A reflectometer for at wavelength characterization of XUV reflection gratings

In our institute a technology centre for production and characterisation of highly efficient precision gratings is established. Within this project a new eflectometer for at wavelength characterisation of the fabricated blazed gratings has been developed and produced. This new chamber complements our SR based metrology instrumentation, namely the existing reflectometer [1] and the polarimeter ellipsometer chamber for polarisation studies on magnetic or non magnetic samples [2]. The main feature of the new reflectometer is the possibility to incorporate real gratings with dimensions up to 300 x 60 x 60 mm3 into the UHV chamber. The samples are adjustable within six degrees of freedom by a newly developed UHV tripod system, and the reflectivity can be measured between 0 and 90 degrees incidence angle for both s and p polarisation geometry. A variety of detectors will be accessable with a high dynamic range of at least 10 orders of magnitude. The reflectometer is coupled permanently to a new optics beamline [3] on a BESSY II bending magnet operating in the UV, EUV and soft x ray range with the polarisation adjustable to either linear or elliptical. It will be available by the end of 201

Investigation of HF plasma treated soft x ray optical elements

The contamination of optical elements mirrors and grati ngs with carbon still is an issue when using soft x ray synchrotron radiation. With an in house developed HF plasma treatment we are able to decontaminate our optics in situ from carbon very efficiently. The cleaning device, a simple Al antenna, is mounted in situ inside the mirror and grating vacuum chambers. A systematic study of the HF plasma cleaning efficiency was performed acquired with in situ and ex situ methods for monitoring An atomic force microscope AFM and a scanning tunneling microscope STM were used before and after the cleaning process to determine the surface morphology and roughness. Reflectivity angular scans using the reflectometer at the BESSY II Metrology Station [1 3] allowed to estimate the thickness of the remaining C layer after different cleaning steps and thereby helped us to determine the etching rate. Re flection spectra measurements in the range of 200 eV 900 eV show the complete remova l of Carbon from the optics without contaminating it with any other elements due to the plasma tr eatment. The data show that the plasma process improves the reflectivity and reduces the roughness of the surface. In addition to that, the region of the optical su rface where the carbon has been removed becomes passivate