3DETAILED ACTION
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 .
Response to Arguments
Regarding claim 1, Applicant argues Zeimer in view of Hirayama does not create a random micro-grooved template by pulsed epitaxy.
However, such a limitation is not recited by claim 1. Claim 1 recites “forming a rough AlN layer upon the substrate by pulsed epitaxy, the rough AlN layer acting as a random micro-grooved template having facets”. Zeimer teaches formation of a rough AlN layer having random micro-grooves and facets via epitaxy and Hirayama teaches forming a rough AlN layer via pulsed epitaxy. Additionally, the Examiner notes the language “acting as a random micro-grooved template having facets” is indefinite since it is unclear whether the rough AlN layer has random-microgrooves and facets. See below.
Applicant further argues Zeimer in view of Hirayama does not teach the claimed 16-25 micron crack-free AlN layer.
However, neither Zeimer nor Hirayama are relied upon for teaching the 16-25 micron crack-free AlN layer. Kamikawa teaches a 16-25 micron AlN layer. See below.
Applicant further argues Kamikawa expressly stops growth short of coalescence since, as recited in Kamikawa, “if the ELO III-nitride layers coalesce with each other, it causes fluctuations in the surface roughness. Furthermore, the region of coalescence causes many stacking faults and misfit dislocations.”
However, while Kamikawa does expressly stop growth short of coalescence, the reasons cited above are not exclusively why. The invention of Kamikawa relies on the ELO III-nitride not coalescing for subsequent fabrication steps which are not relevant in view of previously cited reference Zeimer. Zeimer explicitly shows coalescence of AlN epilayers. See below.
Regarding claims 4 and 14, Applicant applies arguments similar to those applied to claim 1. See above.
Regarding claim 8, Applicant argues claim 8 requires, in sequence, bonding the wafer to a temporary carrier, performing laser liftoff, forming a backside n-contact on the N-polar face, bonding that contact to a metallic preform, removing the temporary carrier, and only then fabricating the vertical conduction device on the side of the wafer opposite the n-contact. An argues Zhou performs these operations in a materially different order.
However, the examiner notes that an order of claimed method steps does not necessarily require the exact order claimed without intervening steps since it has been held in Altiris Inc. v. Symantec Corp., 318 F.3d 1363, 1371, 65 USPQ2d 1865, 1869-70 (Fed. Cir. 2003) (Although the specification discussed only a single embodiment, the court held that it was improper to read a specific order of steps into method claims where, as a matter of logic or grammar, the language of the method claims did not impose a specific order on the performance of the method steps, and the specification did not directly or implicitly require a particular order), MPEP 2111.01. Thus, the rejection of claim 8 stands. See below.
Regarding claim 9, Applicant argues Khan2 alone or in combination does not teach reverse grading in the region of a backside n-contact on the N-polar face of a wafer.
However, Khan2 does teach this limitation. The Examiner notes the term “region” has been interpreted under broadest reasonable interpretation (BRI, MPEP § 2111.01) as defining an arbitrary region.
Regarding claim 10, Applicant argues Imanishi teaches a different substrate and a different polarity regime. Specifically, Imanishi teaches a buffer grown on a conductive SiC for a GaN-base HEMT. Thus, Applicant argues, an AlN buffer on conductive SiC is not an N-polar AlN substrate produced by wafer bonding and excimer laser liftoff.
However, the test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). Thus, the rejection of claim 10 stands. See below.
Regarding claims 12 and 13, Applicant argues Sung’s Ti/Ni stack serves an unrelated function as a reflector capping layer and thin-film diffusion barrier.
However, in the device taught by Zeimer in view of Hirayama, Kamikawa, and Pinnington, Sung’s Ti/Ni stack serves the purpose of protecting the reflective layer of Pinnington and/or protecting underlying semiconductor layer and providing a current-spreading layer (¶ [0077] of Sung).
Applicant further argues the wetting layer of Pinnington comprises Ti/Pt/Au does not teach the claimed Ti/Au wetting layer of the instant application since it includes Pt.
However, the Ti/Pt/Au layer of Pinnington includes Ti/Au.
Applicant further argues Zhou does not supply the claimed heat sink sequence.
However, the examiner notes that an order of claimed method steps does not necessarily require the exact order claimed without intervening steps since it has been held in Altiris Inc. v. Symantec Corp., 318 F.3d 1363, 1371, 65 USPQ2d 1865, 1869-70 (Fed. Cir. 2003) (Although the specification discussed only a single embodiment, the court held that it was improper to read a specific order of steps into method claims where, as a matter of logic or grammar, the language of the method claims did not impose a specific order on the performance of the method steps, and the specification did not directly or implicitly require a particular order), MPEP 2111.01. Thus, the rejection of claims 12-13 stands. See below.
Claim Objections
Claims 1 and 4 are objected to because of the following informalities:
The limitation “to lead to lateral epitaxy” of claim 1 should read “ing to lateral epitaxy”.
The limitation “1-3 x 108 cm-2” of claim 4 should read “1-3 x 108 cm-2”.
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 1-2 and 4-14 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.
Claim 1 recites inter alia “the rough AlN layer acting as a random micro-grooved template having facets” which is indefinite since 1) it is unclear how “the rough AlN layer” is structurally distinguished from other rough AlN layers disclosed in prior art due to the underlined functional language above and 2) it is unclear if the rough AlN layer has random micro-grooves and facets or the rough AlN layer has other structural characteristics which are equivalent to the presence of random micro-grooves and facets.
Additionally, claim 1 recites inter alia “forming air-pockets that relieve the strain” which is indefinite since 1) it is unclear what the strain is relieved relative to and 2) it has been held that a vice of functional claiming occurs "when the inventor is painstaking when he recites what has already been seen, and then uses conveniently functional language at the exact point of novelty", MPEP 2173.05(g) wherein in the instant case it is unclear whether the mere presence of air pockets is sufficient to relieve strain or what additional structure is required, if any, to achieve the claimed function.
Claims 2 and 4-14 are rejected under 35 U.S.C. 112(b) insofar as they depend upon and recite all the limitations of claim 1 as claimed.
Claim 4 recites “as confirmed by etch-pit density measurement” which is indefinite since it is unclear whether etch-pit density measurement is performed in the claimed method.
Claim 5 recites “the ultrawide band gap AlxGa1-xN template serving as a quasi-bulk AlxGa1-xN substrate” which is indefinite since it is unclear how “the ultrawide band gap AlxGa1-xN template” is structurally distinguished from other ultrawide band gap AlxGa1-xN templates disclosed in prior art due to the underlined functional language above
Claim 9 recites “from AlGaN to GaN, disposed in the region of the at least one backside n-contact on the N-polar face of the at least one wafer such that electron accumulation occurs at the at least one backside n-contact” which is indefinite since it is unclear how “the at least one backside n-contact” is structurally distinguished from other backside n-contacts in the prior art die to the underlined functional language above.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1 and 5-6 are rejected under 35 U.S.C. 103 as being unpatentable over Zeimer et al. (U. Zeimer, V. Kueller, A. Knauer, A. Mogilatenko, M. Weyers, M. Kneissl, High quality AlGaN grown on ELO AlN/sapphire templates, Journal of Crystal Growth, Volume 377, 2013, Pages 32-36, ISSN 0022-0248; hereinafter Zeimer) in view of Hirayama et al. (US 20090057646 A1; hereinafter Hirayama), and further in view of Kamikawa et al. (US 20210013365 A1; hereinafter Kamikawa).
Regarding claim 1, FIGS. 1(b), 2(d), 3(a) of Zeimer teach a method for growing crack free AIN layers comprising: providing a substrate comprising sapphire (c-plane sapphire substrate § 2. Experimental ¶ 1 – “c-plane sapphire substrate”) forming a rough AlN layer (AlN layer shown in FIG. 1(b) after etching) upon the substrate via epitaxy (“500 nm thick AlN layers were grown by MOVPE” § 2. Experimental ¶ 1), the rough AlN layer acting as a random micro-grooved template having facets; modifying the growth conditions after formation of the random micro-grooved template to lead to lateral epitaxy from the sidewalls of the rough layer facets (§ 2. Experimental ¶ 1 “the templates were overgrown with AlN… until coalescence”); and coalescing the laterally grown AlN and forming air-pockets (gaps shown in coalesced AlN in FIG. 3(a)) that relieve the strain.
Regarding the language “acting as a random micro-grooved template having facets”, the Examiner notes this language constitutes functional language and while features of an apparatus may be recited either structurally or functionally, claims directed to an apparatus must be distinguished from the prior art in terms of structure rather than function. In re Schreiber, 128 F.3d 1473, 1477-78, 44 USPQ2d 1429, 1431-32 (Fed. Cir. 1997). As best can be determined by the Examiner from the specification of the present application, the structure which performs the function “acting as a random micro-grooved template having facets” is simply the formation of the rough AlN layer, a structure which is clearly present in the device of Zeimer. Therefore, it appears the structure of Zeimer can perform the function required by the claim language.
Regarding the claim language “coalescing the laterally grown AlN and forming air-pockets that relieve the strain”, the Examiner notes the underlined language constitutes functional language and while features of an apparatus may be recited either structurally or functionally, claims directed to an apparatus must be distinguished from the prior art in terms of structure rather than function. In re Schreiber, 128 F.3d 1473, 1477-78, 44 USPQ2d 1429, 1431-32 (Fed. Cir. 1997). As best can be determined by the Examiner from the specification of the present application, the structure which performs the function “that relieve the strain” is simply the existence of air-pockets. Therefore, it appears the structure of Zeimer can perform the function required by the claim language.
Zeimer does not teach forming the rough AlN layer upon the substrate by pulsed epitaxy.
FIGS. 1A-6 of Hirayama teach a method for growing crack free AlN layers (15 ¶ [0053]) comprising: providing a substrate (1) comprising sapphire (¶ [0046]) and configured for pulsed epitaxial growth (¶ [0006][0048] ‘pulsed supply growth’) of a random-microgrooved AlN template (e.g. 3); forming at least one AlN layer (3, 5, 7, 11, 15) upon the substrate via a pulsed epitaxial growth process ((A) ¶ [0006],[0048] ‘pulsed supply growth’) in which precursor supply (NH3) is temporally modulated (see FIG. 3 ¶ [0050]-[0051]) to form the random-microgrooved template (3, see FIG. 1B (A)) such that the AlN layer (3) is configured as a random-microgrooved template (3, see FIG. 1B (A)) having non-periodic microgrooves (micro-grooves shown in FIG. 1B (A)) distributed across the AlN growth surface (sapphire substrate 1) rather than a lithographically defined periodic ridge-and-trench pattern (¶ [0048]); and modifying growth conditions (e.g. conditions shown in FIG. 2) by changing epitaxial deposition parameters (3 grown at high temperature and pressure, 5 grown at low temperature and pressure ¶ [0049]) after formation of the random-microgrooved template (3) to form lateral epitaxy ((B) ‘pulsed supply enhanced lateral growth’) from at least one sidewall of the at least one AlN layer (3, see FIG. 1B (B) ¶ [0048]) to form coalesced layers of the at least one AlN layer (5) and substrate (1 ¶ [0048]).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack-free AlN layers taught by Zeimer with the method for growing crack-free AlN layers taught by Hirayama for the purpose of suppressing edge dislocations, improving flatness, and forming a crack-free AlN layer (¶ [0053]).
Zeimer does not teach the crack-free AlN layer having a thickness of 16-25 µm.
Kamikawa teaches a method of fabricating a semiconductor device comprising growing at least one III-nitride layer (105 ¶ [0074]) configured as a random-microgrooved template; wherein the at least one III-nitride layer (105) is grown through lateral epitaxial overgrowth (¶ [0014]) and epitaxy ceases prior to adjacent III-nitride layers (105) coalescing (¶ [0020],[0079]); and wherein the at least one AlN layer random-microgrooved template (105) is 20 µm thick (¶ [0187]).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of growing III-nitride layers taught by Kamikawa since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955), In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969), wherein in the instant case the thickness of the AlN layer determines the resulting device dimensions making it a result effective variable, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), and MPEP 2144.05 Obviousness of Ranges II. OPTIMIZATION OF RANGES A. Optimization Within Prior Art Conditions or Through Routine Experimentation B. Only Result-Effective Variables Can Be Optimized.
Regarding claim 5, Zeimer as modified teaches the method of claim 1 and FIG. 3(a) of Zeimer further teaches further comprising, forming an ultrawide band gap AlxGa1-xN template (Al0.5Ga0.5N layer grown on AlN) over the coalesced crack-free AlN layers containing the air-pockets by air-pocket assisted pulsed lateral epitaxy (gaps shown in coalesced AlN in FIG. 3(a)), the ultrawide band gap AlxGa1-xN template (Al0.5Ga0.5N layer grown on AlN) serving as a quasi-bulk AlxGa1-xN substrate.
Regarding the language “ultrawide band gap AlxGa1-xN template serving as a quasi-bulk AlxGa1-xN substrate”, the Examiner notes the underlined language constitutes functional language and while features of an apparatus may be recited either structurally or functionally, claims directed to an apparatus must be distinguished from the prior art in terms of structure rather than function. In re Schreiber, 128 F.3d 1473, 1477-78, 44 USPQ2d 1429, 1431-32 (Fed. Cir. 1997). As best can be determined by the Examiner from the specification of the present application, the structure which performs the function “serving as a quasi-bulk AlxGa1-xN substrate” is simply the ultrawide band gap AlxGa1-xN template, a structure which is clearly present in the device of Zeimer as modified. Therefore, it appears the structure of Zeimer as modified can perform the function required by the claim language.
Regarding claim 6, Zeimer as modified teaches the method of claim 1.
Zeimer as modified does not teach wherein the at least one AlN layer random-microgrooved template is 16-25 µm thick.
Kamikawa teaches a method of fabricating a semiconductor device comprising growing at least one III-nitride layer (105 ¶ [0074]) configured as a random-microgrooved template; wherein the at least one III-nitride layer (105) is grown through lateral epitaxial overgrowth (¶ [0014]) and epitaxy ceases prior to adjacent III-nitride layers (105) coalescing (¶ [0020],[0079]); and wherein the at least one AlN layer random-microgrooved template (105) is 20 µm thick (¶ [0187]).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of growing III-nitride layers taught by Kamikawa since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955), In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969), wherein in the instant case the thickness of the AlN layer determines the resulting device dimensions making it a result effective variable, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), and MPEP 2144.05 Obviousness of Ranges II. OPTIMIZATION OF RANGES A. Optimization Within Prior Art Conditions or Through Routine Experimentation B. Only Result-Effective Variables Can Be Optimized.
Claim 2 are rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama and Kamikawa, and further in view of Ariyuki (US 20170260650 A1; hereinafter Ariyuki).
Regarding claim 2, Zeimer as modified teaches the method of claim 1.
Kamikawa as modified does not teach wherein the coalesced crack-free AIN layer has an RMS surface roughness of 0.11 nm.
Ariyuki teaches a method for fabricating an AlN layer and subsequently processing to achieve an ultra-flat surface (¶ [0043]-[0045]), wherein the AlN layer has a RMS surface roughness of 0.11 nm (¶ [0045]).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method taught by Zeimer with the processing steps taught by Ariyuki for the purpose of effectively removing minute impurities (abstract) and achieving an ultra-flat surface (¶ [0043]).
Claim 4 are rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama and Kamikawa, and further in view of Cardwell et al. (US 20210246571 A1; hereinafter Cardwell).
Regarding claim 4, Zeimer as modified teaches the method of claim 1, and Zeimer further teaches wherein the at least one AlN layer (ELO AlN) has a screw defect density of value of 5.5 x 107 cm-2 and an edge defect density of 8.2 x 108 cm-2 (Table 1 – 0.25° to m miscut) after lateral epitaxial coalescence of the random-microgrooved template (see FIG. 3(a)).
Zeimer as modified does not teach wherein the coalesced crack-free AlN layer has a defect density value of substantially 1-3 x 108 cm-2 after lateral epitaxial coalescence of the random micro-grooved template.
FIGS. 1A-T, 3A-3E, 4A-C of Cardwell teach a method for growing crack free AlN layers (e.g. FIGS. 1A-T, 3A-3E) comprising: providing a substrate (101 ¶ [0079]); forming at least one AlN layer (213 ¶ [0010]-[0011],[0111]) upon the substrate (101) via epitaxy (¶ [0033], [0112]) such that the AlN layers (213) is configured as a random-microgrooved (223) template (see FIG. 3C ¶ [0112]); modifying growth conditions to form lateral epitaxy (continued lateral epitaxial growth of 213) from at least one sidewall of the at least one AlN layer (sidewall(s) of 213 ¶ [0113]); and wherein the at least one AlN layer (213) has a defect density value of substantially 1-3 x 108 cm-2 (¶ [0117]).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of for growing crack free AlN layers taught by Zeimer with the method for growing crack free AlN layers taught by Cardwell for the purpose of lowering the defect density of the AlN layers (¶ [0117]) and since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955), In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969), wherein in the instant case the defect density of AlN layers determines the resulting growth conditions and electric properties making it a result effective variable, In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977), and MPEP 2144.05 Obviousness of Ranges II. OPTIMIZATION OF RANGES A. Optimization Within Prior Art Conditions or Through Routine Experimentation B. Only Result-Effective Variables Can Be Optimized.
Regarding the language “as confirmed by etch-pit density measurement”, the Examiner notes it is unclear whether an “etch-pit density measurement” process is performed as part of the claimed method of manufacturing. Therefore, it appears the structure of Zeimer in view of Hirayama, Kamikawa, and Cardwell teaches the claimed structure with a defect density value of substantially 1-3 x 108 cm-2 after lateral epitaxial coalescence of the random micro-grooved template and this could be confirmed using an etch-pit density measurement.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama and Kamikawa, and further in view of Zhou et al. (L. Zhou, J. E. Epler, M. R. Krames, W. Goetz, M. Gherasimova, Z. Ren, J. Han, M. Kneissl, N. M. Johnson; Vertical injection thin-film AlGaN/AlGaN multiple-quantum-well deep ultraviolet light-emitting diodes. Appl. Phys. Lett. 11 December 2006; 89 (24): 241113; hereinafter Zhou).
Regarding claim 8, Zeimer teaches the method of claim 1, and FIG. 3(a) of Zeimer further teaches further comprising, forming an ultrawide band gap substrate (Al0.5Ga0.5N layer grown on AlN) from the coalesced crack-free AlN layers (AlN in FIG. 3(a)) produced by claim 1.
Zeimer does not teach further comprising, fabricating at least one vertically conducting UWBG AlxGa1-xN device via: growing at least one epilayer over an ultrawide band gap AlxGa1-xN substrate to form at least one wafer; bonding the at least one wafer to a temporary carrier; performing laser liftoff of the at least one wafer; forming at least one backside n-contact on a N-polar face of the at least one wafer; bonding the at least one backside n-contact to at least one metallic preform; removing the temporary carrier; and fabricating at least one vertical conduction device on a side of the at least one wafer opposite the n-contact, wherein the ultrawide band gap substrate is formed from the crack-free AlN layers produced by claim 1.
FIGS. 1(a)-(b), para. 4/line 17-22, and para. 5/lines 1-16 of Zhou teach fabricating at least one vertically conducting UWBG AlxGa1-xN device (FIGS. 1(a)-(b)) via: growing at least one epilayer (MQW layer, p-AlGaN layer, p-GaN layer) over an ultrawide band gap AlxGa1-xN substrate (n-AlGaN layer) to form at least one wafer (n-AlGaN layer, MQW layer, p-AlGaN layer, and p-GaN layer); bonding the at least one wafer (n-AlGaN layer, MQW layer, p-AlGaN layer, and p-GaN layer) to a temporary carrier ("metal-coated carrier wafer"); performing laser liftoff ("laser-assisted liftoff") of the at least one wafer (n-AlGaN layer, MQW layer, p-AlGaN layer, and p-GaN layer); forming at least one backside n-contact on a N-polar face of the at least one wafer (“exposing the nitrogen-terminated n-type AlxGa1-xN contact layer”); bonding the at least one backside n-contact (nitrogen-terminated n-type AlxGa1-xN contact layer) to at least one metallic preform (cathode grid/n-type contact); removing the temporary carrier ("devices are singulated, mounted to a heat sink, and wire bonded"); and fabricating at least one vertical conduction device (p-contact/reflector, formed prior to laser liftoff) on a side of the at least one wafer opposite the n-contact (cathode grid/n-type contact, see FIG. 1(b)).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of fabricating at least one vertically conducting UWBG AlxGa1-xN device taught by Zhou for the purpose of enhancing the functionality of the UWBG AlxGa1-xN device taught by Zhou by providing large reductions in the concentrations of dislocations in III-nitride layers (§ 3.1 ¶ 3, Table 1 of Zeimer) since it has been held in KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 415-421, 82 USPQ2d 1385, 1395-97 (2007), MPEP 2143(I)(A), that examples of rationales that may support a conclusion of obviousness include combining prior art elements according to known methods to yield predictable results, wherein in the instant case the method of fabricating at least one UWBG AlxGa1-xN device is taught in the art, one having ordinary skill in the art could have combined the method of fabricating at least one UWBG AlxGa1-xN device with Zeimer with each element performing the same function as it does separately, and one having ordinary skill in the art would have found the combination predictable since the components are commonly used together.
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama, Kamikawa, and Zhou, and further in view of Khan et al. (US 20110012089 A1; hereinafter Khan2).
Regarding claim 9, Zeimer as modified teaches the method of claim 8, and Zhou further teaches at least one backside n-contact on a N-polar face of the at least one wafer (“exposing the nitrogen-terminated n-type AlxGa1-xN contact layer”; FIGS. 1(a)-(b), para. 4/line 17-22, and para. 5/lines 1-16).
Zeimer as modified does not teach further comprising reverse grading, from AlGaN to GaN, disposed in the region of the at least one backside n-contact.
FIG. 5 of Kahn2 teaches a light-emitting device including a buffer layer (404 ¶ [0064]) comprising reverse grading, from AlGaN to GaN, disposed in the region of (e.g. region of light emitting structure shown in FIG. 5) at least one backside n-contact (401 ¶ [0022],[0063]).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the UV light-emitting device taught by Khan2 for the purpose of controlling thin-film stress and mitigating epilayer cracking (¶ [0010]).
Regarding the language “such that electron accumulation occurs at the at least one backside n-contact”, the Examiner notes this language constitutes functional language and while features of an apparatus may be recited either structurally or functionally, claims directed to an apparatus must be distinguished from the prior art in terms of structure rather than function. In re Schreiber, 128 F.3d 1473, 1477-78, 44 USPQ2d 1429, 1431-32 (Fed. Cir. 1997). As best can be determined by the Examiner from the specification of the present application, the structure which performs the function “electron accumulation occurs at the at least one backside n-contact” is simply the backside n-contact on the N-polar face of the at least one wafer, a structure which is clearly present in the device of Zeimer as modified. Therefore, it appears the structure of Zeimer as modified can perform the function required by the claim language.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama and Kamikawa, and further in view of Gu et al. (US 20170133295 A1; hereinafter Gu), Cardwell, and Imanishi et al. (US 20080197359 A1; hereinafter Imanishi).
Regarding claim 10, Zeimer as modified teaches the method of claim 1.
Zeimer as modified does not teach further comprising, wafer bonding and excimer laser liftoff to form an N-polar AlN substrate for growth of a high-electron-mobility transistor.
FIGS. 1A-2 of Gu teach a method of fabricating a semiconductor structure comprising: providing a substrate (16 ¶ [0024]); forming at least one AlN layer (22 ¶ [0024]-[0025]) upon the substrate (16); wafer bonding (e.g. wafer bonding 26 to 22 ¶ [0025]-[0026]); removing the substrate (16 ¶ [0026]) to form an N-polar GaN substrate (surface BS2 of buffer 20 ¶ [0025],[0030]) for growth of a high-electron mobility transistor (FIG. 5G, note presence of 2DEG).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of manufacturing a III-nitride semiconductor device taught by Gu for the purpose of enhancing the functionality of the III-nitride semiconductor device taught by Gu by providing large reductions in the concentrations of dislocations in III-nitride layers (§ 3.1 ¶ 3, Table 1 of Zeimer) since it has been held in KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 415-421, 82 USPQ2d 1385, 1395-97 (2007), MPEP 2143(I)(A), that examples of rationales that may support a conclusion of obviousness include combining prior art elements according to known methods to yield predictable results, wherein in the instant case the method of fabricating a III-nitride semiconductor device is taught in the art, one having ordinary skill in the art could have combined the method of fabricating a III-nitride semiconductor device with Zeimer with each element performing the same function as it does separately, and one having ordinary skill in the art would have found the combination predictable since the components are commonly used together.
Zeimer as modified does not teach further comprising, conducting laser lift-off of the at least one AlN layer.
FIGS. 1A-T, 3A-3E, 4A-C of Cardwell teach a method for growing crack free AlN layers (e.g. FIGS. 1A-T, 3A-3E) comprising: providing a substrate (101 ¶ [0079]); forming at least one AlN layer (213 ¶ [0010]-[0011],[0111]) upon the substrate (101) via epitaxy (¶ [0033], [0112]) such that the AlN layers (213) is configured as a random-microgrooved (223) template (see FIG. 3C ¶ [0112]); modifying growth conditions to form lateral epitaxy (continued lateral epitaxial growth of 213) from at least one sidewall of the at least one AlN layer (sidewall(s) of 213 ¶ [0113]); and conducting laser lift-off of the at least one AlN layer (213 ¶ [0119]).
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of for growing crack free AlN layers taught by Zeimer with the method for growing and lifting-off crack free AlN layers taught by Cardwell for the purpose of increasing throughput.
Zeimer as modified does not teach an N-polar AlN substrate.
Imanishi teaches a HEMT device (e.g. FIG. 2) comprising an AlN buffer layer (102 ¶ [0031]).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the AlN buffer layer taught by Imanishi since it has been held that the selection of a known material based on its suitability for its intended use supported a prima facie obviousness determination in Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945), In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960), and MPEP 2144.07 Art Recognized Suitability for an Intended Purpose.
Claims 12-13 are rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Hirayama and Kamikawa, and further in view of Pinnington et al. (US 7732301 B1; hereinafter Pinnington), Sung et al. (US 20190259910 A1; hereinafter Sung), and Zhou.
Regarding claim 12, Zeimer as modified teaches the method of claim 1, and FIG. 3(a) of Zeimer further teaches at least one AlN layer formed as the crack-free coalesced layer (region where AlN coalesces shown in FIG. 3(a)) containing at least one air pocket (gaps shown in coalesced AlN in FIG. 3(a)).
Zeimer as modified does not teach further comprising, forming a heat sink via: introducing at least one submount plate to the at least one AlN layer; depositing a Ti/Ni/Ti/Ni/Ti/Ni buffer layer; depositing a Ti/Au wetting layer; depositing AuSn solder followed by soldering; and performing substrate liftoff.
FIGS. 2A-2N of Pinnington teach a method of fabricating a III-nitride semiconductor structure including forming a heat sink (50, 51 col. 41/lines 55-63) via: introducing at least one submount plate (50) to the at least one AlN layer (at least one of 30, see FIG. 2M); depositing a Ti/Au wetting layer (“the adhesion layer is provided prior to the provision of the eutectic bonding layer… comprising Ti/Pt/Au,” not shown, col. 42/lines 21-28); depositing AuSn solder (51) followed by soldering (“eutectic bonding,” i.e. eutectic soldering); and removing the substrate (20, see FIG. 2N).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of fabricating a III-nitride semiconductor structure taught by Pinnington for the purpose of enhancing the functionality of the III-nitride semiconductor structure taught by Pinnington by providing large reductions in the concentrations of dislocations in III-nitride layers (§ 3.1 ¶ 3, Table 1 of Zeimer) since it has been held in KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 415-421, 82 USPQ2d 1385, 1395-97 (2007), MPEP 2143(I)(A), that examples of rationales that may support a conclusion of obviousness include combining prior art elements according to known methods to yield predictable results, wherein in the instant case the III-nitride semiconductor structure is taught in the art, one having ordinary skill in the art could have combined the method of fabricating the III-nitride semiconductor structure with Zeimer with each element performing the same function as it does separately, and one having ordinary skill in the art would have found the combination predictable since the components are commonly used together.
Zeimer as modified does not teach depositing a Ti/Ni/Ti/Ni/Ti/Ni buffer layer.
FIG. 1 of Sung teaches a light-emitting semiconductor device including a Ti/Ni/Ti/Ni/Ti/Ni buffer layer (140) disposed on a reflective layer (132 ¶ [0077],[0101]).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the buffer layer taught by Sung for the purpose of protecting the reflective layer of Pinnington and/or protecting underlying semiconductor layers and providing a current-spreading layer (¶ [0077]).
Zeimer as modified does not teach performing substrate liftoff.
FIGS. 1(a)-(b), para. 4/line 17-22, and para. 5/lines 1-16 of Zhou teach a method of fabricating a light-emitting device including forming metallic contacts and a carrier wafer on a sapphire/GaN substrate and removing the sapphire/GaN substrate by laser-assisted lift-off.
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the laser-assisted lift-off method taught by Zhou for the purpose of mitigating cracking and decreasing fluences necessary to achieve lift-off (para. 4/lines 9-17).
Regarding claim 13, Zeimer as modified teaches the method of claim 12, and FIG. 1 of Sung further teaches a light-emitting semiconductor device including a Ti/Ni/Ti/Ni/Ti/Ni buffer layer (140) disposed on a reflective layer (132 ¶ [0077],[0101]).
FIGS. 2A-2N of Pinnington further teach wherein the submount plate is Cu or CuW (col. 41/lines 38-42) and is introduced to the at least one AlN layer (at least one of 30, see FIG. 2M) after formation of a reflective layer (40, see FIGS. 2J-2N col. 36/lines 40-42).
FIGS. 1(b), 2(d), 3(a) of Zeimer further teach the crack-free coalesced AlN layer containing the air-pockets (gaps shown in coalesced AlN in FIG. 3(a)).
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Zeimer in view of Zhou and Kamikawa, and further in view of Kim et al. (US 20130069079 A1; hereinafter Kim).
Regarding claim 14, Zeimer teaches the method of claim 5, and FIG. 3(a) of Zeimer further teaches at least one AlN layer formed as the crack-free coalesced layer (region where AlN coalesces shown in FIG. 3(a)).
Zeimer does not teach further comprising introducing at least one GaN layer and at least one low temperature AlN layer between the AlxGa1-xN template and the substrate.
FIGS. 1(a)-(b), para. 4/line 17-22, and para. 5/lines 1-16 of Zhou further teach further comprising, introducing at least one GaN layer (GaN layer) and at least one low temperature AlN layer (LT-AlN layer) between the AlxGa1-xN template (n-AlGaN layer, p-AlGaN layer) and the substrate (sapphire substrate, see FIG. 1(a)).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method for growing an AlGaN layer on a sapphire substrate for the purpose of preventing cracking during AlGaN growth (¶ 4 “A GaN template layer is grown first and then followed with a low-temperature metamorphic AlN interlayer to prevent cracking during AlGaN growth…”).
Zeimer as modified does not teach introducing at least one AlN spacer.
FIGS. 1A-E of Kim teach a method of fabricating epitaxial AlN layers (3, 4) on a sapphire substrate (2); wherein the epitaxial AlN layers (3, 4) comprise at least one AlN layer configured as a random-microgrooved template (3) and at least one AlN spacer (4) formed directly above the at least one AlN layer (3).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method for growing crack free AlN layers taught by Zeimer with the method of fabricating AlN layers on a sapphire substrate taught by Kim for the purpose of significantly reducing threading dislocation density while preventing decreases in throughput and increases in manufacturing cost (¶ [0004]-[0006]).
Allowable Subject Matter
Claims 7 and 11 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Claim 7 recites the method of claim 1 further comprising, conducting excimer laser lift-off of the coalesced crack-free AlN layer from the substrate after high-temperature wafer bonding, to form an N-polar AlN substrate.
Zeimer in view of Hirayama and Kamikawa teach the method of claim 1.
FIGS. 1A-T, 3A-3E, 4A-C of Cardwell teach a method for growing crack free AlN layers (e.g. FIGS. 1A-T, 3A-3E) comprising: providing a substrate (101 ¶ [0079]); forming at least one AlN layer (213 ¶ [0010]-[0011],[0111]) upon the substrate (101) via epitaxy (¶ [0033], [0112]) such that the AlN layers (213) is configured as a random-microgrooved (223) template (see FIG. 3C ¶ [0112]); modifying growth conditions to form lateral epitaxy (continued lateral epitaxial growth of 213) from at least one sidewall of the at least one AlN layer (sidewall(s) of 213 ¶ [0113]); and conducting laser lift-off of the at least one AlN layer (213 ¶ [0119]).
However, the prior art fails to teach or reasonably suggest “lift-off of the coalesced crack-free AlN layer from the substrate after high-temperature wafer bonding” together with all the limitations of claims 1 and 7 as claimed.
Claim 11 recites The method of claim 1 further comprising, removing the substrate and replacing the substrate with a high-thermal conductivity metal preform after formation of the coalesced crack-free AIN layers containing the air-pockets, wherein the high-thermal conductivity metal preform is bonded to a backside metal contact on an N-polar face of the coalesced crack-free AlN layers.
Zeimer in view of Hirayama and Kamikawa teach the method of claim 1.
FIG. 3(a) of Zeimer teaches formation of coalesced crack-free AlN layers (region where AlN coalesces shown in FIG. 3(a)) containing the at least one air pocket (gaps shown in coalesced AlN in FIG. 3(a) in region where AlN coalesces).
FIGS. 1A-1F of Gu teach a method of fabricating a semiconductor structure comprising: providing a substrate (16 ¶ [0024]); forming at least one AlN layer (18, 22 ¶ [0024]-[0025]) upon the substrate (16); removing the substrate (16) and replacing the substrate (16) with a high-thermal conductivity metal preform (24, FIGS. 1E-1F show steps where 24 has replaced 16 ¶ [0026]).
However, the prior art fails to teach or reasonably suggest “wherein the high-thermal conductivity metal preform is bonded to a backside metal contact on an N-polar face of the coalesced crack-free AlN layers” together with all the limitations of claims 1 and 11 as claimed.
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 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 Nora T Nix whose telephone number is (571)270-1972. The examiner can normally be reached Monday - Friday 9:00 am - 5:00 pm ET.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Matthew Landau can be reached at (571) 272-1731. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/Nora T. Nix/Assistant Examiner, Art Unit 2891
/MATTHEW C LANDAU/Supervisory Patent Examiner, Art Unit 2891
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