Characterization of High-k Nanolayers by Grazing Incidence X-ray Spectrometry

Abstract

The accurate characterization of nanolayered systems is an essential topic for today’s developments in many fields of material research. Thin high-k layers and gate stacks are technologically required for the design of current and future electronic devices and can be deposited, e.g., by Atomic Layer Deposition (ALD). However, the metrological challenges to characterize such systems demand further development of analytical techniques. Reference-free Grazing Incidence X-ray Fluorescence (GIXRF) based on synchrotron radiation can significantly contribute to the characterization of such nanolayered systems. GIXRF takes advantage of the incident angle dependence of XRF, in particular below the substrate’s critical angle where changes in the X-ray Standing Wave field (XSW) intensity influence the angular intensity profile. The reliable modeling of the XSW in conjunction with the radiometrically calibrated instrumentation at the PTB allows for reference-free, fundamental parameter-based quantitative analysis. This approach is very well suited for the characterization of nanoscaled materials, especially when no reference samples with sufficient quality are available. The capabilities of this method are demonstrated by means of two systems for transistor gate stacks, i.e., Al2O3 high-k layers grown on Si or Si/SiO2 and Sc2O3 layers on InGaAs/InP substrates.

Reference-free grazing incidence x-ray fluorescence and reflectometry as a methodology for independent validation of x-ray reflectometry on ultrathin layer stacks and a depth-dependent characterization

“…A direct and traceable quantification of the mass depositions can then be performed as presented in ref. 15 using Sherman's equation. The necessary instrumental parameters, e.g.…”

“…In this respect, we derived the total elemental mass depositions using our reference-free quantification scheme 11,12,15,36 to set-up a hybrid reference-free GIXRF-XRR modeling. It uses the information about the elemental mass depositions, which can be used to reduce the degrees of freedom within the modeling.…”

Interaction of nanoparticle properties and X-ray analytical techniques

“…In Figure 2, a schematic drawing of the experimental setup used for the reference-free XRF and GIXRF is shown. The combined method of GIXRF measurement and the calculation of the intensity distribution of the XSW field is described in detail elsewhere [41] and will just be summarized here. GIXRF measurements are basically a variation of the incident angle around the critical angle of total external reflection while the element-specific fluorescence radiation is detected.…”

2015 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry and their applications

“…Muller et al 391 characterised high-k nanolayers using GI-XRF spectrometry. Muller et al 391 characterised high-k nanolayers using GI-XRF spectrometry.…”