Disclosed is a method of metrology. The method comprises illuminating a radiation onto a substrate; obtaining measurement data relating to at least one measurement of each of one or more structures on the substrate; using a Fourier-related transform to transform the measurement data into a transformed measurement data; and extracting a feature of the substrate from the transformed measurement data, or eliminating an impact of a nuisance parameter.

A detection system for an alignment sensor, and an alignment sensor and lithographic projection apparatus comprising such a detection system is disclosed. The detection system comprises at least one detection circuit; and a plurality of optical fiber cores for transporting a measurement signal to the at least one detection circuit. At least as subset of the plurality of optical fiber cores are selectively switchable between a detection state and a non-detection state, thereby defining a configurable detection spot.

A detection system (200) includes an illumination system (210), a first optical system (232), a phase modulator (220), a lock-in detector (255), and a function generator (230). The illumination system is configured to transmit an illumination beam (218) along an illumination path. The first optical system is configured to transmit the illumination beam toward a diffraction target (204) on a substrate (202). The first optical system is further configured to transmit a signal beam including diffraction order sub-beams (222, 224, 226) that are diffracted by the diffraction target. The phase modulator is configured to modulate the illumination beam or the signal beam based on a reference signal. The lock-in detector is configured to collect the signal beam and to measure a characteristic of the diffraction target based on the signal beam and the reference signal. The function generator is configured to generate the reference signal for the phase modulator and the lock-in detector.

While a wafer stage moves linearly in a Y-axis direction, surface position information of a wafer surface at a plurality of detection points set at a predetermined interval in an X-axis direction is detected by a multipoint AF system, and by a plurality of alignment systems arranged in a line along the X-axis direction, marks at different positions on the wafer are each detected, and a part of a chipped shot of the wafer is exposed by a periphery edge exposure system. This allows throughput to be improved when compared with the case when detection operation of the marks, detection operation of the surface position information (focus information), and periphery edge exposure operation are performed independently.

Wafer alignment with restricted visual access has been disclosed. In an example, a method of processing a substrate for fabricating a solar cell involves supporting the substrate over a stage. The method involves forming a substantially opaque layer over the substrate. The substantially opaque layer at least partially covers edges of the substrate. The method involves performing fit-up of the substantially opaque layer to the substrate. The method involves illuminating the covered edges of the substrate with light transmitted through the stage, and capturing a first image of the covered edges of the substrate based on the light transmitted through the stage. The method further includes determining a first position of the substrate relative to the stage based on the first image of the covered edges. The substrate may be further processed based on the determined first position of the substrate under the substantially opaque layer.

An imprint apparatus for forming a pattern of an imprint material on a substrate using a mold having a mesa including a pattern region where a pattern and a mark are formed. The apparatus includes an alignment optical system which includes an illumination system configured to illuminate the mark with illumination light and a detecting system configured to detect an image of the mark illuminated by the illumination system. The illumination system includes a limiter configured to limit incidence of the illumination light to a side of the mesa, a ridge line of the mesa, and an outer region of the side.

A patterning device pre-alignment sensor system is disclosed. The system comprises at least one illumination source configured to provide an incident beam along a normal direction towards a patterning device. The system further comprises an object lens group channel along the normal direction configured to receive a 0th order refracted beam from the patterning device. The system further comprises a first light reflector configured to redirect the 0th order refracted beam to form a first retroreflected beam. The system further comprises a first image lens group channel configured to transmit the first retroreflected beam to a first light sensor. The first light sensor is configured to detect the first retroreflected beam to determine a location feature of the patterning device.

Disclosed is a substrate, associated patterning device and a method for measuring a position of the substrate. The method comprises performing an alignment scan of an alignment mark to obtain simultaneously: a first measurement signal detected in a first measurement channel and a second measurement signal detected in a second measurement channel. The first and second measurement signals are processed by subtracting a first direction component of the first measurement signal from a first direction component of the second measurement signal to obtain a first processed signal, the first direction components relating to said first direction. The position of an alignment mark is determined with respect to the first direction from the first processed signal.

A method of determining a position of a mark including a first pattern arranged in a first layer of a substrate and a second pattern arranged in a second layer of the substrate, includes determining information concerning the position of the mark as provisional position information based on an image of the mark, acquiring relative position information indicating a relative position between the first pattern and the second pattern, and determining the position of the mark based on the provisional position information and the relative position information.

A detection apparatus including a plurality of detection systems arranged spaced apart from each other so as to detect, of a plurality of marks provided on an object held by a stage, marks different from each other, and a processing unit configured to perform a first process of obtaining a first detection value by detecting the plurality of marks by one or more detection systems in a first state in which the stage is arranged at a first rotation angle, and a second process of obtaining a second detection value by detecting the plurality of marks by two or more detection systems in a second state in which the stage is arranged at a second rotation angle, and obtain a difference between the first detection value and the second detection value for each of the plurality of marks.