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 .
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 “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.
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 “3C-SiC”, as recited in claim 2, is unclear as to whether said limitation is the same as or different from “3C-SiC”, as recited in claim 1.
The claimed limitation of “a surface”, as recited in claim 2, is unclear as to whether said limitation is the same as or different from “a bottom surface”, as recited in claim 1.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim(s) 1-11, as best understood, is/are rejected under 35 U.S.C. 103 as being unpatentable over Takeuchi et al. (2021/0384343) in view of Suzuki et al. (2017/0271507) and Tsuchiya (2013/0062622).
As for claims 1, 2 and 3, Taeuchi et al. show in Fig. 1 and a related text a silicon carbide semiconductor device, comprising:
a drift layer 2 of a first conductivity-type N including silicon carbide ([0041]);
a base region 6 of a second conductivity-type P including silicon carbide provided on a top surface side of the drift layer ([0051]);
a main region 8 of the first conductivity-type including silicon carbide provided on a top surface side of the base region ([0042]);
a gate insulating film 12 provided inside a trench 11, the trench penetrating the main region and the base region;
a gate electrode 13 buried inside the trench with the gate insulating film interposed; and
a main electrode 15 provided in contact with the main region,
wherein the main region includes:
a source expansion part 8a with a bottom surface in contact with the base region, and
a source contact part 8b provided on a top surface side of the source expansion part and in contact with the main electrode, and
no silicide layer is provided between the source contact part and the main electrode.
Takeuchi et al. do not disclose the source contact part including cubic silicon carbide (3C-SiC); 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 (claim 1); a proportion of an area of 3C-SiC on a surface of the source contact part is in a range of 10% or higher and 100% or smaller (claim 2); and the source contact part includes phosphorus or arsenic as an impurity (claim 3).
Suzuki et al. teach in Fig. 1 and related text:
As for claim 1, a top surface of the gate electrode 30 at a position in contact with the gate insulating film 50 is deeper than a bottom surface of the source contact part 24 and is shallower than a bottom surface of the source expansion part 22.
As for claim 3, the source contact part includes phosphorus or arsenic as an impurity ([0030]).
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 an area of 3C-SiC on a surface of the source contact part is in a range of 10% or higher and 100% or smaller ([0038]).
Takeuchi et al., Suzuki et al. and Tsuchiya et al. are analogous art because they are directed to a silicon carbide semiconductor device and one of ordinary skill in the art would have had a reasonable expectation of success to modify Takeuchi et al. with the specified feature(s) of Suzuki et al. and Tsuchiya et al. because they are from the same field of endeavor.
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 source contact part including cubic silicon carbide (3C-SiC); and a proportion of an area of 3C-SiC on a surface of the source contact part being in a range of 10% or higher and 100% or smaller, as taught by Tsuchiya et al., a top surface of the gate electrode at a position in contact with the gate insulating film being deeper than a bottom surface of the source contact part and being shallower than a bottom surface of the source expansion part; and the source contact part including phosphorus or arsenic as an impurity, as taught by Suzuki et al., in Takeuchi et al.'s device, in order to reduce leakage current and improve performance of the device. Furthermore, it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use as a matter of obvious design choice. In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960).
As for claim 4, the combined device shows the source contact part has an impurity concentration in a range of 1 x1019/cm3 or greater and 1 x1022/cm3 or less (Takeuchi: [0054]).
As for claims 5, 8 and 9, Takeuchi et al., 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 (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).
Takeuchi et al., 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 combined device shows the source expansion part includes nitrogen or phosphorus as an impurity (Takeuchi: [0088]).
As for claim 7, the combined device shows 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 (Takeuchi: [0053]).
As for claim 10, the combined device shows the main electrode includes a barrier metal layer as a lower layer and a source wiring electrode as an upper layer, and the barrier metal layer is directly in contact with the source contact part (Takeuchi: [0063]).
As for claim 11, the combined device shows a thickness of the source contact part is less than a thickness of the source expansion part (Takeuchi: [0053]-[0054]).
Response to Arguments
Applicant's arguments filed May 4, 2026 have been fully considered but they are not persuasive.
Applicant argues that the claimed limitation of "silicon carbide", as recited in claim 1, is clear.
"Silicon carbide" is recited multiple times in the same claim. Therefore, it is unclear as to which silicon carbide applicant refers.
Rest of applicant’s arguments with respect to claim(s) 1-9 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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 MEIYA LI whose telephone number is (571)270-1572. The examiner can normally be reached Monday-Friday 7AM-3PM.
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/MEIYA LI/Primary Examiner, Art Unit 2811
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