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Zone Plate Microscopy

David Attwood

University of California, Berkeley

(http://www.coe.berkeley.edu/AST/srms)

Zone Plate Microscopy and Applications, EE290F, 12 April 2007

∆r

λ

θf

f +

D = 2rN

rn

r2r1 nλ

2

Zone Plate lens

Sample

Soft X-ray CCD

λ

Zone Plate Lens

Soft X-Ray Microscope

Zone Plate Formulae

r2 = nλf +

λ = 2.5 nm,∆r = 25 nmN = 618

0.63 mm

0.05 µm

1 µm

1/700

1.22∆r = 30 nm

0.8∆r = 19 nm

63 µmD = 4N∆r

NA =

f =

nn2λ2

4

4N(∆r)2

λ

λ2∆r

≤1N

∆λλ

Res. = k1 = 2k1∆rλ

NA

DOF = ± λ

(NA)212

(9.9)

(9.13)

(9.14)

(9.15)

(9.50)

(9.52)

k1 = 0.61(σ = 0)

k1 = 0.4(σ = 0.45)

Ch09_F00modif_Oct04.ai

Zone Plates for Soft X-Ray Image Formation

Professor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007

Ch09_F21modif_Nov05.ai

Two Common Soft X-Ray Microscopes

Aperture(OSA)

Detector

Samplescanning

stage

Zone Plate lens

Sample

Soft X-ray CCD

λ

λ

Full-FieldMicroscope

ScanningMicroscope

• 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

Zone Plate lens


Ch09_F01VG.ai

A Fresnel Zone Plate Lensfor X-Ray Microscopy

E. Anderson, LBNL

Zone Plate Microscopy and Applications, EE290F, 12 April 2007Professor David AttwoodUniv. California, Berkeley

Ch09_F03VGrevApril04.ai

Diffraction from a Transmission Grating

d

d

(+1)

(–1)

(0)

θθ

λ

λ

θ

;

(50% absorbed)

(9.2)

(9.24)


Ch09_F05VG.ai

A Fresnel Zone Plate Lens

∆r

λ

θf

f +

f2 + r2 = f + 2

D = 2rN

rn

r2r1

nλ2

nλ2n

nr2 = nλf + n2λ2

4

(9.9)

(9.10)

(9.8)


Ch9_F05_Nov05.ai

A Fresnel Zone Plate Lens

(9.13)

(9.14)

Define the outer zone width for n → N,

(9.15)

=

and from (9.12) above

D2f

(9.16)

(9.11)

(9.12)

(from 9.10)but λ f =

∴

∆r

λ

θf

f +

D = 2rN

rn

r2r1

nλ2

2


Ch09_F02_modif_VG.ai

A Fresnel Zone Plate Lens Used as aDiffractive Lens for Point to Point Imaging

∆r

D

S

P

p

pn

q

qn

(9.17)

(9.18)


Zone Plate Diffractive Focusing for Higher Orders

ZP

(–5)(–3)

(m = –1)

(m = –5) (–3)

(–1)OSA

λ f5

5nλ2

+

f3

3nλ2

+

nλ2

f +

f

f5 f

3

(9.19)

(9.24)

1m

rN2

Nλfm =

1mfm = f1

Ch09_F08_Nov05.aiProfessor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007

Ch09_F11VG.ai

Diffraction from a Fresnel Zone Plate

(9.45)

(9.46)

λ

ξ

θ

D

y

P(x,y)

R

z

xr

η

ρ2 = ξ2 + η2∆r

S(ξ,η)

00 5 10

kaθ

N2

N2

N2

2

kaθ = 3.832

Foc

al p

lane

inte

nsity

, I(θ

)/I o

2J1(kaθ)

(kaθ)

2

Airy pattern


Ch09_F14_April04.ai

Resolving Two Point Sources

r

ΙRayleigh

(b)(a)

rnull = 0.61λ/NArnull = 0.61λ/NA rnull

∆∆

• 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 = = 1.22 ∆r0.61 λ

NA


Opaquezones

Coherent illumination(σ = 0)

Spatialresolution:

1.2 ∆r

∆r

λx

Fresnel Zone Plate Lens for Diffractive Focusing of Spatially Coherent X-rays

Ch09_FresnelZP_Apr07.ai

Rescoh =

NA =

∴ Rescoh = 1.22 ∆r

(σ = 0, see first slide)

0.61 λNAλ

2∆r


Ch09_F19_Nov05.ai

Partially Coherent Illumination Permits ImprovedSpatial Resolution by a Factor Approaching Two

d2

2πd

2π(d/2)

d2

d

(a)

(b)

(c)

ks

ks

ks

ki

ki

ki

ki

θ

2θ

θ

2θ

σ = (for n = 1)NAillum.NAobj.

sinθillum.sinθobj.

θobj.

θillum.


Ch09_F10.2_Nov05.ai

Optical Transfer Properties with VaryingDegrees of Partially Coherent Illumination

0 1 2

0.5

1.0

App

aren

t tra

nsfe

r fu

nctio

n

Spatial frequency (NA/λ)

σ = ∞ (incoherent)

σ = 0.6

σ = 0.3

σ = 0 (coherent)

σ = (for n = 1)NAillum.NAobj.

sinθillum.sinθobj.


Ch09_10.3.ai

Intensity Versus Position for a Sharp Edge ObservedWith Coherent and Partially Coherent Radiation

–2 –1 0(edge)

1

Distance (λ/2NA)

Inte

nsity

2 3

σ = ∞σ = 1.5σ = 1.0σ = 0.9σ = 0.8σ = 0.6σ = 0.2

1.3

1.0

0.5

0

Courtesy of M. O’Toole and A. Neureuther (UC Berkeley).Professor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007

Ch09_F18_Nov05.ai

Depth of Focus and Spectral Bandwidth

(9.50)

(9.51)

(9.52)∆r

λ

z = f

z

focal plane, z = f

two depths of focus away, z = f –

four depths of focus away, z = f –

λ2(NA)2

λ(NA)2

2λ(NA)2


Ch09_WhyDOFscale.ai

Why does DOF Scale as /NA2?

High NA

Low NA

θ

λ

0.6λ/NADOF/2

DOF/2

tanθ =

tanθ ~ sinθ = NA

∴ DOF

DOF = ±

for small θ

in the text, eq. 9.50:

0.6λNA

0.6λNA

1.2λ/NAtanθDOF =

DOF

1.2λNA2

12

λ(NA)2

θ

θλ

DOF


Ch09_TestPattrn.ai

Test Pattern for NanometerSoft X-ray Imaging

E. Anderson, D. Olynick, B. Harteneck, E. Veklerov, LBNL


ZP microscopy Apps2.pptProfessor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007

The XM-1 Soft X-Ray Microscopeat the Advanced Light Source (ALS)

E = 250 - 1.8 keVλ = 0.7 nm - 5 nm

• 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

13


High Resolution Zone-Plate Microscope XM-1at the ALS

• Well engineered• Sample indexing• Tiling for larger field

of view• Pre-focused• High sample throughput• Illumination important• Phase contrast


Bending Magnet Photon Flux at the ALS

Professor David AttwoodAST 210/EECS 213Univ. California, Berkeley


Micro Zone PlatesΔr = 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 PlateΔr = 55 nm (40 nm), Δt = 200 nm (22%). N = 41,000, D = 9 mm, f = 207 mm,NA = 0.022 @ 2.4 nm. σ = 0.45 with Δr = 25 nm micro zone plate.

MagnificationM = 2400 to 3100; 24 µm CCD pixel 8 nm at sample.Spectral Bandpassλ/Δλ = 700, per pixel, 2 µmD field.λ/Δλ = 500 with shaker, 10 µmD field.CCD CameraBack thinned, soft x-ray sensitive. 1024 x 1024 (2048 x 2048), 24 µm square pixels. 60 -70% efficient.Exposure Time1-5 seconds, 103 photons/pixel, 8 µm diameter at sample (2.5 sec @ 400 mA, 2 x 2 binning,Δr = 25 nm)

XM-1 Parameters


New Overlay Nanofabrication Techniquefor Narrower Outer Zones

Δr = 15 nmΔt = 90 nmOverlay ~ 2 nm accuracy–

Courtesy of J.A. Liddle, E.H. Anderson, B. Harteneck and W. Chao, LBNL


Multilayer Mirror Coatings Can Be Thinnedand Used As Sub-20 nm Test Patterns

High quality test patterns can be fabricatedwith sections as thin as 5 nm.

SEM Micrographof Cr/Si test pattern

ΔtCourtesy of W. Chao, UC Berkeley and CXRO/LBNL.


Near Diffraction Limited Soft X-Ray Microscopy:20 nm Spatial Resolution at 2.07 nm Wavelength

15 nm linesnot resolved,no modulation

(barely “resolved”)

W. Chao et al.,Opt. Lett. 28, 2019 (Nov 2003)


New Results Using Overlay Nanofabrication:Outer Zone Width of 15 nm

• Zone plate lenses made using a new, e-beam based nanofabrication techniquehave 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/NA2) opens the opportunity for soft x-ray “optical

sectioning” of biological material.

15 20 25 30 35 40 45 50 550.0

0.2

0.4

0.6

0.8

1.0

15

1/period (um-1)

half-period (nm) 25 20 12.5 10

Norm

aliz

ed Im

age M

odula

tion

!rMZP

=25nm

" =0.21 to 0.42

Calculated Measured

!rMZP

=15nm

" =0.19 to 0.38

Calculated Measured

100 nm

Soft x-ray image of15 nm Cr/Si lines & spaces

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).

New zone plate lens with15 nm outer zone width

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 nmN = 500D = 30 µmf = 180 µm 300 µmNA = 0.083 0.05 18 nm (σ = 0) 12 nm (σ = 0.4)DOF = ± 180 nm ±300 nm∆λ/λ = 1/500

Res =



Fe L3 @ 707.5 eV

1 µm Nucleus

Cell border

NucleoliNucleoli

Cellborder

Cryo X-Ray Microscopyof 3T3 Fibroblast Cells

100 nmlines &spaces

Protein LabeledMicrotubule Network

FeTbCo Multilayerwith Al Capping Layer

Magnetic RecordingMaterials

Cryo Microscopy for the LifeSciences

Courtesy of P. Fischer (Max Planck)and G. Denbeaux (CXRO/LBNL)

Courtesy of C. Larabell (UCSF)and W. Meyer-Ilse (CXRO/LBNL)

Applications of Soft X-Ray Microscopy


The Water Window forBiological X-Ray Microscopy


Helium passes through LN, is cooled,and directed onto sample windows

W. Meyer-Ilse, G. Denbeaux, L. Johnson, A. Pearson (CXRO-LBNL)

-150

-100

-50

0

50

-10 0 10 20 30 40 50 60 70 80 90 100

Time (milliseconds)

Tem

pera

ture

(Cel

sius

)50°c

16 msΔTΔt

= –

Fast Freeze

Fast Freeze Cryo Fixation Strongly MitigatesRadiation Dose Effects


Cell border

Nucleus

NucleoliNucleus

Cell border

Nucleoli

Cell border

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)

ER?Filopodia

Cryo x-ray microscopy of 3T3 fibroblast cells

Organelle Details Imaged with CryogenicPreservation and High Spatial Resolution


Bending Magnet Radiation Used With a Soft X-RayMicroscope to Form a High Resolution Image of a

Whole, Hydrated Mouse Epithelial Cell

hw = 520 eV

32 µm x 32 µm

Ag enhanced Au labelingof the microtubule network,color coded blue.

Cell nucleus and nucleoli,moderately absorbing,coded orange.

Less absorbing aqueousregions coded black.

W. Meyer-Ilse et al.J. Microsc. 201, 395 (2001)

Courtesy of C. Larabell and W. Meyer-Ilse (LBNL)


XM-2: A New, Upgraded MicroscopeDedicated 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

National Center for X-ray Tomography


• 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

Magnetic X-Ray Microscopy

Courtesy of P. Fischer, Wuerzberg and G.Denbeaux, CXRO/LBNL

Magnetic X-Ray Microscopy Using X-RayMagnetic Circular Dichroism (XMCD)


1 µm

SiN(70 nm)/Tb25(Fe75Co25)75(50 nm)/SiN(20 nm)/Al(30 nm)/SiN(20 nm)

MFM-image

P. Fischer et al., Wuerzburg; N. Takagi et al., Sanyo; G. Denbeaux et al., CXRO/LBNL

100 nm lines & spaces

Imaging of ThermomagneticallyWritten Bits in MO Media


Magnetic Domains Imaged atDifferent Photons Energies

P. Fischer, T. Eimueller, M. Koehler (U. Wuerzberg)S. Tsunashima (U. Nagoya) and N. Tagaki (Sanyo)G. Denbeaux, L. Johnson, A. Pearson (CXRO-LBNL)

FeGd MultilayerContrastreversal

1 µm

hω = 720.5eV

Fe L2-edge

hω = 707.5eV

Fe L3-edge

hω = 704 eVbelow Fe L-edges


Nanoscale Local Hysteresis

200nm

5 6

-3

0

Inte

nsity (

A.

U.)

Field (A. U.)

Hext

D.-H. Kim et al., J. Appl. Phys. (2005) accepted


Electromigration in Latest TechnologyComputer Chips with Cu vias Connecting

Multilevel Metallization Layers

G. Denbeaux, E. Anderson, A. Pearson and B. Bates (CXRO)M. Meyer and E. Zschech (AMD Saxony Manufacturing GmbH) / E. Stach (NCEM / LBNL)

SEM micrograph X-ray micrograph imaged at 1.8 keV

X-rays

High current density

Cu interconnect

Cu via

Wafer

1 µm

HVTEM (0.8 MeV electrons)TXM (1.8 keV photons)

Courtesy of Gerd Schneider (BESSY)

Ch09_F08.modifVG.ai

Using Phase Effects to AchieveHigher Diffraction Efficiency

ZP

λ

f∆t

For a π-phase shift

a factor of four can be gained in diffraction efficiency. For soft x-rays and EUV all materials are partially absorbing

Optimization is a function of δ/β, asdiscussed 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).

(3.29)

(3.12)

(9.25)


HardXRzoneplateMicros.ai

Hard X-Ray Zone Plate Microscopy


Images courtesy of the Synchrotron Radiation Research Center(SRRC), Taiwan Gung-Chian Yin Mau-Tsu Tangand Xradia, Concord, CA Wenbing Yun Michael Feser

Zone plate optical systemZone plate optical system Condenser TubeCondenser Tube

Monochromatic X-raysMonochromatic X-rays

The Transmission X-ray MicroscopeThe Transmission X-ray Microscope

10 cm

Ion ChamberIon Chamber

Phase RingPhase Ring

Sample mount and sampleSample mount and samplemanipulation systemmanipulation system

condenser

Zoneplateobjective

Image

The resolution reaches 30 nm. APL v89,221122,2006

3 µm

1 µm(a)

1 µm1 µm

3 µm (b)

(c) (d)

TXM with Zernike’s phase contrast method

HeLa cell with Nicole stained

1 µm

Plastic zoneplate of 1 µm thick

APL. Vol 88, 241115,2006The tomography close 60 nm.

3/20/2007 Berkeley CXRO 8

Nature: Aug Nature: Aug 20062006


Application: Advanced IC DeviceFailure analysis and R&D of advanced IC devices


SSRL nanoXCT installation• Installed Dec 2006 in 1 day• 1s exposure time at 8keV Zernike phase contrast• <30nm resolution in first order imaging mode


The Scanning Soft X-Ray Microscope


An Undulator Beamline forScanning X-Ray Microscopy


Coherent Power for an EPU at the ALS


Spectromicroscopy: High Spatial and High SpectralResolution Studies of Surfaces and Thin Films


RESULTS•Ni, Fe, Mn, Ca, K, O, C elemental map,( there was no sign of Cr.)•Different oxidation states for Fe and Ni

Protein (gray), Ca, K 700 705 710 715 720 725

OD

1.5

1.0

0.5

0

1 µm

Different oxidation states (minerals) found for Fe & Ni

Fe 2p

5 µm

Tohru Araki, Adam Hitchcock (McMaster University)Tolek Tyliszczak, LBNLSample from: John Lawrence, George Swerhone (NWRI-Saskatoon), Gary Leppard (NWRI-CCIW)

Biofilm from Saskatoon RiverALS-MES 11.0.2


Map chemical spectra taken of pure samplesOnto a sample containing both components

M.K. Gilles, R. Planques, S.R. Leone LBNL

Samples from B. Hinsberg, F. Huele IBM Almaden

Exposure to UV light results in loss of carbonyl peak

280 eV 290 eV

Courtesy of Mary Gilles, LBNL

Patterned Polymer PhotoresistsALS-MES 11.0.2

Ch09_F43VG.ai

The Nanowriter: High Resolution Electron Beam Writing With High Placement Accuracy

High brightness thermal field emission source and extraction electrodes

Condenser lens, beam definingaperture and transfer lens

Blanking plates and aperture

50-100 keV electron beam focused to 3-10 nm spot size

Deflection coils

Final electron focusing lens

Deflectionelectronics Pattern

generator System controlcomputer

Thin resist recording layeron a multilevel wafer

Wafer stage (stationaryduring exposure)

Courtesy of E. Anderson, LBNLProfessor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007

Ch09_Nanowriter_Apr04.ai

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 detectionand feedback

Nanowriter

5.0 nm2.5 nm (New C3 lens)

2.5 nm (65 µm field)20 nm (512 µm field)

20 nm (1 cm field)

20-100 kV

1 nA at 10 nm1.0-0.2 nA at 2.5 nm (new C3 lens)

25 MHz

16 bit

λ/1024

8"

Backscattered, transmitted and secondary electrons;digital image processing

Key Specifications

Courtesy of E. Anderson, LBNLProfessor David AttwoodUniv. California, Berkeley Zone Plate Microscopy and Applications, EE290F, 12 April 2007


Nanofabrication is Critical for High Fidelity,High Aspect Ratio Zone Plates

Courtesy of E. Anderson, A. Liddle, W. Chao, D. Olynick, and B. Harteneck (LBNL)

Etch resistantplating base

1. Expose

Si

Cross-linked polymerSi3N4

HSQ resist

6. Strip Si3N4 and Cr/Au Plating Base

Si

2. Develop

Si

Cross-linked polymerSi3N4

3. Cryogenic ICP Etch

Si

Si3N4

4. Plate

Si

Si3N4

5. Strip Resist

Si

Si3N4

Zone Plate Microscopy - University of California, Berkeleyattwood/srms/2007/Lec22.pdf ·...

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