Lithographic processes are currently being routinely used for the mass production of micro- and nanostructures – especially computer chips. The lithography processes for the generation of microstructures have been continually improved since the 1960’s. However, since further development of the laser technology used today is more or less limited down to the 248 nm wavelength, and since laser technology can not be economically advanced beyond this point, the semi-conductor industry has placed a high priority on developing nanotechnologies.

Plans aim at taking a technological leap in beam sources from 248 nm down to 13.5 nm. This will ensure that smaller and smaller, and more efficient microchips can be produced well into the future.

The Laser Zentrum Hannover e.V. (LZH) is one of the leading institutions in the European Cost-Network, in which aproximately 100 scientists from 40 institutes, universities, and industrial and public research centers from 15 European countries are presently working. Four working groups are concerned with discussing and developing concepts and strategies for innovative beam sources in the EUV and X-ray spectral ranges, and their applications. The Laser Zentrum Hannover e.V. (LZH) is a member in several working groups, and is a representative of Germany in the Management Committee, which is the head of the consortia.

Main areas of work

• Development and application of X-ray sources and sources in the extreme ultraviolet spectral range (EUV)
• Characterisation of optical systems of samples
• EUV and X-ray measurement technology
• Material investigations
• Design and construction of metrology equipment

Within the framework of industrial research and development projects, a reflectometer for the investigation of curved debris samples for grazing incidence of EUV radiation was developed in the nanolithography group. Measurements at grazing incidence are very sensitive to misalignment. For this reason, the automated unit was provided with algorithms for self-analysis, meaning the reflectometer can examine and correct the alignment and operational settings in detail, on a stand-alone basis. Using the algorithms, it can make fine adjustments after being roughly set, and can repeatedly return to optimal adjustment settings, a considerable improvement of long-term repeatability conditions over a long term basis.

A current issue deals with the characterisation of EUV optics for industrial applications. Whereas standard optics can easily and quickly be measured using the EUV reflectometer described above, special measurement fixtures are necessary for non-standard optics. Based on the experience made with a previously built EUV reflectometer for Wolter-Shell-Type-I-collectors, such as used for gas discharge sources, concepts for the characterisation of multilayer coated collectors have also been developed and tested in pre-investigations.

One of the other main areas of research deals with the miniaturisation of measurement units and lithographic set ups, with the goal of making technologies available for daily use in university or industrial research laboratories which, because of their size and costs, are usually only found in larger institutions. In order to achieve this, these systems need to be made more compact and less expensive, while at the same time retaining their original technical specifications. This has already been demonstrated in a study for a mobile EUV metrology system (see illustration). The measurement technology which is usually only found in a synchrotron or a large, permanent system fits into a standard carrying case.