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 without traverse of Group I, claims 1-18, in the reply filed on 21 November 2025 is acknowledged.
The requirement is still deemed proper and is therefore made FINAL.
Claims 19-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 21 November 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 1-18 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.
Claims 1 and 9 each recite a resistivity of at least 100 kΩ. However, the instant specification discloses measuring both sheet resistivity and bulk resistivity (paragraph 00108) having units of ohm/sq and ohm.cm, respectively (Table 1B). Furthermore, the values of these two types of resistivity are not identical for a given material, as evidenced by the values disclosed in Table 1B of the instant specification. The type of resistivity being claimed is not clear due to the difference in units and in view of the values being different depending on the type of resistivity being measured.
Claims 5 and 15 each recite a resistivity of at least 1 MΩ, and are unclear for the same reasons outlined regarding claim 1.
Claims 9 and 13-14 each recite a sub-layer of “non-extrinsically carbon-doped gallium nitride”. It is not clear if the material is a carbon-doped gallium nitride that is doped non-extrinsically or is a gallium nitride that is not extrinsically carbon-doped (i.e. not doped with carbon). The instant specification provides verbatim support for the limitation (paragraph 0005 of the instant specification) but not any further explanation. For the purposes of searching for and applying prior art, either interpretation will be considered as meeting this limitation.
Claim 18 recites the limitation “wherein the layer of extrinsically carbon-doped N-polar gallium nitride” in line 2. There is insufficient antecedent basis for this limitation because the base claim and intervening dependent claim do not recite the gallium nitride as being N-polar. It is suggested that instant claim 18 should depend upon instant claim 11.
Claims 2-4, and 6-8, 10-14, and 16-17 are rejected as they depend on a rejected claim.
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.
Claims 1-18 are rejected under 35 U.S.C. 103 as being unpatentable over Okahisa et al. (US 8,421,190) in view of Mohanty et al. (Progress in Quantum Electronics 2023, NPL attached).
Claim 1: Okahisa teaches a group III nitride semiconductor substrate having controlled resistivity and low dislocation density (Col. 2, l. 9-12). The group III nitride preferably is a GaN substrate (i.e. a gallium nitride containing structure) (Col. 4, l. 56-60) and contains at least one impurity element (i.e. dopant) selected from C, Fe, etc. in a concentration not lower than 1x1017 cm-3 (Col. 4, l. 13-25) (i.e. a carbon-doped gallium nitride would have been obvious). This concentration of carbon dopant overlaps the instantly claimed range and 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. By adding at least one element from among C, etc. by at least 1x1017 cm-3 to the group III nitride semiconductor will attain a carrier density (i.e. electron concentration) not higher than 1x1015 cm-3 and the resistivity can readily be controlled to at least 1x104 Ω∙cm (Col. 3, l. 18-26). This resistivity is considered to be a bulk resistivity based on the units of Ω∙cm, and Okahisa teaches a thickness of at least 70 µm (Col. 2, l. 13-23). The resistivity through the thickness then is about 1.4x106 Ω (i.e. estimated as the bulk resistivity of at least 1x104 Ω∙cm divided by the thickness of at least 70 µm), or about 1400 kΩ, which overlaps the instantly claimed range. See MPEP § 2144.05. Furthermore, this resistivity overlapping the instantly claimed resistivity is considered to teach the gallium nitride semiconductor to be semi-insulating. The group III nitride semiconductor can be epitaxially grown by various vapor deposition methods such as HVPE, MOCVD, and MBE (Col. 6, l. 53-63). The limitation of being extrinsically carbon-doped is acknowledged, but is considered a product-by-process limitation and therefore is not limited to the manipulations of the recited steps, only the structure implied by the steps. See MPEP § 2113. As outlined above, Okahisa teaches substantially identical carbon dopant concentration, carrier density (i.e. electron concentration), and resistivity as the instantly claimed gallium nitride-containing structure. However, Okahisa does not teach the gallium nitride semiconductor to be N-polar.
In a related field of endeavor, Mohanty teaches that surface termination III-nitrides can have either a group III element polarity or a N-polarity, with distinctive features of N-polar GaN-based devices over conventional Ga-polar structures for high-power high-frequency amplifying applications being improved output resistance and pinch-off of the devices, ohmic contact formed on the smaller-bandgap channel material to enable lower contact resistivity, and better gate control (Introduction). Mohanty teaches that N-polar nitrides can be formed by epitaxial growth via MOCVD, plasma-assisted MBE, etc. (Introduction).
As Okahisa and Mohanty both teach group III nitrides, more specifically GaN-based, that can be formed by epitaxial growth via MOCVD, MBE, etc., they are analogous. It would have been obvious to one of ordinary skill in the art before the effective filing date to modify the GaN doped with carbon of Okahisa to include where the GaN-based group III nitride is N-polar as taught by Mohanty because the N-polar GaN-based devices have distinctive features over conventional Ga-polar devices, and one would have had a reasonable expectation of success.
Claim 2: Okahisa teaches that the concentration distribution of the impurity (i.e. dopant, such as C) as a ratio of a maximum concentration to a minimum concentration is 1 to 3 (i.e. a fairly uniform distribution) (Col. 2, l. 13-23). Okahisa further teaches that the group III nitride semiconductor is desirably grown, using as the growth surface, a uniform surface where there is no difference in the amount of incorporation of the impurity element (i.e. the dopant), and in other words the group III nitride semiconductor layer is preferably grown while the average growth surface of the group III nitride semiconductor layer maintains a flat uniform surface which can be grown while adding at least one impurity element (i.e. dopant) such as C by at least 1x1017 cm-3 during epitaxial growth (Col. 7, l. 61 to Col. 8, l. 14). This is considered to teach the dopant concentration being maintained through the entire thickness.
Claim 3: Okahisa teaches maintaining a flat uniform surface (Col. 7, l. 61 to Col. 8, l. 14) but does not teach a quantitative surface roughness. Mohanty teaches the miscut angle of the substrate affect the formation of hexagonal hillocks and shows in Fig. 11 samples grown in Ga-rich regime and nitrogen-rich regimes with different miscut angles. Five of the eight samples had RMS values less than 1.0 nm for a 2x2 µm2 area measured by AFM (Figure 11, figure caption). These five samples have an RMS surface roughness that overlaps the instantly claimed range.
Claim 4: Okahisa teaches that the substrate may be a sapphire substrate (Col. 3, l. 28-37). Mohanty also teaches the substrate may be sapphire (section 2 on p. 2).
Claim 5: Okahisa teaches the resistivity can readily be controlled to at least 1x104 Ω∙cm (Col. 3, l. 18-26). This resistivity is considered to be a bulk resistivity based on the units of Ω∙cm, and Okahisa teaches a thickness of at least 70 µm (Col. 2, l. 13-23). The resistivity through the thickness then is about 1.4x106 Ω (i.e. estimated as the bulk resistivity of at least 1x104 Ω∙cm divided by the thickness of at least 70 µm), or about 1.4 MΩ, which overlaps the instantly claimed range. See MPEP § 2144.05.
Claims 6 and 8: Okahisa teaches adding at least one element from among C, etc. by at least 1x1017 cm-3 to the group III nitride semiconductor (Col. 3, l. 18-26) and a specific example where the content of impurity element C (i.e. carbon dopant) was 1018 cm-3 (Col. 11, l. 27-31). These ranges overlap the instantly claimed range. See MPEP § 2144.05.
Claim 7: Okahisa teaches a carrier density (i.e. electron concentration) not higher than 1x1015 cm-3 (Col. 3, l. 18-26), which overlaps the instantly claimed range. See MPEP § 2144.05.
Claim 9: The limitations of claim 9 include the limitations recited in instant claim 1 (outlined above) where the semi-insulating, extrinsically carbon-doped gallium nitride-containing structure outline instant claim 1 is an overlayer on a sublayer of non-extrinsically carbon-doped gallium nitride having a thickness of greater than 10 nm on a surface of the substrate. In this regard, Okahisa teaches a group III nitride semiconductor including a first group III nitride form with at least one element selected from C, etc. added as an impurity (i.e. dopant) by at least 1x1017 cm-3 to the first group II nitride semiconductor layer (i.e. a sublayer), a second group III nitride semiconductor layer, and a third group III nitride semiconductor layer on the first or second group III nitride semiconductor layer wherein the third group III nitride semiconductor layer includes at least one element selected from C, etc. added as an impurity element (i.e. a dopant) by at least 1x1017 cm-3 to the third group III nitride semiconductor layer (Col. 2, line 50 to Col. 3, line 15). Okahisa teaches the thickness of such layers to be at least 70 µm (Col. 2, lines 13-34). The limitations of being extrinsically doped (for the overlayer) and non-extrinsically doped (for the sublayer) is acknowledged but are considered to be product-by-process limitations (i.e. how to cause the doping) and therefore is not limited to the manipulations of the recited steps, only the structure implied by the steps. See MPEP § 2113.
Claim 10: Okahisa teaches that the substrate may be a sapphire substrate (Col. 3, l. 28-37). Mohanty also teaches the substrate may be sapphire (section 2 on p. 2).
Claim 11: The limitation of the gallium nitride being N-polar gallium nitride is addressed above regarding claim 1 as being obvious in view of Mohanty.
Claim 12: Mohanty teaches that surface termination III-nitrides can have either a group III element polarity or a N-polarity, with Ga-polar structures being predominantly fabricated due to easier epitaxial growth (Introduction). It would have been obvious to one of ordinary skill in the art before the effective filing date to modify the gallium nitride structure of Okahisa to be Ga-polar as taught by Mohanty as this is considered a conventionally known gallium nitride polarity that provides easier epitaxial growth.
Claims 13-14: Okahisa teaches the thickness of the layers (i.e. the sublayer) to be at least 70 µm (Col. 2, lines 13-34), which overlaps the instantly claimed ranges. See MPEP § 2144.05.
Claim 15: Okahisa teaches the resistivity can readily be controlled to at least 1x104 Ω∙cm (Col. 3, l. 18-26). This resistivity is considered to be a bulk resistivity based on the units of Ω∙cm, and Okahisa teaches a thickness of at least 70 µm (Col. 2, l. 13-23). The resistivity through the thickness then is about 1.4x106 Ω (i.e. estimated as the bulk resistivity of at least 1x104 Ω∙cm divided by the thickness of at least 70 µm), or about 1.4 MΩ, which overlaps the instantly claimed range. See MPEP § 2144.05.
Claims 16 and 18: Okahisa teaches adding at least one element from among C, etc. by at least 1x1017 cm-3 to the group III nitride semiconductor (Col. 3, l. 18-26) and a specific example where the content of impurity element C (i.e. carbon dopant) was 1018 cm-3 (Col. 11, l. 27-31). These ranges overlap the instantly claimed ranges. See MPEP § 2144.05.
Claim 17: Okahisa teaches a carrier density (i.e. electron concentration) not higher than 1x1015 cm-3 (Col. 3, l. 18-26), which overlaps the instantly claimed range. See MPEP § 2144.05.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Keller et al. (US 2016/0133737) teaches a semiconductor device having a group III-N semiconductor layer, such as GaN, with carbon doping levels of between 1x1017 and 1x1019 cm-3 and the resistivity level can be greater than 1x107 ohm-cm for carbon doping levels of about 1x1019 cm-3.
Kucharski et al. (US 2017/0253990) teaches a gallium containing nitride that contains acceptors selected from carbon, etc. with a total concentration of not more than 1x1021 cm-3, preferably not more than 1x1020 cm-3, further contains oxygen and being a semi-insulating material with a resistivity higher than 1x106 Ωcm, preferably higher than 1x1010 Ωcm.
Suzuki et al. (US 2022/0069090) teaches a carbon-doped GaN layer having a thickness of 550-3000 nm and an average carbon concentration of 3x1018/cm3 to 5x1020/cm3.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to KIM S HORGER whose telephone number is (571)270-5904. The examiner can normally be reached M-F 9:30 AM - 4:00 PM EST.
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/KIM S. HORGER/Examiner, Art Unit 1784