US5452953A
Expired / Lapsed
US
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Film thickness measurement of structures containing a scattering surface
Assignee: ADE Corp
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Filing: 1993-10-12
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Granted: 1995-09-26
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Expires: 2013-10-12
Abstract
Abstract Systems for making thickness measurements in a thin film structure using an incoherently or coherently coupled structured surface. A system is used to measure the thickness of a thin film layer of a thin film structure in which polished and structured surfaces are coherently coupled together. Visible light used to measure the thickness of thin bonded wafers that have a ground upper surface, or infrared light is used to measure the thickness of thick silicon wafers where one surface is ground, and the other is polished. Other systems use a structured surface that is incoherently coupled to a thin film structure in order to illuminate the thin film structure at many angles. The systems produce interference fringes that are detected and recorded, and multispectral pattern matching is used in a computer to compute film thickness based on scattering characteristics included in a library f stored interference patterns.
Inventors
- 👤 Anthony M. Ledger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:32
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/06; G01B11/0616; G01B11/0625
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
103 words
A film thickness measuring system for measuring the thicknesses of a thin film structure, said system comprising: a scattering surface on or in proximity to a surface of the thin film structure; a spectrally filtered light source for illuminating the thin film structure to produce a reflectively scattered beam therefrom; a detector system for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that correspond to respective thicknesses of the thin film structure.
Claim 2
Dependent Claim
103 words
A film thickness measuring system for measuring the thicknesses of a thin film structure, said system comprising: a scattering surface on or in proximity to a surface of the thin film structure; a spectrally filtered light source for illuminating the thin film structure to produce a reflectively scattered beam therefrom; a detector system for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that correspond to respective thicknesses of the thin film structure.
Claim 3
Dependent Claim
45 words
The film thickness measuring system of claim 1 wherein the detector system comprises: a detector for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a frame grabber coupled to the detector for capturing the output signal produced by the detector.
Claim 4
Dependent Claim
47 words
The film thickness measuring system of claim 1 wherein the scattering surface comprises: an outer thin film layer that has a ground outer surface over a substrate and a first thin film layer of a wafer that forms a coherent structured outer scattering surface of the wafer.
Claim 5
Dependent Claim
69 words
The film thickness measuring system of claim 1 wherein the thin film structure comprises a partially polished thin film structure, and wherein the scattering surface comprises a structured surface disposed between the thin film structure and the spectrally filtered light source, and disposed adjacent to the thin film structure at a distance greater than the coherence length (L) for the radiation provided by the spectrally filter in light source.
Claim 6
Dependent Claim
24 words
The film thickness measuring system of claim 4 wherein the plurality of library models are determined by characterizing the structured surface as a beamsplitter.
Claim 7
Dependent Claim
31 words
The film thickness measuring system of claim 4 wherein the structured surface is selected from the group consisting of a fly's eye, lenslet arrays, binary optical elements or diffractive patterned elements.
Claim 8
Dependent Claim
31 words
The film thickness measuring system of claim 4 wherein the structured surface is selected from the group consisting of a fly's eye, lenslet arrays, binary optical elements or diffractive patterned elements.
Claim 9
Dependent Claim
17 words
The film thickness measuring system of claim 1 wherein the thin film structure comprises a bonded wafer.
Claim 10
Dependent Claim
17 words
The film thickness measuring system of claim 1 wherein the thin film structure comprises a coated wafer.
Claim 11
Dependent Claim
92 words
Apparatus comprising: a thin film structure; a scattering surface on or in proximity to a surface of the thin film structure; a spectrally filtered light source for illuminating the thin film structure to produce a reflectively scattered beam therefrom; a detector system for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that correspond to respective thicknesses of the thin film structure.
Claim 12
Dependent Claim
92 words
Apparatus comprising: a thin film structure; a scattering surface on or in proximity to a surface of the thin film structure; a spectrally filtered light source for illuminating the thin film structure to produce a reflectively scattered beam therefrom; a detector system for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that correspond to respective thicknesses of the thin film structure.
Claim 13
Dependent Claim
45 words
The film thickness measuring system of claim 10 wherein the detector system comprises: a detector for detecting the reflectively scattered beam and providing an output signal corresponding thereto; and a frame grabber coupled to the detector for capturing the output signal produced by the detector.
Claim 14
Dependent Claim
53 words
The film thickness measuring system of claim 10 wherein the thin film structure comprises: a multilayer thin film structure comprising a wafer that includes a substrate, a first thin film layer, and an outer thin film layer that has a ground outer surface that forms a coherent structured outer surface of the wafer.
Claim 15
Dependent Claim
68 words
The film thickness measuring system of claim 10 wherein the thin film structure comprises a partially polished thin film structure, and wherein the scattering surface comprises a structured surface disposed between the thin film structure and the spectrally filtered light source, and disposed adjacent to the thin film structure at a distance greater than the coherence length (L) for the radiation provided by the spectrally filtered light source.
Claim 16
Dependent Claim
24 words
The film thickness measuring system of claim 13 wherein the plurality of library models are determined by characterizing the structured surface as a beamsplitter.
Claim 17
Dependent Claim
17 words
The film thickness measuring system of claim 10 wherein the thin film structure comprises a bonded wafer.
Claim 18
Dependent Claim
17 words
The film thickness measuring system of claim 10 wherein the thin film structure comprises a coated wafer.
Claim 19
Independent Claim
108 words
A method measuring the thickness of a thin film structure comprising the steps of: providing a scattering surface on or in proximity to a surface of the thin film structure; providing a spectrally filtered light source to illuminate the thin film structure such that a reflectively scattered beam is produced therefrom; providing a detector system to detect the reflectively scattered beam and to provide an output signal corresponding thereto; and providing a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that corresponds to the respective thicknesses of the thin film structure.
Claim 20
Independent Claim
108 words
A method measuring the thickness of a thin film structure comprising the steps of: providing a scattering surface on or in proximity to a surface of the thin film structure; providing a spectrally filtered light source to illuminate the thin film structure such that a reflectively scattered beam is produced therefrom; providing a detector system to detect the reflectively scattered beam and to provide an output signal corresponding thereto; and providing a computer coupled to the detector system that comprises a library including a plurality of models corresponding to scattering patterns from the reflectively scattered beam, and that corresponds to the respective thicknesses of the thin film structure.
Claim 21
Dependent Claim
43 words
The method of claim 17 wherein the thin film structure comprises a wafer that includes a substrate, a first thin film layer, and an outer thin film layer having a ground outer surface that forms a coherent structured outer surface of the wafer.
Claim 22
Dependent Claim
51 words
The method of claim 18 wherein the scattering surface comprises a structured surface disposed between the thin film structure and the spectrally filtered light source, and disposed adjacent to the thin film structure at a distance greater than the coherence length for the radiation provided by the spectrally filtered light source.
Claim 23
Dependent Claim
21 words
The method of claim 19 wherein the plurality of library models are determined by characterizing the structured surface as a beamsplitter.
Claim 24
Dependent Claim
28 words
The method of claim 19 wherein the structured surface is selected from the group consisting of a fish's eye, lenslet arrays, binary optical elements or diffractive patterned elements.
References Cited (Backward Citations)
US3631526A
Cited
US3693025A
Cited
US3870884A
Cited
US4254337A
Cited
JPH02115704A
Cited
JPH05113319A
Cited
US5293214A
Cited
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