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 without traverse of claims 1-7 in the reply filed on May 20, 2026 is acknowledged. Claims 8-19 are withdrawn from further consideration.
Information Disclosure Statement
The information disclosure statements (IDS)s submitted on February 22, 2024 and August 25, 2025 were filed before the mailing of a first Office action on the merits. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statements are being considered by the examiner.
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 2-4 and 7 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 2 recites the limitation “wherein the gallium nitride layer is about 800 nm,” on page 2 lines 10-11. The term “about” in claim 2 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The term “about” renders claim 2 indefinite because the thickness of the gallium nitride layer is unclear. For examination purposes, claim 2 will be interpreted as reciting wherein the gallium nitride layer is 800 nm.
Claim 3 recites the limitation “the sub-barrier layer being aluminum nitride having a thickness of about 1 nm,” on page 2 lines 14-15. The term “about” in claim 3 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The term “about” renders claim 3 indefinite because the thickness of the aluminum nitride layer is unclear. For examination purposes, claim 3 will be interpreted as the sub-barrier layer being aluminum nitride having a thickness of between 1 nm – 5 nm. The examiner notes that the range of between 1 nm – 5 nm is recited in paragraph 48 of the specification.
Claim 4 is also rejected for containing the same limitation because claim 4 depends from claim 3.
Claim 3 recites the limitation “the main barrier layer being aluminum gallium nitride having a thickness of about 18 nm,” on page 2 lines 15-16. The term “about” in claim 3 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The term “about” renders claim 3 indefinite because the thickness of the aluminum gallium nitride layer is unclear. For examination purposes, claim 3 will be interpreted as the main barrier layer being aluminum gallium nitride having a thickness of between 5 nm – 30 nm. The examiner notes that the range of between 5 nm – 30 nm is recited in paragraph 49 of the specification.
Claim 4 is also rejected for containing the same limitation because claim 4 depends from claim 3.
Claim 4 recites the limitation “the cap layer being gallium nitride having a thickness of about 2 nm,” on page 2 line 19. The term “about” in claim 4 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The term “about” renders claim 4 indefinite because the thickness of the gallium nitride layer is unclear. For examination purposes, claim 4 will be interpreted as the cap layer being gallium nitride having a thickness of between 1 nm – 4 nm. The examiner notes that the range of between 1 nm – 4 nm is recited in paragraph 49 of the specification.
Claim 7 recites the limitation “wherein the first gallium nitride layer is intentionally doped with carbon to a concentration of about 1x1018 to 5x1018 cm-3,” on page 2 line 28 and page 3 line 1. The term “about” in claim 7 is a relative term which renders the claim indefinite. The term “about” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. The term “about” renders claim 7 indefinite because the thickness of the carbon doping concentration of the first gallium nitride layer is unclear. For examination purposes, claim 7 will be interpreted as wherein the first gallium nitride layer is intentionally doped with carbon to a concentration of 1x1018 to 5x1018 cm-3.
Claim Rejections - 35 USC § 102
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.
Claims 1 and 3-6 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Durmus et al. (“AlGaN/GaN HEMT with fT: 100GHZ and fmax: 128GHz”).
Regarding Claim 1:
Durmus discloses an epiwafer comprising:
a substrate (4H-SiC Substrate, See fig. 1, ref. no. SiC, Section II paragraph 1) that includes at least a silicon carbide layer;
a nucleation layer (AlN nucleation layer, See fig. 1, ref. no. AlN and Section II paragraph 2) over the silicon carbide layer;
a gallium nitride layer (undoped GaN buffer layer, See fig. 1, ref. no. GaN and Section II paragraph 2) over the nucleation layer, having a thickness of greater than 600 nm (the undoped GaN buffer layer has a thickness of 2 µm, See fig. 1, ref. no. GaN and Section II paragraph 2) and a concentration of iron that is less than or equal to 1x1016 cm-3 (undoped GaN buffer layer, See Section II paragraph 2. The examiner notes that the gallium nitride layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the gallium nitride layer includes gallium and nitrogen and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the undoped GaN buffer layer has a concentration of iron that is less than or equal to 1x1016 cm-3.); and
a barrier layer (1.5nm AlN interlayer and 20nm undoped AlGaN layer, See fig. 1, ref. nos. AlN and AlGaN and Section II paragraph 2) over the gallium nitride layer.
Regarding Claim 3:
Durmus discloses wherein the barrier layer is comprised of a sub-barrier layer (1.5nm AlN interlayer, See fig. 1, ref. no. AlN and Section II paragraph 2) and a barrier layer (20 nm undoped AlGaN layer, See fig. 1, ref. no. AlGaN and Section II paragraph 2), the sub-barrier layer being aluminum nitride having a thickness of about 1 nm (1.5nm AlN interlayer, See fig. 1, ref. nos. AlN and Section II paragraph 2) and the main barrier layer being aluminum gallium nitride having a thickness of about 18 nm (20 nm undoped AlGaN layer, See fig. 1, ref. no. AlGaN and Section II paragraph 2).
Regarding Claim 4:
Durmus discloses a cap layer (2nm GaN cap layer, See fig. 1, ref. no. GaN and Section II paragraph 2) over the barrier layer, the cap layer being gallium nitride having a thickness of about 2 nm (2nm GaN cap layer, See fig. 1, ref. no. GaN and Section II paragraph 2).
Regarding Claim 5:
Durmus discloses wherein the silicon carbide layer is a 4H silicon carbide layer (4H-SiC Substrate, See fig. 1, ref. no. SiC, Section II paragraph 1).
Regarding Claim 6:
Durmus discloses wherein the gallium nitride layer has a concentration of carbon less than 3x1016cm-3 (undoped GaN buffer layer, See Section II paragraph 2. The examiner notes that the gallium nitride layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the gallium nitride layer includes gallium and nitrogen and does not include a concentration of carbon greater than or equal to 3x1016 cm-3. Thus, the undoped GaN buffer layer has a concentration of carbon less than 3x1016 cm-3.)
Claims 1-2 and 6 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Chiu et al. (“Microwave Wide Bandgap GaN High Electron Mobility Transistor Development and its Monolithic Integrated Circuits (Invited)”).
Regarding Claim 1:
Chiu discloses an epiwafer comprising:
a substrate (4 inch SiC substrate, See fig. 1, ref. no. 4” SiC substrate and Section I paragraph 3) that includes at least a silicon carbide layer;
a nucleation layer (100nm AlN layer, See fig. 1, ref. no. AlN) over the silicon carbide layer;
a gallium nitride layer (undoped GaN channel layer, See fig. 1, ref. no. GaN and Section I paragraph 3) over the nucleation layer, having a thickness of greater than 600 nm (the undoped GaN channel layer has a thickness of 0.8 µm, See fig. 1, ref. no. GaN and Section I paragraph 3) and a concentration of iron that is less than or equal to 1x1016 cm-3 (undoped GaN channel layer, See Section I paragraph 3. The examiner notes that the gallium nitride layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the gallium nitride layer includes gallium and nitrogen and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the undoped GaN channel layer has a concentration of iron that is less than or equal to 1x1016 cm-3.); and
a barrier layer (undoped AlGaN layer, See fig. 1, ref. no. Al0.25GaN and Section I paragraph 3) over the gallium nitride layer.
Regarding Claim 2:
Chiu discloses wherein the gallium nitride layer is about 800 nm (the undoped GaN channel layer has a thickness of 0.8 µm, See fig. 1, ref. no. GaN and Section I paragraph 3).
Regarding Claim 6:
Chiu discloses wherein the gallium nitride layer has a concentration of carbon less than 3x1016cm-3 (undoped GaN channel layer, See Section I paragraph 3. The examiner notes that the gallium nitride layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the gallium nitride layer includes gallium and nitrogen and does not include a concentration of carbon greater than or equal to 3x1016 cm-3. Thus, the undoped GaN channel layer has a concentration of carbon less than 3x1016 cm-3.)
Claims 1 and 7 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Bahat-Treidel et al. (“AlGaN/GaN/GaN:C Back-Barrier HFETs With Breakdown Voltage Over 1 kV and Low RON x A”).
Regarding Claim 1:
Bahat-Treidel discloses an epiwafer comprising:
a substrate (4H-SiC substrate, See fig. 1, ref. no. SiC Substrate, table 1 Wafer B, Section I paragraph 9, Section II subsection A paragraphs 1-2) that includes at least a silicon carbide layer;
a nucleation layer (AlN Nucleation layer, See fig. 1, ref. no. AlN Nucleation layer) over the silicon carbide layer;
a gallium nitride layer (carbon doped GaN back barrier and unintentionally doped GaN channel layer, See fig. 1, ref. no. C-Doped GaN back buffer, GaN Channel, table I Wafer B and Section II, subsection A paragraph 2) over the nucleation layer, having a thickness of greater than 600 nm (the combined thickness of the carbon doped GaN back buffer and unintentionally doped GaN channel layer is 1535 nm, See table I Wafer B) and a concentration of iron that is less than or equal to 1x1016 cm-3 (carbon doped GaN back buffer and unintentionally doped GaN channel layer, See table I Wafer B and Section II, subsection A paragraph 2. The examiner notes that the carbon doped gallium nitride back barrier is formed by the elements gallium and nitrogen and doped with carbon. The examiner next notes that carbon is the sole element used in doping the carbon doped gallium nitride back barrier. Therefore, the gallium nitride back barrier includes gallium, nitrogen, and carbon and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the carbon doped GaN back barrier has a concentration of iron that is less than or equal to 1x1016 cm-3. The examiner notes that the gallium nitride channel layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the gallium nitride channel layer includes gallium and nitrogen and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the unintentionally doped GaN channel layer has a concentration of iron that is less than or equal to 1x1016 cm-3.); and
a barrier layer (AlGaN Barrier layer, See fig. 1, ref. no. AlGaN Barrier and Section II, subsection A paragraph 2) over the gallium nitride layer.
Regarding Claim 7:
Bahat-Treidel discloses wherein the gallium nitride layer is comprised of a first gallium nitride layer (carbon doped GaN back barrier, See fig. 1, ref. no. C-Doped GaN back barrier, table I Wafer B and Section II, subsection A paragraph 2) over the nucleation layer and a second gallium nitride layer (unintentionally doped GaN channel layer, See fig. 1, ref. no. GaN Channel, table I Wafer B and Section II, subsection A paragraph 2) over the first gallium nitride layer, further wherein the first gallium nitride layer is intentionally doped with carbon to a concentration of about 1x1018 to 5x1018 cm-3 (carbon concentration of the C-Doped GaN back barrier is 1x1018 and the second gallium nitride layer is not intentionally doped with carbon (unintentionally doped GaN channel layer, See fig. 1, ref. no., GaN Channel, table I Wafer B and Section II, subsection A paragraph 2).
Claim 1 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by Dharmarasu et al. (“AlGaN/GaN HEMT grown on SiC with carbon doped GaN buffer by MOCVD”).
Regarding Claim 1:
Dharmarasu discloses an epiwafer comprising:
a substrate (4-inch Si-SiC substrate, See fig. 2, ref. no. SiC, Section Experimental Details paragraph 2) that includes at least a silicon carbide layer;
a nucleation layer (AlN layer, See fig. 2, ref. no. AlN) over the silicon carbide layer;
a gallium nitride layer (carbon doped GaN buffer layer and undoped GaN buffer layer, See fig. 2, ref. nos. C-GaN, U-GaN, Section Experimental Details paragraphs 1-2. The examiner notes that the U preceding GaN refers to the layer being undoped.) over the nucleation layer, having a thickness of greater than 600 nm (the combined thickness of the carbon doped GaN buffer layer and undoped GaN buffer layer is 1000 nm, See fig. 2, ref. nos. C-GaN, U-GaN,) and a concentration of iron that is less than or equal to 1x1016 cm-3 (carbon doped GaN buffer layer and undoped GaN buffer layer, See fig. 2, ref. nos. C-GaN, U-GaN, Section Experimental Details paragraphs 1-2. The examiner notes that the carbon doped gallium nitride buffer layer is formed by the elements gallium and nitrogen and doped with carbon. The examiner next notes that carbon is the sole element used in doping the carbon doped gallium nitride buffer layer. Therefore, the gallium nitride buffer layer includes gallium, nitrogen, and carbon and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the carbon doped GaN buffer layer has a concentration of iron that is less than or equal to 1x1016 cm-3. The examiner notes that the undoped gallium nitride buffer layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. Therefore, the undoped gallium nitride buffer layer includes gallium and nitrogen and does not include a concentration of iron greater than 1x1016 cm-3. Thus, the undoped GaN buffer layer has a concentration of iron that is less than or equal to 1x1016 cm-3.)); and
a barrier layer (AlGaN layer, See fig. 2, ref. no. AlGaN) over the gallium nitride layer.
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.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Dharmarasu et al. (“AlGaN/GaN HEMT grown on SiC with carbon doped GaN buffer by MOCVD”).
Regarding Claim 7:
Dharmarasu discloses wherein the gallium nitride layer is comprised of a first gallium nitride layer (carbon doped GaN buffer layer, See fig. 2, ref. no. C-GaN, Section Experimental Details paragraphs 1-2) over the nucleation layer and a second gallium nitride layer (undoped GaN buffer layer, See fig. 2, ref. no. U-GaN, Section Experimental Details paragraphs 1-2) over the first gallium nitride layer and the second gallium nitride layer is not intentionally doped with carbon (The examiner notes that the undoped gallium nitride buffer layer is formed by the elements gallium and nitrogen and that the gallium nitride layer is not doped with other elements. The examiner also notes the Dharmarasu discloses keeping an unintentional concentration of carbon in the undoped gallium nitride buffer layer to a low level, less than 2x1016 cm-3. See Section Experimental Details paragraphs 1-2 ). The examiner notes that Dharmarasu discloses in the third example the carbon doped GaN buffer layer has a carbon concentration of 8x1017 cm-3. See Experimental Details paragraphs 1-2 and Table 1. The examiner also notes the Dharmarasu discloses a carbon doped GaN buffer layer may have a carbon concentration of up to 3x1018 cm-3. See Dharmarasu Section Introduction paragraph 1. The examiner now points out that the carbon concentration of a carbon doped GaN buffer layer is a result effective variable because adjusting the carbon concentration adjusts the resistivity of the carbon doped GaN buffer layer. The examiner additionally points out that the carbon concentration of the a carbon doped GaN buffer layer is recognized by the prior art as a result-effective variable. The examiner notes the Dharmarasu discloses adjusting the carbon concentration of the carbon doped GaN buffer layer adjusts the resistivity of the carbon doped GaN buffer layer. See Dharmarasu Section Introduction paragraph 1 and Table 1. The examiner next notes that optimization of result effective variables through routine experimentation is an obviousness expedient and not a patentable distinction. “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have the first gallium nitride layer intentionally doped with carbon to a concentration of about 1x1018 to 5x1018 cm-3 to reduce buffer leakage current and enhance breakdown voltage. (See Dharmarasu Section Introduction paragraph 1.)
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2002/0167023 to Chavarkar et al. discloses fabricating high electron mobility transistors on silicon carbide substrates because silicon carbide has a much close crystal lattice to Group III nitride than sapphire. See paragraphs 24-25.
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/CALEEN O SULLIVAN/Primary Examiner, Art Unit 2899
/B.S./Examiner, Art Unit 2899
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