DETAILED ACTION
This Office Action is in response to Application filed May 11, 2023.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
Applicant's election with traverse of Group I, Species A drawn to the embodiment shown in Fig. 5 of current application and Subspecies IV drawn to the embodiment directed to a contact transition layer formed of undoped hafnium nitride layer recited in the previously presented claims 6 and 13 in the reply filed on January 14, 2026 is acknowledged. The traversal is on the grounds that “the Applicant makes the election of Invention I, Species A, and Subspecies IV with traverse because the Examiner has not demonstrated that a serious search and examination burden would be imposed if restriction were not required”, that “Although the Examiner asserts that there is an examination and search burden for these patentably distinct species, the proper standard for properly imposing a restriction requires that there must be a serious burden on the Examiner if a restriction were not required”, that “As relevant here, the Examiner has not demonstrated that a serious burden would exist in searching and examining all present claims concurrently”, that “Of course, searching additional limitations present in claims directed to different species imposes some burden on the Examiner”, that “However, there must be a serious burden on the Examiner in order to properly restrict such species”, and that “In particular, the Applicant believes that searching for art in the elected invention, species, and subspecies will also uncover the most relevant art for the unelected invention, species, and subspecies, and thus a serious search and examination burden does not exist”. This is not found persuasive because (a) a serious burden on the Examiner to perform a search and examination of all the claims directed to distinct Inventions is not the standard of restricting distinct inventions, i.e. method claims and structure/medium claims, and Applicant has already withdrawn claims directed to an unelected invention, (b) Applicant does not provide any evidence that there would not be a serious burden on the Examiner to perform a search and examination of all the claims directed to distinct Inventions, Species and Subspecies, (c) it is not clear what Applicant implies by a serious burden since it appears that Applicant argues that “some burden” can be imposed on the Examiner in one of the arguments cited above, while the some burden is not a serious burden, see the sentence “Of course, searching additional limitations present in claims directed to different species imposes some burden on the Examiner” cited above, (d) therefore, without Applicant’s clarifying the distinction between some burden and a serious burden, Applicant’s arguments cited above are not persuasive, (e) furthermore, Applicant does not provide any evidence that the Species and Subspecies are obvious variants from each other as discussed in the Restriction Requirement mailed November 14, 2025, (f) Applicant does not provide any substantiating evidence for the statement “In particular, the Applicant believes that searching for art in the elected invention, species, and subspecies will also uncover the most relevant art for the unelected invention, species, and subspecies, and thus a serious search and examination burden does not exist”, and (g) it appears that Applicant amended dependent claims to remove distinct features associated with the Species and/or Subspecies restriction. The requirement is still deemed proper and is therefore made FINAL.
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 1-16 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.
(1) Regarding claim 1, it is not clear what “an ohmic contact for a semiconductor structure” recited in the preamble refers to, because (a) Applicant does not claim any semiconductor material layer, not to mention a semiconductor structure, in claim 1 after the amendment to claim 1 made on January 14, 2026, and (b) therefore, it is not clear whether the claimed contact transition layer of hafnium nitride (HfN) is deposited on “a semiconductor structure” to form “an ohmic contact”, or the claimed contact transition layer of hafnium nitride (HfN) is deposited on a certain, but unspecified, intermediate device structure followed by depositing a semiconductor material layer for “a semiconductor structure”.
(2) Further regarding claim 1, it is not clear how “an ohmic contact of a semiconductor structure” recited in the preamble can be formed after the step of “forming a metal layer on the contact transition layer” as recited on line 6, because (a) an ohmic contact is a contact configuration between a semiconductor material and a metal where an interface of the semiconductor material and the metal does not have any energy barrier, (b) therefore, unless the contact transition layer of hafnium nitride (HfN) is a semiconductor material, which does not appear to be the case, “an ohmic contact of a semiconductor structure” recited in the preamble should be formed (i) right after the step of “depositing a contact transition layer of hafnium nitride (HfN)” recited on lines 3-5 directly on “a semiconductor structure”, (ii) after “a semiconductor structure” is formed on “a contact transition layer of hafnium nitride (HfN)”, and then “a metal layer” recited on line 6 is formed directly on “a semiconductor structure”, or (iii) “a semiconductor structure” is formed directly on “a metal layer” recited on line 6, and (c) in other words, one cannot form “the ohmic contact” following the step of “forming a metal layer on the contact transition layer” formed of hafnium nitride (HfN) since “the ohmic contact” should already have been formed before “a metal layer” recited on line 6 is formed or after “a semiconductor structure” is formed on “a metal layer”.
Claims 2-11 depend on claim 1, and therefore, claims 2-11 are also indefinite.
(3) Regarding claim 5, it is not clear what the limitation “the ohmic contact is a p-type contact or n-type contact” recited in claim 5 suggests, because (a) as discussed above with regard to claim 1, Applicant does not claim any semiconductor material layer, not to mention “a semiconductor structure”, in the claim body of claim 1, and (b) therefore, it is not clear whether the p-type or n-type contact refers to a conductivity type of the hafnium nitride (HfN) contact transition layer, or a conductivity type of an unspecified and unclaimed semiconductor material layer constituting “a semiconductor structure”.
(4) Regarding claim 6, it is not clear what the limitation “the ohmic contact is a source or drain” recite in claim 6 suggests, because (a) as discussed above with regard to claim 1, Applicant does not claim any semiconductor material layer, not to mention “a semiconductor structure”, in the claim body of claim 1, and (b) therefore, it is not clear whether the source or drain refers to the hafnium nitride (HfN) contact transition layer, or a portion of an unspecified and unclaimed semiconductor material layer constituting “a semiconductor structure”.
(5) Regarding claim 12, it is not clear how “an ohmic contact of a semiconductor structure” recited in the preamble can be formed after the step of “forming a metal layer on the contact transition layer” as recited on lines 8-9, because (a) an ohmic contact is a contact configuration between a semiconductor material and a metal where an interface of the semiconductor material and the metal does not have any energy barrier, (b) therefore, unless the contact transition layer formed of hafnium nitride (HfN) recited on lines 5-6 is a semiconductor material that can be a source or drain of the semiconductor structure, which does not appear to be the case, “an ohmic contact of a semiconductor structure” recited in the preamble should be formed right after the step of “depositing a contact transition layer” recited on line 5 rather than after the step of “forming a metal layer on the contact transition layer” as recited on lines 8-9, and (c) in this case, it is not clear whether “a metal layer” recited on line 8 should undergo an additional, but unclaimed, process “to form the ohmic contact for a source or drain of the semiconductor structure” such as diffusion of atoms constituting “a metal layer”, or “a contact transition layer” recited on line 5 undergoes an additional, but unclaimed, process such as the contact transition layer dissolving into “a metal layer” during the step of “forming a metal layer on the contact transition layer”. Claims 13-16 depend on claim 12, and therefore, claims 13-16 are also indefinite.
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 1-16, as best understood, are rejected under 35 U.S.C. 103 as being unpatentable over Beach et al. (US 7,649,215) in view of Jorgensen et al. (US 2017/0345642)
Regarding claim 1, Beach et al. disclose a method for forming an ohmic contact (19 in Fig. 1C; “Ohmic Contact”) of a semiconductor structure (semiconductor structure adjacent and below “Ohmic Contact”) (col. 4, lines 33-37), comprising: depositing a contact transition layer (16) of hafnium nitride (HfN) (col. 7, lines 32-33); and forming a metal layer (19) (col. 3, lines 44-45) on the contact transition layer to form the ohmic contact, because (a) an ohmic contact including the “Ohmic Contact” 19 disclosed by Beach et al. is a contact configuration between a semiconductor material layer and a metal layer, (b) therefore, the “Ohmic Contact” 19 disclosed by Beach et al. should be a metal layer, and (c) the limitation “to form the ohmic contact” is indefinite as discussed above under 35 USC 112(b) rejections.
Beach et al. differ from the claimed invention by not showing that the hafnium nitride (HfN) contact transition layer is deposited using a physical vapor deposition (PVD) process.
Jorgensen et al. disclose that a hafnium nitride (HfN) layer as well as a GaN layer can be deposited using a physical vapor deposition (PVD) process ([0125]).
Since both Beach et al. and Jorgensen et al. teach GaN-based semiconductor materials and a HfN material, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the hafnium nitride (HfN) contact transition layer disclosed by Beach et al. can be deposited using a physical vapor deposition (PVD) process as disclosed by Jorgensen et al., because a PVD process including a sputter deposition process has been commonly employed in semiconductor industry to manufacture GaN-based semiconductor materials and other nitride materials including HfN to simplify the manufacturing process and/or to reduce the manufacturing cost.
Regarding claims 2-9, Beach et al. further comprise forming at least one recess (recess inside which HfN layer 16 is deposited in Fig. 1C, which is ohmic contact window 11 in Fig. 1B) on a substrate (10 or not-shown substrate) (col. 10, lines 3-6) prior to depositing the contact transition layer (16); and forming a mask (12 in Fig. 1B) on the substrate, because (a) Applicant does not specifically claim when exactly the mask is formed, and what the mask is formed of, and (b) therefore, when the layer 12, which is a gate insulator layer, is patterned to form the at least one recess, the remainder of the layer 12 would function as a mask, wherein the at least one recess is unmasked prior to depositing the contact transition layer (claim 2), wherein the mask (12 in Fig. 1B) is a photoresist or dielectric, because the layer 12 is a gate insulator layer (col. 7, line 17) (claim 3), and the at least one recess (11) on the substrate (10 or not-shown substrate) is a trench (claim 4), the ohmic contact (19) is a p-type contact or n-type contact, because (a) this limitation is indefinite as discussed above under 35 USC 112(b) rejections, and (b) the ohmic contact 19 is in direct contact with the “Non-Stoichiometric n+GaN” layer in Fig. 1C, and thus can be referred to as an n-type contact (claim 5), the ohmic contact (19) is a source or drain, because this limitation is indefinite as discussed above under 35 USC 112(b) rejections, especially when Applicant does not claim what “a semiconductor structure” refers to (claim 6), the ohmic contact (19) is formed on the semiconductor structure (semiconductor structure in Fig. 1C) on a substrate of sapphire or silicon carbide (col. 10, lines 3-6) (claim 7), further comprising: forming a mask (12 in Fig. 1B) prior to deposition of the contact transition layer (16 in Fig. 1C), wherein the mask remains in place during formation of the metal layer (19), see the explanations on the term “mask” in the prior art rejection of claim 2 (claim 8), wherein a reveal (11 in Fig. 1B; ohmic contact window) is formed adjacent to the mask (12 in Fig. 1B), because (a) Applicant does not specifically claim what the “reveal” refers to, and (b) a top surface of the layer 10 is revealed via the ohmic contact window 11 in Fig. 1B (claim 9).
Regarding claim 10, Beach et al. in view of Jorgensen et al. differ from the claimed invention by not further comprising: depositing the contact transition layer using a remote plasma PVD process.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the method disclosed by Beach et al. in view of Jorgensen et al. can further comprise a step of depositing the contact transition layer using a remote plasma PVD process, because (a) as discussed above with regard to the prior art rejection of claim 1, Jorgensen et al. disclose a PVD process, and (b) a remote plasma PVD process has been one of the PVD processes that have been commonly employed in semiconductor research and industry to improve quality of the deposited material layers, while simplifying the manufacturing process and/or reducing the manufacturing cost.
Regarding claim 11, Beach et al. in view of Jorgensen et al. differ from the claimed invention by not further comprising: depositing the contact transition layer at a temperature of approximately 300 degrees Celsius to approximately 900 degrees Celsius.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the method disclosed by Beach et al. in view of Jorgensen et al. can further comprise a step of depositing the contact transition layer at a temperature of approximately 300 degrees Celsius to approximately 900 degrees Celsius, because (a) as discussed above with regard to the prior art rejection of claim 1, Jorgensen et al. disclose a PVD process, and (b) a deposition temperature for a PVD process should be controlled and optimized to improve quality of the deposited material layers, while simplifying the manufacturing process and/or reducing the manufacturing cost.
Please refer to the explanations of the corresponding limitations above.
Regarding claim 12, Beach et al. disclose a method for forming an ohmic contact (19 in Fig. 1C) of a semiconductor structure, comprising: forming at least one recess (11 in Fig. 1B) in a semiconductor material (Non-Stoichiometric n+GaN in Fig. 1C) of the semiconductor structure; depositing a contact transition layer (16) in the at least one recess, wherein the contact transition layer is hafnium nitride (HfN); and forming a metal layer (19) on the contact transition layer to form the ohmic contact.
Beach et al. differ from the claimed invention by not showing that the hafnium nitride (HfN) contact transition layer is deposited using a physical vapor deposition (PVD) process with a remote plasma source, and the ohmic contact is for a source or drain of the semiconductor structure.
Beach et al. further disclose that “said III-nitride semiconductor device comprises a high electron mobility transistor (HEMT)” in claim 5 of Beach et al., comprising a gate (15 in Fig. 1E) (col. 8, line 9).
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 ohmic contact 19 shown in Fig. 1C of Beach et al. can be an ohmic contact for a source or drain of the semiconductor structure, because an ohmic contact electrode adjacent to a gate in a HEMT device has been commonly an ohmic contact for either a source or a drain to form a functioning HEMT device.
Further regarding claim 12, Beach et al. differ from the claimed invention by not showing that the hafnium nitride (HfN) contact transition layer is deposited using a physical vapor deposition (PVD) process with a remote plasma source.
Jorgensen et al. disclose that a hafnium nitride (HfN) layer as well as a GaN layer can be deposited using a physical vapor deposition (PVD) process ([0125]).
Since both Beach et al. and Jorgensen et al. teach GaN-based semiconductor materials and a HfN material, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the hafnium nitride (HfN) contact transition layer disclosed by Beach et al. can be deposited using a physical vapor deposition (PVD) process as disclosed by Jorgensen et al., because a PVD process including a sputter deposition process has been commonly employed in semiconductor industry to manufacture GaN-based semiconductor materials and other nitride materials including HfN to simplify the manufacturing process and/or to reduce the manufacturing cost.
Still further regarding claim 12, Beach et al. in view of Jorgensen et al. differ from the claimed invention by not showing that the physical vapor deposition (PVD) process is performed with a remote plasma source.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the method disclosed by Beach et al. in view of Jorgensen et al. can further comprise a step of performing the PVD process with a remote plasma source, because (a) Applicant does not specifically claim where the “remote plasma source” is located, what it is constituted of, and what it does, and (b) therefore, the “sputtering” process mentioned in paragraph [0125] of Jorgensen et al., which is one of well-known and commonly employed PVD processes, can be performed by using a remote plasma source to sputter a target material, which is formed of HfN, i.e. there is some distance between the sputter target material and the substrate, to deposit the claimed HfN contact transition layer since a remote plasma source providing energetic ions to sputter away atoms from a target material onto a substrate has been commonly employed in a sputtering process in semiconductor research and industry to improve quality of the deposited material layers, while simplifying the manufacturing process and/or reducing the manufacturing cost.
Regarding claims 13-15, Beach et al. further comprise forming a mask (12 in Fig. 1B) prior to deposition of the contact transition layer (16 in Fig. 1C), wherein the mask remains in place during formation of the metal layer (19 in Fig. 1C) (claim 13), further comprising: forming a mask (12 in Fig. 1B) on the semiconductor structure, wherein the at least one recess (11 in Fig. 1B) is unmasked prior to depositing the contact transition layer (16 in Fig. 1C) (claim 14), wherein the mask (12 in Fig. 1B) is a photoresist or dielectric material (claim 15).
Regarding claim 16, Beach et al. in view of Jorgensen et al. differ from the claimed invention by not further comprising: depositing the contact transition layer at a temperature of approximately 300 degrees Celsius to approximately 900 degrees Celsius.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the method disclosed by Beach et al. in view of Jorgensen et al. can further comprise a step of depositing the contact transition layer at a temperature of approximately 300 degrees Celsius to approximately 900 degrees Celsius, because (a) as discussed above with regard to the prior art rejection of claim 12, Jorgensen et al. disclose a PVD process such as a sputter deposition process, and (b) a deposition temperature for a PVD process should be controlled and optimized to improve quality of the deposited material layers, while simplifying the manufacturing process and/or reducing the manufacturing cost.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Wang et al. (US 11,251,304)
Wu et al. (US 11,276,781)
Tomikawa et al. (US 5,422,500)
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 February 6, 2026