Advanced application of XUV optics (AXO)

Research programme

The AXO group is involved in research and development of XUV- and soft X-ray single- and multilayer systems and optics for new applications in science and technology. The AXO programme also addresses the physics research on these applications. The focus is currently on EUV lithography including the execution of the more applied and technological parts of the FOM XMO programme. For example, the group investigates multilayer growth as a function of layer roughness, and the influence of roughness on reflectivity. It has been found that the roughness can be dramatically reduced by adjusting the layer deposition process. This finding may have a large impact on the fabrication of optics substrates, so far a costly process requiring the utmost of optics polishing techniques.

Other examples of research activities include the development of Scanning Tunneling Microscopy as an in-vacuum analysis technique, integrated with the UHV deposition set-up, and adding up to the already unique instrumentation available at the nSI department.

The group has also fabricated real EUV demonstration optics, which are now built into two ASML-Zeiss prototype scanners in operation for EUVL development at IMEC, Belgium, and the University of Albany, New York.

Another example of EUVL imposing new research requests is found in the ISitCLEAR project (In situ monitoring of contamination layers on EUV optics at Angstrom resolution). The project aims at development of new surface sensitive methods to probe ultrathin contamination layers on multilayer systems: none of the currently available methods meets the extreme sensitivity requirements imposed by lithography.

As a parallel activity, explorative research is being carried out to investigate if multilayer optics can be used for beam line optics of the X-ray Free Electron Laser XFEL that will be build in Hamburg, Germany. Exposures of single- and multilayers to very high intensities EUV and soft X-ray radiation at the prototype X-ray free electron laser FLASH, also in Hamburg, are used to study the potential damage mechanisms and possible effects on the multilayer reflectance. Futhermore, multilayers are being developed for optical elements to be used in experiments at this type of facilities.

More specific and recent information can be found in the annual report 2008.

Fig. 1 Sample loading in one of the three advanced ultra high vacuum multilayer deposition facilities in the nSI department.

Personell