Abstract: An alignment method includes directing an illumination beam with a varying wavelength or frequency towards an alignment target, collecting diffraction beams from the alignment target and directing towards an interferometer. The alignment method also includes producing, by the interferometer, two diffraction sub-beams from the diffraction beams, wherein the diffraction sub-beams are orthogonally polarized, rotated 180 degrees with respect to each other around an alignment axis, and spatially overlapped. The alignment method further includes measuring interference intensity of the diffraction beams based on a temporal phase shift, wherein the temporal phase shift is a function of the varying wavelength or frequency of the illumination beam and a fixed optical path difference between the diffraction beams. The alignment method also includes determining a position of the alignment target from the measured interference intensity.

Abstract: A substrate holder, for a lithographic apparatus, having a main body, a plurality of support elements to support a substrate and a seal unit. The seal unit may include a first seal positioned outward of and surrounding the plurality of support elements. A position of a substrate contact region of an upper surface of the first seal may be arranged at a distance from the plurality of support elements sufficient enough such that during the loading/unloading of the substrate, a force applied to the first seal by the substrate is greater than a force applied to the plurality of support elements by the substrate. A profile of the contact region, in a cross section through the seal, may have a shape which is configured such that during the loading/unloading of the substrate, the substrate contacts the seal via at least two different points of the profile.

Abstract: An apparatus for and method of sensing alignment marks in which a self-referencing interferometer based sensor outputs standing images of the alignment marks and camera device is used to capture the images as output by the sensor and a detector is used to obtain phase information about the alignment marks from the images as output by the sensor.

Abstract: A method of determining an overlay measurement associated with a substrate and a system to obtain an overlay measurement associated with a patterning process. A method for determining an overlay measurement may be used in a lithography patterning process. The method includes generating a diffraction signal by illuminating a first overlay pattern and a second overlay pattern using a coherent beam. The method also includes obtaining an interference pattern based on the diffraction signal. The method further includes determining an overlay measurement between the first overlay pattern and the second overlay pattern based on the interference pattern.

Abstract: A sensor apparatus includes a sensor chip, an illumination system, a first optical system, a second optical system, and a detector system. The illumination system is coupled to the sensor chip and transmits an illumination beam along an illumination path. The first optical system is coupled to the sensor chip and includes a first integrated optic to configure and transmit the illumination beam toward a diffraction target on a substrate, disposed adjacent to the sensor chip, and generate a signal beam including diffraction order sub-beams generated from the diffraction target. The second optical system is coupled to the sensor chip and includes a second integrated optic to collect and transmit the signal beam from a first side to a second side of the sensor chip. The detector system is configured to measure a characteristic of the diffraction target based on the signal beam transmitted by the second optical system.

Abstract: A sensor apparatus includes an illumination system, a detector system, and a processor. The illumination system is con-figured to transmit an illumination beam along an illumination path and includes an adjustable optic. The adjustable optic is configured to transmit the illumination beam toward a diffraction target on a substrate that is disposed adjacent to the illumination system. The transmitting generates a fringe pattern on the diffraction target. A signal beam includes diffraction order sub-beams that are diffracted by the diffraction target. The detector system is configured to collect the signal beam. The processor is configured to measure a char-acteristic of the diffraction target based on the signal beam. The adjustable optic is configured to adjust an angle of incidence of the illumination beam on the diffraction target to adjust a periodicity of the fringe pattern to match a periodicity of the diffraction target.

Abstract: A mode control system and method for controlling an output mode of a broadband radiation source including a photonic crystal fiber (PCF). The mode control system includes at least one detection unit configured to measure one or more parameters of radiation emitted from the broadband radiation source to generate measurement data, and a processing unit configured to evaluate mode purity of the radiation emitted from the broadband radiation source, from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimization of one or more pump coupling conditions of the broadband radiation source. The one or more pump coupling conditions relate to the coupling of a pump laser beam with respect to a fiber core of the photonic crystal fiber.

Abstract: A system designed to couple a patterning device to a support structure having a plurality of burls includes a camera module, an actuator, and a controller. The camera module is designed to capture image data of a backside of the patterning device. The actuator is coupled to at least one burl of the plurality of burls and is designed to move the at least one burl. The controller is designed to receive the image data captured from the camera module and determine one or more locations of contamination on the backside of the patterning device from the image data. The controller is also designed to control the actuator to move the at least one burl of the plurality of burls away from the one or more locations of contamination on the backside of the patterning device, based on the determined locations of contamination.

Abstract: A method of forming an anti-reflection layer, the method including applying a first mixture to an object, the first mixture made from a combination of aluminum tri-sec-butoxide (ATSB), a first chelating agent, water and an alcohol; removing a majority of the alcohol from the applied first mixture; after the removing, applying a second mixture to the object, the second mixture made from a combination of aluminum tri-sec-butoxide, a second chelating agent different than the first chelating agent, water and an alcohol; and removing a majority of the alcohol from the applied second mixture, wherein the applied first and second mixtures are used to form the anti-reflection layer.

Abstract: A patterning device for patterning product structures onto a substrate and an associated substrate patterned using such a patterning device. The patterning device includes target patterning elements for patterning at least one target from which a parameter of interest can be inferred. The patterning device includes product patterning elements for patterning the product structures. The target patterning elements and product patterning elements are configured such that the at least one target has at least one boundary which is neither parallel nor perpendicular with respect to the product structures on the substrate.

Abstract: An optical assembly and a method of making an optical assembly in which additive manufacturing techniques are used to form a support structure either directly on an optical element or on a carrier that is subsequently bonded to an optical element.

Abstract: An electrostatic clamp and a method for fabricating the same. The electrostatic clamp includes a first stack and a second stack, wherein the first stack is joined with the second stack. Each of the first and second stacks includes a clamp body, one or more electrodes disposed on the clamp body, a dielectric plate disposed on the electrodes, and a plurality of channels inside the clamp body.

Abstract: A self-referencing interferometer (SRI) system for an alignment sensor apparatus includes a first prism and a second prism. The first prism has an input surface for an incident beam. The second prism is coupled to the first prism and has an output surface for a recombined beam. The recombined beam includes a first image and a second image rotated by 180 degrees with respect to the first image. The first and second prisms are identical in shape. A dual self-referencing interferometer (DSRI) system for an alignment sensor apparatus includes a first prism assembly having an input surface for a first incident beam and a second incident beam, and a second prism assembly coupled to the first prism assembly and having an output surface for a first recombined beam and a second recombined beam. The first and second prism assemblies are identical in shape.

Abstract: An illumination adjustment apparatus, to adjust a cross slot illumination of a beam in a lithographic apparatus, includes a plurality of fingers to adjust the cross slot illumination to conform to a selected intensity profile. Each finger has a distal edge that includes at least two segments. The two segments form an indentation of the distal edge.

Abstract: A method of fabricating a substrate table includes supporting a table base and disposing a coating on a surface of the table base. The surface of the table base is substantially flat. The coating has a non-uniform thickness. The coating exerts a stress on the table so as to bend the table base. The non-uniform thickness causes a surface of the coating to become substantially flat after the bending.

Abstract: A reticle transport system having a magnetically levitated transportation stage is disclosed. Such a system may be suitable for use in vacuum environments, for example, ultra-clean vacuum environments.

Abstract: A mode control system and method for controlling an output mode of a broadband radiation source including a photonic crystal fiber (PCF). The mode control system includes at least one detection unit configured to measure one or more parameters of radiation emitted from the broadband radiation source to generate measurement data, and a processing unit configured to evaluate mode purity of the radiation emitted from the broadband radiation source, from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimization of one or more pump coupling conditions of the broadband radiation source. The one or more pump coupling conditions relate to the coupling of a pump laser beam with respect to a fiber core of the photonic crystal fiber.

Abstract: A method to reduce sensitivity of a level sensor, arranged to measure a height of a substrate, to variations of a property of an optical component in the level sensor includes directing a beam of radiation toward a diffractive element and directing the beam, via an optical system, to a first reflective element at a first angle of incidence. The beam has a first polarization and a second polarization that is perpendicular to the first polarization. The first reflective element reflects the beam toward a second reflective element at a second angle of incidence causing the beam to impinge on the substrate. The first and second angles of incidence are selected to reduce variations of a ratio of intensities of the first polarization to the second polarization of the beam imparted by a property of a layer of at least one of the first and second reflective elements.

Abstract: Apparatus for, and method of, measuring a parameter of an alignment mark on a substrate in which an optical system is arranged to receive at least one diffraction order from the alignment mark and the diffraction order is modulated at a pupil or a wafer conjugate plane of the optical system, a solid state optical device is arranged to receive the modulated diffraction order, and a spectrometer is arranged to receive the modulated diffraction order from the solid state optical device and to determine an intensity of one or more spectral components in the modulated diffraction order.

Abstract: A pellicle suitable for use with a patterning device for a lithographic apparatus. The pellicle comprising at least one breakage region which is configured to preferentially break, during normal use in a lithographic apparatus, prior to breakage of remaining regions of the pellicle. At least one breakage region comprises a region of the pellicle which has a reduced thickness when compared to surrounding regions of the pellicle.