DETAILED ACTION
This Office Action is in response to RCE filed February 13, 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 31 is objected to because of the following informalities: there are two new claims 31. Appropriate correction is required.
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 1-4, 6-9, 17, 19, 21-23, 25, 28, 29 and 31 are rejected under 35 U.S.C. 103 as being unpatentable over Chen (CN 111129009) in view of Hikita et al. (US 8,441,035)
Regarding claim 1, Chen discloses a device (Fig. 3O), comprising: a gallium nitride (GaN) layer (330) on a substrate (310); a first aluminum gallium nitride (AIGaN) layer (340) on the GaN layer; a gate structure (structure including MG1 or MG2); and source and drain regions (S and D) in (electrical) contact with the first AIGaN layer, wherein top surfaces of the gate structure and the source and drain regions are coplanar, see Fig. 3I or 3K.
Chen differs from the claimed invention by not comprising a second aluminum gallium nitride (AIGaN) layer having different compositions from the first AlGaN layer, and the source and drain regions are in contact with the second AIGaN layer.
Hikita et al. disclose a device (Fig. 1), comprising: a gallium nitride (GaN) layer (103) (col. 5, lines 33-34); first and second aluminum gallium nitride (AlGaN) layers (104 and 106, respectively) (col. 5, lines 34-37) on the GaN layer having different compositions from one another.
Since both Chen and Hikita et al. teach a device, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the device disclosed by Chen can be modified to comprise the first and second aluminum gallium nitride (AlGaN) layers as disclosed by Hikita et al. instead of a single aluminum gallium nitride (AlGaN) layer as disclosed by Chen, because (a) Applicants do not specifically claim that the first and second AlGaN layers are in contact with each other, and (b) the two aluminum gallium nitride (AlGaN) layers disclosed by Hikita et al. would allow one of ordinary skill in the art to better control strain applied to the channel layer, which would allow one of ordinary skill in the art to better control and optimize the two dimensional electron gas density in the channel layer to improve performance of the claimed device. In this case, the source and drain regions would be in contact with the AIGaN layer in Chen in view of Hikita et al. In addition, please note that the combined device of Chen in view of Hikita et al. would look like the illustration below, where the added horizontal lines would correspond to the top surface of the undoped AlGaN layer 106 of Hikita et al. or the claimed second AlGaN layer with the undoped GaN layer 105 of Hikita et al. not shown in the illustration.
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Regarding claims 2 and 4, Hikita et al. further disclose that an aluminum concentration of the second AlGaN layer (106; 25%) is greater than an aluminum concentration of the first AIGaN layer (104; 15%) (claim 2), wherein the aluminum concentration of the first AlGaN layer (104; 15%) is in the range of about 15% to about 20% (claim 4).
Regarding claim 3, Chen in view of Hikita et al. differ from the claimed invention b not showing that the aluminum concentration of the second AlGaN layer is in the range of about 40% to about 50%.
It would have been obvious to one of ordinary before the effective filing date of the claimed invention that the aluminum concentration of the second AlGaN layer can be in the range of about 40% to about 50%, because (a) the aluminum concentration of the second AlGaN layer can be in the claimed range since the aluminum concentration of the second AlGaN layer would determine the strain applied to the channel layer, which would in turn control the two dimensional electron gas density in the channel layer, (b) in addition, the aluminum concentration of the second AlGaN layer would also determine the passivation characteristics and the overall dielectric constant of the first and second AlGaN layer, which thus should further be controlled and optimized to improve device performance, and (c) the claim is prima facie obvious without showing that the claimed range of the aluminum concentration of the second AlGaN 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 6, Chen in view of Hikita et al. further disclose for the device of claim 1 that the first AIGaN layer (104 of Hikita et al.) extends under the gate structure (structure including MG1 or MG2 of Chen) and the second AlGaN layer (106 of Hikita et al.) does not extend under the gate structure, because (a) Applicants do not specifically claim what the phrase “does not extend under” implies, (b) therefore, the phrase “does not extend under” should be interpreted as “does not extend entirely and directly under”, and (c) as shown in the illustration above, the shorter lines indicating the top surface of the second AlGaN layer do not extend directly under the gate structure including the MG1 or MG2.
Regarding claims 7 and 8, Chen further discloses for the device of claim 1 that the gate structure (structure including MG1 or MG2) comprises a positively-doped GaN (pGaN) layer (claim 7), wherein the gate structure (structure including MG1 or MG2 and pGaN) comprises a T shaped metal gate (MG1 or MG2, or metal gate 1 or metal gate 2) on the pGaN layer, and wherein top surfaces of the T-shaped metal gate and the source and drain regions (S and D) are coplanar (claim 8).
Regarding claim 9, Chen in view of Hikita et al. differ from the claimed invention by not showing that the pGaN layer is doped with magnesium.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the pGaN layer can be doped with magnesium, because magnesium is one of the most, if not the most, commonly employed dopant for doping a gate layer or gate region formed of GaN or AlGaN p-type to form a Schottky barrier between a gate electrode/contact and an underlying device structure formed of GaN-based semiconductor materials.
Regarding claim 28, Chen in view of Hikita et al. differ from the claimed invention by not showing that the T-shaped metal gate comprises a barrier metal layer, an interface layer, and a bulk metal.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the T-shaped metal gate can comprise a barrier metal layer, an interface layer, and a bulk metal, because (a) a plurality of metal and metallic layers have been commonly employed to form a metal gate including TiN or TaN employed as a barrier metal layer since the composite metal and metallic layers would improve adhesion between semiconductor materials and the metal gate, while improving ohmic contact between the semiconductor materials and the metal gate, and (b) it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use, In re Leshin, 125 USPQ 416.
Regarding claim 31, Chen in view of Hikita et al. further discloses for the structure of claim 1 that a first horizontal interface between the first AIGaN layer (340 of Chen, which corresponds to 104 of Hikita et al.) and the source and drain regions (S and D of Chen) is below a second horizontal interface between the second AlGaN layer (106 of Hikita et al.) and the source and drain regions, because (a) Applicants do not claim that the first and second horizontal interfaces are formed by the planar contact areas of the first/second AlGaN layer and the source/drain regions, and (b) therefore, the bottommost borderline between the first AlGaN layer of Chen and Hikita et al. and the source and drain regions S/D of Chen can be referred to as the first horizontal interface, and the topmost borderline between the second AlGaN layer of Hikita et al. and the source and drain regions S/D of Chen can be referred to as the second horizontal interface, see the illustration above.
Please refer to the explanations of the corresponding limitations above.
Regarding claim 17, Chen discloses a structure (Fig. 3O), comprising: a channel layer (330) comprising gallium nitride (GaN); a first aluminum gallium nitride (AIGaN) layer (340) on the channel layer; a first gate structure (pGaN) over the channel layer, the first gate structure comprising positively doped GaN (pGaN); a second gate structure (MG1 or MG2) over the first gate structure, the second gate structure comprising a metal; and a source / drain ohmic layer (S/D) having a first horizontal interface with the first AlGaN layer, see the prior art rejection of claim 31 above.
Chen differs from the claimed invention by not comprising a second aluminum gallium nitride (AIGaN) layer, wherein the source / drain ohmic layer have a second horizontal interface with the second AlGaN layer.
Hikita et al. disclose a structure (Fig. 1), comprising: a gallium nitride (GaN) layer (103); first and second aluminum gallium nitride (AlGaN) layers (104 and 106, respectively).
Since both Chen and Hikita et al. teach a device, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the structure disclosed by Chen can be modified to comprise the first and second aluminum gallium nitride (AlGaN) layers as disclosed by Hikita et al. instead of a single aluminum gallium nitride (AlGaN) layer as disclosed by Chen, because (a) Applicants do not specifically claim that the first and second AlGaN layers are in contact with each other, and (b) the two aluminum gallium nitride (AlGaN) layers disclosed by Hikita et al. would allow one of ordinary skill in the art to better control strain applied to the channel layer, which would allow one of ordinary skill in the art to control and optimize the two dimensional electron gas density in the channel layer to improve performance of the claimed structure. In this case, the source / drain ohmic layer 381/191 of Chen would have a second horizontal interface with the second AlGaN layer for the same reasons stated for the prior art rejection of claim 31 above.
Regarding claim 19, Chen in view of Hikita et al. differ from the claimed invention by not showing that the first AIGaN layer has a thickness between about 150 Å and about 300 Å.
Hikita et al. further disclose that the first AlGaN layer (104) is 10 nm thick.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the first AIGaN layer can have a thickness between about 150 Å and about 300 Å, because (a) Applicants do not specifically claim how close to 150 Å it should be to be referred to be “about 150 Å”, and how close to 300 Å it should be to be referred to be “300 Å”, (b) therefore, the 10 nm thickness for the undoped AlGaN layer 104 of Hikita et al. may be referred to be “about 150 Å”, (c) in addition, the thickness of the first AlGaN layer can be in the claimed range since the thickness of the first AlGaN layer would determine the strain applied to the channel layer, which would in turn control the two dimensional electron gas density in the channel layer, (d) in addition, the thickness of the first AlGaN layer would also determine the passivation characteristics and the overall dielectric constant of the first and second AlGaN layer, which thus should be controlled and optimized to improve device performance, and (e) the claim is prima facie obvious without showing that the claimed range of the thickness of the first AlGaN 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 21, Hikita et al. further disclose for the structure of claim 17 that the first AlGaN layer (104) is between the channel layer (103) and the second AlGaN layer (106), and wherein a first aluminum concentration of the first AlGaN layer is less than a second aluminum concentration of the second AlGaN layer.
Regarding claim 22, Hikita et al. further disclose for the structure of claim 21 that the first aluminum concentration (15% of undoped AlGaN layer 104) is in the range of about 15% to about 20%.
Chen in view of Hikita et al. differ from the claimed invention by not showing that the second aluminum concentration is about 40% to about 50%.
It would have been obvious to one of ordinary before the effective filing date of the claimed invention that the second aluminum concentration of the second AlGaN layer can be in the range of about 40% to about 50%, because (a) the aluminum concentration of the second AlGaN layer can be in the claimed range since the aluminum concentration of the second AlGaN layer would determine the strain applied to the channel layer, which would in turn control the two dimensional electron gas density in the channel layer, (b) in addition, the aluminum concentration of the second AlGaN layer would also determine the passivation characteristics and the overall dielectric constant of the first and second AlGaN layer, which thus should be controlled and optimized to improve device performance, and (c) the claim is prima facie obvious without showing that the claimed range of the aluminum concentration of the second AlGaN 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 29, Chen in view of Hikita et al. further disclose for the structure of claim 17 that the first horizontal interface is between the second horizontal interface and a third horizontal interface between the first AlGaN layer (340 of Chen, which corresponds to 104 of Hikita et al.) and the channel layer (330 of Chen, which corresponds to 103 of Hikita et al.), see the prior art rejection of claim 31 above.
Regarding claims 23 and 31, Chen discloses a structure (Fig. 3O), comprising: a channel layer (330) on a substrate (310) and comprising gallium nitride (GaN); a first aluminum gallium nitride (AlGaN) layer (340) on the channel layer; a gate structure (structure including MG1 or MG2, and pGaN) on the first AlGaN layer; and a source/drain (S/D) region (S/D) in (electrical) contact with the first AlGaN layer, wherein the S/D region has a T-shape (claim 23), wherein the gate structure comprise a T-shaped metal gate (MG1 or MG2), and wherein top surfaces of the T-shaped metal gate and the S/D region are coplanar (claim 31).
Chen differs from the claimed invetnion by not comprising a second AlGaN layer on the first AlGaN layer, wherein an aluminum concentration of the first AlGaN layer is less than an aluminum concentration of the second AlGaN layer, the gate structure is embedded in the second AlGaN layer, and the source/drain (S/D) region is through the second AlGaN layer.
Hikita et al. disclose a device (Fig. 1), comprising: a gallium nitride (GaN) layer (103); first and second aluminum gallium nitride (AlGaN) layers (104 and 106, respectively) on the GaN layer, wherein an aluminum concentration of the first AlGaN layer is less than an aluminum concentration of the second AlGaN layer.
Since both Chen and Hikita et al. teach a structure, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the structure disclosed by Chen can be modified to comprise the first and second aluminum gallium nitride (AlGaN) layers as disclosed by Hikita et al. instead of a single aluminum gallium nitride (AlGaN) layer as disclosed by Chen, because (a) Applicants do not specifically claim that the first and second AlGaN layers are in contact with each other, and (b) the two aluminum gallium nitride (AlGaN) layers disclosed by Hikita et al. would allow one of ordinary skill in the art to better control strain applied to the channel layer, which would allow one of ordinary skill in the art to control and optimize the two dimensional electron gas density in the channel layer to improve performance of the claimed device. In this case, the gate structure disclosed by Chen would be embedded in the second AlGaN layer, and the source/ drain region would be through the second AIGaN layer in Chen in view of Hikita et al., see the illustration above.
Regarding claim 25, Chen in view of Hikita et al. differ from the claimed invention by not showing that a doping concentration of the gate structure is about 1 × 1018 cm-3 to about 1 x 1019 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 a doping concentration of the gate structure can be about 1 × 1018 cm-3 to about 1 x 1019 cm-3, because the doping concentration of the gate structure should be controlled to optimize the barrier height associated with the gate structure, which would in turn control and optimize the device characteristics such as a threshold voltage.
Allowable Subject Matter
Claims 26 and 27 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Response to Arguments
Applicants’ arguments with respect to claims 1 and 23 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.
Bothe et al. (US 2023/0261054)
LaRoche et al. (US 11,476,154)
Chu (US 10,692,984)
Kuraguchi et al. (US 2013/0248873)
Dasgupta et al. (US 11,552,075)
Mishra et al. (US 8,519,438)
Lee et al. (US 2014/0253241)
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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/JAY C KIM/Primary Examiner, Art Unit 2815
/J. K./Primary Examiner, Art Unit 2815 June 22, 2026
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