A metrology system includes a radiation source (708), a phased array (722a,b;724a,b;726;734), a detector, and a comparator. The phased array includes optical elements (706), waveguides (704), and phase modulators (702). The phased array generates a beam of radiation and directs the beam toward a surface of an object. The optical elements radiate radiation waves. The waveguides guide radiation from the radiation source to the optical elements. The phase modulators adjust phases of the radiation waves such that the radiation waves combine to form the beam. The detector receives radiation scattered from the surface and generates a detection signal based on the received radiation. The comparator analyzes the detection signal and determines a location of a defect on the surface based on the analyzing.

Metrology is performed on a semiconductor wafer using a system with an apodizer. A spot is formed on the semiconductor wafer with a diameter from 2 nm to 5 nm. The associated beam of light has a wavelength from 400 nm to 800 nm. Small target measurement can be performed at a range of optical wavelengths.

An overlay metrology system may include illumination sources configured to generate one or more pairs of mutually coherent illumination beams and illumination optics to direct the pairs of illumination beams to an overlay target at common altitude incidence angles and symmetrically opposed azimuthal incidence angles, where the overlay target includes two or more grating structures distributed along one or more measurement directions. The system may further include imaging optics to image the overlay target onto detectors when implementing the metrology recipe, where an image of a particular one of the two or more grating structures includes a sinusoidal interference pattern generated exclusively with a single non-zero diffraction order of light from each of the illumination beams within the particular one of the pairs of illumination beams. The system may further include a controller to determine overlay measurements based on images of the overlay target.

An optical element, and a metrology tool or system employing the optical element for measurements of structures on a substrate. The optical element includes a first portion configured to reflect the light received from an illumination source towards the substrate, and a second portion configured to transmit the light redirected from the substrate or a desired location, the first portion having a higher coefficient of reflectivity than the second portion, and the second portion having a higher coefficient of transmissivity than the first portion. A metrology tool may include the optical elements and a sensor configured to receive a diffraction pattern caused by radiation redirected from a substrate, and a processor configured to receive a signal relating to the diffraction pattern from the sensor, and determine overlay associated with the substrate by analyzing the signal.

A method may include receiving time-varying interference signals from two or more photodetectors associated with a grating structure and a reference grating structure. The grating structure may include one or more diffraction gratings, where the reference grating structure includes a reference grating arranged next to the one or more diffraction gratings of the grating structure and where the one or more illumination beams simultaneously interact with grating structure and the reference grating structure as the sample is scanned relative to the illumination beam. The method may include determining at least one of a real-time position or a scanning velocity of the grating structure during the scan based on the reference grating signal. The method may include determining one or more overlay errors based on the grating signals from the grating structure and the real-time position of the grating structure during the scan determined based on the reference grating signal.

Measurement apparatus for the inspection of photomasks, comprising an EUV radiation source, an illumination system, a projection lens and an EUV image sensor. EUV radiation emitted by the EUV radiation source is guided via the illumination system to a photomask. EUV radiation reflected at the photomask is guided via the projection lens to the EUV image sensor such that the photomask is imaged on the EUV image sensor. A pellicle is arranged between the EUV radiation source and the illumination system, with the result that the EUV radiation passes through the pellicle between the EUV radiation source and the illumination system. The invention also relates to a method for inspecting photomasks.

Disclosed is a metrology device operable to measure a sample with measurement radiation and associated method. The metrology device comprises: an illumination branch operable to propagate measurement radiation to a sample, a detection branch operable to propagate one or more components of scattered radiation, scattered from said sample as a result of illumination of the sample by said measurement radiation; and a dispersive arrangement in either of said illumination branch or said detection branch. The dispersive arrangement is arranged to maintain one or more components of said scattered radiation at substantially a same respective location in a detection pupil plane over a range of wavelength values for said measurement radiation.

Disclosed is a dark-field interferometric microscope and associated microscopy method. The microscope comprises an object branch being operable to propagate object radiation onto a sample and collect resultant scattered radiation from said sample and a reference branch being operable to propagate reference radiation. The object radiation and said reference radiation are mutually pointwise spatially coherent. A filter arrangement removes a zeroth order component from said scattered radiation to provide filtered scattered radiation; and a detection arrangement detects an interferometric image from interference of said filtered scattered radiation and reference radiation.

When simulating illumination and imaging properties of an optical production system when illuminating and imaging an object by use of an optical measurement system of a metrology system, the optical measurement system having an illumination optical unit for illuminating the object and a pupil stop, in particular a displaceable pupil stop, and having an imaging optical unit for imaging the object into an image plane is initially provided. When simulating the properties of the optical production system with the optical measurement system, a plurality of pupil stops are initially provided. Measurement aerial images are then recorded by use of the plurality of pupil stops. A complex mask transfer function is reconstructed from the recorded measurement aerial images and a 3-D aerial image is determined from this function and the illumination setting of the optical production system. This yields an improved simulation method.

A method of correcting a metrology image for an out-of-band leakage signal contribution resultant from leakage of measurement radiation at suppressed wavelengths. The method includes: obtaining at least one correction image, the correction image obtained using measurement radiation with all wavelengths or wavelength bands maximally suppressed by a radiation modulation device; obtaining a metrology image using measurement radiation including modulated broadband radiation, modulated by the radiation modulation device to obtain a configured spectrum; and using the at least one correction image to correct the metrology image.