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SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 1Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH, Inc. SEMATECH, the SEMATECH logo, Advanced Technology Development Facility, ATDF, and the ATDF logo are registered servicemarks of SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners.
Benchmarking EUV Mask InspectionBeyond 0.25 NA
The SEMATECH BerkeleyActinic Inspection Tool
A I TAn EUV-wavelength
mask inspection microscope
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 2
"1%"depth
bi-layers
13.4 nm 215 nm 31
488 nm 53.6 nm 8
266 nm 20.6 nm 3
EUV light penetrates deeply into the resonant ML structure.
488-nm and 266-nm light barely reaches below the surface.
Field Penetration for three s
0.01
1.00
depth [nm]
Field intensity vs. depth
At-wavelength testingprobes the actualmultilayer response.
Different wavelengths see the same ML structuredifferently
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 3
Upgrades Resolution (Uniformity)
Aberrations Modeling, Measurement, Reduction
Linewidth Measurement, Repeatability
LBNL: Kenneth A. Goldberg,Iacopo Mochi, Patrick Naulleau
AMD: Bruno LaFontaine
Samsung: Hakseung Han
SEMATECH: Sungmin Huh
Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH, Inc. SEMATECH, the SEMATECH logo, Advanced Technology Development Facility, ATDF, and the ATDF logo are registered servicemarks of SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners.
Benchmarking EUV Mask InspectionBeyond 0.25 NA
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 4
AIT: An EUV Zoneplate Microscope
= 13.4 ± 0.01 nm, tunable
{0.25, 0.30, 0.35} NA (4x)
907x–1000x mag
25–35 sec/exposure
250 images / 8h
Si3N4
5 lenses—different mag and NA
CCD
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 5
2007 2008 20080.25 NA 0.25 NA 0.35 NA (4x)
100 nm (mask)lines25 nm(wafer)
New CCD + higher mag = higher contrast.Higher-NA lens Improved resolution.
EIP
BN
200
8
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 6
Contrast Transfer Function (CTF)We now achieve much higher contrast below 225 nm hp
150 nm lines
2008
2008NA
2007
25 50 75 100 125Mask [nm]
4x [nm] 0
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 7
Improving performance through alignment
The off-axis zoneplates have asmall field of view, 5–8 µm,so alignment is critical.
alignment(aberration
minimization)
imagingperformance
detailedfeedback
through-focusimage analysis
Accurate measurement of contrast, defects, line-width, etc.all rely on low aberrations.
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 8
175 nm Contacts32-µm-wide area
5 µm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 9
175 nm Contacts16-µm-wide area
2 µm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 10
175 nm Contacts8-µm-wide area
1 µm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 11
Through-focus, contacts reveal aberrations clearly
0.8
µm
1.26 µmz steps
0.80 µm z steps
focus
0.8
µm
Au
gu
stA
pri
l ’08
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 12
Through-focus, contacts reveal aberrations clearlyA
ug
ust
Ap
ril ’
08
0.8
µm
0.8
µm
AstigmatismAstigmatic Displacement (AD) ≥ 2.0 µm (125 nm wafer)
RMS Wavefront Error ≥ 0.23 Waves RMS
AstigmatismAstigmatic Displacement (AD) ≥ 0.3 µm (19 nm wafer)
RMS Wavefront Error ≥ 0.08 Waves RMS
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 13
Models help assess our position within the field
Zoneplate field of viewField-dependent Astigmatism Model
MeasuredAstigmatism
22 µmone image
0.0
0.2
0.4
0.6
0.8
Waves RMS
Please seeI. Mochi, et al.
EUVL Symposium 2008
54 µm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 14
Testing line-width measurement capabilities
• 1:1 lines intensity-threshold reference.• 10 regions per image through-focus.• LW based on best-focus images.
• through-focus 10x per location.• 10 regions per image.• best focus = highest contrast.• Assume 1:1 lines, calculate a global “best threshold” value. Statistics.
Mask: MET-3 M0408-01AMD/IFX/AMTC
Mask: PDM-AIT[1]Samsung/SEMATECH
1. Measuring biased lines
2. Repeatability testing with 1:1 lines
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 15
Measuring Biased Lines
Mask: MET-3 M0408-01, AMD/IFX/AMTC
500
nm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 16
Mask CD 350
Measuring CD from biased lines — 1000 nm pitch
1 µm
400 450 500 550 600 650 nm
reference
16.1 nm (mask)4.0 nm (wafer)3
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 17
Programmed-defect arrays—aerial images
176 nmmask
44 nm4x, ADT
35 nm5x, MET
176 nm1 µm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 18
132 nmmask
33 nm4x, ADT
26 nm5x, MET
Programmed-defect arrays—aerial images
1 µm
132 nm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 19
110 nmmask
28 nm4x, ADT
22 nm5x, MET
Programmed-defect arrays—aerial images
1 µm
110 nm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 20
88 nmmask
22 nm4x, ADT
18 nm5x, MET
Programmed-defect arrays—aerial images
1 µm
88 nm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 21
94 ± 1%
Measurement Repeatability Testing—176 nm lines
1 µ
m
176 nmmask
44 nm4x, ADT
35 nm5x, MET
6.8 nm (mask)1.7 nm (wafer)3
Test #
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 22
Measurement Repeatability Testing—132 nm lines
132 nmmask
33 nm4x, ADT
26 nm5x, MET
1 µ
m
88 ± 1%
6.0 nm (mask)1.5 nm (wafer)3
Test #
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 23
Measurement Repeatability Testing—110 nm lines
1 µ
m
110 nmmask
28 nm4x, ADT
22 nm5x, MET
74 ± 4%
3.7 nm (mask)0.9 nm (wafer)3
Test #
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 24
70 ± 6%
Measurement Repeatability Testing—88 nm lines
8.0 nm (mask)2.0 nm (wafer)
1 µ
m
88 nmmask
22 nm4x, ADT
18 nm5x, MET
3
Test #
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 25
Measurement Repeatability Testing Summary
Mask CD
idea
lContrast Transfer Function CD Measurement 3
0.5
0.0
1.0
1.5
2.0
2.5
3.0
8822
6.86.0
3.7
8.0
12.5 25 37.5 50 Wafer (4x) 12.5 25 37.5 50
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 26
Through-focus analysis of 180 nm CD (mask) lines
Defocus Z [µm] best
LW Uncertainty 3nm
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 27
Linewidth: Main Issues and solutions
• Signal-to-noise ratioMeasurement dependence on exposure time
• Illumination uniformityX-Scanning illuminator; soon XY scanning
• System stabilityMask lateral shift during z motionaffects illumination and aberrationsImproved Z actuator, -scan method
• Zoneplate and illumination alignmentHow stable and repeatable can we make it?What sorts of feedback are available to correct it?Characterizing aberrations, refining alignment
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 28
Conclusion
• System upgrades:improved resolution, contrast, 0.35 NA (4x)
• Aberrations: reduced by alignment & analysisAstigmatism is down,from 0.23 to 0.08 RMS
• Contrast: 71% for 88-nm lines(22 nm 4x)
• Linewidth 3: Repeatability~5 nm 3(1.25 nm on wafer)
• More improvements will come froma combination ofhardware & software solutions.
• System upgrades:improved resolution, contrast, 0.35 NA (4x)
• Aberrations: reduced by alignment & analysisAstigmatism is down,from 0.23 to 0.08 RMS
• Contrast: 71% for 88-nm lines(22 nm 4x)
• Linewidth 3: Repeatability~5 nm 3(1.25 nm on wafer)
• More improvements will come froma combination ofhardware & software solutions.
SPIE Photomask BACUS 2008KAGoldberg @ lbl.gov SEMATECH Berkeley Actinic Inspection Tool 29
1 µm
Special Thanks!
CXRODavid Attwood
Seno RekawaDrew KempNathan Smith
Paul DenhamErik Anderson
Bob GunionEric GulliksonRon Tackaberry
For More Information: http://Goldberg.LBL.Gov
