An optical pulse for an extreme ultraviolet (EUV) light source may be formed by illuminating a semiconductor material of a modulation system with a first light beam having a first wavelength; applying a voltage to the semiconductor material for a time duration, the applied voltage being sufficient to modify an index of refraction of the semiconductor material such that a polarization state of a light beam having a second wavelength passing through the semiconductor material is modified to pass through at least one polarization-based optical element of the modulation system; and forming an optical pulse by passing a second light beam having the second wavelength through the semiconductor material during the time duration.

An exposure method and apparatus for illuminating a pattern with an illumination system to expose a substrate through a projection system. The pattern is illuminated with illumination light with a light amount distribution in which an amount of light is larger in a pair of first areas and a pair of second areas than in an area other than the first and second areas on a pupil plane of the illumination system. The pair of the first areas being arranged outside an optical axis, the pair of the second areas being arranged on ten same straight line as the pair of the first areas are arranged on, and the pair of the second areas being arranged outside the pair of the first areas.

An illumination optical system which illuminates an illumination objective surface with a light from a light source. The illumination optical system includes a spatial light modulator which includes a plurality of optical elements arranged within a predetermined plane and controlled individually, and which forms a light intensity distribution in an illumination pupil of the illumination optical system; and a polarization unit which is arranged in a position optically conjugate with the predetermined plane, and which polarizes an incident light beam having a first and second partial light beams, coming into the polarization unit such that the first and second partial light beams have polarization states different from each other, and emits the polarized incident light beam as an outgoing light beam, wherein the polarization unit changes, in a cross section of the outgoing light beam, a ratio between a cross sectional areas of the first and second partial light beams.

An illumination optical apparatus illuminates a pattern on a mask with illumination light. The illumination optical apparatus includes an optical integrator arranged in an optical path of the illumination light, and a polarization member made of optical material with optical rotatory power, which is arranged in the optical path on an incidence side of the optical integrator, and which changes a polarization state of the illumination light. The illumination light from the polarization member is irradiated onto the pattern through a pupil plane of the illumination optical apparatus.

An exposure apparatus includes a polarizing member polarizing illumination light, and a filter having at least one opening. The polarizing member includes a first polarizing unit and a second polarizing unit arranged so as to surround the first polarizing unit. The second polarizing unit is configured so as to polarize the illumination light entering the second polarizing unit in the circumferential direction along the outer circumference of the first polarizing unit. At least a portion of the first polarizing unit is configured to polarize the illumination light in the direction orthogonal to the polarization direction in a part of the second polarizing unit located on the side opposite to the central part of the first polarizing unit. The openings are arranged in the filter so that the illumination light at the post stage of the filter and the polarizing member includes the illumination light polarized by the first and second polarizing units.

Metrology apparatus and methods are disclosed for measuring a structure formed on a substrate. In one arrangement, different components of a radiation beam are selectively extracted after reflection from the structure and independently detected. For each component, radiation is selected from one of a plurality of predetermined regions in a downstream pupil plane of the optical system downstream from the structure. Radiation is further selected from one of two predetermined orthogonal polarization states. The predetermined orthogonal polarization states are oriented differently as a pair for each of at least a subset of components comprising radiation selected from different predetermined regions in the downstream pupil plane.

A cone-based polarizer includes a beam splitter including a front side (FS) and a back side (BS) part for receiving a first and a second beam portion, respectively. The FS part includes two prisms including parallel first and second FS hypotenuses, and the BS part includes two prisms including parallel first and second BS hypotenuses. A first TIR cone is on top and a second TIR cone is on a bottom of the beam splitter. The first and second TIR cones are aligned to have an essentially common cone axis direction and are configured to add a structured polarization upon retroreflecting. The first and second FS hypotenuses have a FS TIR interface in-between and are angled at about 45 degrees relative to the cone axis direction. The first and second BS hypotenuses have a BS TIR interface in-between and are angled at about 90 degrees relative to the FS hypotenuses.

A microlithography optical system includes a projection objective and an illumination system that includes a temperature compensated polarization-modulating optical element. The temperature compensated polarization-modulating optical element includes a first polarization-modulating optical element of optically active material, the first polarization-modulating optical element having a first specific rotation with a sign. The temperature compensated polarization-modulating optical element includes also includes a second polarization-modulating optical element of optically active material, the second polarization-modulating optical element having a second specific rotation with a sign opposite to the sign of the first specific rotation.

There is disclosed a polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, the polarization-modulating element being made of an optical material with optical activity and having a circumferentially varying thickness profile.

The illumination optical system for illuminating an illumination target surface with light from a light source is provided with a polarization converting member which converts a polarization state of incident light to form a pupil intensity distribution in a predetermined polarization state on an illumination pupil of the illumination optical system; and a phase modulating member which is arranged in the optical path on the illumination target surface side with respect to the polarization converting member and which transmits light from the pupil intensity distribution so as to convert linearly polarized light thereof polarized in a first direction, into required elliptically polarized light and maintain a polarization state of linearly polarized light polarized in a second direction (X-direction or Y-direction) obliquely intersecting with the first direction, in order to reduce influence of retardation caused by a subsequent optical system between the polarization converting member and the illumination target surface.