Abstract
We present a general method for designing XUV aperiodic multilayer mirrors that can mimic a given target spectrum, specifically, the spectral transmission of an XUV optical system. The method is based on minimizing a merit function and using fidelity parameters that quantify the matching of the multilayer reflectivity spectrum with that of the target spectrum. To assess the feasibility of fabricating such a system, we show how to reduce the layer-to-layer thickness variations throughout the aperiodic layer stack. We demonstrate the design method using an example of an EUV optical system composed of 12 identical Mo/Si multilayer mirrors having a reflectivity peak at 13.5 nm. We found that the target spectrum can be mimicked with high fidelity either with a single reflection at an aperiodic multilayer mirror combined with standard absorbing filters or, if required, with two subsequent reflections at a mimic mirror. These examples demonstrate the applicability for metrology at XUV sources, including spectrally proper source imaging. Because our approach is of general applicability, the process can be used to mimic any other narrowband, single-peaked target spectrum in the XUV region.
Highlights
The development of sources for the XUV wavelength band, typically from few tens to few tenths of a nanometer, is important for a wide range of scientific and industrial applications, such as EUV lithography [1], photoelectron spectroscopy [2], high-resolution microscopy [3], and surface analysis [4]
Referring to EUV lithography (EUVL), we demonstrate the design of aperiodic multilayer mirrors that mimic the transmission of a 13.5-nm optical system of multiple Mo/Si mirrors
We presented a general method for designing mimic XUV optical systems able to reproduce the spectral reflectivity peak of a given transmission spectrum by combining aperiodic multilayers and free-standing absorbing layers
Summary
The development of sources for the XUV wavelength band, typically from few tens to few tenths of a nanometer, is important for a wide range of scientific and industrial applications, such as EUV lithography [1], photoelectron spectroscopy [2], high-resolution microscopy [3], and surface analysis [4]. This development requires complex optical systems comprising of reflective multilayer mirrors for imaging, as well as dedicated XUV optical components for on-line monitoring, source metrology and standardized characterization. While the main body of this paper is dedicated to the theoretical approach to the design of such a mimic mirror, considerations related to experimental and fabrication issues are made in Appendix A
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
