This MINOS labex research project will be supported by the strong collaboration between the CEA-LETI and LMGP teams. The main objective of this research project is to develop and share X-ray fluorescence quantitative elemental analysis methodologies of ultra-thin inorganic materials to accelerate the development of advanced material processes at Leti and LMGP. The Following contributions will be carefully and extensively investigated: instrumental (from TXRF and GIXRF to XRF, using EDXRF and WDXRF detection and state of the art Tools with multiple anodes), modeling and calibration strategies. XRF methodologies will be specifically dedicated to: i/ ultrathin (< 0.5 nm) mono-element lanthanum and aluminum layers, which will be integrated into the 10 nm CMOS gate stack; ii/ the thin layers (5-50 nm) of perovskite structure oxides (lanthanum nickelate, La2NiO4) and fluorite (zirconia stabilized with yttrium oxide and cerium oxide doped with gadolinium) developed by the LMGP for memory applications (OxRAM); iii/ ultra-thin layers of lamellar sulphides synthesized and studied at LMGP (GaxS, TixS) and at Leti (2D materials).