Extensive optimization on the fabrication of Mo/Si multilayer systems is canied out at the FOM InstituteRijnhuizen using e-beam evaporation. The process is being optimized including parameters such as variation of the mirror's centre wavelength, the metal fraction, deposition parameters, and the layer composition. Reflectivities of 69.5 % are demonstrated at normal incidence, with values of 67 to 69% being routinely achieved, demonstrating the capabilities of the deposition process. Some evidence of smoothening to interface roughness values lower than the roughness of the initial substrate is given. Furthermore, investigation of the temporal behaviour of the coatings does not indicate any loss of reflectivity over an eight-month period. An analysis of the multilayer composition and the interface roughness is given. The reflectivity measurements have been carried out at the PTB facilities at the electron storage rings BESSY I and BESSY II in Berlin. The results of measurements at both facilities are found to be identical and accuracy is discussed in detail.

We developed and demonstrate an analysis method in which we calibrate the intensity scale of cross-sectional transmission electron microscopy ͑TEM͒ using Cu K ␣ reflectometry. This results in quantitative in-depth density profiles of multilayer structures. Only three free parameters are needed to obtain the calibrated profiles, corresponding to three TEM image intensity levels. Additionally, the optical indices of the two multilayer materials used and the assumption that the layers are laterally homogeneous are used in the model. The power and the general usefulness of the method is demonstrated using experimental data of W / Si and Mo/ Si multilayer systems with sharp interfaces as well as multilayers of which the interfaces were deliberately intermixed.

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High performance reflective coatings for EUVL projection systems can be produced by using e-beam evaporation in combination with ion beam smoothening of the interfaces. Using this technique, we recently demonstrated a near normal incidence reflectivity of 69.5%1 Another, equally important part of the optimization of the coating process is the lateral control of the thickness of the layers, that is the d-spacing of the coating. In this paper we demonstrate the ability to obtain a uniformity of the d-spacing of the coating of better than over a 6" area, both on flat and concave surfaces (uniformity specified in terms of wavelength of maximum reflectance). All reflectance measurements have been carried out at the PTB facilities at the electron storage rings BESSY I and BESSY II in Berlin2.

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