A method to improve a lithographic process for imaging a portion of a patterning device pattern onto a substrate using a lithographic projection having an illumination system and projection optics, the method including: (1) obtaining a simulation model that models projection of radiation by the projection optics, wherein the simulation model models an effect of an obscuration in the projection optics, and configuring, based on the model, the portion of the patterning device pattern, and/or (2) obtaining a simulation model that models projection of radiation by the projection optics, wherein the simulation model models an anamorphic demagnification of radiation by the projection optics, and configuring, based on the model, the portion of the patterning device pattern taking into account an anamorphic manufacturing rule or anamorphic manufacturing rule ratio.

A method of calibrating a projection system heating model to predict an aberration in a projection system in a lithographic apparatus, the method comprising passing exposure radiation through a projection system to expose one or more exposure fields on a substrate provided on a substrate table, making measurements of the aberration in the projection system caused by the exposure radiation, wherein the time period between measurements is less than the time period that would be taken to expose all exposure fields on the substrate.

A method for determining a characteristic of a feature in an object, the feature being disposed below a surface of the object is disclosed. The surface of the object is irradiated with a pulsed pump radiation beam so as to produce an acoustic wave in the object. The surface of the object is then irradiated with a measurement radiation beam. A portion of the measurement radiation beam scattered from the surface is received and a characteristic of the feature in the object is determined from at least a portion of the measurement radiation beam scattered from the surface within a measurement time period. A temporal intensity distribution of the pulsed pump radiation beam is selected such that in the measurement time period a signal to background ratio is greater than a signal to background ratio achieved using a single pulse of the pulsed pump radiation beam. The signal to background ratio is a ratio of: (a) signals generated at the surface by reflections of acoustic waves from the feature to (b) background signals generated at the surface by reflections of acoustic waves which have not reflected from the feature.

A method for restoring an illumination system installed in an EUV apparatus is provided.

An inspection apparatus (140) measures asymmetry or other property of target structures (T) formed by a lithographic process on a substrate. For a given set of illumination conditions, accuracy of said measurement is influenced strongly by process variations across the substrate and/or between substrates. The apparatus is arranged to collect radiation scattered by a plurality of structures under two or more variants of said illumination conditions (p1−, p1, p1+; λ1−, λ1, λ1+). A processing system (PU) is arranged to derive the measurement of said property using radiation collected under a different selection or combination of said variants for different ones of said structures. The variants may be for example in wavelength, or in angular distribution, or in any characteristic of the illumination conditions. Selection and/or combination of variants is made with reference to a signal quality (302, Q, A) observed in the different variants.

A method comprising determining aberrations caused by each lithographic apparatus of a set of lithographic apparatuses, calculating adjustments of the lithographic apparatuses which minimize differences between the aberrations caused by each of the lithographic apparatuses, and applying the adjustments to the lithographic apparatuses, providing better matching between the aberrations of patterns projected by the lithographic apparatuses.

An image reading device includes light guides (5, 6) that emit light to an object to be read, a lens body (8) that condenses reflected light, a light receiver (13) that receives the reflected light, a sensor board (24) on which is mounted the light receiver (13), a lens holder (11), and a housing (9) that houses or holds these components. The lens holder (11) includes a holder bottom (11g), light guide positioners (11a, 11b) and lens body holders (11e, 11f). In the lens holder (11), the lens body (8) is attached between the lens body holders (11e, 11f), the sensor board (24) is attached to the holder bottom (11g) such that the light receiver (13) aligns with an optical axis of the lens body (8), and the light guides (5, 6) are attached to the light guide positioners (11a, 11b). A surface of each light guide positioner (11a, 11b) that faces the corresponding light guide (5, 6) to be attached has at least a portion having a same shape a s a shape of a surface of the light guide.

An image reading device (100) includes a lens array (4), a light receiver (6), and at least one light blocking member. The lens array (4) includes first lens bodies arranged in a line in a main scanning direction with predetermined spacing therebetween to converge light from a reading target. The light receiver (6) receives light converged by each first lens body. The at least one light blocking member is disposed between the light receiver (6) and an end of the lens array (4) proximate to the reading target at at least one position corresponding to the predetermined spacing in the main scanning direction. The at least one light blocking member blocks light from the reading target propagating between the first lens bodies, and each of the at least one light blocking member separates optical paths of light converged by ones of the first lens bodies adjacent to each other.

A system comprises a plurality of laser generators, each generating a coherent beam, the plurality of laser generators arranged such that at least two of the generated coherent beams intersect with each other. The system further comprises an anti-refraction prism. The anti-refraction prism has a plurality of incident surfaces. The anti-refraction prism also has an egress surface facing a photosensitive film layer, with the coherent beams interfering within the anti-refraction prism and exiting at the egress surface to create an interference exposure pattern at an exposure region of the photosensitive film layer. Furthermore, the anti-refraction prism has a refraction index within a threshold range of the refraction index of the photosensitive film layer, and wherein the anti-refraction prism reduces a change in angle of each coherent beam in the photosensitive film layer due to refraction.

A method includes generating a plasma that emits a first EUV radiation in a vessel at a first gas exhaust rate of the vessel; directing the first EUV radiation to a first substrate using a collector in the vessel; halting the generating of the first EUV radiation; and ejecting a gas past the collector at a second gas exhaust rate of the vessel, in which the second gas exhaust rate is greater than the first gas exhaust rate after the halting.