Abstract: A wavefront measuring device and method obtain wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.

Abstract: A wavefront measuring device and method obtain wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.

Abstract: There is provided a wavefront measuring method for obtaining wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.

Abstract: There is provided a wavefront measuring method for obtaining wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.

Abstract: Apparatus and methods are disclosed for milling selected regions on the surface of a multilayer-film reflective surface of an X-ray mirror to correct the reflected wavefront produced by the mirror, thereby producing a more uniform or otherwise more desirable phase distribution of the reflected wavefront. The milled multilayer films include multiple lamina sets each including respective layers of at least two respective substances. The layers usually are “stacked” alternatingly at a fixed period length on a mirror substrate. By selectively removing one or more surficial layers in selected locations, local corrections of the phase shift of the reflective wavefront are achieved. At each milling location, the depth profile can be stepwise or smoothly gradated. Milling methods can include lapping, ion-beam bombardment, plasma-enhanced chemical vapor machining (CVM), reactive-ion etching, photochemical reactions, or laser ablation.

Abstract: Methods are disclosed for correcting the wave aberrations of light reflected from multilayer-film mirrors as used in, e.g., optical systems as used for EUV lithography (EUVL) apparatus. Wave aberrations are corrected by addition and/or removal of one or more layers (typically layer-sets) to and from, respectively, the surface of the multilayer film of the mirror. In certain embodiments, layer-removal is monitored in situ by any of several techniques. In other embodiments, mirror substrates are processed to a prescribed shape precision and surface roughness, followed by formation of the multilayer film and assembly of the mirrors into the intended optical assembly. The wave aberration is measured at operating wavelength. If the measured wave aberration is not within specifications, then the mirrors are corrected individually by selective removal and/or addition of layer-set(s). The corrected mirrors are reassembled and re-tested as an optical assembly. This cycle is repeated as required.

Abstract: Apparatus and methods are disclosed for milling selected regions on the surface of a multilayer-film reflective surface of an X-ray mirror with high accuracy and precision. The milling operation is performed to correct the reflected wavefront produced by the mirror, thereby producing a more uniform or otherwise more desirable phase distribution of the reflected wavefront. The milled multilayer films include multiple lamina sets each comprising respective layers of at least two respective substances. The layers usually are “stacked” in an alternating manner at a fixed period length on a mirror substrate. By selectively removing one or more surficial layers in selected locations, the methods and apparatus disclosed herein provide local corrections of the phase shift of the reflective wavefront. At each milling location on the multilayer-film surface, the depth profile can be stepwise or smoothly gradated.

Abstract: X-ray-generation devices are disclosed that generate X-rays in a stable manner over extended periods of time. An exemplary device includes an anode electrode and a cathode electrode coaxially arranged, and an insulating member. A nozzle connected to a reservoir of fluid target material directs a flow of fluid target material to the anode electrode. Meanwhile, a pulsed high voltage is applied between the anode electrode and cathode electrode in coordination with the supply of target material. The pulses are timed such that, whenever a unit of target material reaches a tip of the anode electrode, a plasma sheath generated at the surface of the insulating member also reaches the tip of the anode electrode. Hence, the target material is supplied automatically as required to produce X-rays continuously over an extended time period. Intense X-ray fluxes can be produced in a stable manner by monitoring the rate at which target material is supplied to the plasma, relative to the timing of discharge pulses.