Thin film thickness measurement with thermal waves
AssigneeTherma-Wave, Inc.
InventorsAllan Rosencwaig, Jon Opsal
Life of this patent
Estimating the term…
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.
Claims20
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.
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.
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.
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.
Dependencies are inferred from the claim text.