This article is cited in 2 papers

Physical science of materials

Comparative study of the thermal stability of Be-based extreme ultraviolet pellicles

S. Yu. Zuev, A. Ya. Lopatin, V. I. Luchin, N. N. Salashchenko, D. A. Tatarskii, N. N. Tsybin, N. I. Chkhalo

Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhny Novgorod, Russia

Abstract: We demonstrate the possibility of manufacturing Be-based ultrathin films with high transmission at wavelengths of 11.4 and 13.5 nm. For free-standing films of Be and Be-based multilayer structures (Si/Be, ZrSi$_2$/Be, Be/Be$_x$N$_y$, Zr/Be, Ru/Be, Mo/Be), we determine the thresholds of the absorbed power at which over a short period (tens of minutes) of vacuum annealing, initially sagging free-standing films became visibly stretched over the hole. Of the film structures tested here, the Be/Be$_x$N$_y$ structure (with beryllium nitride interlayers) showed the highest threshold for the absorbed power (1 W/cm$^2$). However, due to the low strength of this structure, ZrSi$_2$/Be, Mo/Be, and Be films seem to be more promising for the manufacture of a full-size pellicle. Long-term vacuum annealing of Mo/Be and Be ultrathin films showed that they could withstand 24 hours of vacuum heating at an absorbed power density of 0.2 W/cm$^2$ (film temperature 250$^\circ$C) without noticeable changes in EUV transmission or sagging of films. With comparable transmission ($\sim$83% at 13.5 nm and $\sim$88% at 11.4 nm), a multilayer Mo/Be structure with a thickness of 30 nm appears to be preferable, as it shows less brittleness than a monolayer Be film with a thickness of 50 nm.

Keywords: Be-based pellicle, multilayer thin film, EUV lithography, thermal stability.

Received: 28.06.2021
Revised: 26.08.2021
Accepted: 31.08.2021

DOI: 10.21883/JTF.2022.01.51857.197-21

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