An imaging optical unit for EUV projection lithography serves to image an object field into an image field. Mirrors guide imaging light from the object field to the image field. An aperture stop is tilted by at least 1 in relation to a normal plane which is perpendicular to an optical axis. The aperture stop has a circular stop contour. In mutually perpendicular planes, a deviation of a numerical aperture NA.sub.x measured in one plane from a numerical aperture NA.sub.y measured in the other plane is less than 0.003, averaged over the field points of the image field. What emerges is an imaging optical unit, in which homogenization of an image-side numerical aperture is ensured so that an unchanging high structure resolution in the image plane is made possible, independently of an orientation of a plane of incidence of the imaging light in the image field.

A method and system for fracturing or mask data preparation or optical proximity correction or proximity effect correction or mask process correction is disclosed in which a set of shaped beam shots is determined that is capable of forming a pattern on a surface, where the set of shots provides different dosages to different parts of the pattern, and where the dose margin from the set of shots is calculated. A method for forming patterns on a surface is also disclosed.

A method for characterizing a lithography apparatus, in particular, a method for characterizing a lithography apparatus configured to cause an obscuration of radiation, as well as a lithography apparatus and a computer program product configured to carry out the methods. A method for characterizing a lithography apparatus; detecting first diffracted radiation of the lithography apparatus, wherein the first diffracted radiation was diffracted at a characterization element; determining a diffraction property of the characterization element based on at least in part the first substantially undiffracted radiation and the first diffracted radiation.

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.

There is provided a reflective imaging optical system forming an image of a first plane onto a second plane, wherein the numerical aperture with respect to a first direction on the second plane is greater than 1.1 times a numerical aperture with respect to a second direction crossing the first direction on the second plane. The reflecting imaging optical system has an aperture stop defining the numerical aperture on the side of the second plane, and the aperture stop has an elliptic-shaped opening of which size in a major axis direction is greater than 1.1 times that in a minor axis direction. The reflective image-forming optical system is applicable to an exposure apparatus using, for example, EUV light and capable of increasing numerical aperture while enabling optical path separation of light fluxes.

A method and system for fracturing or mask data preparation or optical proximity correction or proximity effect correction or mask process correction is disclosed in which a set of shaped beam shots is determined that is capable of forming a pattern on a surface, where the set of shots provides different dosages to different parts of the pattern, and where the dose margin from the set of shots is calculated. A method for forming patterns on a surface is also disclosed.

An imaging optical unit for EUV projection lithography serves to image an object field into an image field. Mirrors guide imaging light from the object field to the image field. An aperture stop is tilted by at least 1 in relation to a normal plane which is perpendicular to an optical axis. The aperture stop has a circular stop contour. In mutually perpendicular planes, a deviation of a numerical aperture NA.sub.x measured in one plane from a numerical aperture NA.sub.y measured in the other plane is less than 0.003, averaged over the field points of the image field. What emerges is an imaging optical unit, in which homogenization of an image-side numerical aperture is ensured so that an unchanging high structure resolution in the image plane is made possible, independently of an orientation of a plane of incidence of the imaging light in the image field.

A lithographic system including a lithographic apparatus with an anamorphic projection system, and a radiation source configured to generate an EUV radiation emitting plasma at a plasma formation location, the EUV radiation emitting plasma having an elongate form in a plane substantially perpendicular to an optical axis of the radiation source.

There is provided a reflective imaging optical system forming an image of a first plane onto a second plane, wherein the numerical aperture with respect to a first direction on the second plane is greater than 1.1 times a numerical aperture with respect to a second direction crossing the first direction on the second plane. The reflecting imaging optical system has an aperture stop defining the numerical aperture on the side of the second plane, and the aperture stop has an elliptic-shaped opening of which size in a major axis direction is greater than 1.1 times that in a minor axis direction. The reflective image-forming optical system is applicable to an exposure apparatus using, for example, EUV light and capable of increasing numerical aperture while enabling optical path separation of light fluxes.

A lithography method may include placing a patterning device and a substrate in a lithography apparatus, irradiating a first region of the substrate with a diffraction light and increasing an optical path difference (OPD) of the diffraction light on the first region. The diffraction light may include first and second diffraction lights, and the OPD may be a difference in optical path between the first and second diffraction lights. The lithography apparatus may include an illumination source part configured to emit a radiation beam that is used as the diffraction light, a substrate table supporting the substrate, a supporting structure supporting the patterning device and optically connected to the illumination source part, and a projection part optically connected to the supporting structure and configured to irradiate the substrate with the first and second diffraction lights. The illumination source part may include a monopole source.