In situ performance tests of soft-x-ray multilayer mirrors exposed to synchrotron radiation from a bending magnet

Ionic liquid mediated deposition of ruthenium mirrors on glass under multiphase conditions

Stable mirrors of Ru nanoparticles are deposited on borosilicate glass by an ionic liquid and a metal coordinating agent.

Design of multilayer extreme-ultraviolet mirrors for enhanced reflectivity

We show numerically that the reflectivity of multilayer extreme-UV (EUV) mirrors tuned for the 11-14-nm spectral region, for which the two-component, Mo/Be and Mo/Si multilayer systems with constant layer thickness are commonly used, can be enhanced significantly when we incorporate additional materials within the stack. The reflectivity performance of the quarter-wavelength multilayers can be enhanced further by global optimization procedures with which the layer thicknesses are varied for optimum performance. By incorporating additional materials of differing complex refractive indices-e.g., Rh, Ru, Sr, Pd, and RbCl-in various regions of the stack, we observed peak reflectivity enhancements of as much as ~5% for a single reflector compared with standard unoptimized stacks. We show that, in an EUV optical system with nine near-normal-incidence mirror surfaces, the optical throughput may be increased by a factor as great as 2. We also show that protective capping layers, in addition to protecting the mirrors from environmental attack, may serve to improve the reflectivity characteristics.

Thermal stability of sputtered Mo/X and W/X (X = BN:O, B(4)C:O, Si, and C) multilayer soft-x-ray mirrors

We prepared eight samples of Mo/X and W/X (X = BN:O, B(4)C:O, Si, and C) multilayers by magnetron sputtering. Analyses of x-ray photoelectron spectroscopy for the boron nitride and the B(4)C layers showed the concentration of O to be nonnegligible. We have evaluated the thermal stability by measuring soft-x-ray specular reflectances before and after thermal annealing occurs at temperatures as high as 700 °C. The results suggest that the thermal stability depends largely on the inclusion of low-density materials and not on the type of metal. Of the four low-density materials studied, BN:O is thermally the most stable, and the Mo/BN:O multilayer, the most stable among the eight samples, shows stability as high as 700 °C.

Radiation hardness of molybdenum silicon multilayers designed for use in a soft-x-ray projection lithography system

A molybdenum silicon multilayer is irradiated with 13.4-nm radiation to investigate changes in multilayer performance under simulated soft-x-ray projection lithography (SXPL) conditions. The wiggler-undulator at the Berlin electron storage ring BESSY is used as a quasi-monochromatic source of calculable spectral radiant intensity and is configured to simulate an incident SXPL x-ray spectrum. The test multilayer receives a radiant exposure of 240 J/mm(2) in an exposure lasting 8.9 h. The corresponding average incident power density is 7.5 mW/mm(2). The absorbed dose of 7.8 × 10(10) J/kg (7.8 × 10(12) rad) is equivalent to 1.2 times the dose that would be absorbed by a multilayer coating on the first imaging optic in a hypothetical SXPL system during 1 year of operation. Surface temperature increases do not exceed 2 °C during the exposure. Normal-incidence reflectance measurements at λ(0) = 13.4 nm performed before radiation exposure are in agreement with measurements performed after the exposure, indicating that no sign icant damage had occurred.