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 .
DETAILED ACTION
Preliminary amendment, received 12/22/2023, has been entered.
Claims 1-14 are presented for examination.
Claim Rejections - 35 USC § 103
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.
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.
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) 1-8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Asamizu (US Pub. No. 2018/0202070 A1), in view of Wada et al. (US Pub. No. 2018/0363166 A1), hereafter referred to as Wada.
As to claim 1, Asamizu discloses a silicon carbide epitaxial substrate (fig 1B, 1; [0089]) comprising:
a silicon carbide substrate (fig 1B, substrate 2; [0066]);
a silicon carbide epitaxial layer (fig 1B, layer 3; [0089]) located on the silicon carbide substrate (2); and
a bump ([0239]) formed on the silicon carbide epitaxial layer (3),
wherein the silicon carbide epitaxial layer (3) includes a main surface (top) located opposite to a boundary surface (bottom) between the silicon carbide substrate (2) and the silicon carbide epitaxial layer (3), and a drift layer that constitutes the main surface ([0018]),
an area density of the bump is 1.0/cm2 or less on the main surface ([0089]),
a polytype of silicon carbide of the bump is the same as a polytype of silicon carbide of the silicon carbide epitaxial layer ([0239]).
Asamizu does not disclose the height or diameter of the bump defect, therefore Asamizu does not disclose that the a height of the bump is 50 nm or more, and a diameter of the bump is 5um or more and 30um or less.
Nonetheless, Wada discloses wherein a bump defect in a silicon carbide epitaxial substrate is defined with a diameter of more than or equal to 10um ([0116]) and a height of more than several ten nanometer ([0116]).
It would have been obvious to one of ordinary skill in the art before the effective filing of the claimed invention to define the height and diameter of the bump defect of Asamizu within the claimed range as taught by Wada since this will enable the characterization of defects that effect device quality without quantifying defects that are below the defect size threshold.
As to claim 2, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 1 (paragraphs above).
Asamizu further discloses wherein an in-plane uniformity of a carrier concentration in the drift layer is 15% or less ([0088]).
As to claim 3, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 1 (paragraphs above).
Asamizu further discloses wherein an in-plane uniformity of a carrier concentration in the drift layer is 7% or less ([0155]).
As to claim 4, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 1 (paragraphs above).
Asamizu further discloses wherein a diameter of the main surface is 150 mm or more ([0118]).
As to claim 5, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 1 (paragraphs above).
Asamizu further discloses wherein the area density of the bump is 0.5 /cm2 or less ([0089]).
As to claim 6, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 1 (paragraphs above).
Asamizu further discloses wherein an in-plane uniformity of a thickness of the drift layer is 5% or less ([0153]).
As to claim 7, Asamizu in view of Wada disclose the silicon carbide epitaxial substrate according to claim 6 (paragraphs above).
Asamizu further discloses wherein the in-plane uniformity of the thickness of the drift layer is 3% or less ([0153]).
As to claim 8, Asamizu discloses a method of manufacturing a silicon carbide semiconductor device ([0011]), the method comprising:
preparing the silicon carbide epitaxial substrate according to claim 1 (paragraphs above); and
processing the silicon carbide epitaxial substrate ([0333]-[0334]).
Allowable Subject Matter
Claims 9-14 are allowed.
The following is a statement of reasons for the indication of allowable subject matter: The prior art of record fails to teach or suggest all of the limitations of independent claim 9. Specifically, neither of the closest prior art references Asamizu or Wada et al. (US Pub. No. 2019/0019868A1) teach or suggest forming a surface-modified layer on the silicon carbide epitaxial layer under a condition of a second C/Si ratio; and removing the surface-modified layer by hydrogen etching, wherein the second C/Si ratio is less than the first C/Si ratio, as recited in claim 9. Dependent claims 10-14 are allowable because of their dependence from claim 9.
Pertinent Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Wada et al. (US Pub. No. 2019/0019868A1) teaches forming a first silicon carbide epitaxial layer with a C/Si ratio and a surface modified layer with a lower C/Si ratio but fails to teach wherein the surface modified layer is removed by hydrogen etching.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SHAUN M CAMPBELL whose telephone number is (571)270-3830. The examiner can normally be reached on MWFS: 7:30-6pm Thurs 1-2pm.
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/SHAUN M CAMPBELL/Primary Examiner, Art Unit 2893 4/23/2026
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