1. Scatterfield 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.
A new method which combines the best attributes of:
Optical microscopy
magnification, image forming optics, engineered illumination fields
Optical scatterometry
superb sensitivity, statistical averaging, single angle of illumination

2. Scatterfield Microscopy
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 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.

3. Scatterfield Microscopy
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 optical imaging enables the microscope to be characterized in fundamental ways previously inaccessible allowing substantially improved theoretical understanding of optical microscope imaging.

4. Tool Configuration: Illuminator Layout
LED
aperture
relay lens
objective
Condenser
Back focal plane
of condenser lens
Field Lens A B C
Even illumination
at the object focal plane
Field Diaphragm
Scan axis configuration
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.

5. Optical Modeling: Theory to Experiment Agreement
Sensitivity: 100 nm CD, Pitch 300 nm
Best Fit for 100 nm CD, Pitch 600 nm
(0,0) Die:
Top = nm Mid = nm
Bottom = nm
(0,-1) Die:
Top = nm Mid = nm
Bottom = nm
(-1,-1) Die:
Top = nm Mid = nm
Bottom = nm
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.
Quantitative agreement obtained for optical modeled measurements.
Optical/AFM agreement on the nanometer scale achieved for the first time.

6. Overlay/CD Targets: Parallel Measurement Capabilities
Line/trench
structures
90nm 1:3
Linearity Array
Zero 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.

7. Scatterfield Zero Order Imaging
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