A method for exposing a wafer substrate includes forming a reticle having a device pattern. A relative orientation between the device pattern and a mask field of an exposure tool is determined based on mask field utilization. The reticle is loaded on the exposure tool. The wafer substrate is rotated based on an orientation of the device pattern. Radiation is projected through the reticle onto the rotated wafer substrate by the exposure tool, thereby imaging the device pattern onto the rotated wafer substrate.

An illumination source apparatus (500), suitable for use in a metrology apparatus for the characterization of a structure on a substrate, the illumination source apparatus comprising: a high harmonic generation, HHG, medium (502); a pump radiation source (506) operable to emit a beam of pump radiation (508); and adjustable transformation optics (510) configured to adjustably transform the transverse spatial profile of the beam of pump radiation to produce a transformed beam (518) such that relative to the centre axis of the transformed beam, a central region of the transformed beam has substantially zero intensity and an outer region which is radially outwards from the centre axis of the transformed beam has a non-zero intensity, wherein the transformed beam is arranged to excite the HHG medium so as to generate high harmonic radiation (540), wherein the location of said outer region is dependent on an adjustment setting of the adjustable transformation optics.

The disclosure relates to a method for producing an illumination system for an EUV apparatus in and to an illumination system for an EUV apparatus

The invention relates to a device for determining the exposure energy during the exposure of an element in an optical system, in particular for microlithography, comprising an optical element, a diffractive structure which has a locally varying grating period, and an intensity sensor arrangement, wherein electromagnetic radiation diffracted at the diffractive structure during operation of the optical system, in at least one order of diffraction, is directed to the intensity sensor arrangement by way of total internal reflection effected in the optical element.

A method of controlling a feedback system with a data matching module of an extreme ultraviolet (EUV) radiation source is disclosed. The method includes obtaining a slit integrated energy (SLIE) sensor data and diffractive optical elements (DOE) data. The method performs a data match, by the data matching module, of a time difference of the SLIE sensor data and the DOE data to identify a mismatched set of the SLIE sensor data and the DOE data. The method also determines whether the time difference of the SLIE sensor data and the DOE data of the mismatched set is within an acceptable range. Based on the determination, the method automatically validates a configurable data of the mismatched set such that the SLIE sensor data of the mismatched set is valid for a reflectivity calculation.

Disclosed is a method of measuring a target, and a metrology apparatus. In one arrangement the target comprises a layered structure. The layered structure has a first target structure in a first layer and a second target structure in a second layer. The method comprises illuminating the target with measurement radiation using an illumination profile in the illumination pupil (u) that is offset from an imaginary line (IL) in the illumination pupil passing through the optical axis, to allow propagation to a detection region of the detection pupil of an allowed order (v.sub.2, v.sub.4) of a predetermined diffraction order while limiting propagation to the detection region of an equal and opposite order (v.sub.1, v.sub.3) of that predetermined diffraction order. Scattered radiation of plural double-diffracted allowed diffraction orders (w.sub.2, w.sub.4) is detected. A characteristic of the lithographic process is calculated using the detected scattered radiation of the predetermined diffraction orders.

Methods and apparatus for determining an intensity profile of a radiation beam. The method comprises providing a diffraction structure, causing relative movement of the diffraction structure relative to the radiation beam from a first position wherein the radiation beam does not irradiate the diffraction structure to a second position wherein the radiation beam irradiates the diffraction structure, measuring, with a radiation detector, diffracted radiation signals produced from diffraction of the radiation beam by the diffraction structure as the diffraction structure transitions from the first position to the second position or vice versa, and determining the intensity profile of the radiation beam based on the measured diffracted radiation signals.

A method for exposing a wafer substrate includes forming a reticle having a device pattern. A relative orientation between the device pattern and a mask field of an exposure tool is determined based on mask field utilization. The reticle is loaded on the exposure tool. The wafer substrate is rotated based on an orientation of the device pattern. Radiation is projected through the reticle onto the rotated wafer substrate by the exposure tool, thereby imaging the device pattern onto the rotated wafer substrate.

The disclosure relates to a method for producing an illumination system for an EUV apparatus in and to an illumination system for an EUV apparatus.

An imaging optical unit comprises a plurality of minors for imaging an object field into an image field. The imaging optical unit has an image-side numerical aperture greater than 0.55. Each mirror is configured so that it can be measured by a testing optical unit having at least one DOE with a predetermined maximum diameter for test wavefront generation. For the complete measurement of all reflection surfaces of the minors, a maximum number of DOEs of the testing optical unit and/or a maximum number of DOE test positions of the at least one DOE of the testing optical unit comes into play, which is no more than five times the number of minors in the imaging optical unit. The result is an imaging optical unit in which a testing-optical measurement remains manageable even in the case of a design with an image-side numerical aperture which is relatively large.