[en] Extreme UV Lithography (EUVL), the high-resolution imaging technique for which 13.5 nm radiation is used, is the most likely candidate technology for the near future generation wafer steppers for IC production. Because of the high absorption of this radiation in all materials, EUVL requires all-reflective optics for which multilayer coatings based on Bragg reflection are to be used. Traditionally, research on this type of coatings focuses on growth mechanisms, reduction of interface roughness and layer thickness control. In the industrial type of application as EUVL however, considerably more issues play an important role. Firstly, the high reflectance must be obtained over the entire area of the optics for one specific wavelength, which means that the period of the coating should be controlled to be uniform over the substrate or to have a lateral gradient to match the optical design. Secondly, all individual mirrors should reflect at the same wavelength, each for their specific angle of incidence. This requires a high level of process control. An equally important issue for an industrial system is the lifetime of the mirrors under high doses of EUV exposure: reflectivity drops of several percent have been observed within one day. This requires the development of special protective capping layers. Furthermore, the imaging quality of the optics might be reduced due to stress in the coatings which gives rise to deformation of the optical elements. FOM carries out an extensive research programme involving all issues mentioned. The goal is to further enhance the reflectance of the coatings, and to solve the lifetime and imaging issues described above. An overview of the coating related critical topics in EUV Lithography will be presented, including results on a successful protective capping layer that reduces the reflectance loss under EUV exposure significantly. Examples of links between microscopic effects such as crystallization, and macroscopic effects, such as stress, will be given. (Author)