Extreme ultraviolet interference lithography
Eventually small features of semiconductor devices will decrease below 10 nm and for many applications high density structures will be required. For such tasks alternative approaches to utilize short wavelength extreme ultraviolet (EUV) radiation may be considered, such as EUV interference lithography (IL) or proximity printing.
Compared to other nano-patterning methods EUV-IL includes benefits such as no charging, negligible photoelectron blur effect and high throughput. Reducing the period down to sub 20 nm is challenging, since the half-pitch of the required transmission masks starts to be comparable with the wavelength of radiation, and the standard Kirchhoff approach for the mask description cannot be used anymore. As a result, laboratory EUV-IL requires a careful consideration and optimization of optics and source parameters in the interference system, as well as rigorous computation of the light diffracted by the mask.
The diffraction and interference of EUV radiation, with the aim to obtain interference patterns with sub 20 nm resolution and sufficient contrast, has been considered to be an impressive candidate. Numerical and analytical calculations, design of required diffractive elements and the investigation of quantum coherence effects on the nano-scale, as well as exposure experiments, resist studies and characterization of resulted nano-structures, will be studied.
Hyun-su Kim received his bachelor’s degree in physics from Gachon University, South Korea, and his master’s degree in nano-science from Hanyang University, South Korea. Since 2010, he has been working at the EUV group of RWTH Aachen University and the Fraunhofer Institute for Laser Technology, Germany and the Optoelectronic Research Center (ORC) in University of Southampton, UK as a PhD researcher supported by the EU Erasmus Mundus doctoral program (Extreme- Ultraviolet and X-ray Technology and Training for Interdisciplinary Cooperation, EXTATIC).
During his master’s study, his research included the photo-resist simulation using Monte-Carlo method for EUV lithography. At the moment, his research interest includes the mask-based proximity printing in Fresnel diffraction regime and developing the EUV interference lithography with laboratory EUV sources such as discharge plasmas, high harmonic generation and a capillary discharge laser.