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 Karl Franzens University Graz

Graz University of Technology 

Optical and EUV Lithography: Enablers of continued semiconductor scaling
PD Dr. Andreas Erdmann
Fraunhofer IISB Erlangen
16:15 - 17:15 Tuesday 17 October 2023 

The size of the smallest features on nanoelectronics circuits is governed by the Abbe-Rayleigh criterion k1 lambda / NA, where lambda stands for the wavelength of the used light, NA is the numerical aperture and k1 is a technology-dependent factor. We briefly discuss the consequences of this criterion for the development of semiconductor lithography over the past decades. DUV immersion lithography with wavelength of 193 nm and NA of 1.35 has enabled the fabrication of features sizes below 50 nm. Optical- and material-driven resolution enhancements including off-axis illumination, optical proximity correction (OPC), phase shift masks, source-mask optimization (SMO) and double patterning enable the required k1 values below 0.4.
The latest generation of computer chips employs extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm. Although the small wavelength promises a much better resolution compared to DUV lithography, the used reflective projection optics and reflective masks introduce several imaging artifacts like non-telecentricities, various contrast-loss mechanisms and feature dependent shifts of the best focus position. We employ dedicated modeling techniques to understand and optimize the image formation in high EUV lithography with a NA of 0.55. We will demonstrate that the guiding of light in novel absorber materials with low refractive index, so called low-n absorbers, enables efficient imaging solutions with feature sizes around 10 nm.