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Development of EUV radiometry

Cooperation project with Carl Zeiss SMT GmbH continued

PTB-News 1.2017
Especially interesting for

the semiconductor industry

EUV lithography

optical metrology

The cooperation project with Carl Zeiss SMT GmbH in the field of radiometry, which started back in 1998, has been prolonged until the end of 2020. At PTB, this cooperation project represents the starting point and the basis of a field of work which provides extensive metrological support to the German and the European semiconductor industry for the development of EUV lithography. Besides EUV reflectometry and EUV detector radiometry, the metrological developments are especially geared to EUV scatterometry in a group of cooperation partners which has considerably grown over the past few years.

PTB's EUV beamline at the Metrology Light Source. In the foreground (right), one can see the clean-room in which the samples are assembled. The large-scale EUV reflectometer is located at the back of it (concealed). The mirrors, some of which are very large and heavy, are mounted into the reflectometer by a robot (seen on the left in the cleanroom).

EUV lithography is an optical technology at a working wavelength of 13.5 nm, by means of which it will be possible to realize high-end semiconductor components in the near future. The driving forces of this technological development are the world leader on the lithography stepper market, ASML from the Netherlands, and its German partner for precision optics, Carl Zeiss SMT GmbH. PTB has maintained cooperation agreements on EUV radiometry with both companies for several years. Meanwhile, cooperation projects are being realized with basically all renowned representatives of the German and European supply industry in order to develop EUV lithography.

Besides the number of hours now amounting to more than 6000 per year, also the qualitative requirements placed on the measurements in EUV radiometry, which is performed in several shifts with synchrotron radiation at two beamlines at the electron storage rings BESSY II and Metrology Light Source (MLS) in BerlinAdlershof, are increasing. This is the reason why the original large-scale EUV reflectometer – which had been set up together with Carl Zeiss within the scope of a BMWi-funded project in the first years of the cooperation project – will, in the coming years, be replaced by a new system equipped with a hydrocarbon-free vacuum system and improved sample positioning. The setup of an EUV telescope system, with the aid of which the spatial resolution on the surface of the optical components shall be improved to approximately 10 µm, in contrast, is close to completion. This benefits especially the development of novel measurement procedures based on EUV reflectometry and scatterometry for the investigation of structured surfaces. Due to the short wavelength used, these procedures could in future complement or even replace optical scatterometry in structure measurements on semiconductor wafers.

Frank Scholze
Department 7.1 Radiometry with Synchrotron Radiation
Phone: +49 (0)30 3481-7120

Scientific publication

V. Soltwisch, A. Haase, J. Wernecke, J. Probst, M. Schoengen, S. Burger, M. Krumrey, F. Scholze: Correlated dif-fuse x-ray scattering from periodically nanostructured surfaces. Phys. Rev. B 94, 035419 (2016)