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 .
Election/Restrictions
Applicant's election with traverse of Invention II, claims 14-20, in the reply filed on 23 October 2025, is acknowledged. The traversal is on the ground(s) that the method and epitaxial structure claimed in the present application are only related to a SiC substrate with an off-angle greater than zero degree and the method can only use a growth face having an off-angle greater than zero degree. This is not found persuasive because the claim does not recite the angle must be non-zero, and the instant disclosure defines the off-angle as an angle between the growth face and a <0001> axial direction of a silicon carbide (0001) face and does not differ between positivity and negativity (paragraph 0018 of the instant specification) but does not require this angle to be non-zero. Furthermore, Applicant argues that the problem outlined in paragraph 0003 would not occur if the off-angle were to be zero degree, but this is insufficient reason why the method of depositing the claimed sequence of layer can only use a growth face having an off-angle greater than zero degree.
The requirement is still deemed proper and is therefore made FINAL.
Claims 1-13 are withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to a nonelected invention, there being no allowable generic or linking claim. Applicant timely traversed the restriction (election) requirement in the reply filed on 23 October 2025.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
Claims 14-20 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
Claim 14 recites “a nitride angle adjustment layer…deposited to form on the growth face of the nitride angle adjustment layer” in lines 5-6. It is not clear how a layer is to be deposited on itself. In view of the limitation of “a nitride angle adjustment layer located on the growth face of the SiC substrate” (line 5 of claim 14), the disputed limitation will be considered to be deposited to form on the growth face of the SiC substrate.
Claim 19 recites a root mean square but does not recite what set of values the root mean square is for (i.e. RMS is mathematically similar to standard deviation). In the interest of advancing prosecution, the disputed limitation will be considered to refer to RMS roughness, as supported by paragraph 0021 of the instant specification.
Claims 15-18 and 20 are rejected as they depend on a rejected claim.
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP § 2146 et seq. for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
Claims 14, 18, and 19 are provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claims 10-14 of copending Application No. 18/104,605 (reference application). Although the claims at issue are not identical, they are not patentably distinct from each other because they contain the following overlapping subject matter:
Instant claim 14 and claim 10 of the ‘605 application both recite an epitaxial structure comprising a silicon carbide (SiC) substrate, wherein a silicon face (Si-face) of the SiC substrate is taken as a growth face, and the growth face has an off-angle greater than zero degree relative to the Si-face of the SiC substrate; a nitride angle adjustment layer located on the growth face of the SiC substrate, deposited to form on the growth face through physical vapor deposition (PVD); a first group III nitride layer located on the nitride angle adjustment layer; and a second group III nitride layer located on the first group III nitride layer.
Instant claim 14 recites the nitride angle adjustment layer is deposited to form on the growth face of the nitride angle adjustment layer whereas claim 10 of the ‘605 application recites the nitride angle adjustment layer is deposited to form on the growth face of the SiC substrate. However, in view of the nitride angle adjustment layer being located on the growth face of the SiC substrate, and due to the indefiniteness outlined above, instant claim 14 is considered to have the nitride angle adjustment layer deposited to form on the growth face of the SiC substrate.
Instant claim 14 recites the nitride angle adjustment layer having a thickness less than 50 nm, whereas claim 10 of the ‘605 application recites a thickness of the nitride angle adjustment layer is between 5 nm and 50 nm. These ranges overlap, and the courts have held that a prima facie case of obviousness exists where claimed ranges overlap, lie inside of, or are very close to other ranges. See MPEP § 2144.05. It is noted that as of the writing of this Office Action, no demonstration of a criticality to the claimed ranges has been presented.
While not reciting an exact duplicate of claim 10 of the ‘605 application, it would have been obvious to one of ordinary skill in the art before the effective filing date as an obvious variation of the ‘605 application due to the substantial overlap of subject matter.
Instant claim 18 and claim 12 of the ‘605 application both recite the first group III nitride layer is deposited on the nitride angle adjustment layer through metal-organic chemical vapor deposition (MOCVD).
Instant claim 18 and claim 13 of the ‘605 application both recite the first group III nitride is aluminum nitride (AlN) or aluminum-gallium nitride (AlxGa1-xN).
Instant claim 18 and claim 11 of the ‘605 application both recite the nitride angle adjustment layer is aluminum nitride (AlN) or aluminum-gallium nitride (AlxGa1-xN).
Instant claim 18 and claim 14 of the ‘605 application both recite the second group III nitride layer is gallium nitride (GaN).
Instant claim 19 and claim 14 of the ‘605 application both recite the second group III nitride layer is gallium nitride (GaN) and has a root mean square (RMS) roughness less than 1.5 nm.
This is a provisional nonstatutory double patenting rejection because the patentably indistinct claims have not in fact been patented.
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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 14-20 are rejected under 35 U.S.C. 103 as being unpatentable over Narita et al. (JP 2013211442A, machine translation attached) in view of Ota et al. (US 2016/0268381).
Claim 14: Narita teaches a nitride semiconductor epitaxial wafer (i.e. an epitaxial structure) formed with a silicon carbide (SiC) substrate (paragraph 0001). The SiC substrate is an on-axis in the <0001> direction and a Si surface is used (i.e. a silicon face of the SiC substrate is taken as a growth face) (paragraph 0044). An AlN buffer layer is formed on the substrate made of silicon carbide, and a nitride semiconductor crystal is formed on the buffer layer (paragraph 0015). Before forming the AlN buffer layer, a metal layer made of an Al film (from a metal source material containing Al such as TMA; paragraph 0029) is formed on the SiC substrate and then heat treatment is performed in an atmosphere containing ammonia so that the lattice constant of the AlN buffer layer can be controlled (paragraph 0026), such that a layer of fine crystal nuclei of AlN (i.e. a nitride angle adjustment layer located on the growth face of the SiC substrate, see indefiniteness outlined above) is formed (paragraph 0029) and there is no bias in the distribution of Al when crystallized because the Al atoms are likely to move around and form an in-plane uniform layer of Al (paragraph 0032). The average particle diameter of the fine crystal nucleus is set to 8 nm or more and 13.5 nm or less (paragraph 0039) (i.e. a minimum layer thickness of the fine crystal nucleus is the average particle diameter because the layer thickness is not less than one layer of fine crystal nucleus particles), which overlaps the instantly claimed thickness. The courts have held that a prima facie case of obviousness exists where claimed ranges overlap, lie inside of, or are close to ranges in the prior art. See MPEP § 2144.05. It is noted that as of the writing of this Office Action, no demonstration of a criticality to the claimed ranges has been presented. After forming the fine crystal nuclei (i.e. the nitride angle adjustment layer), TMA (i.e. aluminum source) and NH3 (i.e. ammonia) were simultaneously supplied to grow an AlN buffer layer (i.e. a first group III nitride layer located on the nitride angle adjustment layer) (paragraph 0029). A GaN layer (i.e. a second group III nitride layer) is grown on the AlN buffer layer (i.e. on the first group III nitride layer) (paragraphs 0036 and 0050). However, Narita does not teach the instantly claimed off-angle.
In a related field of endeavor, Ota teaches a semiconductor substrate of SiC including a surface inclined from a {0001} face (also including a (0001) face; paragraph 0016) at an off angle of 0° to 10° (paragraph 0013). This off angle overlaps the instantly claimed range. See MPEP § 2144.05. The (0001) face, also indicated as the silicon face, is shown as the growth face (Figs. 1-2). This semiconductor substrate has low area density of the TED clusters and it is possible to suppress the variation of the forward ON voltage and provides high reliability (paragraph 0038).
As Narita and Ota both teach a semiconductor device using a SiC substrate with the silicon face as the growth face, they are analogous. It would have been obvious to one of ordinary skill in the art before the effective filing date to modify the nitride semiconductor epitaxial wafer of Narita to include where the SiC substrate at an off angle of 0° to 10° from the (0001) face as taught by Ota as such substrate can provide high reliability, and one would have had a reasonable expectation of success. Narita does not particularly teach the layer of fine crystal nuclei to be formed by PVD, but this limitation is considered to be a product-by-process limitation which is not limited to the manipulations of the recited steps. See MPEP § 2113.
Claim 15: Ota teaches the off angle is 0° to 10°, which overlaps the instantly claimed range. See MPEP § 2144.05. Narita teaches a layer of fine crystal nuclei of AlN (i.e. a nitride angle adjustment layer located on the growth face of the SiC substrate) is formed (paragraph 0029) and that there is no bias in the distribution of Al when crystallized because the Al atoms are likely to move around and form an in-plane uniform layer of Al (paragraph 0032) and that the layer (i.e. of fine crystal nuclei) changes the lattice constant of the AlN buffer layer (paragraph 0026) to avoid being distorted which affects generation of surface pits (paragraph 0024). This disclosure by Narita compares to the instant disclosure of a nitride angle adjustment layer made of AlN that automatically performs an angle adjustment process and therefore improves epitaxial quality of the first group III nitride layer and the second group II nitride layer (paragraph 0028 of the instant specification). As such, the instantly claimed FWHM is considered to be present because substantially identical materials have substantially identical properties. See MPEP § 2112.01.
Claim 16: Ota teaches the off angle is 0° to 10°, which overlaps the instantly claimed range. See MPEP § 2144.05. Narita teaches a layer of fine crystal nuclei of AlN (i.e. a nitride angle adjustment layer located on the growth face of the SiC substrate) is formed (paragraph 0029), and the average particle diameter of the fine crystal nucleus is set to 8 nm or more and 13.5 nm or less (paragraph 0039) (i.e. a minimum layer thickness of the fine crystal nucleus is the average particle diameter because the layer thickness is not less than one layer of fine crystal nucleus particles), which overlaps the instantly claimed thickness. See MPEP § 2144.05. The instantly claimed FWHM is considered to be present for the same reasons outlined above regarding FWHM of instant claim 15.
Claim 17: Ota teaches the off angle is 0° to 10°, which overlaps the instantly claimed range. See MPEP § 2144.05. Narita teaches a layer of fine crystal nuclei of AlN (i.e. a nitride angle adjustment layer located on the growth face of the SiC substrate) is formed (paragraph 0029), and the average particle diameter of the fine crystal nucleus is set to 8 nm or more and 13.5 nm or less (paragraph 0039) (i.e. a minimum layer thickness of the fine crystal nucleus is the average particle diameter because the layer thickness is not less than one layer of fine crystal nucleus particles), which overlaps the instantly claimed thickness. See MPEP § 2144.05. The instantly claimed FWHM is considered to be present for the same reasons outlined above regarding FWHM of instant claim 15.
Claim 18: Narita teaches that after forming the fine crystal nuclei of AlN (i.e. the nitride angle adjustment layer), TMA (i.e. aluminum source) and NH3 (i.e. ammonia) were simultaneously supplied to grow an AlN buffer layer (i.e. the first group III nitride layer located on the nitride angle adjustment layer) (paragraph 0029). A GaN layer (i.e. the second group III nitride layer) is grown on the AlN buffer layer (i.e. on the first group III nitride layer) (paragraphs 0036 and 0050). These layers can be formed by metal organic chemical vapor deposition (paragraphs 0005 and 0059).
Claims 19-20: Narita teaches a GaN layer (i.e. the second group III nitride layer) is grown on the AlN buffer layer (i.e. on the first group III nitride layer) (paragraphs 0036 and 0050). Narita does not specifically teach a root mean square roughness (see indefiniteness outlined above) or FWHM, but does teach that the nitride semiconductor epitaxial wafer (i.e. including the GaN layer) is manufactured by the MOVPE (i.e. metal organic chemical vapor deposition; paragraph 0005) apparatus (i.e. by epitaxial growth) (paragraph 0059) and no pits were observed (paragraphs 0051, 0053, and 0055), presumably due to lack of lattice distortion of the AlN buffer layer (paragraph 0024) and in-plane uniform layer of Al that forms the fine crystal nuclei (paragraph 0032). These teachings support a conclusion of the GaN layer being substantially defect-free and substantially uniform. Furthermore, the GaN layer is considered to have a substantially identical RMS roughness and FWHM because substantially identical materials have substantially identical properties. See MPEP § 2112.01.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Chuang et al. (US 12,112,985) claims a semiconductor substrate of a silicon carbide having an angle of 0° to +/-8° with respect to a (0001) plane, a buffer layer, and a gallium nitride epitaxial layer having a FWHM of the (002) plane of less than 100 arcsec (claims 1, 4).
Omori et al. (US 2016/0293710) teaches a nitride semiconductor having a single crystal substrate such as SiC, a first layer of AlN formed on the substrate, and a layered structure of a second layer of AlxGa1-xN, a third layer and fourth layer of alternating layers of AlN and GaN.
Ohta et al. (US 2012/0049156) teaches a nitride semiconductor device where the growth surface includes a plane having an off angle in the c axis direction (i.e. the (0001) face) being 0.1-10 degrees to improve crystal quality and improving the flatness (paragraph 0023).
Kikkawa et al. (US 7,875,535) teaches a compound semiconductor device of a SiC substrate, an AlN buffer layer containing Cl, an AlN layer not containing Cl, and device constituent layer(s) which includes a GaN layer. The AlN layer containing Cl can be formed by hydride vapor phase epitaxy.
Lin et al. (US 2009/0256159) teaches a GaN semiconductor device where the substrate may be SiC. A metal-rich nitride thin film is formed, followed by a buffer layer of GaN or AlN, and then a semiconductor layer.
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/KIM S. HORGER/Examiner, Art Unit 1784