Table-top EUV/Soft X-ray Source and Wavefront Measurements at Short Wavelengths

Transcription

1 Table-top EUV/Soft X-ray Source and Wavefront Measurements at Short Wavelengths K. Mann J.O. Dette, F. Kühl, U. Leinhos, M. Lübbecke, T. Mey, M. Müller, M. Stubenvoll, J. Sudradjat, B. Schäfer Laser-Laboratorium Göttingen e.v. Hans-Adolf-Krebs Weg 1 D Göttingen Laser- Laboratorium Göttingen e.v.

2 Dept. Optics / Short Wavelengths Optics test ( nm) (Long term) degradation (10 9 pulses) Non-linear processes LIDT Absorption / Scatter losses Wavefront deformation Beam propagation Wavefront coherence M² EUV/XUV technology Source & Optics Metrology Material interaction 2

3 Laser plasma source for extreme UV and soft x-ray radiation laser ~ 300µm pulsed Xenon gas jet XUV: =1 10nm EUV: = 10 20nm Univ. Prag Univ. Göttingen Max-Planck Inst. compact low debris long-term stable versatile

4 Reflectivity LLG-Activities Based on LPP Source Direct structuring EUV reflectometry Sample angle =2.88nm NEXAFS spectroscopy Soft x-ray microscopy 4

5 Ablation / damage EUV Schwarzschild objective (Mo/Si): ~ 13,5 nm Damage thresholds of mirrors / substrates single-pulse damage F. Barkusky, K. Mann et al., Optics Express 18, 4347 (2010) 5

6 EUV/XUV plasma source T. Salditt Univ. Göttingen Isolated Nitrogen = 2.88nm Peak brillance: 6*10 17 [Ph./(s mrad 2 mm 2 0,1%BW)] = 2.88nm

7 Absorption length (µm) NEXAFS Spectroscopy in the water window : = Near-edge x-ray absorption fine-structure Excitation of unoccupied molecular orbitals Fingerprint of molecules surface-sensitive chemical analytics Accessable absorption edges Spectrum of Krypton plasma 10 H 2 O 1 C 0,1 Ti N Ca O: 2,28 nm Ti: 2,73 nm N: 3,0 nm Ca: 3,58 nm C: 4,36 nm 2,0 2,5 3,0 3,5 4,0 4,5 5,0 Wavelength (nm) B, C, N, O, F, S, Ca, Ti, Mn, Fe

8 Intensity [CCD-Counts] Transmission Optical density [a.u.] Table-top NEXAFS Spectrometer = 1 7nm, 10 20nm Laser polychromatic concept ( single-shot ) transmission of thin samples Synchrotron (J. Stöhr) Source sample spectrometer polyimide sample (d=200nm): Transmission Carbon (CXRO) without sample with Polyimid (d=200nm) 1,0 0,8 0,6 0,4 0,2 2,0 1,5 1,0 0,5 * C=C * C-N * C=C * C=O * C=O Polyimide 60 laser pulses 0 0, Photonenenergy [ev] 0, Photon energy [ev] Carbon K-edge C. Peth, K. Mann et al., J. Phys. D 41 (2008)

9 Compact NEXAFS spectrometer = 1 7nm 10 20nm pump-probe exp. measurement in ambient air

10 Optical density Optical Thickness [a.u.] NEXAFS spectroscopy on thin films Lipid membranes (carbon K-edge) (T. Salditt) Wavelength [nm] 4,4 4,3 4,2 4,1 4 3,9 * C=C DOPC DMPC DOPS Photon energy (ev) PCMO (Perovskite-type manganate) Pr 1-x Ca x MnO 3 (S. Techert) 2,0 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 Ca L 2,3 N K NEXAFS-Spectrum PCMO O K Mn L 2,3 Pr M 4,5 1, Photon-Energy (ev) : Pr, Ca : O : Mn Every element visible (single shots) Pump-probe experiments phase transitions E. Novakova, C. Peth, K. Mann, T. Salditt et al.: Biointerphases, 3 (2008) FB44 P. Grossmann, S. Techert, C. Jooss, K. Mann et al.: Rev. Sci. Instr. 2012

11 NEXAFS at Fe L 2,3 edge Example: Prussian Blue Carbon K edge Iron L 2,3 edge Photon energy ~ 720eV 300 laser pulses

12 Improvements (1): Power density: ns ps laser Single pulse spectra: Single Single pulse pulse XUV XUV spectra spectra Single-Pulse - Max. Laserpulse-Energy - Al filtered Nitrogen Oxygen Neon N (Z = 7) O (Z = 8) Ne (Z = 10) 150ps 380mJ ns 450mJ Photon energy (ev) Photon energy (ev) Photon energy (ev) Ar (Z = 18) Kr (Z = 36) Xe (Z = 54) Photon energy (ev) Photon energy (ev) Single pulse XUV spectra Photon energy (ev) Peak brillance Argon of isolated N = 2.88nm: Krypton Xenon 6*10 17 (ns laser) 1.2*10 20 Ph./(s mrad 2 mm 2 0,1%BW) (ps laser)

13 Simulation of spectra: Ar ns measured ps measured Calculation with MHD code PrismSPECT simulated simulated ns laser ps laser electron temperature [ev] electron density [10 19 e/cm³] M. Müller, K. Mann et al.: Opt. Express 21 (2013)

14 Improvements (2): Plasma generation with barrel shock Schlieren image Nitrogen 10 bar Helium 170 mbar Nitrogen 10 bar Vacuum ~10-3 mbar ~10x brilliance = 2.88 nm 500 µm 500 µm T. Mey, M. Rein, K. Mann, New J. Phys. 14 (2012)

15 Improvements (3): Focusing optics for x-ray plasma Nitrogen plasma, = 2.88nm (monochromatic) grazing incidence ellipsoidal mirror focus dia. ~ 500µm laser plasma ellipsoidal mirror caustic measurement

16 Ablation of =2.88nm FWHM 500 µm Kr plasma (3 6nm): ~ 100mJ/cm² 5000 N 2 15 bar, 3 min ultrasonic bath focal spot of elliptical mirror: ~ nm 8.5*10 9 photons/pulse

17 Improvements (3): Focusing optics for x-ray plasma Nitrogen plasma, = 2.88nm (monochromatic) grazing incidence ellipsoidal mirror focus dia. ~ 500µm laser plasma ellipsoidal mirror caustic measurement Optics adjustment: time-consuming

18 Wavefront measurements Hartmann-Shack sensor: wavefront: directional distribution intensity distribution Wavefront w(x,y) = surface Poynting-Vektor S(x,y) (ISO ) 18

19 Beam characterization of FLASH Experimental setup at BL2 = nm Hartmann plate Adjustment of beam line optics by online wavefront monitoring 0.5 Yaw [mrad] w rms =15.5nm w rms =3.5nm w rms =2.6nm w rms =2.6nm w rms =5.9nm 0.0 w rms =13nm [1] B. Flöter et al, Beam parameters of FLASH beamline BL1 from Hartmann wavefront measurements, Nucl. Instrum. Meth. A 635 (2011) Pitch [mrad]

20 Beam characterization of FLASH Experimental setup at BL2 = nm Hartmann plate before adjustment after adjustment Wavefront w rms ~ 10nm w rms ~ 2.5nm ~ /10 Intensity [2] B. Flöter et al, EUV Hartmann sensor for wavefront measurements at the Free-electron LASer in Hamburg, New J. Phys. 12 (2010)

21 Beam parameters from Hartmann data FLASH =7nm Beam profiles and wavefronts of single pulses (no focusing mirror) Beam propagation parameters X Y w pv [nm] 5.3 ± 0.69 w rms [nm] 0.67 ± 0.09 Beam propagation parameter M ± 0.08 ( ) Beam propagation parameter M 2 i 1.23 ± ± 0.1 ( ) Beam width d [mm] 6 ± ± 0.1 Waist position z 0,i [m] ± ± 1.4 Rayleigh length z R [mm] 3760 ± ± 731 Waist diameter d 0,i [µm] 2 nd moment 200 ± ± 25 ( ) Divergence [µrad] 55 ± 2 44 ± 2 ( )

22 Beam characterization at / = 32nm Focal spot size: Computed PMMA imprint 10x10µm² Active KB System Wavefront sensor

23 Summary: Laser plasma EUV / soft x-ray source Clean, stable, compact =1 20nm, ns ps pulses reflectometry, ablation studies, NEXAFS / EXAFS for chemical analysis spectro-microscopy Hartmann wavefront sensor (EUV / soft x-rays) real-time alignment of optics beam propagation for single pulses Characterization of partially coherent radiation Wigner distribution

24 Thank You! Coworkers: Dr. B. Schäfer Dr. U. Leinhos J.O. Dette W. Hüttner F. Kühl M. Lübbecke T. Mey M. Müller G. Steinert J. Sudradjat M. Stubenvoll

25 CCD-Counts XUV peak brillance of laser plasma source N VI 1s 2-1s2p Stickstoff - Einzelpuls - Al gefiltert N VII 1s 2-1s2p N VI 1s 2-1s3p N VI 1s 2-1s4p N VI 1s 2-1s5p N VI 1s 2-1s6p N VII 1s 2-1s3p N VII 1s 2-1s4p N VII 1s 2-1s5p Photonenenergie (ev) Isolated N VI 1s 2-1s2p nm (Ti filtered) Peak brillance [Photons/(s mrad 2 mm 2 0,1%BW)] ns laser: 6*10 17 (LLG, T. Wilhein) ps laser: 1,2*10 20 (LLG) Brightness (ps): ~10 14 photons/(pulse x sr)

26 Comprehensive beam characterization Wigner distribution = Fourier transform of Mutual Coherence Function Caustic of FLASH: Phosphor coated screen Long working distance microscope Translation stage CCD camera Intensity distribution Beam diameter

27 Determination of Wigner distribution function mapping measured data into 4D Wigner Fourier space FFT Wigner distribution function h x x, u = h x, y, u, v dydv h y y, v = h x, y, u, v dxdu Reconstruction of beam profiles B. Schäfer, T. Mey, K. Mann, K. Tiedtke et al, Nucl. Inst. Meth comprehensive beam characterization beam parameters coherence function mode content wavefront angular characteristics

28 Spectrum of electromagnetic radiation EUV Lithography 13.5 nm water window Wavelength 1µm 100nm 10nm 1nm 0.1nm Soft x-rays Extreme UV Hard x-rays 1eV 10eV High 100eV 1keV 10keV Excimer lasers Harmonics Free electron lasers Photon energy

29 Kompaktes Labor-Röntgenmikroskop Gepulstes Hochdruck-Gastarget A) monochromatische =2,88nm (N 2 + Ti-Filter) B) Bichromatisches Konzept zur elementspezifischen Mikroskopie um die Ca-Kante ( =3,58 nm) Spektro-Mikroskopie

30 NEXAFS measurements at athmospheric pressure Polyimide: 2 4mm

31 Improvements (2): Plasma generation with barrel shock Schlieren image Nitrogen 10 bar Helium 170 mbar Nitrogen 10 bar Vacuum ~10-3 mbar 500 µm 500 µm 31

32 Improvements (3): Barrel shock Nitrogen 10bar Schlieren images: ambient pressure: 1 bar 10-3 mbar 500µm 32

33 Beam characterization: Hartmann-Shack wavefront sensor Spot distribution - Beam profile Propagation analysis - Wavefront Zernike Analysis: Beam parameters: M x 2 x x x x 2 B.Schäfer, K. Mann, Rev. Sci. Instr. 77, (2006) 33

34 EXAFS: Cl L-edge of NaCl EXAFS structures 200nm NaCl film L-edge of Cl (EUV range) Bond lengths: Excellent agreement with Synchrotron data R i E i C E Streu

35 Results and discussion I - Overview 17 November 2013 Emission properties of ns and ps laser-induced soft x-ray sources 35

36 Results and discussion III different pulse energies N 2 Kr The higher emission intensity of the ps plasma and shift to shorter wavelengths (considering the same pulse energy of ns and ps laser) is attributed to the higher electron density and higher electron temperature, respectively. 17 November 2013 Emission properties of ns and ps laser-induced soft x-ray sources 36

37 Results and discussion VI Parameter ns laser ps laser Wavelength (λ) 1064 nm 1064 nm Pulse duration (τ) (FWHM) 7 ns 0.17 ns Laser pulse energy (Q) 450 mj 380 mj Diameter of focal spot 30 µm 20 µm Maximum power density 2.2 x W/cm² 1.7 x W/cm² Plasma size 470 µm x 190 µm 310 µm x 150 µm Brightness 5 x photons/(pulse x sr) 8 x photons/(pulse x sr) Peak 2.88 nm 1 x photons/(s x mrad² x mm²) 4 x photons/(s x mrad² x mm²) 37

38 Soft x-ray microscopy II caustic measurement FWHM 500 µm z [mm] 38

39 depth [nm] Soft x-ray microscopy III Ablation of 2.88nm EUV energy density 13.5 nm fragmentation ablation dose [mj/cm² x number of pulses] 5000 pulses, N 15 bar, 3 min ultrasonic bath energy density between 0.3 mj/cm² nm in the focal spot of the elliptical mirror 8.5*10 9 photons/pulse 17 November 2013 Applications of ns and ps laser-induced soft x-ray sources 39

40 Soft x-ray microscopy IV 2.3*10 12 photons/(sr*pulse ) 1.8*10 11 photons/(sr*pulse ) R 8% 17 November 2013 Applications of ns and ps laser-induced soft x-ray sources 40

41 Caustic of HHG Source 25. Harmonic ( =32nm) 90.0 mm d 0y 2 d 0y z 0y z Ry x y Waist diameter d µm µm Waist position z mm mm Rayleigh length z R 10.7 mm 30.1 mm Beam propagation factor M² Aberrations!

42 Real-time wavefront measurement 25. Harmonic ( =32nm) Yaw angle Pitch angle! 42

43 Spatial coherence: Young s experiment: 2a x + s/2 interference of elementary waves x s/2 s Contrast of fringes local degree of coherence γ x, s : d 43

44 Caustic of Free Electron Laser FLASH / DESY Beam parameter Waist position z 0x / z 0y [mm] Waist diameter d 0x / d 0y [µm] Rayleigh length z Rx / z Ry [mm] Beam propagation factor M² x / M² y Value / / / / 13 d 0x z 0x 2 d 0x z Rx coherence??? 44

45 Wigner distribution y h = Fourier transform of Mutual Coherence Function: v z x Wigner distribution h x, u = 1 2π 2 mutual coherence function Γ x, s e iu s d 2 s spatial coordinate x = x y angular coordinate u = u v Interpretation: radiance at position x in direction of u h = W m² sr M. J. Bastiaans, 1986, Opt. Acta