Hole-Patterned Pellicles: A Structural Approach for Improved Extreme Ultraviolet Transmittance and Mechanical...

Area of Science:

• Semiconductor Manufacturing
• Materials Science
• Optical Engineering

Background:

• High-throughput extreme ultraviolet (EUV) lithography demands pellicles with optimal transmittance.
• Conventional pellicle optimization methods (material choice, thinning) are reaching practical limits.
• Alternative architectures are needed to overcome current limitations.

Purpose of the Study:

• Investigate a hole-patterned pellicle architecture as an alternative to continuous films.
• Analyze the impact of geometric design on EUV transmittance and mechanical properties.
• Provide design-relevant trends for advanced pellicle development.

Main Methods:

• EUV transmittance measurements to correlate with open ratio (OR).
• Pseudo-spectral time domain (PSTD) simulations for structural and optical analysis.
• Lithographic aerial-image simulations to assess pattern distortion.
• Mechanical bulge tests for pressure-deflection and failure analysis.

Main Results:

• Transmittance increases with OR, aligning with theoretical models but showing deviation at high OR.
• Pattern distortion is minimal except under highly coherent illumination, suppressed by increasing radius sigma.
• Hole-patterned membranes show altered pressure-deflection behavior and narrower failure distributions.
• Periodic perforation influences transmittance and mechanical response.

Conclusions:

• Hole-patterned pellicles offer a viable geometric design strategy for EUV lithography.
• This approach complements existing material and thickness optimization techniques.
• The study provides key insights into the trade-offs between transmittance, mechanical integrity, and defect sensitivity.