An optical element (14) transparent for radiation with a wavelength in the ultraviolet wavelength range below 250 nm, in particular at 193 nm, comprises a substrate (17) with a refractive index n.sub.s larger than 1.6, and an antireflection coating (16) formed on at least part of the surface of the substrate (17) between the substrate (17) and an ambient medium with a refractive index n.sub.A, preferably with n.sub.A=1.0. The antireflection coating (16) consists of a single layer of a material with a refractive index n.sub.L of about n.sub.L={square root over (n.sub.An.sub.S)}, in particular n.sub.L>1.3, and the optical thickness d.sub.L of the single layer is about /4. The optical element (14) is preferably part of a projection objective (5) in a microlithography projection exposure apparatus (1) and located adjacent to a light-sensitive substrate (10).

An optical element for incorporation into a holding device for forming an assembly for constructing an optical system comprises a body transparent to light from a used wavelength range, on which a first light passage surface and an opposing second light passage surface are formed. Each light passage surface has an optical used region for arrangement in a used beam path of the optical system and an edge region outside the optical used region and designated as an engagement region for holding elements of the holding device. Each light passage surface is of optical quality in the optical used region and has a surface shape designed in accordance with a used region specification specified by the function of the optical element in the used beam path. Light deflection structures with a geometrically defined surface design are in the edge region of at least one of the light passage surfaces.

The problem of the presence of excess flare in maskless photolithography systems is addressed by systems and methods that utilize an aerial imaging system to monitor flare associated with the maskless photolithography systems.

A stop, such as a numerical aperture stop, obscuration stop or false-light stop, for a lithography apparatus, includes a light-transmissive aperture and a stop element, in which or at which the aperture is provided. The stop element is opaque and fluid-permeable outside the aperture.

An optical proximity correction method includes loading a target layout for a mask, generating a correction density map based on manipulation of flare to correct global errors caused by exposing equipment, generating a flare map via convolution integration of the correction density map and a point spread function (PSF) regarding the flare, and correcting the target layout using the flare map and an OPC model.

A method for compensating for an exposure error in an exposure process of a lithographic apparatus that comprises a substrate table, the method comprising: obtaining a dose measurement indicative of a dose of IR radiation that reaches substrate level, wherein the dose measurement can be used to calculate an amount of IR radiation absorbed by an object in the lithographic apparatus during an exposure process; and using the dose measurement to control the exposure process so as to compensate for an exposure error associated with the IR radiation absorbed by the object during the exposure process.

A substrate support configured to support a substrate. The substrate support has a plurality of burls protruding from a base surface of the substrate support. The burls have distal ends for supporting a lower surface of the substrate with a gap between the base surface of the substrate support and the lower surface of the substrate. The substrate support has a liquid supply channel configured to supply a conductive liquid to the gap so as to bridge the gap between the base surface of the substrate support and the lower surface of the substrate, to allow charge to pass between the substrate support and the substrate. The substrate support has a controlled electrical potential such that charge distribution at the lower surface of the substrate can be manipulated.

A stage apparatus includes a first movable stage that moves while holding an article, an electrical contact that is provided on the first movable stage, and a grounding device that comes into contact with the electrical contact and grounds the first movable stage when the article is not processed.

A method of determining contamination of an optical sensor of a sensing system in a lithographic apparatus, the method comprising directing EUV radiation through an opening in a reticle masking blade (26) and onto a patterning device, projecting reflected EUV radiation onto the sensing system and thereby causing build-up of an area of contamination, measuring a height of the area of contamination and a height of an area of the sensing system which did not receive the reflected EUV radiation, and using the measured heights to determine an amount of contamination on the optical sensor of the sensing system.

An assembly includes a window useful for optical access to an interior of an extreme ultraviolet (EUV) light source vessel, the window having a transmission band and a protector configured to shield the window from the interior of the EUV light source vessel, the protector comprising a sheet with a surface facing the window across a gap, the sheet having a thermal conductivity in the range of 10 to 2000 W/(m.Math.K). The sheet can be a sapphire sheet, and can have an optical coating on the surface facing the window, the coating reflecting at least some radiation outside the transmission band, and the opposite side of the sheet can be bare sapphire.