Grazing Incidence-X-ray Fluorescence Spectrometry for the Compositional Analysis of Nanometer-Thin High-κDielectric HfO2 Layers

Abstract

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.

Automated nanoliter solution deposition for total reflection X-ray fluorescence analysis of semiconductor samples

“…As the TXRF is being used to characterize the new films being introduced into the semiconductor process line and to monitor for cross contamination from these new materials [14][15][16][17][18], nanoliter depositions can be used with TXRF to improve upon the characterization process. Fig.…”

How Trace Analytical Techniques Contribute to the Research and Development of Ge and III/V Semiconductor Devices

“…conventional TXRF, is preferable however in terms of simplicity and speed. Validation studies with RBS as a reference demonstrated that for dense layers on lighter substrates, such as HfO 2 on Si substrates, the TXRF approach is limited to layers <1 nm due to saturation effects, as reported before (9). In this study we extended the investigation for light layers on denser substrates, such as a passivation layer of Si on Ge.…”

Trends in total reflection X-ray fluorescence spectrometry for metallic contamination control in semiconductor nanotechnology

“…Whereas before only Si and SiO 2 wafers were measured, now a whole range of materials as wafers or layers have been reported in research and development applications: silicon nitride [102,103], siliconon-insulator (SOI) [104], Ge [105,106], GaAs [107,108], HfO 2 [109][110][111], Al 2 O 3 [110,111], Ta 2 O 5 [112], polymer layers [113] and other unpublished materials. Both procedures for Direct-TXRF and VPD-DC-TXRF have been reported.…”

“…A first characteristic of interest for layered materials is in the coverage of the material constituent on the bulk substrate. TXRF has been applied to characterize deposition processes of for example gate dielectrics [109][110][111]114], with a clear advantage of accessibility, user friendliness and related learning speed compared to established techniques such as Rutherford backscattering spectrometry (RBS). Fig.…”

“…Besides coverage analysis, TXRF or GI-XRF is at the same as well useful to analyze impurities in the layers. The accuracy of the method is however strongly influence by the distribution of the impurities in the layer, as demonstrated for residual Cl analysis in HfO 2 layers deposited in an atomic layer deposition process [109]. Other applications are in the characterization of implants in Si substrates in different methods, going from direct analysis over combination with chemical etching or physical sputtering and grazing incidence methods [115][116][117][118][119][120][121].…”