Defect inspection and characterization
on actinic blank inspection tool
Hidehiro Watanabe, Ichiro Mori EUVL Infrastructure Development Center(EIDEC):
Lasertec Corporation: Hiroki Miyai, Tomohiro Suzuki, Kiwamu Takehisa, Haruhiko Kusunose
EUVL symposium 2014
1. ABI tool development status
2. Defect printability
3. Defect characterization
4. Summary
Contents
1
EUVL symposium 2014
ABI tool development status
2
0%
20%
40%
60%
80%
100%
1 70
1.2 56
0.95 55
1 43
1 41
1 36
0.8 32
Height Width
Capture Rate, Programmed defects
ABI HVM Tool is ready to play an important role in phase defect control
Tsuneo Terasawa et al., Development of actinic full-field EUV
mask blank inspection tool at MIRAI-Selete, Proc. of SPIE
vol. 7271 (2009)
Dark field inspection
Actinic inspection
K. Goldberg et al., “Defect detection and inspection unmasked”,
IWEUVL, 2010
nm
nm
EUVL symposium 2014
EIDEC/Lasertec BI Program Schedule
3
2010 2011 2012 2013 2014 2015
Parts Fabrication
Development Improvement
EIDEC BI program1) started
Additional 1200x Review function
fabrication evaluation
Tool Design
1) BI Program: Blank Inspection program
Defect classification
Inspection started
Prototype tool for HVM 16nm hp Prototype tool upgrade
- Printability study
- Inspection capability
evaluation
- Location accuracy
evaluation
Achieved Basic performance
EUVL symposium 2014
ABI tool – inspection performance
4
0
50
100
150
200
250
Cumulative inspection area In
spe
ction
are
a / 1
04m
m2
- The ABI tool inspected more than 200 x104mm2 in one year.
- Signal intensity has been stable during this period.
- The ABI tool meets the 16nm-sensitivity requirement and is currently being
used for actual EUV mask blanks inspection.
The ABI tool has demonstrated its actinic inspection performance
through a year of operation.
EUVL symposium 2014
ABI tool - review function
5
0
20000
40000
60000
80000
100000 N
um
be
r o
f R
evie
ws
Cumulative number of reviews
- Actinic review is available for all defects detected by the ABI tool.
- The ABI tool performed more than 80,000 reviews in one year.
Actinic review function is crucial for understanding defect characteristics
1. ABI tool development status
2. Defect printability
3. Defect characterization
4. Summary
Contents
6
EUVL symposium 2014
Previous studies on printability of phase defect
7
Simulation study for Wafer impact as a function of ABI intensity
Noriaki Takagi et al., EIDEC symposium 2013
Relation between Printability simulation and experiment
Tsuneo Terasawa et al., EIDEC symposium 2013
Simulation on bridge defect
on wafer matched the
experiment result.
Simulation shows ABI signal
intensity proportionally co-
related to defect intensity on
wafer.
EUVL symposium 2014
Printing impact from ABI signal intensity
8
ABI signal intensity represents wafer printing impact
Width (nm)
ABI detection
threshold
10% CD error
for 16nm hp He
igh
t (n
m)
High
Low
Experimental ABI signal intensity
as a function of phase defect size
0 20 40 60 80
0
2
4
3
1
1. ABI tool development status
2. Defect printability
3. Defect characterization
4. Summary
Contents
9
EUVL symposium 2014
Defect characterization – ABI flow
10
Defect
Inspection
Low Magnification
Review
High Magnification
Review
-False elimination
-Phase / Amplitude
defect classification
1um 1um
-Pit/Bump classification
-Measurement of defect
location and size
-Defect map with DSI
(defect signal intensity)
Review of
each defect high
resolution
EUVL symposium 2014
Defect type EUV review DUV review
Phase Defect
(H2.4nm, W200nm)
Amplitude Defect
(H50nm, W76nm)
Phase / Amplitude defect classification
H22nm x W50nm carbon deposits
observable in DUV review
DUV review function
DUV
λ=193nm
defect
Schwarzschild
optics
11
With EUV and DUV reviews, Phase/Amplitude can be distinguished.
EUVL symposium 2014
Pit and Bump - Through focus images
12
3 um
PIT (-2.4x204nm)
BUMP (0.9x232nm)
-2.0um -1.0um 0.0um 1.0um 2.0um
Low magnification images
PIT (-1.7x63nm)
BUMP (0.9x72nm)
High magnification images 20 um
-2.0um -1.0um 0.0um 1.0um 2.0um
The position where the image focuses differs,
depending on whether the defect is pit or bump.
EUVL symposium 2014
No
rmal
ize
d in
ten
sity
PIT PIT1 (H1.7,W86)
PIT2 (H2.1,W98)
PIT3 (H2.4,W204)
-2.12 -1.62 -1.12 -0.62 -0.12 0.38 0.88 1.38 1.88 2.38 2.88
No
rmal
ize
d in
ten
sity
BUMP BUMP1 (H1.0,W97)
BUMP2 (H0.9,W116)
BUMP3 (H0.9,W232)
true 94%
6%
Pit / Bump classification function Through focus image analysis for pit/bump classification
judged form >100 samples of
programmed defect and native defect
Pit / Bump
classification result
13
miss judge pit
bump
With through focus image analysis, Pit/Bump classification is possible.
Threshold
-2 -1 0 1 2 Defocus /nm
Focus dependent intensity profiles for programmed phase defects
Details of focus dependency, see reference poster session “The influence of phase defect
characteristics on scattered light images in actinic dark field inspection” Noriaki Takagi, EIDEC
EUVL symposium 2014
Defect width
by AFM
72nm 101nm 108nm 120nm 154nm
Defect images
by high Mag.
review
Defect Diameter
from ABI images
55nm 76nm 95nm 112nm 120nm
Defect size measurement
14
Programmed phase defect images from high magnification optics
0
50
100
150
200
0 50 100 150 200
Defe
ct
siz
e f
rom
AB
I /n
m
Defect size from AFM /nm
Comparison of measurement results from ABI review and AFM
With ABI high magnification review images,
defect size measurement is possible.
1. ABI tool development status
2. Defect printability
3. Defect characterization
4. Summary
Contents
15
EUVL symposium 2014
Summary
16
1. The ABI HVM prototype performs EUV blank inspection and
review to assist the efforts to develop better EUV blanks.
2. ABI review images facilitate the following defect characterization,
which contributes to EUV blank defect management.
- Phase/Amplitude classification
- Pit/Bump classification
- Defect size measurement
EUVL symposium 2014
Acknowledgements
17
This work was supported by New Energy and Industrial
Technology Development Organization (NEDO) and Japan
Ministry of Economy, Trade and Industry (METI).
Thank you very much
for your attention.
This material contains confidential information.
Neither copy nor disclose to any third party is authorized
without prior written consent of Lasertec.
CONFIDENTIAL 18