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 .
Status of the Claims
Group I, Species 1, is elected.
Amendment filed July 16, 2026 is acknowledged. Claim 2 has been cancelled. Claims 1 and 7 have been amended. Non-elected Invention and/or Species, Claims 4, and 6-8 have been withdrawn from consideration. Claims 1 and 3-8 are pending.
Amended claim 1 recites: “in the overlap area, between the first semiconductor region and the one of the plurality of second second-conductivity-type regions in the thickness direction, an other second-conductivity-type region is provided and has a thickness of at most 0.1 µm”.
This limitation directed to non-elected Species, as shown in FIGs. 11-13 and 14-16, respectively.
Note that, the elected Species is clearly claimed in, now cancelled, claim 2: “The silicon carbide semiconductor device according to claim 1, wherein the overlap area is provided in plurality, and respective ones of the plurality of second second-conductivity-type regions are in contact with the first semiconductor region without the other second-conductivity-type region intervening therebetween”.
With the interest of a compact persecution, action on merits of Claims 1, 3 and 5 follows.
Specification
The newly submitted title is not descriptive. The title is
A SILCION CARBIDE SEMICONDUCTOR DEVICE HAVING A VOLTAGE WITHSTANDING STRUCTURE OF SECOND CONDUCTIVITY TYPE OVERLAPPING A SECOND PARALLEL PN LAYER FORMED IN TERMINATION REGION
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1 and 5 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by KAWADA (US. Pub. No. 2021/0167) of record.
With respect to claim 1, KAWADA teaches a silicon carbide semiconductor device, as claimed including:
a semiconductor substrate (42) containing silicon carbide, the semiconductor substrate having a first main surface (40) and a second main surface that are opposite to each other, the semiconductor substrate further having an active region (10) and a termination region (30) surrounding a periphery (20) of the active region;
a first parallel pn layer (67/68) in which a plurality of first first-conductivity-type regions (67) and a plurality of first second-conductivity-type regions (68) are disposed so as to repeatedly alternate with one another in a direction (X) parallel to the first main surface of the semiconductor substrate, the first parallel pn layer being provided in the semiconductor substrate, in the active region (10);
a second parallel pn layer (67/68) in which a plurality of second first-conductivity-type regions (67) and a plurality of second second-conductivity-type regions (68) are disposed so as to repeatedly alternate with one another in the direction (X), the second parallel pn layer being provided in the semiconductor substrate, in the termination region (30);
a device structure provided between the first main surface (40) of the semiconductor substrate and the first parallel pn layer (67/68), in the active region (10);
a first electrode (15) provided on the first main surface (40) of the semiconductor substrate, the first electrode being electrically connected to the device structure;
a second electrode (16) provided on the second main surface of the semiconductor substrate; and
a first semiconductor region (34) of the second conductivity type configuring a voltage withstanding structure and being electrically connected to the first electrode (15), the first semiconductor region (34) being selectively provided between the first main surface (40) of the semiconductor substrate and the second parallel pn layer in the termination region (30), the first semiconductor region (34) surrounding the periphery of the active region (10),
wherein the first semiconductor region (34) has an overlap area where the first semiconductor region (34) and one of the plurality of second second-conductivity-type regions (68) overlap each other in a plan view of the silicon carbide semiconductor device, and
in the overlap area,
between the first semiconductor region (34) and the one of the plurality of second second-conductivity-type regions (68) in the thickness direction (Z), an other second-conductivity-type region (interface region) is provided and has a thickness of at most 0.1 µm. (See FIG. 2).
With respect to claim 5, the silicon carbide semiconductor device of KAWADA further comprises in the first semiconductor region (34), a spatial modulation region in which an impurity concentration distribution of the first semiconductor region (34) decreases in a direction from the active region (10) to the termination region (30).
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.
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over KAWADA ‘167 as applied to claim 1 above, and further in view of KOBAYASHI et al. (US. Pub. No. 2018/0040690) of record.
KAWADA teaches the silicon carbide semiconductor device as described in claim 1 above including: a second semiconductor region (11) of the second conductivity type, provided on the first parallel pn layer (67/68) in the active region (10), the second semiconductor region (11) having a first surface and a second surface opposite to each other, the second surface facing the first parallel pn layer (67/68),
wherein the first semiconductor region (34) has a first surface and a second surface opposite to each other, the second surface facing the second parallel pn layer (67/68).
Thus, KAWADA is shown to teach all the features of the claim with the exception of explicitly disclosing the first surface of the first semiconductor region being closer to the first electrode than is the first surface of the second semiconductor region.
However, KOBAYSAHI teaches a silicon carbide semiconductor device including:
a second semiconductor region (3a) of a second conductivity type provided in active region (1102), the second semiconductor region (3a) having a first surface and a second surface opposite to each other, the second surface facing the drift layer (1),
wherein first semiconductor region (6/7) has a first surface and a second surface opposite to each other, the second surface facing the drift layer (1), the first surface of the first semiconductor region (6/7) being closer to the first electrode (22) than is the first surface of the second semiconductor region (3a). (See FIGs. 5, 7, 9).
Therefore, it would have been obvious to one having ordinary skill in the art at the time of invention was made to form the first semiconductor region of KAWADA having the first surface that is closer to the first electrode than the first surface of the second semiconductor region as taught by KOBAYASHI so that various types of structure may be implemented.
Response to Arguments
Applicant's arguments filed July 16, 2026 have been fully considered but they are not persuasive.
Applicant argues:
Thus, as is also clear from Fig. 2 of Kawada (reproduced above with the JTE structure 34 and the p-type regions 68 highlighted in green and blue respectively), Kawada does not have the feature that in the overlap area, between the first semiconductor region and the one of the plurality of second second-conductivity-type regions in a thickness direction, an other second-conductivity-type region is provided and has a thickness of at most 0.1 µm.
However, as shown in FIG. 2, in the overlap area, between the first semiconductor region 34 and one of the second-second-conductivity-type region 68, there is an interface region, hence, “an other second-conductivity-type region”. This interface region has a thickness of at most 0.1 µm.
Therefore, claim 1 is anticipated by KAWADA.
The rejection of claim 1, 3 and 5 is maintained.
Moreover, as discussed above, the limitation “in the overlap area, between the first semiconductor region and the one of the plurality of second second-conductivity-type regions in a thickness direction, an other second-conductivity-type region is provided and has a thickness of at most 0.1 µm” directs to non-elected Species. Note that, the cancelled claim 2, claimed the elected Species, specifically, cancelled claim 2 recites: “The silicon carbide semiconductor device according to claim 1, wherein the overlap area is provided in plurality, and respective ones of the plurality of second second-conductivity-type regions are in contact with the first semiconductor region without the other second-conductivity-type region intervening therebetween”.
Therefore, the amended claim 1 directs to non-elected Species.
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.
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/ANH D MAI/Primary Examiner, Art Unit 2893
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