Abstract: The present disclosure relates to apparatus and methods for assessing samples using charged particles. In one arrangement, a degassing action is performed by exposing a target area of a sample with charged particles to stimulate degassing. A rate of degassing from the target area is measured during the degassing action. Initiation of an assessing of the sample is controlled based on a characteristic of the measured rate of degassing. The assessing of the sample comprising exposing the target area with charged particles and detecting signal charged particles from the target area.

Abstract: An assessment method comprising: using an assessment apparatus to generate assessment signals representing a property of a surface of a sample; processing the assessment signals to identify candidate defects and outputting a candidate defect signal; monitoring the status of the assessment apparatus for error conditions and generating a status signal indicating any error conditions during functioning of the assessment apparatus; and analysing the candidate defect signal to determine if the candidate defects are real defects; wherein analysis of a candidate defect is not completed if the status signal indicates that the assessment signal(s) and/or the candidate defect signal corresponding to the candidate defect would have been affected by an error condition.

Abstract: An optical apparatus for a reticle stage of a lithographic apparatus is disclosed. The optical apparatus comprises: a reflective optical element comprising a surface for exposure to radiation; at least two electrodes located at the surface; and a measurement system configured to measure one or more electrical characteristics of the reflective optical element between the at least two electrodes. Also disclosed is a method of measuring a degradation of a reflective optical element having a surface for exposure to radiation in a lithographic apparatus, the method comprising: providing at least two electrodes at the surface of the reflective optical element; and measuring one or more electrical characteristics of the reflective optical element between the at least two electrodes.

Abstract: A controller system is configured to control a plant and comprising a feedforward controller to provide, based on a reference state signal, a feedforward signal to the plant, and a feedback controller system to provide a feedback signal to the plant, based on a difference between the reference state signal and a plant state signal representing an actual state of the plant. The feedback controller system comprises an integrator, a trajectory generator, and a selector. The feedback controller system is configured to operate as a function of the reference state in a first control mode or a second control mode, wherein the feedback controller system, in the first control mode, operates the selector to select the trajectory generator output signal generated by the trajectory generator, and wherein the feedback controller system, in the second control mode, operates the selector to select the integrator output signal generated by the integrator.

Abstract: Systems and methods for training a machine learning model to classify defects with utility-function-based active learning are described. In one embodiment, one or more non-transitory, machine-readable mediums are configured to cause a processor to at least determine a utility function value for unclassified measurement images, based on a machine learning model, wherein the machine learning model is trained using a pool of labeled measurement images. Based on a determination that the utility function value for a given unclassified measurement image is less than a threshold value, the unclassified measurement image is output for classification without the use of the machine learning model. The unclassified measurement images classified via the classification without the use of the machine learning model are added to the pool of labeled measurement images. The machine learning model is trained based on the measurement images classified via the classification without the use of the machine learning model.

Abstract: A target delivery system for an extreme ultraviolet (EUV) light source is disclosed. The system includes: a conduit including an orifice configured to fluidly couple to a reservoir; an actuator configured to mechanically couple to the conduit such that motion of the actuator is transferred to the conduit; and a control system coupled to the actuator, the control system being configured to: determine an indication of pressure applied to target material in the reservoir, and control the motion of the actuator based on the determined indication of applied pressure. Moreover, techniques for operating a supply system are disclosed. For example, one or more characteristics of the supply system are determined, and an actuator that is mechanically coupled to the supply system is controlled based on the one or more determined characteristics such that an orifice of the supply system remains substantially free of material damage during operational use.

Abstract: A method for training a machine learning model configured to predict a substrate image corresponding to a printed pattern of a substrate as measured via a metrology tool. The method involves obtaining a training data set including (i) metrology data of the metrology tool used to measure the printed pattern of the substrate, and (ii) a representation of a mask pattern employed for imaging the printed pattern on the substrate; and training, based on the training data set, a machine learning model to predict the substrate image of the substrate as measured by the metrology tool such that a cost function is improved, wherein the cost function includes a relationship between the predicted substrate image and the metrology data.

Abstract: The invention provides a method for calibration of an optical measurement system, which may be a heterodyne interferometer system, wherein a first optical axis and a second optical axis have a different optical path length, the method comprises: ?measuring a first measurement value along the first optical axis using a first measurement beam, ?measuring a second measurement value along the second optical axis using a second measurement beam, ?changing a wavelength of the first measurement beam and the second measurement beam, ?measuring a further first measurement value along the first optical axis using the first measurement beam with changed wavelength, measuring a further second measurement value along the second optical axis using the second measurement beam with changed wavelength, ?determining a cyclic error of the optical measurement system on the basis of the measured values, and ?storing a corrective value based on the cyclic error.

Abstract: Disclosed is a method of manufacturing a reflector. The method comprises polishing (520) at least the uppermost surface of the uppermost substantially flat substrate of a plurality of substantially flat substrates, deforming (530) each substantially flat substrate into the desired shape, and bonding (540) the deformed substrates together to form said reflector. In an embodiment, the deforming and bonding is performed together using a mold.

Abstract: A compact dual pass interferometer for a plane mirror interferometer configured to receive an input radiation beam from a light source. An optical component has a partially reflective surface arranged to reflect a first portion of the input radiation beam to follow a first optical path directed towards an output terminal and further arranged to transmit a second portion of the input radiation beam to follow a second optical path, directed towards a first location on a reflective target surface and back to the partially reflective surface, then to a second location on the reflective target surface and back to the partially reflective surface, whereupon the second optical path is directed through the partially reflective surface to be recombined with the first optical path to provide a recombined optical path configured to provide an output radiation beam. The output terminal configured to deliver the output radiation beam to a detector.

Abstract: A first diffusor configured to receive and transmit radiation has a plurality of layers, each layer arranged to change an angular distribution of EUV radiation passing through it differently. A second diffusor configured to receive and transmit radiation has a first layer and a second layer. The first layer is formed from a first material, the first layer including a nanostructure on at least one surface of the first layer. The second layer is formed from a second material adjacent to the at least one surface of the first layer such that the second layer also includes a nanostructure. The second material has a refractive index that is different to a refractive index of the first layer. The diffusors may be configured to receive and transmit EUV radiation.

Abstract: An apparatus including: a first gripping member having a first magnetic element and moveable between a first position and a second position; a first biasing member configured to bias the first gripping member toward the first position; and a second magnetic element selectively operable in a first mode, in which the second magnetic element interacts with the first magnetic element to overcome the first biasing member and move the first gripping member to the second position, and a second mode, in which the second magnetic element does not overcome the first biasing member such that the first gripping member rests in the first position.

Abstract: A supercontinuum radiation source including a pump laser arrangement for generating pump radiation and including a plurality of pump laser heads; a radiation combiner for combining the respective pump radiation from each pump laser head, and a non-linear fiber for receiving the pump radiation so as to excite a working medium within the non-linear fiber to generate supercontinuum radiation. Each pump laser head has dimensions no greater than 5 cm in any direction. Alternatively, or in addition the supercontinuum radiation source further includes a control arrangement for controlling the pump laser arrangement, the control arrangement configured for non-simultaneous emission of pulses from each pump laser head.

Abstract: Disclosed is a pupil shaping arrangement for obtaining a defined pupil intensity profile for a metrology illumination beam configured for use in a metrology application. The pupil shaping arrangement comprises an engineered diffuser (ED) having a defined far-field profile configured to impose said defined pupil intensity profile on said metrology illumination beam. The pupil shaping arrangement may further comprise a multimode fiber (MMF) and be configured to reduce spatial coherence of coherent radiation.

Abstract: An exposure apparatus arranged to project a radiation beam onto a target portion of a substrate, the exposure apparatus having: a first substrate holder configured to hold the substrate; a second substrate holder configured to hold the substrate; a sensor holder configured to hold a sensor and/or detector; a first measurement device having a first alignment system having an alignment sensor configured to measure positions of a substrate alignment mark on the substrate; a second measurement device having a second alignment system having a further alignment sensor configured to measure positions of the substrate alignment mark on the substrate; a first scale arranged on a lower surface of the first substrate holder; and a first encoder head arranged to cooperate with the first scale, the first encoder head located beneath the first alignment system and held by a stationary support.

Abstract: A method of generating control actions for controlling a production system, such as by transmitting the control actions to a control system of the production system. The method includes receiving, by a memory unit, a set of observation data characterizing a current state of the production system; processing, by a first neural network module of the memory unit, an input based on at least part of the observation data to generate encoded observation data; updating, by a second neural network module of the memory unit, history information stored in an internal memory of the second module using an input based on at least part of the observation data; obtaining, based on the encoded observation data and the updated history information, state data; and generating, based on the state data, one or more control actions.

Abstract: Systems and methods for training a machine learning model for defect detection include obtaining training data including an inspection image of a fabricated integrated circuit (IC) and design layout data of the IC, and training a machine learning model using the training data. The machine learning model includes a first autoencoder and a second autoencoder. The first autoencoder includes a first encoder and a first decoder. The second autoencoder includes a second encoder and a second decoder. The second decoder is configured to obtain a first code outputted by the first encoder. The first decoder is configured to obtain a second code outputted by the second encoder.

Abstract: A method of training a generator model comprising: using the generator model to generate the predictive data based on the first measured data, wherein the first measured data and the predictive data can be used to form images of the sample; pairing subsets of the first measured data with subsets of the predictive data, the subsets corresponding to locations within the images of the sample that can be formed from the first measured data and the predictive data; using a discriminator to evaluate a likelihood that the predictive data comes from a same data distribution as second measured data measured from a sample after an etching process; and training the generator model based on: correlation for the pairs corresponding to a same location relative to correlation for pairs corresponding to different locations, the correlation being the correlation between the paired subsets of data, and the likelihood evaluated by the discriminator.

Abstract: A method for processing images for metrology using a charged particle beam tool may include obtaining, from the charged particle beam tool, an image of a portion of a sample. The method may further include processing the image using a first image processing module to generate a processed image. The method may further include determining image quality characteristics of the processed image and determining whether the image quality characteristics of the processed image satisfy predetermined imaging criteria. The method may further include in response to the image quality characteristics of the processed image not satisfying the imaging criteria, updating a tuning condition of the charged-particle beam tool, acquiring an image of the portion of the sample using the charged-particle beam tool that has the updated tuning condition, and processing the acquired image using the first image processing module to enable the processed acquired image to satisfy the predetermined imaging criteria.

Abstract: An assembly for a lithographic apparatus, wherein the assembly is configured to heat a pellicle membrane by one of or a combination selected from: i) provision of heated gas, ii) radiative heating, iii) resistive heating, and/or iv) inductive heating, and/or by illuminating the pellicle membrane with light having a wavelength of from around 91 nm to around 590 nm. Also a method of extending the operative lifespan of a pellicle membrane, the method including heating at least a portion of a pellicle membrane when illuminated by EUV by one of or a combination selected from: i) providing heated gas, ii) radiative heating, iii) resistive heating, and/or iv) inductive heating to effect heating of the at least one portion of the pellicle membrane, and/or by illuminating the pellicle membrane with light having a wavelength of from around 91 nm to around 590 nm.