[17a-S4_202-1~10] 7.3 Micro/Nano patterning and fabrication

9:30 AM - 9:45 AM JST(12:30 AM - 12:45 AM UTC)

[17a-S4_202-3] La/B₄C Reflective Multilayer Films Dependence on Ar⁺ Acceleration Voltage

〇Takeo Ejima¹, Nakano Ryuki¹, Ryosuke Nakamura¹, Tadashi Hatano¹ (1.Tohoku Univ.)

Keywords:

Reflection multilayer,BEUV,Ion supttering

The beyond extreme ultraviolet (BEUV) wavelength region around 6.x nm has been proposed for next-generation semiconductor lithography, where reflective multilayer mirrors are essential. In this study, we focus on La/B₄C multilayers as an alternative to the conventional LaN/B system, which requires reactive sputtering. Owing to the thermodynamic stability of both La and B₄C, sharp interfaces are expected. A multilayer consisting of 150 periods with equal layer thicknesses of 1.72 nm was designed, yielding a calculated reflectance of 0.74 at a wavelength of 6.72 nm and an incidence angle of 15°. Samples were fabricated by ion-beam sputtering under different acceleration voltages. X-ray reflectivity measurements revealed similar periodic structures among the samples, while differences in interfacial structure were suggested. Clear reflectivity signals were successfully obtained in BEUV reflectance measurements.