DETAILED ACTION
Notice of 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 .
IDS
The IDS document(s) filed on May 28, 2024 and December 26, 2025 and January 12, 2026 have been considered. Copies of the PTO-1449 documents are herewith enclosed with this office action.
Specifications
The title is objected to because a more descriptive title is requested.
Claim Rejections – 35 U.S.C. § 112(b)
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 1-8 are rejected under 35 U.S.C. § 112(b) or pre-AIA 35 U.S.C. § 112, 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 pre-AIA the applicant, regards as the invention.
As to claims 1, 3, and 4, it is unclear which structure is “without being in contact with the anode electrode”. The Examiner assumes the bottom surface of the center trench is not in contact with the anode electrode.
Claim Rejections - 35 U.S.C. § 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 of this title, 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.
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 1-6 are rejected under 35 U.S.C. § 103 as being unpatentable over Hshieh et al. (U.S. Patent Publication No. 2002/0066926 A1), as cited in the IDS and hereafter “Hshieh”, and further in view of Arima et al. (U.S. Patent Publication No. 2021/0119062 A1), hereafter “Arima”.
As to claim 1, Hshieh teaches:
A semiconductor substrate 12c. See Hshieh, FIG. 7.
A drift layer 12d provided on the semiconductor substrate.
An anode electrode 18 brought into Schottky contact with the drift layer.
A cathode electrode (not shown) brought into ohmic contact with the semiconductor substrate. Hshieh teaches but does not depict a cathode electrode. Id. at ¶ [0040].
Wherein the drift layer has a center trench (either of depicted trenches) filled with the anode electrode.
Wherein a bottom surface of the center trench is covered with an insulating film 16 without being in contact with the anode electrode. The Examiner assumes the bottom surface of the center trench, per the 35 U.S.C. § 112(b) rejection interpretation above, is not in contact with the anode electrode.
Wherein at least a part of a side surface of the center trench is brought into Schottky contact with the anode electrode. Id. at ¶ [0039].
However, Hshieh does not teach the semiconductor substrate made of gallium oxide nor the drift layer made of gallium oxide.
On the other hand, Arima teaches s semiconductor substrate 20 formed from gallium oxide and a drift layer 30 formed from gallium oxide. See Arima, FIG. 3, ¶ [0035].
It would have been obvious to one of ordinary skill in the art before the effective filing date to incorporate gallium oxide material for the semiconductor substrate and drift layer as taught by Arima, into the Schottky barrier diode structure having a semiconductor substrate and drift layer as taught by Hshieh, in order to yield the predictable benefit of achieving a Schottky barrier diode structure with a higher withstand voltage. Id. at ¶ [0003].
Furthermore, it would have been obvious to one having ordinary skill in the art before the effective filing date to use gallium oxide, since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 125 USPQ 416.
As to claim 2, Hshieh teaches the anode electrode includes a first anode electrode 18c brought into Schottky contact with an upper surface of the drift layer and a second anode electrode 18a brought into Schottky contact with the side surface of the center trench and made of a metal material (titanium) different from that (tungsten) of the first anode electrode. See Hshieh, FIG. 8, ¶ [0045].
As to claims 3 and 4, Hshieh does not teach inter alia the outer peripheral trench.
On the other hand, Arima teaches the drift layer further includes two outer peripheral trenches filled with anode electrode 40 and surrounding the center trench(es). See Arima, Annotated FIG. 3.
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Arima, Annotated FIG. 3
Note that Arima is only being relied upon to teach a multiplicity of identically formed trenches, and Arima’s particular trench structure, e.g. insulating material on an entirety of the sidewall of the trench, is not being relied upon.
Thus the combination of Hshieh and Arima forms four of Hshieh’s trenches in a same manner and the peripheral trenches are formed identically to the center trenches, wherein a bottom surface and an outer peripheral side surface of the outer peripheral trench is covered with an insulating film without being in contact with the anode electrode.
It would have been obvious to one of ordinary skill in the art before the effective filing date to incorporate the additional identically formed peripheral trenches as taught by Arima, with the center trench structures as taught by Hshieh, in order to yield the predictable benefit of minimizing the possibility of dielectric breakdown at corners of the anode electrode. Id. at ¶ [0010].
As to claims 5 and 6, the combination of Hshieh and Arima teaches at least part of an inner peripheral side surface of the outer peripheral trench is brought into Schottky contact with the anode electrode. See Arima, FIG. 3; Hshieh, FIG. 7.
No Prior Art Applied
The Examiner was unable to find prior art applicable to claims 7 and 8 as presently written.
As to claims 7 and 8, Hshieh teaches only center trenches filled with metal, not semiconductor material. While Arima teaches outer peripheral trenches formed identically to center trenches and filled with a semiconductor material having an opposite conductivity to the drift layer, Arima also teaches insulating material formed on an entire surface of the trench which teaches away from parent claim 1. It would not be obvious to selectively substitute the semiconductor material from Arima for the metal material of Hshieh. Furthermore, Arima’s identically formed center and outer peripheral trenches would not allow for metal material only in the center trenches and semiconductor material only in the outer peripheral trenches, if Arima is combined with Hshieh.
Prior Art Not Relied Upon
The following prior art was not relied upon but is made of record:
Goerlach et al. (U.S. Patent Publication No. 2009/0032897 A1)
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SUBERR CHI whose telephone number is (571)270-3955. The examiner can normally be reached 10am to 6pm.
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/SUBERR L CHI/Primary Examiner, Art Unit 2893
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