Multi‐angle spectroscopic extreme ultraviolet reflectometry for analysis of thin films and interfaces

Abstract

Modern nanotechnology is constantly raising demands to quality and purity of thin films and interlayer interfaces. As thicknesses of employed layers decrease to single nanometers, traditional characterization tools are no longer able to satisfy throughput, precision or non-destructibility requirements. Extreme ultraviolet (EUV) and soft X-ray reflectometry has not only demonstrated the ability to detect sub-nm thickness variations but also was shown to be very sensitive to chemical composition changes. Since the laboratory radiation sources in this wavelength range often emit in a relatively broad spectral range, a spectroscopic EUV reflectometry has been developed with the added benefit of a rapid measuring time on the order of milliseconds to seconds. In this paper, the extension of the method to multi-angle measurements will be presented. It allows to reduce a number of fit parameters in the analysis model, making the method suitable for complex samples of unknown composition. First experimental examples for Si-based layer systems measured under grazing incidence angles between 2° and 15° will be demonstrated and discussed

Spatially Resolved Spectroscopic Extreme Ultraviolet Reflectometry for Laboratory Applications

“…20 Depending on the source working gas, different spectral ranges are accessible. The utilized krypton/xenon mixture, 4 for instance, provides broadband EUV emission within 9.5-17 nm. A general view and the operation scheme of the tool can be found in Figure 1.…”

“…It offers high chemical sensitivity due to the strong interaction of EUV radiation with matter, being able to resolve ultra-thin layers with sub-nanometer thickness variations. 4 A coupling of the method with X-ray reflectometry is especially prominent for the characterization of complex layered systems, benefiting from the strong sides of both techniques. 5 The short wavelength of EUV is advantageous for achieving a spatial resolution higher than visible light * Author to whom correspondence should be addressed.…”

Employing partially coherent, compact gas-discharge sources for coherent diffractive imaging with extreme ultraviolet light

“…This enables even small scale laboratories and universities to obtain CDI with EUV light. Apart from CDI, DPP-EUV sources were already successfully employed for lithography [10][11][12] ,spectroscopy 13,14 , reflectometry 15 , scatterometry and microscopy 16-18 . aft In this article, we have demonstrated CDI of a complex valued object at 17.3 nm wavelength (Oxygen VI 3d-2p spectral line). The photon flux of the source was estimated to be larger than 13 10 3⋅…”

Ptychographic imaging with partially coherent plasma EUV sources

“…Initially designed for projection EUV lithography, EUV light from the discharge plasma is also used nowadays for metrology purposes, for example, reflectometry [5][6][7], scatterometry [8], photoemission electron microscopy [9], and magnetic polarization spectroscopy [4]. Furthermore, the current applications in nanostructuring using discharge EUV sources are focused on laboratorysize interference lithography [10] as well as resist and optics defectivity studies [11].…”