The invention relates to a method for determining the thickness of a contaminating layer and/or the type of a contaminating material on a surface (7) in an optical system, in particular on a surface (7) in an EUV lithography system, comprising: irradiating the surface (7) on which plasmonic nanoparticles (8a,b) are formed with measurement radiation (10), detecting the measurement radiation (10a) scattered at the plasmonic nanoparticles (8a,b), and determining the thickness of the contaminating layer and/or the type of the contaminating material on the basis of the detected measurement radiation (10a). The invention also relates to an optical element (1) for reflecting EUV radiation (4), and to an EUV lithography system.

A method of cleaning a collector of an extreme ultraviolet light source system includes introducing the collector separated from the extreme ultraviolet light source system into a chamber; capturing an optical image of a reflective surface of the collector; measuring a contamination level of the reflective surface by comparing the optical image with a prestored standard image; performing a first cleaning operation if the contamination level exceeds a preset first reference value, the first cleaning operation including cleaning the reflective surface by spraying dry ice particles onto the reflective surface; and performing a second cleaning operation if the contamination level is less than or equal to the preset first reference value. The second cleaning operation includes cleaning the reflective surface by radiating atmospheric plasma onto the reflective surface and measuring a microcontamination level and a damage level of the reflective surface.

An extreme ultraviolet (EUV) collector inspection apparatus and method capable of precisely inspecting a contamination state of an EUV collector and EUV reflectance in accordance with the contamination state are provided. The EUV collector inspection apparatus includes a light source arranged in front of an EUV collector to be inspected and configured to output light in a visible light (VIS) band from UV rays, an optical device configured to output narrowband light from the light, and a camera configured to perform imaging from an UV band to a VIS band. An image by wavelength of the EUV collector is obtained by using the optical device and the camera and a contamination state of the EUV collector is inspected.

A mask (M) for EUV lithography includes: a substrate (7), a first surface region (A.sub.1) formed by a surface (8a) of a multilayer coating (8) embodied to reflect EUV radiation (27), said surface (8a) facing away from the substrate (7), and a second surface region (A.sub.2) formed by a surface (18a) of a further coating (18) embodied to reflect DUV radiation (28) and to suppress the reflection of EUV radiation (27), said surface (18a) facing away from the substrate (7). The further coating is a multilayer coating (18). Also disclosed are an EUV lithography apparatus that includes such a mask (M) and a method for determining a contrast proportion caused by DUV radiation when imaging a mask (M) onto a light-sensitive layer.

A projection exposure system (10) for microlithography. The system includes projection optics (12) configured to image mask structures into a substrate plane (16), an input diffraction element (28) which is configured to convert irradiated measurement radiation (21) into at least two test waves (30) directed onto the projection optics (12) with differing propagation directions, a detection diffraction element (34; 28) which is disposed in the optical path of the test waves (30) after the latter have passed through the projection optics (12) and is configured to produce a detection beam (36) from the test waves (30) which has a mixture of radiation portions of both test waves (30), a photo detector (38) disposed in the optical path of the detection beam (36) which is configured to record the radiation intensity of the detection beam (36), time resolved, and an evaluation unit which is configured to determine the lateral imaging stability of the projection optics (12) from the radiation intensity recorded.

The present disclosure relates to a method and apparatus for mitigating printable native defects in an extreme ultra violet (EUV) mask substrate. In some embodiments, the method is performed by identifying a printable native defect within an EUV mask substrate that violates one or more sizing thresholds. A first section of the EUV mask substrate including the printable native defect is removed to form a concavity within the EUV mask substrate. A multi-layer replacement section that is devoid of a printable native defect is inserted into the concavity.

A method of controlling a feedback system with a data matching module of an extreme ultraviolet (EUV) radiation source is disclosed. The method includes obtaining a slit integrated energy (SLIE) sensor data and diffractive optical elements (DOE) data. The method performs a data match, by the data matching module, of a time difference of the SLIE sensor data and the DOE data to identify a mismatched set of the SLIE sensor data and the DOE data. The method also determines whether the time difference of the SLIE sensor data and the DOE data of the mismatched set is within an acceptable range. Based on the determination, the method automatically validates a configurable data of the mismatched set such that the SLIE sensor data of the mismatched set is valid for a reflectivity calculation.

A device and a method for characterizing the surface shape of a test object. The device for characterizing the surface shape of a test object has a test arrangement (130, 230) for determining the surface shape of a test object (111, 112, 113, 211, 212, 213) using a test wave. The test wave has a wavefront generated by diffraction at a diffractive optical element. The device additionally has a first vacuum chamber (110, 210) and a second vacuum chamber (120, 220), wherein the second vacuum chamber (120, 220) has a magazine for mounting at least two diffractive optical elements (121, 122, 123, 221, 222, 223).

A lithographic apparatus includes an illumination system to produce a beam of radiation, a support to support a patterning device to impart a pattern on the beam, a projection system to project the patterned beam onto a substrate, and a metrology system that includes a radiation source to generate radiation, an optical element to direct the radiation toward a target, a detector to receive a first and second radiation scattered by the target and produce a first and second measurement respectively based on the received first and second radiation, and a controller. The controller determines a correction for the first measurement, an error between the correction for the first measurement and the first measurement, and a correction for the second measurement based on the correction for the first measurement, the second measurement, and the error. The lithographic apparatus uses the correction to adjust a position of a substrate.

A lithographic apparatus includes an illumination system to produce a beam of radiation, a support to support a patterning device to impart a pattern on the beam, a projection system to project the patterned beam onto a substrate, and a metrology system that includes a radiation source to generate radiation, an optical element to direct the radiation toward a target, a detector to receive a first and second radiation scattered by the target and produce a first and second measurement respectively based on the received first and second radiation, and a controller. The controller determines a correction for the first measurement, an error between the correction for the first measurement and the first measurement, and a correction for the second measurement based on the correction for the first measurement, the second measurement, and the error. The lithographic apparatus uses the correction to adjust a position of a substrate.