Abstract: A high harmonic generation assembly and method for generating high harmonic radiation. The assembly comprises a cavity configured to receive input radiation and increase the intensity of the input radiation inside the cavity for forming drive radiation suitable for use in high harmonic generation. The assembly further comprises an interaction region within the cavity at which, in use, a medium is present, the medium being configured to generate harmonic radiation by high harmonic generation when the drive radiation is incident thereupon, and an optical assembly configured to direct the drive radiation to pass through the interaction region, and comprising an output coupler comprising an aperture through which at least a part of the generated harmonic radiation is able to exit the cavity. The optical assembly is further configured to shape the drive radiation into a converging hollow beam before the drive radiation passes through the interaction region.

Abstract: An optical system delivers illuminating radiation and collects radiation after interaction with a target structure on a substrate. A measurement intensity profile is used to calculate a measurement of the property of the structure. The optical system may include a solid immersion lens. In a method, the optical system is controlled to obtain a first intensity profile using a first illumination profile and a second intensity profile using a second illumination profile. The profiles are used to derive a correction for mitigating the effect of, e.g., ghost reflections. Using, e.g., half-moon illumination profiles in different orientations, the method can measure ghost reflections even where a solid immersion lens would cause total internal reflection. The optical system may include a contaminant detection system to control a movement based on received scattered detection radiation. The optical system may include an optical component having a dielectric coating to enhance evanescent wave interaction.

Abstract: An alignment system, method and lithographic apparatus are provided for determining the position of an alignment mark, the alignment system comprising a first system configured to produce two overlapping images of the alignment mark that are rotated by around 180 degrees with respect to one another, and a second system configured to determine the position of the alignment mark from a spatial distribution of an intensity of the two overlapping images.

Abstract: An optical system delivers illuminating radiation and collects radiation after interaction with a target structure on a substrate. A measurement intensity profile is used to calculate a measurement of the property of the structure. The optical system may include a solid immersion lens. In a method, the optical system is controlled to obtain a first intensity profile using a first illumination profile and a second intensity profile using a second illumination profile. The profiles are used to derive a correction for mitigating the effect of, e.g., ghost reflections. Using, e.g., half-moon illumination profiles in different orientations, the method can measure ghost reflections even where a solid immersion lens would cause total internal reflection. The optical system may include a contaminant detection system to control a movement based on received scattered detection radiation. The optical system may include an optical component having a dielectric coating to enhance evanescent wave interaction.

Abstract: An alignment system, method and lithographic apparatus are provided for determining the position of an alignment mark, the alignment system comprising a first system configured to produce two overlapping images of the alignment mark that are rotated by around 180 degrees with respect to one another, and a second system configured to determine the position of the alignment mark from a spatial distribution of an intensity of the two overlapping images.

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: 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: 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.