Zygo Corporation Patent applications |
Patent application number | Title | Published |
20140268105 | OPTICAL DEFECT INSPECTION SYSTEM - Disclosed herein is a system for determining information about one or more defects on or in a test object. The system includes a light source configured to illuminate a test object with spatially coherent light; a multi-element detector positioned to detect an interference pattern of light associated with one or more defects on or in the illuminated test object; and an electronic control module in communication with the multi-element detector and configured to process the interference pattern to determine information about the one or more defects on or in the test object. | 09-18-2014 |
20140049782 | INTERFEROMETRIC ENCODER SYSTEMS - A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase. | 02-20-2014 |
20130278914 | NON-HARMONIC CYCLIC ERROR COMPENSATION IN INTERFEROMETRIC ENCODER SYSTEMS - A method includes obtaining, from a detector of an interferometry system, an interference signal based on a combination of a first beam and a reference beam, subsequent to the first beam being diffracted by an encoder scale, obtaining, through an electronic processor, an error compensation signal based on a non-harmonic cyclic error that modifies the interference signal, and outputting information about a change in a position of the encoder scale relative to an optical assembly of the interferometry system based on the interference signal and the error compensation signal. | 10-24-2013 |
20130155413 | LOW COHERENCE INTERFEROMETRY WITH SCAN ERROR CORRECTION - A system includes an interference microscope having one or more optical elements arranged to image a test object to an image plane by combining test light from the test object with reference light from a reference object to form an interference pattern at the image plane, wherein the test and reference light are derived from a common broadband light source. The system includes a scanning stage configured to scan an optical path difference (OPD) between the test and reference light, a multi-element detector positioned at the image plane and configured to record the interference pattern for each of a series of OPD increments and to generate multiple interferometry signals each having a fringe carrier frequency indicative of changes in the OPD as the OPD is scanned, where there is phase diversity among the interferometry signals, and an electronic processor coupled to the multi-element detector and scanning stage and configured to process the interference signals based on the phase diversity to determine information about the OPD increments having sensitivity to perturbations to the OPD increments at frequencies greater than the fringe carrier frequency. | 06-20-2013 |
20130128254 | Thermally Stable Optical Sensor Mount - Disclosed is an apparatus including a mechanical reference frame and a rigid object mechanically coupled to the reference frame by two or more constraints. The stiffnesses of at least two of the constraints are different from one another, and the relative locations and stiffnesses of the constraints cause a designated point on the rigid object to remain stationary with respect to the reference frame during thermal expansion of the rigid object over a range of temperatures. | 05-23-2013 |
20130128249 | Fiber Delivery for Metrology Systems Used in Lithography Tools - Metrology system, apparatus and method used to implement measurements inside a lithography tool are described, such that the disclosed measurements can be performed without contributing outgassed effluent within the lithography tool. Disclosed is a system including: an objective for projecting an image of an object positioned at an object plane to an image plane; a stage to execute motions relative to the objective while supporting the wafer at the image plane; an optical sensor for producing an optical monitoring signal associated with the motions of the stage; and a glass optical fiber having a metal outer coating, the metal-coated glass optical fiber being arranged to provide light to, or collect light from, the optical sensor. | 05-23-2013 |
20130114087 | LOW COHERENCE INTERFEROMETRY USING ENCODER SYSTEMS - A method for determining information about changes in a position of an encoder scale includes separating, in a first interferometry cavity, a low coherence beam into a first beam propagating along a first path of the first interferometry cavity and a second beam propagating along a second path of the first interferometry cavity, combining the first beam and the second beam to form a first output beam, separating, in a second interferometry cavity, the first output beam into a measurement beam propagating along a measurement path of the second interferometry cavity and a reference beam propagating along a reference path of the second interferometry cavity, combining the measurement beam and the reference beam to form a second output beam, detecting an interference signal based on the second output beam, and determining the information about changes in the position of the encoder scale based on phase information from the interference signal. | 05-09-2013 |
20130114062 | COMPACT ENCODER HEAD FOR INTERFEROMETRIC ENCODER SYSTEM - An encoder system includes an encoder scale and an encoder head, in which the encoder head is configured to combine each twice-diffracted measurement beam of multiple twice-diffracted measurement beams with a corresponding reference beam to form multiple output beams, where the encoder head includes a monolithic optical component having multiple facets, the multiple facets being arranged to: receive multiple once-diffracted measurement beams from a surface of the encoder scale; and redirect the multiple once-diffracted measurement beams back towards the surface of the encoder scale, the encoder scale being positioned in a path of the once-diffracted measurement beams to produce the twice-diffracted measurement beams. | 05-09-2013 |
20130114061 | DOUBLE PASS INTERFEROMETRIC ENCODER SYSTEM - An encoder head includes one or more components arranged to: i) direct a first incident beam to the diffractive encoder scale at a first incident angle with respect to the encoder scale; ii) receive a first return beam from the encoder scale at a first return angle, the first return angle being different from the first incident angle; iii) redirect the first return beam to the encoder scale as a second incident beam at a second incident angle; and iv) receive a second return beam back from the encoder scale at a second return angle, the second return angle being different from the second incident angle, in which a difference between the first incident angle and second incident angle is less than a difference between the first incident angle and the first return angle and less than a difference between the second incident angle and the second return angle. | 05-09-2013 |
20130063730 | IN SITU CALIBRATION OF INTERFEROMETERS - In-situ calibration of an interferometer includes making a sequence of phase measurements of a test object using the interferometer, each of the measurements having a same carrier fringe frequency, where at least some of the measurements are made at three or more different orientations of carrier fringes, and determining information about the test object based on at least some of the phase measurements, in which determining the information includes reducing errors in the measurements arising from imperfections in the interferometer based on the measurements made at the three or more different orientations. | 03-14-2013 |
20120229621 | OBJECT THICKNESS AND SURFACE PROFILE MEASUREMENTS - Determining spatial information about a part includes positioning the part in a fixture having two reference surfaces, where the part is positioned between the two reference surfaces, imaging the two reference surfaces and opposing surfaces of the part to different locations of a multi-element detector, simultaneously acquiring images of the opposing sides of the part and the two reference surfaces using the multi-element detector, and determining spatial information about the part based on the simultaneously acquired images. | 09-13-2012 |
20120224183 | INTERFEROMETRIC METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - An interferometry method for determining information about a test object includes directing test light to the test object positioned at a plane, wherein one or more properties of the test light vary over a range of incidence angles at the plane, the properties of the test light being selected from the group consisting of the spectral content, intensity, and polarization state; subsequently combining the test light with reference light to form an interference pattern on a multi-element detector so that different regions of the detector correspond to different angles of the test light emerging from the test object, wherein the test and reference light are derived from a common source; monitoring the interference pattern using the multi-element detector while varying an optical path difference between the test light and the reference light; determining the information about the test object based on the monitored interference pattern. | 09-06-2012 |
20120194824 | INTERFEROMETRIC HETERODYNE OPTICAL ENCODER SYSTEM - An encoder interferometry system includes an interferometer positioned to receive first and second beams having different frequencies, in which the interferometer has at least one polarizing beam splitting element for directing the first beam along a measurement path to define a measurement beam and the second beam along a reference path to define a reference beam. The encoder interferometry system further includes a encoder scale positioned to diffract the measurement beam at least once, a detector positioned to receive the measurement and reference beams after the measurement beam diffracts from the encoder scale, and an output component positioned to receive the measurement and reference beams before they reach the detector and deflect spurious portions of the first and second beam away from the detector. | 08-02-2012 |
20120170048 | INTERFEROMETRIC ENCODER SYSTEMS - A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase. | 07-05-2012 |
20120154780 | CYCLIC ERROR COMPENSATION IN INTERFEROMETRIC ENCODER SYSTEMS - Methods and apparatuses for performing the same, where the methods include obtaining, from an interferometer, a time-varying interference signal S(t) based on a combination of a first beam and a second beam, the first beam being diffracted from an encoder scale, in which at least one of the encoder scale and the interferometer is moveable with respect to the other, obtaining one or more error correction signals based on one or more errors that modify the time-varying interference signal S(t), and outputting information about a change in a position of the encoder scale relative to the interferometer based on the time-varying interference signal S(t) and the one or more error correction signals. | 06-21-2012 |
20120140243 | NON-CONTACT SURFACE CHARACTERIZATION USING MODULATED ILLUMINATION - Methods for forming a three-dimensional image of a test object include directing light to a surface of best-focus of an imaging optic, where the light has an intensity modulation in at least one direction in the surface of best-focus, scanning a test object relative to the imaging optic so that a surface of the measurement object passes through the surface of best-focus of the imaging optic as the test object is scanned, acquiring, for each of a series of positions of the test object during the scan, a single image of the measurement object using the imaging optic, in which the intensity modulation of the light in the surface of best-focus is different for successive images, and forming a three-dimensional image of the test object based on the acquired images. | 06-07-2012 |
20120120411 | INTERFEROMETER WITH A VIRTUAL REFERENCE SURFACE - An imaging interferometer includes optics defining an interferometric cavity, in which the optics include a first beam-splitting optic positioned to separate an input beam into a test beam and a reference beam, a second beam-splitting optic positioned to transmit the test beam to the test surface, receive the test beam back from the test surface, and thereafter recombine the test beam with the reference beam, and a third optic positioned to direct the reference beam from the first optic to the second optic. The interferometric cavity defines a virtual reference surface positioned along a path for the reference beam between the second and third optics. The interferometer also includes an imaging channel positioned to receive the recombined test and reference beams, where the imaging channel includes an imaging detector, and at least one imaging element configured to image the test surface and the virtual reference surface onto the detector. | 05-17-2012 |
20120089365 | DATA INTERPOLATION METHODS FOR METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - A method includes fitting a function to a subset of reflectivity data comprising values for the reflectivity of a test object for different wavelengths, different scattering angles, and/or different polarization states; determining values for the function at certain wavelengths and scattering angles and/or polarization states; and determining information about the test object based on the determined values. | 04-12-2012 |
20120069326 | INTERFEROMETRIC METHODS FOR METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - A method for determining information about a test object includes combining two or more scanning interference signals to form a synthetic interference signal; analyzing the synthetic interference signal to determine information about the test object; and outputting the information about the test object. Each of the two or more scanning interference signals correspond to interference between test light and reference light as an optical path length difference between the test and reference light is scanned, wherein the test and reference light are derived from a common source. The test light scatters from the test object over a range of angles and each of the two or more scanning interferometry signals corresponds to a different scattering angle or polarization state of the test light. | 03-22-2012 |
20110255096 | INTERFEROMETRIC ENCODER SYSTEMS - A method for determining information about changes along a degree of freedom of an encoder scale includes directing a first beam and a second beam along different paths and combining the first and second beams to form an output beam, where the first and second beams are derived from a common source, the first and second beams have different frequencies, where the first beam contacts the encoder scale at a non-Littrow angle and the first beam diffracts from the encoder scale at least once; detecting an interference signal based on the output beam, the interference signal including a heterodyne phase related to an optical path difference between the first beam and the second beam; and determining information about a degree of freedom of the encoder scale based on the heterodyne phase. | 10-20-2011 |
20110032535 | INTERFEROMETER FOR DETERMINING OVERLAY ERRORS - Systems are disclosed that include an interferometer configured to direct test light to an overlay test pad and subsequently combine it with reference light, the test and reference light being derived from a common source, one or more optics configured to direct at least a portion of the combined light to a multi-element detector so that different regions of the detector correspond to different illumination angles of the overlay test pad by the test light, the detector being configured to produce an interference signal based on the combined light, and an electronic processor in communication with the multi-element detector. The overlay test pad comprises a first patterned structure and a second patterned structure and the electronic processor is configured to determine information about the relative alignment between the first and second patterned structures based on the interference signal. | 02-10-2011 |
20110007323 | Equal-Path Interferometer - An optical assembly for use in an interferometer is provided. The optical assembly includes first and second partially reflective surfaces positioned along an optical axis and oriented at different non-normal angles to the optical axis. The second partially reflective surface is configured to receive light transmitted through the first partially reflective surface along the optical path, transmit a portion of the received light to a test object to define measurement light for the interferometer and reflect another portion of the received light back towards the first partially reflective surface to define reference light for the interferometer. The reference light makes at least one round trip path between the second and first partially reflective surfaces. | 01-13-2011 |
20100238455 | ERROR COMPENSATION IN PHASE SHIFTING INTERFEROMETRY - In certain aspects, disclosed methods include combining reference light reflected from a reference surface with test light reflected from a test surface to form combined light, the test and reference light being derived from a common source, sinusoidally varying a phase between the test light and reference light, where the sinusoidal phase variation has an amplitude u, recording at least one interference signal related to changes in an intensity of the combined light in response to the sinusoidal variation of the phase, determining information related to the phase using a phase shifting algorithm that has a sensitivity that varies as a function of the sinusoidal phase shift amplitude, where the sensitivity of the algorithm at 2 u is 10% or less of the sensitivity of the algorithm at u. | 09-23-2010 |
20100195112 | INTERFEROMETER WITH SCAN MOTION DETECTION - An apparatus includes an interferometer configured to generate an interference pattern by combining test light from a test object with reference light reflected from a reference object, the interferometer being further configured to direct at least a first part of a monitor test beam to the test object at a first incident angle and at least a second part of a monitor reference beam to the reference object at a second incident angle, and recombine the first part and the second part of the monitor beams after they reflect from the test and reference surfaces to interfere with one another and form a monitor pattern, where the first and second angles cause the monitor pattern to have spatial interference fringes, and wherein a change in the position of the interference fringes is indicative of a change in a relative position between the test and reference objects. | 08-05-2010 |
20100128283 | INTERFEROMETRIC SYSTEMS AND METHODS FEATURING SPECTRAL ANALYSIS OF UNEVENLY SAMPLED DATA - In certain aspects, interferometry methods are disclosed that include providing one or more interferometry signals for a test object, wherein the interferometry signals correspond to a sequence of optical path difference (OPD) values which are not all equally spaced from one another because of noise, providing information about the unequal spacing of the sequence of OPD values, decomposing each of the interferometry signals into a contribution from a plurality of basis functions each corresponding to a different frequency and sampled at the unequally spaced OPD values, and using information about the contribution from each of the multiple basis functions to each of the interferometry signals to determine information about the test object. | 05-27-2010 |
20100128280 | SCAN ERROR CORRECTION IN LOW COHERENCE SCANNING INTERFEROMETRY - In general, in one aspect, the invention features apparatus that includes a broadband scanning interferometry system including interferometer optics for combining test light from a test object with reference light from a reference object to form an interference pattern on a detector, wherein the test and reference light are derived from a common light source. The interferometry system further includes a scanning stage configured to scan an optical path difference (OPD) between the test and reference light from the common source to the detector and a detector system including the detector for recording the interference pattern for each of a series of OPD increments, wherein the frequency of each OPD increment defines a frame rate. The interferometer optics are configured to produce at least two monitor interferometry signals each indicative of changes in the OPD as the OPD is scanned, wherein the detector system is further configured to record the monitor interferometry signals. The apparatus also includes an electronic processor electronically coupled to the detection system and scanning stage and configured to determine information about the OPD increments with sensitivity to perturbations to the OPD increments at frequencies greater than the frame rate. | 05-27-2010 |
20100128278 | FIBER-BASED INTERFEROMETER SYSTEM FOR MONITORING AN IMAGING INTERFEROMETER - Apparatus include a microscope including an objective and a stage for positioning a test object relative to the objective, the stage being moveable with respect to the objective, and a sensor system, that includes a sensor light source, an interferometric sensor configured to receive light from the sensor light source, to introduce an optical path difference (OPD) between a first portion and a second portion of the light, the OPD being related to a distance between the objective lens and the stage, and to combine the first and second portions of the light to provide output light, a detector configured to detect the output light from the interferometric sensor, a fiber waveguide configured to direct light between the sensor light source, the interferometric sensor and the detector, a tunable optical cavity in a path of the light from the sensor light source and the interferometric sensor, and an electronic controller in communication with the detector, the electronic controller being configured to determine information related to the OPD based on the detected output light. | 05-27-2010 |
20100128276 | COMPOUND REFERENCE INTERFEROMETER - Interferometry system are disclosed that include a detector sub-system including a monitor detector, interferometer optics for combining test light from a test object with primary reference light from a first reference interface and secondary reference light from a second reference interface to form a monitor interference pattern on a monitor detector, wherein the first and second reference interfaces are mechanically fixed with respect to each other and the test light, a scanning stage configured to scan an optical path difference (OPD) between the test light and the primary and secondary reference light to the monitor detector while the detector sub-system records the monitor interference pattern for each of a series of OPD increments, and an electronic processor electronically coupled to the detector sub-system and the scanning stage, the electronic processor being configured to determine information about the OPD increments based on the detected monitor interference pattern. | 05-27-2010 |
20100091296 | INTERFEROMETER SYSTEM FOR MONITORING AN OBJECT - System for monitoring a position of one or more optical elements in a projection objective (PO) include a plurality of sensors each configured to receive input light and to form output light, each sensor including a first sensor optic and a second sensor optic, the first sensor optic of at least one of the sensors being affixed to a first PO optical element and the second sensor optic of the at least one sensor being affixed to a support element that positions the first PO optical element within the PO, the first and second sensor optics being configured introduce a first optical path length difference (OPD) between two components of the input light to form the output light, the first OPD being related to the position of the first PO optical element with respect to the support element. The systems also include a plurality of detectors configured to detect the output light from the sensors, a plurality of optical fibers configured to direct the input light to the sensors and to direct the output light from the sensors to the detectors, and an electronic controller in communication with the plurality of detectors, the electronic controller being configured to determine information about the position of the first PO optical element relative to the support element based on the detected output light from the at least one sensor. | 04-15-2010 |
20090303493 | INTERFEROMETRY FOR LATERAL METROLOGY - A method is disclosed which includes: using a scanning interferometry system, generating a sequence of phase-shifted interferometry images at different scan positions of an object comprising a buried surface, identifying a scan position corresponding to a position of best focus for the buried surface based on the sequence of phase-shifted interferometry images of the object, and generating a final image based on the phase-shifted interferometry images and the scan position, where the interferometric fringes in the final image are reduced relative to the interferometric fringes in the phase-shifted interferometry images. | 12-10-2009 |
20090262362 | INTERFEROMETER FOR OVERLAY MEASUREMENTS - In general, in a first aspect, the invention features a system including an interferometer configured to direct test light to an overlay target and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source, a multi-element detector, one or more optics to image the overlay target on the multi-element detector; and an electronic processor in communication with the multi-element detector. The overlay target includes a first pattern and a second pattern and the electronic processor is configured to determine information about the relative alignment between the first and second patterns. | 10-22-2009 |
20090147268 | INTERFEROMETRIC ANALYSIS OF UNDER-RESOLVED FEATURES - In certain aspects, disclosed methods include directing test light reflected from an object to form an image of the object on a detector, where the object includes a diffractive structure. The test light at the detector includes both specularly and non-specularly reflected light from the diffractive structure, and the diffractive structure is under-resolved in the image. The method further includes directing reference light to interfere with the test light at the detector where the reference and test light being derived from a common source, varying an optical path length difference between the test and reference light, acquiring an interference signal from the detector while varying the optical path length difference, and determining information about the diffractive structure based on the interference signal and on predetermined information derived from a mathematical model of light reflection from a model diffractive structure. | 06-11-2009 |
20090021723 | GENERATING MODEL SIGNALS FOR INTERFEROMETRY - A method is disclosed which includes, for each of multiple areas of a test surface on a test object having different reflectivities, using an interferometry system to measure each area in a first mode of operation that measures information about the reflectivity of the area over a range of angles and wavelengths; using the same interferometry-system to measure the test surface in a second mode of operation that interferometrically profiles a topography of the test surface over a range including at least some of the multiple areas; and correcting the profile based on the information about the reflectivity of the multiple areas to reduce errors. | 01-22-2009 |
20080304077 | CYCLIC ERROR COMPENSATION IN INTERFEROMETRY SYSTEMS - A first portion of a beam including a first frequency component is directed along a first path. A second portion of the beam is frequency shifted to generate a shifted beam that includes a second frequency component different from the first frequency component and one or more spurious frequency components different from the first frequency component. At least a portion of the shifted beam is directed along a second path different from the first path. An interference signal S(t) from interference between the beam portions directed along the different paths is measured. The signal S(t) is indicative of changes in an optical path difference n{tilde over (L)}(t) between the paths, where n is an average refractive index along the paths, {tilde over (L)}(t) is a total physical path difference between the paths, and t is time. An error signal is provided to reduce errors in an estimate of {tilde over (L)}(t) that are caused by at least one of the spurious frequency components of the shifted beam, the error signal being derived at least in part based on the signal S(t). | 12-11-2008 |
20080285051 | Multiple-degree of freedom interferometer with compensation for gas effects - The disclosure features multiple degree-of-freedom interferometers (e.g., non-dispersive interferometers) for monitoring linear and angular (e.g., pitch and/or yaw) displacements of a measurement object with compensation for variations in the optical properties of a gas in the interferometer measurement (and/or reference) beam paths. The disclosure also features interferometry systems that feature an array of interferometers (e.g., including one or more multiple degree-of-freedom interferometer), each configured to provide different information about variations in the optical properties of the gas in the system. Multiple degree-of-freedom interferometers are also referred to as multi-axis interferometers. | 11-20-2008 |
20080278730 | METHODS AND SYSTEMS FOR DETERMINING OPTICAL PROPERTIS USING LOW COHERENCE INTERFERENCE SIGNALS - Methods and related systems for determining properties of optical systems (e.g., interferometers) and/or optical elements (e.g., lenses and/or lens systems) are described. For example, information related to an optical thickness mismatch of an interferometer can be determined by providing scanning interferometry data. The data typically include obtaining one or more interference signals each corresponding to a different spatial location of a test object. A phase is determined for each of multiple frequencies of each interference signal. The information related to the optical thickness mismatch is determined based on the phase for each of the multiple frequencies of the interference signal(s). | 11-13-2008 |
20080221837 | METHOD AND SYSTEM FOR ANALYZING LOW-COHERENCE INTERFEROMETRY SIGNALS FOR INFORMATION ABOUT THIN FILM STRUCTURES - Methods and systems are disclosed for analyzing a scanning interferometry signal. Steps include: providing a scanning interferometry signal produced by a scanning interferometer for a first location of a test object (e.g., a sample having a thin film); providing a model function of the scanning interferometry signal produced by the scanning interferometer, wherein the model function is parametrized by one or more parameter values; fitting the model function to the scanning interferometry signal for each of a series of shifts in scan position between the model function and the scanning interferometry signal by varying the parameter values; and determining information about the test object (e.g., a surface height or height profile, and/or a thickness or thickness profile for a thin film in the test object) at the first location based on the fitting. | 09-11-2008 |