SOFT-X-RAY MULTILAYER MIRRORS WITH LATERALLY VARYING FILM THICKNESSESFABRICATED USING LASER-BEAM-SCANNING CHEMICAL-VAPOR-DEPOSITION

The authors have developed a control method of spatial film thickness distribution of multilayer mirrors for soft-x-ray focusing systems usi ng an argon-fluoride (ArF) excimer laser-induced chemical vapor deposi tion (LCVD). A line-shaped laser beam is unidirectionally scanned over an area of 100x100 mm(2). The scanning speed is controlled in respons e to a film thickness distribution which is required to be obtained. A tungsten-silicon (W/Si) multilayer with laterally varying film thickn ess is successfully fabricated on the design rule, and soft-x-ray (lam bda=12.8 nm; not polarized) reflectivities from 37% to 20% are obtaine d at the grazing angles from 18 degrees to 22 degrees in response to t he film thickness distribution. Furthermore, the amount of the soft x rays reflected by the multilayer within 100 mm of the substrate is est imated at about 90% of that in the case of the designed distribution, and the feasibility of LCVD for fabricating multilayer mirrors for hig h performance soft-x-ray focusing systems has been demonstrated. (C) 1 995 American Institute of Physics.