Abstract: In one embodiment of the present invention, there is provided a gas gauge for use in a vacuum environment having a measurement gas flow channel. The gas gauge may comprise a measurement nozzle in the measurement gas flow channel. The measurement nozzle may be configured to operate at a sonically choked flow condition of a volumetric flow being sourced from a gas supply coupled to the measurement gas flow channel. The gas gauge may further comprise a pressure sensor operatively coupled to the measurement gas flow channel downstream from the sonically choked flow condition of the volumetric flow to measure a differential pressure of the volumetric flow for providing an indication of a gap between a distal end of the measurement nozzle and a target surface proximal thereto.

Abstract: A support such as a clamp (310) is configured to releasably hold a patterning device such as a reticle (300) to secure it and prevent heat-induced deformation of it. For example, an electrostatic clamp includes a first substrate (312) having opposing first (313) and second (315) surfaces, a plurality of burls (316) located on the first surface and configured to contact the reticle, a second substrate (314) having opposing first (317) and second (319) surfaces. The first surface of the second substrate is coupled to the second surface of the first substrate. A plurality of cooling elements (318) are located between the first surface of the second substrate and the second surface of the first substrate. The cooling elements are configured to cause electrons to travel from the second surface of the first substrate to the first surface of the second substrate. Each cooling element is substantially aligned with a respective burl.

Abstract: A system is disclosed for reducing overlay errors by controlling gas flow around a patterning device of a lithographic apparatus. The lithographic apparatus includes an illumination system configured to condition a radiation beam. The lithographic apparatus further includes a movable stage comprising a support structure that may be configured to support a patterning device. The patterning device may be configured to impart the radiation beam with a pattern in its cross-section to form a patterned radiation beam. In addition, the lithographic apparatus comprises a plate (410) positioned between the movable stage (401) and the projection system (208). The plate includes an opening (411) that comprises a first sidewall (411a) and a second sidewall (411b). The plate may be configured to provide a gas flow pattern (424) in a region between the movable stage and the projection system that is substantially perpendicular to an optical axis of the illumination system.

Abstract: A method for protecting a wet lens element from liquid degradation is provided. The method includes applying a thin coating of an organoxy-metallic compound to the side portions of a wet lens element to leave behind an optically inert, light absorbing metal oxide film. A liquid shield coating is applied on top of the metal oxide coating. The two coating layers protect the wet lens element from liquid degradation when the side portion of the wet lens element is submerged into a liquid. In an embodiment, the wet lens element is an immersion lithography wet lens element and the liquid is an immersion lithography liquid.

Abstract: A porous member is used in a liquid removal system of an immersion lithographic projection apparatus to smooth uneven flows. A pressure differential across the porous member may be maintained at below the bubble point of the porous member so that a single-phase liquid flow is obtained. Alternatively, the porous member may be used to reduce unevenness in a two-phase flow.

Abstract: A patterning device support (1100) for controlling a temperature of a patterning device (1102) can include a movable component (1104). The movable component can include a gas inlet (1108) for supplying a gas flow across a surface of the patterning device and a gas outlet (1110) for extracting the gas flow. The patterning device support can also include a gas flow generator (1118) coupled to a duct (1114, 1116) for recirculating the gas flow from the gas outlet to the gas inlet.

Abstract: A patterning device support (200), for example, a patterning device (202) or substrate support, can be configured to release internal stresses of a patterning device loaded thereon. The patterning device support can include a positive pressuring generating interface (206a, 206b) or an acoustic vibration generating interface (206a, 206b), or can be configured to oscillate while at least a portion of patterning device is decoupled from the patterning device support. A method of transferring a patterning device between a patterning device handling apparatus and a patterning device support configured to move the patterning device can include positioning the patterning device onto a surface of the patterning device support, and performing a process that releases internal stress of the patterning device.

Abstract: A lithographic method is disclosed that includes, on a substrate provided with a layer of a resist and a further layer of a material provided on the layer of resist, providing a pattern in the further layer, the pattern defining a space via which an area of the layer of resist may be exposed to radiation, a distance between features of the pattern defining the space, and exposing the layer of resist to radiation having a wavelength greater than the distance between features of the pattern defining the space, such that near-field radiation is generated which propagates into and exposes an area of the resist.

Abstract: A system (300) for supporting an exchangeable object (302) can include a movable structure (304) and an object holder (306) configured to be movable relative to the movable structure. The object holder can be configured to hold the exchangeable object. The system can also include a first actuator assembly (308) and second actuator assembly (316). The first actuator assembly can be configured to apply a force to the object holder to translate the exchangeable object generally along a plane. The second actuator assembly can be configured to apply a bending moment to the object holder. The exchangeable object can be a patterning device of a lithographic apparatus.

Abstract: A magnetic shield having non-magnetic gaps provides reduced magnetic cross-talk for a linear motor array in a precision positioning system. Redirecting the leakage flux limits the cross-talk and associated deleterious effects. Such preferred magnetic circuit paths for the leakage are affixed to the moving magnet system of the linear motor. Embodiments of the preferred flux leakage paths are realized by providing a ferromagnetic shield separated by a non-magnetic gap between the permanent magnets and the back-irons. In another embodiment, the ferromagnetic shield separation includes diamagnetic materials.

Abstract: A lithographic apparatus includes a uniformity correction system located at a plane and configured to receive a substantially constant pupil when illuminated with the beam of radiation. The uniformity correction system includes fingers that move into and out of intersection with a beam so as to correct an intensity of respective portions of the radiation beam. According to another embodiment, a method includes for: focusing a beam of radiation at a first plane to form pupil; adjusting the intensity of the beam near the first plane by moving fingers located near the first plane into and out of a path of the beam of radiation, wherein a width of a tip of each of the fingers is larger than that of corresponding actuating devices used to move each corresponding one of the fingers; patterning the beam; and projecting the patterned beam onto a substrate.

Abstract: A lithographic apparatus including a uniformity correction system is disclosed. The lithographic apparatus comprises an illumination system configured to condition a beam of radiation. The illumination system comprises a uniformity correction system located at a plane configured to receive a substantially constant pupil when illuminated with the beam of radiation. The uniformity correction system includes fingers configured to be movable into and out of intersection with a radiation beam so as to correct an intensity of respective portions of the radiation beam. A linear motor actuator arrangement drives the fingers to their respective appropriate positions to compensate for non-uniform illumination. Control is provided by a control system that precisely manipulates carriers of the fingers.

Abstract: A magnetic shield having non-magnetic gaps provides reduced magnetic cross-talk for a linear motor array in a precision positioning system. Redirecting the leakage flux limits the cross-talk and associated deleterious effects. Such preferred magnetic circuit paths for the leakage are affixed to the moving magnet system of the linear motor. Embodiments of the preferred flux leakage paths are realized by providing a ferromagnetic shield separated by a non-magnetic gap between the permanent magnets and the back-irons. In another embodiment, the ferromagnetic shield separation includes diamagnetic materials.

Abstract: Methods and systems are described for cleaning contamination from the surface of an object within a lithographic apparatus. A lithographic apparatus is provided that includes an illumination system configured to condition a radiation beam, a support constructed to hold a patterning device (302), the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, and a projection system configured to project the patterned radiation beam onto a target portion of the substrate. The lithographic apparatus further includes a cleaning system (500) for cleaning particles off of a surface of either the support or the patterning device. The cleaning system includes a cleaning surface (502) designed to contact the surface of either the support or the patterning device.

Abstract: A system for controlling temperature of a patterning device in a lithographic apparatus is discussed. The system includes a patterning device support configured to support a patterning device and a reticle cooling system configured to provide substantially uniform temperature distribution across the patterning device. The reticle cooling system includes a first and second array of gas inlets configured to provide a first and second gas flow along a first and second direction across a surface of the patterning device, respectively, where first and second directions are opposite to each other. The reticle cooling system further includes a switching control system configured to control operation of the first and second arrays of gas inlets.

Abstract: An apparatus to measure the position of a mark, the apparatus including an illumination arrangement to direct radiation across a pupil of the apparatus, the illumination arrangement including an illumination source to provide multiple-wavelength radiation of substantially equal polarization and a wave plate to alter the polarization of the radiation in dependency of the wavelength, such that radiation of different polarization is supplied; an objective to direct radiation on the mark using the radiation supplied by the illumination arrangement while scanning the radiation across the mark in a scanning direction; a radiation processing element to process radiation that is diffracted by the mark and received by the objective; and a detection arrangement to detect variation in an intensity of radiation output by the radiation processing element during the scanning and to calculate from the detected variation a position of the mark in at least a first direction of measurement.

Abstract: A system and method that bends a reticle and senses a curvature of a bent reticle in real-time. The system includes movable reticle stage, reticle vacuum clamps, sensor systems, and reticle bender. The reticle bender comprises piezo actuators. The sensor systems comprises measurement targets and corresponding sensors. The sensors are attached to the movable reticle stage and the measurement targets are attached to the reticle clamps, the reticle bender, or on reticle surfaces. The system is configured to determine a width of the reticle or distance between measurement targets at opposing ends of the reticle, measure a first rotational angle at a first end of the reticle, and measure a second local rotational angle at a second end of the reticle that is opposite to the first end. Based on the width or distance and the first and second angles, a field curvature of the reticle is determined.

Abstract: An apparatus to measure the position of a mark, the apparatus including an objective lens to direct radiation on a mark using radiation supplied by an illumination arrangement; an optical arrangement to receive radiation diffracted and specularly reflected by the mark, wherein the optical arrangement is configured to provide a first image and a second image, the first image being formed by coherently adding specularly reflected radiation and positive diffraction order radiation and the second image being formed by coherently adding specularly reflected radiation and negative diffraction order radiation; and a detection arrangement to detect variation in an intensity of radiation of the first and second images and to calculate a position of the mark in a direction of measurement therefrom.

Abstract: A porous member is used in a liquid removal system of an immersion lithographic projection apparatus to smooth uneven flows. A pressure differential across the porous member may be maintained at below the bubble point of the porous member so that a single-phase liquid flow is obtained. Alternatively, the porous member may be used to reduce unevenness in a two-phase flow.

Abstract: Systems and methods are disclosed for controlling the heating of a reticle. In one embodiment, a plurality of radiation sources generates a plurality of radiation beams (206) and delivers them to a patterning device (210) that absorbs a portion of the radiation from the beams and develops a spatially dependent heating profile. In a further embodiment, a plurality of resistive heating sources (906) generates heat in response to an applied voltage or current. The generated heat is absorbed by the patterning device from the resistive heating sources and leads to the development of a spatially dependent heating profile. Thermal stresses, strains, and deformations can be controlled by controlling the spatially dependent heating profile.