Contamination Removal of EUVL masks and optics using 13.5-nm...
Transcript of Contamination Removal of EUVL masks and optics using 13.5-nm...
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Contamination Removal of EUVL masks and optics using
13.5-nm and 172-nm radiation
Takeo Watanabe, Kazuhiro Takeo Watanabe, Kazuhiro HamamotoHamamoto and and HirooHiroo KinoshitaKinoshita
University of HyogoUniversity of Hyogo
IEUVI Resist & Contamination TWG Oct.19, 2006 in Barcelona
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Method of contamination removal
(1) Cleaning of EUVL imaging optics(The optics used for EUVL has been aligned
in high accuracy. So the cleaning of imaging opticsrequires in-situ process.)
⇒ In-situ contamination removal by synchrotron radiation without heating
(2) Cleaning of EUVL masks(Both large cleaning area and high speed are required.)
⇒ Contamination removal by 172-nm-wavelength.
Evaluation between before and after removal・Contamination thickness → Optical thickness measuring system・Surface roughness → AFM・Reflectivity → Reflectometer (NewSUBARU BL-10)
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Online contamination removalby a wavelength of 13.5 nm
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20 40 60 80 10010-8
10-7
10-6
10-5
10-4
10-3
Parti
al p
ress
ure
(Pa)
Mass number
H2O
CO2CxHy
N2
Partial pressure in ETS-1
Total pressure: 1×10-5 Pa
Contamination adhesion in ETS-1 exposure system
Sample of the multilayer isset on the mask stage, andEUV is irradiated.
M2M1 M3
Wafer
Mask
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Deposition rate: 7.5 nm/hr (0.125 nm/min)
Thickness of contamination
Electron beam current: 200 mA
0 100 200 300 400 5000
10
20
30
40
50
60
70Th
ickn
ess
of c
onta
min
atio
n (n
m)
Irradiation time (min.)
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Reflectivity of multilayer
Multilayer reflectivity of 10% decreasedby 4 hours irradiation
0 100 200 300 400 5000.3
0.4
0.5
0.6
0.7R
efle
ctiv
ity
Irradiation time (min.)
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Surface roughness of multilayer
0 100 200 300 400 5000.10
0.15
0.20
0.25
0.30
0.35
0.40S
urfa
ce ro
ughn
ess
(nm
)
Irradiation time (min.)
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C
O
Ta
Pho
toel
ectro
n in
tens
ity fo
r C
, O, S
i (cp
s. e
V) Photoelectron intensity for
Ta (cps. eV)
Sputtering time (min.)
AES spectrum of contamination of mask
The ratio of C to O is 96:4
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Experimental setup of SR cleaning
Contaminationtesting chamber
Storagering
M1 mirror
M2 mirrorM3 mirror(Branch)
ETS-1
adding O2 during
SR irradiation
Back pressure:5.0×10-5 Pa
pressure:5.0×10-2 Pa
Incident angle
TMP
Photodiode (GaAsP)
SR
10°
Mask sampleOxygen
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Experimental results
0.85
0.9
0.95
1
1.05
1.1
1.15
0 10 20 30 40 50 60
Time (min.)
Normalized reflectivity
Normalized storage ring current Pressure: 5.0×10-2 Pa
Electron beam current: 130 mA
Irradiation: 7 hr
Before cleaning After cleaning
Contamination of 0.1-µm-thick was removed.
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0 1x106 2x106 3x106 4x106 5x106 6x106 7x106 8x1060
20
40
60
80
100
120
140
160
180
200
Red
uctio
n in
thic
knes
s (n
m)
Exposure dose (mAs)
Reduction of contamination thickness
Removal rate:0.24 nm/min
7 hr
Electron beam current: 130 mA
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Before cleaning
A
D
BC
E
Reflectivity of multilayer (measurement: NS-BL10)
After cleaning
0
0.2
0.4
0.6
12.0 13.0 14.0 15.0
Wavelength (nm)
Ref
lect
ivity ED
CB
A0
0.2
0.4
0.6
12.0 13.0 14.0 15.0
Wavelength (nm)
Ref
lect
ivity
absorber absorber
multilayermultilayer
contamination absorber
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Offline contamination removalby a wavelength of 172 nm
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Mask cleaning using 172 nm-excimer VUV/O3
⇒ A high density active oxygen species can be generated.
The absorption coefficient to the oxygen molecule at the wavelengthof 172 nm is 20 times larger than that at the wavelength of 185 nm of the low-pressure mercury lamp.
172 nmCOx, H2,CHz,H2O,…
oxygen(O2)
CxHy
Mo/Si
ozone(O3)
Active oxygen species(O*)
contamination
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Experimental setup of 172 nm cleaning
Intensity 20 mW/cm2Distance 1 mmSample size 8-inchTemperature 25℃Environment in the air / in O2-rich vacuum
Stage
1mm
172 nm excimer lamp
O2-rich vacuum environment:The initial back pressure of the chamber was 500 Pa by scroll pump, and an O2 flow kept the pressure at 2×103 Pa.
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0 10 20 30 400
5
10
15
20
25
30R
emov
al th
ickn
ess
(nm
)
Cleaning time (min)
Results of mask cleaning using 172 nm-excimer lamp(1) Reduction of contamination thickness
in vacuumrate: 2 nm/min.
in the airrate: 0.53 nm/min.
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Results of mask cleaning using 172 nm-excimer lamp(2) Reflectivity of multilayer
0%
10%
20%
30%
40%
50%
60%
70%
12.0 12.5 13.0 13.5 14.0 14.5 15.0Wavelength (nm)
Ref
lect
ivity Before cleaning
After cleaning
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Summary
(1) From the result of AES, it has been understood that the element of contamination is almost carbon.
(2) The effectiveness of the contamination removal for EUVL imaging optics using both in-situ and non-heating method by EUV irradiation in the oxygen atmosphere is confirmed.
(3) The effectiveness of the contamination removal for the finished EUVL mask in off-line process using the 172 nm-excimer lamp in the O2-rich vacuum atmosphere at the room temperature is confirmed.
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Thank you for your attention!!
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Outgassing Measurementin University of Hyogo
-Short summary-
Takeo Watanabe, Hiroo KinoshitaUniversity of Hyogo
IEUVI Resist & Contamination TWG Oct.19, 2006 in Barcelona
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Sample
PC controlled fast speed shutter(∆∆∆∆t=11 ms)Mo/Si MLs
Concave Mirror
High-sensitive ion counting typeQ-massspectrometer
Mo/Si MLs Two Plane Mirrors
SR
Setup of novel resist evaluation system
Simulating six-mirror optics
Practical exposure spectrum
1) Measurements of sensitivity2) Outgas characteristics3) Chemical reaction analysis
Distance 30 mm
Model HAL/3F/PIC 501 RC, Hiden Analytical, Ltd.
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Setup of novel resist evaluation system
Loadlock chamberTMP 300L/s
Sample
Shutterchamber
SR
Sample chamberTMP 300L/s
Sample insertion rod
Gate valve
Gate valve
Gate valve
Mirror chamberTMP 700L/s
Differential pumping
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6.7×1016
35-200 amu4.5×1013
35-200 amu9.4×1014
35-200 amu
2.9×10173.4×1014
0.27 mW/cm2
1-200 amu
7.1×1015SynchrotronOnline QMS
Univ. of Hyogo
3.1×101635-200 amuExcluding 44 amu
2.1×101335-200 amuExcluding 44 amu
4.3×101435-200 amuExcluding 44 amu
8.3×10155×1013
1 mW/cm2
??-??? amu
2.8×1014Stand-alonesourceOnline QMS
BOC Edwards
5.7×10154.5×1012
0.13 mW/cm2
1-200 amu
1.9×1014SynchrotronOnline QMS
ASET
1.1×10152.6×1012
0.37 mW/cm2
35-435 amu
3.9×1013SynchrotronGC/MS
SEMATECH
1.3×10137.3×109
0.09 mW/cm24.37×1011Synchrotron
GC/MSIntel
Molecules/cm2/s@each intensity condition
Molecules/cm2
@5.6 mJ/cm2 dose
Estimate RateMolecules/cm2/s@Prod. Tool(0.4 W/cm2)
ResultsMethodInstitute
By Takeo Watanabe, Univ. of Hyogo 2006 Oct 19