Disclosed is a method of measuring focus performance of a lithographic apparatus. The method comprises using the lithographic apparatus to print at least one focus metrology pattern on a substrate, the printed focus metrology pattern comprising at least a first periodic array of features, and using inspection radiation to measure asymmetry between opposite portions of a diffraction spectrum for the first periodic array in the printed focus metrology pattern. A measurement of focus performance is derived based at least in part on the asymmetry measured. The first periodic array comprises a repeating arrangement of a space region having no features and a pattern region having at least one first feature comprising sub-features projecting from a main body and at least one second feature; and wherein the first feature and second feature are in sufficient proximity to be effectively detected as a single feature during measurement. A patterning device comprising said first periodic array is also disclosed.

A lithographic process is one that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. During the lithographic process, the focus needs to be controlled. There is disclosed a method for determining a fingerprint of a performance parameter associated with a substrate, such as a focus value to be used during the lithographic process. A reference fingerprint of the performance parameter is determined for a reference substrate. A reference substrate parameter of the reference substrate is determined. A substrate parameter for a substrate, such as a substrate with product structures, is determined. Subsequently, the fingerprint of the performance parameter is determined based on the reference fingerprint, reference substrate parameter and the substrate parameter. The fingerprint may then be used to control the lithographic process.

An image-based overlay metrology system is disclosed. The system includes a controller couplable to a metrology sub-system. The controller is configured to receive a set of image signals of a first metrology target disposed on the sample from the metrology sub-system and determine a plurality of harmonic detectivity metric values by calculating a harmonic detectivity metric value for each of the plurality of image signals. The controller is also configured to identify a set of optical measurement conditions of the metrology sub-system based on the plurality of harmonic detectivity metric values, wherein the set of optical measurement conditions define a recipe for optical metrology measurements of the metrology sub-system. The controller then provides the recipe to the metrology sub-system for execution of one or more optical metrology measurements of one or more additional metrology targets.

A diffraction pattern guided source mask optimization (SMO) method that includes determining a source variable region from a diffraction pattern. The source variable region corresponds to one or more areas of a diffraction pattern in a pupil for which one or more pupil variables are to be adjusted. The source variable region in the diffraction pattern includes a plurality of pixels in an image of a selected region of interest in the diffraction pattern. Determining the source variable region can include binarization of the plurality of pixels in the image such that individual pixels are either included in the source variable region or excluded from the source variable region. The method can include adjusting the one or more pupil variables for the one or more areas of the pupil that correspond to the source variable region; and rendering a final pupil based on the adjusted one or more pupil variables.

A method of measuring misregistration in the manufacture of semiconductor device wafers including providing a multilayered semiconductor device wafer including at least a first layer and a second layer including at least one misregistration measurement target including a first periodic structure formed together with the first layer having a first pitch and a second periodic structure formed together with the second layer having a second pitch, imaging the first layer and the second layer at a depth of focus and using light having at least one first wavelength that causes images of both the first layer and the second layer to appear in at least one plane within the depth of focus and quantifying offset in the at least one plane between the images of the first layer and the second layer, thereby to calculate misregistration of the first layer and the second layer.

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.

In one embodiment, a multi charged particle beam writing apparatus includes an objective lens adjusting focus positions of multiple beams, an astigmatism correction element correcting astigmatism of the multiple beams, an inspection aperture allowing one of the multiple beams to pass therethrough, a deflector deflecting the multiple beams and causing the multiple beams to scan over the inspection aperture, a current detector detecting beam currents of the individual multiple beams after passing through the inspection aperture, a beam image formation unit forming a beam image based on the detected beam currents, a feature amount calculation unit generating a first waveform and a second waveform by adding brightnesses of the beam image in a first direction and in a second direction, and calculating a first and a second feature amounts from the first and the second waveforms, and a parameter calculation unit calculating an exciting parameter that is to be set for the astigmatism correction element based on the first feature amount and the second feature amount.

A method, involving determining a first distribution of a first parameter associated with an error or residual in performing a device manufacturing process; determining a second distribution of a second parameter associated with an error or residual in performing the device manufacturing process; and determining a distribution of a parameter of interest associated with the device manufacturing process using a function operating on the first and second distributions. The function may include a correlation.

Disclosed is a method for selecting a structure for focus monitoring. The method comprises: simulating a Bossung response with focus of a focus dependent parameter, for one or more different structures; and selecting a structure for focus monitoring in a manufacturing process based on the results of said simulating step. The simulating step may be performed using a computational lithography simulation.

A method for configuring an apparatus for providing structures to a layer on a substrate, the method including: obtaining first data including substrate specific data as measured and/or modeled before the providing of the structures to the layer on the substrate; and determining a configuration of the apparatus for at least two different control regimes based on the first data and the use of a common merit function including parameters associated with the at least two control regimes.