EP0163466A2
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Method and apparatus for evaluating both thickness and compositional variables in a layered or thin film sample
Assignee: Therma Wave Inc
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Filing: 1985-05-20
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Granted: —
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Expires: 2005-05-20
Abstract
Abstract Two independent detection systems are provided for measuring thermal waves generated in a sample (22) by a periodic, localized heating cause by a laser beam (34) modulated by a modulator (32). One detection system generates output signals that are primarily a function of the surface temperature of the sample. The other detection system generates signals that are primarily a function of the integral of the temperature beneath the sample surface. The two independent thermal wave measurements permit analysis of both thickness and compositional variables. Both detection systems are implemented efficiently by one apparatus consisting of an He-Ne laser (50) directing a probe beam (52) through a polarising splitter (54) and a dichroic mirror (36) and the objective (38) of the heating beam (34) onto a spot at the heated spot of the sample (22). The probe beam (52) is reflected at an intensity that depends on the surface temperature and is deflected by an angle that depends on the integral of temperature beneath the surface. The reflected beam passes back to the splitter (54) where it is reflected to a split photodetector (80) from which the differential output indicates integral of temperature and sum output indicates surface temperature to a processor (58) determining thickness and compositional variables therefrom.
Inventors
- 👤 Allan Rosencwaig
- 👤 Jon Opsal
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:07
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/1702; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0658; G01N21/55; G01N25/00; G01N25/72; G01N21/21; G01N2201/00; G01N2201/10; G01N2201/108; G01N2201/1087
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
131 words
Apparatus for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal waves in a sample, said thermal waves being generated by a periodic localized heating at a spot on the surface of the sample, said apparatus comprising: first means for detecting thermal waves, said first means being of the type which generates output signals that are a function primarily of the surface temperature; second means for detecting thermal waves, said second means being of the type which generates output signals that are primarily a function of the integral of the temperature beneath the sample surface; and means for processing the output signals from said first and second detection means such that information about both layer thickness and compositional variables of the sample may be evaluated.
Claim 2
Dependent Claim
131 words
Apparatus for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal waves in a sample, said thermal waves being generated by a periodic localized heating at a spot on the surface of the sample, said apparatus comprising: first means for detecting thermal waves, said first means being of the type which generates output signals that are a function primarily of the surface temperature; second means for detecting thermal waves, said second means being of the type which generates output signals that are primarily a function of the integral of the temperature beneath the sample surface; and means for processing the output signals from said first and second detection means such that information about both layer thickness and compositional variables of the sample may be evaluated.
Claim 3
Dependent Claim
33 words
An apparatus as recited in claim 1 wherein said first detection means is defined by a means for monitoring the reflectivity changes at the sample surface as a result of the periodic heating.
Claim 4
Dependent Claim
68 words
An apparatus as recited in claim 2 wherein said first detection means comprises: a radiation probe; a means for directing the radiation probe on a portion of the periodically heated area on the sample surface in a manner such that the radiation probe reflects off the surface of the sample; and a means for measuring the intensity variations of the reflected radiation probe resulting from the periodic heating.
Claim 5
Dependent Claim
26 words
An apparatus as recited in claim 1 wherein said second detection means includes a means for detecting the acoustic waves which are produced in the sample.
Claim 6
Dependent Claim
34 words
An apparatus as recited in claim 1 wherein said second detection means is defined by a means for monitoring the angular changes of the sample surface within the area which has been periodically heated.
Claim 7
Dependent Claim
75 words
An apparatus as recited in claim 5 wherein said second detection means comprises: a radiation probe; means for directing said radiation probe on a portion of the periodically heated area on the sample surface in a manner such that said radiation probe reflects off the surface of the sample; and means for measuring the angular displacement of the reflected probe, said displacement resulting from the local angular changes in the surface conditions of the sample.
Claim 8
Dependent Claim
34 words
An apparatus as recited in claim 6 wherein said first detection means is defined by a means for measuring the reflectivity changes at the surface of the sample as result of the periodic heating.
Claim 9
Dependent Claim
31 words
An apparatus as recited in claim 7 wherein said first detection means includes a means arranged to measure the intensity variations of the reflected radiation probe of said second detection means.
Claim 10
Dependent Claim
39 words
An apparatus as recited in claim 8 wherein' the measuring means of both the first and second detection means includes a single photodetector capable of measuring both the angular displacements and the intensity variations of the reflected probe beam.
Claim 11
Dependent Claim
83 words
An apparatus as recited in claim 8 wherein said means for directing the radiation probe of said second detection means is arranged such that during the measurement of the angular displacements of the radiation probe, the radiation probe is directed on one-half of the periodically heated area on the surface of the sample and spaced from the center of the periodically heated area and during the measurement of reflectivity changes, the radiation probe is directed at the center of the periodically heated area.
Claim 12
Independent Claim
176 words
An apparatus for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal waves present in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said apparatus comprising: a radiation probe; means for directing the radiation probe within a portion of the periodically heated area on the sample surface in a manner such that the radiation probe reflects off the sample surface; first means for measuring the intensity variations of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the surface temperature of the sample? second means for measuring the angular displacements of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the integral of the temperature beneath the sample surface; and means for processing the output signals from said first and second measuring means such that information about both layer thickness and compositional variables of the sample may be - evaluated.
Claim 13
Independent Claim
176 words
An apparatus for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal waves present in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said apparatus comprising: a radiation probe; means for directing the radiation probe within a portion of the periodically heated area on the sample surface in a manner such that the radiation probe reflects off the sample surface; first means for measuring the intensity variations of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the surface temperature of the sample? second means for measuring the angular displacements of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the integral of the temperature beneath the sample surface; and means for processing the output signals from said first and second measuring means such that information about both layer thickness and compositional variables of the sample may be - evaluated.
Claim 14
Dependent Claim
20 words
An apparatus as recited in claim 11 wherein said first and second measuring means are defined by a single photodetector.
Claim 15
Dependent Claim
83 words
An apparatus as recited in claim 12 wherein said means for directing the radiation probe of said second detection means is arranged such that during the measurement of the angular displacements of the radiation probe, the radiation probe is directed on one-half of the periodically heated area on the surface of the sample and spaced from the center of the periodically heated area and during the measurement of reflectivity changes, the radiation probe is directed at the center of the periodically heated area.
Claim 16
Independent Claim
124 words
A method for evaluating the thickness and compositional variables in a layered or thin film sample by analyzing thermal waves present in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said method comprising the steps of: A. detecting thermal wave signals within the periodically heated area on the surface of the sample that are a function primarily of the surface temperature; B . detecting thermal wave signals within the periodically heated area on the surface of the sample that are primarily a function of the integral of the temperature beneath the sample; - and C. processing the measured thermal wave signals such that information about both layer thickness and compositional variables may be evaluated.
Claim 17
Independent Claim
124 words
A method for evaluating the thickness and compositional variables in a layered or thin film sample by analyzing thermal waves present in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said method comprising the steps of: A. detecting thermal wave signals within the periodically heated area on the surface of the sample that are a function primarily of the surface temperature; B . detecting thermal wave signals within the periodically heated area on the surface of the sample that are primarily a function of the integral of the temperature beneath the sample; - and C. processing the measured thermal wave signals such that information about both layer thickness and compositional variables may be evaluated.
Claim 18
Dependent Claim
39 words
15 . A method as recited in claim 14 wherein the detection of thermal wave signals recited in Step A is performed by measuring the periodic reflectivity changes at the sample surface as a result of the periodic heating.
Claim 19
Dependent Claim
74 words
A method as recited in claim 15 wherein said step of monitoring the periodic reflectivity changes at the sample surface is performed by the following steps: directing a radiation probe on a portion of the periodically heated area on the surface of the sample in a manner such that the radiation probe reflects off the surface of the sample; and measuring the intensity variations of the reflected radiation probe resulting from said periodic heating.
Claim 20
Dependent Claim
31 words
A method as recited in claim 14 wherein said detection of thermal wave signals recited in Step B is performed by measuring the acoustic waves which are produced in the sample.
Claim 21
Dependent Claim
39 words
An apparatus as recited in claim 14 wherein the step of detecting thermal wave signals recited in Step B is performed by measuring the periodic angular changes of the sample surface within the area which has been periodically heated.
Claim 22
Dependent Claim
76 words
A method as recited in claim 18 wherein said step of monitoring the periodic angular changes of the sample surface comprises the following steps: focusing a radiation probe on a portion of the periodically heated area on the sample surface such that the radiation probe reflects off the surface of the sample; and measuring the angular displacements of the reflected probe, said displacements resulting from the local angular changes in the surface conditions of the sample.
Claim 23
Dependent Claim
44 words
A method as recited in claim 19 wherein said step of detecting the thermal wave signals recited in Step A of claim 14 is performed by measuring the periodic reflectivity changes at the surface of the sample as a result of the periodic heating.
Claim 24
Dependent Claim
38 words
A method as recited in claim 20 wherein said step of measuring the reflectivity changes of the surface of the sample is performed by measuring the intensity variations of the reflected radiation probe resulting from the periodic heating.
Claim 25
Independent Claim
163 words
A method for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal wave signals in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said method comprising the steps of: A. directing a radiation probe within a portion of the periodically heated area on the sample surface in a manner such that the radiation probe reflects off the sample surface; B. measuring the periodic intensity variations of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the surface temperature; C. measuring the periodic angular displacements of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the integral of the temperature beneath the sample; and D. processing the output signals measured in Steps B and C to derive information about both layer thickness and compositional variables of the sample.
Claim 26
Independent Claim
163 words
A method for evaluating thickness and compositional variables in a layered or thin film sample by analyzing thermal wave signals in the sample, said thermal waves being generated by a periodic localized heating at the surface of the sample, said method comprising the steps of: A. directing a radiation probe within a portion of the periodically heated area on the sample surface in a manner such that the radiation probe reflects off the sample surface; B. measuring the periodic intensity variations of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the surface temperature; C. measuring the periodic angular displacements of the reflected radiation probe resulting from the periodic heating and generating output signals that are primarily a function of the integral of the temperature beneath the sample; and D. processing the output signals measured in Steps B and C to derive information about both layer thickness and compositional variables of the sample.
Claim 27
Dependent Claim
37 words
A method as recited in claim 22 wherein during said step of measuring the intensity variations of the reflected probe beam, the radiation probe is directed to be coincident with the center of the periodically heated area.
Claim 28
Dependent Claim
43 words
A method as recited in claim 22 wherein during the step of measuring the angular displacements of the reflected radiation probe, the radiation probe is directed on one-half of the periodically heated area and spaced from the center of the periodically heated area.
References Cited (Backward Citations)
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