DETAILED 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 .
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 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 1-18 are rejected under 35 U.S.C. 103 as being unpatentable over Hill (US Publication 20240105808) in view of Wu et al (US Publication 20250311340).
Regarding claim 1, Hill teaches a superlattice buffer structure comprising:
a plurality of superlattice blocks (Fig. 1, 106, para 46 buffer 106 could be multiple crystal layers),
wherein each of the plurality of superlattice blocks has a structure in which a first layer including Al(1-x)GaxN (0≤x≤1) and
a second layer including Al(1-y)GayN (0≤y≤1, x>y) are alternately stacked on each other (Fig. 1, 106, para 45-46),
Hill does not specifically teach the plurality of superlattice blocks are configured to have different average gallium compositions from one another.
Wu teaches the plurality of superlattice blocks are configured to have different average gallium compositions from one another (Fig. 1B, para 33).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Hill to include the plurality of superlattice blocks are configured to have different average gallium compositions from one another as taught by Wu in order to improve the operability and reliability of the device.
Regarding claim 2, Hill as modified teaches the limitations of claim 1 upon which claim 2 depends.
Hill teaches wherein each of the plurality of superlattice blocks independently comprises a dopant of at least one of carbon, iron, and magnesium (para 46, iron, carbon).
Regarding claims 3 and 4, Hill as modified teaches the limitations of claim 1 upon which claim 3 depends.
Hill does not specifically teach:
[claim 3] wherein the average gallium composition is (x×Tx+y×Ty)/(Tx+Ty),
wherein Tx denotes a total thickness sum of a first layer in a corresponding superlattice block, and Ty denotes a total thickness sum of a second layer in the corresponding superlattice block.
[claim 4] wherein the average gallium composition of a superlattice block increases in a stack direction of the first layer and the second layer.
Wu teaches:
[claim 3] wherein the average gallium composition is (x×Tx+y×Ty)/(Tx+Ty),
wherein Tx denotes a total thickness sum of a first layer in a corresponding superlattice block, and Ty denotes a total thickness sum of a second layer in the corresponding superlattice block (Fig. 1B, para 33).
[claim 4] wherein the average gallium composition of a superlattice block increases in a stack direction of the first layer and the second layer (Fig. 1B, para 33).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Hill to include the average gallium composition in the supper lattice buffer layer structure as taught by Wu in order to improve the strain management, crystal quality, and buffer growth of the device.
Regarding claim 5, Hill as modified teaches the limitations of claim 2 upon which claim 5 depends.
Hill teaches wherein a doping concentration of each of the plurality of superlattice blocks increases in a stack direction of the first layer and the second layer (para 46).
Regarding claim 6, Hill as modified teaches the limitations of claim 1 upon which claim 6 depends.
Hill teaches wherein a difference in the average gallium composition between neighboring superlattice blocks of the plurality of superlattice blocks is about 0.01 or more (para 46).
Regarding claim 7, Hill as modified teaches the limitations of claim 2 upon which claim 7 depends.
Hill teaches wherein a doping concentration of each of the plurality of superlattice blocks is in a range of about 1E17 atoms/cm3 to about 1E21 atoms/cm3 (para 46).
Regarding claim 8, as modified Hill teaches the limitations of claim 1 upon which claim 8 depends.
Hill teaches wherein the average gallium composition is in a range of about 0.25 to about 0.95 (para 46).
Regarding claim 9, Hill teaches a semiconductor device comprising:
a substrate (Fig. 1, 104);
a superlattice buffer structure on the substrate (Fig. 1, 106, para 46 buffer 106 could be multiple crystal layers); and
an active layer on the superlattice buffer structure, wherein the superlattice buffer structure comprises a plurality of superlattice blocks,
each of the plurality of superlattice blocks has a structure in which a first layer including Al(1-x)GaxN (0≤x≤1) and
a second layer including Al(1-y)GayN (0≤y≤1, x>y) are alternately stacked on each other (Fig. 1, 106, para 45-46)
Hill does not specifically teach the plurality of superlattice blocks are configured to have different average gallium compositions from one another.
Wu teaches the plurality of superlattice blocks are configured to have different average gallium compositions from one another (Fig. 1B, para 33).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Hill to include the plurality of superlattice blocks are configured to have different average gallium compositions from one another as taught by Wu in order to improve the operability and reliability of the device.
Regarding claim 10, Hill as modified teaches the limitations of claim 9 upon which claim 10 depends.
Hill teaches wherein each of the plurality of superlattice blocks independently comprises a dopant of at least one of carbon, iron, and magnesium (para 46, iron, carbon).
Regarding claims 11 and 12, Hill as modified teaches the limitations of claim 9 upon which claim 11 depends.
Hill does not specifically teach:
[claim 11] wherein the average gallium composition is (x×Tx+y×Ty)/(Tx+Ty),
wherein Tx denotes a total thickness sum of a first layer in a corresponding superlattice block, and Ty denotes a total thickness sum of a second layer in the corresponding superlattice block.
[claim 12] wherein the average gallium composition of a superlattice block increases in a stack direction of the first layer and the second layer.
Wu teaches:
[claim 11] wherein the average gallium composition is (x×Tx+y×Ty)/(Tx+Ty),
wherein Tx denotes a total thickness sum of a first layer in a corresponding superlattice block, and Ty denotes a total thickness sum of a second layer in the corresponding superlattice block (Fig. 1B, para 33).
[claim 12] wherein the average gallium composition of a superlattice block increases in a stack direction of the first layer and the second layer (Fig. 1B, para 33).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the present application for Hill to include the average gallium composition in the supper lattice buffer layer structure as taught by Wu in order to improve the strain management, crystal quality, and buffer growth of the device.
Regarding claim 13, Hill as modified teaches the limitations of claim 10 upon which claim 13 depends.
Hill teaches wherein a doping concentration of each of the plurality of superlattice blocks increases in a stack direction of the first layer and the second layer (para 46).
Regarding claim 14, Hill as modified teaches the limitations of claim 9 upon which claim 14 depends.
Hill teaches wherein a difference in the average gallium composition between neighboring superlattice blocks of the plurality of superlattice blocks is about 0.01 or more (para 46).
Regarding claim 15, Hill as modified teaches the limitations of claim 10 upon which claim 15 depends.
Hill teaches wherein a doping concentration of each of the plurality of superlattice blocks is in a range of about 1E17 atoms/cm3 to about 1E21 atoms/cm3 (para 46).
Regarding claim 16, Hill as modified teaches the limitations of claim 9 upon which claim 16 depends.
Hill teaches wherein the average gallium composition is in a range of about 0.25 to about 0.95 (para 46).
Regarding claim 17, Hill as modified teaches the limitations of claim 9 upon which claim 17 depends.
Hill teaches further comprising: a nucleation layer between the substrate and the superlattice buffer structure (para 46).
Regarding claim 18, Hill as modified teaches the limitations of claim 9 upon which claim 18 depends.
Hill teaches a channel supply layer provided on the active layer and configured to generate a 2-dimensional electron gas in the active layer (Fig. 1, 112, para 48),
wherein a source electrode and a drain electrode are arranged on the active layer to be apart from each other (Fig. 1, 120 and 140 on 150, para 36), and a gate electrode is arranged on the channel supply layer (Fig. 1, 130 on 112).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Yue et al (US Publication 20190198623) – Semiconductor devices with doped regions functioning as enhanced resistivity regions or diffusion barriers, and methods of fabrication therefor
Gupta et al (US Publication 20220157981) – N-polar devices including a depleting layer with improved conductivity
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/NICHOLAS LELAND HUTSON/ Examiner, Art Unit 2818
/JEFF W NATALINI/ Supervisory Patent Examiner, Art Unit 2818