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 N setting of the adjustable transformation optics.

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.

A method of aligning a diffractive optical system, to be operated with an operating beam, comprises: aligning (558) the diffractive optical system using an alignment beam having a different wavelength range from the operating beam and using a diffractive optical element optimized (552) to diffract the alignment beam and the operating beam in the same (or a predetermined) direction. In an example, the alignment beam comprises infra-red (IR) radiation and the operating beam comprises soft X-ray (SXR) radiation. The diffractive optical element is optimized by providing it with a first periodic structure with a first pitch (pIR) and a second periodic structure with a second pitch (pSXR). After alignment, the vacuum system is pumped down (562) and in operation the SXR operating beam is generated (564) by a high harmonic generation (HHG) optical source pumped by the IR alignment beam’ optical source.

A device and method for producing light-exposed structures on a workpiece having a light-sensitive surface. An optical unit includes a light source and a diffraction grating for producing a strip-shaped illumination pattern having strips extending in a longitudinal direction and having a pattern width extending transversely. A device moves the surface of the workpiece and optical unit relative to each other according to a path sequence, which includes movement longitudinal paths to produce a first and second light-exposed structure having strips, which is oriented parallel to each other on the workpiece surface. The movement paths are mutually spaced apart by less than the pattern width and the light-exposed structures overlap in such a way that strips of the light-exposed structures lie on each other. To obtain good light exposure of the surface by the illumination pattern, the diffraction grating is set oblique to the surface of the workpiece that is light-exposed by the illumination pattern.

An extreme ultraviolet light condensation mirror may include a reflective surface formed in a concave shape and configured to diffract a laser beam incident from a first focal point and having a wavelength longer than a wavelength of extreme ultraviolet light. The reflective surface may be provided with a plurality of first reflection portions, a plurality of second reflection portions, a plurality of first stepped portions, and a plurality of second stepped portions. The first and second stepped portions may have such heights that the laser beam obtains phases opposite to each other through reflection at the first and second reflection portions adjacent to each other. The height of each first stepped portion may be equal to or higher than the height of each second stepped portion. The height of at least one of the first stepped portions may be higher than the height of each second stepped portion.

The disclosure relates to an optical module with first and second components, a supporting structure and an anticollision device. The first component is supported by the supporting structure and is arranged adjacent to and at a distance from the second component to form a gap. The supporting structure defines a path of relative movement, on which the first and second components move in relation to one another under the influence of a disturbance, a collision between collision regions of the first and second components occurring if the anticollision device is inactive. The anticollision device includes a first anticollision unit on the first component, which produces a first field, and a second anticollision unit on the second component, which is assigned to the first anticollision unit and produces a second field.

An overlay metrology target (T) is formed by a lithographic process. A first image (740(0)) of the target structure is obtained using with illuminating radiation having a first angular distribution, the first image being formed using radiation diffracted in a first direction (X) and radiation diffracted in a second direction (Y). A second image (740(R)) of the target structure using illuminating radiation having a second angular illumination distribution which the same as the first angular distribution, but rotated 90 degrees. The first image and the second image can be used together so as to discriminate between radiation diffracted in the first direction and radiation diffracted in the second direction by the same part of the target structure. This discrimination allows overlay and other asymmetry-related properties to be measured independently in X and Y, even in the presence of two-dimensional structures within the same part of the target structure.

Described is a metrology system for determining a characteristic of interest relating to at least one structure on a substrate, and associated method. The metrology system comprises a processor being configured to computationally determine phase and amplitude information from a detected characteristic of scattered radiation having been reflected or scattered by the at least one structure as a result of illumination of said at least one structure with illumination radiation in a measurement acquisition, and use the determined phase and amplitude to determine the characteristic of interest.

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.

An optical diffraction component is configured to suppress at least one target wavelength by destructive interference. The optical diffraction component includes at least three diffraction structure levels that are assignable to at least two diffraction structure groups. A first of the diffraction structure groups is configured to suppress a first target wavelength .sub.1. A second of the diffraction structure groups is configured to suppress a second target wavelength .sub.2, where (.sub.1.sub.2).sup.2/(.sub.1+.sub.2).sup.2<20%. A topography of the diffraction structure levels can be described as a superimposition of two binary diffraction structure groups. Boundary regions between adjacent surface sections of each of the binary diffraction structure groups have a linear course and are superimposed on one another at most along sections of the linear course.