Non-contact XUV metrology of Ru/B4C multilayer optics by means of Hartmann wavefront analysis.

Short-wavelength imaging, spectroscopy, and lithography scale down the characteristic length-scale to nanometers. This poses tight constraints on the optics finishing tolerances, which is often difficult to characterize. Indeed, even a tiny surface defect degrades the reflectivity and spatial projection of such optics. In this study, we demonstrate experimentally that a Hartmann wavefront sensor for extreme ultraviolet (XUV) wavelengths is an effective non-contact analytical method for inspecting the surface of multilayer optics. The experiment was carried out in a tabletop laboratory using a high-order harmonic generation as an XUV source. The wavefront sensor was used to measure the wavefront errors after the reflection of the XUV beam on a spherical Ru/B4C multilayer mirror, scanning a large surface of approximately 40 mm in diameter. The results showed that the technique detects the aberrations in the nanometer range.

[1]  H. Quiney,et al.  An extreme ultraviolet interferometer using high order harmonic generation , 2014 .

[2]  Atsushi Momose,et al.  Wavefront measurement for a hard-X-ray nanobeam using single-grating interferometry. , 2012, Optics express.

[3]  Kenneth A. Goldberg,et al.  Extreme ultraviolet mask substrate surface roughness effects on lithographic patterning , 2010 .

[4]  Extreme Ultraviolet Stokesmeter for Pulsed Magneto-Optics , 2015 .

[5]  Jun Feng,et al.  X-ray metrology and performance of a 45-cm long x-ray deformable mirror. , 2016, The Review of scientific instruments.

[6]  S. Hädrich,et al.  Lensless diffractive imaging using tabletop coherent high-harmonic soft-X-ray beams. , 2007, Physical review letters.

[7]  Timm Weitkamp,et al.  X-ray wavefront analysis and optics characterization with a grating interferometer , 2005 .

[8]  Frank Barkusky,et al.  Near-edge x-ray absorption fine structure measurements using a laboratory-scale XUV source , 2008 .

[9]  A. Mancuso,et al.  Single-shot determination of focused FEL wave fields using iterative phase retrieval. , 2017, Optics express.

[10]  J. Martynczuk,et al.  Actinic damage of Y/Mo multilayer optics in a table-top plasma-driven x-ray laser. , 2014, Applied optics.

[11]  Davide Bleiner,et al.  He-doped pseudospark as a home-lab XUV source beyond the beamtime bottleneck , 2017 .

[12]  G. E. Sommargren,et al.  Phase Shifting Diffraction Interferometry for Measuring Extreme Ultraviolet Optics , 1996, Extreme Ultraviolet Lithography (TOPS).

[13]  Xavier Levecq,et al.  Hartmann wave-front measurement at 13.4 nm with lambdaEUV/120 accuracy. , 2003, Optics letters.

[14]  Anton Barty,et al.  Actinic inspection of multilayer defects on EUV masks , 2005, SPIE Advanced Lithography.

[15]  H.T. Kim,et al.  High brightness harmonic generation at 13 nm using self-guided and chirped femtosecond laser pulses , 2004 .

[16]  Przemyslaw Wachulak,et al.  Single-shot extreme ultraviolet laser imaging of nanostructures with wavelength resolution. , 2008, Optics letters.

[17]  Mabel Ruiz-Lopez,et al.  Implementing the plasma-lasing potential for tabletop nano-imaging , 2014 .

[18]  Regina Soufli,et al.  Multilayer optics for an extreme-ultraviolet lithography tool with 70-nm resolution , 2001, SPIE Advanced Lithography.

[19]  Davide Bleiner,et al.  Extreme ultraviolet lasers: principles and potential for next-generation lithography , 2012 .

[20]  Yuya Yamaguchi,et al.  Imaging Performance Improvement of an Extreme Ultraviolet Microscope , 2010 .

[21]  U. Schubert,et al.  Ion-, photoelectron- and laser-assisted analytical investigation of nano-structured mixed HfO2-SiO2 and ZrO2-SiO2 thin films , 2005 .

[22]  H. Ohashi,et al.  Stitching interferometry for ellipsoidal x-ray mirrors. , 2016, The Review of scientific instruments.

[23]  J. Y. Wang,et al.  Wave-front interpretation with Zernike polynomials. , 1980, Applied optics.

[24]  Mark R. Kozlowski,et al.  In-situ atomic-force microscopy of laser-conditioned and laser-damaged HfO2/SiO2 dielectric mirror coatings , 1992, Laser Damage.

[25]  Masanobu Hasegawa,et al.  Wavefront measurement interferometry at the operational wavelength of extreme-ultraviolet lithography. , 2007, Applied optics.

[26]  Mark R. Kozlowski,et al.  Surface morphology of As-deposited and laser-damaged dielectric mirror coatings studied in-situ by atomic force microscopy , 1992, Optics & Photonics.

[27]  F Pedaci,et al.  Microscopy of extreme ultraviolet lithography masks with 13.2 nm tabletop laser illumination. , 2009, Optics letters.

[28]  Y. Ichihara.  Evolution of wavefront metrology enabling development of high-resolution optical systems , 2014 .

[29]  Xavier Levecq,et al.  Optimization of the wave front of high order harmonics , 2008 .

[30]  Hidekazu Mimura,et al.  At-wavelength figure metrology of hard x-ray focusing mirrors , 2006 .

[31]  Jenah Harris-Jones,et al.  Applications of advanced metrology techniques for the characterization of extreme ultraviolet mask blank defects , 2013 .

[32]  G. Paulus,et al.  An extreme ultraviolet Michelson interferometer for experiments at free-electron lasers. , 2013, The Review of scientific instruments.