An apparatus for measuring a position of a mark on a substrate, the apparatus comprising: an illumination system configured to condition at least one radiation beam to form a plurality of illumination spots spatially distributed in series such that during scanning of the substrate the plurality of illumination spots are incident on the mark sequentially, and a projection system configured to project radiation diffracted by the mark from the substrate, the diffracted radiation being produced by diffraction of the plurality of illumination spots by the mark; wherein the projection system is further configured to modulate the diffracted radiation and project the modulated radiation onto a detecting system configured to produce signals corresponding to each of the plurality of illumination spots, the signals being combined to determine the position of the mark.

Disclosed is a method and associated apparatus for measuring a characteristic of interest relating to a structure on a substrate. The method comprises calculating a value for the characteristic of interest directly from the effect of the characteristic of interest on at least the phase of illuminating radiation when scattered by the structure, subsequent to illuminating said structure with said illuminating radiation.

According to the present disclosure, there is provided a device (2) and a method for measuring a wavelength for a laser device. The device (2) for measuring a wavelength for a laser device includes: a first optical path assembly and a second optical path assembly. The first optical path assembly and the second optical path assembly constitute a laser wavelength measurement optical path. The second optical path assembly includes: an FP etalon assembly (11) and an optical classifier (13). The homogenized laser beam passes through the FP etalon assembly (11) to generate an interference fringe. The optical classifier (13) is arranged after the FP etalon assembly (11) in the laser wavelength measurement optical path, and configured to deflect the laser beam passing through the FP etalon assembly (11). The FP etalon assembly (11) allows two FP etalons (FP1, FP2) to share the same optical path for an interference imaging, and therefore a compact structure having a small volume, a simple design, and a high stability are achieved. In cooperation with the optical classifier (13), a precise measurement for a laser wavelength may be achieved, and at the same time a wavelength measurement range is large. It is suitable for an online measurement for a laser wavelength and a corresponding closed-loop control feedback.

An inspection system (1600), a lithography apparatus, and an inspection method are provided. The inspection system (1600) includes an illumination system (1602), a detection system (1606), and processing circuitry (1622). The illumination system generates a first illumination beam (1610) at a first wavelength and a second illumination beam (1618) at a second wavelength. The first wavelength is different from the second wavelength. The illumination system irradiates an object (1612) simultaneously with the first illumination beam and the second illumination beam. The detection system receives radiation (1620) scattered by a particle (1624) present at a surface (1626) of the object at the first wavelength. The detection system generates a detection signal. The processing circuitry determines a characteristic of the particle based on the detection signal.

A method for inspecting an extreme ultraviolet (EUV) light source includes: removing a collector mirror of the EUV light source from a collector chamber; installing an inspection apparatus within the collector chamber, the apparatus including a selectively extendable and retractable member and a camera at one end of the member; operating a first actuator to extend the member along a path through the interior chamber of the EUV light source, thereby moving the camera to a given position within the interior chamber of the EUV light source; operating a second actuator to pan the camera about an axis of rotation, thereby establishing a given camera orientation within the interior of the EUV light source; and, capturing an image of the interior chamber of the EUV light source with the camera while the camera is at the given position and orientation established by the operation of the first and second actuators.

An apparatus for removing a residue of an EUV light source vessel including an internal side surface having a curved surface is provided. The apparatus includes a frame portion configured to be disposed on a bottom surface of an EUV light source vessel and a head portion above the frame portion. The head portion is configured to be rotatably moved on a circular trajectory while maintaining a desired (and/or alternatively predetermined) distance from the curved surface of the EUV light source vessel. The head portion may have a heating member configured to emit heat toward the curved surface of the EUV light source vessel. The heating member may have a shape curved in an arc corresponding to a portion of the circular trajectory.

A light source is provided capable of maintaining the temperature of a collector surface at or below a predetermined temperature. The light source in accordance with various embodiments of the present disclosure includes a processor, a droplet generator for generating a droplet to create extreme ultraviolet light, a collector for reflecting the extreme ultraviolet light into an intermediate focus point, a light generator for generating pre-pulse light and main pulse light, and a thermal image capture device for capturing a thermal image from a reflective surface of the collector.

An inspection system, a lithography apparatus, and an inspection method are provided. The inspection system includes an illumination system, a detection system, and processing circuitry. The illumination system generates a broadband beam and illuminates surface of an object with the broadband illumination beam. The broadband beam has a continuous spectral range. The detection system receives radiation scattered at the surface and by a structure near the surface. The detection system generates a detection signal based on an optical response to the broadband illumination beam. The processing circuitry analyzes the detection signal. The processing circuitry distinguishes between a spurious signal and a signal corresponding to a defect on the surface based on the analyzing The spurious signal is diminished for at least a portion of the continuous spectral range.

An apparatus for use in a metrology process or a lithographic process, the apparatus including: an object support module adapted to hold an object; and a first gas shower arranged on a first side of the object support module and adapted to emit a gas with a first velocity in a first gas direction which is a horizontal direction to cause a net gas flow in the apparatus to be a substantially horizontal gas flow in the first gas direction at least above the object support module.

A lithographic apparatus with a cover plate formed separately from a substrate table and means for stabilizing a temperature of the substrate table by controlling the temperature of the cover plate is disclosed. A lithographic apparatus with thermal insulation provided between a cover plate and a substrate table so that the cover plate acts as a thermal shield for the substrate table is disclosed. A lithographic apparatus comprising means to determine a substrate table distortion and improve position control of a substrate by reference to the substrate table distortion is disclosed.