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>

Improved temperature stability of Mo/Si multilayers by carbide based diffusion barriers through implantation of low energy CHx+ ions

“…This technology is aimed to succeed the current optical and deepultraviolet technologies in the process of producing microelectronic circuits [2,3]. High reflectance of the multilayer, comprising more than 60 layer pairs, is crucial because of the strong dependence of the throughput of the optical system on the number of multilayer-coated surfaces [4,5].…”

Thermal evolution of carbon in annealed Co/C soft x-ray multilayers

“…1 Multilayers are useful in many important technological x-ray applications such as microscopy, 2 astronomy, 3 lithography, 4 imaging, 5 spectroscopy, 6 and x-ray lasers. 7 The best material combinations for soft x-ray multilayers found to date are metal/C for ϭ 4.5-6.5 nm, 5,[8][9][10] Ru/B 4 C for ϭ 6.5-12.4 nm 11 and Mo/Si for ϭ 12.4-30 nm.…”

Design approach and comparison of projection cameras for EUV lithography

“…This coating introduces both amplitude and phase effects. [11][12][13][14] In this section we develop a theoretical model based on aberration theory to estimate to second-order multilayer phase changes. We also introduce a simplified model for a multilayer coating that we use in a ray-tracing Fig.…”