EUV metrology



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EUV spectrometry

At the chair TOS, a compact EUV spectrometer was developed for EUV metrology tasks, a worldwide unique setup using a compact discharge-produced plasma EUV radiation source. The setup can be used to perform various metrological tasks:

  1. Material analysis and determination of optical properties using EUV spectrometry
  2. Thin-film characterization by EUV spectrometry
  3. Characterization of nanoscale structures by EUV spectrometry and EUV scatterometry

The measurement principle is based on the wavelength-resolved measurement of the reflectance of a sample at different angles of incidence. Successively, the investigated sample parameters are reconstructed in simulative reconstruction procedures which are based on theoretical models of the interaction between radiation and the samples.

Several research topics are addressed in the group:

  • Ongoing development of the experimental setup with respect to improved measurement accuracy and extension of application possibilities
  • Ongoing development of theoretical models, simulation software and fitting algorithms, e.g. with respect to the amount of reconstructable sample parameters, reconstruction accuracy, and the use of advanced methods, e.g. neural networks
  • Research questions inspired by applications e.g. fundamental studies on optical constants of different materials in the EUV range or contamination and degradation studies of optical components

The EUV scatterometer is an extension module for the EUV spectrometer which was developed by the research group. With this module, the full diffraction pattern of structured samples can be measured in addition to the wavelength-resolved reflectance. Sub-tasks of the development of a corresponding measurement and evaluation method are carried out within the framework of bachelor and master theses.

  simulated cross section of the nanograting Copyright: © RWTH TOS simulated cross section of the nanograting