scatterfield zero order imaging dr. r. m. silver, dr. r. attota, and dr.r. larrabee extending...
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![Page 1: Scatterfield Zero Order Imaging Dr. R. M. Silver, Dr. R. Attota, and Dr.R. Larrabee Extending optical measurement limits well beyond conventional expectations](https://reader030.vdocument.in/reader030/viewer/2022032709/56649eb05503460f94bb6427/html5/thumbnails/1.jpg)
Scatterfield Zero Order ImagingScatterfield Zero Order Imaging
Dr. R. M. Silver, Dr. R. Attota, and Dr.R. Larrabee
Extending optical measurement limits well beyond conventional expectations using engineered illumination.
• Optical microscopy– magnification, image forming optics,
engineered illumination fields
• Optical scatterometry– superb sensitivity, statistical averaging,
single angle of illumination
A new method which combines the best attributes of:
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Scatterfield optical imaging: Measuring 10 nm or 20 nm sized features with 450 nm wavelength light. Well beyond conventional resolution limits using engineered illumination and structured targets.
• Primary Semiconductor Applications– Critical Dimension (CD) metrology– Overlay metrology– Defect inspection
• Nanomanufacturing Applications– Fuel cell process control– Arrayed nanoparticles– Nanometer sensitivity
• A technique which enables scatterometry type measurements on very small targets– High throughput, low cost– In chip semiconductor applications– Reduced scribe line target size– Parallel measurements of multiple targets
Scatterfield Microscopy
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Scatterfield optical imaging enables the microscope to be characterized in fundamental ways previously inaccessible allowing substantially improved theoretical understanding of optical microscope imaging.
• Angle resolved characterization is fundamental to accurate microscopy
– Optical system alignment – Polarization characterization– Angular transmissivity – Source characterization
• Nanometer scale measurements can be achieved using angle resolved scatterfield microscopy.
– Quantitative modeling demonstrated– Nanometer consistency with reference metrology– Dense zero order arrays can be measured– No immediate limitation of feature size or density
Scatterfield Microscopy
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Tool Configuration: Illuminator LayoutTool Configuration: Illuminator Layout
• 1 cm diameter conjugate back plane for illumination engineering.
• Fourier plane engineering on illumination and collection paths.
• Can define x and y polarization.• y (parallel) and x (perpendicular) scan axes relative to target
lines.
LED
aperturerelay lens objective
xsample
sampley
xsample
sampley
Scan axis configuration
Condenser
Back focal planeof condenser lens
Field L
ens
ABC
A
B
C
Even illuminationat the object focal plane
Field Diaphragm
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Sensitivity: 100 nm CD, Pitch 300 nmSensitivity: 100 nm CD, Pitch 300 nm
(0,0) Die:Top = 118.6 nmMid = 114.7 nmBottom = 128.8 nm
(0,-1) Die:Top = 116.1 nmMid = 112.3 nmBottom = 125.1 nm
(-1,-1) Die:Top = 102.1 nmMid = 117.0 nmBottom = 128.9 nm
Best Fit for 100 nm CD, Pitch 600 nmBest Fit for 100 nm CD, Pitch 600 nm
• Quantitative agreement obtained for optical modeled measurements.• Optical/AFM agreement on the nanometer scale achieved for the first time.
Optical Modeling: Theory to Experiment Agreement
Plots show intensity as a function of angle. Experimental sensitivity on the left and theory to experiment comparison on the right. These data are an example of zero order imaging with sub-resolution features.
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Overlay/CD Targets: Parallel Measurement CapabilitiesOverlay/CD Targets: Parallel Measurement Capabilities
Line/trench structures90nm 1:3
-40 -30 -20 -10 0 10 20 30 400
0.2
0.4
0.6
0.8
1
1.2
Linearity - p-polarization
Incident Angle (degrees)
Inte
nsity (
Rela
tive t
o B
ackgro
und) A
B
C
Linearity ArrayZero order 50 nm CDs
• The lines are approximately 60 nm CD +/- 5 nm.• 5 nm changes in linewidth show significant response.• Meets important needs of combined CD and overlay
metrology.• In chip metrology capabilities.
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Summary: Low cost high, throughput technique with applications in process control and metrology for semiconductor manufacturing and emerging nanotechnology industries. Can measure sub-20 nm sized features, densely positioned with nanometer scale accuracy over very large areas.
Patent Application, serial # 11/866,589 filed 11/1/07
Scatterfield Zero Order ImagingScatterfield Zero Order Imaging