Abstract: In a method of determining the focus of a lithographic apparatus used in a lithographic process on a substrate, the lithographic process is used to form a structure on the substrate, the structure having at least one feature which has an asymmetry in the printed profile which varies as a function of the focus of the lithographic apparatus on the substrate. A first image of the periodic structure is formed and detected while illuminating the structure with a first beam of radiation. The first image is formed using a first part of non-zero order diffracted radiation. A second image of the periodic structure is formed and detected while illuminating the structure with a second beam of radiation. The second image is formed using a second part of the non-zero order diffracted radiation which is symmetrically opposite to the first part in a diffraction spectrum.

Abstract: A lithographic apparatus includes a support frame which is supported by a base via a vibration isolation system; a projection system arranged to transfer a pattern from a patterning device onto a substrate, wherein the projection system includes a first frame which is spring-supported by the support frame; and an active damping system configured to damp movement of the first frame, including: a first sensor system configured to provide a first sensor output representative of absolute movement of the first frame, a first actuator system arranged to apply a force between the first frame and the support frame, and a control system configured to provide a drive signal to the first actuator system based on the first sensor output.

Abstract: A lithographic apparatus has an alignment system including a radiation source configured to convert narrow-band radiation into continuous, flat and broad-band radiation. An acoustically tunable narrow pass-band filter filters the broad-band radiation into narrow-band linearly polarized radiation. The narrow-band radiation may be focused on alignment targets of a wafer so as to enable alignment of the wafer. In an embodiment, the filter is configured to modulate an intensity and wavelength of radiation produced by the radiation source and to have multiple simultaneous pass-bands. The radiation source generates radiation that has high spatial coherence and low temporal coherence.

Abstract: A lithographic apparatus includes a substrate table constructed to hold a substrate, a projection system configured to project a patterned radiation beam through an opening and onto a target portion of the substrate, and a conduit having an outlet in the opening. The conduit is configured to deliver gas to the opening. The lithographic apparatus further includes a cooling apparatus controlled by a control system. The cooling apparatus is configured to cool the gas such that gas which travels from the opening to the substrate has a predetermined temperature when the gas is incident upon the substrate.

Abstract: A position measurements system to measure a position of a movable object with respect to another object includes two or more one dimensional (1D) encoder heads mounted on one of the movable object and the other object and each capable of emitting a measurement beam along a measurement direction, one or more reference targets mounted on the other of the movable object and the other object, each reference target including a planar surface with a grid or grating to cooperate with the two or more one dimensional (1D) encoder heads, and a processor to calculate a position of the object on the basis of outputs of the two or more 1D encoder heads, wherein the measurement direction of each of the two or more 1D encoder heads is non-perpendicular to the planar surface of the respective reference target.

Abstract: Improved convergence in the volume-integral method (VIM) of calculating electromagnetic scattering properties of a structure is achieved by numerically solving a volume integral equation for a vector field, F, rather than the electric field, E. The electric field, E, is determined from the vector field, F, after solving of the volume integral equation. The vector field, F, may be related to the electric field, E, by a change of basis, and may be continuous at material boundaries where the electric field, E, has discontinuities. Convolutions of the vector field, F, are performed using convolution operators according to the finite Laurent rule, which allows for efficient matrix-vector products using Fast Fourier Transforms. An invertible convolution-and-change-of-basis operator, C, is configured to transform the vector field, F, to the electric field, E, by performing a change of basis according to material and geometric properties of the periodic structure.

Abstract: An EUV radiation source comprising a fuel supply configured to deliver droplets of fuel to a plasma formation location, and a collector configured to collect EUV radiation emitted by a plasma at the plasma formation location, wherein the collector has a reflective surface that is a modified ellipsoid shape, the modified ellipsoid shape providing improved intensity uniformity of collected EUV radiation in the far field compared with a perfect ellipsoid shape.

Abstract: A lithographic apparatus comprising a projection system, and a liquid confinement structure configured to at least partly confine immersion liquid to an immersion space defined by the projection system, the liquid confinement structure and a substrate and/or substrate table is disclosed wherein a humid gas space is defined between the projection system, the liquid confinement structure and immersion liquid in the immersion space, the humid gas space being configured to contain humid gas.

Abstract: Methods are disclosed to create efficient model-based Sub-Resolution Assist Features (MB-SRAF). An SRAF guidance map is created, where each design target edge location votes for a given field point on whether a single-pixel SRAF placed on this field point would improve or degrade the aerial image over the process window. In one embodiment, the SRAF guidance map is used to determine SRAF placement rules and/or to fine-tune already-placed SRAFs. The SRAF guidance map can be used directly to place SRAFs in a mask layout. Mask layout data including SRAFs may be generated, wherein the SRAFs are placed according to the SRAF guidance map. The SRAF guidance map can comprise an image in which each pixel value indicates whether the pixel would contribute positively to edge behavior of features in the mask layout if the pixel is included as part of a sub-resolution assist feature.

Abstract: A lithographic apparatus includes an illumination system configured to condition a radiation beam and a support constructed to support a patterning device. The patterning device is configured to form a patterned radiation beam. A substrate table is constructed to hold a substrate, and a projection system is configured to project the patterned radiation beam onto a target portion of the substrate. The apparatus includes a heater arrangement that includes an electron beam generator configured to generate an electron beam, and an electron beam guide arrangement configured to guide the electron beam onto an optical element of the lithographic apparatus. The optical element forms a part of the illumination system or the projection system which, in use, is traversed by the radiation beam. The heater arrangement is controllable to provide a distribution of heat on the optical element by deflection of the electron beam.

Abstract: In a lithographic apparatus, a localized area of the substrate surface under a projection system is immersed in liquid. The height of a liquid supply system above the surface of the substrate can be varied using actuators. A control system uses feedforward or feedback control with input of the surface height of the substrate to maintain the liquid supply system at a predetermined height above the surface of the substrate.

Abstract: A scatterometer configured to measure a property of a substrate, includes a radiation source configured to provide a radiation beam; and a detector configured to detect a spectrum of the radiation beam reflected from a target (30) on the surface of the substrate (W) and to produce a measurement signal representative of the spectrum. The apparatus includes a beam shaper (51, 53) interposed in the radiation path between the radiation source and the detector, the beam shaper being configured to adjust the cross section of the beam dependent on the shape and/or size of the target.

Abstract: An apparatus and method to determine overlay of a target on a substrate (6) by measuring, in the pupil plane (40) of a high numerical aperture len (L1), an angle-resolved spectrum as a result of radiation being reflected off the substrate. The overlay is determined from the anti-symmetric component of the spectrum, which is formed by subtracting the measured spectrum and a mirror image of the measured spectrum. The measured spectrum may contain only zeroth order reflected radiation from the target.

Abstract: A substrate comprises a first mark and a second mark. The first mark comprises a first pattern with at least one mark feature formed by a first material and at least one further region formed by a second material. The first and second materials have different material characteristics with respect to a chemical-mechanical polishing process such that a step height in a direction substantially perpendicular to the surface of the substrate may be created by applying the chemical-mechanical polishing process. The second mark can be provided with a second step height by applying the chemical-mechanical polishing process. The second step height is substantially different from the first step height.

Abstract: In a lithographic apparatus, a localized area of the substrate surface under a projection system is immersed in liquid. The height of a liquid supply system above the surface of the substrate can be varied using actuators. A control system uses feedforward or feedback control with input of the surface height of the substrate to maintain the liquid supply system at a predetermined height above the surface of the substrate.

Abstract: An imprint lithography apparatus is disclosed that includes a support structure configured to hold an imprint template. The apparatus further includes an actuator located between the support structure and a side of the imprint template, when the imprint template is held by the support structure, configured to apply a force to the imprint template and a force sensor between the support structure and a side of the imprint template, when the imprint template is held by the support structure.

Abstract: A lithographic apparatus includes an illumination system configured to condition a radiation beam, a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, and a projection system configured to project the patterned radiation beam onto a target portion of the substrate. The projection system is mounted on a reference structure of the lithographic apparatus by a mount of the lithographic apparatus. The mount includes a first piezoelectric element to exert a force on the projection system, a second piezoelectric element to measure the force, and an interconnection member interposed between the first and second piezoelectric elements, the interconnection member comprising a cut.

Abstract: Embodiments of the invention related to lithographic apparatus and methods. A lithographic method comprises calculating a laser metric based on a spectrum of laser radiation emitted from a laser to a lithographic apparatus together with a representation of an aerial image of a pattern to be projected onto the substrate by the lithographic apparatus, and using the laser metric to modify operation of the laser or adjust the lithographic apparatus, and projecting the pattern onto the substrate.

Abstract: A lithographic apparatus operates by moving a substrate and a patterning device relative to each other in a sequence of movements such that a pattern is applied at a successive portions on the substrate. Each portion of the substrate is patterned by a scanning operation in which the patterning device is scanned through the radiation beam while synchronously scanning the substrate through the patterned radiation beam so as to apply the pattern to the desired portion on the substrate. An intrafield correction is applied during each scanning operation so as to compensate for distortion effects which vary during the scanning operation. The intrafield correction includes corrective variations of one or more properties of the projection system, and optionally out-of-plane movements of the patterning device and/or substrate table.

Abstract: Apparatus and methods are used to calibrate an array of individually controllable elements within a lithographic apparatus. A calibration unit can switch between a first state in which the modulated beam of radiation passes into a projection system for projecting the modulated beam of radiation onto a substrate and a second state in which a portion of the modulated beam of radiation is inspected by the calibration unit. The calibration unit generates calibration data, or alternatively, updates calibration data, based on the inspection of the modulated beam of radiation. An array controller uses the calibration data to provide control signals to elements of an array of individually controllable elements, which are subsequently configured in response to the control signals.