enhancing resolution of the albany alpha-demo tool (adt) with...
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© 2012 IBM Corporation
Enhancing Resolution of the Albany Alpha-Demo Tool (ADT) with Pupil Filtering
EUVL Symposium 2012
Gregory McIntyrea, Leon Teeuwenb, Obert Woodc, Erik Sohmend, Daniel Corlissa, Theo van den Akkerb, Sander Boutenb, Eelco van Settenb, Oleg Voznyib, Sang-In Hanb, Hermann Biegd, Martin Burkhardta, Karen Petrilloa, Alexander Friza a IBM Corporation, Albany Nanotech, Albany, NY 12203
b ASML, Albany Nanotech, Albany, NY 12203
c GLOBALFOUNDRIES, Albany Nanotech, Albany, NY 12203
d Carl Zeiss SMT GmbH, Oberkochen, Germany
© 2012 IBM Corporation 2 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Motivation & Outline
Outline:
Theory
Pupil filter concept
Optimum pupil filter designs
Standard imaging filters
Frequency doubling filters
Experimental results
22nm HP line-space
24nm HP contacts
Areas of development
Summary
Motivation: Enable next-node process development at select features
beyond the resolution limit of current tooling
© 2012 IBM Corporation 3 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
3 beam imaging
Traditional imaging (ADT > 27nm HP)
nmNA
Lw 275.0(min)
Source is fixed tophat with =0.5
All on-axis illumination rays contribute to imaging
source
wafer Mask
HP = 27nm
=0.5
lens
© 2012 IBM Corporation 4 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Traditional imaging: Reduce HP below 27nm Central bundle of rays do not image
They provide DC background & reduce image contrast
Mask
HP < 27nm
=0.5
© 2012 IBM Corporation 5 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
2 beam imaging
nmNA
Lw 1833.0(min)
Traditional imaging: Reduce HP below 27nm
Some rays provide 2 beam imaging
Central bundle of rays do not image
They provide DC background & reduce image contrast
Mask
HP < 27nm
=0.5
© 2012 IBM Corporation 6 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
2 beam imaging
nmNA
Lw 1833.0(min)
Concept: standard filter
Eliminate rays that do not contribute to imaging
=0.5
Pupil Filter
© 2012 IBM Corporation 7 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Contr
ast
Half-pitch (nm) 16 19 22 25 28
Coherent rays
Concept: standard filter
Simple rectangular
example
Vary filter size 22nm HP with filter
provides comparable
contrast to 28nm HP without
filter
Exact benefit will depend
on capabilities of resist
Optimum filter size exists
for each pitch
Image Contrast
0
1
0.5 No Filter
© 2012 IBM Corporation 8 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Mask
Optimized line-space filter (standard imaging) Ensure 1st order
captured in pupil
0
2
4
6
8
10
20 22 24 26 28 30
No Filter
Filter
Dose +/- 5%
Mask Error +/- 0.5nm
Focus Error +/- 40nm
Good resolution and good CD
Uniformity to 22nm HP
Filter design through pitch
22 23 24 25 26 27 28 Half-pitch (nm)
Half-pitch (nm)
Sim
ula
ted
CD
U (
nm
)
22 23 24 25 26 27 28
Half-pitch (nm)
Acceptable imaging of isolated features (i.e.
SEM marks, Reticle align marks, etc.)
0
0.5
1
1.5
2
2.5
20 22 24 26 28 30
Dose
Multiplier
Half-pitch (nm)
Increase in dose required ~2.2x for 22nm HP
© 2012 IBM Corporation 9 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
22x22HP Contact, capture minimum 1 order in each X and Y orientation
Optimized contact filter (standard imaging)
Image Cutline
Inte
nsity
Position
Aerial Image
0
5
10
15
20
25
30
22HP no filter 22HP filter
CDU_dose
CDU_meef
CDU_defocus
63% improvement in CDU
Mask S
imu
late
d C
DU
(n
m)
No Filter Filter
No Filter
Filter
Coherent rays
Filter design
No Filter Filter
© 2012 IBM Corporation 10 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Optimized contact filter (standard imaging)
X-orientation Half-pitch (nm)
22 23 24 25 26 27 21
Y-o
rienta
tion H
alf-p
itch (
nm
)
22
23
24
25
26
27
21
Optimized filters for various contact sizes
© 2012 IBM Corporation 11 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Square Contact Filters
Optimized contact filter (standard imaging)
0
2
4
6
8
10
12
20 22 24 26 28 30
Half-pitch (nm)
0
5
10
15
20
25
30
20 22 24 26 28
No Filter
Filter
Sim
ula
ted
CD
U (
nm
)
Do
se
Mu
ltip
lier
Half-pitch (nm)
Good resolution and good CDU
to ~22nm HP
Required dose increase likely limits
minimum HP to ~24nm
© 2012 IBM Corporation 12 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Concept: frequency doubling filter Increase mask pitch, block all of 0th order
Wafer pitch is frequency doubled (similar to ALT-PSM imaging)
=0.5
Freq. Doubled
2 beam imaging nm
NALw 5.1325.0(min)
Mask
HP = 2x wafer HP
© 2012 IBM Corporation 13 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
15 16 17 18 19 20 14 21 22 23 24 Wafer half-pitch (nm)
Filter designs through pitch
Frequency doubling filter (1D line-space)
0
2
4
6
8
10
12
12 14 16 18 20 22 24 26
No Filter
Filter
Dose +/- 5%
Mask Error +/- 0.5nm
Focus Error +/- 40nm
Very small resolution and great CDU to ~15nm HP
Sim
ula
ted
CD
U (
nm
)
CDU
15nm HP
No Filter Filter
© 2012 IBM Corporation 14 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
0
5
10
15
20
25
12 16 20 24
Do
se
Mu
ltip
lier
Half-pitch (nm)
15 16 17 18 19 20 14 21 22 23 24 Wafer half-pitch (nm)
15 16 17 18 19 20 14 21 22 23 24 Wafer half-pitch (nm)
Filter designs through pitch
Frequency doubling filter (1D line-space)
Poor printing of isolated features (requires alternate strategies for reticle
alignment, SEM navigation, etc.)
Reasonable dose multiplier
down to ~16nm HP
© 2012 IBM Corporation 15 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Frequency doubling filter (contacts)
Ideal design
21
30
Filter
Mask
Image
30nm HP square array on mask produces 21nm HP staggered array
22.6 24.0 25.5 26.9 28.3 29.7 21.2 31.1
Wafer half-pitch (nm)
23 26 29 32 20
Wafer staggered half-pitch (nm)
Image Contrast
Contr
ast
Through pitch with modified filter
Modified for
reasonable dose
21
30
© 2012 IBM Corporation 16 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Motivation & Outline
Outline:
Theory
Pupil filter concept
Optimum pupil filter designs
Standard imaging filters
Frequency doubling filters
Experimental results
22nm HP line-space
24nm HP contacts
Areas of development
Summary
Motivation: Enable next-node process development at select features
beyond the resolution limit of current tooling
© 2012 IBM Corporation 17 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Filter
Design
Half-pitch
Feature
Filter #
22LS
line-space
standard
line-space
standard
22LS 27x22CH 19LS 21CH
contact
standard
line-space
freq double
line-space
freq double
Type filter
1 3
24CH
contact
standard
2 4 5 6
6 Filter designs being tested experimentally
installed installed
In final processing, expected Oct ‘12
Status
© 2012 IBM Corporation 18 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Development and installation of
hardware solution (NA Handler)
complete
NA handler
Hardware enablement on ADT
Modified hardware originally
designed to allow multiple NA
settings
ADT-specific hardware solution
© 2012 IBM Corporation 19 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Pupil filter validation (22nm HP Line-space) Concept validated, showing ~20% improvement in ADT resolution
Resist process evaluation and development has begun
No Filter Resist D Resist B Resist C Resist A
With Filter
>10% Exposure latitude for 10% CD
0%
2%
4%
6%
8%
10%
12%
14%
16%
Slit 1 Slit 2 Slit 3 Slit 4 Slit 5 Slit 6
Resist A
Resist B
Resist C
Resist D
Exposure latitude for 10% CD
© 2012 IBM Corporation 20 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Resist process optimization ongoing
See also: Jun Hatakeyama, et al., “Reduction of LWR by Advanced
Polymer bound PAG based EUV resist” EUVL Symposium, 2012
Provided by Takashi Saito (TEL)
© 2012 IBM Corporation 21 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Mask LER transfer study with pupil filters
Photomask LER Transfer
Function with Pupil Filter (22HP)
SPIE Photomask 2012
Mask LWR
Programmed LER Mask
Resist LWR
© 2012 IBM Corporation 22 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Filter design Simulated image
in resist
No filter
Filter
24nm HP contacts
24nm HP contact filter (15% improvement in ADT resolution)
Fabricated filter
Successful printing in resist; beginning process development
No Filter With Filter
© 2012 IBM Corporation 23 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Pupil filtering: Areas of development
Slit uniformity: Presence of pupil
filter is impacting across slit intensity
uniformity optimization with unicom
blades.
Pupil filter No filter
Inte
nsity
Slit position Slit position
Optimized reticle alignment procedure to
improve reticle align repro and enable alignment
of frequency doubling filters
No filter
Pupil filter
Fla
re (
%)
Box size (um^2)
Out of Band stray light suspected to
be large with current filter.
Measurements show stray light in ~1um
range ~2x larger with filter installed.
Developed coating to minimize OoB reflections
Some filters redesigned to minimize stray light current redesign
22HP LS
© 2012 IBM Corporation 24 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Theory: Filters could enable ~12nm HP w/ NXE3300B
dipole90X
source
13 15 17 19 11
Half-pitch (nm)
Sim
ula
ted C
DU
(nm
)
13 14 15 16 12
Half-pitch (nm)
Filter designs
17
Concept could apply to any projection printing system with fixed illumination
Note: Hardware for filter exchange does not exist on NXE
© 2012 IBM Corporation 25 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Summary: Resolution enhancement with pupil filtering Demonstrated 20% improvement in resolution limit of ADT
Purpose is to enable process development at feature sizes beyond the
resolution limit of current tooling
Filters designed for optimum imaging performance of a specific feature
Hardware developed and installed on ADT for filter exchange
Experimental verification with 22HP line-space and 24HP contact filters
Concept extendable to any projection printing system with fixed illumination
Additional four filters in final fabrication 22HP LS 27x22 Via 38HP LS 42HP Via
© 2012 IBM Corporation 26 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Acknowledgements The authors would like to thank the following individuals and companies for
their assistance:
Brian Lee, Jerry Woods, Brian Niekrewicz, James Waddell (ASML)
Takashi Saito & Lior Huli (TEL)
Luke Orsini (IBM)
Matt Colburn, Cecilia Smolinski & David Mederios for management
support (IBM)
This work was performed by the Research Alliance Teams at various IBM
Research and Development Facilities
© 2012 IBM Corporation 27 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Backup
© 2012 IBM Corporation 28 G. McIntyre, 2012 EUVL Symposium, “Enhancing Resolution of the Albany ADT with Pupil Filtering”
Dose requirements
High dose values required
depending on amount of light
blocked by filter
ADT maximum exposure
time per die is 830 seconds,
which can limit scan length
Current collector near end
of life; new collector expected
soon and should increase
power by >100%
Scan length [mm] as function of ALP [uW] per dose [mJ/cm^2]
0
5
10
15
20
25
30
35
40
0 5 10 15
ALP [uW]
Scan
len
gth
[m
m]
- o
vers
can
5mJ/cm^2
10mJ/cm^2
15mJ/cm^2
20mJ/cm^2
25mJ/cm^2
30mJ/cm^2
40mJ/cm^2
50mJ/cm^2
60mJ/cm^2
70mJ/cm^2
80mJ/cm^2
90mJ/cm^2
100mJ/cm^2
max die size
includingoverscan
Min scan
length
48CA 44LS