An apparatus includes a gas discharge system including a gas discharge chamber and configured to produce a light beam; and a spectral feature adjuster in optical communication with a pre-cursor light beam generated by the gas discharge chamber. The spectral feature adjuster includes: a body defining an interior that is held at a pressure below atmospheric pressure; at least one optical pathway defined between the gas discharge chamber and the interior of the body, the optical pathway being transparent to the pre-cursor light beam; and a set of optical elements within the interior, the optical elements configured to interact with the pre-cursor light beam.

A method is performed for scheduling a calibration relating to an optical device in a light source. The method can be performed by a calibration system including a calibration apparatus and a prediction controller. The method includes: receiving a property associated with the optical device while the optical device is being calibrated; calculating a current degradation metric based at least on the optical device property, the degradation metric modeling behavior of the optical device; estimating when a degradation of the optical device would exceed a threshold based on the current degradation metric; and scheduling a calibration of the optical device based at least in part on the estimate of optical device degradation.

A method and a device for characterizing the surface shape of an optical element. In the method, in at least one interferogram measurement carried out by an interferometric test arrangement, a test wave reflected at the optical element is caused to be superimposed with a reference wave not reflected at the optical element. In this case, the figure of the optical element is determined on the basis of at least two interferogram measurements using electromagnetic radiation having in each case linear input polarization or in each case circular input polarization, wherein the input polarizations for the two interferogram measurements differ from one another.

A measurement illumination optical unit guides illumination light into an object field of a projection exposure apparatus for EUV lithography. The illumination optical unit has a field facet mirror with a plurality of field facets and a pupil facet mirror with a plurality of pupil facets. The latter serve for overlaid imaging in the object field of field facet images of the field facets. A field facet imaging channel of the illumination light is guided via any one field facet and any one pupil facet. A field stop specifies a field boundary of an illumination field in the object plane. The illumination field has a greater extent along one field dimension than any one of the field facet images. At least some of the field facets include tilt actuators which help guide the illumination light into the illumination field via various field facets and one and the same pupil facet.

A method for measuring a surface shape of an optical element, wherein the optical element has a main body with a substrate and a reflective surface, and wherein at least one cooling channel for receiving a coolant is formed in the substrate, comprising: a) recording a cooling channel pressure, b) recording a measurement environment pressure, c) determining a pressure difference based on the cooling channel pressure and the measurement environment pressure, d) comparing the pressure difference with a predetermined target pressure difference, e) monitoring for a deviation between the pressure difference and the target pressure difference, wherein, if a deviation greater than a predetermined limit value is detected, the cooling channel pressure is adapted in such a way that the deviation becomes less than or equal to the predetermined limit value, and f) measuring the surface shape if the deviation is less than or equal to the predetermined limit value.

Provided in the disclosure is a photomask for detecting flare degree of lens of exposure machine table. The photomask includes a central exposure area and a peripheral area, exposure light of the exposure machine table passing through the lens and then penetrating the central exposure area to expose photoresist on a wafer, wherein the entire central exposure area is provided with a shading layer to prevent the exposure light from penetrating; and the peripheral area is provided with a plurality of light-transmitting stripes, and stray light formed after the exposure light passes through the lens penetrates the plurality of light-transmitting stripes to expose the photoresist. Further provided in the disclosure is a method for detecting flare degree of lens of exposure machine table by using the photomask. According to the disclosure, a lens flare problem of an exposure machine table can be found and solved in time.

Provided are a reticle defect inspection method and system. The reticle defect inspection method includes: a reticle is provided; a reticle defect inspection system is provided, and when the reticle is placed on a station or leaves the station, defect inspection is continuously performed on the reticle to obtain defect information of each defect; a dynamic threshold of each defect is obtained from the defect information of each defect; and whether the dynamic threshold of each defect belongs to a threshold unacceptable by the inspection system is judged, and if so, warning processing is performed.

According to one embodiment, a scanning light measuring apparatus includes a support table, a light-emission control circuit, a light-receiving element, a moving mechanism, and a measurement control circuit. An optical unit is placed on the support table. The optical unit has a synchronous detection sensor that forms scanning light and detects the scanning light. The light-emission control circuit controls the light-emission time of the scanning light. The light-receiving element receives the scanning light. The moving mechanism supports the light-receiving element so as to be movable in a main scanning direction and a rotation direction around an axis orthogonal to the main scanning direction and an optical axis direction of the scanning light. The measurement control circuit moves the light-receiving element in the main scanning direction by the moving mechanism, scans the light-receiving element with the scanning light, acquires an output of the light-receiving element, and measures a scanning light diameter.

A reticle inspection system and a method of handling a reticle in a reticle inspection system are provided. The reticle inspection system includes an active reticle carrier and an inspection tool. The reticle is disposed on the active reticle carrier, and the inspection tool is configured to determine an orientation of the reticle when the active reticle carrier is disposed on a reticle stage. The active reticle carrier is movable between a loading station and the reticle stage and is configured to rotate the reticle to reorient the reticle based on the orientation of the reticle while the active carrier is disposed on the reticle stage.

A method of inspecting a reticle includes obtaining a first image of a surface of the reticle at a first height by scanning the reticle surface with a light source at the first height of the reticle surface relative to a reference surface height of the reticle surface and obtaining a second image of the reticle surface at a second height by scanning the reticle surface with the light source at the second height of the reticle surface relative to the reference surface height of the reticle surface. The second height is different from the first height. The first and the second images are then combined to obtain a surface profile image of the reticle.