US4522510A
Expired / Lapsed
US
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Thin film thickness measurement with thermal waves
Assignee: Therma Wave Inc
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Filing: 1983-04-01
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Granted: 1985-06-11
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Expires: 2003-04-01
Abstract
Abstract A method and apparatus for thin film thickness measurements with thermal waves in which heating and detection laser beams are focused onto the film, normal to the surface of the film, with the two beams parallel and non-coaxial.
Inventors
- 👤 Allan Rosencwaig
- 👤 Jon Opsal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:59
CPC Classifications
G; G01; G01N; G01N25/00; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0666; G01N21/00; G01N21/17; G01N21/171
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
127 words
A method for evaluating microscopic thermal features in a sample comprising: focusing an intensity modulated heating beam of energy at a microscopic spot on the surface of the sample to produce periodic thermal waves; focusing a probe beam of energy on a portion of the surface of the sample which is being periodically heated by the thermal waves, with said probe beam being substantially parallel to and laterally spaced from the heating beam; and monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beam can be used to evaluate microscopic thermal features in a sample.
Claim 2
Independent Claim
127 words
A method for evaluating microscopic thermal features in a sample comprising: focusing an intensity modulated heating beam of energy at a microscopic spot on the surface of the sample to produce periodic thermal waves; focusing a probe beam of energy on a portion of the surface of the sample which is being periodically heated by the thermal waves, with said probe beam being substantially parallel to and laterally spaced from the heating beam; and monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beam can be used to evaluate microscopic thermal features in a sample.
Claim 3
Dependent Claim
33 words
The method of evaluating microscopic thermal features of claim 1 further including the step of modifying the evaluation to compensate for thermal air lens effects, thermal film lens effects, and optical absorption length.
Claim 4
Independent Claim
144 words
A method for detecting thermal waves in a sample, said thermal waves being generated by a periodic heat source defined by an intensity modulated beam of energy comprising: focusing said intensity modulated heating beam of energy at a microscopic spot on the surface of the sample to produce periodic thermal waves; focusing a probe beam of energy on a portion of the surface of the sample which is being periodically heated by the thermal waves, with said probe beam being substantially parallel to and laterally spaced from the heating beam; and monitoring the periodic angular displacement of the reflected probe beam, said periodic angular displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the probe beam can be used to detect the thermal waves in the sample.
Claim 5
Independent Claim
144 words
A method for detecting thermal waves in a sample, said thermal waves being generated by a periodic heat source defined by an intensity modulated beam of energy comprising: focusing said intensity modulated heating beam of energy at a microscopic spot on the surface of the sample to produce periodic thermal waves; focusing a probe beam of energy on a portion of the surface of the sample which is being periodically heated by the thermal waves, with said probe beam being substantially parallel to and laterally spaced from the heating beam; and monitoring the periodic angular displacement of the reflected probe beam, said periodic angular displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the probe beam can be used to detect the thermal waves in the sample.
Claim 6
Dependent Claim
33 words
The method of evaluating microscopic thermal features of claim 3 further including the step of modifying the evaluation to compensate for thermal air lens effects, thermal film lens effects, and optical absorption length.
Claim 7
Independent Claim
158 words
An apparatus for evaluating microscopic thermal features in a sample comprising: a heating beam of energy; means for intensity modulating said heating beam; optical means for focusing the intensity modulated heating beam at a microscopic spot on the surface of the sample to generate periodic thermal waves; a probe beam of energy; means for directing the probe beam towards and through said optical means such that the heating and probe beams are directed along substantially parallel, noncoaxial paths, with said probe beam being focused on a portion of the surface of the sample which is being periodically heated by the thermal waves; and means for monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beams can be used to evaluate microscopic thermal features in a sample.
Claim 8
Independent Claim
158 words
An apparatus for evaluating microscopic thermal features in a sample comprising: a heating beam of energy; means for intensity modulating said heating beam; optical means for focusing the intensity modulated heating beam at a microscopic spot on the surface of the sample to generate periodic thermal waves; a probe beam of energy; means for directing the probe beam towards and through said optical means such that the heating and probe beams are directed along substantially parallel, noncoaxial paths, with said probe beam being focused on a portion of the surface of the sample which is being periodically heated by the thermal waves; and means for monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beams can be used to evaluate microscopic thermal features in a sample.
Claim 9
Dependent Claim
18 words
An apparatus as recited in claim 4 wherein the modulated heating beam is defined by a laser beam.
Claim 10
Dependent Claim
17 words
An apparatus as recited in claim 6 wherein the probe beam is defined by a laser beam.
Claim 11
Dependent Claim
33 words
An apparatus as recited in claim 7 wherein the wavelength of the optical output of the probe laser beam is different from the wavelength of the optical output of the heating laser beam.
Claim 12
Dependent Claim
42 words
An apparatus as recited in claim 8 wherein the means for directing the probe beam towards and through said optical means is defined by a dichroic mirror which reflects the probe laser beam while permitting the heating laser beam to pass therethrough.
Claim 13
Dependent Claim
21 words
An apparatus as recited in claim 5 further including a means for directing said reflected probe beam to said monitoring means.
Claim 14
Dependent Claim
34 words
An apparatus as recited in claim 10 wherein said means for directing said probe beam to said monitoring means is defined by a combination of a quarter wave plate and a polarizing beam splitter.
Claim 15
Dependent Claim
28 words
An apparatus as recited in claim 5 wherein said optical means is oriented to direct said intensity modulated heating beam substantially normal to the surface of the sample.
Claim 16
Independent Claim
162 words
An apparatus for detecting thermal waves in a sample, said thermal waves being generated by a periodic heat source defined by an intensity modulated beam of energy comprising: means for focusing the intensity modulated heating beam at a microscopic spot on the surface of the sample to generate periodic thermal waves; a probe beam of energy; means for directing the probe beam towards and through said optical means such that the heating and probe beams are directed along substantially parallel, noncoaxial paths, with said probe beam being focused on a portion of the surface of the sample which is being periodically heated by the thermal waves; and means for monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beam can be used to detect the thermal waves in the sample.
Claim 17
Independent Claim
162 words
An apparatus for detecting thermal waves in a sample, said thermal waves being generated by a periodic heat source defined by an intensity modulated beam of energy comprising: means for focusing the intensity modulated heating beam at a microscopic spot on the surface of the sample to generate periodic thermal waves; a probe beam of energy; means for directing the probe beam towards and through said optical means such that the heating and probe beams are directed along substantially parallel, noncoaxial paths, with said probe beam being focused on a portion of the surface of the sample which is being periodically heated by the thermal waves; and means for monitoring the periodic angular displacement of the reflected probe beam, said periodic displacement resulting from the periodic angular changes in the surface conditions of the sample induced by the periodic thermal waves whereby the periodic angular displacement of the reflected probe beam can be used to detect the thermal waves in the sample.
Claim 18
Dependent Claim
18 words
An apparatus as recited in claim 13 wherein the modulated heating beam is defined by a laser beam.
Claim 19
Dependent Claim
17 words
An apparatus as recited in claim 14 wherein the probe beam is defined by a laser beam.
Claim 20
Dependent Claim
33 words
An apparatus as recited in claim 15 wherein the wavelength of the optical output of the probe laser beam is different from the wavelength of the optical output of the heating laser beam.
Claim 21
Dependent Claim
41 words
An apparatus as recited in claim 16 wherein means for directing the probe beam towards and through said optical means is defined by a dichroic mirror which reflects the probe laser beam while permitting the heating laser beam to pass therethrough.
Claim 22
Dependent Claim
21 words
An apparatus as recited in claim 13 further including a means for directing said reflected probe beam to said monitoring means.
Claim 23
Dependent Claim
34 words
An apparatus as recited in claim 18 wherein said means for directing said probe beam to said monitoring means is defined by a combination of a quarter wave plate and a polarizing beam splitter.
Claim 24
Dependent Claim
28 words
An apparatus as recited in claim 13 wherein said optical means is oriented to direct said intensity modulated heating beam substantially normal to the surface of the sample.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-10 | 1988-12-10 | 1989-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-10 | 1992-12-10 | 1993-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-10 | 1996-12-10 | 1997-06-11 | $7700.00 | Window Closed / Lapsed |