Disclosed is a wavefront sensor for measuring a tilt of a wavefront at an array of locations across a beam of radiation, wherein said wavefront sensor comprises a film, for example of Zirconium, having an indent array comprising an indent at each of said array of locations, such that each indent of the indent array is operable to perform focusing of said radiation. Also disclosed is a radiation source and inspection apparatus comprising such a wavefront sensor.

Disclosed is a projection system for a lithographic apparatus, comprising: a plurality of optical elements configured to direct a beam along a path, and a control system configured to receive an input signal indicative of a deformation of a first optical element of the plurality of optical elements. The plurality of optical elements may be configured to position the beam onto an object arranged on an object support, and a pattern may be imparted on the beam by a patterning device arranged on support structure. The control system is configured to generate an output signal for controlling a position of at least a second optical element of the plurality of optical elements, based on said input signal; and/or an output signal for controlling a position of said object support, based on said input signal; and/or an output signal for controlling a position of said support structure, based on said input signal.

A method for determining a component of optical characteristic of a patterning process. The method includes obtaining (i) a plurality of desired features, (ii) a plurality of simulated features based on the plurality of desired features and an optical characteristic of a patterning apparatus, and (iii) a performance metric (e.g., EPE) related to a desired feature of the plurality of desired features and an associated simulated feature of the plurality of simulated features; determining a set of optical sensitivities of the patterning process by computing a change in value of the performance metric based on a change in value of the optical characteristic; and identifying, based on the set of optical sensitivities, a set of components (e.g., principal components) of the optical characteristic that include dominant contributors in changing the value of the performance metric.

An exposure apparatus that exposes a substrate to light by using an original in which a pattern is formed includes an illumination optical system arranged to guide illumination light to the original, the illumination light including first illumination light with a first wavelength and second illumination light with a second wavelength different from the first wavelength, and a projection optical system arranged to form a pattern image of the original by using the illumination light at a plurality of positions in an optical axis direction. The illumination optical system is configured to adjust a position deviation in a direction perpendicular to the optical axis direction between a pattern image formed by the first illumination light and a pattern image formed by the second illumination light by changing an incident angle of the illumination light entering the original.

An exposing apparatus for exposing a substrate to transfer a pattern formed on an original to the substrate by using exposure light from a light source includes a projecting optical system configured to guide the exposure light having passed through the original to the substrate, a measuring unit configured to measure a position of the substrate in a first direction perpendicular to a substrate surface of the substrate by making measurement light incident on the substrate surface and to receive the measurement light reflected by the substrate surface, and a traveling direction setting means configured to set a traveling direction of first gas so as to supply the first gas toward a first space between the projecting optical system and the substrate from a first gas supplying mechanism, in which the first space is different from a second space through which the measurement light passes.

A projection exposure apparatus includes a light source, an illumination system, and a projection lens. A method for producing or setting the projection exposure apparatus includes determining a first imaging property to be optimized. Optimizing the first imaging property includes optimizing the setting of the illumination system and/or the structure of the mask and/or at least one first adjustable optical element of the projection lens with respect to the shape of one of its at least one optically effective surfaces or with respect to the optical effect for the purposes of setting an optimized wavefront of the working light. Optimizing the illumination system, mask and/or optical element of the projection lens is implemented so that a further manipulator of the projection exposure apparatus for manipulating the wavefront is set in the central position of its manipulation range during the optimization of the first imaging property.

A method of calibrating a projection system heating model to predict an aberration in a projection system in a lithographic apparatus, the method comprising passing exposure radiation through a projection system to expose one or more exposure fields on a substrate provided on a substrate table, making measurements of the aberration in the projection system caused by the exposure radiation, wherein the time period between measurements is less than the time period that would be taken to expose all exposure fields on the substrate.

An exposure apparatus arranged to project a radiation beam onto a target portion of a substrate, the exposure apparatus having: a first substrate holder configured to hold the substrate; a second substrate holder configured to hold the substrate; a sensor holder configured to hold a sensor and/or detector; a first measurement device having a first alignment system having an alignment sensor configured to measure positions of a substrate alignment mark on the substrate; a second measurement device having a second alignment system having a further alignment sensor configured to measure positions of the substrate alignment mark on the substrate; a first scale arranged on a lower surface of the first substrate holder; and a first encoder head arranged to cooperate with the first scale, the first encoder head located beneath the first alignment system and held by a stationary support.

A module for a projection exposure apparatus for semiconductor lithography includes at least one optical element arranged in a holder. At least one spacer is arranged between the holder and a further holder or a main body. The spacer is designed to semi-actively vary its extent. A method for positioning at least one holder in a projection exposure apparatus for semiconductor lithography includes using a semi-active spacer is to position the holder.

A method of manufacturing a semiconductor device by using an exposure apparatus having a reticle stage and a projection optical system includes a first period in which substrates are exposed by using a first reticle arranged on the reticle stage, a second period in which substrates are exposed by using a second reticle arranged on the reticle stage, and a third period which is between the first and second periods. The method includes changing, in at least part of the third period, the first reticle arranged on the reticle stage to the second reticle, and performing control, in the first and second periods, to adjust temperature distribution of an optical element of the projection optical system so as to reduce change in aberration of the projection optical system. The third period is shorter than the first period.