Development Status of EUVL Blank and Substrate6 2010 International Workshop on EUV Lithography Jun /...
Transcript of Development Status of EUVL Blank and Substrate6 2010 International Workshop on EUV Lithography Jun /...
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
Development Status of
EUVL Blank and Substrate
Asahi Glass Company
Toshiyuki Uno
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
Contents
1. Introduction
2. Blank defect reduction
1. Inspection capability
2. Substrate
3. ML blank
4. Absorber
3. Integrated & Best performance of ML Blank
4. New material development
1. New capping film
2. 193nm ARC
5. Road map & Summary
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
1. Introduction
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
1-1 EUVL mask blank structure
EUVL mask blank has a stack of reflective, capping, absorber and anti-reflective layers on its front side for a patterning and a conductive layer on its back side for mask chucking.
Glass substrate
Conductive layer for
electrostatic chuck
Reflective multilayer
Capping (and/or Buffer) layer
Absorber layer
Antireflective layer
Structure of EUV mask blank
Resist film
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Material synthesis
Lapping&Polishing Lap and polish to smooth & flat
surfaces
1-2 EUVL mask blank manufacturing process
Flame hydrolysis of Si and Ti source materials to
form the Ti-doped SiO2 glass ingot
Slicing Slice the glass ingots into 6025 plates
Cleaning Remove particles and polishing slurries
Film deposition Deposit reflective, capping, absorber and ARC
films
AGC is taking care of all processes essential to EUV mask blank: LTEM material, polishing, cleaning, film deposition and resist coat.
Resist coat
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Metrology tools Pilot line
CTE
measurement
Dilatometer (ASET model)
Defect inspection Lasertec M1350A
Defect analysis SEM/EDS
Surface flatness Interferometer
Surface
roughness
AFM
Zygo Newview
EUV
reflectometer
Stand Alone
DUV~NIR
reflectometerHitachi, Shimadzu
In addition to these, we also have various kinds of defect characterization tools
(u-FTIR, u-Raman,…), film characterization tools (XRR, XRD,…) and dry etcher.
1-3 EUV mask blank pilot Line ~ Metrology tool
AGC possesses critical metrology tool sets, which make it possible to realize the total quality improvement of blanks.
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2. Blank defect reduction
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The real size of defect increases with the relative defect size (pixel) provided by the defect inspection tool (M1350A)
Pixel 3 corresponds to 34nm SEVD (Sphere equivalent volume diameter), Pixel 8 to 56nm SEVD
2-1 Inspection and size of native defects
Depth or
Height
SEVD
Full width
Native defect Equiv. Sphere
d
0
50
100
150
200
0 5 10 15 20
Actu
al defe
ct siz
e
(nm
)
Relative defect size (M1350A pixel)
Volume by AFM
M1350A pixel vs real defect sizeTypical defect map and histogram
of M1350A inspection
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
We have been optimizing the polishing conditions by changing processes parameters, conditioning and materials to reduce the substrate pit.
The results shown here were ML pit count & relative yield (10Q1-2 = 100) of QZ test plates. We demonstrated 0 pit @56nm SEVD ( sphere eqiv. volume diameter)
2-1-1 Blank defect reduction ~ Substrate pit ~
0 0
48
100
0
47
64
100
0
20
40
60
80
100
Rel
ativ
e Y
ield
0 pit yield @ 56nm SEVD
<=15 pit yield @ 34nm SEVD
08Q4 09Q1 09Q3 10Q1-2
2 1 0 0
16
8 97
0
5
10
15
20
ML p
it c
ount
Best pit count @ 56nm SEVD
Best pit count @ 34nm SEVD
08Q4 09Q1 09Q3 10Q1-2
ML Pit defect count trend ML Pit defect yield trend
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
The average defects counts on LTEM substrates @ p1+ and relative yield of 0 unremoval particle were shown below.
To reduce un-removal particles, we installed the new intermediate cleaning tool in 09Q3. Consequently, the number of un-removal particles on LTEM substrate has been drastically decreased.
We expect that “added particle” will be decreased further by optimizing the final cleaning processes.
2-1-2 Blank defect reduction ~Substrate particle ~
Average defect counts of LTEM substrates
0
2
4
6
8
10
12
14
16
18
08H1 08H2 09H1 09H2 10Q2
Ave
rage
de
fect
co
un
t@p
1+
added particle
unremoval particle
Pit
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2-2 Blnak defect reduction ~ LTEM-ML blank ~
Target
This is the best defect trend of the LTEM-ML blank where
the substrate flatness is <150mm.
Best defect trend of LTEM-ML blank
(Lasertec M1350A inspection)
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We have improved the absorber adder defect performance.
• The adder defect count has been decreased by optimizing
coating equipment.
• We have obtained several plates with no adder defect
larger than 100nm SEVD.
Adder defect map
& Histogram
2-3 Blank defect reduction ~ Absorber ~
100nm SEVD
Average adder defect counts
09H2 10H1
~200nm SEVD
89nm SEVD
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3. Integrated & Best performances
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Structure
CrN/LTEM/ML/Ru
CTE of LTEM
Mean CTE -3.5 ppb/K
CTE variation (PV) 1.7 ppb/K
Substrate flatness
front 89 nm
back 76 nm
Blank Flatness(Bow) 0.38 um
Reflectivity
Peak R 66.2 %
R range(Abs.) 0.3 %
centroid l 13.535 nm
l range 0.026 nm
3-1 Integrated performance of LTEM-ML blank
0.12cm-2 @ >34nm SEVD
Defect map and histogram
0.05 cm-2 @ >56nm SEVD
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Requirements
(SEMI P37,38) current best
Substrate
CTE mean +/-5 ppb/K 0 ppb/K
CTE variation +/-3 ppb/K +/- 1ppb/K
flatness (front) <30 nm 38 nm on LTEM
flatness (back) <30 nm 48 nm on LTEM
HSFR (RMS) <0.15 nm <0.10 nm
ML/Capping
Defect (ML/Cap)0.00 c/cm2
@30 nm0.04@56nm (SEVD)
Peak Reflectivity >67 % 67.1
Mean Centroid λ n/a 0 to target
FWHM >0.50 nm >0.50 nm
3-2 Best performance of LTEM -ML BlankWe can mostly achieve the requirements other than defect.
Green : met SEMI spec. yellow : TBD Red : need development
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4-1. New capping film
AGC has developed the new Ru film, which showed better
chemical & thermal durabilities than the conventional (current) Ru film.
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4-1-1 EUV reflectivity change upon O3-DIW cleaning
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
12.5 13.0 13.5 14.0 14.5
Wavelength (nm)
EU
V R
efle
ctivity
as-depo
post-cleaning
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
12.5 13.0 13.5 14.0 14.5
Wavelength (nm)
EU
V R
efle
ctivity
as-depo
post-cleaning
66.6 %
66.0 %
-0.6 %
66.8 %
63.7 %
-3.1 %
Fig. EUV reflectivity spectrum before and after O3-DIW cleaning (~30ppm x 10min)
Conventional Ru
(~2.5nm)
New Ru (~2.5nm)
The new Ru capped ML showed the better durability upon the wet cleaning using
ozonated water (~30ppm) than the conventional Ru (2.5nm).
In the new Ru capped ML blank, the reflectivity drop was <1% and the reflectivity after
cleaning was >65%. This effect of the new Ru has been confirmed repeatedly.
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No clear difference of roughness was observed in both new Ru and
conventional Ru films.
4-1-2 Roughness change upon O3-DIW cleaning
Conventional Ru (~2.5nm)New Ru (~2.5nm)
As-depo
Post-Cleaning
Rms=0.94nm Rms=1.02nm
Rms=0.82nm Rms=0.99nm
Fig. Surface roughness of
QZ/ML/Ru
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4-1-3 EUV reflectivity change upon thermal treatment
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0.1
0.2
0.3
0.4
0.5
0.6
0.7
12.5 13.0 13.5 14.0 14.5
Wavelength (nm)
EU
V R
efle
ctivity
as-depo
post-bake
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
12.5 13.0 13.5 14.0 14.5
Wavelength (nm)
EU
V R
efle
ctivity
as-depo
post-bake
Conventional Ru (~2.5nm)New Ru (~2.5nm)
66.6 %
62.6 %
-4.0 %
66.4 %
58.1 %
-8.5 %
Fig. EUV reflectivity spectrum before and after the thermal annealing (210oCx10min, in air)
The new Ru film also showed the better thermal durability in air than the
conventional Ru film.
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4-2 193nm ARC
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2010 International Workshop on EUV Lithography Jun / 21-25 / 2010
Standard Candidate 1 Candidate 2
Structure
R%@193nm > 20% < 7% < 7%
Feature ARC for 257nnmThinner ARC
Lower Etching Rate
Thicker ARC
Higher Etching Rate
4-2-1 193nm ARC candidate material
ML
TaON ARC 7nm
Ru
TaN Absorber
ML
HfON ARC ~10nm
Ru
TaN Absorber
ML
SiN ARC ~10nm
Ru
TaN Absorber
TaON ARC ~1nm
ML
Ru
TaN Absorber
TaON ARC 7nm
ML
TaON ARC 7nm
Ru
TaN Absorber
ML
TaON ARC 7nm
Ru
TaN Absorber
ML
Ru
TaN Absorber
ARC-1 8nm
ML
TaON ARC 7nm
Ru
TaN Absorber
ML
Ru
TaN Absorber
ARC-2 12nm
AGC released the blanks with 2 types of New ARC layers for 193nm mask inspection.
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4-2-2 Candidate 1 ~DUV performances~
This the measurement result of DUV spectra of TaN(51nm)/ARC-1(6~10nm). The samples more than 8nmthickness shown here had <7% reflectivity at 193nm.
Fig. DUV reflectivity spectra
0
5
10
15
20
25
30
190 210 230 250 270 290
wavelength (nm)
Re
flectiv
ity (
%)
TaN/HfON=51/6nm
TaN/HfON=51/8nm
TaN/HfON=51/10nm
193nm
257nm
TaN(51nm)/ARC-1(6nm)
TaN(51nm)/ARC-1(8nm)
TaN(51nm)/ARC-1(10nm)
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0
5
10
15
20
25
30
190 210 230 250 270 290
Re
fle
ctivity (
%)
wavelength (nm)
4-2-3 Candidate 2 ~DUV performances~
This is the measurement result of DUV spectra of TaN(51nm)/ARC-2(11~13nm). All three samples shown here had <7% reflectivity at 193nm.Absorber with ARC-2 can be etched by one-step with Cl2 chemical.
Fig. DUV reflectivity spectra
193nm
257nm
TaN(51nm)/ARC-2 (11nm)
TaN(51nm)/ARC-2(12nm)
TaN(51nm)/ARC-2(13nm)
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4-2-4 Durability to wet cleaning & thermal
Durability performances for 60min were investigated .Both materials candidates showed no degradation upon H2SO4, SC1 and 150oC thermal
annealing for 60min.
0
1
2
H2SO4(98%) SC1 Heat(150C)
Re
fle
ctivity C
ha
ng
e (
%)
TaN/ TaON (Standard) @ 257nm
TaN/ SiN/TaON @ 200nm
TaN/ HfON @ 200nm
Fig. Durability performances : DUV bottom reflectivity changes
Durability Test Condition
SC1 : 40C 60min Dip
H2SO4(98%) : 40C 60min Dip
Heat: 150C 60min in Air Better
WorseTaN/TaON (standard) @ 257nm
TaN/ ARC-2 @ 200nm
TaN/ ARC-1 @200nm
0
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5. Roadmap of EUVL Blank development
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5-1 Roadmap
2009 2010 2011 2012 2013 2014
H1 H2 H1 H2 H1 H2 H1 H2 H1 H2 H1 H2
1st generationSubstrate : LTEM w/zero CTE@22oC
(Flatness<100nm)
Capping : Ru or New Ru
Absorber : TaN (51nm or 77nm)
ARC : TaON or 193nm ARC
2nd generationSubstrate : LTEM w/ zero CTE
@ high temperature?
Capping : New Ru
Absorber : New material (30~40nm)
ARC : TaON
or 193nm ARC
or no ARC
HVMProcess development
at Pilot line
HVMProcess developmentMaterial
development
Any needs for LTEM w/ zero CTE at elevated temperature?
AGC is carrying out the process development of 1st generation blank. AGC is also
developing the material of 2nd generation blank which will be suitable for 16nm hp and off-
axis illumination.
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5-2 Summary
The tool upgrade and improvement of polishing and
intermediate cleaning were carried out, which resulted in the
significant improvement of substrate defect performance
and yield.
Continuous improvement and integration are in progress
at AGC and single defect counts on ML blank @ 54nm
SEVD has been achieved.
AGC successfully introduced New-Ru capping film and
193nm ARC to the industry.