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 .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on October 23, 2023 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Drawings
The drawings are objected to as failing to comply with 37 CFR 1.84(p)(4) because reference characters “21”, “22” and “23” have been used to designate “oxide film”. 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)(4) because reference character “11” has been used to designate both “gate insulating film” and “leak current”; and reference character “1” has been used to designate both “drain region” and “substrate”. 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.
Specification
The disclosure is objected to because of the following informalities: 1) Undefined acronyms/symbols, such as “3C”, “4H” ([0003]); “MOS” ([0004]). The examiner suggests that applicant spell out all the acronyms/symbols when using them for the first time in the disclosure; and 2) Typographical error. Changing “nt-type” to “n-type” ([0068]) is suggested. Appropriate correction is required.
The lengthy specification has not been checked to the extent necessary to determine the presence of all possible minor errors. Applicant’s cooperation is requested in correcting any errors of which applicant may become aware in the specification.
Claim Objections
Claims 1-9 are objected to because of the following informalities: a comma (,) should be inserted after “device” (claim 1, line 1); a colon (:) should be inserted after “includes” (claim 1, line 12); and undefined acronyms/symbols, such as “3C” (claim 1, line 15). The examiner suggests that applicant spell out all the acronyms/symbols when using them for the first time in the claim. 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 1-9 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.
The claimed limitation of "silicon carbide", as recited in claim 1, lines 3 and 5, is unclear as to whether said limitation is the same as or different from "silicon carbide", as recited in claim 1, line 2.
The claimed limitation of "a gate insulating film provided inside a trench penetrating the main region and the base region", as recited in claim 1, is unclear as to which element penetrating the main region and the base region applicant refers.
The claimed limitation of "a proportion of the 3C structure included in the source contact part …", as recited in claim 1, is unclear as to a proportion of what of the 3C structure … applicant refers: volume, area, thickness, etc..
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.
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.
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.
Claim(s) 1-9, as best understood, is/are rejected under 35 U.S.C. 103 as being unpatentable over Suzuki et al. (2017/0271507) in view of Tsuchiya (2013/0062622).
As for claims 1 and 2, Suzuki et al. show in Fig. 1 and a related text a silicon carbide semiconductor device 100 comprising:
a drift layer 12 of a first conductivity-type N including silicon carbide ([0025]);
a base region 14 of a second conductivity-type P including silicon carbide provided on a top surface side of the drift layer;
a main region 22/24 of the first conductivity-type including silicon carbide provided on a top surface side of the base region;
a gate insulating film 50 provided inside a trench penetrating the main region and the base region;
a gate electrode 30 buried inside the trench with the gate insulating film interposed; and
a main electrode 34/32 provided in contact with the main region,
wherein the main region includes
a source expansion part 22 with a bottom surface in contact with the base region, and
a source contact part 24 provided on a top surface side of the source expansion part so as to be in contact with the main electrode, and
a top surface of the gate electrode at a position in contact with the gate insulating film is deeper than a bottom surface of the source contact part and is shallower than a bottom surface of the source expansion part.
Suzuki et al. do not disclose the source contact part having a 3C structure (claim 1); and a proportion of the 3C structure included in the source contact part is in a range of 10% or higher and 100% or smaller (claim 2).
Tsuchiya teaches in Fig. 1 and related text:
As for claim 1, the source contact part 15 having a 3C structure ([0038]).
As for claim 2, a proportion of the 3C structure included in the source contact part is in a range of 10% or higher and 100% or smaller ([0038]).
As for claim 3, the source contact part includes phosphorus or arsenic as an impurity ([0030]).
As for claim 4, the source contact part has an impurity concentration in a range of 1 x1019/cm3 or greater and 1 x1022/cm3 or less ([0037]).
As for claims 5, 8 and 9, Suzuki et al. and Tsuchiya disclosed substantially the entire claimed invention, as applied to claim 1 above, including the source contact part has a thickness t (claim 5); the source expansion part has a thickness (claim 8); and a drop amount d3 of the gate electrode from a top surface of the source contact part to the top surface of the gate electrode (claim 3).
Suzuki et al. and Tsuchiya do not disclose the thickness of the source contact part is in a range of 30 nanometers or greater and 100 nanometers or smaller (claim 5); the thickness of the source expansion part is in a range of 150 nanometers or greater and 400 nanometers or smaller (claim 8); and the drop amount of the gate electrode is in a range of 100 nanometers or greater and 300 nanometers or smaller (claim 3)
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to include the thickness of the source contact part being in a range of 30 nanometers or greater and 100 nanometers or smaller; the thickness of the source expansion part being in a range of 150 nanometers or greater and 400 nanometers or smaller; and the drop amount of the gate electrode being in a range of 100 nanometers or greater and 300 nanometers or smaller, in order to improve the performance of the device. Furthermore, it has been held that where then general conditions of a claim are disclosed in the prior art, discovering the optimum or workable ranges involves only routine skill in the art. In re Aller, 105 USPQ 233.
Furthermore, it has been held in that the applicant must show that a particular range is critical, generally by showing that the claimed range achieves unexpected results relative to the prior art range. In re Woodruff, 919 F.2d 1575, 1578, 16 USPQ2d 1934, 1936 (Fed. Cir. 1990). Note that the law is replete with cases in which when the mere difference between the claimed invention and the prior art is some dimensional limitation or other variable within the claims, patentability cannot be found. The instant disclosure does not set forth evidence ascribing unexpected results due to the claimed dimensions. See Gardner v. TEC Systems, Inc., 725 F.2d 1338 (Fed. Cir. 1984), which held that the dimensional limitations failed to point out a feature which performed and operated any differently from the prior art.
As for claim 6, the source expansion part includes nitrogen or phosphorus as an impurity ([0029]).
As for claim 7, the source expansion part has an impurity concentration in a range of 1 x 1016/cm3 or greater and 1 x 1019/cm3 or less ([0037]).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MEIYA LI whose telephone number is (571)270-1572. The examiner can normally be reached Monday-Friday 7AM-3PM.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, LYNNE GURLEY can be reached at (571)272-1670. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/MEIYA LI/Primary Examiner, Art Unit 2811