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Resume. Le developpement de miroirs EUV resistant a des temperatures elevees represente un enjeu important pour la lithographie EUV. Nous avons optimise et depose plusieurs empilements multicouches Mo/SiC/Si/SiC en faisant varier les epaisseurs respectives de SiC aux deux interfaces. Ces differents types d’empilements ont ensuite subi une serie de recuits thermiques pour evaluer l’influence des deux parametres temps et temperature de recuit, sur les performances spectrales. Des structures stables apres un recuit de 200 h a 400 ◦C ont ete optimisees et caracterisees.

Through its participation to European programs, SAGEM has worked on the design and manufacturing of normal incidence collectors for EUV sources. By opposition to grazing incidence, normal incidence collectors are expected to collect more light with a simpler and cheaper design. Designs are presented for the two current types of existing sources: Discharge Produced Plasma (DPP) and Laser Produced Plasma (LPP). Collection efficiency is calculated in both cases. It is shown that these collectors can achieve about 10 % efficiency for DPP sources and 40 % for LPP sources. SAGEM works on the collectors manufacturability are also presented, including polishing, coating and cooling. The feasibility of polishing has been demonstrated with a roughness better than 2 angstroms obtained on several materials (glass, silicon, Silicon Carbide, metals...). SAGEM is currently working with the Institut d'Optique and the Laboratoire des Materiaux Avances on the design and the process of EUV coatings for large mirrors. Lastly, SAGEM has studied the design and feasibility of an efficient thermal control, based on a liquid cooling through slim channels machined close to the optical surface.

The development of new high power EUV sources and EUV space imaging requires optics having specific properties which depend on applications and operating conditions. These both applications are very different in the working multilayers environment. For the high power sources, multilayers are submitted to short pulses with high energy peak whereas, for the space imaging, multilayers are submitted to continuous flux with low level. Moreover photon energy and environment for both applications may be different. The environment may affect structure and top layer contamination when optics are stored, handled, mounted on the final device and finally operating. Main environmental parameters investigated are temperature and humidity variation. One objective is the optimisation of multilayer coatings to offer the highest resistance under photonic, ionic fluxes and temperature cycle. This means that interfacial diffusion between thin layers and degradation of the capping layers have to be avoided or reduced. The present study relies with designing, depositing and testing different structures of multilayer coatings in order to minimise the influence of the environment. Multilayer coatings based on molybdenum, silicon and silicon carbide materials have been deposited by magnetron sputtering on silicon and zerodur substrates. Samples were submitted to radiations emitted by an EUV source at wavelength closed to 13.5 nm. Furthermore they were also submitted to thermal cycles and annealing under warm humidity in the aim to simulate extremes storage or handling conditions as space mission's conditions. The damages and the performance of the multilayers were evaluated by using grazing incidence reflectometry at 0.154 nm and EUV reflectometry at the operating wavelength. After a presentation of the multilayer design, deposition and metrology tools, we will describe the different environmental effects on the coatings to take in care during EUV source exposure, handling and storage conditions. First results on multilayers performances to EUV source exposure and space specification tests are presented. Main damages studies were on annealing, thermal cycling and warm humidity.

In 1994, REOSC took the decision to set up a large optics Ion figuring facility to be operational within 18 months. The equipment was designed to be able to accept components up to the maximum dimensions of 1.3 X 1.3 X 1.3 meters mounted in a high-vacuum chamber. After a period of design, fabrication, installation and validation, the Ion Beam Facility came is now, since more than two years, fully integrated in our production line as an efficient complementary technique to the mechanical polishing. We present in this paper some experimental results showing the maturity of the technology as well as some recent improvements and future applications.

For a long time, the use of very large mirror was devoted to astronomy observations. Due to the dimensions, the coating of such mirrors was a difficult challenge, but the precision on the value of the reflectance and the uniformity of the coating thickness were not very critical. Now, such mirrors are designed for other applications and their specifications are at the moment very hard to achieve.