Abstract

As extreme ultraviolet (EUV) lithography advances toward high numerical apertures (NAs) of 0.55 and 0.75, mask-3D effects degrade image fidelity, limiting resolution and the process window. This work investigates the performance of alternative EUV absorber materials for sub-12 nm half-pitch patterning under high-NA and hyper-NA conditions. The lithographic simulations were conducted using the PROLITH Maxwell rigorous model under dipole illumination optimized for sub-24 nm resolution dense line/space features. The EUV mask stacks were derived from five fabricated and tested absorbers: TaBN, Ru/Ta, Pt2W, Ni/CrN, and TaSi2.  The absorber thickness was recalibrated to an optimal value, ensuring a maximum normalized image log-slope and a reflectivity of ≤ 2. In addition, imaging performance was quantified using NILS, NILS depth of focus (NDoF), best focus variation (BFV), and threshold-to-size (TtS), along with mask 3D-induced critical dimension error and signed-shift. These findings helped narrow down a suitable candidate for future EUV systems, providing a viable pathway to extend lithography to resolve 6 nm half-pitch. Future work will focus on experimental validation, aperiodic multiplayer optimization, and integration of optical proximity correction and source-mask optimization.

Publication Date

4-2026

Document Type

Thesis

Student Type

Graduate

Degree Name

Microelectronic Engineering (MS)

Department, Program, or Center

Microelectronic Engineering

College

Kate Gleason College of Engineering

Advisor

Bruce Smith

Advisor/Committee Member

Karl Hirschman

Advisor/Committee Member

Stephanie Bolster

Campus

RIT – Main Campus

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