Zone Plate Microscopy

Transcription

1 Zone Plate Microscopy David Attwood University of California, Berkeley ( Zone Plate Microscopy and Applications, EE290F, 12 April 2007

2 Zone Plates for Soft X-Ray Image Formation Zone Plate Lens λ r r n r 2 r 1 D = 2r N f + nλ 2 Zone Plate Formulae r 2 = nλf + n n 2 λ 2 4 (9.9) λ = 2.5 nm, r = 25 nm N = 618 f θ D = 4N r (9.13) 63 µm f = 4N( r) 2 λ (9.14) 0.63 mm Soft X-Ray Microscope NA = λ 2 r (9.15) 0.05 µm λ Sample Res. = k 1 DOF = ± λ NA 1 2 λ (NA) 2 = 2k 1 r k 1 = 0.61 (σ = 0) k 1 = 0.4 (σ = 0.45) (9.50) 1.22 r = 30 nm 0.8 r = 19 nm 1 µm Zone Plate lens λ λ 1 N (9.52) 1/700 Soft X-ray CCD Ch09_F00modif_Oct04.ai

3 Two Common Soft X-Ray Microscopes Full-Field Microscope Scanning Microscope λ λ Sample Zone Plate lens Zone Plate lens Aperture (OSA) Sample scanning stage Soft X-ray CCD Detector Best spatial resolution Modest spectral resolution Shortest exposure time Bending magnet radiation Higher radiation dose Flexible sample environment (wet, cryo, labeled magnetic fields, electric fields, cement,...) Least radiation dose Next best spatial resolution Best spectral resolution Requires spatially coherent radiation Long exposure time Flexible sample environment Photoemission (restricted magnetic fields), fluorescence imaging Ch09_F21modif_Nov05.ai

4 A Fresnel Zone Plate Lens for X-Ray Microscopy E. Anderson, LBNL Univ. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007 Ch09_F01VG.ai

5 Diffraction from a Transmission Grating λ d (+1) θ (0) ( 1) ; (9.2) d θ λ θ (9.24) (50% absorbed) Ch09_F03VGrevApril04.ai

6 A Fresnel Zone Plate Lens λ (9.8) D = 2r N r n (9.9) r r 2 r 1 f + nλ 2 (9.10) f f 2 + r 2 = n f + nλ 2 2 rn 2 = nλf + n2 λ 2 4 θ Ch09_F05VG.ai

7 A Fresnel Zone Plate Lens λ D = 2r N Define the outer zone width for n N, (9.11) 2 r n r r 2 r 1 f f + nλ 2 θ but λ f = (9.12) (from 9.10) = D 2f (9.15) and from (9.12) above (9.13) (9.16) (9.14) Ch9_F05_Nov05.ai

8 A Fresnel Zone Plate Lens Used as a Diffractive Lens for Point to Point Imaging S p n p D q n (9.17) r q P (9.18) Ch09_F02_modif_VG.ai

9 Zone Plate Diffractive Focusing for Higher Orders ( 5) ZP ( 3) (m = 1) (9.19) λ f 5 5nλ + 2 f 3nλ f + nλ 2 (9.24) f m = 1 m r N 2 Nλ f 5 f 3 (m = 5) ( 3) ( 1) f OSA 1 f m = m f 1 Ch09_F08_Nov05.ai

10 Diffraction from a Fresnel Zone Plate λ η S(ξ,η) (9.45) D ξ (9.46) R θ r ρ 2 = ξ 2 + η 2 z y N 2 Airy pattern r P(x,y) x Focal plane intensity, I(θ)/Io N 2 2 N 2 2 2J 1 (kaθ) (kaθ) kaθ = kaθ Ch09_F11VG.ai

11 Resolving Two Point Sources (a) Ι (b) Rayleigh r null = 0.61λ/NA r null r r null = 0.61λ/NA Point sources are spatially coherent Mutually incoherent Intensities add Rayleigh criterion (26.5% dip) Conclusion: With spatially coherent illumination, objects are just resolvable when Res coh = 0.61 λ NA = 1.22 r Ch09_F14_April04.ai

12 Fresnel Zone Plate Lens for Diffractive Focusing of Spatially Coherent X-rays r λ x Spatial resolution: 1.2 r Opaque zones Coherent illumination (σ = 0) Res coh = NA = 0.61 λ NA λ 2 r Res coh = 1.22 r (σ = 0, see first slide) Ch09_FresnelZP_Apr07.ai

13 Partially Coherent Illumination Permits Improved Spatial Resolution by a Factor Approaching Two (a) k s k i d θ k s k i θ 2π d (b) k i d 2 2θ k s 2θ k i 2π (d/2) (c) θ illum. θ obj. d 2 NA illum. NA obj. sinθ illum. sinθ obj. σ = (for n = 1) Ch09_F19_Nov05.ai

14 Optical Transfer Properties with Varying Degrees of Partially Coherent Illumination Apparent transfer function 1.0 σ = 0 (coherent) σ = σ = 0.6 σ = (incoherent) Spatial frequency (NA/λ) NA illum. NA obj. sinθ illum. sinθ obj. σ = (for n = 1) Ch09_F10.2_Nov05.ai

15 Intensity Versus Position for a Sharp Edge Observed With Coherent and Partially Coherent Radiation Intensity 0.5 σ = σ = 1.5 σ = 1.0 σ = 0.9 σ = 0.8 σ = 0.6 σ = (edge) Distance (λ/2na) Courtesy of M. O Toole and A. Neureuther (UC Berkeley). Ch09_10.3.ai

16 Depth of Focus and Spectral Bandwidth λ (9.50) r (9.51) (9.52) z = f λ 2(NA) 2 z focal plane, z = f λ two depths of focus away, z = f (NA) 2 four depths of focus away, z = f 2λ (NA) 2 Ch09_F18_Nov05.ai

17 Why does DOF Scale as /NA2? High NA λ θ 0.6λ NA θ DOF/2 0.6λ NA DOF tanθ = 0.6λ/NA DOF/2 Low NA DOF = 1.2λ/NA tanθ λ θ DOF for small θ tanθ ~ sinθ = NA 1.2λ DOF NA 2 in the text, eq. 9.50: 1 λ DOF = ± 2 (NA) 2 Ch09_WhyDOFscale.ai

18 Test Pattern for Nanometer Soft X-ray Imaging E. Anderson, D. Olynick, B. Harteneck, E. Veklerov, LBNL Ch09_TestPattrn.ai

19 The XM-1 Soft X-Ray Microscope at the Advanced Light Source (ALS) 13 High spatial resolution (20 nm) Modest spectral resolution (E/ΔE ~700) Thick, hydrated samples (10 µm) Short exposure time (~1 second) Well engineered, pre-focused Mutually indexed visible and x-ray microscopes High throughput (hundreds of samples per day) Large image fields by tiling Easy access, user friendly Cryotomography E = kev λ = 0.7 nm - 5 nm ZP microscopy Apps2.ppt

20 High Resolution Zone-Plate Microscope XM-1 at the ALS Well engineered Sample indexing Tiling for larger field of view Pre-focused High sample throughput Illumination important Phase contrast ZP microscopy Apps2.ppt

21 Bending Magnet Photon Flux at the ALS Professor AST 210/EECS David 213 Attwood Univ. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007 ZP microscopy Apps2.ppt

22 XM-1 Parameters Micro Zone Plates Δr = 25 nm (15 nm), Δt = 70 nm (5%) (170 nm). N = 618, D = 63 µm, f = 650 µm, NA = 0.05 at 2.4 nm. Δr = 35 nm, Δt = 85 nm (8%). Condenser Zone Plate Δr = 55 nm (40 nm), Δt = 200 nm (22%). N = 41,000, D = 9 mm, f = 207 mm, NA = 2.4 nm. σ = 0.45 with Δr = 25 nm micro zone plate. Magnification M = 2400 to 3100; 24 µm CCD pixel Spectral Bandpass λ/δλ = 700, per pixel, 2 µm D field. λ/δλ = 500 with shaker, 10 µm D field. 8 nm at sample. CCD Camera Back thinned, soft x-ray sensitive x 1024 (2048 x 2048), 24 µm square pixels % efficient. Exposure Time 1-5 seconds, 10 3 photons/pixel, 8 µm diameter at sample ( ma, 2 x 2 binning, Δr = 25 nm) ZP microscopy Apps2.ppt

23 New Overlay Nanofabrication Technique for Narrower Outer Zones Δr = 15 nm Δt = 90 nm Overlay ~ 2 nm accuracy Courtesy of J.A. Liddle, E.H. Anderson, B. Harteneck and W. Chao, LBNL ZP microscopy Apps1.ppt

24 Multilayer Mirror Coatings Can Be Thinned and Used As Sub-20 nm Test Patterns SEM Micrograph of Cr/Si test pattern Δt Courtesy of W. Chao, UC Berkeley and CXRO/LBNL. High quality test patterns can be fabricated with sections as thin as 5 nm. ZP microscopy Apps1.ppt

25 Near Diffraction Limited Soft X-Ray Microscopy: 20 nm Spatial Resolution at 2.07 nm Wavelength (barely resolved ) 15 nm lines not resolved, no modulation W. Chao et al., Opt. Lett. 28, 2019 (Nov 2003) ZP microscopy Apps1.ppt

26 New Results Using Overlay Nanofabrication: Outer Zone Width of 15 nm Zone plate lenses made using a new, e-beam based nanofabrication technique have extended outer zones from 25 nm to 15 nm. The new lenses work as expected, resolving fine patterns not seen previously Shorter depth of focus (λ/na 2 ) opens the opportunity for soft x-ray optical sectioning of biological material. New zone plate lens with 15 nm outer zone width Normalized Image Modulation !r MZP =25nm " =0.21 to 0.42 Calculated Measured!r MZP =15nm " =0.19 to 0.38 Calculated Measured Soft x-ray image of 15 nm Cr/Si lines & spaces 0.0 1/period (um -1 ) half-period (nm) nm W. Chao, B. Harteneck, J.A. Liddle, E. Anderson and D. Attwood Soft X-Ray Microscopy at a Spatial Resolution Better than 15 nm, Nature 435, 1210 (30 June 2005). ZP microscopy Apps1.ppt

27 Zone Plate Parameters for r = 15 nm, λ = 2.5 nm and λ = 1.5 nm λ = 2.5 nm 1.5 nm r = 15 nm N = 500 D = 30 µm f = 180 µm 300 µm NA = nm (σ = 0) Res = 12 nm (σ = 0.4) DOF = ± 180 nm ±300 nm λ/λ = 1/500

28 Applications of Soft X-Ray Microscopy Magnetic Recording Materials Cryo Microscopy for the Life Sciences Cell border 100 nm lines & spaces Nucleoli Cell border 1 µm Nucleus Fe L ev FeTbCo Multilayer with Al Capping Layer Cryo X-Ray Microscopy of 3T3 Fibroblast Cells Protein Labeled Microtubule Network Courtesy of P. Fischer (Max Planck) and G. Denbeaux (CXRO/LBNL) Courtesy of C. Larabell (UCSF) and W. Meyer-Ilse (CXRO/LBNL) ZP microscopy Apps2.ppt

29 The Water Window for Biological X-Ray Microscopy ZP microscopy Apps2.ppt

30 Fast Freeze Cryo Fixation Strongly Mitigates Radiation Dose Effects Fast Freeze Helium passes through LN, is cooled, and directed onto sample windows Temperature (Celsius) ΔT Δt = 50 c 16 ms Time (milliseconds) W. Meyer-Ilse, G. Denbeaux, L. Johnson, A. Pearson (CXRO-LBNL) ZP microscopy Apps2.ppt

31 Organelle Details Imaged with Cryogenic Preservation and High Spatial Resolution Cryo x-ray microscopy of 3T3 fibroblast cells ER? Filopodia Cell border Nucleoli Nucleus Cell border Cell border Nucleus Nucleoli C. Larabell, D. Yager, D. Hamamoto, M. Bissell, T. Shin (LBNL Life Sciences Division) W. Meyer-Ilse, G. Denbeaux, L. Johnson, A. Pearson (CXRO-LBNL) ZP microscopy Apps2.ppt

32 Bending Magnet Radiation Used With a Soft X-Ray Microscope to Form a High Resolution Image of a Whole, Hydrated Mouse Epithelial Cell Courtesy of C. Larabell and W. Meyer-Ilse (LBNL) hw = 520 ev 32 µm x 32 µm Ag enhanced Au labeling of the microtubule network, color coded blue. Cell nucleus and nucleoli, moderately absorbing, coded orange. Less absorbing aqueous regions coded black. W. Meyer-Ilse et al. J. Microsc. 201, 395 (2001) ZP microscopy Apps2.ppt

33 National Center for X-ray Tomography XM-2: A New, Upgraded Microscope Dedicated to Soft X-Ray Biotomography Dedicated to life sciences research Cryotomography without apparatus interruption Interchangeable objective lenses (tradeoff resolution, depth of focus, working distance) Improved resolution, lens efficiency, image contrast and uniformity Improved cryo transport Improved computational image reconstruction and analysis More flexible use of phase contrast ZP microscopy Apps2.ppt

34 Magnetic X-Ray Microscopy Using X-Ray Magnetic Circular Dichroism (XMCD) Magnetic X-Ray Microscopy High spatial resolution in transmission Bulk sensitive (thin films) Complements surface sensitive PEEM Good elemental sensitivity Good spin-orbit sensitivity Allows applied magnetic field Insensitive to capping layers In-plane and out-of-plane measurements Courtesy of P. Fischer, Wuerzberg and G.Denbeaux, CXRO/LBNL ZP microscopy Apps2.ppt

35 Imaging of Thermomagnetically Written Bits in MO Media 100 nm lines & spaces 1 µm MFM-image SiN(70 nm)/tb 25 (Fe 75 Co 25 ) 75 (50 nm)/sin(20 nm)/al(30 nm)/sin(20 nm) P. Fischer et al., Wuerzburg; N. Takagi et al., Sanyo; G. Denbeaux et al., CXRO/LBNL ZP microscopy Apps2.ppt

36 Magnetic Domains Imaged at Different Photons Energies 1 µm FeGd Multilayer Contrast reversal hω = 704 ev below Fe L-edges hω = ev Fe L 3 -edge hω = ev Fe L 2 -edge P. Fischer, T. Eimueller, M. Koehler (U. Wuerzberg) S. Tsunashima (U. Nagoya) and N. Tagaki (Sanyo) G. Denbeaux, L. Johnson, A. Pearson (CXRO-LBNL) ZP microscopy Apps2.ppt

37 Nanoscale Local Hysteresis 200n m H ext 0Intensity (A. U.) -3 D.-H. Kim et al., J. Appl. Phys. (2005) accepted 5 6 Field (A. U.) ZP microscopy Apps2.ppt

38 Electromigration in Latest Technology Computer Chips with Cu vias Connecting Multilevel Metallization Layers SEM micrograph X-ray micrograph imaged at 1.8 kev Cu interconnect X-rays Cu via HVTEM (0.8 MeV electrons) TXM (1.8 kev photons) Wafer 1 µm G. Denbeaux, E. Anderson, A. Pearson and B. Bates (CXRO) M. Meyer and E. Zschech (AMD Saxony Manufacturing GmbH) / E. Stach (NCEM / LBNL) High current density Courtesy of Gerd Schneider (BESSY) ZP microscopy Apps2.ppt

39 Using Phase Effects to Achieve Higher Diffraction Efficiency λ ZP (3.29) For a π-phase shift t f a factor of four can be gained in diffraction efficiency. For soft x-rays and EUV all materials are partially absorbing (9.25) (3.12) Optimization is a function of δ/β, as discussed by J. Kirz, J. Opt. Soc. Am. 64, 301 (1974) and by G.R. Morrison, Ch. 8 in A. Michette and C. Buckley, X-Ray Science and Technology (IOP, Bristol, 1993). Ch09_F08.modifVG.ai

40 Hard X-Ray Zone Plate Microscopy Images courtesy of the Synchrotron Radiation Research Center (SRRC), Taiwan Gung-Chian Yin Mau-Tsu Tang and Xradia, Concord, CA Wenbing Yun Michael Feser HardXRzoneplateMicros.ai

41 The Transmission X-ray Microscope Phase Ring Zone plate optical system Condenser Tube Ion Chamber condenser Zoneplate objective 10 cm Monochromatic X-rays Sample mount and sample Image manipulation system

42 The resolution reaches 30 nm. APL v89,221122, µm (a) 1 µm (b) 3 µm 1 µm (c) 1 µm (d)

43 TXM with Zernike s phase contrast method 1 µm HeLa cell with Nicole stained Plastic zoneplate of 1 µm thick

44 The tomography close 60 nm. APL. Vol 88, ,2006

45 Nature: Aug /20/2007 Berkeley CXRO 8

46 Application: Advanced IC Device Failure analysis and R&D of advanced IC devices 3/20/2007 Berkeley CXRO 25

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51 SSRL nanoxct installation Installed Dec 2006 in 1 day 1s exposure time at 8keV Zernike phase contrast <30nm resolution in first order imaging mode 3/20/2007 Berkeley CXRO 52

52 The Scanning Soft X-Ray Microscope ZP microscopy Apps2.ppt

53 An Undulator Beamline for Scanning X-Ray Microscopy ZP microscopy Apps2.ppt

54 Coherent Power for an EPU at the ALS ZP microscopy Apps2.ppt

55 Spectromicroscopy: High Spatial and High Spectral Resolution Studies of Surfaces and Thin Films ZP microscopy Apps2.ppt

56 Biofilm from Saskatoon River ALS-MES RESULTS Ni, Fe, Mn, Ca, K, O, C elemental map, ( there was no sign of Cr.) Different oxidation states for Fe and Ni OD Fe 2p µm 0.5 Protein (gray), Ca, K µm Different oxidation states (minerals) found for Fe & Ni Tohru Araki, Adam Hitchcock (McMaster University) Tolek Tyliszczak, LBNL Sample from: John Lawrence, George Swerhone (NWRI- Saskatoon), Gary Leppard (NWRI-CCIW) ZP microscopy Apps2.ppt

57 Patterned Polymer Photoresists ALS-MES M.K. Gilles, R. Planques, S.R. Leone LBNL Samples from B. Hinsberg, F. Huele IBM Almaden 280 ev 290 ev Exposure to UV light results in loss of carbonyl peak Map chemical spectra taken of pure samples Onto a sample containing both components Courtesy of Mary Gilles, LBNL ZP microscopy Apps2.ppt

58 The Nanowriter: High Resolution Electron Beam Writing With High Placement Accuracy Deflection coils High brightness thermal field emission source and extraction electrodes Condenser lens, beam defining aperture and transfer lens Blanking plates and aperture Final electron focusing lens kev electron beam focused to 3-10 nm spot size Deflection electronics Pattern generator System control computer Thin resist recording layer on a multilevel wafer Wafer stage (stationary during exposure) Courtesy of E. Anderson, LBNL Ch09_F43VG.ai

59 LBNL Nanowriter: Unique Ultra-high Resolution, High Accuracy Electron Beam Lithography Tool Parameter Beam size Beam placement Stitching Beam voltage Beam current Speed Deflection field Interferometer Wafer size Real time detection and feedback Key Specifications Nanowriter 5.0 nm 2.5 nm (New C3 lens) 2.5 nm (65 µm field) 20 nm (512 µm field) 20 nm (1 cm field) kv 1 na at 10 nm na at 2.5 nm (new C3 lens) 25 MHz 16 bit λ/1024 8" Backscattered, transmitted and secondary electrons; digital image processing Courtesy of E. Anderson, LBNL Ch09_Nanowriter_Apr04.ai

60 Nanofabrication is Critical for High Fidelity, High Aspect Ratio Zone Plates 1. Expose HSQ resist 2. Develop Cross-linked polymer Si 3 N 4 Etch resistant plating base Cross-linked polymer Si 3 N 4 Si Si 3. Cryogenic ICP Etch 4. Plate Si 3 N 4 Si 3 N 4 Si Si 5. Strip Resist 6. Strip Si 3 N 4 and Cr/Au Plating Base Si 3 N 4 Si Si Courtesy of E. Anderson, A. Liddle, W. Chao, D. Olynick, and B. Harteneck (LBNL) ZP microscopy Apps1.ppt