Control Of Lateral Thickness Gradients Of Euv/Soft X-Ray Multilayer On Curved Substrates

To meet the requirements of wavelength matching and figure preservation for EUV multilayer optics, study of precise control of the lateral thickness gradients of multilayer was performed. The distribution of the magnetron sputtering source was derived by fitting the coating thickness profiles of flat substrates sweeping across the source with constant velocity at different heights using genetic algorithm. Then, genetic algorithm was also used in finding the proper speed profiles for the desired thickness profiles. By the method mentioned above, extremely precise control of the lateral thickness gradients of multilayer on curved substrates was realized.