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.

Systems and methods that include providing for measuring a first topographical height of a substrate at a first coordinate on the substrate and measuring a second topographical height of the substrate at a second coordinate on the substrate are provided. The measured first and second topographical heights may be provided as a wafer map. An exposure process is then performed on the substrate using the wafer map. The exposure process can include using a first focal point when exposing the first coordinate on the substrate and using a second focal plane when exposing the second coordinate on the substrate. The first focal point is determined using the first topographical height and the second focal point is determined using the second topographical height.

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.

To uniformize the light intensity distribution on an irradiated surface in a light source device including a light-emitting diode (LED) array, a light source device includes a light-emitting diode (LED) array including a circuit having a substrate, a plurality of LED chips on the substrate, and a power supply. A predetermined plane is illuminated with light from the LED array. The plurality of LED chips includes first LED chips and second LED chips different from the first LED chips placed in a same column of the circuit, and the first LED chips have a placement angle different from a placement angle of the second LED chips.

The present invention provides an exposure apparatus that exposes a substrate via an original, including an illumination optical system configured to illuminate the original, and a projection optical system configured to project a pattern of the original onto the substrate, wherein the illumination optical system illuminates the original by illumination light which includes a first portion that enters an incident pupil of the projection optical system and a second portion which enters a region outside the incident pupil, and the first portion and the second portion are separated from each other on an incident pupil plane of the projection optical system.

Provided is a method of laser interference lithography, including: performing an interference exposure on a wafer coated with a photoresist; and performing a patterned flood exposure on the interference-exposed wafer, wherein the performing the flood exposure includes: determining a first light field distribution in the interference-exposed wafer; determining a light field distribution of the floodlight source as a second light field distribution based on the first light field distribution, an expected pattern distribution, and parameters of the floodlight source used for the flood exposure; and patterning the light field distribution of the floodlight source based on the second light field distribution, and controlling the floodlight source having the patterned light field distribution to perform the flood exposure on the interference-exposed wafer, so as to form the expected pattern distribution in the flood-exposed wafer.

In corner sections of first to fourth quadrants whose origin point is a center of an upper surface of a stage, three each of two-dimensional heads are provided. The three each of two-dimensional heads include one first head and two second heads. The stage is driven, while measuring a position of the stage using three first heads that face a two-dimensional grating of a scale plate provided above the stage from the four first heads, and during the driving, difference data of measurement values of the two second heads with respect to the first head in a measurement direction are taken in for head groups to which the three first heads belong, respectively, and using the difference data, grid errors are calibrated.

Embodiments of the present disclosure include measurement systems and grating pattern arrays. The measurement systems include multiple subsystems for creating diffraction patterns or magnified real images of grating regions on a substrate. The measurements systems are configured to reflect and transmit light, and the reflected and transmitted beams create diffraction patterns and enlarged images. The diffraction patterns and images provide information on grating pitch and angles of grating regions. Grating pattern arrays disposed on a substrate include main regions and reference regions. The reference regions are used to locate corresponding main regions. The measurement systems do not include a rotating stage, and thus precise control of rotation of a stage is not needed.

A light irradiation method includes splitting light from a coherent light source, which outputs the light at a wavelength equal to or less than 300 nm, into a plurality of branch beams. A wavefront of the light is shaped before splitting the light. The light irradiation method also includes causing the branch beams to intersect at an interference angle equal to or less than 20 to generate interfered light, and irradiating a substrate with the interfered light while continuously conveying the substrate relative to the interfered light.

In corner sections of first to fourth quadrants whose origin point is a center of an upper surface of a stage, three each of two-dimensional heads are provided. The three each of two-dimensional heads include one first head and two second heads. The stage is driven, while measuring a position of the stage using three first heads that face a two-dimensional grating of a scale plate provided above the stage from the four first heads, and during the driving, difference data of measurement values of the two second heads with respect to the first head in a measurement direction are taken in for head groups to which the three first heads belong, respectively, and using the difference data, grid errors are calibrated.