Abstract: Scatterometers making use of a Glan-laser polarizer are described. The use of Glan-laser polarizers as described generally results in an improved extinction ratio and use over a greater range of wavelengths when compared with dielectric polarizers.

Abstract: An inspection apparatus configured to measure a property of a substrate includes an illumination source, a beam splitter, a first polarizer positioned between the illumination source and the beam splitter, an objective lens and an optical device that alters a polarization state of radiation traveling through it positioned between the beam splitter and the substrate and a second polarizer positioned between the beam splitter and a detector. An axis of the second polarizer is rotated with respect to an axis of the first polarizer. Radiation polarized by the first polarizer that reflects off any optical elements between the beam splitter and the optical device is prevented from entering the detector by the second polarizer. Only radiation that passes twice through the optical device has its polarization direction rotated so that it passes through the second polarizer and enters the detector.

Abstract: The simultaneous measurement of four separately polarized beams upon diffraction from a substrate is used to determine properties of the substrate. Circularly or elliptically polarized light sources are passed via up to three polarizing elements. This polarizes the light sources by 0, 45, 90 and 135°. The plurality of polarizing beamsplitters replaces the use of a phase modulator, but enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate.

Abstract: The simultaneous measurement of four separately polarized beams upon diffraction from a substrate is used to determine properties of the substrate. Circularly or elliptically polarized light sources are passed via up to three polarizing elements. This polarizes the light sources by 0, 45, 90 and 135°. The plurality of polarizing beamsplitters replaces the use of a phase modulator, but enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate.

Abstract: The present invention refers to the simultaneous measurement of four separately polarized beams upon diffraction from a substrate in order to determine properties of the substrate. Circularly or elliptically polarized light sources are passed via up to three polarizing elements. This polarizes the light sources by 0, 45, 90 and 135°. The plurality of polarizing beamsplitters replaces the use of a phase modulator, but enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate.

Abstract: To detect whether a substrate is in a focal plane of a scatterometer, a cross-sectional area of radiation above a certain intensity value is detected both in front of and behind a back focal plane of the optical system of the scatterometer. The detection positions in front of and behind the back focal plane should desirably be equidistant from the back focal plane along the path of the radiation redirected from the substrate so that a simple comparison may determine whether the substrate is in the focal plane of the scatterometer.

Abstract: In a scatterometer, an aperture plate comprising an array of transmissive apertures is inserted into a plane in the illumination optical system that is conjugate with the pupil plane of the projection optical system. Aberrations in the optical systems can be measured by measuring the relative positions of bright spots in the pupil plane.

Abstract: To detect whether a substrate is in a focal plane of an inspection apparatus, an optical focus sensor is arranged to receive a radiation beam via an objective lens. The optical focus sensor includes a splitter configured to split the radiation beam into a first sub-beam and a second sub-beam. With an aperture and a detector in the light path of each of the sub-beams it is possible to detect whether the substrate is in focus by comparing the amount of radiation received by each of the detectors.

Abstract: The present invention refers to the simultaneous measurement of four separately polarized beams upon diffraction from a substrate in order to determine properties of the substrate. Circularly or elliptically polarized light sources are passed via up to three polarizing elements. This polarizes the light sources by 0, 45, 90 and 135°. The plurality of polarizing beam splitters replaces the use of a phase modulator, but enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate.

Abstract: To detect whether a substrate is in a focal plane of a scatterometer, a cross-sectional area of radiation above a certain intensity value is detected both in front of and behind a back focal plane of the optical system of the scatterometer. The detection positions in front of and behind the back focal plane should desirably be equidistant from the back focal plane along the path of the radiation redirected from the substrate so that a simple comparison may determine whether the substrate is in the focal plane of the scatterometer.

Abstract: In a scatterometer, an aperture plate comprising an array of transmissive apertures is inserted into a plane in the illumination optical system that is conjugate with the pupil plane of the projection optical system. Aberrations in the optical systems can be measured by measuring the relative positions of bright spots in the pupil plane.

Abstract: To detect whether a substrate is in a focal plane of a scatterometer, a cross-sectional area of radiation above a certain intensity value is detected both in front of and behind a back focal plane of the optical system of the scatterometer. The detection positions in front of and behind the back focal plane should desirably be equidistant from the back focal plane along the path of the radiation redirected from the substrate so that a simple comparison may determine whether the substrate is in the focal plane of the scatterometer.