DETAILED ACTION
Notice of Pre-AIA or AIA Status
1. 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
2. Applicant’s arguments, see Pgs. 7-9, filed August 7, 2026, with respect to the rejections of claims 1- under 35 USC § 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Islam et al (US 2022/0130996 A1) in view of Alfieri et al (US 2021/0242021 A1) and Alfieri et al (US 2024/0240357 A1).
Applicant's arguments filed with respect to rejections of claims 18-20 under 35 USC § 103 have been fully considered and are not persuasive. Prior art (Islam et al (US 2022/0130996 A1)) teaches Applicant’s amendment (“wherein the SiC substrate is an n+ layer”) to claim 18 (see below).
3. Regarding the drawing objections, Applicant has amended the drawing to designate the dosimeter as reference character “254”. Examiner withdraws the claim objections due to Applicant’s amendments.
4. Regarding the claim objections, Applicant has amended the informality in claim 14 and the clarity of claim 20. Examiner withdraws the claim objections due to Applicant’s amendments.
Information Disclosure Statement
5. The information disclosure statement (IDS) submitted on February 12, 2025 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner except as otherwise indicated.
Claim Objections
6. Claim 9 objected to because of the following informalities: typo. The phrase “first epitaxial layer is a n+ layer” should read “first epitaxial layer is a n- layer” based on interpretation of original claim as change was not underlined.
Claim 9 will be examined with the phrase changed back to its original language of “first epitaxial layer is a n- layer”.
Appropriate correction is required.
Claim Rejections - 35 USC § 103
7. 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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
8. Claims 1-5 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Islam et al (US 2022/0130996 A1, hereafter Islam) in view of Alfieri et al (US 2021/0242021 A1, hereafter Alfieri 021) and Alfieri et al (US 2024/0240357 A1, hereafter Alfieri 357).
Regarding claim 1, Islam discloses a method, comprising:
providing a silicon carbide (SiC) substrate (Fig. 2A 110; [0097]), wherein the SiC substrate (110) is a n+ layer ([0097]);
forming a first epitaxial layer (Fig. 2A 120; [0098]) over an upper surface of the SiC substrate (110); and
forming a second epitaxial layer (Fig. 2A 130; [0099]) over the first epitaxial layer (120).
Islam fails to disclose passivating the SiC substrate using an ion implant or a plasma doping process.
Alfieri 021 discloses passivating the SiC substrate (Fig. 1B 1; [0071]) using an ion implant (Fig. 1B; [0021], [0022]) or a plasma doping process (Fig. 2; [0021], [0022]) (Specification of instant application discloses that both processes are capable of passivation). Alfieri 021 is analogous to Islam in the field of semiconductor doping.
Alfieri 021 fails to disclose passivating the SiC substrate, wherein the SiC substrate is an n+ layer.
Alfieri 357 discloses passivating ([0012], [0041]) the SiC substrate (Fig. 1 11; [0041]), wherein the SiC substrate (11) is an n+ layer ([0016]). Alfieri 357 is analogous to Islam and Alfieri 021 in the field of semiconductor doping.
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to, prior to epitaxially growing the first and second layer, include the step of treating the SiC substrate using the doping processes disclosed by Alfieri 021 to dope the SiC substrate of Islam prior to epitaxially growing the first and second layer to alter the electrical conductivity of the substrate for device functionality.
Additionally, it would be obvious to perform the ion implant or plasma doping processes on an n+ SiC substrate/layer, as disclosed by Alfieri 357, for the desired device performance.
Regarding claim 2, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 1, further comprising treating the first epitaxial layer (120) using a second ion implant (Islam Fig. 2B 171; [0100]).
Regarding claim 3, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 1, wherein when the SiC substrate (110) is treated using the ion implant (Alfieri 021 [0021], [0022]), the ion implant (Alfieri 021 Fig. 1B; [0021], [0022]) comprises delivering hydrogen ions (Alfieri 021 [0024], [0025]) into the upper surface of the SiC substrate (110).
Regarding claim 4, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 3, wherein the hydrogen ions (Alfieri 021 [0024], [0025]) are delivered while the substrate (110) is at room temperature (between 15 - 40°C) (Alfieri 021 [0080]).
While Alfieri 021 does not explicitly disclose the claimed temperature range, applicant’s specification states room temperature to be 15 - 40°C (see specification paragraph [0022]).
Regarding claim 5, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 3, wherein the hydrogen ions (Alfieri 021 [0024], [0025]) are delivered while the substrate (110) is at a temperature greater than 40°C (Alfieri 021 [0080]).
Regarding claim 10, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 1, wherein the second epitaxial layer (130) is formed prior to formation of a device structure (Fig. 2F; [0108]).
9. Claims 6-8 are rejected under 35 U.S.C. 103 as being unpatentable over Islam, Alfieri 021, and Alfieri 357 as applied to claim 1 above, and further in view of Li et al (US 2022/0262619 A1, hereafter Li).
Regarding claim 6, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 1, wherein when the SiC substrate (110) is treated using the plasma doping process (Alfieri [0021], [0022]), the plasma doping process (Alfieri 021 Fig. 2; [0021], [0022]) comprises treating the SiC substrate (110).
Islam and Alfieri 021 fail to disclose the plasma doping process comprising of providing hydrogen radicals or deuterium radicals into the upper surface of the SiC substrate.
Li discloses a plasma doping process ([0037]) comprising of providing hydrogen plasma ([0038]) into the upper surface ([0036]) of a SiC substrate (0021], [0025]). Li is analogous to Islam and Alfieri 021 in the field of semiconductor doping.
While Li does not explicitly disclose hydrogen radicals, it is known in the art that plasma can form radicals, as evidenced by Bhosle et al (US 2022/0028693 A1, herafter Bhosle) ([0009]), and thus the hydrogen plasma would form hydrogen radicals.
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to substitute the plasma of Islam and Alfieri 021 with the hydrogen plasma of Li in the plasma doping process to yield a predictable result of a passivated SiC substrate with reduced defect density and dangling bonds.
Regarding claim 7, Islam, Alfieri 021, Alfieri 357, and Li disclose the method of claim 6, wherein the hydrogen radicals (Li [0038]) are provided while the substrate (110) is at room temperature (between 15 - 40°C) (Alfieri 021 [0080]).
While Alfieri 021 does not explicitly disclose the claimed temperature range, applicant’s specification states room temperature to be 15 - 40°C (see specification paragraph [0022]).
Regarding claim 8, Islam, Alfieri 021, Alfieri 357, and Li disclose the method of claim 6, wherein the hydrogen radicals (Li [0038]) are provided at a temperature greater than 40°C (Alfieri 021 [080]).
10. Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Islam, Alfieri 021, and Alfieri 357 as applied to claim 1 above, and further in view of Ren et al (US 2021/0098579 A1, hereafter Ren).
Regarding claim 9, Islam, Alfieri 021, and Alfieri 357 disclose the method of claim 1 wherein the first epitaxial layer (120) is a n- layer (Islam [0098]), and wherein the second epitaxial layer (130) is a p layer (Islam [0099]).
Islam, Alfieri 021, and Alfieri 357 fail to explicitly disclose the second epitaxial layer (130) being a p+ layer. However, Islam discloses a range of doping concentration (Islam [0099]) for the p layer, wherein the concentration is 1×1016 to 1×1019 atoms/cm3 (Islam [0099]).
Ren discloses forming a second epitaxial layer ([0034]) that is a p+ layer ([0034]), wherein the doping concentration is 1018 to 1021 atoms/cm3 ([0034]). Ren is analogous to Islam and Alfieri 021 in the field of semiconductor doping.
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to try a doping concentration that is in both the upper end of the range disclosed by Islam and the range disclosed by Ren to form a second epitaxial layer that is a p+ layer with lower contact resistance through routine experimentation (see MPEP § 2144.05).
11. Claims 11-14 and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Islam in view of Alfieri 021, Alfieri 357, and Ren.
Regarding claim 11, Islam discloses a method of forming a silicon carbide (SiC) device (Fig. 2F), the method comprising:
providing a SiC substrate (Fig. 2A 110; [0097]), wherein the SiC substrate (110) is an n+ layer ([0097]);
epitaxially forming a n- layer (Fig. 2 120; [0098]) over an upper surface of the SiC substrate (110); and
epitaxially forming a p layer (Fig. 2 130; [0099]) over the n- layer (120).
Islam fails to disclose passivating the SiC substrate using an ion implant or a plasma doping process and fails to explicitly disclose forming a p+ layer. However, Islam provides a range of doping concentration ([0099]) for the p layer, wherein the concentration is 1×1016 to 1×1019 atoms/cm3 ([0099]).
Alfieri 021 discloses passivating the SiC substrate (Fig. 1B 1; [0071]) using an ion implant (Fig. 1B; [0021], [0022]) or a plasma doping process (Fig. 2; [0021], [0022]) (Specification of instant application discloses that both processes are capable of passivation).
Alfieri 021 fails to disclose passivating the SiC substrate, wherein the SiC substrate is an n+ layer, or epitaxially forming a p+ layer.
Alfieri 357 discloses passivating ([0012], [0041]) the SiC substrate (Fig. 1 11; [0041]), wherein the SiC substrate (11) is an n+ layer ([0016]).
Alfieri 357 fails to disclose epitaxially forming a p+ layer.
Ren discloses forming a second epitaxial layer ([0034]) that is a p+ layer ([0034]), wherein the doping concentration is 1018 to 1021 atoms/cm3 ([0034]).
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to, prior to epitaxially growing the first and second layer, include the step of treating the SiC substrate using the doping processes disclosed by Alfieri 021 to dope the SiC substrate of Islam to alter the electrical conductivity of the substrate for device functionality.
Additionally, it would be obvious to perform the ion implant or plasma doping processes on an n+ SiC substrate/layer, as disclosed by Alfieri 357, for the desired device performance.
Additionally, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to try a doping concentration that is in both the upper end of the range disclosed by Islam and the range disclosed by Ren to form a second epitaxial layer that is a p+ layer with lower contact resistance through routine experimentation (see MPEP § 2144.05).
Regarding claim 12, Islam, Alfieri 021, Alfieri 357, and Ren disclose the method of claim 11, further comprising performing, after the n- layer (120) is epitaxially formed, a second ion implant (Islam Fig. 2B 171; [0100]).
Regarding claim 13¸ Islam, Alfieri 021, Alfieri 357, and Ren disclose the method of claim 11, wherein the ion implant (Alfieri 021 Fig. 1B; [0021], [0022]) comprises delivering hydrogen ions (Alfieri 021 [0024], [0025]) into the upper surface of the SiC substrate (110).
Regarding claim 14, Islam, Alfieri 021, Alfieri 357, and Ren disclose the method of claim 13, wherein the hydrogen ions (Alfieri 021 [0024], [0025]) are delivered while the substrate (110) is at a temperature greater than 15°C (Alfieri 021 [0080]).
Regarding claim 17, Islam, Alfieri 021, Alfieri 357, and Ren disclose the method of claim 1, wherein the SiC substrate (110) is a n+ layer (Islam [0097]).
12. Claims 15-16 are rejected under 35 U.S.C. 103 as being unpatentable over Islam, Alfieri 021, Alfieri 357, and Ren as applied to claim 11 above, and further in view of Li.
Regarding claim 15, Islam, Alfieri 021, Alfieri 357, and Ren disclose the method of claim 11, wherein the plasma doping process (Alfieri 021 Fig. 2; [0021], [0022]) comprises treating the SiC substrate (110).
Islam, Alfieri 021, Alfieri 357, and Ren fail to disclose the plasma doping process comprising of providing hydrogen radicals or deuterium radicals into the upper surface of the SiC substrate (110).
Li discloses a plasma doping process ([0037]) comprising of providing hydrogen plasma ([0038]) into the upper surface ([0036]) of a SiC substrate (0021], [0025]). Li is analogous to Ren in the field of semiconductor doping.
While Li does not explicitly disclose hydrogen radicals, it is known in the art that plasma can form radicals, as evidenced by Bhosle ([0009]), and thus the hydrogen plasma would form hydrogen radicals.
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to substitute the plasma of Islam, Alfieri 021, and Ren with the hydrogen plasma of Li in the plasma doping process to passivate the surface of SiC substrate and yield a predictable result of a passivated SiC substrate with reduced defect density and dangling bonds.
Regarding claim 16, Islam, Alfieri 021, Alfieri 357, Ren, and Li disclose the method of claim 15, wherein the hydrogen radicals (Li [0038]) are provided at a temperature greater than 15°C (Alfieri 021 [0080]).
13. Claims 18-20 are rejected under 35 U.S.C. 103 as being unpatentable over Li in view of Islam and Ren.
Regarding claim 18, Li discloses a system (Fig. 6; [0046]) for forming a silicon carbide (SiC) device, the system comprising:
a first processing chamber (Fig 6. 902; [0046]) comprising:
a plasma doping tool ([0047]) operable to treat the SiC substrate ([0021], [0025]) by performing a plasma doping process ([0037]); and
a second processing chamber (Fig. 6 904; [0046]) operable to:
form a layer ([0046]) over an upper surface of the SiC substrate ([0021], [0025]).
Li fails to explicitly disclose the SiC substrate is an n+ layer, epitaxially forming a n- layer over an upper surface of the SiC substrate after the SiC substrate is treated, and epitaxially form a p+ layer over the n- layer. However, Li discloses the second processing chamber can include a deposition chamber ([0046]).
Islam discloses the SiC substrate (Fig. 2A 110; [0097]) is an n+ layer ([0097]), and forming epitaxially forming a n- layer (Fig. 2A 120; [0098]) over an upper surface of the SiC substrate (110) and epitaxially forming a p layer (Fig. 2 130; [0099]) over the n- layer (120), and forming a SiC device (Fig. 2F).
Islam fails to explicitly disclose forming a p+ layer. However, Islam provides a range of doping concentration ([0099]) for the p layer, wherein the concentration is 1×1016 to 1×1019 atoms/cm3 ([0099]).
Ren discloses forming a second epitaxial layer ([0034]) that is a p+ layer ([0034]), wherein the doping concentration is 1018 to 1021 atoms/cm3 ([0034]).
Thus, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to use the apparatus of Li to perform the method of Islam to form a SiC device. Additionally, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to try a doping concentration that is in both the upper end of the range disclosed by Islam and the range disclosed by Ren to form a second epitaxial layer that is a p+ layer with lower contact resistance through routine experimentation (see MPEP § 2144.05).
Regarding claim 19, Li, Islam, and Ren disclose the system of claim 18, wherein the first processing chamber (902) is further operable to perform, after the n- layer is epitaxially formed (Islam [0098]), a second plasma doping process.
While Li does not explicitly disclose performing this step, it would be obvious to one having ordinary skill in the art before the effective filing date of the claimed invention that the system of Li could transfer the substrate between chambers ([0050]), and could place the substrate in the first processing chamber (902) again for a second plasma doping process to change the electrical properties of the layer to suit the intended device requirements.
Regarding claim 20, Li, Islam, and Ren disclose the system of claim 18, wherein the plasma doping tool ([0047]) is operable to provide hydrogen plasma ([0038]) into the upper surface of the SiC substrate ([0021], [0025]).
While Li does not explicitly disclose hydrogen radicals, it is known in the art that plasma can form radicals, as evidenced by Bhosle, and thus the hydrogen plasma would form hydrogen radicals.
Conclusion
14. The following art made of record and not relied upon is pertinent to applicant’s disclosure.
Bo et al (CN 116053122 A) discloses performing passivation doping treatment on a SiC substrate using hydrogen plasma
THIS ACTION IS MADE FINAL. 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 MICHAEL B SUN whose telephone number is (571)699-0231. The examiner can normally be reached Mon-Fri 8:00-5:00.
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/MICHAEL B SUN/Examiner, Art Unit 2892
/ERIC W JONES/Primary Examiner, Art Unit 2892
