Abstract: In an embodiment, a lithographic projection apparatus has an off-axis image field and a concave refractive lens as the final element of the projection system. The concave lens can be cut-away in parts not used optically to prevent bubbles from being trapped under the lens.

Abstract: An optical system and detector capture a distribution of radiation modified by interaction with a target structure. The observed distribution is used to calculate a property of the structure (e.g. CD or overlay). A condition error (e.g. focus error) associated with the optical system is variable between observations. The actual condition error specific to each capture is recorded and used to apply a correction for a deviation of the observed distribution due to the condition error specific to the observation. The correction in one practical example is based on a unit correction previously defined with respect to a unit focus error. This unit correction can be scaled linearly, in accordance with a focus error specific to the observation.

Abstract: 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.

Abstract: A device manufacturing method includes: confining a liquid to an immersion space between a projection system and an object; starting application of an underpressure to an extraction unit to remove fluid from a position proximate an edge of the object before the immersion space moves onto the object; moving the support table along a route comprising a series of motions such that a plurality of target positions on the object pass under the projection system; projecting through the immersion space a beam onto the target portions as the target portions pass under the projection system, the projecting performed to account for a certain predetermined thermal profile in the object; and stopping application of the underpressure at a predetermined time after the immersion space moves off the object for the last time during the series of motions to at least partly induce the certain predetermined thermal profile in the object.

Abstract: Disclosed is an EUV system in which a source control loop is established to maintain and optimize debris flux while not unduly affecting optimum EUV generation conditions. One or more temperature sensors, e.g., thermocouples may be installed in the vessel to measure respective local gas temperatures. The respective local temperature as measured by the one or more thermocouples can be used as one or more inputs to the source control loop. The source control loop may then adjust the laser targeting to permit optimization of debris generation and deposition while not affecting EUV production, thus extending the lifetime of the source and its collector.

Abstract: A target formed on a substrate, the target having: an alignment structure; and a metrology structure; wherein the alignment structure comprises structures that are arranged to generate a beat pattern when the alignment structure is illuminated with source radiation. Advantageously, when the target is illuminated, the beat pattern that appears in an image of the target allows the target to be easily identified using a pattern recognition technique.

Abstract: Disclosed is a method of optimizing within an inspection apparatus, the position and/or size (and therefore focus) of a measurement illumination spot relative to a target on a substrate. The method comprises detecting scattered radiation from at least the target resultant from illuminating the target, for different sizes and/or positions of said illumination spot relative to the target; and optimizing said position and/or size of the measurement illumination spot relative to the target based on a characteristic of the detected scattered radiation for the different sizes and/or positions of said illumination spot relative to the target.

Abstract: An immersion lithographic apparatus is provided with a liquid confinement structure which defines at least in part a space configured to contain liquid between the projection system and the substrate. In order to reduce the crossing of the edge of the substrate which is being imaged (which can lead to inclusion of bubbles in the immersion liquid), the cross-sectional area of the space in a plane parallel to the substrate is made as small as possible. The smallest theoretical size is the size of the target portion which is imaged by the projection system. In an embodiment, the shape of a final element of the projection system is also changed to have a similar size and/or shape in a cross-section parallel to the substrate to that of the target portion.

Abstract: A method of measuring a parameter of a device manufacturing process is disclosed. The method includes measuring a target on a substrate by illuminating the target with measurement radiation and using an optical apparatus to detect the measurement radiation scattered by the target. The target has a target structure having a first periodic component and a second periodic component. The optical apparatus receives radiation resulting from diffraction of the measurement radiation from the target structure. The received radiation includes at least one diffraction order that would not be received from diffraction of the measurement radiation from the first periodic component alone nor from diffraction of the measurement radiation from the second periodic component alone.

Abstract: A radiation sensor apparatus for determining a position and/or power of a radiation beam, the radiation sensor apparatus including a chamber to contain a gas, one or more sensors, and a processor. The chamber has a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber generally along an axis, and exit the chamber through the second opening. Each of the one or more sensors is arranged to receive and detect radiation emitted from a region of the chamber around the axis. The processor is operable to use the radiation detected by the one or more sensors to determine a position and/or power of the radiation beam.

Abstract: A method for improving a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic apparatus, the method including: obtaining a first source of the lithographic apparatus; classifying the first source into a class among a plurality of possible classes, based on one or more numerical characteristics of the first source, using a machine learning model, by a computer; determining whether the class is among one or more predetermined classes; only when the class is among the one or more predetermined classes, adjusting one or more source design variables to obtain a second source.

Abstract: A method involving determining an etch bias for a pattern to be etched using an etch step of a patterning process based on an etch bias model, the etch bias model including a formula having a variable associated with a spatial property of the pattern or with an etch plasma species concentration of the etch step, and including a mathematical term including a natural exponential function to the power of a parameter that is fitted or based on an etch time of the etch step; and adjusting the patterning process based on the determined etch bias.

Abstract: As increasing numbers of layers, using increasing numbers of specific materials, are deposited on substrates, it becomes increasingly difficult to detect alignment marks accurately for, for example, applying a desired pattern onto a substrate using a lithographic apparatus, in part due to one or more of the materials used in one or more of the layers being wholly or partially opaque to the radiation used to detect alignment marks. In a first step, the substrate is illuminated with excitation radiation. In a second step, at least one effect associated with a reflected material effect scattered by a buried structure is measured. The effect may, for example, include a physical displacement of the surface of the substrate. In a third step, at least one characteristic of the structure based on the measured effect is derived.

Abstract: An overlay metrology target (600, 900, 1000) contains a plurality of overlay gratings (932-935) formed by lithography. First diffraction signals (740(1)) are obtained from the target, and first asymmetry values (As) for the target structures are derived. Second diffraction signals (740(2)) are obtained from the target, and second asymmetry values (As?) are derived. The first and second diffraction signals are obtained using different capture conditions and/or different designs of target structures and/or bias values. The first asymmetry signals and the second asymmetry signals are used to solve equations and obtain a measurement of overlay error. The calculation of overlay error makes no assumption whether asymmetry in a given target structure results from overlay in the first direction, in a second direction or in both directions. With a suitable bias scheme the method allows overlay and other asymmetry-related properties to be measured accurately, even in the presence of two-dimensional overlay structure.

Abstract: A pellicle that includes graphene is constructed and arranged for an EUV reticle. A multilayer mirror includes graphene as an outermost layer.

Abstract: A method, including printing an apparatus mark onto a structure while the structure is at least partly within a lithographic apparatus. The structure may be part of, or is located on, a substrate table, but is separate from a substrate to be held by the apparatus. The method further includes measuring the apparatus mark using a sensor system within the apparatus.

Abstract: An object table to support an object, the object table having a support body, an object holder to hold an object, an opening adjacent an edge of the object holder, and a channel in fluid communication with the opening via a passageway, wherein the channel is defined by a first material which is different to a second material defining the passageway.

Abstract: A substrate has first and second target structures formed by a lithographic process. Each target structure has a two-dimensional periodic structure formed in a single layer using first and second lithographic steps. The first target structure has features defined in the second lithographic step displaced relative to features defined in the first lithographic step by a first bias amount. The second target structure has features defined in the second lithographic step displaced relative to features defined in the first lithographic step by a second bias amount. An angle-resolved scatter spectrum of the first target structure and an angle-resolved scatter spectrum of the second target structure is obtained. A measurement of a parameter of a lithographic process is derived from the measurements using asymmetry found in the scatter spectra of the first and second target structures.

Abstract: Droplet generators, such as used in an EUV radiation source, and associated EUV radiation sources and lithographic apparatuses. A droplet generator can include a nozzle assembly to emit the fuel as droplets, the nozzle assembly being within a pressurized environment at substantially the same pressure as the fuel pressure within the droplet generator. A droplet generator can include an actuator in contact with and biased against a pump chamber by means of a biasing mechanism having an actuator support biased against the actuator. The actuator acts on the fuel within the pump chamber to create droplets. The actuator support has a material with a greater coefficient of thermal expansion than its surrounding structure, such that it is moveable within the surrounding structure at ambient temperature, but expands against the surrounding structure at an operating temperature, so as to clamp the actuator support against the surrounding structure at the operating temperature.

Abstract: A method including: obtaining a measurement of a metrology target on a substrate processed using a patterning process, the measurement having been obtained using measurement radiation; and deriving a parameter of interest of the patterning process from the measurement, wherein the parameter of interest is corrected by a stack difference parameter, the stack difference parameter representing an un-designed difference in physical configuration between adjacent periodic structures of the target or between the metrology target and another adjacent target on the substrate.