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 .
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 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.
Election/Restrictions
Applicant's election without traverse of Species S directed to Figs. 21A-21C (Claims 1-10) in the reply filed on January 16th, 2026 is acknowledged.
Claims 11-15 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected Species, there being no allowable generic or linking claim.
Claim Objections
Claims 1, 4-5, and 9-10 are objected to because of the following informalities:
Claim 1 recites “the semiconductor body” in line 4 refers back to “a SiC semiconductor body” in line 3 and should be amended to “the SiC semiconductor body” for avoiding confusion. Appropriate correction is required.
Claim 1 recites “the mesa regions” in lines 7, 12-13 and 14-15 refers back to “a plurality of mesa regions” in line 6 and should be amended to “the plurality of mesa regions” for avoiding confusion. Appropriate correction is required.
Claim 1 recites “the trenches” in line 12 refers back to “a plurality of trenches” in line 2 and should be amended to “the plurality of trenches” for avoiding confusion. Appropriate correction is required.
Claim 4 recites “the elongated mask sections” in line 1 refers back to “a plurality of elongated mask sections” in lines 1-2 of claim 3 and should be amended to “the plurality of elongated mask sections” for avoiding confusion. Appropriate correction is required.
Claim 5 recites “the trenches” in line 4 refers back to “a plurality of trenches” in line 2 of claim 1 and should be amended to “the plurality of trenches” for avoiding confusion. Appropriate correction is required.
Claim 9 recites “the mesa regions” in line 2 refers back to “a plurality of mesa regions” in line 6 of claim 1 and should be amended to “the plurality of mesa regions” for avoiding confusion. Appropriate correction is required.
Claim 10 recites “the mesa regions” in line 1 refers back to “a plurality of mesa regions” in line 6 of claim 1 and should be amended to “the plurality of mesa regions” for avoiding confusion. 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.
Claims 1-10 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 pre-AIA the applicant regards as the invention.
Claim 1 recites “a second doping type” in line 12 without reciting “ a first doping type”. It is unclear to the examiner how can the second doping type being formed before having the first doping type.
Claims 2-10 are also rejected for being depended on claim 1 for having the above issues incorporating into the claims.
Claim 2 recites a redundant “an implantation mask” in line 2 because claim 1 already recites “an implantation mask” in lines 15-16.
Claim 3 recites “second lateral direction” in line 3 without reciting “first lateral direction”. It is unclear to the examiner how can second lateral direction being determined before having first lateral direction.
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 of this title, 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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
a. Determining the scope and contents of the prior art.
b. Ascertaining the differences between the prior art and the claims at issue.
c. Resolving the level of ordinary skill in the pertinent art.
d. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-2 and 6-9 are rejected under 35 U.S.C. 103 as being unpatentable over HSIEH et al. (Pub. No.: US 2016/0163789 A1), hereinafter as HSIEH and in view of MATSUNAGA (Pub. No.: US 2022/0254919 A1).
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Regarding claim 1, HSIEH discloses a method in Fig. 2A and 4A-4K, comprising: forming a trench structure with a plurality of trenches (plurality of trenches 204) in an inner region (cell region as shown in Fig. 4a above) and an edge region (termination area as shown in Fig. 4a above) of a semiconductor body (substrate 202 and layer 201) such that the trench structure extends from a first surface of the semiconductor body (top surface of layer 201) through a second semiconductor layer (layer 201) into a first semiconductor layer (substrate 202) and such that the trench structure, in the second semiconductor layer, forms a plurality of mesa regions (mesa between every two adjacent trenches 204) (see Fig. 2A, 4A above and [0040], [0045-0046]); and forming at least one transistor cell (trench MOSFET) at least partially in each of the mesa regions in the inner region (see Fig. 2A, 4K and [0040]), wherein forming each transistor cell comprises forming at least one compensation region (region 207), wherein forming the at least one compensation region comprises implanting dopant atoms of a second doping type (dopant of p-type) via sidewalls of the trenches into the mesa regions in the inner region (see Fig. 4D and [0048]), and wherein forming the at least one compensation region in each of the mesa regions in the inner region comprises at least partially covering the edge region with an implantation mask (mask 270 and pad oxide 271) (see Figs. 4B-4D and [0046-0050]).
HSIEH fails to disclose the semiconductor body is made of SiC.
MATSUNAGA discloses a method of forming a semiconductor device comprising a SiC semiconductor body (silicon carbide semiconductor base 18) (see Fig. 1 and [0073]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention incorporating the silicon carbide material of the method of MATSUNAGA into the method of HSIEH for making SiC semiconductor body because having Silicon carbide as material for making trench MOSFET would provide advantages of using the transistor under higher temperature environments and with higher breakdown voltage and further reduce device resistance in an ON stage.
Regarding claim 2, the combination of HSIEH and MATSUNAGA discloses the method of claim 1, wherein at least partially covering the edge region with an implantation mask comprises completely covering the edge region with the implantation mask (all covered by mask 270 and pad oxide 271 in the edge region) (see annotated Fig. 4A above of HSIEH).
Regarding claim 6, the combination of HSIEH and MATSUNAGA discloses the method of claim 1, wherein forming each transistor cell further comprises: forming a drift region of a first doping type (forming column region 206 of N-type) complementary to the second doping type adjacent to the compensation region (see Figs. 4C-4D and [0047-0048])
Regarding claim 7, the combination of HSIEH and MATSUNAGA discloses the method of claim 6, wherein forming the drift region comprises: implanting dopant atoms of the first doping type (boron dopant) via the sidewall of a respective trench into a respective mesa region (see Figs. 4C-4D and [0047-0048]).
Regarding claim 8, the combination of HSIEH and MATSUNAGA discloses the method of claim 7, wherein the compensation region and the drift region of each transistor cell are formed such that they are adjacent in a direction that is perpendicular to the sidewall (see Fig. 4D and [0048]).
Regarding claim 9, the combination of HSIEH and MATSUNAGA discloses the method of claim 6, wherein the second semiconductor layer has a basic doping of the first doping type (layer 201 was grown with N-type as basic doping) so that the mesa regions have a basic doping of the first doping type, and wherein the drift region is formed by a basic doped section of a respective mesa region (region 206) (see Fig. 4B-4C and [0040], [0045]).
Allowable Subject Matter
Claims 3-5 and 10 are objected to as being dependent upon a rejected base claim, but would be allowable if amended to overcome 112 rejections and the objection under formalities and rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is an examiner's statement of reasons for the indication of allowable subject matter:
Wherein the implantation mask comprises a plurality of elongated mask sections that laterally extend in a first direction and that are spaced apart from each other in a second lateral direction, and wherein the trenches laterally extend in the second lateral direction as recited in claim 3.
Further comprising: forming a field-stop region of a first doping type complementary to the second doping type in the edge region; and forming the trenches such that lateral ends of the trenches are located in the field-stop region as recited in claim 5
Wherein a width of the mesa regions is narrower in the edge region than in the inner region as recited in claim 10.
Claim 4 depend on claim 3, and therefore also include said claimed limitation.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to CUONG B NGUYEN whose telephone number is (571)270-1509 (Email: CuongB.Nguyen@uspto.gov). The examiner can normally be reached Monday-Friday, 8:30 AM-5:00 PM Eastern Standard Time.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Steven H. Loke can be reached on (571) 272-1657. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/CUONG B NGUYEN/Primary Examiner, Art Unit 2818