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

## TL;DR

This paper introduces a new pellicle design with holes that improves EUV transmittance and mechanical performance for lithography.

## Contribution

The study proposes a novel hole-patterned pellicle architecture with structural advantages over traditional continuous-film designs.

## Key findings

- Transmittance increases with open ratio but deviates at higher ratios due to geometric effects.
- Hole-patterned pellicles show earlier pressure saturation and altered burst-failure behavior in mechanical tests.
- Pattern distortion is minimized with larger radius sigma under coherent illumination.

## Abstract

To sustain high-throughput extreme ultraviolet (EUV) lithography, pellicles with high transmittance are essential. As conventional methods—such as material optimization and membrane thinning—have reached their practical limits, alternative strategies are now required. In this study, we investigate an alternative hole-patterned pellicle architecture that introduces a geometric degree of freedom beyond that of continuous-film architectures. EUV transmittance measurements show that transmittance increases with open ratio (OR), following the absorption-limited trend predicted by an OR-based upper bound model, while exhibiting a measurable deviation at higher OR. To provide structural insight into this deviation, pseudo-spectral time domain (PSTD) simulations were performed under scanner-relevant numerical aperture and illumination conditions, solely to extract qualitative angular redistribution trends associated with hole geometry. Lithographic aerial-image simulations indicate that pattern distortion effects emerge only under highly coherent illumination and are suppressed as radius sigma σr increases. Mechanical characterization using bulge tests reveals distinct pressure–deflection behavior in hole-patterned membranes compared with continuous films, including earlier pressure saturation and modified burst-failure statistics. Although a modest reduction in mean burst pressure is observed, the hole-patterned membranes exhibit a narrower failure distribution, reflecting altered defect sensitivity. Taken together, the results demonstrate how periodic perforation influences transmittance behavior and mechanical response, providing design-relevant trends that complement existing material- and thickness-based pellicle optimization approaches.