A pattern measurement method includes forming a first pattern having a first size and a first brightness in a the first die area, forming a second pattern having a second size equal to the first size and a second brightness different from the first brightness in the first die area, obtaining a (1-1)-th measured size and a (1-1)-th measured brightness using a first measurement apparatus, and obtaining a (1-2)-th measured size and a (1-2)-th measured brightness using the first measurement apparatus, obtaining a (2-1)-th measured size and a (2-1)-th measured brightness using a second measurement apparatus, and obtaining a (2-2)-th measured size and a (2-2)-th measured brightness using the second measurement apparatus, and calibrating the first measurement apparatus and the second measurement apparatus based on first size correction data and first brightness correction data determined using the measured sizes and brightnesses.

A method of measuring an overlay or focus parameter from a target and associated metrology apparatus. The method includes configuring measurement radiation to obtain a configured measurement spectrum of the measurement radiation by: imposing an intensity weighting on individual wavelength bands of the measurement radiation such that the individual wavelength bands have an intensity according to the intensity weighting, the intensity weighting being such that a measured value for the overlay or focus parameter is at least partially corrected for the effect of target imperfections; and/or imposing a modulation on a measurement spectrum of the measurement radiation. The configured measurement radiation is used to measure the target. A value for the overlay or focus parameter is determined from scattered radiation resultant from measurement of the target.

An overlay metrology system may include an objective lens, illumination optics to illuminate an overlay target including a first grating with a first pitch on a first sample layer and a second grating with a second pitch on a second sample layer, where the first and second sample layers are separated by a layer separation distance greater than a depth of field of the objective lens. The system may further include collection optics with a radially-varying defocus distribution to compensate for the layer separation distance such that the first and second gratings are simultaneously in focus on the detector.

Methods and systems for determining one or more characteristics of light in an optical system are provided. One system includes a detector positioned in a path of light between a light source in the optical system and a specimen for which the optical system performs a process. The detector includes a center cut-out configured to allow only a first portion of the light from the light source to pass therethrough and four or more detector segments positioned around the center cut-out and in a path of only a second portion of the light from the light source. The four or more detector segments are configured to separately generate output responsive to the light incident thereon. The system also includes a control subsystem configured for determining one or more characteristics of the light from the light source based on the output separately generated by the four or more detector segments.

An overlay mark forming a Moire pattern, an overlay measurement method using the overlay mark, an overlay measurement apparatus using the overlay mark, and a manufacturing method of a semiconductor device using the overlay mark are provided. The overlay mark for measuring an overlay based on an image is configured to determine a relative misalignment between at least two pattern layers. The overlay mark includes a first overlay mark including a pair of first grating patterns which has a first pitch along a first direction and which is rotationally symmetrical by 180 degrees, and includes a second overlay mark including a pair of second grating patterns and a pair of third grating patterns. The second grating patterns partially overlap the first grating patterns and are rotationally symmetrical by 180 degrees, and the third grating patterns partially overlap the first grating patterns and are rotationally symmetrical by 180 degrees.

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.

An optical metrology tool may include one or more illumination sources to generate illumination having wavelengths both within a short-wave infrared (SWIR) spectral range and outside the SWIR spectral range, illumination optics configured to direct the illumination to a sample, a first imaging channel including a first detector configured to image the sample based on a first wavelength range including at least some wavelengths in the SWIR spectral range, a second imaging channel including a second detector configured to image the sample based on a second wavelength range including at least some wavelengths outside the SWIR spectral range, and a controller. The controller may receive first images of the sample from the first detector, receive second images of the sample from the second detector, and generate an optical metrology measurement of the sample based on the first and second images.

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.

Disclosed is a detection apparatus for simultaneous acquisition of multiple images of an object at a plurality of different focus levels; comprising: a modulator for obtaining multiple beam copies of an incoming beam; and a detector operable to capture said multiple beam copies, such that at two of said multiple beam copies are captured at different focus levels. Also disclosed is an inspection apparatus comprising such a detection system.