DETAILED ACTION
This Office Action is in response to Amendment filed May 18, 2026.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Drawings
The drawings were received on May 18, 2026. These drawings are accepted.
Claim Objections
Claims 1 and 15 are objected to because of the following informalities:
On lines 11-12 of claim 1 and on line 11 of claim 15, “concentration of carbon impurities” should be replaced with “a concentration of the carbon impurities”.
On line 12 of claims 1 and 15, “concentration of iron impurities” should be replaced with “a concentration of the iron impurities”.
On lines 16-17 of claims 1 and 15, “concentration of carbon impurities” should be replaced with “a concentration of the carbon impurities”.
On line 20 of claims 1 and 15, “concentration of carbon impurities” should be replaced with “a concentration of the carbon impurities”.
On lines 20-21 of claims 1 and 15, “the concentration of carbon impurities” should be replaced with “the concentration of the carbon impurities”.
On line 23 of claim 1, “the concentration of carbon impurities” should be replaced with “the concentration of the carbon impurities”.
Appropriate correction is required.
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.
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, 3, 4, 7-9 and 15-19 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 claims 1 and 15, it is not clear what the limitation “the first buffer layer and the third buffer layer are not actively doped with iron impurities (emphasis added)” recited on lines 8-9 of claims 1 and 15 suggests, because (a) the claimed invention is directed to “An epitaxial structure of a semiconductor device” rather than a method of forming an epitaxial structure of a semiconductor device, (b) it is not clear whether the phrase “not actively doped” suggests “undoped”, “passively doped” or “unintentionally doped”, (c) it is not clear whether the phrase “not actively doped” is directed to Applicants’ intention or design, but the actual concentration of iron impurities included in the first and third buffer layer in the final structure of the claimed epitaxial structure was not measured or is unknown, (d) depending on how the phrase “not actively doped” is interpreted, the first and third buffer layer may or may not be doped with iron impurities, and the concentration of the iron impurities included in the first and third buffer layer would also vary, (e) for example, as Fig. 4 of Ishiguro et al. (US 10,431,656) shows, when an undoped semiconductor layer, i.e. GaN, is in contact with a semiconductor layer doped with iron, i.e. GaN:Fe, the iron impurities can diffuse out of the semiconductor layer doped with iron, (f) also, whether the iron impurities diffuse out of the second buffer layer doped with iron impurities, and to what extent the iron impurities diffuse out of the second buffer layer into the neighboring first and third buffer layer would depend on numerous conditions such as (i) the growth temperatures of the first, second and third buffer layer, (ii) the material compositions of the first, second and third semiconductor layer, (iii) whether the semiconductor structure has been annealed during the manufacturing process, (iv) how the first, second and third buffer layer were deposited, etc. (two examples of different amounts of diffusion of iron impurities are also shown in Fig. 4 of Ishiguro et al. (US 10,431,656)), none of which Applicants claim in claim 1, and (g) therefore, the limitation “the first buffer layer and the third buffer layer are not actively doped with iron impurities (emphasis added)” recited on lines 8-9 of claims 1 and 15 does not specify (i) whether the first and third buffer layer are doped with iron impurities or not, and (ii) if the first and second buffer layer are doped with iron impurities passively or unintentionally, how the iron impurities are distributed inside the first and third buffer layer. Claims 3, 4 and 7-9 depend on claim 1, and claims 16-18 depend on claim 15, and therefore, claims 2-9 and 16-18 are also indefinite.
(2) Regarding claim 19, it is not clear how claim 19 depends on claim 19, because a claim cannot dependent on itself.
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 15, 16 and 19, as best understood, are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Cordier et al. (“Subsurface Fe-doped semi-insulating GaN templates for inhibition of regrowth interface pollution in AlGaN/GaN HEMT structures,” Journal of Crystal Growth 310 (2008) pp. 948-954)
The claim limitation “buffer” specifies an intended use or field of use, and is 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 15, Cordier et al. disclose an epitaxial structure (MD or CD in Fig. 2) (first paragraph under 2. Experimental procedure on page 949) of a semiconductor device (HEMT in Title), the structure comprising: a substrate (Sapphire); and a first semiconductor layer (composite layer formed on Sapphire) located on the substrate, the first semiconductor layer comprising buffer layers (layers between Sapphire and thicker GaN ud), the buffer layers at least comprising a first buffer layer (top portion of SI - GaN), because (a) Applicants do not specifically claim what the first buffer layer refers to, and what its surrounding layers are, and (b) therefore, the top portion of the SI-GaN layer having a thickness in a range of 200 nm to 800 nm, which is recited on the last two lines of claim 15, can be referred to as a first buffer layer with the bottom or remainder portion of the SI-GaN layer being referred to as a nucleation layer, an underlying layer, an intermediate layer or an insertion layer, a second buffer layer (Fe:N in MD or GaN:Fe in CD), and a third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) which are arranged in layers, and the second buffer layer being located between the first buffer layer and the third buffer layer; wherein the second buffer layer (Fe:N in MD or GaN:Fe in CD) is doped with iron impurities, and wherein the first buffer layer (top portion of SI - GaN) and the third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) are not actively doped with iron impurities, because (a) as discussed above under 35 USC 112(b) rejection, it is not clear what the phrase “not actively doped” suggests, and (b) therefore, the top portion of the SI - GaN layer and the GaN ud layer with a thickness of 100 nm or 90 nm can respectively be referred to as the first and third buffer layer that “are not actively doped with iron impurities”, wherein the second buffer layer (Fe:N in MD or GaN:Fe in CD) is further doped with carbon impurities (Fig. 3(a)), and wherein concentration of carbon impurities of the second buffer layer is less than concentration of iron impurities of the second buffer layer (Fig. 3(b)), because the concentration of iron impurities in the second buffer layer is about 1019 cm-3 as shown in Fig. 3(b), while the concentration of carbon impurities in the second buffer layer is below 1017 cm-2 as shown in Fig. 3(a), wherein the first buffer layer (top portion of SI - GaN) is located on a side of the second buffer layer (Fe:N in MD or GaN:Fe in CD) close to the substrate (Sapphire), and wherein the third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) is located on a side of the second buffer layer close to a second semiconductor layer (thicker GaN ud or AlGaN); wherein, wherein the first buffer layer has carbon impurities (Fig. 3(a)), and wherein concentration of carbon impurities of the first buffer layer (top portion of SI - GaN) is less than or equal to the concentration of carbon impurities of the second buffer layer (Fe:N in MD or GaN:Fe in CD), because (a) Applicants do not specifically claim where the claimed concentrations of carbon impurities are measured, and (b) therefore, when the claimed concentrations of carbon impurities can be measured at their interface, the two claimed concentrations of carbon impurities would be equal to each other; and wherein the third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) has carbon impurities (Fig. 3(a)), and wherein concentration of carbon impurities of the third buffer layer is less than the concentration of carbon impurities of the second buffer layer, because (a) Applicants do not specifically claim where the claimed concentrations of carbon impurities are measured, and (b) therefore, the claimed concentrations of carbon impurities can be selected from arbitrary regions of the second and third buffer layer in Fig. 3(a) to satisfy the claim limitation, wherein the thickness of the first buffer layer (top portion of SI – GaN with a thickness of 200 nm - 800 nm) is d1, and wherein 200nm≤d1≤800nm.
Cordier et al. differ from the claimed invention by not showing that the thickness of the third buffer layer is d3, wherein 200nm≤d3≤500nm.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the thickness of the third buffer layer can be in the claimed range, because (a) the thickness of the third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) can be controlled and optimized to improve quality of the GaN ud layer, which would in turn improve performance of the HEMT disclosed by Cordier et al., since a thicker buffer layer would help improve quality of the semiconductor layer(s) deposited on the thicker buffer layer, while also controlling and optimizing the overall thickness of the semiconductor device, and (b) the claim is prima facie obvious without showing that the claimed range of the thickness of the third buffer layer 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).
Regarding claim 16, Cordier et al. further disclose that the concentration of carbon impurities of the second buffer layer (Fe:N in MD or GaN:Fe in CD) satisfies a second preset range, and wherein the second preset range is 10¹⁶ cm-3 ~ 10¹⁷ cm-3, see Fig. 3(a).
Cordier et al. differ from the claimed invention by not showing that the concentration of iron impurities of the second buffer layer satisfies a first preset range, wherein the first preset range is 10¹⁶ cm-3 ~ 5·1018 cm-3.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the concentration of iron impurities of the second buffer layer can satisfy a first preset range, wherein the first preset range can be 10¹⁶ cm-3 ~ 5·1018 cm-3, because (a) the concentration of iron impurities shown in Fig. 3(b) of Cordier et al. is approximately around 5·1018 cm-3, and (b) the concentration of iron impurities should be controlled and optimized to obtain desired insulating characteristics and dielectric constant of the overall buffer layer structure of Cordier et al.
Regarding claim 19, Cordier et al. further disclose that the concentration of iron impurities in the third buffer layer (GaN ud 100 nm in MD or GaN ud 90 nm in CD) is substantially 0, especially because Applicants do not specifically claim how close to 0 is “substantially 0”.
Response to Arguments
Applicants' arguments filed May 18, 2026 have been fully considered but they are not persuasive, especially because (a) Applicants did not make any arguments traversing the 35 USC 112(b) rejection of claim 1 including the limitation “not actively doped”, (b) it is still not clear what the phrase “not actively doped” suggests, and (c) depending on the processing conditions of the claimed epitaxial structure, the not-actively-doped first and third buffer layer may be able to contain iron impurities whose concentrations are comparable to, or even larger than, the concentration of iron impurities of the second buffer layer.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Isono et al. (US 2021/0005717)
Sato et al. (US 2017/0133217)
Kato et al. (US 10,186,588)
Sato et al. (US 9,876,101)
Applicants' amendment necessitated the new grounds of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicants are reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua Benitez can be reached at (571) 270-1435. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/JAY C KIM/Primary Examiner, Art Unit 2815
/J. K./Primary Examiner, Art Unit 2815 June 16, 2026
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