Material-specific high-resolution table-top extreme ultraviolet microscopy

TL;DR

This paper introduces a high-resolution, material-specific EUV microscopy technique at 13.5 nm wavelength, combining a stable EUV source with advanced ptychography to achieve 16 nm resolution and material classification of complex structures.

Contribution

It presents a novel table-top EUV microscopy setup with structured illumination and a new ptychography method for robust, high-resolution, material-specific imaging.

Findings

Achieved 16 nm lateral resolution in EUV microscopy.

Demonstrated material classification of semiconductor structures.

Enabled detailed 3D imaging of complex nano-structures.

Abstract

Microscopy with extreme ultraviolet (EUV) radiation holds promise for high-resolution imaging with excellent material contrast, due to the short wavelength and numerous element-specific absorption edges available in this spectral range. At the same time, EUV radiation has significantly larger penetration depths than electrons. It thus enables a nano-scale view into complex three-dimensional structures that are important for material science, semiconductor metrology, and next-generation nano-devices. Here, we present high-resolution and material-specific microscopy at 13.5 nm wavelength. We combine a highly stable, high photon-flux, table-top EUV source with an interferometrically stabilized ptychography setup. By utilizing structured EUV illumination, we overcome the limitations of conventional EUV focusing optics and demonstrate high-resolution microscopy at a half-pitch lateral resolution of 16 nm. Moreover, we propose mixed-state orthogonal probe relaxation ptychography, enabling robust phase-contrast imaging over wide fields of view and long acquisition times. In this way, the complex transmission of an integrated circuit is precisely reconstructed, allowing for the classification of the material composition of mesoscopic semiconductor systems.