Abstract: A measurement system (22) for measuring the position of a work piece (28) along a first axis includes a grating (234), and an encoder head (238) that directs a first measurement beam (240) at the grating (234) at a first angle, and directs a second measurement beam (242) at the grating (234) at a second angle. An absolute value of the first angle relative to a normal (244) of the grating (234) is different from an absolute value of the second angle relative to the normal (244) of the grating (234). Additionally, the first measurement beam (240) has a first wavelength, and the second measurement beam (242) has a second wavelength that can be different from the first wavelength. Further, the first measurement beam (240) and the second measurement beam (242) can impinge at approximately the same location on the grating (234).

Abstract: Two dimensional encoder system and method designed to improve accuracy, compactness, stability, resolution, and/or light efficiency of metrology carried out with such system and method. Embodiments employ a novel retroreflector which while particularly useful in present invention, is believed to have more general utility in optical imaging systems and methods.

Abstract: A beam adjuster assembly (14) receives an input beam (16) and provides a first output beam (18) and a spaced apart second output beam (20). The beam adjuster assembly (14) comprises a first frequency adjuster (22) and a second frequency adjuster (24). The first frequency adjuster (22) receives the input beam (16). The first frequency adjuster (22) transmits a first portion of the input beam (16) to provide the first output beam (18) having a first output frequency. Additionally, the first frequency adjuster (22) adjusts a second portion of the input beam (16) to provide a first adjusted beam (354). The second frequency adjuster (24) receives the first adjusted beam (354). Moreover, the second frequency adjuster (24) adjusts at least a portion of the first adjusted beam (354) to provide the second output beam (20) having a second output frequency that is different than the first output frequency.

Abstract: Interferometer system and method for use in a level sensor of an exposure apparatus and autofocus system employing same. Operating either at a single or multiple wavelengths, the interferometric system employs two diffraction orders, formed by diffraction grating of the system, as reference and sample beams and is structured to ensure that only light contained in one of the two orders interacts with a wafer under test, thereby ensuring that no interference fringes are projected onto the sample. The diffraction grating is positioned such that its grooves are nominally perpendicular to the direction of wafer scan. Based on measurement data representing interference between reference and sample beams at the detector, a determination of change in position of the wafer in the sample arm is made with increased sensitivity and/or resolution.

Abstract: Fringe projection autofocus systems are provided with variable pitch diffraction gratings or multiple diffraction gratings so that a reference beam and a measurement beam propagate along a common path. Alternatively, an input beam can be directed to a diffraction grating so that the selected diffraction orders propagate along a common path. In some examples, distinct spectral bands are used for reference and measurement beams.

Abstract: A measurement system for measuring the position of a work piece (28) includes a stage grating (234) and an encoder head (236). A first measurement beam (38A) is directed at the stage grating (234) at a first angle, the first measurement beam (38A) being at a first wavelength. A second measurement beam (38B) is directed at the stage grating (234) at a second angle that is different than the first angle, the second measurement beam (38B) being at a second wavelength that is different than the first wavelength. At least a portion of the first measurement beam (38A) and at least a portion of the second measurement beam (38B) are interfered with one another to create a measurement signal along a signal axis.

Abstract: A method and apparatus are provided, for improving contrast detected in a fringe projection autofocus system that projects light from a substrate to a digital camera. The method and apparatus reduce the fill factor of the digital camera in a direction that improves the contrast at spatial frequencies near or above the Nyquist limit in that direction.

Abstract: An autofocus (AF) system and method is provided that maps the topography of a substrate such as a semiconductor wafer, in a manner that corrects for Goos Hanchen (GH) effect. In addition, a new and useful detector is provided that is particularly useful in an AF system and method. The detector preferably has both color and polarization filtering integrally associated with the detector, so that polarization and color filtering is provided at the detector, on a pixel by pixel basis.

Abstract: An exemplary device has a stationary portion and a movable portion. The stationary portion has a first corner-cube, an optical system including a beamsplitter, and a light detector. The movable portion comprises a second corner-cube mountable on an object that is displaceable in a principal direction relative to the stationary portion. The beamsplitter splits a beam of collimated broadband light into a reference beam and a measurement beam that are directed by the optical system to make multiple roundtrip passes from the optical system to the respective corner cubes and back. The reference beam and measurement beam interfere with each other to produce a coherence envelope sensed by the detector, wherein a detected displacement of the coherence envelope corresponds to a respective position of the object in the principal direction.

Abstract: Methodology of measuring a position of a wafer with an encoder directing measurement beam(s) of light towards a wafer area that is being contemporaneously patterned in an exposure apparatus. The Abbe error of such measurement is minimized or even negated by combining the data from first and second measurement signals, one of which is defined as complementary, Abbe-error correcting measurement signal for which the induced Abbe error is either opposite to or at least different from the Abbe error corresponding to another, main measurement signal. The combination of the main and Abbe-error correcting signals is performed with a heterodyne interferometer employing a two-dimensional diffraction grating diffracting each of the measurement beams twice.

Abstract: An autofocus system and method designed to account for instabilities in the system, e.g. due to instabilities of system components (e.g. vibrating mirrors, optics, etc) and/or environmental effects such as refractive index changes of air due to temperature, atmospheric pressure, or humidity gradients, is provided. An autofocus beam is split into a reference beam component (the split off reference channel) and a measurement beam component, by a beam splitting optic located a predetermined distance from (and in predetermined orientation relative to) the substrate, to create a first space between the beam splitting optic and the substrate. A reflector is provided that is spaced from the beam splitting optic by the predetermined distance, to create a second space between the reflector and the beam splitting optic.

Abstract: A measurement system (22) for measuring the position of a work piece (28) includes a measurement grating (34) and an encoder head (36). The encoder head (36) directs a measurement beam (252) at the measurement grating (34), the measurement beam (252) having an oval shaped cross-section. The encoder head (36) includes a beam shape adjuster (256) positioned in the path of an input measurement beam (240) having a substantially circular cross-sectional shape that transforms the input measurement beam (240) to provide the measurement beam (252) having the oval shaped cross-section.

Abstract: Fringe patterns at first and second spatial frequencies are projected onto a work piece surface and a reference surface, respectively. An image of the projected fringe patterns is obtained and a measurement signal associated with work piece displacements and a reference signal are obtained based on the first and second spatial frequencies. The image of the projected fringe patterns can exhibit substantial or complete overlap of the fringe patterns at the first and second spatial frequencies, and the overlapping patterns can be separated based on the spatial frequencies. Fringe pattern shifts at one or both of the first and second spatial frequencies can be used to adjust a pattern transfer system to permit accurate pattern transfer.

Abstract: Autofocus system (AF) employing, in addition to specified optical units, fringe projection and fringe detection systems (FPS, FDS) and specifically-configured data processing system. AFS is configured to project with FPS a sinusoidal fringe pattern, formed by a pattern source, on a substrate and to image the so projected pattern from substrate onto optical detector with FDS to form optical image from which topology of the substrate is defined as substrate moves relative to the projected pattern. Pattern source may include diffraction grating oriented that the projected pattern is inclined relative to direction of substrate scanning Topology profile is corrected for tilt of substrate, Goos-Hanchen errors, and for fringe-pattern-induced errors outside a chosen spatial-frequency range. To reduce errors of topology profile, at least five values of phase difference are used. AFS is configured to define temporal phase shifting in optical image without using any moving parts in the AFS.

Abstract: A detector (550) for detecting light (248B) from a light source (248A) comprises a single array of pixels (574) and a first mask (576). The single array of pixels (574) includes a plurality of rows of pixels (574R), and a plurality of columns of pixels (574C) having at least a first active column of pixels (574AC) and a spaced apart second active column of pixels (574AC). The first mask (576) covers one of the plurality of columns of pixels (574C) to provide a first masked column of pixels (574MC) that is positioned between the first active column of pixels (574AC) and the second active column of pixels (574AC). Additionally, a charge is generated from the light (248B) impinging on the first active column of pixels (574AC), is transferred to the first masked column of pixels (574MC), and subsequently is transferred to the second active column of pixels (574AC).

Abstract: Fringe-projection autofocus system devoid of a reference mirror. Contributions to error in determination of a target surface profile caused by air non-uniformities measured based on multiple measurements of the target surface performed at different wavelengths, and/or angles of incidence, and/or grating pitches and subtracted from the measured profile, rendering the system substantially insensitive to presence of air turbulence. Same optical beams forming a fringe irradiance pattern on target surface are used for measurement of the surface profile and reduction of measurement error by the amount attributed to air turbulence.

Abstract: Two dimensional encoder system and method designed to improve accuracy, compactness, stability, resolution, and/or light efficiency of metrology carried out with such system and method. Embodiments employ a novel retroreflector which while particularly useful in present invention, is believed to have more general utility in optical imaging systems and methods.

Abstract: A new and useful method is provided for Goos-Hanchen compensation in an optical autofocus (AF) system that uses light reflected from a substrate to determine changes in the z position of a substrate. According to the method of the invention reflected light from the substrate is provided at a plurality of wavelengths and polarizations, detected and used to make corrections that compensate for the errors due to the Goos-Hanchen effect.

Abstract: An encoder system and method are provided, that is designed to improve 2D encoder systems and methods in areas such as accuracy, compactness, stability, resolution, and/or light efficiency. Moreover, the system and method of this invention provides a new concept in a retroreflector that while particularly useful in applicants' system and method, is believed to have more general utility in optical imaging systems and methods.

Abstract: An autofocus system and method designed to account for instabilities in the system, e.g. due to instabilities of system components (e.g. vibrating mirrors, optics, etc) and/or environmental effects such as refractive index changes of air due to temperature, atmospheric pressure, or humidity gradients, is provided. An autofocus beam is split into a reference beam component (the split off reference channel) and a measurement beam component, by a beam splitting optic located a predetermined distance from (and in predetermined orientation relative to) the substrate, to create a first space between the beam splitting optic and the substrate. A reflector is provided that is spaced from the beam splitting optic by the predetermined distance, to create a second space between the reflector and the beam splitting optic.