EMA modelled alternative EUV absorber materials considering optical and stability behavior

Rajiv N. Sejpal; Bruce W. Smith

doi:10.1117/12.2600735

12 October 2021 EMA modelled alternative EUV absorber materials considering optical and stability behavior

Rajiv N. Sejpal, Bruce W. Smith

Proceedings Volume 11855, Photomask Technology 2021; 118550G (2021) https://doi.org/10.1117/12.2600735
Event: SPIE Photomask Technology + EUV Lithography, 2021, Online Only

Abstract

Alternatives to Ta-based absorbers are being considered for next generation lithography nodes to reduce 3D mask effects and to improve image modulation through phase interference. Low complex refractive index (n – ik) materials can provide phase shifting behavior at thicknesses less than those needed for conventional absorbers, essentially acting as attenuated phase shift mask (attPSM) films. Identifying attPSM absorber thickness and consequent phase requires determining optimum phase shift mask reflectance. Imaging with absorbers at high reflectance show better imaging performance. The absorber thickness is determined where the interference effects lead to high absorber reflectivity. Low refractive index (n) materials are therefore desired as candidate attPSM absorbers. Low – n material combinations identified using Wiener bounds and Effective media approximation (EMA) modelling are optimized for NILS and MEEF using absorber reflectivity on line-space and contact-holes patterns. Absorber candidates at optimum thickness for contact holes are compared with conventional Ta-based absorber using reflected nearfield intensity imaging.

Conference Presentation

Citation Download Citation

Rajiv N. Sejpal and Bruce W. Smith "EMA modelled alternative EUV absorber materials considering optical and stability behavior", Proc. SPIE 11855, Photomask Technology 2021, 118550G (12 October 2021); https://doi.org/10.1117/12.2600735

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