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US 7,139,081 B2Granted
Interferometry method for ellipsometry, reflectometry, and scatterometry measurements, including characterization of thin film structures
AssigneeZygo Corporation
InventorPeter J. De Groot
Life of this patent
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Abstract
A method including: imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a common source; for each of the angles, simultaneously varying an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object; and determining an angle-dependence of an optical property of the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.
Claims53
A method comprising:
- imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a common source;
- for each of the angles, simultaneously varying an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object;
- and determining an angle-dependence of an optical property of the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.
A method comprising:
- imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a monochromatic, common source and wherein the test object comprises at least one thin film on a substrate;
- for each of the angles, simultaneously varying an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object;
- and
- determining a thickness of the thin film based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.
1 more element
An apparatus comprising:
- a light source;
- a detector;
- a scanning interferometer configured to image test light emerging from a test object over a range of angles to interfere with reference light on the detector, wherein the test and reference light are derived from the light source,
- wherein for each of the angles, the scanning interferometer is further configured to simultaneously vary an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object;
- and
- an electronic processor coupled to the detector and the scanning interferometer, wherein the electronic processor is configured to determine an angle-dependence of an optical property of the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles as measured by the detector.
3 more elements
An apparatus comprising:
- a monochromatic light source;
- a detector;
- a scanning interferometer configured to image test light emerging from a test object over a range of angles to interfere with reference light on the detector,
- wherein the test and reference light are derived from the monochromatic light source, wherein for each of the angles, the scanning interferometer is further configured to simultaneously vary an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object;
- and an electronic processor coupled to the detector and the scanning interferometer, wherein the electronic processor is configured to determine a thickness of a thin film on the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.
2 more elements
An apparatus comprising:
- a scanning interferometer configured to image test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a common source,
- wherein for each of the angles, the scanning interferometer is further configured to simultaneously vary an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object,
- wherein the interferometer comprises an objective lens positioned to collect the test light emerging from the test object and at least one polarization optic positioned in a pupil plane of the objective.
An apparatus comprising:
- a scanning interferometer configured to image test light emerging from a test object over a range of angles to interfere with reference light on a detector,
- wherein the test and reference light are derived from a common source,
- wherein for each of the angles, the scanning interferometer is further configured to simultaneously vary an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object,
- wherein the interferometer comprises a source module configured to illuminate the test object with substantially collimated light.
1 more element
Dependencies are inferred from the claim text.