MESA+ University of Twente
Industrial focus group XUV Optics


Post Doc Position – Science and Technology


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 in a state of the art thin film laboratory within the MESA+ Institute for Nanotechnology (Enschede), and at Extreme UV beam lines at the lithography equipment manufacturer ASML (Veldhoven).

Job specification

Ultrathin transparent membranes are currently being developed as pellicles for protection of sensitive reticle surfaces in EUV projection lithography. Development of such membranes is challenged by the requirements imposed on them from the application, requiring membrane stability under high intensity EUV illumination. The membranes should be sufficiently thin to allow high transmission of EUV light, but still strong enough to prevent sagging and other mechanical deformations. The lifetime of such membranes is intrinsically linked to the effects of thermal loading under EUV illumination in a chemically active environment, and the mechanical strength of the membrane.

The work involves development of membrane structures that combine high mechanical strength with low absorption of EUV light. Such membranes are envisioned to consist of multiple layers that should address specific requirements, e.g. one or more layers to provide mechanical strength, combined with one or more layers that target heat dissipation and chemical inertness.

For heat dissipation, suspended ultrathin-film membranes present some very unusual physics. Metallic films exhibit enhanced thermal emissivity for thicknesses below the skin-depth, while dielectrics have reduced thermal emissivity under the same conditions. On the other hand, once the film thickness is close to the electron de Broglie wavelength, quantum confinement may begin to play a role. To enhance emissivity and thereby heat dissipation will require understanding and optimization of thin growth conditions together with modelling of their emissivity.

One of the methods to enhance the mechanical strength of a membrane is to develop free-standing membranes from networks of e.g. carbon atoms using self-assembly techniques. This will require understanding of the chemical mechanisms of self-assembly as well as how the choice of functionalization, and choice of substrate influence the mechanical and thermal properties of free-standing membranes.

Your profile

We are looking for a Postdoc who is a skilled experimentalist with PhD degree in physics, materials science, physical chemistry or engineering. Experience with deposition of thin films and their analysis is considered advantageous. Our favored candidates are creative and like to push boundaries. We expect the candidate to have excellent command of the English language as well as professional communication and presentation skills.

For further information you can contact Prof. Fred Bijkerk at, +31 620573555, +31-53-4894885/2130.

Candidates are invited to upload their application at the UT web address, including a short motivation letter, references, and CV to the application button below.