compact euv source for metrology and inspection · -5 0 5 10 0 5000 10000 15000 20000 nits ]...

© Fraunhofer ILT

Klaus Bergmann, Jochen Vieker, Alexander von Wezyk

2015 EUV Source Workshop, 10.11.2015, Dublin

Compact EUV Source for Metrology and

Inspection

© Fraunhofer ILT

Overview

Introduction

Xenon based EUV Source FS5420

Consideration on 6.x nm emission

Recent progress on lifetime and power scaling

Dose control of brilliance

© Fraunhofer ILT

v:<a11.2015.tagung.euvl2015.dublin>S32_dublin2015.pptx

EUV Source Activities at Fraunhofer ILT

Tin vacuum arcHCT pinch plasma

Water window microscopy (2.9 nm)

Nano patterning

Coherent diffraction imaging

EUV microscopy

Photo electron spectroscopy

Sources for Aachen University

Material/EUV-DPP-DEMO-v6.wmv

Material/EUV-DPP-DEMO-v6.wmv

© Fraunhofer ILT


Hollow Cathode triggered Pinch Plasma

trigger unit

power supply

trigger-

electrode

V

pulse train (1.5 kHz) discharge

V

V - triggerV - capacity

500 ns

anode

cathode

© Fraunhofer ILT


Fraunhofer ILT Source : FS5420

EUV source including power supply, control unit & chillers

Standard Mode

Inband Power : > 20 W/2psr

EUV pulse energy : 2,2 mJ/sr

typ. repetition rate : 1500 Hz

ave. peak brightness : 8 W/mm2sr

High Pulse Energy Mode

Inband Power : < 10 W/2psr

EUV pulse energy : > 4,0 mJ/sr

typ. repetition rate : < 400 Hz

© Fraunhofer ILT


HMI - Software

repetition rate and pulse energyselectable in pre-defined ranges

gas flow automatically adjustedaccording breakdown delay

option for soft ramping up and down of input power

display of measured frequency and power

measuring and display of missing pulses (Quality Factor)

option for EUV power monitoring and dose-control

fully accessible via Ethernet / Fieldbus

© Fraunhofer ILT


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INT

EN

SIT

Y [

arb

. un

its ]

DISTANCE [ mm ]

linescan axial direction

p:<euc_china.laborbuch.bergmann.2015.160115>linescans_FS5420_24°_5J.opj

Emission Characteristics

EUV source dimensions:diameter (FWHM) : < 300 µmlength (FHWM) : ~4 mm

stability of diameter : ~ 4 %

spatial stability : < 7 µm

pulse duration : 50 – 100 ns

power stability : 1-3 %(100 pulses moving averageover 10 minutes without dose control)

Typical FS5420 emission spectrum

Axial and radial emission profile

10 11 12 13 14 15 16 17 180

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J/2psr

nm

puls

e ]

WAVELENGTH [ nm ]

v:<a11.2015.tagung.euvl2015.dublin.material>emission spektrum FS5420.opj

© Fraunhofer ILT


Emission around 6.x nm

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70

Krypton (4,4 J)

RA

DIA

NC

E [

mJ/(

2p s

r nm

) ]

WAVELENGTH [ nm ]

p:<be_euv_6x.laborbuch.bergmann.2014.140206>absolute_estimation_6px.opj

Contributions from 4d-4f transitions around KrX

Emission between 6-7 nm at 4,4 kWinput power : ~ 15W/2psr

Suitable for irradiation damage studiesor optics characterization

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INT

EN

SIT

Y [ a

rb. units ]

RADIUS [ µm ]

Flatfield spectrum wavelength

radius

diameter (FWHM)~ 200 µm

Line scan+ de-convolution

© Fraunhofer ILT


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EU

V-P

OW

ER

[ W

/(2psr

2%

b.w

.) ]

TIME [ s ]

Power Scaling: FS5420 in 40 W - Operation

average input power:

13 kW

repetition rate:

2500 Hz

peak brightness:

~12 W/mm2sr

pulse-to-pulse standard deviation:

6,8 % 0 10 20 30 40 50 60

0

50

100

150

200

FR

EQ

UE

NC

Y [

arb

. u

nits ]

POWER [ W/2psr ]

EUV inband power during a 30 min run

© Fraunhofer ILT


Power Scaling: FS5420 in 55 W - Operation

EUV inband power during a 30 min run

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80E

UV

PO

WE

R [

W/2psr

]

TIME [ min ]

p:<euv_china.laborbuch.bergmann.2015.150120>50W-40min.opj

2.0 kHz, 11 kW

© Fraunhofer ILT


Source Development Aspects

Pinch Plasma

Sputtering dueto pinch plasma

Cathode spots

better understanding of origin of decreaseof CE and performance during operation

reduction of erosion by choosing sputter resistive material

current achievement for the cathode: >800 Mshot and still running

Comparison of Mo and W-based cathode aftersame number of Mshots

© Fraunhofer ILT


Advanced Triggering

Conventional triggering

time

voltage

charging

discharge

cathode voltagetrigger electrode voltage

More sophisticated Utrigger(t) attrigger electrode

Use of additional potential atintermediate electrode UIP(t)

Advanced triggering

UIP(t)

© Fraunhofer ILT


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0,1

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0,8

CE

[ %

/2psr

]

XENON FLOW [ sccm ]

Former process window

Increase of operation window

On-Axis PinholecameraRFWHM=250µmXe-flow 25 sccm

larger process window for Xe- flow due to advanced triggering

higher tolerance towards electrode erosion (tested electrodes had >150 Mshot)

higher CE ( ~0.7 %) at lower gas flows achievable

13.5 nm inband power at 6 kW input:

~ 40 W/(2psr)

13.5 nm inband brightness at 6 kW input:

~ 12 W/(mm 2sr)

© Fraunhofer ILT


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CE

[ %

/2psr

]

# PULSES [ MShot ]

v:<a11.2015.tagung.euvl2015.dublin.material>vgl_intermediateplates.opj

Increase of maintenance interval

wear of IP (Intermediate Plate) is mainly determining the source performance

Xe flow increases with wear of IP

higher flow lead to lower CE and reduces the working range

advanced triggering allows operation at lower Xe flow with increase of CE

1 Gshot maintenance interval with advanced trigger expected

Advanced triggerState-of-the art

Comparison of IP’s with different lifetime

IntermediatePlate (IP)

less erosive material for IP

© Fraunhofer ILT


Demonstration of Dose Control of Inband-Power

measurement of inband EUV for each pulse

assumption of linear behavior of EUV pulse energy with input pulse energy

variation of input pulse energy for each pulse

expected dose stability within window of N pulses (s: standard deviation)

without dose control : s / √Nwith dose control : s / N

Ref. : Pankert et al., SPIE 2005

Dose control at Philips-EUV Xenon source for ASML alpha-tool

© Fraunhofer ILT


Dose Control of Brilliance : Task

Potential improvement of 1/N½ allows for relaxed conditions for source stability sB

Look for suitable parameter with high correlation, r, with source brilliance

Built up of pulse-to-pulse metrology for this parameter(e.g. total inband photon flux)

Optical System

Intensity profileat source

Intensity profileat focal plane

sB sB /Nachievable deviation:

(N pulses integral)

© Fraunhofer ILT


Dose Control of Brilliance : Requirement on Correlation

r = 0.3 r = 0.7 r = 1.0

Simulation for Gaussian Distributions <x>, <y>with s = 10 % each and average values of 1.0

x measured parameter, e.g. inband photon flux

y controlled parameter, i.e., source brilliance

Integration over N = 100 pulses

improved dose stability requires r > 0.5

without dose control

with dose control

100 102 10498

100 102 10498 100 10298 100 100.599.5

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© Fraunhofer ILT


Dose Control of Brilliance : Correlation Parameter

Proof of concept experiment at 1 kHz & 4 J input powerFast EUV-inband Cameras at 2,5 Hz pulse picking

Metrology:Camera on-axisCamera off-axisEUV Energy Monitor off axis

Evaluation at fixed pixel-position

High sensitivity setup without Zr-Filter at off-axis camera-> some visible light may still be interfering

High Correlation Coefficient r>0,85 for Spot with 60 µm diameter

Single-shot Camera images of pinch:On-Axis

Off-Axis

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1,0

1,2

Corr

ela

tion C

oeffic

ient

On-Axis Radius of integration [µm]

High sensitivity

simple 2-Camera Setup

EUV Energy Monitor

P:\EB_XUVQUELLE\Treffen_Tagungen\Zeiss_151019

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Peak B

rightn

ess [a.u

.]

Electrical Pulseenergy [J]

M:\A11\2012\MESSDATEN\EUV\Xenon\20120914

Linear Brightness – Pulse energy dependence allowsactive control of dose collected from small NA

© Fraunhofer ILT


Summary

New generation FS5420 EUV source is available at Fraunhofer ILT

Improvements in operation by software, e.g. error detection and automatic adjustment of operation parameters

Ongoing basics investigations on lifetime and power scaling

Major improvements have been demonstrated in key experiments by means of advanced triggering

Next generation FS5440 – 40 W EUV source in development: Combining long-life electrodes with high CE of new trigger system

compact euv source for metrology and inspection · -5 0 5 10 0 5000 10000 15000 20000 nits ]...

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