Paper 13115-19
Paper 13115-19
EUV Imaging of Nanostructures without Lenses (Invited Paper)
19 August 2024 • 2:40 PM - 3:10 PM PDT
Abstract
With the aim of EUV imaging of nanostructures, a table-top EUV beamline has been constructed, for which the concept of lensless imaging, also known as ptychography, has been developed. The beamline is built around a high-harmonic generation (HHG) source. The coherent quasi-monochromatic EUV light is focused on the sample by an ellipsoidal mirror. Since our application is mainly directed towards wafer metrology for lithography, we adhere to a reflection set-up: the EUV light is scattered by the nanostructures at the surface of the sample, and is reflected towards a camera, where a far-field diffraction pattern is recorded. A data-set comprising a multitude of these diffraction patterns is generated for partially overlapping positions of the focused probe on the sample. Such a data-set provides the necessary redundancy for phase retrieval of the complex-valued field of the sample. Our ptychography algorithms have been developed within an automatic differentiation framework. The multiple challenges from concept and design towards experiment and application will be addressed.
Presenter
ASML Netherlands B.V. (Netherlands)
Wim Coene received the PhD degree in physics from the University of Antwerp in 1986, for his research on computational modeling of electron diffraction and image formation in a high-resolution transmission electron microscope (TEM). He joined the Philips Research Laboratories in Eindhoven in 1988, where he worked on phase-retrieval methods in TEM devised for digital correction of electron-optical aberrations. In 1996, he started to work on channel coding and signal processing for future generations of optical storage like near-field recording and 2D optical storage. He joined ASML Netherlands B.V. in Veldhoven in 2007, where he is currently Director of Research. Since 2015, he is also part-time Professor at the Delft University of Technology. In his combined assignment at TU-Delft and ASML, his scientific interests have been directed towards optical metrology for nanolithography in the semiconductor industry, with a focus on computational imaging, inverse problems and phase retrieval.