A metrology apparatus (302) includes a higher harmonic generation (HHG) radiation source for generating (310) EUV radiation. Operation of the HHG source is monitored using a wavefront sensor (420) which comprises an aperture array (424, 702) and an image sensor (426). A grating (706) disperses the radiation passing through each aperture so that the image detector captures positions and intensities of higher diffraction orders for different spectral components and different locations across the beam. In this way, the wavefront sensor can be arranged to measure a wavefront tilt for multiple harmonics at each location in said array. In one embodiment, the apertures are divided into two subsets (A) and (B), the gratings (706) of each subset having a different direction of dispersion. The spectrally resolved wavefront information (430) is used in feedback control (432) to stabilize operation of the HGG source, and/or to improve accuracy of metrology results.

An illumination adjustment apparatus, to adjust a cross slot illumination of a beam in a lithographic apparatus, includes a plurality of fingers to adjust the cross slot illumination to conform to a selected intensity profile. Each finger has a distal edge that includes at least two segments. The two segments form an indentation of the distal edge.

A method to determine a patterning process parameter, the method comprising: for a target, calculating a first value for an intermediate parameter from data obtained by illuminating the target with radiation comprising a central wavelength; for the target, calculating a second value for the intermediate parameter from data obtained by illuminating the target with radiation comprising two different central wavelengths; and calculating a combined measurement for the patterning process parameter based on the first and second values for the intermediate parameter.

The invention relates to a method and an apparatus for characterizing a microlithographic mask. In a method according to the invention, structures of a mask intended for use in a lithography process in a microlithographic projection exposure apparatus are illuminated by an illumination optical unit, wherein the mask is imaged onto a detector unit which has a plurality of pixels by an imaging optical unit. Here, a plurality of individual imaging processes are carried out with a pixel resolution specified by the detector unit, wherein these individual imaging processes differ from one another in respect of the position of at least one polarization-optical element situated in the imaging optical unit, wherein image data recorded by the detector unit are evaluated in an evaluation unit, wherein polarization-dependent effects on account of a polarization dependence of the interference of electromagnetic radiation that takes place in the wafer plane during the operation of the microlithographic projection exposure apparatus are emulated, wherein a conversion of the image data obtained in the individual imaging processes is implemented, in each case on the basis of at least one calibration image obtained by imaging a structure-free region of the mask onto the detector unit, wherein the calibration image respectively used is chosen differently depending on the position of the at least one polarization-optical element.

A metrology system may include a characterization tool configured to generate metrology data for a sample based on the interaction of an illumination beam with the sample, and may also include one or more adjustable measurement parameters to control the generation of metrology data. The metrology system may include one or more processors that may receive design data associated with a plurality of regions of interest for measurement, select individualized measurement parameters of the characterization tool for the plurality of regions of interest, and direct the characterization tool to characterize the plurality of regions of interest based on the individualized measurement parameters.

Method of determining a photodetector contribution to a measurement of apodization of a projection system of an immersion lithography apparatus, the method comprising providing a beam of radiation, illuminating an object with the beam of radiation, using the projection system to project an image of the object through a liquid layer and onto a photodetector, performing a first set of measurements of radiation intensity across a pupil plane of the projection system at a first liquid layer thickness, performing a second set of measurements of radiation intensity across the pupil plane of the projection system at a different liquid layer thickness, determining a set of intensity differences from the first set of measurements and the second set of measurements, comparing the determined set of intensity differences to an expected set of intensity difference, and using the results of the comparison to determine the photodetector contribution to a measurement of apodization.

Disclosed is a system and method for generating EUV radiation in which a laser is used in a multistage process to illuminate without altering a target material and then irradiate the target material to alter a target material with the illumination stage being used to determine the timing for firing during the irradiation stage or stages.

Correction information is acquired for compensating for a measurement error of a second encoder system that occurs due to a displacement between four sections of a scale member of the second encoder system, based on measurement information of the second encoder system obtained in a fifth area in which four heads of the second encoder system that are provided on a second stage, which holds a substrate, respectively face the four sections of the scale member.

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 recipe selection method includes obtaining measurements from metrology targets, metrology targets positioned on a semiconductor substrate, obtaining measurements from in-device targets, in-device targets positioned on the semiconductor substrate, and determining a recipe for accurate metrology using both metrology target measurements and in-device metrology measurements.