euv and electron-beam lithography performance...

© 2009 IBM Corporation

IBM Almaden Research Center

EUV and electron-beam lithography performance comparison

Luisa D. Bozano, Phillip Brock, Hoa Truong, Gregory M. Wallraff, Elizabeth Lofano,Martha Sanchez, Robert Allen, IBM Almaden Research Ctr. (United States)Karen Petrillo Albany Sematech

R.D. Allen et al J. of Photopolymer Science and Tech, 22(1), (2009), 25-29G. Wallraff et al. SPIE presentation 2010

© 2011 IBM Corporation2

Outline

§Background

§Motivation:– Proc. SPIE 7972, 797218 (2011)– recent experimental results

§Materials analyzed– Bound PAG

• Advantages of Bound PAG– Unbound PAG

§E-beam vs EUV results comparison


Background: EUV vs e-beam

§ Similarities and differences in acid generation between e-beam (EB) and EUV by Prof Kozawa and Prof Tagawa (Jpn J. Appl. Phys. 49 (2010)):

– Both radiation based phenomena– Photoacids interact with low energy electrons deposited in resist materials via

ionization– EUV has a larger efficiency in acid yield

Material EUV E-beam 193nm correlation

Commercial 193 resist (IBM/LBNL)

terrible good good bad

Commercial EUV Resist (Albany)

good good good good

Wallraff EIPBN 2009

Seiya Masuda Proc. of SPIE Vol. 6153 615342-2 2006 Takeo Watanabe Proc. of SPIE Vol. 6153 615343-5 2006Toshikage Asakura J. of Photopolymer Science and Technology Vol 22, 89 (2009)Takeyoshi Mimura, EUVL Symposium Oct29 (2007)Daisuke Shimizu, Proc. Of SPIE Vol. 6153 615344-1 (2006)


Motivation for this study

EUV E-Beam

Chemically amplified bound PAG resists (EUV resists):binding the photoacid generator (PAG) anion to the polymer backbone

• Higher resolution demonstrated by a variety of sources• Acid diffusion is extremely low (relative to unbound version) -Wallraff, SPIE 2010

limited access More accessible

E-beam quick turn around analysis for EUV resist performanceBoth high energy radiation- induced sources Both high resolution toolsOutgassing less of a concern

But how good is the correlation?


Criteria for evaluation EUV vs E-beam correlation

E-beam (Almaden)

§100KeV

§5 nA beam (for contrast curves)

§0.5nA beam (for imaging)

§13 nm spot size

§No proximity correction

EUV (Berkeley)

§0.3 NA

§45-degree dipolar

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• Relative dose prediction• Performance (CD resolution, LER)• Resist shrinkage/film loss/outgassing


Analyzed Materials: Evaluated resists from vendors and in house

Resist materials

Bound PAG Unbound PAG

Series A Resist A1 X

Resist A2 X

Resist A3 X

Series B Resist B1 X

Resist B2 X

Resist B3 X

Series C Resist C1 X

Resist C2 X

Resist C3 X

Series D Resist D1 X

Resist D2 X

Resist D3 X

Resist D4 X6


SERIES A

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EUV-MET vs E-beam Contrast Curves

EUV results E-Beam results

Relative performance between the 3 formulations correlates quite nicely for e-beam vs EUV.

• Resist A2 and A3 comparable in profile and speed• Resist A1 slowest

• E-beam relative dose to EUV= 10X

Resist A1Resist A2Resist A3

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Imaging comparison

Resist EUV 30nm E-beam 30nm Comment

Resist A1

E-Beam results consistently show top skin and defects not present in EUV

Resist A2

E-beam doesn’t predict correctly relative dose for EUV

Resist A3

Resist A1 highestEUV doseResist A3 highest e-beam dose

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10.66 mJ

9.23 mJ

10.50 mJ 90 uC/cm2

60 uC/cm2

65 uC/cm2


SERIES B

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E-beam 5X slower than EUVNo good relative dose correlation between the 2 formulations:

• in e-beam similar dose for Resist B1 and B2• B2 slower than B1 in EUV

Resist B1 and B2: e-beam not good prediction for EUV behavior

EUV MET E-beam

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Resist B3: e-beam better than EUV

• E-beam imaging better than EUV:• Less web and scum

• E-beam relative dose to EUV= 7/8X

35uC/cm2

31.0/7.7/5.6

4.98 mJ/cm2

EUV MET E-beam

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SERIES C

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Series C contrast curve comparison: EUV and e-beam similar contrast

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E-beam relative dose to EUV: 10X

EUV E-beam


Imaging comparison: good EUV vs e-beam correlation

Resist EUV 30nm E-beam 30nm Comment

Resist C1

Quite consistent results between e-beam and EUV. Good e-beam vsEUV correlation

Resist C2

Same good correlation

Resist C3

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25-35 mJ/cm2

13.4 mJ/cm2

18.75 mJ/cm2

93 uC/cm2

150 uC/cm2


SERIES DAnalysis performed

Bound vs unboundQuencher effect

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Imaging comparison: e-beam better than EUV

resist EUV E-beam Comments

D1Unbound version

EUV had poor resolution for less than 60nm lines

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4.00 mJ/cm2

LER=2.9 nm

114 mC/cm2

LER=2.7 nm

For EUV the unbound version of D1 performed poorly. E-beam reached much better line resolution.However they were both showing low LER


E-beam contrast curve comparison between resists: base vs no base

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• E-beam bound PAG resist still good contrast curves without base.• E-beam sensitivity for formulation w/o quencher vs w/ quencher is

D1=1.75xD2= 2x


Resist EUV 30nmw/ quencher

EUV 30nmw/o quencher

E-beam 30nmw/ quencher

E-beam 30nmw/o quencher

Resist D1

Resist D2

Resist D3

Resist D4

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165 mC/cm2 75 mC/cm29.45 mJ/cm2 3.33 mJ/cm2

135 mC/cm2 57 mC/cm210 mJ/cm2

Didn’t obtain 30nm resolution

480 mC/cm214.9 mJ/cm2

60 mC/cm2

Didn’t test formulation

22.47 mJ/cm2


Significant outgassing for the e-beam experimentE-beam doesn’t predict the EUV behavior

Correlation EUV vs E-Beam: outgassing

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Greg here you have to explain the experiment.

EUV E-beam


Super Outgassing Formulations – Albany testing

Typical resists outgas 1-2 x 10-8 Torr, but these were ~50x higher – can’t use normal calibration - use the total pressure in the chamber during exposure

§ Low Ea protecting groups – AAl1 type hydrolysis –no water required

§ High Base/High PAG formulations – maximise photoproducts at moderate to high dose

§ #3 -- ECPMA/HS 50/50 – 8.5 x 10-7 Torr

§ #5 -- ECOMA/HS 40/60 – 1.6 x 10-6 Torr

§ Formulation– TPS-Tf/TBAH Thickness 150 nm

O

O

OH

O

O

OH

ECPMA/HS

ECOMA/HS


Resist Outgassing

§ Origins of Ougassed products– PAG Photoproducts– Polymer Photoproducts – side

chain scission– Polymer Acidolysis and

deprotection products – Thermal Reactions

§ Structural effects on Optics Contamination - Formation of carbon films

– Mol weight,– Empirical Formula– Sticking coefficients– Contribution to C Film


DOSE CORRELATION: E-beam vs EUV: 30 nm lines

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Can we find a general correlation between e-beam dose and EUV dose?

Very random behavior between good performance correlation and dose correlation


Dose Analysis: Contrast Curves

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Contrast curves seem to follow linear behavior y=yo+AxWith yo= 3 10A = 7 2

However previous data show the quite different results for different resists (same resin, but different PAGs)

Linear behavior but much different slope


Conclusions

§ E-beam not a substitute for EUV prediction – As demonstrated some resist well behaved in E-beam didn’t perform as well in EUV– The opposite is also true, some good performance EUV resist didn’t perform as well in e-

beam

§ E-beam value– general PAB/PEB relations– Contrast behavior– Film loss/resist shrinkage

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ADDITIONAL SLIDES

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shrinkage

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euv and electron-beam lithography performance...

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