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TRANSCRIPT
Jeroen Ottens
Metrology in the context of holistic Lithography
Public
Product System Engineer YieldStar, ASML
Lithography is at the heart of chip manufacturing25.April.2017
Public
Slide 2
Repeat 30 to 40 times to build 3 dimensional structure
Overlay and CD-Uniformity (CDU) are critical for device performance
20 November 2017
Public
Slide 3
Rule-of-thumb:
OV 30 % of CD
CDU 10 % of CD
OVCritical Dimension
(CD)Today’s devices: CD 16 nm
OV < 5 nm
CDU < 1.5 nm
Holistic Lithography Concept
Scanner aspects
Metrology aspects
- YieldStar
- Computational Metrology
- Pattern Fidelity Monitoring
Conclusions
25.Apirl.2017
Slide 4
Publicl
ASML Holistic Lithography approach seeks to
maximize patterning process performance and control
Full chip process window detection
Process Window Enhancement
Process Window Control
Lithography scanner with advanced capability (Imaging, overlay and focus)
Computational Lithography Metrology
1
3 2
25.April.2017
Public
Slide 5
1
Scanner aspects
25.April.2017Slide 6
Public
40 years projection lithographydriving performance improvements 3 orders of magnitude*
Slide 7
“Innocence”
UnderstandingModels and setup
Process controlMetrology feedback
Mark design and sampling
* Use overlay as example based on SPIE publications 1973 - 2015
Micralign
NXT:1950i
Holistic approachHigh order corrections
Integrated metrology
Computational litho
Design for control
Public25.April.2017
25.April. 2017
Slide 8
Public
ASML Scanners at the core of patterning control capability
ASML scanners measure 100% of the wafers ASML scanners knobs control every die
100% of the wafers
are measuredWafers processed
field by field
Metrology aspects
25.April. 2017
Slide 9
Public
ASML Holistic Lithography approach seeks to
maximize patterning process performance and control
Full chip process window detection
Process Window Enhancement
Process Window Control
Lithography scanner with advanced capability (Imaging, overlay and focus)
Computational Lithography Metrology
1
3 2
25.April. 2017
Public
Slide 10
Measurem
ent
Signal type Target size
( µm2 )
Primary application
Overlay
Pupil 40x160 Monitor wafer
Dark field image 10x10 On Product
Focus
Pupil 40x40 Monitor wafer
Dark field image 10x10 On Product
CD Pupil 40x40 – 5x5 Monitor & On Product
25.April. 2017
Slide 11
Publicl
YieldStar Optical Scatterometry SystemOverlay, Focus and CD measurement capability
YieldStar
Stand alone
Integrated
Applying scanner corrections needs holistic approach supporting* the setup & optimization of Overlay, Focus, Dose
Ramp Process development HVM
Optimal correction
models and sampling
Static process setup
Overlay and Imaging
On-Product Performance
3
Reduce Lot-lot and
Wafer-wafer variation
3Dynamic process
setup
wafe
r 2 w
afe
r
lot 2 lot
machine 2 machine
Reduce Impact of Variations
4Process control &
monitoring
Excursion control thru
scanner, metro &
process KPI monitoring
Maintain Performance
5
Matched
machine overlay
on all layouts
Scanner
Performance1
1.7nm
* Supported with LithoInsight (LIS) software and the off-tool Litho Computation Platform (LCP)
Optimal metrology
accuracy, precision
and throughput
Metrology setup
YieldStar and Smash
Metrology
mDBO
mDBF
SMASH XY
2
CD
Public
Slide 13
Improved Overlay performance with minimized samplingLogic example HOPC +CPE control
~ 2 month ~ 1 month
LiS control
Enabled
On
-pro
du
ct o
ve
rla
y [m
3s]]
LiS control
Saturated
POR control strategy :
POR Sampling 557 pt /wfr ; 1wfr/ck
Correction Model : HOPC3txty+iHOPC+Dynamic CPE
LiS control strategy :
SSO Sampling 200 pt/wfr ; 1wfr/ck (64% less than POR)
LiS Estimation Model : 5th order
Correction Model : Same as POR model
Product/layer : Logic/FEOL
Lot exposure via dedicate chuck on NXT:1970Ci
Monitoring trend via POR layout
Overlay measurement by multiple YS S-250
10 hours
Performance measured
on POR layout
Public
Slide 14
25.April. 2017
Slide 15
Public
Metrology Sampling Density RoadmapThe number of metrology points needed is higher than physically practical !
Computational metrologyPublic
Product wafer
Emu
late
d fi
nge
rpri
nt
BMMO
corr
ect
Ap
ply
measured wafer
Scanner with integrated YieldStar Stand-alone YieldStar
Scanner
interface
ADI
metrologyAEI
metrology
Focus
& CD
OVL
Comp. Metro
Focus ADI
OVL on device
Etcher
BMMO
residuals
YieldStarARM-CD/OVL
OVL ADI
ARM (LIS est.)(Waver level) corrections Comp. Metro
YS-IM YS-IDM
CD on device
SPIE 2017: W. Tel, Efficient Hybrid metrology for focus, CD, and overlay
Measured OVL
Computational Overlay for LELE case Evaluation after 2nd litho step
Computational Overlay =
etch+leveling+uDBO Delta OVL map
μDBO Level sensor etcher monitoring80 pts
200 pts
SPIE 2017: W. Tel, Efficient Hybrid metrology for focus, CD, and overlay
PublicSlide 17
<Date>
Slide 18
Publicl
Proof of principle CD
SPIE 2017: W. Tel, Efficient Hybrid metrology for focus, CD, and overlay
<Date>
Slide 19
Confidential
25.April. 2017
Slide 19
Publicl
28 February 2017
Public
Slide 20
Advanced in-production hotspot prediction and monitoring with micro-topography, 10145-33, SPIE Advanced Lithography, San Jose, CA, USA, Feb 28, 2017
HVM Defect patterning defect predictions on 100% of wafer
Simulated PW
Predicted Defect Map
Best focus mapDepth of focus
map
FEM per
HotSpot
Verification sampling plan
Hybrid process modulation map
+
On Wafer Defect Prediction
On Wafer Defect Observation
Validation
Note that (in this
experiment) validation
can only be done at the
same sampling scale as
verification plan
25.April. 2017
28 February 2017
Public
Slide 21
Advanced in-production hotspot prediction and monitoring with micro-topography, 10145-33, SPIE Advanced Lithography, San Jose, CA, USA, Feb 28, 2017
Patterning Fidelity Monitoring verifies the predicted defects on
wafer using E-beam CD metrology tools
HDFM focus map Defect prediction
7569 73
25 31 270
20
40
60
80
100
M3DR4 AI60L1R3_AI90L1R9 LMC19
Rat
e (
%)
Established good correlation between dense focus map and measured pattern defects
Defect observation
Capture rate: Percentage of successfully
(verified) predicted defect locations
25.April. 2017
Summary
- The large number of “knobs” on the scanner allows correction for
process variations both Intra- and Inter-field.
- The metrology required to feed control loops for high frequency spatial
and temporal process variations requires computational methods to
create per-wafer high density metrology information
- Combination of Scanner model, multiple metrology sources and
computational modeling allows for defect prediction and in turn scanner
model optimization.
25.April.2017
Slide 22
Publicl
Thank you !
25.April. 2017
Slide 23
Public
I would like to recognize the following ASML colleagues for their contributions:
Wim Tel, Stefan Hunsche, Marinus Jochemsen, Leon Verstappen,
Arie den Boef, Jan Mulkens, Martin Ebert
Overlay 3 orders of magnitude down¹
Overlay correctables 4 orders of magnitude up
The future: extending Holistic approachHigh order corrections
Process robust metrology, broad wavelength, polarization
and multiple orders using marker reconstruction,
Integrated metrology
Computational litho and metrology optimization
Dense on product sampling enabling litho control; lot-lot,
wafer-wafer, on product
Reference : Key note Metrology conference 2016 . M vd Brink
#U
se
r s
ele
cta
ble
lit
ho
co
rre
cti
on
s
Public
Slide 24
Improved Overlay performance for Logic HOPC + CPELogic example HOPC +CPE control : 23% average overlay improvement,64% less samples
~ 2 month ~ 1 month
LiS control
Enabled
On
-pro
du
ct o
ve
rla
y [m
3s]]
LiS control
Saturated
POR control strategy :
POR Sampling 557 pt /wfr ; 1wfr/ck
Correction Model : HOPC3txty+iHOPC+Dynamic CPE
LiS control strategy :
SSO Sampling 200 pt/wfr ; 1wfr/ck (64% less than POR)
LiS Estimation Model : 5th order
Correction Model : Same as POR model
Product/layer : Logic/FEOL
Lot exposure via dedicate chuck on NXT:1970Ci
Monitoring trend via POR layout
Overlay measurement by multiple YS S-250
10 hours
Performance measured
on POR layout
Public
Slide 25
<Date>
Slide 27
Confidential
Proof of principle for Focus
Level Sensor: measures wafer height map h(x,y)
20 November 2017
Public
Slide 28Requirements:
1. Accuracy: nm-range
2. Available time: few seconds
3. Resolution: 22 mm2
Concept: optical triangulation
grating (pitch P)grating
detector
Wafer stage
wafer
Light
source
sin2
P
h
detector
response
measured
height
Height variations are caused by:
1. Wafer thickness variations
2. Layer thickness variations
3. Deformation (warp) due to processing
Image
rotation
prisms
+90
-1 +1
(+1,-1)
(+1,-1)
detector
wafer
laser
-90
Wafer stage X
P
XAA 122 4cos
X1X0 X2
Solution: Interferometric alignment sensor (“SMASH”):measures the position of any target with 180 rotation symmetry
20 November 2017
Public
Slide 29
1je
A1-je
A
X1
X0
PX
4
111
P
X11 2
P
X11 2
1--1 is measured with a
self-referencing interferometer
<Date>
Slide 30
Confidential
Level Sensor and Alignment run in parallel with wafer exposure
20 November 2017
Public
Slide 31
Overlay [nm]55 WPH 125 WPH 185 WPH145 WPH
NXE:3300B
NXE:3350B
NXE:next
High NA
Slide 32
Public
EUV extension roadmap
NXE:3400B2017
2015
2013
introduction
products under study
7
3.5
3
<3
<2
SPIE 2017
More on high-NA in talk of Alberto Pirati: 10143-12