Assessment of AIMS™ EUV and SHARP actinic wavelength mask defect review tools for the evaluation of blank defect printability Erik Verduijn, Erik Hosler, Pawitter Mangat, Obert Wood Globalfoundries, Inc. Malta, NY 12020 USA
Renzo Capelli, Sascha Perlitz, Krister Magnusson, Markus Weiss, Dirk Hellweg Carl Zeiss SMT GmbH, Rudolf-Eber-Straße 2, 73447 Oberkochen, Germany
Vibhu Jindal SUNY Poly SEMATECH, 257 Fuller Road, Albany, NY 12203, U.S.A.
Markus P. Benk, Antoine Wojdyla, Kenneth A. Goldberg Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
EUV Symposium, Maastricht NL, October 5-7, 2015
Motivation
• Defect-free EUV masks are required, especially for logic devices.
– Optical inspection and wafer printability confirmation are not viable options for HVM
– Pawitter Mangat et al. PMJ 2015: “Having a bright-field actinic defect review tool will enable defect-free printability in HVM with confidence”
• Here, we compare the performance of SEMATECH’s SHARP actinic microscope with the AIMS™ EUV commercial actinic review tool being developed by Carl Zeiss SMT
• Both AIMS™ EUV and SHARP are actinic tools
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Blank Defect Review Procedure
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AIMS™ Review SHARP
Review
Litho
NA 0.33 0.25
0.33
0.25
0.33
Illumination Annular Conventional
Annular
Conventional
sin–sout 0.2–0.9 0.81
0.35–0.88
0.81
Blank inspection
(LT1350 & DFX40)
Mask fabrication
inspection (KT 6xx) & SEM review
Wafer exposure (NXE3100/3300)
Mask defect actinic review AIMS™
& SHARP
Correlation Analysis
Wafer SEM review
(KT eDR7100)
Use
bla
nk in
sp
ectio
n
de
fect c
oo
rdin
ate
s
Wafer print results shown for IMEC NA 0.25 NXE:3100 0.33 NA NXE:3300 exposures show equivalent defect detection results to this study
Shown for this study
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AIMS™ EUV actinic mask review tool
Performance Specifications
Target node 7nm logic (16nm hp)
Scanner emulation Up to 0.33 NA
CD Reproducibility ≤1.5 nm (3σ, mask level)
Run Rate standard
7 focus planes per site
≥ 27.5/hr
≥ 51/hr
> 38.5% pupil fill
> 77% pupil fill
Run Rate fast mode*
7 focus planes per site
*CD-repro = 1.8 nm (3σ)
≥ 55/hr >38.5% pupil fill
Illumination conditions available on prototype:
AIMS™ EUV prototype
Mirror optics based actinic mask defect aerial imaging
EUV camera field of view: 8x8 um (mask level)
NA 0.33 scanner illumination & projection emulation
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SHARP Actinic Review Tool
8 sites/h
σ
z
13.5 nm
l T
0.25 0.33 0.35 0.42 0.50 0.625
NA 0.55/0.275 (4x)
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Mask Layout
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• GREMLIN4-LT mask (64P L/S)
L/S dies
Each die subdivided
into 64nm P H+V
Programmed
defect dies
Fill area
between dies
Large area ML/Ru-pad dies
for AFM roughness study
Outside pattern area GLOBALFOUNDRIES Public
Blank Defect Review Locations
7
-76000
0
76000
-76000 0 76000
51 67%
1 1%
3 4%
2 3%
19 25%
Blank Defect Distribution
In L/S area In programmed defect area
In fill area In Ru-pad area
Outside pattern area
BI: 76 blank defects total, post Ru Deposition
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67%
1%
4%
3%
25%
Blank Defect Distribution
Inside pattened L/S area
In programmed defect area
In fill area
In Ru-pad area
Outside patetrn area
Example Defect Types
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Large-area L/S defect Bridge L/S defect Necking L/S defect
EUV absorbing defect in absorber area
EUV absorbing defect in reflecting ML/Ru
EUV absorbing defect in reflecting ML/Ru
Blank defect in pr. defect area not found
Shown for AIMS™
EUV absorbing defect in L/S
ID14
ID12
ID46
ID03 ID20 ID61
More EUV reflecting
Less EUV reflecting
2 μm details GLOBALFOUNDRIES Public
SHARP Rev.
AIMS™ Rev.
Wafer Rev.
29
4
2
Defect Review Comparison in L/S Area
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AIMS™ SHARP WAFER
Necking None Necking
Necking None Necking
Necking None Necking
Necking None Necking
Necking None None
Necking None None
Necking Necking None
0
0
1
0
• 64 % (33 /51) blank defects in L/S area are printing
– 100% (33/33) of these are found by AIMS™
– 88% (29/33) of these are found by SHARP
– 88% (29/33) of these are found by AIMS™ and SHARP
– AIMS™ finds all defects found on wafer and by SHARP
All non-commonality in necking L/S defects
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Defects in L/S Area: Large-Area Defects
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All large area blank defects found by AIMS™ and SHARP review (6/6)
Excellent correlation between AIMS™, SHARP & wafer print
Multilayer damage more visible with actinic review than mask SEM
Actinic AIMS™
ID03
ID04
Actinic SHARP
ID11-13-6
ID11-13-08
Wafer SEM
ID03
ID04
ID57
Mask SEM
ID57
2 μm details GLOBALFOUNDRIES Public
Defects in L/S Area: Bridging Defects
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All blank defects printing as bridges
were found by AIMS™ and SHARP,
also as bridges (13/13)
AIMS™
ID20
ID40
SHARP
ID11-13-22
ID11-13-30
Wafer
ID18
ID36
Limit case of bridging
2 μm details GLOBALFOUNDRIES Public
Defects in L/S Area: Necking Defects
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100% of defects printing as necking defects
found by AIMS™, (14/14)
71% of defects printing as necking defects
found by SHARP, (10/14)
AIMS™
ID61
ID71
SHARP
ID11-13-40
ID11-13-44
Wafer
ID 54
ID61
2 μm details GLOBALFOUNDRIES Public
Defects in Ru-pad Area
13
Absorber on reflecting Ru type defects
100% Found by AIMS™ (2/2)
50% (1/2) by SHARP
No defect found on wafer
AIMS™
ID12
ID34
Wafer
ID16
ID31
SHARP
ID11-13-16
IDNA
.
Low absorbance defects w/ small
background to defect intensity ratio not found by SHARP
2 μm details GLOBALFOUNDRIES Public
Defects in Fill Area
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Absorber on reflecting Ru type defects
50% found by AIMS™ and SHARP (2/4)
Non-critical defect; defects don’t printing
on wafer
AIMS™
ID14
ID38
SHARP
ID11-13-02
ID11-13-21
Wafer
ID14
IDNA
Wafer image not available Location checked, no def.
2 μm details GLOBALFOUNDRIES Public
Defects Outside Pattern Area
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Absorber on absorber type
defects: dark on dark!
Low background-to-defect
intensity ratio
100% Found by AIMS™
(19/19), 63% (12/19) by
SHARP
Non critical defect; defects
don’t print on wafer
Low absorbance defects on dark absorber not found
by SHARP
AIMS™ has higher SNR for absorber-on-absorber defects
AIMS™
ID46
ID78
SHARP
ID11-13-34
ID47
AIMS™ only
ID74
2 μm details GLOBALFOUNDRIES Public
Conclusions
Actinic mask review provides capability to forecast defect printability on wafer
All defects printing as bridges or large area defects found by both tools
AIMS™ & SHARP’s images reproduce wafer prints with high fidelity
To detect and quantify small line necking or dark-on-dark defects, stage accuracy and S/N ratio are critical
100% defect printability detection capability shown by AIMS™
Future work: Programmed defect actinic review by AIMS™ & SHARP
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© 2014 GLOBALFOUNDRIES Inc. All rights reserved.
Acknowledgements
IMEC
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