A method for measuring a substrate for semiconductor lithography using a measuring device, wherein the measuring device comprises a recording device for capturing at least a partial region of the substrate and, wherein the distance between the substrate and an imaging optical unit of the recording device is varied while the partial region is captured by the recording device.

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.

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.

A measuring system (MS) configured to measure a projection radiation property representing an aberration level at a plurality of spaced apart measuring points distributed in the image field; and an operating control system with at least one manipulator operatively connected to an optical element of a projection exposure system to modify imaging properties of the projection exposure system based on measurement results generated by the measuring system. In a measuring point distribution calculation (MPDC), a measuring point distribution defining a number and positions of measuring points is used. The MPDC is performed under boundary conditions representing at least: (i) manipulation capacities of the operating control system; (ii) measuring capacities of the measuring system; and (iii) predefined use case scenarios defining a set of representative use cases. Each use case corresponds to a specific aberration pattern generated by the projection exposure system under a predefined set of use conditions.

A measurement apparatus (10) for measuring a wavefront aberration of an imaging optical system (12) includes (i) a measurement wave generating module (24) which generates a measurement wave (26) radiated onto the optical system and which includes an illumination system (30) illuminating a mask plane (14) with an illumination radiation (32), as well as coherence structures (36) arranged in the mask plane, and (ii) a wavefront measurement module (28) which measures the measurement wave after passing through the optical system and determines from the measurement result, with an evaluation device (46), a deviation of the wavefront of the measurement wave from a desired wavefront. The evaluation device (46) determines an influence of an intensity distribution (70) of the illumination radiation in the region of the mask plane on the measurement result and, when determining the deviation of the wavefront, utilizes the influence of the intensity distribution.

A method involving: obtaining a process model of a patterning process that includes or accounts for an average optical aberration of optical systems of a plurality of apparatuses for use with a patterning process; and applying the process model to determine an adjustment to a parameter of the patterning process to account for the average optical aberration.

A metrology apparatus (302) includes a higher harmonic generation (HHG) radiation source for generating (310) EUV radiation. Operation of the HHG source is monitored using a wavefront sensor (420) which comprises an aperture array (424, 702) and an image sensor (426). A grating (706) disperses the radiation passing through each aperture so that the image detector captures positions and intensities of higher diffraction orders for different spectral components and different locations across the beam. In this way, the wavefront sensor can be arranged to measure a wavefront tilt for multiple harmonics at each location in said array. In one embodiment, the apertures are divided into two subsets (A) and (B), the gratings (706) of each subset having a different direction of dispersion. The spectrally resolved wavefront information (430) is used in feedback control (432) to stabilize operation of the HGG source, and/or to improve accuracy of metrology results.

The disclosed method involves: recording, under illumination of a diffractive measurement structure via an illumination device, a plurality of diffraction images which differ from one another in terms of the region of the measurement structure that contributes to the respective diffraction image, and ascertaining transmission properties and/or reflection properties of the diffractive measurement structure based on the plurality of diffraction images, wherein the steps of recording a plurality of diffraction images and of ascertaining transmission properties and/or reflection properties of the diffractive measurement structure in a plurality of recording sequences are carried out repeatedly in a plurality of recording sequences, wherein these recording sequences differ from one another with respect to the illumination angles that are respectively set during the illumination of the diffractive measurement structure and at which the diffractive measurement structure is illuminated.

Some implementations described herein provide an exposure tool. The exposure tool includes a reticle deformation detector and one or more processors configured to obtain, via the reticle deformation detector, reticle deformation information associated with a reticle during a scanning process for scanning multiple fields of a wafer. The one or more processors determine, based on the reticle deformation information, a deformation of the reticle at multiple times during the scanning process, and perform, based on the deformation of the reticle at the multiple times, one or more adjustments of one or more components of the exposure tool during the scanning process.