Using resonant soft X-ray scattering to image …Using resonant soft X-ray scattering to image...

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Using resonant soft X-ray scattering to image patterns on undeveloped resists

Guillaume Freychet, I. Cordova, D. Kumar, T. McAfee, C. Anderson, P. Naulleau, C. Wang and Alexander Hexemer

June, 14th 2018

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Context for the semi-conductor industry

With the size reduction of the objects, any sub-nm defects will impact strongly

the performance of the device

1D array : Line gratings

Sub-nm resolution

✓ Pitch✓ Linewidth✓ Line height✓ Roughness✓ Sidewall angle

Parameters to control :

H𝜷

𝝎0

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Small Angle X-ray Scattering (SAXS)

✓Probe electronic density contrast

✓Small angle scattering: probe 1-1000 nm

q =2p

lsin2q

H

qxz (nm-1)

qy

(nm

-1)

2𝞱φ

z

y

x

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Small Angle x-ray scattering (SAXS) on line gratings

Distorted Wave Born Approximation

H

qxz (nm-1)q

y(n

m-1

)2𝞱φ

z

y

x

2𝞱𝜶f

qp

er(n

m-1

)

qpar (nm-1)

xz

y

φ

Grazing-incidence SAXS (GISAXS)

✓ Small incidence angle < 0.2 deg✓ Probe thin films on Silicon wafer (700 μm)

✓ Transmission configuration✓ High energy x-ray source

44

D. F. Sunday et al., ACS Appl. Mater. Interfaces (2017)

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Ewald sphere

Sample surface

Rods coming from the grating

2𝞱𝜶f

qp

er(n

m-1

)

qpar (nm-1)

xz

y

φ

1

2

3

4

56

qper(nm-1)

Inte

nsi

ty (

a. u

.)

6.0

4.0

3.0

2.0

1.0

5.0

7.0

0.5 0.7 0.8 0.90.6

1

2

3

4

5

6

b)

Fitted profileTEM profile

Rotation of the gratings(along z)

1D vertical cut

Critical-Dimension GISAXS

Fit using genetic algorithm

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Resonant Soft X-Ray Scattering (RSoXS)

Small Angle X-Ray Scattering

Electronic density:|δ2 + β2|

Credit: Guinnier A. et al, Ann Phys, 1939, 12:161–237

X-Ray Beam

X-Ray Absorption

Credit: Wanli Yang, ALS

1s

2s

2p

Tunable photon

XRD

Reconstruction of a latent image (before removal of the exposed resist)

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Credit: C. Wang et al, Nano Lett., 2011, 11, 3906

Triblock copolymer:

β

δ

Electronic density|δ2 + β2|

280 eV 284 eV

✓ Tune the energy to enhance the scattering contrast

✓ Before the absorption edge to reduce beam damage

284 eV 280 eV

RSoXS applications

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11.0.1.2 Beamline at the ALS

Ener

gy (

eV)

X-Rays

Main chamber

C. Wang I. Cordova

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284.6 eV 285.2 eV

CD-GIRSOXS of latent imageChain-scission EUV resist:

✓ E-beam exposition ✓ 200 nm pitch line gratings✓ Post-Exposure baking

t1

t2

Exposition + bake:Chain scission

Modification of the carbon environment Modification of the β and δ

Introduction of a scattering contrast

NEXAFS spectra of the resist

Energy (eV)

Peak related to a specific carbon

bonds

Contrast between exposed/unexposed resist at 284.6 eV

✓ 284.6 eV: Electronic density contrast✓ 285.2 eV: No electronic density contrast

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CD-GISAXS of latent image using Resonant scattering

Reconstruction of the 3D shape of a latent image

123

1

2

3

Extracted profile

1D vertical cut

10

✓ New perspectives to control the 3D shape of a latent image✓ Short measurement time: 10 seconds✓ Beam damage?

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Conclusion

✓ 3D reconstruction of the latent image with a sub-nm resolution

✓ Trapezoidal shape after the exposition

✓ Comparison before and after development

vs

FEM wafer (IMEC)

✓ Test on different resists (different elements edges)

✓ Quantification of the roughness

✓ Study beam damage on the sample

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Acknowledgements

Isvar CordovaTerry McAfeeWei XuGreg SuDavid KilcoyneCheng WangAlexander Hexemer

Thank you for your attention!

Patrick NaulleauWeilun ChaoChristopher Anderson

Daniel StaaksScott DhuevPeter Ercius

Ronal PandolfiDinesh KumarJamie A. Sethian

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Acknowledgements

Thank you for your attention!