Grazing incidence-X-ray fluorescence spectrometry for the compositional analysis of nanometer-thin high-κ dielectric HfO2 layers

In future microelectronic devices, SiO₂ as a gate dielectric material will be replaced by materials with a higher dielectric constant. One such candidate material is HfO₂. Thin layers are typically deposited from ligand-containing precursors in chemical vapor deposition (CVD) processes. In the atomic layer deposition (ALD) of HfO₂, these precursors are often HfCl₄ and H₂O. Obviously, the material properties of the deposited films will be affected by residual ligands from the precursors. In this paper, we evaluate the use of grazing incidence- and total reflection-X-ray fluorescence spectrometry (GI-XRF and TXRF) for Cl trace analysis in nanometer-thin HfO₂ films deposited using ALD. First, the results from different X-ray analysis approaches for the determination of Hf coverage are compared with the results from Rutherford backscattering spectrometry (RBS). Next, we discuss the selection of an appropriate X-ray excitation source for the analysis of traces within the high-κ layers. Finally, we combine both in a study on the accuracy of Cl determinations in HfO₂ layers. 2005