Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
Amendment filed on 6/8/26 has been entered.
Response to Arguments
Applicant’s arguments have been fully considered but they are moot because the arguments do not apply to any of the references being used in the current rejection.
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 of this title, 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 and 3-5 are rejected under AIA 35 U.S.C. 103 as being unpatentable over Li (US 20120273795) in view of Khan et al. (US 6764888).
Regarding claim 1. (Currently Amended) Li discloses a semiconductor device comprising a substrate 102, a buffer layer 104 above substrate 102, a back barrier layer 106 on buffer layer 104, a channel layer 108 on back barrier layer 106, and an electron supply layer 112 above channel layer 108 (Fig. 1). Li's channel layer 108 corresponds to the claimed electron traveling layer.
Li discloses that buffer layer 104 is GaN and teaches epitaxially growing GaN buffer layer 104 to a thickness of 6000 nm. Li further discloses that channel layer 108 is non-doped GaN having a thickness of 50 nm, wherein “non-doped” indicates that an impurity causing conduction is not intentionally added. Thus, Li teaches an undoped GaN electron traveling layer and teaches that the electron traveling layer is thinner than the buffer layer because 50 nm < 6000 nm.
Li further teaches that back barrier layer 106 has a greater bandgap energy than GaN channel layer 108. Because Li's buffer layer 104 and channel layer 108 are both GaN, Li thereby teaches that the bandgap of back barrier layer 106 is greater than the bandgap of both GaN buffer layer 104 and GaN electron traveling/channel layer 108.
Li further expressly teaches that back barrier layer 106 may comprise AlInGaN, specifically AloInpGa1-o-pN, while channel layer 108 may comprise GaN.
But Li does not expressly disclose that GaN buffer layer 104 is undoped, or that the AlInGaN embodiment of back barrier layer 106 is undoped and has Al and In mole fractions satisfying 0<x≤1 and 0≤y≤0.1, as claimed.
However, Khan teaches an AlInGaN/GaN heterostructure comprising a 6H-SiC substrate 32, an intrinsic GaN (i-GaN) layer 34, and a quaternary AlInGaN barrier layer 36 on the i-GaN layer (Fig. 4a). Thus, Khan demonstrates the known use of intrinsic, i.e., not intentionally doped, GaN underlying an AlInGaN barrier in an AlInGaN/GaN heterostructure.
Khan further teaches a nominally undoped quaternary AlInGaN barrier layer associated with GaN. Khan also expressly teaches AlxInyGa1-x-yN/GaN junctions having x from 0.1 to 0.2 and y from 0.02 to 0.04 (col 4, line 19-22), which fall within the claimed ranges 0<x≤1 and 0≤y≤0.1.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form Li's GaN buffer layer 104 as intrinsic/undoped GaN, as taught by Khan, and to form Li's expressly contemplated AlInGaN back barrier layer 106 as a nominally undoped AlInGaN layer having Al and In compositions within the ranges taught by Khan.
Li already selects GaN for buffer layer 104 and expressly contemplates AlInGaN for back barrier layer 106. Khan demonstrates the use of intrinsic GaN underlying an AlInGaN barrier in the same AlInGaN/GaN material system and further demonstrates nominally undoped AlInGaN barriers having compositions within the claimed ranges. Thus, the proposed modification applies known doping conditions and known AlInGaN compositions to Li's expressly disclosed materials without changing Li's basic layer arrangement or back-barrier function.
Moreover, Khan teaches that the quaternary AlInGaN material system permits control of strain and band offsets and discusses the effects of composition on lattice mismatch, polarization, and electronic characteristics. A person of ordinary skill therefore would have had reason to employ Khan's known AlInGaN compositions and intrinsic/undoped conditions in Li's structure to obtain predictable control of the physical and electronic characteristics of the AlInGaN/GaN heterostructure, with a reasonable expectation of success. Accordingly, Li in view of Khan renders claim 1 obvious.
Regarding claim 3. (Currently Amended) Li in view of Khan teaches the semiconductor device according to claim 1 for the reasons discussed above.
Li further teaches that back barrier layer 106 may be formed of AlxGa1-xN, wherein 0 < x ≤ 1, while channel layer 108 may be formed of GaN [0021].
Li's AlxGa1-xN composition corresponds to the claimed AlxInyGa1-x-yN composition when y=0, which is expressly permitted by claim 1 (0≤y≤0.1). When y=0, the relationship recited in claim 3, y+0.8≤x, reduces to 0.8≤x.
Li expressly discloses the Al composition range 0<x≤1 for back barrier layer 106. Accordingly, Li's disclosed range overlaps the range satisfying claim 3 over 0.8≤x≤1 when y=0.
Moreover, Li expressly recognizes the Al composition ratio X of back barrier layer 106 as a result-effective variable affecting device performance. In [0043], Li evaluates carrier concentration and threshold voltage Vth as functions of Al composition X and teaches that when Al composition X is low, the effect of increasing Vth is also low. Li further teaches that X is preferably no less than 0.05 and more preferably no less than 0.1.
Thus, Li teaches both a range of Al compositions that encompasses the compositions satisfying claim 3 and that the Al composition X is a parameter affecting the threshold-voltage characteristics of the device. It would therefore have been obvious to one of ordinary skill in the art to optimize the Al composition X within Li's expressly disclosed range to obtain a desired threshold-voltage characteristic. Selection of X within the overlapping portion 0.8≤x≤1, with y=0, would have predictably resulted in a barrier composition satisfying y+0.8≤x. Therefore, Li in view of Khan renders claim 3 obvious.
Regarding claim 4. (Original) Li in view of Khan teaches the semiconductor device according to claim 1 for the reasons discussed above. Claim 4 further requires that a thickness of the barrier layer is 2 nm or larger and 20 nm or smaller.
Khan expressly teaches, with respect to the AlInGaN/GaN heterostructure of Fig. 4a, a quaternary AlInGaN barrier layer 36 formed over i-GaN layer 34. Khan further teaches that, as determined from SEM images, the total thickness of the AlInGaN barrier varied between 15 nm and 17 nm (col 5, line 53-54).
Khan's disclosed barrier thickness of 15–17 nm falls entirely within the claimed range of 2–20 nm.
Accordingly, it would have been obvious to one of ordinary skill in the art to employ Khan's known AlInGaN barrier thickness of 15–17 nm for Li's AlInGaN back barrier layer 106. Li expressly contemplates AlInGaN as the material of back barrier layer 106, and Khan experimentally demonstrates an AlInGaN/GaN heterostructure employing an AlInGaN barrier having the recited thickness. Selection of Khan's known barrier thickness for Li's AlInGaN barrier therefore would have been a predictable implementation of Li's expressly contemplated AlInGaN back-barrier embodiment with a reasonable expectation of success. Therefore, Li in view of Khan renders claim 4 obvious.
Regarding claim 5. (Original) Li in view of Khan teaches the semiconductor device according to claim 1 for the reasons discussed above. Claim 5 further requires that a thickness of the buffer layer is 20 μm or smaller.
Li expressly teaches in [0032] that GaN buffer layer 104 is epitaxially grown to a thickness of 6000 nm.
A thickness of 6000 nm corresponds to:
6000 nm = 6 μm.
Because 6 μm ≤ 20 μm, Li expressly teaches a buffer-layer thickness falling within the claimed range.
Accordingly, Li in view of Khan teaches the additional limitation of claim 5.
Claim 6 is rejected under AIA 35 U.S.C. 103 as being unpatentable over Li (US 20120273795) in view of Khan et al. (US 6764888), and further in view of Chen (US 20220029007).
Regarding claim 6. (Original) Li in view of Khan discloses the semiconductor device according to claim 1 for the reasons discussed above.
But Li in view of Khan does not expressly disclose that the electron traveling layer has a thickness of 200 nm or larger.
However, Chen teaches a semiconductor heterostructure including a back barrier layer 112, channel layer 114, and front barrier layer 116, arranged in sequence [0035]. Chen teaches that the channel layer 114 may be GaN [0057]. Chen further expressly teaches that the thickness of the channel layer 114 is about 200–500 nm [0063]. Accordingly, Chen teaches a GaN channel layer, corresponding to the claimed electron traveling layer, having a thickness of 200 nm or larger.
Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the GaN electron traveling layer of Li to have a thickness within the about 200–500 nm range taught by Chen, because Chen teaches such thicknesses as suitable for a GaN channel layer positioned between barrier layers in a nitride semiconductor heterostructure. The modification would have amounted to selecting a known thickness for a known GaN channel layer used for the same electron-conduction function, with predictable results.
Accordingly, claim 6 is rejected under 35 U.S.C. § 103 as being unpatentable over Li in view of Khan and further in view of Chen.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is 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 extension fee 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 date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Changhyun Yi whose telephone number is (571)270-7799. The examiner can normally be reached Monday-Friday: 10A-3P.
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/Changhyun Yi/Primary Examiner, Art Unit 2812
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