Abstract: An optical measurement method using an optical sensor apparatus (15), the optical sensor apparatus comprising an optical element (20) comprising a mark (22) configured to selectively transmit incident radiation (24), a photodetector (26) configured to receive radiation transmitted by the mark and provide an output signal that is indicative of the received radiation, and a support (30) which supports the optical element and is in thermal contact with the optical element. A thermal conductivity of the support is greater than a thermal conductivity of the optical element and a coefficient of thermal expansion of the support is greater than a coefficient of thermal expansion of the optical element. The method comprises performing a first measurement using the optical sensor apparatus, the first measurement including illuminating the mark with radiation. The temperature of the optical element changes during the first measurement.

Abstract: A fluid handling structure for a lithographic apparatus configured to contain immersion fluid to a region, the fluid handling structure having, at a boundary of a space: at least one gas knife opening in a radially outward direction of the space; and at least one gas supply opening in the radially outward direction of the at least gas knife opening relative to the space. The gas knife opening and the gas supply opening both provide substantially pure CO2 gas so as to provide a substantially pure CO2 gas environment adjacent to, and radially outward of, the space.

Abstract: Overlay error of a lithographic process is measured using a plurality of target structures, each target structure having a known overlay bias. A detection system captures a plurality of images (740) representing selected portions of radiation diffracted by the target structures under a plurality of different capture conditions (?1, ?2). Pixel values of the captured images are combined (748) to obtain one or more synthesized images (750). A plurality of synthesized diffraction signals are extracted (744) from the synthesized image or images, and used to calculate a measurement of overlay. The computational burden is reduced compared with extracting diffraction signals from the captured images individually. The captured images may be dark-field images or pupil images, obtained using a scatterometer.

Abstract: A method of defect validation for a device manufacturing process, the method including: obtaining a first image of a pattern processed into an area on a substrate using the device manufacturing process under a first condition; obtaining a metrology image from the area; aligning the metrology image and the first image; and determining from the first image and the metrology image whether the area contains a defect, based on one or more classification criteria.

Abstract: Offline metrology measurements are performed on substrates that have been subjected to lithographic processing. Model parameters are calculated by fitting the measurements to an extended high-order substrate model defined using a combination of basis functions that include an edge basis function related to a substrate edge. A radial edge basis function may be expressed in terms of distance from a substrate edge. The edge basis function may, for example, be an exponential decay function or a rational function. Lithographic processing of a subsequent substrate is controlled using the calculated high-order substrate model parameters, in combination with low-order substrate model parameters obtained by fitting inline measurements to a low order model.

Abstract: In a dark-field metrology method using a small target, a characteristic of an image of the target, obtained using a single diffraction order, is determined by fitting a combination fit function to the measured image. The combination fit function includes terms selected to represent aspects of the physical sensor and the target. Some coefficients of the combination fit function are determined based on parameters of the measurement process and/or target. In an embodiment the combination fit function includes jinc functions representing the point spread function of a pupil stop in the imaging system.

Abstract: A lithographic apparatus includes a number of sensors for measuring positions of features on a substrate prior to applying a pattern. Each sensor includes an imaging optical system. Position measurements are extracted from pixel data supplied by an image detector in each sensor. The imaging optical system includes one or more light field modulating elements and the processor processes the pixel data as a light-field image to extract the position measurements. The data processor may derive from each light-field image a focused image of a feature on the substrate, measuring positions of several features simultaneously, even though the substrate is not at the same level below all the sensors. The processor can also include corrections to reduce depth dependency of an apparent position of the feature include a viewpoint correction. The data processor can also derive measurements of heights of features on the substrate.

Abstract: A measurement system to determine a deformation of an object having a front surface, a back surface and a pattern. The measurement system includes a processor system and an interferometer system. The interferometer system has a radiation source and a detector system. The source is configured to emit, to each of a plurality of locations on the object, measurement beams in order to generate, at each of the respective plurality of locations, reflected measurement beams off the front and back surfaces of the object respectively. The detector system is configured to receive the respective reflected measurement beams and output signals representative of the received reflected measurement beams to the processor system. The processor system is configured to receive the signals; determine, based on the signals as received, a characteristic of the object; and determine a deformation of the pattern based on the characteristic.

Abstract: Methods of training machine learning models related to a patterning process, including a method for training a machine learning model configured to predict a mask pattern. The method including obtaining (i) a process model of a patterning process configured to predict a pattern on a substrate, wherein the process model comprises one or more trained machine learning models, and (ii) a target pattern, and training the machine learning model configured to predict a mask pattern based on the process model and a cost function that determines a difference between the predicted pattern and the target pattern.

Abstract: A method for manufacturing a membrane assembly for EUV lithography, the method including: providing a stack including a membrane layer between a supporting substrate and an attachment substrate, wherein the supporting substrate includes an inner region and a border region; processing the stack, including selectively removing the inner region of the supporting substrate, to form a membrane assembly comprising: a membrane formed from at least the membrane layer; and a support holding the membrane, the support formed at least partially from the border region of the supporting substrate. The attachment substrate can be bonded to the rest of the stack.

Abstract: A method including obtaining an image of a plurality of structures on a substrate, wherein each of the plurality of structures is formed onto the substrate by transferring a corresponding pattern of a design layout; obtaining, from the image, a displacement for each of the structures with respect to a reference point for that structure; and assigning each of the structures into one of a plurality of groups based on the displacement.

Abstract: An optical inspection apparatus, including: an optical metrology tool configured to measure structures, the optical metrology tool including: an electromagnetic (EM) radiation source configured to direct a beam of EM radiation along an EM radiation path; and an adaptive optical system disposed in a portion of the EM radiation path and configured to adjust a shape of a wave front of the beam of EM radiation, the adaptive optical system including: a first aspherical optical element; a second aspherical optical element adjacent the first aspherical optical element; and an actuator configured to cause relative movement between the first optical element and the second optical element in a direction different from a beam axis of the portion of the EM radiation path.

Abstract: A support table for a lithographic apparatus, the support table having a support section and a conditioning system, wherein the support section, the conditioning system, or both, is configured such that heat transfer to or from a substrate supported on the support table, resulting from the operation of the conditioning system, is greater in a region of the substrate adjacent an edge of the substrate than it is in a region of the substrate that is at the center of the substrate.

Abstract: A method for generating metrology sampling scheme for a patterning process, the method including: obtaining a parameter map of a parameter of a patterning process for a substrate; decomposing the parameter map to generate a fingerprint specific to an apparatus of the patterning process and/or a combination of apparatuses of the patterning process; and based on the fingerprint, generating a metrology sampling scheme for a subsequent substrate at the apparatus of the patterning process and/or the combination of apparatuses of the patterning process, wherein the sampling scheme is configured to distribute sampling points on the subsequent substrate so as to improve a metrology sampling density.

Abstract: A method for determining an overlapping process window (OPW) of an area of interest on a portion of a design layout for a device manufacturing process for imaging the portion onto a substrate, the method including: obtaining a plurality of features in the area of interest; obtaining a plurality of values of one or more processing parameters of the device manufacturing process; determining existence of defects, probability of the existence of defects, or both in imaging the plurality of features by the device manufacturing process under each of the plurality of values; and determining the OPW of the area of interest from the existence of defects, the probability of the existence of defects, or both.

Abstract: A method of reconstructing a characteristic of a structure formed on a substrate by a lithographic process, and an associated metrology apparatus. The method includes combining measured values of a first parameter associated with the lithographic process to obtain an estimated value of the first parameter; and reconstructing at least a second parameter associated with the characteristic of the structure using the estimated value of the first parameter and a measurement of the structure. The combining may involve modeling a variation of the first parameter to obtain a parameter model or fingerprint of the first parameter.

Abstract: A mirror array, at least some of the mirrors of the array comprising a reflective surface and an arm which extends from a surface opposite to the reflective surface, wherein the mirror array further comprises a support structure provided with a plurality of sensing apparatuses, the sensing apparatuses being configured to measure gaps between the sensing apparatuses and the arms which extend from the mirrors.

Abstract: An acoustic scatterometer 502 has an acoustic source 520 operable to project acoustic radiation 526 onto a periodic structure 538 and 540 formed on a substrate 536. An acoustic detector 518 is operable to detect the ?1st acoustic diffraction order 528 diffracted by the periodic structure 538 and 540 while discriminating from specular reflection (0th order 532). Another acoustic detector 522 is operable to detect the +1st acoustic diffraction order 530 diffracted by the periodic structure, again while discriminating from the specular reflection (0th order 532). The acoustic source and acoustic detector may be piezo transducers. The angle of incidence of the projected acoustic radiation 526 and location of the detectors 518 and 522 are arranged with respect to the periodic structure 538 and 540 such that the detection of the ?1st and +1st acoustic diffraction orders 528 and 530 discriminates from the 0th order specular reflection 532.

Abstract: A method of controlling a lithographic apparatus to manufacture a plurality of devices, the method including: obtaining a parameter map representing a parameter variation across a substrate by measuring the parameter at a plurality of points on the substrate; decomposing the parameter map into a plurality of components, including a first parameter map component representing parameter variations associated with the device pattern and one or more further parameter map components representing other parameter variations; deriving a scale factor, configured to correct for errors in measurement of the parameter variation, from measurements of a second parameter of a substrate; and controlling the lithographic apparatus using the parameter map and scale factor to apply a device pattern at multiple locations across the substrate.

Abstract: An optical system comprising: an illumination system configured, to form a periodic illumination mode comprising radiation in a pupil plane of the optical system having a spatial intensity profile which is periodic in at least one direction, a measurement system configured to measure a dose of radiation which is received in an field plane of the optical system as a function of position in the field plane, and a controller configured to: select one or more spatial frequencies in the field plane at which variation in the received dose of radiation as a function of position is caused by speckle, and determine a measure of the variation of the received dose of radiation as a function of position at the selected one or more spatial frequencies, the measure of the variation in the received dose being indicative of speckle in the field plane.