Zygo Corporation

Zetetic Institute

University of Arizona

Other

Flir Systems, Incorporated

Henry Allen Hill

Peter J De Groot

Frank C Demarest

Gary Womack

Justin Lloyd Kreuzer

Paul T Ballard

Andrew Eric Carlson

John W Figoski

Jeffrey Ross Johnston

David W Gardner

Michael Schroeder

Alan H Field

P De Groot

Douglas A Ziebell

Paul H Oglesby

An alignment metrology and resolution measurement system concurrently determines the alignment of an imaging array in six degrees of freedom relative to an external reference frame, and further determines the resolution of the imaging array. To achieve this, an image of at least three mask patterns is projected on the imaging array. First and second positions of the imaging array relative to first and second coordinate axis of the reference frame is obtained using pixel positions of the images along the first and second axis. A first rotational position of the imaging array about a third coordinate axis is obtained using pixel positions of the images along the first and second axes. The third position and the second and third rotational positions of the imaging array about the first and second coordinate axis are determined using feature widths of focus images of the patterns and distances between the mask patterns.

Alignment metrology and resolution measurement system for imaging arrays

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.

Multiple-degree of freedom interferometer with compensation for gas effects

In general, in a first aspect, the invention features a method that includes using an interferometry assembly to provide three different output beams, each output beam including an interferometric phase related to an optical path difference between a corresponding first beam and a corresponding second beam, each first beam contacting a measurement object at least once, monitoring the interferometric phases for each of the three different output beams, and deriving information about variations in the optical properties of a gas in the first beam paths from the three monitored phases.

Compensation of effects of atmospheric perturbations in optical metrology

In general, in one aspect, the invention features a system that includes a moveable stage, an interferometer configured to provide information about a first degree of freedom of the stage, an encoder configured to provide information about a second degree of freedom of the stage, and an electronic processor configured to monitor the position of the stage based on the information about the first and second degrees of freedom.

Distance measuring interferometer and encoder metrology systems for use in lithography tools

We disclose acousto-optic modulators that include: (a) an optical element configured to receive an input optical beam that propagates along a first direction; and (b) a transducer extending along the first direction and positioned on one or more surfaces of the optical element, the transducer having a transducer material positioned between two electrodes configured to apply a potential difference across the transducer to cause the transducer to generate an acoustic waveform propagating in a second direction in the optical element, and the input optical beam undergoing diffraction in a region of the optical element that includes the acoustic waveform. The transducer extends along a third direction orthogonal to the first and second directions, and at least one of the transducer material and the electrodes has a maximum length L along the third direction and is shaped so that the acoustic waveform has a reduced phase variation within a central region of length L of the waveform in the third direction, relative to a phase variation within a central region of length L in the third direction of an acoustic waveform generated by a rectangular transducer.

Apparatus for reducing wavefront errors in output beams of acousto-optic devices

A test object including: an arrangement of optical elements defining a first partially reflecting surface and a second partially reflecting surface, at least one of the first and second partially reflecting surfaces being curved, wherein the first partially reflecting surface is arranged to receive a substantially collimated input beam and produce therefrom a first transmitted beam that passes on to the second partially reflecting surface, wherein the second partially reflecting surface is arranged to receive the first transmitted beam from the first partially reflecting surface and produce a collimated second transmitted beam and a first reflected beam therefrom, wherein the first partially reflecting surface is arranged to receive the first reflected beam and produce a second reflected beam therefrom, and wherein the first and second reflecting surfaces are configured to cause the second reflecting beam to converge onto a spot on a back surface to produce a diverging beam traveling in the same direction as the collimated output beam.

Apparatus and method for in situ and ex situ measurement of spatial impulse response of an optical system using phase shifting point-diffraction interferometry

An interference signal S(t) is provided from interference between two beams directed along different paths. The signal S(t) is indicative of changes in an optical path difference n{tilde over (L)}(t) between the different paths, where n is an average refractive index along the different paths, {tilde over (L)}(t) is a total physical path difference between the different paths, and t is time. An error signal is provided to reduce errors in an estimate of {tilde over (L)}(t). The error signal is derived at least in part based on one or more collective properties of a distribution of multi-dimensional values. At least one of the multi-dimensional values in the distribution is generated from a plurality of samples of the signal S(t) (e.g., samples of the signal captured at different times).

Cyclic error compensation in interferometry systems

In general, in one aspect, the invention features an apparatus including a multi-axis interferometer configured to produce at least three output beams each including interferometric information about a distance between the interferometer and a measurement object along a corresponding measurement axis, wherein at least three of the measurement axes are in a common plane, wherein the output beams each include a component that makes a pass to the measurement object along a common beam path.

Multi-axis interferometers and methods and systems using multi-axis interferometers

Methods and systems for determining information about the incident angle of a beam are disclosed, the method including directing a beam having an s-polarized component and a p-polarized component to reflect from an interface at a non-normal angle, where the non-normal reflection introduces for each component a phase change upon reflection that is different for each component, and measuring an optical interference signal related to the phase change between the components of the reflected beam.

Angle interferometers

In general, in one aspect, the invention features interferometry systems that include an interferometer configured to direct a first beam and a second beam derived from common light source along different paths and to combine the two beams to form an output beam including information related to an optical path difference between the different paths, wherein the path of the first beam contacts a measurement object. The interferometry systems also include an afocal system positioned in the path of the first beam and configured to increase a dimension of the first beam as it propagates from the interferometer towards the measurement object and reduces the dimension of the first beam as it returns from the measurement object propagating towards the interferometer.

Apparatus and methods for reducing non-cyclic non-linear errors in interferometry

Compensation of turbulent effects of gas in measurement paths of multi-axis interferometers

A point diffraction interferometer for measuring properties of a spatial impulse response function, the interferometer including: a source for generating a source beam; an optical system; an optical element including a test object located in an object plane of the optical system, the test object including a diffraction point for generating from the source beam a measurement beam that passes through the optical system, wherein the optical element also generates from the source beam a reference beam that is combined with the measurement beam to generate an interference pattern in an image plane of the optical system, the interference pattern representing the spatial impulse response function of the optical system.

Apparatus and method of in situ and ex situ measurement of spatial impulse response of an optical system using phase-shifting point-diffraction interferometry

An interferometery system for making interferometric measurements of an object, the system including: a beam generation module which during operation delivers an output beam that includes a first beam at a first frequency and a second beam at a second frequency that is different from the first frequency, the first and second beams within the output beam being coextensive, the beam generation module including a beam conditioner which during operation introduces a sequence of different shifts in a selected parameter of each of the first and second beams, the selected parameter selected from a group consisting of phase and frequency; a detector assembly having a detector element; and an interferometer constructed to receive the output beam at least a part of which represents a first measurement beam at the first frequency and a second measurement beam at the second frequency, the interferometer further constructed to image both the first and second measurement beams onto a selected spot on the object to produce therefrom corresponding first and second return measurement beams, and to then simultaneously image the first and second return measurement beams onto said detector element.

Apparatus and method for joint measurements of conjugated quadratures of fields of reflected/scattered and transmitted beams by an object in interferometry

In certain aspects, the invention features interferometry systems that include an input assembly positioned to receive a beam emitted from a light source comprising a first component beam and a second component beam, the input assembly being configured to change a dimension of one of the component beams relative to the dimension of the other component beam, an interferometer positioned to receive the component beams propagating from the input assembly, the interferometer being configured to direct the component beams along different paths and to produce an output beam by directing the component beams along a common path, wherein the output beam comprises information about an optical path difference between the different component beam paths, and an output assembly positioned in the path of the output beam and configured to change a dimension of the component beam that contacts the measurement object.

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Tucson, AZ, United States of America

Henry Allen Hill