Transcript Introduction

1
Automated Characterization
of Optical Image Quality
SFR Workshop
November 8, 2000
Andrew R. Neureuther and Kostas Adam
Berkeley, CA
2001 GOAL: Complete initial simulations and experiments
sufficient to design polarization masks and multi-parameter test
structures 9/30/2001.
11/8/2000
2
Motivation: Multi-Parameter Test Structures
Combine automated (optical and/or SEM) wafer
inspection with simulation interpretation of results.
• Simulation design of test mask artifacts and
characterization procedures
– 3-5X enhanced sensitivity with 2-3 x reduced confounding
– Half-Tone phase edges, phase dots, adjacent defects
– Focus/dose behavior, PEB time, Resist A/B, additive partial
clear field exposures, etc.
• Inspection:
– Presence or absence of resist remaining, linewidth, bridging
– Assign causes through statistical analysis
11/8/2000
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Defect-Probe Based Aberration Targets: Concept
0.5 l/NA
l/NA 180o
0.6 l/NA 0.4
Sq. Defect
Line
Sidelobe
Detect Sidelobe by over exposing 2.5x
and using automatic wafer inspection
11/8/2000
The 0.4 l/NA by 0.4 l/NA
programmed 180o phase defect
provides an interferometric like
reference electric field with
magnitude 0.43 and phase of
180o compared to the clear area
field.
Coma
Sidelobe
-0.1 wave => 0.40
0.0 wave => 0.30
0.1 wave => 0.21
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Defect-Probe Based Aberration Targets: Design
Example for coma
1) Characterize the Point Spread Electric Field
Pin Hole
PS Electric Field
2) Inverse Map PSEF to locate target components
Defect Probe
Target Components
3) Add target components to reduce confounding
Added Components that
reduce Astigmatism and
Spherical Aberration
o
o
1 at 0
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1 at 180
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Defect-Probe Based Aberration Targets: Layout
Dark Field Patterns
Grid is 0.1 l/NA
Probe
Astigmatism
Spherical
1 at 90o
Trefoil
Coma
1 at 0o
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1 at 180o
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Defect-Probe Based Aberration Targets: Trefoil
0.366
Sensitivity
0.190
No Aberration
- Trefoil
0.068
+ Trefoil
Orthogonality
0.181
0.167
Defocus
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0.192
Astig (cos)
0. 182
- Coma (cos)
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Defect-Probe Based Aberration Targets: Spherical
Sensitivity
0.044
0.191
- Spherical
No aberration
Orthogonality
0.569
0.391
+ Spherical
0.010
High sensitivity to
spherical but poor
orthogonality to defocus.
- Defocus
11/8/2000
+ Defocus
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Defect-Based Aberration Target: Data Summary
Individual Zernike’s
Target
Coma
Astig
Trefoil
Spherical
Halftone
None => Reference
0.226
0.236
0.190
0.191
0.135
Defocus D
-0.011
-0.023
-0.181
Astig(sin) D
-0.013
-0.011
+0.000
Astig(cos) D
-0.017
-0.009
-0.001
Coma(sin) D
-0.006
-0.007
+0.000
Coma(cos) D
-0.137
+0.002
-0.067
Trefoil(sin) D
+0.073
-0.008
Trefoil(cos) D
-0.011
-0.122
Spherical 3rd D
+0.027
-0.023
Set of
Zernike’s
+0.259
+0.200
Defect-Probe Intensity
Astigmatism
Astigmatism
0, 180 Flip
Trefoil
No Aberrations
0.236
0.236
0.227
Production Tool
0.096
0.423
0.237
Difference
-0.140
+0.187
+0.010
~ 0.1l Astig
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-0.005
< 0.01 Trefoil
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2002 and 2003 Goals
Conduct and quantitatively interpret polarization masks, and
multi-parameter test structures, by 9/30/2002.
Define apparatus, specify testing procedures, and interpret data
for polarization masks, and multi-parameter test structures, by
9/30/2003.
Polarization Masks
Polarization
orthogonal
spillover
Phase-shifted
spillover
Reduced Proximity
Phase
Polarization
adjusted
Shift half-tone Half-Tone
Masks to be made by nanoimprint lithography with UTA.
11/8/2000