At wavelength characterization of EUV and soft X-ray gratings F. Scholze, A, Haase, C. Laubis, V. Soltwisch, J. Wernecke, M. Krumrey Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587 Berlin, Germany M. Burkhardt, A. Gatto Carl Zeiss Jena GmbH, Carl-Zeiss-Promenade 10, 07745 Jena, Germany
Outline PTB s EUV radiometry beamline optical characterization of a blazed grating and performance in beamline Determination of profile parameters with GISAXS Scatter from bare and coated substrate Scatter from resist pattern Conclusions 2
PTB laboratories in Adlershof BESSY II 3
PTB laboratory at BESSY II EUV 1 plane grating monochromator SX700 3c deflected undispersed bending magnet 30 nm to 0.7 nm radiation, EUV irradiation test station 2a four-crystal monochromator 4a undispersed undulator radiation 0.7 nm to 0.1 nm Compton backscattering 2b X-ray pencil beam facility (XPBF), 4b plane grating monochromator (PGM) astrophysics optics characterization at undulator, 30 nm to 0.65 nm 3a undispersed bending magnet radiation 4c deflected undispersed undulator radiation 3b normal incidence monochromator EUVL metrology test station (source calibration) 4
Soft X-ray radiometry beamline at BESSY II Reflectometer halo-aperture Wavelength At 13 nm Radiant Power 0.5 µw Higher diffraction orders 0.06 % Diffuse scattered light 0.2 % 0.65 nm to 25 nm sample not in focus spot at sample > 0.5 mm low divergence (< 1 mrad vert., < 2 mrad hor.) beam halo suppressed by aperture 5
PTB s EUV Reflectometer 5 sr collector, 670 mm outer diameter Axis Range Q -30 to 95 Tilt -10 to 10 F 0 to 360 X -90 mm to 90 mm Y -10 mm to 300 mm Z -15 mm to 140 mm Det. X 0 mm to 120 mm Det. R 150 mm to 550 mm Det. Y 0 to 180 2q -5 to 190 Accuracy: 10 µm or 0.01 at MLS from August 2013 6
EUV-Ellipso-Scatterometer Linear polarization analyzer sample and detector stages of the Ellipsometer 8th-Workshop-Ellipsometry, Dresden, March 10.-12. 7
Measurement Scheme CCD Geometry for diffuse scatter measurements with CCD sensor 162 172 156 166 EUV reflectometer at SX700 until 2013 CCD mounted at 162 included angle EUV Ellipso-scatterometer from 2013 CCD mounted at 156 included angle 8th-Workshop-Ellipsometry, Dresden, March 10.-12. 8
Ruled, blazed grating Grating for EUV beamline at MLS, size 150 x 70 mm² 9
Blazed grating, diffraction efficiency diffraction efficiency for operation in PGM-mode with c ff = 2.5 1200 l/mm, blaze 4 => rather close to suspected values diffraction efficiency for operation in PGM-mode with c ff variable high contributions of higher diffraction orders for long wavelegths 10
GISAXS: Schematic q k f k i q q q x y z k k k 0 0 0 sinq cos cosq cos f i f sin sin f f f cos i Ewald sphere for gratings k 0 2 k i k f top view PM 11 19-22 11
Ruled, blazed grating, GISAXS Determination of blaze angle: 4.5(1) GISAXS at blazed grating 1200 l/mm E ph = 10 kev (log. intensity) Determination of Ru coating thickness: 46.3(7) nm Scholze, Kato, Wernecke, Krumrey, Proc. SPIE 8166, 81661P (2011) 12
Ruled, blazed grating, EUV scattering = 10 nm 2Q = 162 13
Ruled, blazed grating, EUV scattering fine structure of diffuse scatter 14
Grating performance in beamline 14.5 nm Measurement of spectral distribution with flat field spectrograph 25 nm 15
Holographic blazed grating Diffraction efficiency of holographic blazed gratings with different blaze angles (PGM-operation, c ff =2.5) => confirmation of optimal blaze angle 4 for this application samples mounted on holder 16
Holographic blazed grating * 1/5 => 20x improvement w.r.t. previous grating Diffuse scatter for holographic blazed grating => Si-L edge from beamline filter visible 17
Laminar Grating U. Zeitner et al., Proc SPIE 8450, 84502Z, 2012 diffraction efficiency of binary gratings with different CD (solid line 290 nm, long dashes 250 nm, dots 208 nm) and etch depth H benchmark: blazed grating 18
Laminar Grating: Influence of coating Diffuse scatter from a liminar grating etched into quartz extremely low diffuse scatter 10-7 with respect to 1 st. order x 0.01 => issue: sort out scatter from beamline Diffuse scatter for substrate(blue), coated (red) and no filter in beamline (green) 19
Laminar grating substrate bare substrate Ru coated Ru-coated substrate Observation of superstructure from e-beam writing on bare substrate and on coated grating Diffuse scatter for substrate(blue), coated (red) and no filter in beamline (green) 20
Holographic grating: Resist Investigation of resist images new set-up at PTB: 2Q = 156 diffuse scatter from two different illumination settings (B1 red and B2 blue) the setting B1 has much lower sattelites ghost from beamline grating substrate with resist 21
Conclusions diffraction efficiency not very sensitive to roughness diffuse scatter differs by orders of magnitude GISAXS enables direct measurement of line profile Diffuse scatter from bare substrate is representative for final grating Diffuse scatter from resist pattern reveals potential ghosts 22
Thank you for your attention Physikalisch-Technische Bundesanstalt Braunschweig und Berlin Abbestrasse 10-12 10587 Berlin Frank Scholze EUV Radiometry Telefon: 030 3481 7120 E-Mail: frank.scholze@ptb.de www.ptb.de