Post on 06-Jul-2020
NXE:3300 INSERTION FOR N7 : STATUS AND CHALLENGESVicky Philipsen, Iacopo Mochi, Lieve Van Look, Gian Lorusso, Kim Vu Luong, Eric Hendrickx (imec)
Friso Wittebrood, Guido Schiffelers, Eelco Van Setten, Timon Fliervoet, Mircea Dusa (ASML)
2015 International Symposium on Extreme Ultraviolet Lithography - Oct. 5. - Maastricht
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
INTRODUCTION
EUV insertion in N10 @imec
Critical Metal pitch = 48nm; Critical contacted poly pitch = 64nm
2D single patterning with EUV demonstrated
EUV insertion in N7 @imec
Critical Metal pitch = 28-36nm; Critical contacted poly pitch = 42nm
Different patterning options :
2
2D patterning with EUV 1D patterning with EUV 1D patterning with 193i MP
+ block with EUV
Scope of this work:
Generate experimental NXE:3300 data of N7 Metal compatible structures
to verify printability limits in support of N7 patterning choices
STATUS N7 PRINTABILITY
• resolution pitch for trenches
• tip-to-tip
• 2D constructs
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
STATUS N7 METAL PRINTABILITY
4
Based on
illumination
Resist readiness of CAR
3 resists evaluated
for
Resolution pitch for trenches
Tip-to-tip
2D constructs
using
NXE:3300 exposures at ASML-DEMO lab in Veldhoven
Annular
100%Quasar 45°
100%Quasar 24°
50%1D-SMO
100%
Tachyon SMO NXE FlexPupil
for 30nm pitch vertical
trenches and 24nm gaps
illumination efficiency
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
RESOLUTION PITCH
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SIMULATION of VERTICAL 1:1 TRENCHES
CPPMxP
• pitch 42nm (CPP) shows NILS well above 2 for Annular and Quasar illumination
• pitches around 32nm (MxP) require pupil optimization towards more Dipole-like setting
to get NILS > 2
100% ill. eff.
100% ill. eff.
50% ill. eff.
Tachyon
SMO NXE
FlexPupil 100% ill. eff.
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
RESOLUTION PITCH
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WAFER VERIFICATION of VERTICAL 1:1 TRENCHES
• Experimental evaluation confirms decrease in resolution pitch by pupil optimization
• Pitches ≤ 32nm show line pinching further process optimization required
Pitch 36nm Pitch 34nm Pitch 32nm Pitch 30nm Legend:
Decent PW
Good imaging
at BE, BF only
No PW
Resist A
Resist A
Resist A
Resist B
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
Resist A
Resist B
Resist C
Quasar 24deg opening angle shows larger
EL than Quasar 45deg opening angle
Evaluated resists perform equally ~ 40mJ/cm²
EXPOSURE LATITUDE
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WAFER VERIFICATION of VERTICAL 1:1 TRENCHES
• Contacted Poly Pitch 42nm for N7 can be easily achieved with Quasar illumination
• Metal x Pitch 34nm shows increasing EL with pupil optimization
Contacted Poly Pitch 42nm; Target CD 24nm
Large Annular has lower EL than Quasar;
in accordance with NILS
Evaluated resists perform equally ~ 40mJ/cm²
Metal x Pitch 34nm; Target CD 17nm
Resist A
Resist B
Resist C
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TIP-TO-TIP PRINTABILITY
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in 2D patterns and 1D patterns
To enhance printability of generic tip-to-tip a hammer head is applied in the mask design:
printability of generic tip-to-tip evaluated :
Mask: Aerial
contour:
Mask: Aerial
contour:
Pitch
Gap
Pitch 36 and 40nm ; Gap 10, 14, 18, 22, 26nm
Hammer head extension 2nm; HH length 20nm Hammer head not optimized
2nm
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TIP-TO-TIP PRINTABILITY
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ILLUMINATION IMPACT
• Pupil optimization for Metal x Pitch allows smaller printed tip-to-tip
• Printed gap CD is in range for the N7 requirement
illumination source has large impact in minimal printed gap
Quasar shape needed to print gaps around 23nm (i.e., N7 target gap)
illumination source has impact on dose sensitivity of printed gap
36nm 1:1 trench pitch printed through Gap width in resist B
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
PRINTABILITY OF 2D CONSTRUCTS
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Note:
OPC on mask was applied, not optimized for the
applied illuminations
Tip-to-tip 22nm
Pitch 38nm
Pitch 34nm
Contrast simulation:
Contrast 0.67 ~ NILS 2NILS ≥ 2 for good in-resist
performance
Target layer of 2D construct:
• Contrast is sufficient for Quasar and 2D-SMO illumination on three selected spots
Tachyon SMO
NXE FlexPupil
100% ill. eff.
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
PRINTABILITY OF 2D CONSTRUCTS
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ILLUMINATION IMPACT
• 2D printability can be improved by choosing the appropriate resist process
• Pupil optimization can further help 2D printability
Resi
st A
Resi
st B
47.7mJ/cm² 45.9mJ/cm² 46.8mJ/cm²
43.2mJ/cm² 41.4mJ/cm²
CHALLENGES IN EUV PRINTABILITY
• Best Focus shifts through pitch
• 2bar asymmetry through focus
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
CHALLENGES IN EUV PRINTABILITY
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@ wafer level:
• H/V bias
• Best Focus shifts through pitch
• Pattern shifts through focus
• 2bar asymmetry through focus
Multilayer mirror
Patterned absorber
@ mask level:
• Mask topography
• Oblique incidence of EUV light
• Multilayer reflectivity
• Off-axis illumination
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
BEST FOCUS THROUGH PITCH
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• experimental manifestation of Mask 3D effect predicted by rigorous simulations
Vertical trenches through pitch (34nm to 88nm)
35nm
42nmExperimentally determined Best Focus through pitch are
illumination dependent
strongest at the smaller pitches (≤ 48nm)
predicted by rigorous mask 3D simulation
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
PROCESS WINDOWS THROUGH PITCH
15
• Mask 3D effect influences partly the overlapping process window
Overlapping process window is experimentally limited by smallest pitch
Depth-of-Focus of overlapping process window ~ 100nm
Total focus control of NXE:3300 ~ 110 70nm
Vertical trenches through pitch (34nm to 88nm)
overlapping DoF > total focus control
safe imaging regime
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TWO BAR PRINTABILITY
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Pitch 36nm Horizontal in long pitch 1500nm
Best Focus difference between
LeftLower and RightTop trench
Vertical 2-bar
LeftL
ow
er
trench
Righ
tTop
trench
Cente
r Lin
e
Pitch
long pitch
BEST FOCUS DIFFERENCE
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TWO BAR PRINTABILITY
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BEST FOCUS DIFFERENCE
• experimental evidence of Best Focus difference partly due to Mask 3D and tool setting
Best Focus difference is pitch dependent
Best Focus difference is slit position dependent
Larger Best Focus differences for Dipole Y illumination
~center slit
Horizontal
~right edge slit
Horizontal
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TWO BAR PRINTABILITY
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CD DIFFERENCE THROUGH FOCUSPitch 36nm Horizontal in long pitch 1500nm
CD difference between
LeftLower and
RightTop trench
Horizontal 2-bar
LeftLower trench
RightTop trench
Center Line
Pit
ch
long
pitch
CD asymmetry through focus
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
TWO BAR PRINTABILITY
19
CD DIFFERENCE THROUGH FOCUS
• experimental manifestation of Mask 3D effect in 2-bar asymmetry through focus
CD asymmetry apparent in horizontal orientation
Dipole Y illumination induces stronger CD asymmetry than Quasar illumination
~center slit
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
CONCLUSION
Experimental EUV patterning exploration for N7 using 2D and 1D
on NXE:3300
with current resist processes
with moderate pupil optimization
demonstrates
trench pitch down to 34nm
printed gap CD down to 20nm
shows potential towards 32nm trench pitch
by pupil optimization
by resist process improvement
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STATUS N7 PRINTABILITY
2D patterning with EUV 1D patterning with EUV
Tachyon SMO NXE FlexPupil
with 100% ill. eff.
Resist B
Vertical pitch = 32nm; 1:1 L:S
Printed trench CD = 15.9nm
Nominal gap CD = 8nm
Printed gap CD = 26.5nm
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
CONCLUSION
show best focus shifts through pitch
show 2-bar asymmetry through focus
induced by mask 3D effect
need to be considered in design rules
or need mitigation strategies
illumination source optimization
OPC including assist features
mask absorber tuning
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CHALLENGES IN EUV PRINTABILITY
Related work at this Symposium:
o Process variation in N7
o Eelco van Setten, this Session
o Mitigation of M3D effect
o Friso Wittebrood, this Session
o Kim Vu Luong, Session 9 on Wed.
o Resist process improvement
o Mieke Goethals, P-IM-06
towards EUV extendibility beyond N7
2015 International Symposium on Extreme Ultraviolet Lithography, Maastricht
ACKNOWLEDGEMENTS
Maarten van Dorst, Peter Rademakers and the ASML DEMO team in Veldhoven
David Rio (ASML – Brion)
Panoramic
Synopsys
Osamu Inoue-san (Hitachi)
Berkcan Gokce, Mieke Goethals, Werner Gillijns, Jeroen Van de Kerkhove (imec)
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