DETAILED ACTION
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.
Response to Amendment/Restriction
Applicant’s election without traverse of Group I and Claims 1-6 in the reply filed on August 05, 2025 is acknowledged. Thus, Claims 7-9 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention. Election was made without traverse in the reply filed on August 05, 2025.
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 1-6 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. As to claim 1, the limitation “the bottom of the narrow region” lacks sufficient antecedent basis. Thus, the limitation renders the claims indefinite and clarification is required. As to claim 2, the limitation “the shield area…the bottom of the wide area” lacks sufficient antecedent basis. Thus, the limitation renders the claims indefinite and clarification is required. As to claim 3, the limitation “the wide-width trench” lacks sufficient antecedent basis. Thus, the limitation renders the claim indefinite and clarification is required. As to claim 5, the limitation “a thickness of the shield region is set equal to a depth at which the body region is formed” appears to direct to an intermediate product rather than the final device. As clearly seen in FIG. 6 (f), the depth of the body region 30 is shallower than the shield region 150 and appears to be thicker than the shield region 150. The limitation appears to read on the intermediate product in FIG. 6 (e). It is not clear what the limitation is directed to and thus renders the claim indefinite and clarification is required. As to claim 6, the limitation “the source metal layer” lacks sufficient antecedent basis. Thus, the limitation renders the claim indefinite and clarification is required.
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.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim(s) 1, 3-4, and 6 are rejected under 35 U.S.C. 102(a)(1)(2) as being anticipated by U.S. Patent Application Publication No. 2017/0365709 A1 to Ohashi et al. (“Ohashi”). As to claim 1, Ohashi discloses a silicon carbide power semiconductor device, comprising: a substrate (22) of a first conductivity type (N) made of silicon carbide; a drift layer (24) of the first conductivity type (N) formed on an upper surface of the substrate (22) with a relatively low impurity concentration compared to that of the substrate (22); a body region (26, 32) of a second conductivity type (P) formed in an upper region of the drift layer (24); a different-widths gate trench (under 20 filled by 18), being etched to extend into the drift layer (24) deeper than the body region (26, 32), wherein an upper region (at 20) of the different-widths gate trench (under 20 filled by 18) is formed to be a wide-width region (at 20) with a relatively wider width and a lower region (at 24) of the different-widths gate trench (under 20 filled by 18) is formed to be a narrow-width region (at 24) with a relatively narrower width, wherein the wide-width region (at 20) and the narrow-width region (at 24) share a vertical center line so that the different-widths gate trench (under 20 filled by 18) is formed in a boundary shape bent to have a stepped edge; a different-widths poly gate electrode (18) filled in the different-widths gate trench (under 20 filled by 18) so as to be insulated by a different-widths gate oxide (16) and formed in a shape corresponding to the shape of the different-widths gate trench (under 20 filled by 18); and a source region (28) of the first conductivity type (N) formed in an upper region of the body region (26, 32) in contact with sidewalls of the different-widths gate trench (under 20 filled by 18), wherein the different-widths gate oxide (16) formed on the bottom of the narrow region of the different-widths gate trench (under 20 filled by 18) is formed to be twice or more thicker than a thickness of the different-widths gate oxide (16) formed on the sidewall of the wide-width region (at 20), wherein a shield region (26 in contact with 16) of the second conductivity type (P) is formed at both corner regions of the different-widths gate trench (under 20 filled by 18) where the bottom of the wide-width region (at 20) and sidewalls of the narrow-width region (at 24) cross (See Fig. 1, Fig. 23, Fig. 25, ¶ 0040, ¶ 0045, ¶ 0048, ¶ 0051, ¶ 0055, ¶ 0058, ¶ 0059, ¶ 0061, ¶ 0062, ¶ 0064, ¶ 0069, ¶ 0075, ¶ 0076, ¶ 0165, ¶ 0168, ¶ 0178, ¶ 0180). As to claim 3, Ohashi further discloses wherein the body region (26, 32) and the shield region (26 in contact with 16) are formed together as an extension region of the second conductivity type (P) in a state of being connected to each other at a same process and then separated from each other in an etching process in which the drift layer (24) is etched to form the wide-width trench (at 20) for forming the wide-width region (at 20) (See Fig. 25). Furthermore, the limitation “are formed together as an extension region of the second conductivity type in a state of being connected to each other at a same process and then separated from each other in an etching process in which the drift layer is etched to form the wide-width trench for forming the wide-width region” is a product-by-process limitation that does not structurally distinguish the claimed invention over the prior art. It has been held it has been held that “The Patent Office bears a lesser burden of proof in making out a case of prima facie obviousness for product-by-process claims because of their peculiar nature” than when a product is claimed in the conventional fashion. In re Fessmann, 489 F.2d 742, 744, 180 USPQ 324, 326 (CCPA 1974). Once the examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious difference between the claimed product and the prior art product. In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983). The structure implied by the process steps should be considered when assessing the patentability of product-by-process claims over the prior art, especially where the product can only be defined by the process steps by which the product is made, or where the manufacturing process steps would be expected to impart distinctive structural characteristics to the final product. See, e.g., In re Garnero, 412 F.2d 276, 279, 162 USPQ 221, 223 (CCPA 1979). As to claim 4, Ohashi further discloses wherein the body region (26, 32) and the shield region (26 in contact with 16) are formed with the same impurity concentration (26 concentration) (See Fig. 25). As to claim 6, Ohashi discloses wherein further comprising a contact region (26 side) of the second conductivity type (P) formed in the upper region of the body region (26, 32) to contact the source region (28), wherein the contact region (26 side) is bonded to the source metal layer with a recess-etched contact structure (See Fig. 23).
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) 1-4 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Application Publication No. 2022/0157959 A1 to Kim et al. (“Kim”) in view of U.S. Patent Application Publication No. 2004/0150038 A1 to Hsieh et al. (“Hsieh”). As to claim 1, although Kim discloses a silicon carbide power semiconductor device, comprising: a substrate (110) of a first conductivity type (N) made of silicon carbide; a drift layer (120) of the first conductivity type (N) formed on an upper surface of the substrate (110) with a relatively low impurity concentration compared to that of the substrate (110); a body region (170) of a second conductivity type (P) formed in an upper region of the drift layer (120); a different-widths gate trench (580), being etched to extend into the drift layer (120) deeper than the body region (170), wherein an upper region of the different-widths gate trench (580) is formed to be a wide-width region (581) with a relatively wider width and a lower region (582) of the different-widths gate trench (580) is formed to be a narrow-width region (582) with a relatively narrower width, wherein the wide-width region (581) and the narrow-width region (582) share a vertical center line so that the different-widths gate trench (580) is formed in a boundary shape bent to have a stepped edge; a different-widths poly gate electrode (584) filled in the different-widths gate trench (580) so as to be insulated by a different-widths gate oxide (586) and formed in a shape corresponding to the shape of the different-widths gate trench (580); and a source region (160) of the first conductivity type (N) formed in an upper region of the body region (170) in contact with sidewalls of the different-widths gate trench (580), wherein a shield region (540) of the second conductivity type (P) is formed at both corner regions of the different-widths gate trench (580) where the bottom of the wide-width region (581) and sidewalls of the narrow-width region (582) cross (See Fig. 2, Fig. 4, Fig. 5, ¶ 0070-¶ 0073, ¶ 0075, ¶ 0078-¶ 0080, ¶ 0099, ¶ 0105, ¶ 0112-¶ 0121), Kim does not further disclose wherein the different-widths gate oxide formed on the bottom of the narrow region of the different-widths gate trench is formed to be twice or more thicker than a thickness of the different-widths gate oxide formed on the sidewall of the wide-width region. However, Hsieh does disclose wherein the different-widths gate oxide (210t) formed on the bottom of the narrow region of the different-widths gate trench (206) is formed to be twice or more thicker than a thickness of the different-widths gate oxide (210t) formed on the sidewall of the wide-width region (See Fig. 2, Fig. 3, ¶ 0007, ¶ 0018, ¶ 0019, ¶ 0038, ¶ 0042). In view of the teaching of Hsieh, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the teaching of Kim to have wherein the different-widths gate oxide formed on the bottom of the narrow region of the different-widths gate trench is formed to be twice or more thicker than a thickness of the different-widths gate oxide formed on the sidewall of the wide-width region because the thicker gate oxide still maintains the gate function while reducing the gate charges and avoiding high interface state charges (See ¶ 0042). As to claim 2, Kim further discloses wherein the shield area is formed to extend in a downward direction in contact with the bottom of the wide area as a whole, wherein the shield area is in contact with sidewall of the narrow-width region (582) to a same depth as a bottom of the different-widths poly gate electrode (584) located in the narrow-width region (582) in the different-widths gate trench (580) (See Fig. 5, ¶ 0116). As to claim 3, Kim further discloses wherein the body region (170) and the shield region (540) are formed together as an extension region of the second conductivity type (P) in a state of being connected to each other at a same process and then separated from each other in an etching process in which the drift layer (120) is etched to form the wide-width trench for forming the wide-width region (581) (See Fig. 5). Furthermore, the limitation “are formed together as an extension region of the second conductivity type in a state of being connected to each other at a same process and then separated from each other in an etching process in which the drift layer is etched to form the wide-width trench for forming the wide-width region” is a product-by-process limitation that does not structurally distinguish the claimed invention over the prior art. It has been held it has been held that “The Patent Office bears a lesser burden of proof in making out a case of prima facie obviousness for product-by-process claims because of their peculiar nature” than when a product is claimed in the conventional fashion. In re Fessmann, 489 F.2d 742, 744, 180 USPQ 324, 326 (CCPA 1974). Once the examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing an unobvious difference between the claimed product and the prior art product. In re Marosi, 710 F.2d 798, 802, 218 USPQ 289, 292 (Fed. Cir. 1983). The structure implied by the process steps should be considered when assessing the patentability of product-by-process claims over the prior art, especially where the product can only be defined by the process steps by which the product is made, or where the manufacturing process steps would be expected to impart distinctive structural characteristics to the final product. See, e.g., In re Garnero, 412 F.2d 276, 279, 162 USPQ 221, 223 (CCPA 1979). As to claim 4, Kim further discloses wherein the body region (170) and the shield region (540) are formed with the same impurity concentration (See Fig. 4, ¶ 0105).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DAVID CHEN whose telephone number is (571)270-7438. The examiner can normally be reached M-F 12-6.
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/DAVID CHEN/Primary Examiner, Art Unit 2815