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Polarization Masks: Concept and Initial Assessment

SFR WorkshopNovember 14, 2001

Michael Lam and Andrew NeureutherBerkeley, CA

2001 GOAL: Complete initial simulations and experiments sufficient to design polarization masks and multi-parameter test

structures 9/30/2001

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Motivation: Polarization is a New Lever

• By rotating the polarizations by 90 degrees, the electric fields add as orthogonal vectors rather than co-linear vectors and thereby reduces the undesired intensity by a factor of 2

• Problematic co-linear subtraction at phase edges of phase-shifting masks is converted to vector addition of spatially orthogonal fields, reducing the effect to a 90 degree transition

• Structures can be made to examine quality of polarization.

Polarization orthogonal spillover

Phase-shifted spillover

Polarization adjusted half-tone

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Simulation Approach

2D Tempest near field results

Photomaskpolarization bar test geometries

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Near Fields for Polarization Bars with 3 Gaps

Note that the intensities below the mask are larger for the outboard openings

Contour Plots (Ex) Cutlines (Ex at node z = 12)

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Effect of Gapwidth on Polarization and Transmission

• Cross polarization (Ey) transmission is small, but quickly rises as gapwidth increases.

• Good transmission of desired polarization (Ex) vs. cross polarization (Ey)

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Novel 3D Cross Pattern for Polarization Contacts

Through the use of polarization, the imaging of a normally square contact can be converted to the single exposure of two orthogonal line patterns which can be more easily resolved.

Square Contact

Sequential Exposure of H and V Lines to Form a Smaller Contact

Simultaneous Exposure with Polarization Contact

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3D Cross Pattern, Near Fields in Arm

Very little cross polarization (Ey) is generated from the structure.

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3D Cross Pattern, Near Fields in Center

Initial Results show that more cross polarization is generated near the center and the transmitted field is slightly non uniform.

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2002 and 2003 GoalsConduct 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.

• Studies of the number of gaps and chrome materials• Link the near fields to aerial imaging in SPLAT• Explore novel planar structures and dielectrics