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 amendment of 7/9/2026.
Response to Arguments
Preliminary Matters
Regarding the priority of Paschotta, the previously provided copy contains a complete URL at the bottom of each page which directs to an archive of the page as it existed on 5/19/2022, more than a year before the effective filing date of the claimed invention. The URL for the most recent version of the page is also recited several times in the provided copy but is not relied on, as it may have been updated since the effective filing date.
Prior Art Rejections
Applicant’s first argument is that Huang only teaches measuring flatness rather than an aspherical or free-form surface; however, this argument is unpersuasive. Huang is relied on to teach a shearing interferometer that uses two transversely offset beams at normal incidence on a surface under test to measure the shape of that surface. Schulte is relied on for the wavefront adapter needed to apply the concept of shearing interferometry to an aspherical or free-form surface. Note the embodiment of Huang relied on in this and the previous action, shown in FIG. 2B, does not include reference flat 114, so the flatness of a reference flat is likewise moot.
Applicant’s second argument is that Shulte does not teach adapting the reference wave to the shape of the object under test; however, this argument is unpersuasive. Huang, not Schulte, is relied on to teach the practice of sending both beams to the object under test with an offset. It may be noted that sending two parallel plane waves into the diffractive structure pattern 64 of Schulte would predictably result in both plane waves being adapted to the aspherical or free-form shape of test object 14.
In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
Similar arguments regarding independent claim 18 are similarly unpersuasive.
As the independent claims are not allowed, the dependent claims are not automatically allowable.
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 11-20 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).
Huang does not explicitly teach the test surface configured as an aspherical or free-form surface, and 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 an aspherical or free-form 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 the test surface configured as an aspherical or free-form surface (paragraph 61 describes the optical test object as a free-form surface) and 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 an aspherical or free-form 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 the predictable result of adapting both parallel wavefronts to the aspherical or free-form target surface 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 object under test comprises 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).
Huang does not explicitly teach that the test surface is configured as an aspherical or free-form surface, and 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 that the test surface is configured as an aspherical or free-form surface (paragraph 61 describes the optical test object as a free-form surface), and 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 the predictable result of adapting both parallel wavefronts to the aspherical or free-form target surface and a reasonable expectation of success.
Regarding claim 19, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches an environment in which the two plane waves with parallel directions of propagation propagate (All wave propagation inherently occurs in an environment).
While Huang appears to be silent as to the pressure of the environment in which the apparatus operates, so does not explicitly state that the environment comprises an environment at ambient pressure, coarse vacuum or fine vacuum, it may be noted that a) the overlap between the optical paths for the two interfering beams (as seen in FIG. 2B) would provide resistance to distortion due to air or other gases in the common beam path and b) placing the device in an environment other than ambient pressure, course vacuum, or fine vacuum would require considerable effort, effort of which there is no evidence (environments tend toward ambient pressure). Absent evidence to the contrary, it is the Examiner’s position that Huang used an environment at ambient pressure, course vacuum, or fine vacuum, rather than using, but not disclosing, an environment with high (or higher) vacuum.
Alternatively if Huang did use a high vacuum without disclosing that use, 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 using either a lower vacuum or no vacuum at all, taking advantage of the distortion resistance due to the largely shared beam path between the two interfering beams, with predictable results and a reasonable expectation of success.
Regarding claim 20, Huang, as modified by Schulte, teaches the apparatus of claim 1 (as described above).
Huang further teaches that the object under test comprises an optical element for microlithography (paragraph 7, the apparatus measures light reflected from the sample, which indicates that it is compatible with use measuring a mirror, a type of optical element. A mirror may be used for microlithography. 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.).
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
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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
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