Abstract: High-brightness short-wavelength radiation source contains a vacuum chamber with a rotating target assembly having an annular groove, an energy beam focused on the target, a useful short-wavelength radiation beam coming out of the interaction zone, wherein the target is a layer of molten metal formed by a centrifugal force on a surface of the annular groove facing a rotation axis. A replaceable membrane made of carbon nanotubes may be installed on a pathway of the short-wavelength radiation beam for debris mitigation. In the embodiments of the invention the energy beam is a pulsed laser beam. The pulsed laser beam may consist of pre-pulse and main-pulse, with parameters such as laser pulse repetition rate chosen in order to suppress debris. In other embodiments the energy beam is the electron beam produced by an electron gun and the rotating target assembly is a rotating anode.

Abstract: High-brightness LPP source and method for generating short-wavelength radiation which include a vacuum chamber (1) with an input window (6) for a laser beam (7) focused into the interaction zone (5), an output window (8) for the exit of the short-wavelength radiation beam (9); the rotating target assembly (3), having an annular groove (11); the target (4) as a layer of a molten metal formed by centrifugal force on the surface of the distal wall (13) of the annular groove (11) while the proximal wall (14) of the annular groove is designed to provide a line of sight between the interaction zone and both the input and output windows particularly during laser pulses. A method for mitigating debris particles comprises using an target orbital velocity high enough for the droplet fractions of the debris particles exiting the rotating target assembly not to be directed towards the input and output windows.

Abstract: The invention provides a method and apparatus for a commercially viable EUV light source for EUV metrology and actinic inspection of EUV lithography masks. The invention is carried out using a laser target in the form of a continuous jet of liquid Lithium, circulated in a closed loop system by means of a high temperature pump. The collector mirror is placed outside the vacuum chamber in an environment filled with an inert gas and EUV output to a collector mirror is provided through the spectral purity filter, configured as an EUV exit window for the vacuum chamber. In the vacuum chamber, the input window for the laser beam is coated with a screening optical element. Evaporative cleaning of the EUV spectral purity filter and the screening optical element is provided. The protective shield with a temperature higher than 180° C. may be adjusted around the target jet.