Implications of Polarization, Corner Rounding, OPC Design and OPC Fidelity on Aerial Images

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Implications of Polarization, Corner Rounding,
OPC Design and OPC Fidelity on Aerial Images

• SFR Workshop
• November 8, 1999
• Konstantinos Adam and Prof. Andrew Neureuther
• Berkeley, CA

We use EM theory and rigorous TEMPEST simulations
to investigate photomask technology issues.
Current investigations include scattering bars,
polarization effects corners, interior versus
exterior OPC features, placement and corner
rounding.
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Scattering Bar Simulation with TEMPEST
CDtarget130nm
Mag4X
l193nm
Ey
TE Ey polarization
Ex
TM Ex polarization
mm
mm
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Scattering Bar Aerial Images
l193nm, NA0.7, s0.6, Mag4X, CDtarget130nm
Aerial Image (Best focus)
Normalized Intensity
(mm)
- Observe that the scatter bars (also the main
feature) appear wider in TM excitation than in TE
and narrower with SPLAT simulation (scalar theory)
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SB Design Graphs
Intensity dip of SB
CD Control with SB Size Control
Intensity
CD (nm)
Size of SB (l/NA)
Size of SB (l/NA)
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Corner Rounding (Clear Field Mask) - Ey Near
fields
l193nm
Mag4X
CDtarget130nm
Eincident (TE)
Eincident (TE)
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Corner Rounding Design Graph
- LES increase versus radius of curvature is
quadratic, i.e. it is proportional to the area
missing from the corner due to the roundness
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External OPC Ey Near Fields
Example 0.1l/NA Square OPC and Mouse Ear OPC
with radius0.06l/NA
Reference
Square OPC
Mouse Ear OPC
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OPC Design Graph
25
Square OPC
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Mouse ear OPC
Data for OPC dispaced along the diagonal
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LES correction in nm
10
5
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
x10-3
non-overlapping area in mm2 (1X)
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Targeted Opportunities in Photomasks and Optics
for 2000-2002

• Attenuating phase-shifting masks
• high refractive index and physical height of the
  attenuating material adversely influences light
  in adjacent areas.
• Alternating phase-shifting masks
• 3D problematical structures - resonate ridges and
  cross-talk between features inside the photomask.
• Phase-shifting mask repair
• guidelines for adequate repair - height, slope,
  river bed, stain.
• Optics
• role of laser bandwidth in image quality.
• high NA thin-film polarization effects.