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 1-5 in the reply filed on 07/13/2026 is acknowledged.
Claims 6-8 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim.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 07/13/2026.
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.
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.
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) 1-5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Sanchez et al (“Formation of Thermal Decomposition Cavities in Physical Vapor Transport of Silicon Carbide” from IDS filed 04/22/2024) in view of Nishihara et al (US 2020/0251561).
Sanchez et al teaches micropipes constituted by cylindrical voids having diameters of 0.1 µm to 5 µm, and thermal decomposition cavities having diameters of 5 µm to 100 µm are present in a silicon carbide (SiC) that has been grown by sublimation, and the thermal decomposition cavities have tapered tubular forms when viewed under a microscope, wherein the depth of the thermal decomposition cavity has a depth greater than the width (Fig 1; pg 347-348), which clearly suggests a width of the void is 10 µm to 80 µm when viewed in a direction perpendicular to the first main surface, in a cross section perpendicular to the first main surface, the width of the void decreases from the first main surface toward the second main surface when viewed in a direction parallel to the first main surface, a depth of the void is larger than or equal to the width of the void in the first main surface and smaller than a thickness of the silicon carbide substrate when viewed in the direction parallel to the first main surface . Overlapping ranges are prima facie obvious (MPEP 2144.05).
Sanchez et al does not explicitly teach the area density of the void in the first main surface is 0.7/cm2 or less.
In a SiC wafer, Nishihara et al teaches a “large-pit defect” refers to a defect having the following characteristics when an inspection apparatus, the defect appears a dent or hole having a size (maximum distance when connecting two points on the outer circumference of the image with a straight line) of 5 μm or more; defects that are pits or holes with a size of 15 μm or more in the SICA image and appear bright in the PL image at the same size or larger than the size in the microscope image, empirically, about 100% of the defects are caused by substrate carbon inclusions or micropipes in the substrate; large-pit defect in the SiC epitaxial wafer shown in FIG. 2 has a circular shape with a diameter of about 15 μm in the SICA image and a circular shape with a diameter of about 20 to 30 μm in the PL image; and the total density of large-pit defects caused by micropipes in the substrate and large-pit defects caused by substrate carbon inclusions is preferably 0.5 defect/ cm2 or less, 0.1 defect/ cm2 or less, it is more preferably 0.01 defect/ cm2or less, and it is even more preferably 0 defect/ cm2or less ([0020]-[0065]). Nishihara et al teaches the SiC wafer preferably has an off angle of 0.4° or more to 8° or less; and a SiC single crystal substrates with a diameter of 3 to 6 inches (~76-152mm) ([0034]-[0036]).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Sanchez et al by minimizing both voids and the micropipe density to less than 0.1 defect/ cm2 or less, as taught by Nishihara et al to reduce defects. Overlapping ranges are prima facie obvious (MPEP 2144.05).
Referring to claim 2, the combination of Sanchez et al and Nishihara et al teaches a total density of large-pit defects caused by micropipes in the substrate and large-pit defects caused by substrate carbon inclusions, both of which are contained in the SiC epitaxial layer, is 1 defect/cm2 or less, preferably 0.1 defect/ cm2or less (Nishihara [0020], [0049]). Overlapping ranges are prima facie obvious (MPEP 2144.05).
Referring to claim 3, the combination of Sanchez et al and Nishihara et al teaches a density of the large-pit defects caused by micropipes in the substrate is 0.5 defect/ cm2 or less; and a total density of large-pit defects caused by micropipes in the substrate and large-pit defects caused by substrate carbon inclusions, both of which are contained in the SiC epitaxial layer, is 1 defect/cm2 or less, preferably 0.1 defect/ cm2or less (Nishihara [0020]-[0021], [0049]). Overlapping ranges are prima facie obvious (MPEP 2144.05).
Referring to claim 4, the combination of Sanchez et al and Nishihara et al teaches a SiC single crystal substrate with a diameter of 3 to 6 inches (~76-152mm) ([0034]-[0036]).
Referring to claim 5, the combination of Sanchez et al and Nishihara et al teaches the SiC wafer preferably has an off angle of 0.4° or more to 8° or less (Nishihara [0034]-[0036]).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Guo et al (US 2019/0187068) teaches a SiC epitaxial wafer in which a SiC epitaxial layer is formed on a 4H—SiC single crystal substrate having an off angle and a substrate carbon inclusion density of 0.1 to 6.0 inclusions/ cm2, and wherein a density of large pit defects caused by substrate carbon inclusions and contained in the SiC epitaxial layer is 0.5 defects/ cm2 or less; and size of the large pit defect is typically from 200 to 500 μm2 (Abstract; [0059]).
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MATTHEW J SONG whose telephone number is (571)272-1468. The examiner can normally be reached Monday-Friday 10AM-6PM.
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MATTHEW J. SONG
Examiner
Art Unit 1714
/MATTHEW J SONG/Primary Examiner, Art Unit 1714
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