Patent Application 18501672 - OPTICAL SENSOR FOR FILM THICKNESS MEASUREMENT - Rejection
Patent Application 18501672 - OPTICAL SENSOR FOR FILM THICKNESS MEASUREMENT
Title: OPTICAL SENSOR FOR FILM THICKNESS MEASUREMENT
Application Information
- Invention Title: OPTICAL SENSOR FOR FILM THICKNESS MEASUREMENT
- Application Number: 18501672
- Submission Date: 2025-05-15T00:00:00.000Z
- Effective Filing Date: 2023-11-03T00:00:00.000Z
- Filing Date: 2023-11-03T00:00:00.000Z
- National Class: 356
- National Sub-Class: 630000
- Examiner Employee Number: 79577
- Art Unit: 2877
- Tech Center: 2800
Rejection Summary
- 102 Rejections: 1
- 103 Rejections: 3
Cited Patents
The following patents were cited in the rejection:
Office Action Text
DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 101
35 U.S.C. 101 reads as follows:
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.
Claims 1-15 are rejected under 35 U.S.C. 101 because the claimed invention is directed to an abstract idea without significantly more. The claim(s) recite(s) limitations directed to a method of determining the thickness of layers from a reflectivity spectrum. The limitations in the claims are directed to using mathematical concepts including: determining a first thickness of the top layer by applying a top-layer model which is unaffected by a plurality of semiconductor structures (claim 1) performing a Fourier Transform (FT) to obtain an FT spectrum (claim 2), selecting which portions of the reflectivity spectrum to use to perform the FT (claims 3-4, 6-7), identifying peaks in the FT spectrum to use to determine the thickness (claim 5), calibrating a location of the peak in the FT spectrum (claim 8), scaling the FT spectrum (claim 9), creating a ratio of reflectivities to obtain the reflectivity spectrum (claim 10), determining a critical wavelength of the ratio (claims 11-12), and determining a plurality of thicknesses of the top layer at several regions (claims 13-14). The claims recite the judicial exception of an abstract idea of determining and performing mathematical operations which falls within the category of “mathematical concepts” ( See MPEP 2106.04(a)(2)). The “mathematical concepts” abstract idea grouping is defined as mathematical relationships, mathematical formulas or equations, mathematical calculations. The claims’ limitations are considered mathematical concepts because they correspond to a mathematical relationship and performing a mathematical calculation.
This judicial exception is not integrated into a practical application. The claims disclose additional steps of: illuminating a sample with semiconductor structures with a broadband light source (claims 1, 13), collecting at least two reflected beams (claim 10), repositioning the sample or beam (claim 13), and discloses that the top layer comprises a semiconductor material, and the broadband light has a wavelength range of 200-1000nm (claim 15). However, these limitations appear to only add insignificant extra-solution activity, such as data gathering, for use in the judicial exception, and only generally links the use of the judicial exception to the particular technological environment of measuring the thickness of a semiconductor substrate layer using broadband illumination with a high level of generality.
The claims do not include additional elements that are sufficient to amount to significantly more than the judicial exception because these are well-understood, conventional activities previously known to the industry, recited at a high level of generality. The use of a machine that contributes only nominally or insignificantly to the execution of the claimed method (e.g., in a data gathering step or in a field-of-use limitation) would not integrate a judicial exception or provide significantly more. See Bilski, 561 U.S. at 610, 95 USPQ2d at 1009 (citing Parker v. Flook, 437 U.S. 584, 590, 198 USPQ 193, 197 (1978)), and CyberSource v. Retail Decisions, 654 F.3d 1366, 1370, 99 USPQ2d 1690 (Fed. Cir. 2011).
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claim(s) 1-9, 12, 15-16 and 18 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Aizenberg (2013/0050687).
In regards to claim 1, Aizenberg teaches a method of film thickness measurement (abstract and fig. 1a), the method comprising: illuminating a top layer of a sample in a first region with a broadband illumination beam (via 30, ⁋ 23 “outputs a broad band light”), the sample including a substrate and a plurality of semiconductor structures formed between the substrate and the top layer (⁋ 6 discloses the sample is a semiconductor, and ⁋ 45 discloses the substrate of the sample has several layers grown on top of each other; in the example layers 3 and 2 would be considered the plurality of semiconductor structures formed between the substrate and top layer); obtaining a first reflectivity spectrum of the sample in the first region (via 40, ⁋ 27); and determining a first thickness of the top layer in the first region by applying a top- layer model to the first reflectivity spectrum (⁋s 28-31), wherein the top-layer model is substantially unaffected by the plurality of semiconductor structures (⁋ 31, fig. 5, wherein peaks in the optical thickness domain are only associated with a single layer, and are thus unaffected by the other layers).
In regards to claim 2, Aizenberg teaches wherein applying the top-layer model comprises: performing a Fourier Transform (FT) of the first reflectivity spectrum to obtain an FT spectrum; and determining the first thickness based on a primary peak of the FT spectrum which has a highest intensity in the FT spectrum (as can be seen in fig. 3b, and ⁋ 36).
In regards to claims 3-4, the FT is performed for at least a first portion of the first reflectivity spectrum substantially unaffected by the plurality of semiconductor structures and a second portion of the first reflectivity spectrum which is affected by the plurality of semiconductor structures (as discussed in ⁋ 36, the FT is performed for the entire reflectivity spectrum).
In regards to claim 5, the FT spectrum further comprises a secondary peak that is affected by the plurality of semiconductor structures (the smaller peaks shown in fig. 3B, for example), the primary peak is substantially unaffected by the plurality of semiconductor structures (as discussed in ⁋ 36), and the first thickness is determined based on the primary peak of the FT spectrum and not based on the secondary peak so that the top-layer model is substantially unaffected by the plurality of semiconductor structures (⁋s 6, 34-36).
In regards to claim 6, Aizenberg teaches, prior to determining the first thickness of the top layer, truncating a second portion of the first reflectivity spectrum which is affected by the plurality of semiconductor structures (⁋ 36 and 42, the peaks 250, 260, and 270 are selected which are not affected by the plurality of structures to subsequently calculate the thickness of the layer, and therefore the rest of the spectrum is truncated).
In regards to claim 7, Aizenberg teaches truncating a first portion below a critical wavelength (fig. 3B and ⁋ 42, wherein smaller peaks below peaks 260 and 270 are ignored).
In regards to claim 8, the method further comprises calibrating a location of the primary peak of the FT spectrum versus the first thickness experimentally or computationally (⁋ 28).
In regards to claim 9, the method further comprises scaling a horizontal axis of the FT spectrum with n and k, which are complex refractive indices of the top layer, to obtain a scaled FT spectrum so that the location of the primary peak of the scaled FT spectrum is independent of n and k (⁋s 41-43).
In regards to claim 12, the first reflectivity spectrum of the sample is a reflectivity coefficient spectrum, and the method further comprises determining a critical wavelength which is a boundary between two regimes of the reflectivity coefficient spectrum (⁋ 42).
In regards to claim 15, the top layer comprises a semiconductor material (⁋ 6 discloses the sample is a semiconductor, and ⁋ 45 discloses the substrate of the sample has several layers grown on top of each other), and the broadband illumination beam has a wavelength range of 200-1000 nm (⁋ 23 discloses a halogen lamp, which falls in the range of 200-1000nm).
In regards to claim 16, Aizenberg teaches an apparatus (abstract and fig. 1a), comprising: a handling stage configured to receive a sample (60 receives sample 50), the sample comprising a substrate, a top layer and a plurality of semiconductor structures formed between the substrate and the top layer (⁋ 6 discloses the sample is a semiconductor, and ⁋ 45 discloses the substrate of the sample has several layers grown on top of each other; in the example layers 3 and 2 would be considered the plurality of semiconductor structures formed between the substrate and top layer); a light source configured to emit a broadband illumination beam (30 and ⁋ 23); optics configured to guide the broadband illumination beam to illuminate the top layer of the sample, collect a reflected beam from the top layer and guide the reflected beam (⁋ 23 discloses fiber optics and lenses to direct the illumination beam to the sample, and a to collect the reflected beam) to an optical detector that is configured to obtain a reflectivity spectrum of the sample (40); and a controller configured to determine a thickness of the top layer by applying a top- layer model to the reflectivity spectrum (22 and ⁋s 28-31), wherein the top-layer model is substantially unaffected by the plurality of semiconductor structures (⁋ 31, fig. 5, wherein peaks in the optical thickness domain are only associated with a single layer, and are thus unaffected by the other layers).
In regards to claim 18, the optics includes at least one selected from the group consisting of an optical fiber, a collection lens, a system stop aperture, and a polarizer (⁋ 23).
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 13-14 and 19-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Aizenberg (2013/0050687).
In regards to claim 13, Aizenberg discloses the method of claim 1, as disclosed above. Further, Aizenberg discloses repositioning the sample, the broadband illumination beam, or a combination thereof (via fig. 1a, 60, ⁋ 23 and 35); and determining a two-dimensional representation of thickness of a layer by applying the top layer model (⁋ 35 wherein the physical characteristic includes a thickness as discussed in ⁋ 31). Aizenberg is silent to the specifics of how this scanning is performed. However, the examiner takes official notice that the method of repositioning the sample to a second region, illuminating the second region, obtaining a second reflectivity spectrum and determining a thickness based on this reflectivity spectrum is well known process in the art, and would be done in order to create the two-dimensional representation of the thickness across the layer, as described by Aizenberg. Therefore, it would be obvious to one of ordinary skill in the art to, after repositioning the sample, illuminating the top layer of the sample in a second region with the broadband illumination beam; obtaining a second reflectivity spectrum of the sample in the second region; and determining a second thickness of the top layer in the second region by applying the top-layer model to the second reflectivity spectrum as it is well known in the art to do this, and in order to create the two-dimensional representation of thickness of a layer as described by Aizenberg.
In regards to claim 14, Aizenberg discloses scanning a sample in a pattern to determine a plurality of thicknesses of the top layer in a plurality of regions across at least a fraction of the sample (⁋ 35 wherein the physical characteristic includes a thickness as discussed in ⁋ 31). Aizenberg is silent to the pattern that is used to scan the sample; however, it is noted that the pattern scanned over a sample is merely a matter of design choice as it would not modify the operation of the device, and would be selected based on such things as the shape of the sample. Therefore, it would be obvious to one of ordinary skill in the art to scan using either an XY pattern or an RӨ pattern, as a matter of design choice and in order to determine a plurality of thicknesses of the top layer in a plurality of regions across at least a fraction of the sample in a particular pattern based on the shape of the sample.
In regards to claim 19, Aizenberg teaches the apparatus of claim 16, as discussed above. Further the apparatus includes a handling stage which translates (fig. 1a, 60 and ⁋ 24 and 35), and the light source consists of a laser, a laser diode, a light emitting diode, a gas discharge light source, and a laser-driven light source (⁋ 24). Aizenberg is silent to the stage being an X-Y, X-Y-Z, R-0, or R-O-Z stage. However, the examiner takes official notice that these kinds of stages are very well-known in the art, and are used to translate a sample in a specific manner in order to do 2-dimensional measurements, as discussed by Aizenberg. Therefore, it would be obvious to one of ordinary skill in the art to have the stage of Aizenberg be an X-Y, X-Y-Z, R-0, or R-O-Z stage, as these are well-known type of stages, and in order to allow the sample to be translated in a particular manner in order to make a 2-dimensional measurement, as discussed by Aizenberg.
In regards to claim 20, Aizenberg discloses that a surface treatment is performed on the sample (⁋ 45-46 wherein a growth process is a surface treatment), but is silent to a processing chamber. However, the examiner takes official notice that a processing chamber is well-known to be used in order to grow layers onto a semiconductor sample, as described by Aizenberg. Therefore, it would be obvious to one of ordinary skill in the art to include into Aizenberg a processing chamber, as it is well-known in the art, and in order to allow the growth process as described to be performed in an controlled and safe manner.
Claim(s) 10-11 is/are rejected under 35 U.S.C. 103 as being unpatentable over Aizenberg (2013/0050687) as applied to claim 1 above, and further in view of Park et al. (2015/0029517).
In regards to claim 10, Aizenberg discloses the method of claim 1, as discussed above. Aizenberg is silent to collecting at least two reflected beams of substantially orthogonal polarizations; and obtaining the first reflectivity spectrum as a ratio of reflectivities collected at the at least two reflected beams.
Park, in the same field of endeavor as Aizenberg of thickness measurement of a thin film (abstract), discloses collecting at least two reflected beams of substantially orthogonal polarizations; and obtaining the first reflectivity spectrum as a ratio of reflectivities collected at the at least two reflected beams (⁋ 38-41). Park discloses that this method allows for measuring thickness of a thin film including more complicated patterns (⁋ 6). Therefore, it would be obvious to one of ordinary skill in the art to include into Aizenberg the steps of collecting at least two reflected beams of substantially orthogonal polarizations; and obtaining the first reflectivity spectrum as a ratio of reflectivities collected at the at least two reflected beams as taught by Park, in order to allow for measuring thickness of a thin film including more complicated patterns.
In regards to claim 11, the combination teaches determining the critical wavelength at which the ratio starts to be different from unity (⁋ 41-42 and fig. 9 graphs psi which is related to the ratio of s and p polarization; as this claim merely discloses determining the wavelength, and the combination graphs the relationship, this is enough to determine the critical wavelength at which the ratio starts to be different).
Claim(s) 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Aizenberg (2013/0050687) in view of Davidson (2010/0195112).
In regards to claim 17, Aizenberg teaches the apparatus of claim 16, as discussed above. Aizenberg is silent to the optics comprising a Schwarzschild objective and a knife edge prism (KEP), wherein: the Schwarzschild objective includes a primary mirror and a secondary mirror, the KEP has a first side and a second side, the Schwarzschild objective and the KEP are configured so that the broadband illumination beam is directed by the first side of the KEP to go through an aperture of the primary mirror to the secondary mirror, reflected to the primary mirror, and then reflected to the top layer of the sample, and the Schwarzschild objective and the KEP are configured so that the reflected beam from the top layer is reflected by the primary mirror to the secondary mirror, reflected to go through the aperture of the primary mirror to the second side of the KEP, and then directed to the optical detector. However, Aizenberg discloses the measurement apparatus generally, and mentions that the measurement could be performed by other means (⁋ 22). Further, the examiner takes official notice that Schwarzschild objectives are well-known and used to reduce chromatic aberration.
For example, Davidson, in the same field of optically measuring a thickness (⁋ 128), discloses an apparatus comprising a Schwarzschild objective (fig. 1, 110, ⁋ 93) and a beamsplitters (125), wherein the Schwarzschild objective includes a primary mirror (110) and a secondary mirror (201), the beamsplitter has a first side (facing the source 132) and a second side (facing the objective), the Schwarzschild objective and the beamsplitter are configured so that the broadband illumination beam (from 132) is directed by the first side of the beamsplitter to go through an aperture of the primary mirror (110) to the secondary mirror (201), reflected to the primary mirror (as can be seen in fig. 1), and then reflected to the top layer of the sample (105), and the Schwarzschild objective and the beamsplitter are configured so that the reflected beam from the top layer is reflected by the primary mirror (110) to the secondary mirror (201), reflected to go through the aperture of the primary mirror to the second side of the beamsplitters (side facing the objective 110), and then directed to the optical detector (162 and 164). Therefore, it would be obvious to one of ordinary skill in the art to replace the optical system of Aizenberg with the optical system of Davidson, including the Schwarzschild objective and beamsplitters in the configuration as described above, in order to have an alternate configuration of optical parts to use for thickness measurements, and in order to have an objective that helps reduce chromatic aberration in the measurement signal.
The combination is silent to the system having a knife edge prism (KEP). However, the examiner takes official notice that KEPs (also known as right-angle prisms) are very well known in the art as a means to direct light, and it would be obvious to one of ordinary skill in the art to replace the beam splitter of the combination with a KEP in order to allow more flexibility in the design of the optical system, allowing for a folding beam path from the objective to the detector.
Conclusion
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/KARA E. GEISEL/
Art Unit 2877