MESA+ University of Twente
Industrial focus group XUV Optics




Physics and Chemistry of Extreme UV Multilayer Optics

TEM (full stack) cropped

Ultrathin films of nanoscale thickness find a major application in multilayer reflective optics. By tuning the layer thickness, these layered stacks can reflect short-wavelength light from the ultraviolet to the soft X-ray range. When designed for the Extreme UV case, e.g. 13 nanometer, multilayers have enabled the sensational development of a high-resolution lithographic technology for the manufacture of integrated circuits. At the basis of this success was forefront fundamental research by the Foundation FOM and the MESA+ Institute. MESA+ has now started a new multidisciplinary research programme to study the thin film physics and chemistry of such optics. The research will take place in a brand new thin film laboratory within the MESA+ Institute for Nanotechnology (Enschede), and at Extreme UV beam lines at the lithography equipment manufacturer ASML (Veldhoven).

Research field. The interaction of high-intensity ion and photon beams with thin film surfaces is a fascinating process. It involves both ion- and photon-induced physical reactions as well as photo- and plasma chemistry at the surfaces. Essential is also the control of layer growth down to sub-nanometer precision. The experimental approach will be to isolate the individual processes and to understand and control them at the atomic and molecular level, with support of analytical methods and thin film growth set-ups. The scientific programmes at MESA+ and ASML include world-leading research activities in each of these areas, exploiting high flux photon sources and ion beam generators, equipment to study surface photochemistry from the infrared to the extreme UV, atomic-scale layer growth set-ups and surface analysis facilities, state-of-the-art (particle) inspection and diagnostics and a range of numerical tools. The research is done in close collaboration with other industrial and academic parties, including Carl Zeiss SMT, ASML, PANalytical, DEMCON, SolMateS, TNO, and various research institutes.

The available positions concern:

- Ultra high intensity ultra short exposure of multilayer systems to explore lifetime issues such as layer intermixing, EUV-induced photo-dissociation, or other detrimental effects. These femtosecond irradiation experiments are scheduled at specialized external set-ups (base location UT).

- Energy dependent surface photochemistry involving the specific photochemistry of e.g. physisorbed hydrocarbons or water at different photon energies under vacuum conditions, including direct photo-induced processes (location ASML).

- Layer interface interactions in multilayer mirrors, with the aim to identify and control interface processes in ultrathin compounded systems for wavelengths down to a few nanometers. Such multilayer systems are used as spectroscopic elements for x-ray materials analysis (location UT).

- The design and construction of a short-wavelength light source and beam line for the analysis of future multilayer mirrors. The light source consists of a high density, laser-, or electrically generated plasma (location UT).

- Tailoring the optical response of EUV optics by changing the optical as well as the thin film composition, including anti-reflectance coatings, diffractive filtering systems, and multilayers with new optical properties (location UT).

- The design and fabrication of adaptive EUV optics, consisting of layered structures of which the optical properties can be adjusted by an electrical or thermal signal (location UT).

Qualifications. Applicants should have, or pursue, a Master degree in Experimental or Technical Physics, Chemistry, or Photonics, or an equivalent diploma giving access to doctoral studies. Experience in either surface photochemistry, plasma physics, plasma/ion surface interactions, thin film physics, material science, optics or spectroscopy is an advantage.

Employment Conditions. The University of Twente offers a stimulating work environment in an area of applied, forefront research. When fulfilling a PhD position at the UT, you will get the status of junior scientist. You will have an employment contract for the duration of 4 years and can participate in all employee benefits the UT offers. The gross monthly salary starts with € 2083,- in the first year and increases to € 2664,- in the fourth year of your employment. The salary is supplemented with a holiday allowance of 8% and an end-of year bonus of 8.33%.
When applying for a trainee position, special arrangements apply, with partial coverage of expenses. A high-quality training programme is part of the agreement. You and your supervisor will make up a plan for the additional education and supervising that you specifically need. The research has to result in a thesis at the end of the employment period. Depending on the topic, the positions are based at Veldhoven or Enschede; they are available immediately.

Information. Employment conditions are laid down in the ‘CAO onderzoek­instellingen’ and can be consulted at the UT website. General information on working at the UT can also be found there. For further information please contact Prof.dr. Fred Bijkerk +31 534896170 or Dr. Eric Louis on +31 534894378, or mail to or

Application. Your letter of application with resume, papers, and references can be submitted to the UT website.