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.
Highlights
The development and fabrication of nanolayered gate stacks for nanoelectronic devices requires well-controlled deposition methods for high-k materials on various substrate materials and/or on substrates with different chemical character
The results presented in this study demonstrate the capability of the reference-free Grazing Incidence X-ray Fluorescence (GIXRF)
In addition to its fundamental importance, the reference-free quantification method is of high relevance in process technology and layer engineering, where quantification of various materials is performed on a routine basis relying on calibration standards
Summary
The development and fabrication of nanolayered gate stacks for nanoelectronic devices requires well-controlled deposition methods for high-k materials on various substrate materials and/or on substrates with different chemical character. To overcome this lack of appropriate nanoscale reference materials [11,12] one can use reference-free (GI)XRF [13] In this method, radiometrically calibrated instrumentation is used and no pre-calibration by calibration standards is required to obtain quantitative information. Radiometrically calibrated instrumentation is used and no pre-calibration by calibration standards is required to obtain quantitative information This enables a high flexibility of the technique in view of accessible materials, compositions and layer structures. In order to demonstrate the capability of reference-free GIXRF a set of Al2O3 high-k layers grown on Si or Si/SiO2 substrates was studied. These systems were chosen for their known differences in. We have investigated a rather unconventional material system, i.e., a Sc2O3 layer grown on InGaAs/InP substrates, to exemplify the high suitability of reference-free GIXRF for various material combinations
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