A micromirror array is a constituent part of an illumination-optical component of a projection exposure apparatus for projection lithography. A multiplicity of micromirrors are in groups in a plurality of mirror modules, each of which has a rectangular module border. The mirror modules are in module columns. At least some of the module columns are displaced with respect to one another along a column boundary line so that at least some of the mirror modules adjacent to one another over the boundary line are arranged displaced with respect to one another. Their module border sides running transversely to the boundary line are not aligned flush with one another. This micromirror array can have a relatively standardized production and can have a relatively small reflection folding angle on the object if the micromirror array represents a final illumination-optical component upstream of a reflective object to be illuminated.

An extreme ultra violet (EUV) light source apparatus includes a metal droplet generator, a collector mirror, an excitation laser inlet port for receiving an excitation laser, a first mirror configured to reflect the excitation laser that passes through a zone of excitation, and a second mirror configured to reflect the excitation laser reflected by the first mirror.

A radiation source apparatus includes a vessel, a laser source, a collector, and a reflective mirror. The vessel has an exit aperture. The laser source is at one end of the vessel and configured to excite a target material to form a plasma. The collector is disposed in the vessel and configured to collect a radiation emitted by the plasma and to direct the collected radiation to the exit aperture of the vessel. The reflective mirror is in the vessel and configured to reflect the laser beam toward an edge of the vessel.

A method for in situ protection of a surface (7a) of an aluminum layer (7) of a VUV radiation reflecting coating (6) of an optical element (4), arranged in an interior of an optical arrangement, against the growth of an aluminum oxide layer (8), including carrying out an atomic layer etching process for layer-by-layer removal of the aluminum oxide layer from the surface. The etching process includes a surface modification step and a material detachment step. At least one boron halide is supplied as a surface modifying reactant to the interior in pulsed fashion during the surface modification step. A plasma is generated at a surface (8a) of the aluminum oxide layer, at least during the material detachment step. The atomic layer etching process is performed until the aluminum oxide layer reaches a given thickness (D), or the aluminum oxide layer is kept below that thickness (D) by the process.

Reflective optical element with extended service life for VUV wavelengths includes a substrate (41) and a metal layer (49) thereon. At least one metal fluoride layer (43) on the metal layer faces away from the substrate and at least one oxide layer (45) on the metal fluoride layer faces away from the substrate. The thicknesses of the layers on the metal layer facing away from the substrate are selected so that the electrical field of a standing wave, formed when a relevant wavelength is reflected, has a minimum in the region of the oxide layer. In addition, the relevant wavelength is selected so that, from a minimum VUV wavelength range to the relevant wavelengths, the integral over the extinction coefficients of the material of the at least one oxide layer is between 15% and 47% of the corresponding integral from the minimum wavelengths to a maximum wavelength.

A method of making a mirror for use with extreme ultraviolet (EUV) or X-ray radiation is disclosed. The method includes: a) providing an optical element having a curved mirror surface, wherein the curved mirror surface comprises localized defects that degrade performance of the curved mirror surface; b) spin-coating the curved mirror surface with a material to cover at least some of the defects; and c) curing the spin-coated material on the curved mirror surface to reduce the number of defects and improve the performance of the curved mirror surface. Also disclosed is a mirror made by the method.

An optical system comprises at least one mirror having a mirror body and a mirror surface, and at least one actuator device coupled to the mirror body and serving for deforming the mirror surface. The actuator device comprises at least one electrostrictive actuator element for generating a mechanical stress in the mirror body for deforming the mirror surface depending on an electrical drive voltage, and at least one electrostrictive sensor element for outputting a sensor signal depending on a deformation of the sensor element. The at least one sensor element is arranged directly adjacent to the actuator element and/or is arranged in such a way that it is configured at least partly for transferring the mechanical stress generated by the actuator element to the mirror body.

An optical assembly of a projection exposure apparatus for semiconductor lithography comprises an optical element and an actuator for deforming the optical element. The actuator is subjected to a bias voltage by a controller that is present. A projection exposure apparatus for semiconductor lithography comprises an optical assembly. A method for operating an actuator for deforming an optical element for semiconductor lithography comprises subjecting the actuator to a bias voltage by a controller.

An EUV collector mirror for an extreme ultra violet (EUV) radiation source apparatus includes an EUV collector mirror body on which a reflective layer as a reflective surface is disposed, a heater attached to or embedded in the EUV collector mirror body and a drain structure to drain melted metal from the reflective surface of the EUV collector mirror body to a back side of the EUV collector mirror body.

An optical element includes: a substrate, a reflective coating, applied to the substrate, for reflecting radiation in a first wavelength range (Δλ.sub.1) between 100 nm and 700 nm, preferably between 100 nm and 300 nm, more preferably between 100 nm and 200 nm, and a protective coating applied to the reflective coating. The substrate is formed from a material which is transparent to the radiation in the first wavelength range (Δλ.sub.1). The reflective coating is applied to a rear face of the substrate and is structured to reflect radiation that passes through the substrate to the reflective coating. Also disclosed are an optical arrangement with at least one such optical element and a method of producing such an optical element.