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P BP BTT������������������������������
•• NanometrologyNanometrology requirementsrequirements
•• OverviewOverview of of instrumentationinstrumentation at PTBat PTB-- OpticalOptical maskmask comparatorcomparator-- ElectronElectron --opticaloptical metrologymetrology systemsystem-- New 1D New 1D vacuumvacuum nmnm --comparatorcomparator-- Angle Angle comparatorcomparator
•• International International comparisoncomparison Nano3Nano3
•• Future Future needsneeds
H. Bosse, PTB, Department 5.2 H. Bosse, PTB, Department 5.2 forfor lengthlength and angle and angle graduationsgraduations
NIST, NIST, GaithersburgGaithersburg , , JanuaryJanuary 2727--29, 200429, 2004
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DrivingDriving Technologies:Technologies:
-- SemiconductorSemiconductor productionproduction ((OverlayOverlay, , featurefeature placementplacement, CD, ...), CD, ...)
-- CD/DVD disc CD/DVD disc masteringmastering processprocess (linear (linear positionposition controlcontrol))
-- ProductionProduction of material of material measuresmeasures of of lengthlength and and lengthlength measuringmeasuring systemssystems
-- UltraprecisionUltraprecision machiningmachining
-- NanotechnologyNanotechnology, , nanostandardsnanostandards
-- ......
RequirementsRequirements::
-- ProvideProvide lengthlength and and xyxy--coordinatecoordinate valuesvalues traceabletraceable to SI to SI unitunit of of lengthlength
-- DetermineDetermine deviationsdeviations fromfrom 1D1D--linearity linearity oror 2D nominal 2D nominal patternpattern positionspositions
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PrerequisitesPrerequisites::
-- DisplacmentDisplacment measurementsmeasurements directlydirectly traceabletraceable to to thethe SI SI metermeter definitiondefinition
-- Position Position controlcontrol systemssystems forfor compansationcompansation of residual of residual guidingguiding deviationsdeviations
-- ApplicationApplication of of errorerror separationseparation methodsmethods to to determinedetermine residual residual deviationsdeviations
-- High High precisionprecision material material parameterparameter characterizationcharacterization: :
compressibilitycompressibility, thermal , thermal expansionexpansion
-- DevelopmentDevelopment of of modelmodel to to describedescribe probeprobe--samplesample interactioninteraction
-- ClearClear definitiondefinition of of measurandmeasurand
-- UncertaintyUncertainty budgetbudget accordingaccording to GUMto GUM
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-- OpticalOptical maskmask comparatorcomparator
-- ElectronElectron --opticaloptical metrologymetrology systemsystem
-- 1D 1D vacuumvacuum Nanometer Nanometer comparatorcomparator
-- Angle Angle comparatorcomparator
P BP BTT!�������!������������������������� ������������������ ��������
Current LMS 2020 performance for 2D coordinate metrology:- Repeatability in one orientation: 4 nm (3s)- Agreement of grid coordinates with mask measured in
different orientations: < 10 nm
PrinciplePrinciple TechnicalTechnical realizationrealization
Pattern placementcalibrations offered
to mask industrysince 1990
P BP BTT$���%&%&��$���%&%&���������'������������'����� ����������#���������#����� ��������������������
Results for Cr/quartz-photomask:
� 7´´ (178 mm) mask size
� (15 x 15) grid, 5 mm pitch
� 16 repeat measurements
� Differences from mean coordinates
� Statistics of observed differences:
x / nm y / nmmaximum 4,1 6,1minimum -4,7 -4,7mean 0,0 0,0std. dev. (3 s) 3,6 3,6
P BP BTT���� ������������������ ��������������������������������������������������������
CoordinateCoordinate system system withwith „„ errorserrors ““
0 °0 ° 90 °90 °
180 °180 ° 270 °270 °
4 4 orientationorientation methodmethod ::eliminationelimination of of instrumentinstrument deviationsdeviations
byby variationvariation of of phasephase of of signalssignals
ResultResult
butbut: : completecomplete errorerrorseparationseparation also also
needsneeds translationtranslation !!
P BP BTT$���%&%&��($���%&%&��())�������������������������������������������� ��������������������
Results for Cr/quartz-photomask:
� 7´´ (178 mm) mask size
� (15 x 15) grid, 5 mm pitch
� 4 orientations
� Differences from mean coordinates
� Statistics of observed differences:
x / nm y / nmmaximum 6,3 6,7minimum -6,2 -6,5mean 0,0 0,0std. dev. (3 s) 5,3 5,4
P BP BTT�*������*���������������������))*������*������ ������������������ ����������
PropertiesProperties ::
-- VacuumVacuum interferometryinterferometry forfordisplacementdisplacement measurementmeasurement
-- 300 mm 300 mm rangerange of xof x --y y stagestage
-- High High resolutionresolution lowlow voltagevoltageee--beambeam probe probe (5(5--10 nm)10 nm)
P BP BTT�*�����*���������������������� #����+�#����+������� ���,���,
XY-stage
vacuum chamber
Y-interferometer
reference-mirror
20 cm
X-inter-ferometer
autocollimator
plane mirrorH
eNe-
lase
rSEM
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Results for Cr/quartz-photomask:
� Stuctures with 1 µm CD, 6´´ (150 mm) mask size
� (13 x 13) grid, 10 mm pitch
� 15 repeat measurements
� Differences from mean coordinates
� Statistics of observed differences:
x / µm y / µmmaximum 0,008 0,008minimum -0,006 -0,010mean 0,000 0,000std. dev. (3 s) 0,005 0,007
20 nm
Column
Row
P BP BTT�*�����*���������#��������#��� ���������������� -��.��#���-��.��#�����������������
ContributionsContributions to SE edge to SE edge contrastcontrast ??slopeslopecontrastcontrast
diffusiondiffusion
backback--scatterscatter
beambeamprofileprofile
400 420 440 460 480 500 520 540 560 580 600-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
200
nm
Surface Topography
Sidewall slope: 90° 87° 85° 83°
Fit-Function ex
Sig
nal
[arb
. Uni
ts]
Scan Position [nm]
Monte Carlo Monte Carlo basedbasedsimulationsimulation of edge of edge signalssignalsexampleexample: : influenceinfluence of edge of edge slopeslope
P BP BTT/ �/ ���������������������������))����������������+�01��2�����+�01��2�����������������������
1,900 µm
3,722 µm
500 nm
0 500 nm
I
II
A B C
I II I II I II
EOMS 213 176 293 276 967 964
VERITECT 205 180 281 270 960 961
Measured CD values in nm, compared at top edge positions, differences < 15 nm
VERITECT (AFM) EOMS (LVSEM)
Si: h = 480 nm, DUV-lithography, dry etched
1,900 µm
3,722 µm
P BP BTT$3$3))������#�43�������#�43���������������������������������5����/ �����5����/ ���������
-70
-60
-50
-40
-30
-20
-10
0 200 400 600 800 1000 1200 1400
CD
: D
evia
tio
n f
rom
no
min
al [
nm
]
Nominal CD [nm]
CD instrumentation:LV-SEM, top CD:-
18.1020.1008.11
- UV microscopy
Mean offset: 33 nm
2,500 µm
100 nm
0
Profil
AFM: Edge angle: ≈≈≈≈ 74°
Expected difference betweentopCD and CD at 50% on edge at ARCr layer of 100nm: 30 nm
Isolated opaque lines
AFM characterization
P BP BTT��������������������������������������������*'6������*'6������
•• New PTB standard length comparatorNew PTB standard length comparator
•• Smallest uncertainties achievable by vacuum Smallest uncertainties achievable by vacuum interferometryinterferometry
•• Measurement range: up to 610 mmMeasurement range: up to 610 mm
•• Length calibrations and comparison measurements uncertainty goalLength calibrations and comparison measurements uncertainty goalss
•• Line scaleLine scale UUaimaim ≤≤ 5 nm5 nm (single line detection)(single line detection)
•• Length on photo maskLength on photo mask UUaimaim ≤≤ 5 nm5 nm
•• Linear encoderLinear encoder UUaimaim ≤≤ 3 nm3 nm (multiple line detection)(multiple line detection)
•• Laser interferometerLaser interferometer UUaimaim ≤≤ 2 nm2 nm
•• Larger 2DLarger 2D--objects with width up to 450 mm measurableobjects with width up to 450 mm measurable
P BP BTT��������������������/���������/�������������!��������!��������
Interferometer Beamsplitter
Granite VibrationIsolation
Bellow
Bellow Slide Bridge
Microscope
Scale
Measurement Slide
LinearDrives
P BP BTT��������������������/���������/����������������������������������������� ������������������
scale
microscope
interferometerbeam splitter
measurement slide
movingmirror
fixedmirrors
•• Compensation of thermal dilatation and bending Compensation of thermal dilatation and bending
•• Interferometer arrangement as virtual measurement frameInterferometer arrangement as virtual measurement frame
P BP BTT��������������������/���������/�������������7�����#���7�����#��� ����������������������������
AOMMeasurement
ReferenceLaser
Fibers
Bellow
Beamsplitter
Polarizers
TubesVacuum Chamber
Window
Nd:YAG, 532 nm
P BP BTT��������������������/���������/�������������*������,*������,
InterferoInterfero--metermeter
MicroscopeMicroscopeunitunit
CarriageCarriage
DriveDrive
InstalledInstalledat PTB:at PTB:
Sep. 2000Sep. 2000
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P BP BTT��������������������/���������/��������������������������������� ����������������������
filter inlet
filter inlet
cabin
measurement room
electrical heating
floor
control room
comparator
shielding
ground isolation
Abbe-Building
Surface
2 m
9 m
Cabin Control
room
Measure-mentroom
Groundisolation
Electricalheating
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•• RealizationRealization of angle of angle withwith resolutionresolution of 0.001´´ and of 0.001´´ and uncertaintyuncertainty of 0.005´´of 0.005´´
•• CalibrationCalibration of of devicesdevices and and standardsstandards overover 360° angle and 360° angle and smallsmall anglesangles
•• ExampleExample : : CalibratedCalibrated autocollimatorsautocollimators (U = 0.007´´)(U = 0.007´´) appliedapplied forfor topographytopographymeasurementsmeasurements byby angle angle deflectometrydeflectometry withwith subsub --nmnm uncunc . . (PTB, (PTB, sectionsection 4.21)4.21)
P BP BTT����8������������������������������8��������������������������������������������
•• 14 14 participantsparticipants fromfrom 4 regional 4 regional metrologymetrology organizationsorganizations
•• DurationDuration : 2000: 2000--20032003
•• 2 line 2 line scalescale transfertransfer standardsstandards manufacturedmanufactured byby HEIDENHAINHEIDENHAIN
•• ZerodurZerodur and and quartzquartz substratesubstrate materialmaterial
•• CharacterizationsCharacterizations of of substratesubstrate : thermal : thermal expansionexpansion , , compressibilitycompressibility
Layout:Layout:
P BP BTT7����7�������������������� �'������'����� ����������������������������9���������������9�����
RelaxationRelaxation effectseffects havehave to to bebe takentakenintointo accountaccount at at thethe nmnm--levellevel !!
((herehere observedobserved on a 280 mm on a 280 mm glassglass ceramicceramic))
P BP BTT$���%&%&��$���%&%&���������������������� ������������������������
Scales of Nano3 design are larger (280 mm) than LMS measurement range:
=> measurements in two overlapping, reversed positions necessary
0
2
4
6
8
10
12
14
-100 -50 0 50 100 S
tand
ard
Dev
iatio
n (2
s) [
nm]
Line Scale [mm]
NANO 3 Line Scale 683
0 deg180 deg
Position deviations from linearity Characterization of line edge qualityover 100 µm section of lines asmeasured in stripes of 12.5 µm
-25
-20
-15
-10
-5
0
5
10
15
20
25
-100 -50 0 50 100
Dev
iatio
n fr
om D
esig
n [n
m]
Line Scale [mm]
NANO 3 Line Scale 683
0 deg180 deg
Dev
iatio
n fr
omlin
earit
y[n
m]
P BP BTTDeviationsDeviations fromfrom weightedweighted meanmean valuevalue: : notenote slopeslope differencesdifferences
���������� ���%:&�������%:&������������ ���#���������#���������� �� )) ��������
Nano3, Measurand 1B, Quartz, deviations from weight ed mean
-100
-80
-60
-40
-20
0
20
40
60
80
100
0 40 80 120 160 200 240 280Nominal position / mm
Dev
iatio
n / n
m
PTB, LMS
B
C
D
E
F
G
H
I
J
K
PTB, nmK
P BP BTT���������� ���%:&�������%:&������������ ���#���������#���������������������������� #��#��55
ComparisonComparison withwith weightedweighted meanmean afterafter eliminationelimination of of slopeslope differencesdifferences
Nano3, Measurand 1B, Quartz, linearity deviations, U < 20 nm
-16
-12
-8
-4
0
4
8
12
16
0 40 80 120 160 200 240 280Nominal Position / mm
Dev
iatio
n / n
m
PTB, LMS
B
C
F
I
mean
PTB, nmK
P BP BTT
LMS 2020 Multilateration EOMS Nanometercomparator*
Measurand x-y-coordinates
x-y-coordinates
x-y-coordinates
Length
Uncertainty(k=2)
[(10 nm)² +(0,2 L)²]1/2
[(0,5 µm)² +(0,8 L)²]1/2
[(15 nm)² +(0,08 L)²]1/2
[(4 nm)² +(0,003 L)²]1/2
Meas. range 200 mm 700 mm 300 mm 610 mm
�������������������������������������������� ������������ ��#���#� � �))������������������
P BP BTT1������1���������#���#;;
ShortShort--term needs:term needs:
-- Improvement of probe sample interaction modelling, refinement oImprovement of probe sample interaction modelling, refinement o f models byf models bymeasurements with improved reproducibility on bette r defined rmeasurements with improved reproducibility on bette r defined r eferenceeferencesamples with better known material parameterssamples with better known material parameters
-- Closer cooperation with highCloser cooperation with high --end manufacturing sites to jointly develop betterend manufacturing sites to jointly develop betterstandards which then can be calibrated with smaller uncertaintstandards which then can be calibrated with smaller uncertaint iesies
-- Improvement of cross calibration procedures between different mImprovement of cross calibration procedures between different m etrologyetrologyinstrumentationinstrumentation
-- Further evaluate the potential of (microFurther evaluate the potential of (micro --) ) scatterometryscatterometry methods for inmethods for in --linelineproduction monitoring, comparison with other high r esolution mproduction monitoring, comparison with other high r esolution m icroscopyicroscopy
-- Improvements of high quality graduations (profile l ine shape, sImprovements of high quality graduations (profile l ine shape, s maller pitches)maller pitches)
-- Improvement of AFM measurement speedImprovement of AFM measurement speed
-- MeasurandsMeasurands to take into account 3D shape of isolated or groupe d structuresto take into account 3D shape of isolated or groupe d structures
P BP BTT1������1���������#���#;;
Mid and longMid and long--term needs:term needs:
-- Combination of different probing systems in one ins trument to iCombination of different probing systems in one ins trument to i mprovemprovedirect comparability of measurement resultsdirect comparability of measurement results
-- Combination of stable selfCombination of stable self --assembled structures (locally perfect) withassembled structures (locally perfect) with
globally defined high quality graduationsglobally defined high quality graduations
-- Increase potential of XIncrease potential of X --ray ray interferometryinterferometry for dimensional metrology (speed!)for dimensional metrology (speed!)
-- Increase potential of redundant measurement techniq ues in high Increase potential of redundant measurement techniq ues in high precisionprecisiondimensional dimensional nanometrologynanometrology (like e.g. (like e.g. trilaterationtrilateration , error separation), error separation)
-- Search for and investigate Search for and investigate newnew measurement principles and approaches measurement principles and approaches