optics for euv lithographyeuvlsymposium.lbl.gov/pdf/2005/pres/39 3-op-12 kuerz.pdf · lithography...

Lithography Optics Division

Optics for EUV Lithography

Peter Kürz, Thure Böhm, Stephan Müllender, Wolfgang Bollinger, Manfred Dahl, Martin

Lowisch, Christian Münster, Frank Rohmund, Thomas Stein, Erik Louis, Fred Bijkerk


Design example

A collector module has been qualifed and is usedto test the illuminator at wavelength.

The early projection opticsis in the qualification phase

EUV alpha demo tool: Status at Zeiss

Key specificationsλ 13.5 nm NA 0.25Resolution 50 nmfield 26x33 mm2

Magnification 4x

One illuminator hasbeen qualified

and the secondis in process

N. Harned et al: this conference


Illuminator

All mirrors have beenfabricated and coated

EUV qualification has beenfinished

System fully assembledand aligned


EUV qualification: hardware

@ λ illuminator metrology tool

„reticle stage“ for metrology


Camera

Lens

Metrology Reticle

Scintillator

Vacuum window

EUV Radiation

Scales, Markers

Reticle Stage

Metrology

EUV qualification: Results (1)

Magenta lines: circles around optical axis

Stitching of 3 Images

Ring field measurement


EUV qualification: concept for field and pupil qualification

Camera

Lens

Metroloty Reticle, Pinhole

Telecentricity Screen

Vacuum window

Reticle Stage

Setup for Pupil Qualification

Metrology-Reticle

Slit + Filter +EUV-Photodiode Field

Scanning field with slit EUV photodiode. Integration in y-direction.

Setup for Field Qualification


Uniformity EUVL-Source+SoCoMo+IlluMo, 21. Sept. 2005, 09:40

0.95

0.96

0.97

0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

x @ Reticle (mm)

Nor

mal

ized

Inte

nsity

measured uniformity at recticleplane < 2.5 %

Pupil: Telecentricity < 0.5%Ellipticity < 10% (calculated value for Sn source)

EUV qualification: Results (2)


Projection Optics Box

reticle

wafer

Status:• all mirrors fabricated and coated

• assembly complete

• system metrology has been set up

• the POBox is in the qualification phase

Design example


Status POBox: System Metrology

POBox test lens on system inteferometer

System Metrology for POBox alignment/qualification has been set up


Early POBox: Alignment Status

Status today: - POBox is in the final qualification phase

Performance prediction:- 50 nm dense lines can be printed with the early POBox

248nm illumination (*converted by phosphor screen): image of the reticle mask in the wafer plane

July 22: first light


2D-isotropic PSD

Errors … causes ….:

Challenge: reach about 0.2 nm rms for Figure, MSFR and HSFR simultaneously

Lateral Frequency [μm-1]

figure aberrations

Figure

MSFR Flare, contrast

in field of view scattering

MSFR

Optics Technology (1): Fabrication of EUV mirrors

HSFR reflectivity

HSFR


Main challenge: flare reduction

( )2

24 ⎟⎟⎠

⎞⎜⎜⎝

⎛=

λπ surfacerms

TIS

Due to the very small wavelength EUV imaging is sensitive to scatter !!!

Total integrated scatter

2surfacemirrors rmsnTIS ⋅∝

Reduction of mid spatial frequency rms is essential to reduce the flare level


flare reduces overlapof process windowsdue to dose offsets

proximity effects in dependence of thelocal reticletransmission

largest impact of flare on isolatedfeatures on bright-field masks

sensitivity of CD to dose errorsbecomes larger

Dose-to-targetchange

No flareWith flare

Main challenge: flare reduction

CD

Intensity cross-section


0

5

10

15

20

25

early POB AD 1 AD 2 productiontool

flare

[%]

Flare roadmap

target


MSFR at fine figuring processes

0.15

0.17

0.19

0.21

0.23

0.25

0 20 40 60 80 100 120

relative material removal / %

MSFR

/ %

EUV mirror fabrication: Process development

Critical process step: Fine Figuring

Relative material removal: 100% is representative for reaching figure spec on alphademo tool mirror

technology to reach MSFR of ≤ 0.2 nm rms on alpha tool mirrorshas been established (16% flare tool)

Mirror for 16% flare tool: M1 - 0.19 nm

MSFR = 0.2 nm rmsnm


Learning curve – mid spatial frequency roughness

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

MSF

R [n

m rm

s](e

valu

ated

over

4.6

deca

des)

test mirror

Set 3

Set 1

Set 2

test mirror(MSFR opt.)

MET AD

early POBmirrors

M116% flare

production tool target

23 % flare

6% flare


Optics Technoloy (2): Coatings

Recent developmentat FOM

xy

A complete set of alpha tool mirrorshas been coated at FOM…

… and ZeissNew capping layer:

reflectance 68.5%comparable to uncapped multilayer

New capping layer:reflectance 68.5%comparable to uncapped multilayer

0%

10%

20%

30%

40%

50%

60%

70%

12.8 13 13.2 13.4 13.6 13.8 14

Wavelength [nm]

Ref

lect

ance

@ 1

.5 º

E. Louis et al: this conference


• alpha tool program is progressing:• illuminator

• alignment and EUV qualification has been finished• POBox

• all mirrors have been fabricated and coated• system metrology for the POBox is operational• the POBox has been assembled and is in the qualification phase

• technology development• 16% flare capability has been demonstrated on AD tool mirrors• new high reflectivity cap layer has been developed

Summary

EUV Optical Technology at Carl Zeiss SMT AG: has reached α-tool specsis progressing towards production tool capability


Thanks to a huge team effort at…

• FOM-Rijnhuizen• TNO TPD• PTB-BESSY• Philips• The teams at ASML and Zeiss• …and many others

Part of this work was supported by:

Acknowledgment

Bundesministerum für Bildung und Forschung Projekt „Grundlagen der EUV-Lithographie“ 13N8088, MEDEA Project „EXTATIC“ and European Commission Project 507754 „More Moore“

optics for euv lithographyeuvlsymposium.lbl.gov/pdf/2005/pres/39 3-op-12 kuerz.pdf · lithography...

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