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 .
This action is responsive to the initial filing of 7/19/2026.
Claim Rejections - 35 USC § 103
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) 1-6 and 11-18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Huang (US Patent Publication 20200033117) in view of Schulte (US Patent Publication 20220221269).
Regarding claim 1, Huang teaches an apparatus for interferometric determination of a property of a shape of a test surface of an object under test, comprising:
- an irradiation source configured to generate an input wave (FIG. 2B, illumination source 104, described in paragraph 40 and elsewhere),
- a wave splitter (FIG. 2B, prism chuck 110, which includes one or more shearing prisms as described in paragraph 46) configured to generate, from the input wave, two plane waves with parallel directions of propagation and with an offset from one another across the parallel directions of propagation (FIG. 2B, collimated beamlets 105a and 105b, which both travel in parallel to the sample 103. Note that collimated beams have planar waves), and
- a detector configured to capture at least one interferogram generated by superposition of the two measurement waves following their interaction with the test surface (FIG. 2B, detector assembly 120).
The planar collimated beamlets 105a and 105b of Huang are already adapted to generate two measurement waves by respectively adapting wavefronts of the two plane waves with an offset from one another to a target shape of the test surface (see paragraph 33), so Huang does not teach a separate wavefront adaptor to provide such a configuration.
In the same field of endeavor of interferometric surface metrology, Schulte does teach a separate wavefront adaptor (FIG. 1, diffractive structure pattern 64, described in paragraph 65 as a computer-generated hologram) configured to generate measurement waves (FIG. 1, test wave 66, described in paragraph 66) by adapting wavefronts of plane waves to a target shape of a test surface (paragraph 20). By using a wavefront adaptor in the form of a computer-generated hologram, Schulte is able to measure the shape of a curved surface in a way that still has the wavefronts of the measurement light substantially perpendicularly incident on different regions of the surface (paragraph 20).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the interferometric apparatus of Huang with the computer-generated hologram of Schulte to adapt the wavefronts of the measurement light to a curved target shape for use on intentionally curved samples, with predictable results and a reasonable expectation of success.
Regarding claim 2, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the apparatus is configured such that the two measurement waves, following their interaction with the test surface and prior to incidence on the detector, pass through the wave splitter in a direction opposite to a direction radiation of the input wave passes through the wave splitter, and the two measurement waves are offset toward one another due to passing through the wave splitter (paragraph 30 describes the beam being recombined after reflecting from the sample 103).
Regarding claim 3, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches an evaluator configured to ascertain at least a derivative of the shape of the test surface using the at least one interferogram (FIG. 2B, controller 122, also see paragraph 7, final sentence, noting that “derivative” is a term for a slope).
Regarding claim 4, Huang, as modified by Schulte, teaches the apparatus of claim 3 (as described above).
Huang further teaches that the evaluator is configured to ascertain derivatives of the shape of the test surface at a plurality of locations on the test surface (FIG. 2B, note that the beamlets 105a and 105b collectively cover the entire area of the sample 103 that is shown in the figure, which would include a plurality of points) and determine the shape of the test surface by integrating the derivatives (Paragraph 4 references measuring sample warp using integration. Paragraph 36 notes that the any phase retrieval algorithm known in the art may be used and does not exclude methods that might be difficult to implement or inefficient).
Regarding claim 5, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the apparatus is configured to vary a splitting direction of the two plane waves (paragraph 53, rotating prism chuck 110 using a rotational stage).
Regarding claim 6, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the wave splitter comprises a beam direction splitter (FIG. 2B, prism chuck 110) and a direction matcher (FIG. 2B, collimator 112), the beam direction splitter being configured to generate two intermediate waves (FIG. 2B, the two diverging beams (one in solid lines and the other in dotted lines) going from prism chuck 110 to collimator 112) with different directions of propagation (FIG. 2B, note that the dotted- and solid-line beams are centered in different positions on collimator 112) from the input wave and the direction matcher being configured to generate the two plane waves by matching directions of propagation of the two intermediate waves to one another (FIG. 2B, note that collimated beamlets 105a and 105b are parallel).
Regarding claim 11, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
Huang further teaches that the beam direction splitter and/or the direction matcher is configured as a shearing prism (paragraph 45 states that prism chuck 110 includes one or more shearing prisms).
Regarding claim 12, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
While Huang does not explicitly teach that the direction matcher is configured as a shearing prism which is arranged with reversed orientation vis-a-vis a shearing prism of a same type serving as the beam direction splitter, Huang does teach that the collimator 112 may include any collimator or collimating optical elements known in the art (paragraph 30), and does teach shearing prisms which can be used in that capacity (Consider the Wollaston prism of FIG. 4. With the direction of propagation of light reversed, the two beams would be combined into a single beam. If the locations on the prism at which the o-beam and the e-beam are incident are displaced relative to each other vertically (for example, due to the beams having propagated apart after being separated by another Wollaston prism), then the outgoing beam would take the form of two parallel beams, like beamlets 105a and 105b in FIG. 2B.). By using a second shearing prism to collimate the beams, Huang could provide a different means of collimating the beamlets without needing an additional lens.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte, with a second shearing prism as the direction matcher of the same type used as the beam direction splitter by Huang, with predictable results and a reasonable expectation of success.
Regarding claim 13, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
Huang further teaches that the beam direction splitter (shearing prism 130, shown in detail in FIG. 3 as a Rochon prism) is configured to split off a second intermediate wave of the two intermediate waves from the input wave (FIG. 3, e-beam 105a), with a first intermediate wave of the two intermediate waves being a portion of the input wave passing through the beam direction splitter without deflection (FIG. 3, o-beam 105b).
Regarding claim 14, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
Huang further teaches that directions of propagation of the two intermediate waves are oriented symmetrically with respect to a direction of propagation of the input wave (FIG. 4, shearing prism 130 splits the e-beam 105a and the o-beam 105b upward and downward, symmetrically relative to the original path of the single incoming beam 101).
Regarding claim 15, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
While Huang does teach tuning the interferometer by mechanically actuation of the shearing prism 130 (paragraph 35), Huang only goes into detail of that mechanical actuation in ways other than to modify a distance between the beam direction splitter and the direction matcher, such as laterally translating the shearing prism (paragraph 57). Note, however, that in FIG. 2B, the extent to which beamlets 105a and 105b can diverge from each other is proportional to the distance between the prism chuck 110 and collimator 112, so mechanical actuation of the shearing prism 110 would also tune the relative offset between the beamlets 105a and 105b.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte, by translating optical components so as to tune the offset of the beamlets by tuning the distance between the prism chuck 110 and the collimator 112, with predictable results and a reasonable expectation of success.
Regarding claim 16, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the wave splitter comprises a shearing prism (FIG. 3 or FIG. 4, shearing prism 130).
While Huang is not especially specific regarding whether the shearing prism 130 (part of the prism chuck 110 in FIG. 2B) is plate shaped, FIG. 2B of Huang does depict the part that contains shearing prism as being substantially thin in the axial direction, which falls into the broadest reasonable interpretation of plate shaped.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte, by adopting the plate-shaped shearing prism depicted by FIG. 2B of Huang as a particular way of shearing the incoming optical beam,
Regarding claim 17, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the apparatus is configured to measure a mirror for EUV microlithography as object under test (paragraph 7, the apparatus measures light reflected from the sample, which indicates that it is compatible with use measuring such a mirror. Note that this claim does not limit the apparatus beyond that level of compatibility, as, in general, the material or article worked upon does not limit apparatus claims. See MPEP 2115.).
Regarding claim 18, Huang teaches a method for interferometric determination of a property of a shape of a test surface of an object under test, comprising:
- generating two plane waves with two parallel directions of propagation, which are offset from one another across the two parallel directions propagation (FIG. 2B, beamlets 105a and 105b), by splitting an input wave (FIG. 2B, using at least one shearing prism 130 included in prism chuck 110 and collimator 112),
- generating two measurement waves from the two plane waves of the two plane waves with an offset from one another (FIG. 2B, note the lateral offset between the beamlets 105a and 105b), and
- generating at least one interferogram by superposition of the two measurement waves following their interaction with the test surface and capturing the at least one interferogram (FIG. 2B, detector assembly 120).
The planar collimated beamlets 105a and 105b of Huang are already adapted to a target shape of the test surface (see paragraph 33), so Huang does not teach a separate step of adapting respective wavefronts to a target shape of the test surface
In the same field of endeavor of interferometric surface metrology, Schulte does teach a separate step of adapting respective wavefronts (FIG. 1, diffractive structure pattern 64, described in paragraph 65 as a computer-generated hologram) to a target shape of the test surface (paragraph 20). By using a wavefront adaptor in the form of a computer-generated hologram, Schulte is able to measure the shape of a curved surface in a way that still has the wavefronts of the measurement light substantially perpendicularly incident on different regions of the surface (paragraph 20).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the interferometric method of Huang with the computer-generated hologram of Schulte to adapt the wavefronts of the measurement light to a curved target shape for use on intentionally curved samples, with predictable results and a reasonable expectation of success.
Claim(s) 7-10 is/are rejected under 35 U.S.C. 103 as being unpatentable over Huang (US Patent Publication 20200033117) in view of Schulte (US Patent Publication 20220221269), further in view of Paschotta (Non-Patent Literature “Diffractive Optics”).
Regarding claim 7, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
Huang does not explicitly teach that the beam direction splitter and/or the direction matcher is configured as a diffractive optical element.
In the same field of endeavor of manipulating beams of light, Paschotta does teach that the beam direction splitter and/or the direction matcher is configured as a diffractive optical element (section “Periodic Diffraction Gratings”, diffractive beam splitters, which would split an incoming beam into at least two directions). By using diffractive optical elements, Paschotta is able to split beams with a well-defined distribution of optical powers (section Diffractive Micro-optics, paragraph 2).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte, with the diffractive beam splitter of Paschotta as an alternative way to split a beam, with predictable results and a reasonable expectation of success.
Regarding claim 8, Huang, as modified by Schulte, teaches the apparatus of claim 7 (as described above).
Huang does not explicitly teach that the beam direction splitter and/or the direction matcher is respectively configured to diffract incoming radiation only into a zeroth order of diffraction and, in terms of absolute value, first order of diffraction.
In the same field of endeavor of manipulating beams of light, Paschotta does teach that the beam direction splitter and/or the direction matcher is respectively configured to diffract incoming radiation only into certain orders of diffraction, with vanishing diffraction into orders beyond a certain value (section Diffractive Micro-optics, second paragraph). Note that choosing to direct optical power into zeroth and first orders of diffraction would most closely resemble the operation of the Rochon prism in FIG. 3 of Huang, with one beam, the zeroth order, proceeding through the diffractive optical element, and the other beam, the first order beam, diverging from the first order beam.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte and Paschotta, to direct the energy into a zeroth order of diffraction and, in terms of absolute value, first order of diffraction to most closely match the geometry of Huang when using the Rochon prism shown in FIG. 3 of Huang, with predictable results and a reasonable expectation of success.
Regarding claim 9, Huang, as modified by Schulte, teaches the apparatus of claim 7 (as described above).
Huang does not explicitly teach that the beam direction splitter and/or the direction matcher are respectively configured to diffract incoming radiation only into +1st and -1st orders of diffraction.
In the same field of endeavor of manipulating beams of light, Paschotta does teach that the beam direction splitter and/or the direction matcher is respectively configured to diffract incoming radiation only into certain orders of diffraction, with vanishing diffraction into orders beyond a certain value (section Diffractive Micro-optics, second paragraph). Note that choosing to direct optical power into +1st and -1st orders of diffraction would most closely resemble the operation of the Wollaston prism shown in FIG. 4 of Huang, with one beam (such as a +1 order beam) diverging in one direction, while the other beam (such as a -1 order beam) diverges in a different direction.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte and Paschotta, to direct the energy into +1st and -1st orders of diffraction to most closely match the geometry of Huang when using the Wollaston prism shown in FIG. 4 of Huang, with predictable results and a reasonable expectation of success.
Regarding claim 10, Huang, as modified by Schulte, teaches the apparatus of claim 6 (as described above).
Huang does not explicitly teach that the beam direction splitter and the direction matcher are diffractive optical elements with an inverted configuration to one another.
In the same field of endeavor of manipulating beams of light, Paschotta does teach that the beam direction splitter and the direction matcher are diffractive optical elements with an inverted configuration to one another (section Diffractive Micro-optics, paragraph 2, mentions that diffractive optical elements can be used to both split beams and combine them. Note that inputting beams that are offset angularly into the diffractive beam combiner (as shown in FIG. 2B of Huang) can produce output beams that are offset spatially in the manner of beamlets 105a and 105b of Huang). By using diffractive optical elements to split and combine beams, Paschotta offers an alternative manner of producing offset beamlets.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the apparatus of Huang, as modified by Schulte, with the diffractive optical elements of Paschotta as an alternative manner of producing offset beamlets, with predictable results and a reasonable expectation of success.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to PAUL D SCHNASE whose telephone number is (703)756-1691. The examiner can normally be reached Monday - Friday 8:30 AM - 5:00 PM ET.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Tarifur Chowdhury can be reached at (571) 272-2287. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/PAUL SCHNASE/Examiner, Art Unit 2877
/TARIFUR R CHOWDHURY/Supervisory Patent Examiner, Art Unit 2877