title: Multilayer mirror technology for soft-x-ray projection lithography.
abstract: <p>Recent advances in multilayer mirror technology meet many of the stringent demands of soft-x-ray projection lithography (SXPL). The maximum normal-incidence reflectivity achieved to date is 66% for Mo/Si multilayers at a soft-x-ray wavelength of 13.4 am, which is sufficient to satisfy the x-ray throughput requirements of SXPL. These high-performance coatings can be deposited on figured optics with layer thickness control of ˜ 0.5%. Uniform multilayer coatings are required for SXPL imaging optics, for which maintaining the surface figure is critical to achieving diffraction-limited performance.</p> <p>In contrast the coatings on the condenser optics will be graded to accommodate a large range of angles of incidence. Graded multilayer coatings can also be used to modify the figure of optical substrates without increasing the surface roughness. This offers a potential method for precise fabrication of aspheric imaging optics.</p>
authors.forename: D G
authors.initials: DG
authors.lastname: Stearns
authors.forename: R S
authors.initials: RS
authors.lastname: Rosen
authors.forename: S P
authors.initials: SP
authors.lastname: Vernon