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 Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 3-5, 16, 21 and 22 are rejected under 35 U.S.C. 102(a)(1) or (a)(2) as being anticipated by Wan et al. (US 9,608,075)
Regarding claim 1, Wan et al. disclose a semiconductor device (Figs. 1 and 4) (col. 7, lines 28-33; please note that the Al and Ga contents are substantially constant in and throughout the Low and High Carbon Buffer in Fig. 4) comprising: a substrate (110); a buffer layer (AlGaN layer illustrated below, which corresponds to 102 in Fig. 1) provided above the substrate and consisting essentially of a group III nitride semiconductor (AlGaN), because the limitation “buffer” is directed to an intended use of a layer interposed between the substrate and a layer or layers deposited on the buffer layer;
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an intermediate layer (AlGaN layer illustrated below, which corresponds to composite layer of 104 and 116 in Fig. 1) provided above the buffer layer;
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an electron transport layer (106 in Fig. 1) provided above the intermediate layer and consisting essentially of a group III nitride semiconductor (GaN) (col. 6, line 33); an electron supply layer (108) provided above the electron transport layer and consisting essentially of a group III nitride semiconductor (AlGaN) (col. 6, line 34) inherently having a band gap greater than a band gap of the group III nitride semiconductor in the electron transport layer (106), because an AlGaN has a band gap larger than a GaN due to the presence of the smaller Al atoms in the AlGaN in comparison to larger Ga atoms, resulting in a stronger covalent bonding and a greater band gap; a source electrode (not-shown source contact) (col. 3, lines 40-46) and a drain electrode (not-shown drain contact) provided above the electron supply layer and spaced apart from each other; and a gate electrode (not-shown gate contact to apply gate voltage) (col. 3, line 43) provided above the electron supply layer and spaced apart from each of the source electrode and the drain electrode, which is inherent to form a functioning semiconductor device with the source and drain contacts on the same side, wherein the intermediate layer includes a stack resulting from stacking a first intermediate layer (116, which is also illustrated below and indicated by “first”) and a second intermediate layer (104, which is also illustrated below and indicated by “second” in two illustrations),
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the second intermediate layer is provided above the first intermediate layer, the first intermediate layer (116 in Fig. 1 also illustrated above) consists essentially of a group III nitride semiconductor (AlGaN) inherently having a band gap smaller than a band gap of the group III nitride semiconductor in the buffer layer (102 in Fig. 1 also illustrated above), because (a) as shown in Fig. 4 of Wan et al., the High Carbon Buffer 102 has an Al composition larger than an Al composition in the Low Carbon Buffer 104 and the Medium Carbon Buffer 116, and (b) the transitional phrase “consists essentially of” does not necessarily suggest a completely and perfectly uniform material composition, especially when the carbon concentration profile shown in Fig. 3 of current application are not uniform in the first and second intermediate layer, the second intermediate layer ((portion of) 104 in Fig. 1 also illustrated above) consists essentially of a group III nitride semiconductor (AlGaN) inherently having a band gap smaller than the band gap of the group III nitride semiconductor in the buffer layer, because as shown in Fig. 4 of Wan et al., the High Carbon Buffer 102 has an Al composition larger than an Al composition in the Low Carbon Buffer 104 and the Medium Carbon Buffer 116, the band gap of the group III nitride semiconductor (GaN) in the electron transport layer (106) is inherently smaller than the band gap of the group III nitride semiconductor in the first intermediate layer (AlGaN) and smaller than the band gap of the group III nitride semiconductor in the second intermediate layer (AlGaN) for the same reason stated above, a carbon concentration of the second intermediate layer ((portion of) 104 in Fig. 1 also illustrated above) is lower than a carbon concentration of the first intermediate layer (116 in Fig. 1 also illustrated above), and the carbon concentration of the first intermediate layer is lower than a carbon concentration of the buffer layer (102 in Fig. 1 also illustrated above), and is in a range from 2E+16 atoms/cm³ to 7E+16 atoms/cm³, because (a) the y axis of Fig. 4 of Wan et al. is in a logarithmic scale, and therefore, the region between the two horizontal lines illustrated below indicates a range from 2E+16 atoms/cm³ to 7E+16 atoms/cm³, (b) some locations of the first intermediate layer have the claimed carbon concentration as shown in Fig. 4,
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and (c) as can be seen in Fig. 3 of current application, which is illustrated below, some locations of the first intermediate layer, but not the entirety of the first intermediate layer, have the claimed carbon concentration, see for example the two arrows corresponding to the locations where the carbon concentration is outside of the claimed range.
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Regarding claim 3, Wan et al. further disclose that a thickness of the first intermediate layer (104 in Fig. 1 also illustrated above) is at least 600 nm, see also the illustration below.
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Regarding claim 4, Wan et al. further disclose that a thickness of the second intermediate layer (bottom portion of 104 in Fig. 1 also illustrated above) is at most 400 nm, see also the illustration below, because (a) Applicants do not specifically claim that the claimed intermediate layer consists of the first intermediate layer and the second intermediate layer, (b) Applicants do not specifically claim that the second intermediate layer is in direct contact with the electron transport layer, (c) the second intermediate layer illustrated below is slightly different than an upper portion of the Low Carbon Buffer in that it is in direct contact with the first intermediate layer and its carbon concentration appears to be slightly less than the carbon concentration of the upper portion of the Low Carbon Buffer, and (d) therefore, the second intermediate layer having a thickness smaller than 400 nm illustrated below can be referred to as the claimed second intermediate layer without Applicants further claiming the characteristics or properties of the claimed second intermediate layer.
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Regarding claims 5 and 16, Wan et al. further disclose for the semiconductor device according to claims 1 and 3 that an average Al composition percentage of the first intermediate layer (116 in Fig. 1 also illustrated above) is higher than or equal to an average Al composition percentage of the second intermediate layer (104 in Fig. 1 also illustrated above), see the illustrations above, and an average Al composition percentage of the buffer layer (High Carbon Buffer 102 in Fig. 1 also illustrated above) is higher than the average Al composition percentage of the first intermediate layer, see the illustrations above.
Regarding claim 21, Wan et al. further disclose for the semiconductor device according to claim 1 that the carbon concentration of the second intermediate layer (104 in Fig. 1) is in a range from 1.0E+15 atoms/cm³ to 2E+16 atoms/cm³, see the illustrations above.
Regarding claim 22, Wan et al. further disclose for the semiconductor device according to claim 1 that the carbon concentration of the buffer layer (102 in Fig. 1) is in a range from 1.0E+19 atoms/cm³ to 3E+20 atoms/cm³, see the illustration below.
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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 6, 7, 18, 20 and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Wan et al. (US 9,608,075) The teachings of Wan et al. are discussed above.
Regarding claims 6, 7, 18 and 20, Wan et al. differ from the claimed invention by not showing that an average Al composition percentage of the first intermediate layer is at least 5% and at most 10% (claims 6 and 18), and a difference between an average Al composition percentage of the second intermediate layer and an average Al composition percentage of the first intermediate layer is at most 5% (claims 7 and 20).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that an average Al composition percentage of the first intermediate layer can be at least 5% and at most 10%, and a difference between an average Al composition percentage of the second intermediate layer and an average Al composition percentage of the first intermediate layer can be at most 5%, because (a) these limitations are associated with the material compositions of the first and second intermediate layer, which thus should be controlled and optimized to improve the quality of, and to reduce the defects in, the electron transport layer deposited on the first and second intermediate layer, which would improve performance of the claimed semiconductor device, and (b) the claims are prima facie obvious without showing that the claimed ranges of the average Al compositions and their difference achieve 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 23, Wan et al. differ from the claimed invention by not showing that a thickness of the intermediate layer is at least 1000 nm and at most 1395 nm.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that a thickness of the intermediate layer can be at least 1000 nm and at most 1395 nm, because (a) the thickness of the intermediate layer should be controlled and optimized in view of the overall device thickness and the epitaxial growth process that would determine the quality of the electron transport layer, and (b) the claim is prima facie obvious without showing that the claimed range of the thickness of the intermediate 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).
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.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Zhang et al. (US 12,482,653)
Briere (US 8,796,738)
Nakamura et al. (US 2013/0248872)
Chen et al. (US 2020/0075314)
Mohanta et al. (US 12,356,651)
Sato et al. (US 2017/0133217)
Sato et al. (US 10,833,184)
Sato et al. (US 2017/0033209)
Ichimura et al. (US 10,410,859)
Huang et al., “The Characteristics of 6-Inch GaN on Si RF HEMT with High Isolation Composited Buffer Layer Design,” Electronics 10 (2021) 46.
Malmros et al., “Impact of Channel Thickness on the Large Signal Performance in InAlGaN/AlN/GaN HEMTs With an AlGaN Back Barrier,” IEEE TRANSACTIONS ON ELECTRON DEVICES 66 (2019) pp. 364-371.
Gamarra et al., “Optimisation of a carbon doped buffer layer for AlGaN/GaN HEMT devices,” Journal of Crystal Growth 414 (2015) pp. 232-236.
Bergsten et al., “Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results,” APPLIED PHYSICS LETTERS 107 (2015) 262105.
Gustafsson et al., “Dispersive Effects in Microwave AlGaN/AlN/GaN HEMTs With Carbon-Doped Buffer,” IEEE TRANSACTIONS ON ELECTRON DEVICES 62 (2015) pp. 2162-2169.
Luong et al., “Performance Improvements of AlGaN/GaN HEMTs by Strain Modification and Unintentional Carbon Incorporation,” Electronics Materials Letters 11 (2015), pp. 217-224.
Vohra et al., “Epitaxial buffer structures grown on 200mm engineering substrates for 1200 V E-mode HEMT application,” Applied Physics Letters 120 (2022) 261902.
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 11, 2026
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