DETAILED ACTION
This Office Action is in response to RCE filed January 6, 2026.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claim 1 is objected to because of the following informalities: the limitation “the intrinsic 3C triangular defect is not exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 14-17, and the limitation “each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 20-23 should be amended, because while the intrinsic 3C triangular defect and the surface triangular defects may or may not appear in the surface microscope image, the intrinsic 3C triangular defect and the surface triangular defects are not objects that are or that are not exposed in the surface microscope image. Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-4, 6, 9, 12 and 13 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claims contain subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventors, at the time the application was filed, had possession of the claimed invention.
(1) Regarding claim 1, if “a same location” recited on lines 12 and 18 refer to the same, single location, then the amended claim 1 fails to comply with the written description requirement, because (a) Applicants did not originally disclose that the intrinsic 3C triangular defect and the surface triangular defects are observed in the “same location,” (b) Applicants did not use the word “location” in the original specification in the first place, not to mention the phrase “same location,” and (c) for example, Applicants observed only an intrinsic 3C triangular defect in Fig. 4 of current application, but no surface triangular defects are observed in the “same location.”
(2) Further regarding claim 1, Applicants did not originally disclose “the intrinsic 3C triangular defect is not exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 14-17, and “each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 20-23, because while Applicants originally disclosed a photoluminescence image, a TEM image and an X-ray image, Applicants did not originally disclose “a surface microscope image obtained by using a confocal microscope”.
Claims 2-4, 6, 9, 12 and 13 depend on claim 1, and therefore, claims 2-4, 6, 9, 12 and 13 also fail to comply with the written description requirement.
(3) Regarding claim 12, Applicants originally disclosed a surface triangular defect density of 0.05 pieces/cm2 in TABLE 3 of current application in comparison to a surface triangular defect density of 0.01 pieces/cm2 and 0.04 pieces/cm2 for Comparative Examples that are not directed Applicants’ invention, and TABLE 3 is the only place Applicants mentioned a value of a surface triangular defect density. Therefore, Applicants did not originally disclose the claimed surface triangular defect density of 0.05 pieces/cm2 or less, which encompasses a surface triangular defect density of both Applicants’ invention and Comparative Examples, and which can be, for example, 0.001 pieces/cm2 or 0.02 pieces/cm2, neither of which Applicants originally disclosed. Claim 13 depends on claim 12, and therefore, claim 13 also fails to comply with the written description requirement.
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 1-4, 6, 9, 12 and 13 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.
(1) Regarding claim 1, it is not clear what “the surface of the epitaxial layer” recited on line 12 refers to, because (a) Applicants do not claim “a surface of the epitaxial layer” before claiming “the surface of the epitaxial layer,” and (b) therefore, the limitation “the surface of the epitaxial layer” lacks the antecedent basis.
(2) Also regarding claim 1, it is not clear what “a same location on the surface of the epitaxial layer” recited on line 12 refers to, because (a) for Applicants to claim “a same location on the surface of the epitaxial layer”, Applicants first need to claim “a location on the surface of the epitaxial layer”, which Applicants do not claim, and (b) therefore, it is not clear where “a same location on the surface of the epitaxial layer” is located.
(3) Further regarding claim 1, it is not clear what the limitation “the intrinsic 3C triangular defect is not exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 14-17 suggests, and especially it is not clear what “a confocal microscope with a differential interference contrast system, SICA” refers to, because (a) as the attached Wilson reference (“The Origins and Development of the Confocal Scanning Microscope” (2015)) discloses, numerous types of confocal microscopes have been developed over a long period of time, (b) therefore, there are numerous magnifications and/or resolutions for the numerous types of confocal microscopes, (c) in this case, without Applicants’ specifically claiming what the claimed “confocal microscope” is, what its magnification and/or resolution is, who the manufacturer is, what the model number of the confocal microscope is, what the condition(s) is/are under which the claimed intrinsic 3C triangular defect is observed, etc., one would not be able to tell whether a non-observation of the claimed intrinsic 3C triangular defect by a certain confocal microscope means that there would not be any other confocal microscopes and differential interference contrast systems that would allow one to observe the claimed intrinsic 3C triangular defect that was not observed by the previously employed confocal microscope and differential interference control system, and (d) it appears that Applicants attempted to observe the claimed intrinsic 3C triangular defect once by a non-specific confocal optical microscope accompanied with a non-specific differential interference contrast system based on the original disclosure, and Applicants did not originally disclose that they used every single confocal microscope available and every single differential interference contrast system available at the time of the invention, in which case, what the claimed confocal microscope and the claimed differential contrast system that Applicants used for the claimed invention would be critical to the practice of the claimed invention, but Applicants do not claim what the claimed confocal microscope and the claimed differential contrast system that Applicants used for the claimed invention are.
(4) Still further regarding claim 1, it is not clear whether “a same location on the surface of the epitaxial layer” recited on line 18 refers to “a same location on the surface of the epitaxial layer” recited on line 12 or refers to another location on the surface of the epitaxial layer, and it is not clear whether “the surface of the epitaxial layer” recited on line 18 refers to “the surface of the epitaxial layer” recited on line 12, which the Examiner explained to be indefinite above.
(5) Still further regarding claim 1, it is not clear whether “a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 22-23 refers to “a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA” recited on lines 16-17 or refers to another surface microscope image.
(6) Still further regarding claim 1, it is not clear whether “a differential interference contrast system, SICA” in the limitation “a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA (emphasis added)” recited on lines 22-23 refers to “a differential interference contrast system, SICA” in the limitation “a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA” recited on lines 16-17 or refers to another differential interference contrast system, SICA.
Claims 2-4, 6, 9, 12 and 13 depend on claim 1, and therefore, claims 2-4, 6, 9, 12 and 13 are also indefinite.
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.
Claims 1, 2, 4, 6, 9, 12 and 13, as best understood, are rejected under 35 U.S.C. 103 as obvious over Ohno et al. (US 9,957,638) in view of Yazdanfar et al. (“Effect of process parameters on dislocation density in thick 4H-SiC epitaxial layers grown by chloride-based CVD on 4° off-axis substrates,” manuscript for “SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, 159-162 (2014).”) and further in view of Nishiguchi et al. (US 2016/0326668) and still further in view of Yamashita et al. (“Structural analysis of the 3C|4H boundaries formed on prismatic planes in 4H-SiC epitaxial films,” Journal of Crystal Growth 455 (2016) pp. 172-180) and yet still further in view of Sasaki et al. (US 10,269,554) and/or Tomita et al. (US 8,679,952)
In the below prior art rejection, the claim limitations “which glows with a photoluminescence light having a triangular shape and a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light” recited on lines 13-14 of claim 1, “the intrinsic 3C triangular defect is not exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA” recited on lines 14-17 of the amended claim 1, and “each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA” recited on lines 20-23 of the amended claim 1 specify intended uses or fields of use, and are treated as non-limiting since it has been held that in device claims, intended use must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim. In re Casey, 152 USPQ 235 (CCPA 1967); In re Otto, 136 USPQ 458, 459 (CCPA 1963). A claim containing a “recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus” if the prior art apparatus teaches all the structural limitations of the claim. Ex Parte Masham, 2 USPQ 2d 1647 (Bd. Pat. App. & Inter. 1987).
Regarding claim 1, Ohno et al. disclose a SiC epitaxial wafer (Fig. 7) comprising: a SiC single crystal substrate (4H-SiC SUBSTRATE) of which a main surface has an off-angle of 0.4° to 5° with respect to (0001) plane in a <11-20> direction (col. 3, lines 17-19); and an epitaxial layer (EPITAXIAL LAYER) provided on the SiC single crystal substrate, wherein the epitaxial layer has an intrinsic 3C triangular defect density of 0.1 pieces/cm2 or less (SiC epitaxial wafers corresponding to one of four (B) samples in Fig. 4), because (a) Fig. 7 shows a formation mechanism of an intrinsic 3C triangular defect Applicants originally disclosed in paragraphs [0070] and [0082] of current application as previously discussed under 35 USC 112(b) rejections in the Non Final Office Action mailed September 15, 2022, and (b) whether or not the four (B) samples are measured for 3C triangular defects, when the entire triangular defects have a density of 0.1 pieces/cm2 or less, the intrinsic 3C triangular defect density would also have a density of 0.1 pieces/cm2 or less, and when a same location on the surface of the epitaxial layer is observed, which is indefinite as discussed above under 35 USC 112(b) rejections, the intrinsic 3C triangular defect is a defect which glows with a photoluminescence light having a triangular shape and a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, which is inherent since (i) Ohno et al. disclose the mechanism of generating the intrinsic 3C triangular defect Applicants originally disclosed as discussed above, (ii) the claimed glowing photoluminescence light having the triangular shape in the claimed wavelength range by UV is an inherent characteristic of the intrinsic 3C triangular defect as Applicants originally disclosed, and (iii) if the intrinsic 3C triangular defect disclosed by Ohno et al. does not exhibit the claimed glowing photoluminescence in the claimed wavelength range by UV, then claim 1 would be further indefinite for not claiming an essential and critical feature to the practice of the claimed invention, and which is also directed to an intended use or an optical measurement of the SiC epitaxial layer as discussed above, and the intrinsic 3C triangular defect is not exposed in a surface microscope image obtained by using a confocal microscope with a differential interference contrast system, SICA, which is indefinite as discussed above under 35 USC 112(b) rejections, and which should also be inherent since (i) Ohno et al. disclose the mechanism of generating the intrinsic 3C triangular defect Applicants originally disclosed as discussed above, (ii) the claimed non-observation of the intrinsic 3C triangular defect is an inherent characteristic of the intrinsic 3C triangular defect as Applicants originally disclosed, and (iii) if the intrinsic 3C triangular defect disclosed by Ohno et al. is observed as a defect by a confocal microscope, then claim 1 would be further indefinite for not claiming an essential and critical feature to the practice of the claimed invention.
Ohno et al. differ from the claimed invention by not showing that the epitaxial layer has a basal plane dislocation density of 0.1 pieces/cm2 or less where the basal plane dislocation density is a density of basal plane dislocations extending from the SiC single crystal substrate to a top surface of the epitaxial layer, the epitaxial layer includes surface triangular defects, a diameter of the SiC single crystal substrate is 150 mm or more, the intrinsic 3C triangular defect is a defect including a 3C polytype inside the epitaxial layer, and when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA.
Yazdanfar et al. disclose a SiC epitaxial wafer (Title and Abstract) comprising: a SiC single crystal substrate (4H-SiC) of which a main surface has an off-angle of 0.4° to 5° in <11-20> direction (lines 2-4 under Experimental), and an epitaxial layer provided on the SiC single crystal substrate, wherein the epitaxial layer has a basal plane dislocation density of 0.1 pieces/cm2 or less (0 for C/Si = 0.6 or 0.7 in Fig. 3, and line 9 of first paragraph under Fig. 3) where the basal plane dislocation density is a density of basal plane dislocations extending from the SiC single crystal substrate (Abstract) to a top surface of the epitaxial layer (last sentence of Abstract).
Since both Ohno et al. and Yazdanfar et al. teach a SiC epitaxial wafer, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the epitaxial layer disclosed by Ohno et al. can have a basal plane dislocation density of 0.1 pieces/cm2 or less, because (a) a density of dislocations including a density of basal plane dislocations is what one of ordinary skill in the art has been striving to reduce during an epitaxial growth of semiconductor materials including SiC such that semiconductor layers formed on the semiconductor materials would have a less defect density, and semiconductor devices formed on the semiconductor materials would have better performance, (b) Yazdanfar et al. disclose a method of forming an epitaxial SiC wafer where the basal dislocation density can be reduced, and (c) the claim is prima facie obvious without showing that the claimed range of the basal plane dislocation density achieves unexpected results relative to the prior art range. In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Huang, 40 USPQ2d 1685, 1688 (Fed. Cir. 1996) (claimed ranges of a result effective variable, which do not overlap the prior art ranges, are unpatentable unless they produce a new and unexpected result which is different in kind and not merely in degree from the results of the prior art). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art) and In re Aller, 105 USPQ 233 (CCPA 1955) (selection of optimum ranges within prior art general conditions is obvious).
Further regarding claim 1, Ohno et al. in view of Yazdanfar et al. differ from the claimed invention by not showing that the epitaxial layer includes surface triangular defects, a diameter of the SiC single crystal substrate is 150 mm or more, the intrinsic 3C triangular defect is a defect including a 3C polytype inside the epitaxial layer, and when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA.
Yazdanfar et al. disclose that the substrates are 1.5 × 1.5 cm2 (lines 2-3 under Experimental).
In addition, Nishiguchi et al. disclose a SiC epitaxial wafer (Fig. 1), where a diameter of a SiC single crystal substrate is 150 mm or more (diameter not less than 150 mm in [0033]).
Since both Ohno et al. and Nishiguchi et al. teach a SiC epitaxial wafer, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the diameter of the SiC single crystal substrate can be within the claimed range, because (a) a SiC substrate having a diameter of 150 mm or more has been well-known and commonly used as disclosed by Nishiguchi et al., (b) a larger diameter substrate has been commonly employed in semiconductor industry such that more semiconductor devices can be formed on a single substrate, which would reduce the manufacturing cost, and (c) the claim is prima facie obvious without showing that the claimed range of the diameter of the SiC substrate achieves unexpected results relative to the prior art range. In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Huang, 40 USPQ2d 1685, 1688 (Fed. Cir. 1996) (claimed ranges of a result effective variable, which do not overlap the prior art ranges, are unpatentable unless they produce a new and unexpected result which is different in kind and not merely in degree from the results of the prior art). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art) and In re Aller, 105 USPQ 233 (CCPA 1955) (selection of optimum ranges within prior art general conditions is obvious).
Still further regarding claim 1, Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. differ from the claimed invention by not showing that the epitaxial layer includes surface triangular defects, the intrinsic 3C triangular defect is a defect including a 3C polytype inside the epitaxial layer, and when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA.
Yamashita et al. disclose a SiC epitaxial wafer (Title) comprising an intrinsic 3C triangular defect (Fig. 2(a)) which is a defect including a 3C polytype inside the epitaxial layer.
Since both Ohno et al. and Yamashita et al. teach a SiC epitaxial wafer, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the intrinsic 3C triangular defect disclosed by Ohno et al. can be a defect including a 3C polytype inside the epitaxial layer as disclosed by Yamashita et al., because (a) both Ohno et al. and Yamashita et al. disclose a SiC single crystal substrate having the same polytype and offcut angle, (b) therefore, the intrinsic 3C triangular defect disclosed by Ohno et al. can have the structure of the intrinsic 3C triangular defect disclosed by Yamashita et al. with the 3C polytype region during the epitaxial growth of the epitaxial layer, especially when the growth parameters disclosed by Ohno et al. and Yamashita et al. are (substantially) identical, since the claimed configuration of the 3C polytype triangular defect surrounded by the 4H polytype regions has been a commonly observed phenomenon as explained by Yamashita et al., and (c) in other words, when the epitaxial layer is primarily of the 4H polytype, the triangular defect having a 3C polytype would be surrounded by the 4H polytype region(s) in the epitaxial layer.
Still further regarding claim 1, Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. differ from the claimed invention by not showing that the epitaxial layer includes surface triangular defects, and when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA.
(I) Sasaki et al. disclose that “A triangular defect is a defect that is formed with a characteristic surface morphology on the surface of an epitaxial layer on a vicinal SiC single crystal substrate having an off angle” on lines 50-53 of column 1.
(II) Tomita et al. disclose that “FIG. 2 is a result of optical microscope observation under a dark field on the SiC bulk substrate top surface after the above described process”, and that “As will be described later, triangular defects are observed at areas enclosed with solid lines after epitaxial growth, while carrot defects are observed at areas enclosed with dotted lines” on lines 50-55 of column 7.
Since both Ohno et al. and Sasaki et al./Tomita et al. teach a SiC epitaxial wafer, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the epitaxial layer disclosed by Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. can include surface triangular defects, and when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA, because (a) as Sasaki et al. and Tomita et al. disclose, a surface triangular defect has been always or at least a commonly observed surface defect on an epitaxially grown silicon carbide layer on a silicon carbide substrate having a vicinal surface Applicants originally disclosed and as Ohno et al. also disclose, (b) a plurality of surface triangular defects would be formed especially when the epitaxial layer has a large surface area, which would have been obvious since a larger wafer and a larger epitaxial layer would allow forming more semiconductor devices, reducing the manufacturing cost, (c) a surface triangular defect with the claimed photoluminescence characteristic has been commonly observed by an optical microscope as Applicants originally disclosed and as Tomita et al. disclose, and (d) the limitations “when a same location on the surface of the epitaxial layer is observed, each of the surface triangular defects is a defect which does not glow with a photoluminescence light having a wavelength of 540 nm to 600 nm when irradiated with ultraviolet light, and each of the surface triangular defects is a defect having a triangular shape which is exposed in a surface microscope image obtained by using the confocal microscope with a differential interference contrast system, SICA” are directed to intended uses as discussed above, especially when Applicants do not specifically claim what the “confocal microscope” refers to, and how the confocal microscope is employed in observation of the claimed surface triangular defect.
Regarding claim 2, Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. further disclose that in the epitaxial layer, a basal plane dislocation density in a first region on a SiC single crystal substrate side is inherently higher than a basal plane dislocation density in a second region on a top surface side (last sentence of Abstract of Yazdanfar et al.), because (a) Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. satisfy all the other claim limitations, (b) Yazdanfar et al. also disclose reduction of basal plane dislocation density, which suggests that the number of the basal plane dislocations that extend from the SiC single crystal substrate is reduced, and the top surface of the epitaxial layer shows zero basal plane dislocations for the ratio of C/Si of 0.6 or 0.7 in Fig. 3, (c) in other words, the interface region of the SiC single crystal substrate and the epitaxial layer would have a higher basal plane dislocation density since there are a lot more basal dislocations in the SiC single crystal substrate, and (d) if Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. do not meet the claim limitation of claim 2, then claim 2 would be indefinite since Applicants do not specifically claim a critical and essential feature to the practice of the claimed invention.
Regarding claim 4, Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. further disclose that and a thickness of the first region is 1 µm or less, because (a) Applicants do not specifically claim what “the first region” refers to, and how it is defined, and (b) therefore, a bottommost arbitrary portion of the epitaxial layer that has the claimed thickness can be referred to as the first region.
Regarding claim 6, Ohno et al. further disclose for the SiC epitaxial wafer according to claim 1 that a thickness of the epitaxial layer is 10 µm or more and 400 µm or less (10 µm on lines 5-7 of column 4).
Regarding claim 9, Yazdanfar et al. further disclose for the SiC epitaxial wafer according to claim 4 that the basal plane dislocation density of the first region is 10 or more times greater than the basal plane dislocation density of the second region, because (a) there inherently are basal plane dislocations in the first region as implied on the last line of Abstract, and there are zero dislocations in the second region for the C/Si ratio of 0.6 or 0.7 as shown in Fig. 3, and (b) therefore, the claim limitation would be met automatically since any number is 10 or more times greater than zero.
Claim 3, as best understood, is rejected under 35 U.S.C. 103 as being unpatentable over Ohno et al. (US 9,957,638) in view of Yazdanfar et al. (“Effect of process parameters on dislocation density in thick 4H-SiC epitaxial layers grown by chloride-based CVD on 4° off-axis substrates,” manuscript for “SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2, 159-162 (2014).”) further in view of Nishiguchi et al. (US 2016/0326668) and still further in view of Yamashita et al. (“Structural analysis of the 3C|4H boundaries formed on prismatic planes in 4H-SiC epitaxial films,” Journal of Crystal Growth 455 (2016) pp. 172-180) and yet still further in view of Sasaki et al. (US 10,269,554) and/or Tomita et al. (US 8,679,952) as applied to claim 2 above, and further in view of Myers-Ward et al. (“Spontaneous Conversion of Basal Plane Dislocations in 4° Off-Axis 4H-SiC Epitaxial Layers, Crystal Growth & Design 14 (2014) pp. 5331-5338.) The teachings of Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. are discussed above.
Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. and yet still further in view of Sasaki et al. and/or Tomita et al. differ from the claimed invention by not showing that the SiC single crystal substrate and the epitaxial layer have the same conductivity type, the epitaxial layer includes a buffer layer and a drift layer from the SiC single crystal substrate side in this order, a carrier concentration of the buffer layer is higher than a carrier concentration of the drift layer, and the buffer layer includes the first region.
Myers-Ward et al. disclose that a SiC single crystal substrate and an epitaxial layer have the same conductivity type (Fig. 7), the epitaxial layer includes a buffer layer and a drift layer from the SiC single crystal substrate side in this order, a carrier concentration of the buffer layer is higher than a carrier concentration of the drift layer, and the buffer layer includes the first region (Fig. 7).
Since both Ohno et al. and Myers-Ward et al. teach an SiC epitaxial wafer, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the claimed configuration can be formed in the SiC epitaxial wafer disclosed by Ohno et al. in view of Yazdanfar et al. and further in view of Nishiguchi et al. and still further in view of Yamashita et al. as disclosed by Myers-Ward et al., because the SiC epitaxial wafer disclosed by Ohno et al. in view of Yazdanfar et al. and further in view of Nishguchi et al. and still further in view of Yamashita et al. can be employed to form the device structure shown in Fig. 7 of Myers-Ward et al. as one of its applications.
Response to Arguments
Applicants’ arguments with respect to claim 1 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument, especially because Applicants’ arguments in the REMARKS filed January 6, 2026 are primarily about the newly added limitations in the amended claim 1, which fail to comply with the written description requirement and are also indefinite as discussed above under 35 USC 112(a) and 112(b) rejections discussed above.
The followings are the responses that the Examiner made in the Final Office Action mailed July 16, 2025 that are still relevant to the Applicants’ arguments filed January 6, 2026, because Applicants still made the same arguments about the teachings of the prior art references:
“Applicants argue on page 6 of the REMARKS filed June 27, 2025 that “Therefore, the intrinsic 3C triangular defect is not observed by an optical microscope even with a larger magnification.” This argument is a mere allegation without any substantiating evidence, and thus is not persuasive, because (a) Applicants did not originally disclose the sizes and number of the intrinsic 3C triangular defects that they observed, (b) Applicants did not originally disclose the magnification and resolution of the optical microscope that they used, and (c) therefore, even at the time of the invention, some intrinsic 3C triangular defects could have been observed by an optical microscope with a better resolution and magnification; to help Applicants understand advancement of optical science, the Examiner would like to point out advancement of lithography machines ASML has been developing by employing advanced optics over the past decades, and Applicants should be able to understand that what can be observed by “an optical microscope” is not fixed over time.
Applicants’ arguments on page 7 of the REMARKS citing Kageshima are not persuasive, because Applicants made allegations without providing any evidence that the triangular defect observed by Kageshima et al. is not the claimed intrinsic 3C triangular defect.
Applicants argue that “The cited references do pat teach or suggest the claimed intrinsic triangular defect”, that “The features regarding the intrinsic 3C triangular defects are not intended uses or fields of use but are the structural differences between the claimed invention and the cited references”, that “In the cited references, there is no description or suggestion of the features regarding the intrinsic 3C triangular defects”, that “Specifically, the triangular defect described in Ohno and the triangular defect described in Yamashita are surface triangular defects described in paragraph [0069] of US2019/0376206A1 (publication of the present application)”, that “As shown in FIG. 6 of Ohno and FIG. 2 of Yamashita, a 3C polytype included in the triangular defect is positioned above a 4H epitaxial layer, and the 3C polytype is not positioned between a 4H epitaxial layer on an upper side and a 4H epitaxial layer on a lower side”, and that “In contrast, in the claimed invention, the intrinsic 3C polytype triangular defect is positioned between a 4H epitaxial layer on an upper side and a 4H epitaxial layer on a lower side.” These arguments are not persuasive, because (a) as the Examiner has noted before during the prosecution of current application, Ohno et al. reference discloses the same epitaxial growth mechanism as Applicants originally disclosed for current application, and therefore, Ohno et al. should inherently disclose the claimed intrinsic 3C triangular defects, (b) Applicants do not claim that “the intrinsic 3C polytype triangular defect is positioned between a 4H epitaxial layer on an upper side and a 4H epitaxial layer on a lower side” contrary to Applicants’ arguments above, and (c) it also appears that Applicants’ arguments above are directed to attacking the teachings of the individual references, and in response to Applicants' arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
Finally, the Examiner would like to note that he provided the following responses in the Non Final Office Action mailed March 31, 2025, which would still be relevant to Applicants’ arguments above:
“Applicants’ arguments traversing the previously made 35 USC 112(b) rejection of claim 11, which is previously and currently cancelled, involving the non-observation of the claimed intrinsic 3C triangular defect “by an optical microscope” on pages 7-8 of the REMARKS filed December 11, 2023 are not persuasive, because (a) the claimed non-observation of the claimed intrinsic 3C triangular defect would depend on numerous parameters including (i) the size of the claimed intrinsic 3C triangular defect, (ii) the magnification of the claimed but unspecified optical microscope which is closely related to the size of the claimed intrinsic 3C when it comes to its observation since, when the claimed intrinsic 3C triangular defect is large enough to be, for example, 200 nm, 500 nm or 1 µm, the claimed intrinsic 3C triangular defect can be observed by an optical microscope with a large magnification, and (iii) the illumination condition for the observation by the optical microscope, and (b) while an observation of a defect generally needs only one good observation of the defect, a non-observation of a defect cannot be generally translated into a general concept or a fact that the defect cannot be observed under any circumstances since one cannot prove a negative in almost all the cases, i.e. a non-observation of the defect by one optical microscope with one magnification does not necessarily suggest a non-observation of the same defect by any optical microscope with a larger magnification, and even by an optical microscope that will be developed in the future.”
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Wada et al. (US 10,490,634)
Nishiguchi et al. (US 2018/0233562)
Yamashita et al., “Characteristic morphologies of triangular defects on Si-face 4H-SiC epitaxial films,” Journal of Crystal Growth 433 (2016) pp. 97-104.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JAY C KIM whose telephone number is (571) 270-1620. The examiner can normally be reached 8:00 AM - 6:00 PM EST.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua Benitez can be reached on (571) 270-1435. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/JAY C KIM/Primary Examiner, Art Unit 2815
/J. K./Primary Examiner, Art Unit 2815 May 21, 2026
Prosecution Insights