR analysis to small process-driven modifications. The aim of such multilayered substrates is to maintain high values of X-ray reflected intensity even at angles significantly higher than the critical angle, therefore generating an XSW-induced enhancement of the XRF signal not only at the surface but also in the depth of the layer of interest. The simulation of GIXRF-XRR data, collected at SOLEIL Metrology beamline and in the lab on Rigaku SmartLab diffractometer, on arsenic-free Ovonic Threshold Switch materials (Ge, Se, Sb) for advanced Phase Change memory (PCRAM) applications illustrates the interest of this approach, which is fully-compatible with numbers of PCRAM materials elaborated with low-temperature physical vapor deposition process.

Mots clés: ionizing radiation; metrology; X-ray fluorescence; X-ray Reflectometry; chalcogenides; combined analysis; phase-change memory; thin film; depth-profile; surface-interface effect; Bragg mirror; multilayered substrate; SOLEIL; Grazing-incidence X-ray fluorescence; chemical vapor deposition (CVD)

Domaines: Physique [physics]

E. Nolot, W. Pessoa, S. Torrengo, Y. Mazel, M. Bernard, et al.. Grazing-incidence X-ray fluorescence analysis of thin chalcogenide materials deposited on Bragg mirrors. Spectrochimica Acta Part B: Atomic Spectroscopy, 2020, 168, pp.105864. ⟨10.1016/j.sab.2020.105864⟩. ⟨hal-03490712⟩