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 .
Information Disclosure Statement
2. 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.
Drawings
3. The drawings are objected to as failing to comply with 37 CFR 1.84(p)(4) because reference character “252” in Fig. 7 has been used to designate both high voltage pulse and RF plasma excitation power supply in Fig. 7. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
The drawings are objected to as failing to comply with 37 CFR 1.84(p)(5) because they do not include the following reference sign(s) mentioned in the description: 254 in paragraph [0032]. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Objections
4. Claim 14 is objected to because of the following informalities: grammar.
Regarding claim 14, “15C” should read “15°C.”
Appropriate correction is required.
Claim 20 is objected to because of the following informalities: clarity. For examination purposes, Claim 20 will be interpreted to read as follows:
The system of claim 18, wherein the ion implanter is operable to deliver hydrogen ions or deuterium ions into the upper surface of the SiC substrate, or wherein the plasma doping tool is operable to provide hydrogen radicals or deuterium radicals into the upper surface of the SiC substrate.
Appropriate correction is required.
Claim Rejections - 35 USC § 103
5. 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.
6. 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.
7. 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 (US 2021/0242021 A1, hereafter Alfieri).
Regarding claim 1, Islam discloses a method, comprising:
providing a silicon carbide (SiC) substrate (Fig. 2A 110; [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 treating the SiC substrate using an ion implant or a plasma doping process.
Alfieri discloses treating the SiC substrate (Fig. 1B 1; [0071]) using an ion implant (Fig. 1B; [0021], [0022]) or a plasma doping process (Fig. 2; [0021], [0022]). Alfieri is analogous to Islam 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 plasma immersion ion implantation method disclosed by Alfieri 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.
Regarding claim 2, Islam and Alfieri 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 and Alfieri disclose the method of claim 1, wherein the ion implant (Alfieri Fig. 1B; [0021], [0022]) comprises delivering hydrogen ions (Alfieri [0024], [0025]) into the upper surface of the SiC substrate (110).
Regarding claim 4, Islam and Alfieri disclose the method of claim 3, wherein the hydrogen ions (Alfieri [0024], [0025]) are delivered while the substrate (110) is at room temperature (between 15 - 40°C) (Alfieri [0080]).
While Alfieri 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 and Alfieri disclose the method of claim 3, wherein the hydrogen ions (Alfieri [0024], [0025]) are delivered while the substrate (110) is at a temperature greater than 40°C (Alfieri [0080]).
Regarding claim 10, Islam and Alfieri disclose the method of claim 1, wherein the second epitaxial layer (130) is formed prior to formation of a device structure (Fig. 2F; [0108]).
8. Claims 6-8 are rejected under 35 U.S.C. 103 as being unpatentable over Islam and Alfieri as applied to claim 1 above, and further in view of Li et al (US 2022/0262619 A1, hereafter Li).
Regarding claim 6, Islam and Alfieri disclose the method of claim 1, wherein the plasma doping process (Alfieri Fig. 2; [0021], [0022]) comprises treating the SiC substrate (110).
Islam and Alfieri 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 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 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, 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 [0080]).
While Alfieri 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, and Li disclose the method of claim 6, wherein the hydrogen radicals (Li [0038]) are provided at a temperature greater than 40°C (Alfieri [080]).
9. Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Islam and Alfieri as applied to claim 1 above, and further in view of Ren et al (US 2021/0098579 A1, hereafter Ren).
Regarding claim 9, Islam and Alfieri disclose the method of claim 1 wherein the SiC substrate (110) is a n+ layer (Islam [0097]), 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 and Alfieri fail to explicitly disclose the second epitaxial layer (130) being a p+ layer. However, Islam and Alfieri disclose 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 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).
10. Claims 11-14 and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Islam in view of Alfieri 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]);
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 treating 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 discloses treating the SiC substrate (Fig. 1B 1; [0071]) using an ion implant (Fig. 1B; [0021], [0022]) or a plasma doping process (Fig. 2; [0021], [0022]).
Alfieri 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 plasma immersion ion implantation method disclosed by Alfieri to dope the SiC substrate of Islam to alter the electrical conductivity of the substrate for device functionality. 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, 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, and Ren disclose the method of claim 11, wherein the ion implant (Alfieri Fig. 1B; [0021], [0022]) comprises delivering hydrogen ions (Alfieri [0024], [0025]) into the upper surface of the SiC substrate (110).
Regarding claim 14, Islam, Alfieri, and Ren disclose the method of claim 13, wherein the hydrogen ions (Alfieri [0024], [0025]) are delivered while the substrate (110) is at a temperature greater than 15°C (Alfieri [0080]).
Regarding claim 17, Islam, Alfieri, and Ren disclose the method of claim 1, wherein the SiC substrate (110) is a n+ layer (Islam [0097]).
11. Claims 15-16 are rejected under 35 U.S.C. 103 as being unpatentable over Islam, Alfieri, and Ren as applied to claim 11 above, and further in view of Li.
Regarding claim 15, Islam, Alfieri, and Ren disclose the method of claim 11, wherein the plasma doping process (Alfieri Fig. 2; [0021], [0022]) comprises treating the SiC substrate (110).
Islam, Alfieri, 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, 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, Alferi, 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 [0080]).
12. 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 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 forming epitaxially forming a n- layer (Fig. 2A 120; [0098]) over an upper surface of the SiC substrate (Fig. 2A 110; [0097]) 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, 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
13. The prior art made of record and not relied upon is considered pertinent to applicant’s disclosure.
Alfieri et al (EP 4089719 A1) discloses a method for doping a silicon carbide substrate via ion beam implantation
Gendron-Hansen et al (US 2021/0225645 A1) discloses a silicon carbide device and method of fabrication
Lichtenwalner et al (US 2018/0166530 A1) discloses a silicon carbide device with n-type doped layers
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
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