EUV patterning improvement
toward high-volume manufacturing
Tokyo Electron Kyushu Ltd. / SPE process dept.
Y. Kuwahara, K. Matsunaga, K. Nafus, S. Kawakami
imec
P. Foubert, A-M. Goethals
2015 International Workshop on EUV Lithography
P63
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 2
Introduction
• Extreme ultraviolet lithography (EUVL) technology is a
promising candidate of semiconductor process for 18nm half
pitch and beyond.
It still requires fine resolution, uniform, smooth patterns and
low defectivity, not only after lithography but also after the
etch process.
• Tokyo Electron Limited and imec are continuously collaborating
to develop manufacturing quality POR processes to EUV with
CLEAN TRACKTM LITHIUS ProTMZ-EUV.
We evaluated defectivity at post lithography and post etch
process.
New rinse material and application compatible with sub 18nm
patterning is performed to prevent line pattern collapse on
several resist materials, because rinse material compatibility
with resist is concerned.
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 3
39%
4% 22%
9%
1%
25%
underlayer/SI embeddedmicro bridge protrusionresidue collapse
EUVL 32nm L/S Defects after Litho
Embedded Defect reduction is the Key Challenge
Ta
rge
t D
efe
ct D
en
sity (
de
fects
/cm
2)
0.50
0.45
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Resist-A,
Mar. 2012
Resist-A,
July 2012
Resist-A,
Jan. 2013
Resist-A,
Jan. 2014
0.70
0.18
0.12 0.09
Target Defect
Bridge Embedded
Yuhei Kuwahara/TEL – Philippe
Foubert
/imec et. al, SPIE 2014
25% Reduction
Coating related defects are still majority of the defectivity
Defect Budget SPIE2014
1. Coating related 74%
(UL, EM, MB, Prt)
2. Collapse 25%
24%
45%
15%
1% 12%
1%
underlayer/SI embeddedmicro bridge protrusionresidue collapse
Mar. 2012
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 4
Baseline Defectivity Result ADI&AEI
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Post litho (ADI) Post Etch (AEI)
No
rma
lize
d D
efe
cti
vit
y
Protrusion
Microbridge
Embedded
1.0
3.95
ADI&AEI Common Defect
AEI Specific Defect
AEI Defect Images
Micro Bridge Embedded
After etch inspection is much more sensitive, post etch defect
reduction need to be addressed.
Protrusion
Micro Bridge
Protrusion Protrusion
SoC/SoG/EUV Resist-B
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 5
After Etch Defect Model Resist Film Defect
Under Layer Film Defect
Resist
SoG
SoC
Resist
SoG
SoC
Resist
SoG
SoC
Detectable at ADI
Un-detectable at ADI
Un-detectable at ADI
Coating related defect reduction is important to after etch defect
reduction
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 6
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Baseline FEF Baseline FEF
SiARC EUV-Resist
No
rmalized
Bla
nket
Defe
ct
Protrusion Dent Embedded
Coating Defect Reduction by New
Technologies at TEL in-house
Protrusion
Dent
Embedded
Defect Inspection : KLA2900 (KLA-Tencor)
ACI defects
81%
New Function can reduce blanket coating defect for several
materials
71%
Before verification of pattern defect , executed preliminary test
for coating defect reduction by new dispense system.
EUV Resist-C
New New
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 7
Evaluation of AEI Defect Reduction
New New New
Resist-B
SoG
SoC
SoC SoG Resist-B
Coating scheme
Etch
Defect Inspection
KLA2835
Defect Inspection
KLA2835
NXE3100
L/S HP32nm
Baseline Baseline Baseline
Root cause of AEI defects are investigated by using coating defect
reduction technologies.
ADI AEI
Experiment Flow
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
baseline New baseline New
post litho post etch
No
rma
lize
d D
efe
ct
De
ns
ity
Embedded Microbridge Particle Protrusion
AEI Defect Reduction Result
59% 1.0
0.41 0.60
Defectivity is drastically improved by New Function, AEI defectivity is
sensitive with coating defect.
Micro bridge and Embedded defect reduction is main contributor.
85%
3.95
Micro Bridge
Total 97%
Reduction
Total 84%
Reduction
AEI Defect Images
Embedded
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 9
Pattern Collapse Mitigation
θ
W
h
D
r
σ σ
θ
W
h
D
r
σ σ σ=6γcosθ/D×(h/W)2
σ;The maximum stress which works to pattern
γ;Surface tension of rinse θ;Contact angle
h;Height of pattern D;Space of pattern
W;Width of pattern h/W;Aspect ratio
N. Namatsu et. al., Appl.. Phys. Lett. 66(20), pp.2655-2657, (1995)
39%
4% 22%
9%
1%
25%
underlayer/SI embeddedmicro bridge protrusionresidue collapse
Defect Budget SPIE2014
Approach to tackle this challenge
− Surface tension reduction by introducing a New ‘FIRMTM Material’
Check the resist compatibility below 20nm pattern
18nm Line& Space Pattern Collapse
18nm Line& Space Pattern Melt
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 10
FIRMTM Rinse Material Evaluation
20nmHP of Resist-B
smallest
CD [nm]
⊿CD from DIW
[nm]
LWR
[nm]
DIW 17.6 - 7.1
ExtremeTM10 16.8 1.0 6.8
ExtremeTM A 15.2 -0.2 7.2
DIW Rinse ExtremeTM10 ExtremeTM A
Process
window
Available:20 Available:15 Available: 21
12
14
16
18
20
22
24
13 15 17 19 21 23 25
CD
[n
m]
Dose [mJ/cm^2]
DIW Ex-10 Ex-A
ExtremeTM A
DIW ExtremeTM 10
No collapses
Unavailable pattern
(collapse, no resolution, melt)
Dose
Focus
※ExtremeTM is a registered
trademark of AZ Electronic
Materials.
ExtremeTM A has
− best smallest CD without pattern collapse.
− Smaller CD change from DIW process than ExtremeTM 10
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 11
FIRMTM Rinse Material Resist
Compatibility below 20nm Pattern
Half pitch /
Resist
DIW ExtremeTM10 ExtremeTM A
HP 18nm /
Resist -D
HP 17nm /
Resist-E
No collapses
Unavailable pattern
(collapse, no resolution, melt)
smallest CD [nm]
⊿CD [nm]
LWR
[nm]
HP 18nm /
Resist-D
DIW 16.7 - 6.9
ExtremeTM10 16.0 1.7 6.4
ExtremeTM A 14.9 0.4 6.9
HP 17nm /
Resist-E
DIW 16.2 - 8.5
ExtremeTM10 17.6 1.2 8.0
ExtremeTM A 15.2 0.1 8.2
Available:27 Available:16 Available: 27
Available:9 Available:8 Available: 8
Dose
Focus
Dose
Focus
ExtremeTM A shows pattern
collapse mitigation for
− Below 20nm pattern
− Several resist materials
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 12
DIW Rinse ExtremeTM10 ExtremeTMA
18nm HP Process Window and
X-section SEM with Resist-E
CD±5% DIW Rinse ExtremeTM10 ExtremeTMA
Max EL 4.3% 8.9% 6.9%
Max DoF 80nm 80nm 280nm
Dose to Size 36.3(mJ/cm2) 38.3(mJ/cm2) 36.2(mJ/cm2)
0
1
2
3
4
5
6
7
8
9
10
0.00 0.10 0.20 0.30
Ex
po
su
re L
ati
tud
e(%
)
Depth of Focus(um)
DIW Rinse Extreme-10 Extreme-A
18nm HP Process Window
18nm HP X-section
ExtremeTM A achieved
− greater process window than Extreme10
− no significant impact to pattern profile and thickness
Height:25-31nm Height:24-29nm Height:21-28nm
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 13
60%
100%
20% 80% 100% 100% 60%
60%
60% 80% 100% 0% 100% 100% 40%
0%
80% 100% 0% 100% 100%
0%
100% 100% 0% 80% 100%
100%
100% 80% 100% 100% 100% 100% 100%
100%
80% 100% 100% 100% 100% 100% 100%
100%
60% 100% 80% 100% 100% 100% 100% 100% 80% 100% 100% 100% 100% 100% 100% 100% 100% 80% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 80% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 0%
100%
100% 100% 100% 100% 100% 100% 100%
80%
100% 100% 100% 100% 100%
100%
80%
100% 0%
100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100% 100% 100%
100%
100% 100% 100% 100% 100%
100%
100%
Collapse
Total 532 images/wafer
FIRM ExtremeTM10 FIRM ExtremeTMA
Standing Ratio
Ave. CD 16.4nm
3sigma:1.6nm Ave. CD 16.6nm
3sigma:0.7nm
Pattern collapse is completely mitigated by FIRM ExtremeTMA on 16nm
line pattern.
100% 88%
L16nm P36nm with ExtremeTMA and Resist-E
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 14
Conclusion
Defect reduction is key for the EUV manufacturing, especially
post etch defectivity.
Post Etch defectivity is reduced 85% by using New Function.
Pattern collapse is one of the critical issue of the EUV
lithography.
FIRM ExtremeTMA has demonstrated greater pattern collapse
mitigation and process window enhancement on even below
20nm HP pattern.
In addition, FIRM ExtremeTMA has great compatibility with
several imec POR materials.
P63, 2015 International Workshop on EUV Lithography
Y. Kuwahara / Tokyo Electron Kyushu Ltd. / SPE Process Technology Dept. / Rev. 1/ 15
• The authors would like to extend their appreciation to
– Tokyo Electron Kyushu Ltd. SPE Process Technology department
– Tokyo Electron Europe Ltd. service team
– Tokyo Electron Miyagi Ltd. Product engineering
Acknowledgement