Optical constants of beryllium thin layers determined from Mo Be multilayers in spectral range 90 to 134 eV

Mo Be multilayers are promising optical elements for extreme ultraviolet EUV lithography and space optics. Experimentally derived optical constants are necessary for accurate and reliable design of beryllium containing optical coatings. We report optical constants of beryllium derived from synchrotron radiation based reflectivity data of Mo Be multilayers. Results are in good agreement with available data in the literature obtained from the well known absorption measurements of beryllium thin films or foils. We demonstrate synchrotron based at wavelength reflectometry as an accurate and non destructive technique for deriving EUV optical constants for materials that are difficult or unstable to make thin foils for absorption measurement

Highly reflective Ru Y multilayer mirrors for the spectral range of 9 11 nm

The results of the investigation of the reflective characteristics of multilayer mirrors based on Ru Y are presented. Reflection coefficients at the level of 38.5 at an operating wavelength of 9.4 nm. It is shown that the deposition of B4C barrier layers onto Y layers makes it possible to significantly increase the reflection coefficient compared to structures without barrier layers. A reflectance of 54 was obtained for mirrors optimized for 11.4 nm, which is close to the theoretical limit for these material

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

Corrigendum to Single walled carbon nanotube membranes for optical applications in the extreme ultraviolet rang

In this paper, we explore the possibility of using free standing thin films from single walled carbon nanotube SWCNT material in optics of the extreme ultraviolet EUV range. Test samples were fabricated using an aerosol chemical vapor deposition method. Synchrotron radiation was used to record the transmittance spectra of samples in the EUV range. The measured transmittance for a film 40 amp; 8239;nm thick almost monotonously increases from 76 at a wavelength of 20 amp; 8239;nm 99 at a wavelength of 1 amp; 8239;nm. The measured stress strain curve for the test samples shows that the SWCNT based thin films have rather high ductility as opposite to fragile films made of conventional solid state materials. We use numerical simulations to demonstrate that the film strain occurs mainly by straightening and sliding of the nanotubes past each other without forming of strain localization responsible for fragile behavior. The combination of high radiation transmittance and unique mechanical properties makes the SWCNT based thin films very promising for use in the EUV optics. In particular, such films can be used to protect delicate optical elements for EUV lithography from their contamination with debris particle

Influence of Thermal Annealing on the Properties of Multilayer Mo Be Mirrors

he influence of thermal action on X ray optics performance and structure of films and transition regions in multilayer Mo Be mirrors optimized for a reflection maximum in the interval 11.2 11.4 nm at normal incidence has been considered. The annealing temperature reached 300 C and the annealing time was 1 and 4 h. It has been shown that after thermal annealing in vacuum for 1 h at 300 C, the reflection coefficient rises; however, when the annealing time grows to 4 h, it drops. Grains in molybdenum films become finer, and the profiles of transition regions change from exponential to linear. The period of multilayer mirrors has remained the same under all annealing condition

Reflectivity and photoelectron yield from copper in accelerators

For the design of high performance particle accelerators and vacuum systems for high energy colliders, the choice of materials and of their surface treatment is an essential prerequisite. Physical and optical properties of such materials and their coatings are input parameters for programs to simulate their performance and to validate machine design. Materials behavior after exposure to synchrotron radiation SR , produced by the circulating particles, need to be studied because of its detrimental consequences, such as photo induced desorption, heat load, vacuum and beam induced instabilities. Reflectivity, its angular distribution and photo yield, i.e., the number of photoelectrons produced per incident photon, are essential ingredients to simulation codes. Such parameters must be studied not only on materials as they are in accelerators, but also in conditions as close as possible to the operative ones. In this work, we present results of such an experimental campaign, carried out at the Optics Beamline of BESSY II. This experimental setup, designed to investigate quasiperfect x ray optical elements by at wavelength metrology from 35 eV to 1850 eV , is also an ideal tool to perform reflectivity and photo yield studies of vacuum chamber materials. As will be discussed, different roughness and various nano , micro or macro modifications of a Cu surface significantly influence the parameters under study. Energy and angle integrated values for the total reflectivity and photo yield are derived. Such integrated values are representative for material behavior under white light irradiation for the various accelerators discussed her