Deposition of high-density carbon layer for beyond EUV lithography

In 2019, EUV lithography technology with a wavelength of 13.5 nm was applied to the mass production of logic devices at the 7 nm+ node. As the demand for advanced semiconductor devices, beyond EUV(BEUV) lithography technology, which operates at exposure wavelengths around 6.7 nm, is expected to become the next generation lithography. The development of multilayers with high reflectivity and high stability is critical issue for the BEUV lithography. La/B-based multilayers have been reported with high reflectivity. However, the reflectance stability of La/B-based multilayers is an issue due to the inherent reactivity of La material. We proposed carbon/boron (C/B) multilayers in BEUV lithography. The C/B multilayer has high theoretical reflectivity and wide bandwidth, which is comparable to the La/B-based multilayer. The bandwidth of C/B multilayer depends on carbon film density. Consequently, the deposition of high-density carbon films is important to achieve high-performance C/B multilayers for BEUV lithography. Thus, we developed a new magnetron sputtering tool with unbalanced magnetron cathodes to investigate the deposition condition optimization.