DETAILED ACTION
Election/Restrictions
Applicant’s election without traverse of species B/fig. 3, 5, 8-9, reflected in claims 11-20 in the reply filed on 08/21/2025 is acknowledged. Claims 1-10 are withdrawn from further consideration pursuant to 37 CFR 1.142 (b), as being drawn to the nonelected group.
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 15-16 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.
Claims 15 and 16 recite the limitations “said buffer region”. There is insufficient antecedent basis for this limitation in the claim.
Claims 15 and 16 recite limitations, ‘a buffer epitaxial layer’, ‘said epitaxial layer’. Claims 15 and 16 further recite, “said epitaxial layer in said buffer region..”. Referring to these claims and associated figures of the applicant, this is not understood, whether epitaxial layer or the epitaxial layer is meant to have doping concentration than each of said MSE layers.
Claim Rejections - 35 USC § 102
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 (i.e., changing from AIA to pre-AIA ) 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.
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 11, 12, 17 and 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Hsieh (US 20170317207 A1, hereinafter Hsieh‘207).
Regarding independent claim 11, Hsieh‘207 teaches, “A shielded gate trench (SGT) device comprising a plurality of unit cells with each unit cell in an active area (fig. 1-22; ¶ [0045] - ¶ [0066]), comprising:
a gate trench (234, fig. 2, fig. 6) having a hexagonal shape (¶ [0013]) and surrounding a deep trench (235) with a hexagonal shape (Abstract) wherein a first type shielded gate electrode (236) is formed within said deep trench (235) and surrounded by a first insulating film (237);
a source-body contact (245) with a hexagonal shape (fig. 6, ‘trenched source-body contact’ has same shape of the gate trench and the deep trench) disposed between said gate trench (234) and said deep trench (235);
an epitaxial layer (231) of said first conductivity type (N) grown on a substrate (232);
said deep trench (235) having deeper trench depth than said gate trench (234); and
said gate trench (234) surrounded by a source region (240) of said first conductivity type (N) is encompassed in a body region (241) of a second conductivity type (P) near a top surface of said epitaxial layer (231)”.
Regarding claim 13, Hsieh‘207 teaches, “13. The SGT device of claim 11, wherein said epitaxial layer (231) is a single epitaxial layer with a uniform doping concentration”.
Regarding claim 17, Hsieh‘207 teaches, “The SGT device of claim 11, wherein said substrate (232) has said first conductivity type (N)”.
Regarding claim 20, Hsieh‘207 teaches, “The SGT device of claim 11, wherein a bottom of said deep trench (235) is located above or below a top surface of said substrate (232)”.
Claim Rejections - 35 USC § 103
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 (i.e., changing from AIA to pre-AIA ) 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.
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.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Hsieh‘207 as applied to claim 11 above, and further in view of BURKE; Peter A. et al. (US 20190067427 A1, hereinafter Burke‘427).
Regarding claim 12, Hsieh‘207 teaches all the limitations described in claim 11.
But Hsieh‘207 is silent upon the provision of wherein, the SGT device of claim 11, wherein said gate trench is filled with a gate electrode and a second type shielded gate electrode; said second type shielded gate electrode is insulated from said epitaxial layer by a second insulating film, said gate electrode is insulated from said epitaxial layer by a gate oxide, said second type shielded gate electrode and said gate electrode are insulated from each other by an (Inter-Poly Oxide) IPO film, said gate oxide surrounds said gate electrode and has less thickness than said second insulating film.
However, Burke‘427 teaches a similar device (fig. 1), wherein said gate trench is filled with a gate electrode (110) and a second type shielded gate electrode (106); said second type shielded gate electrode (106) is insulated from said epitaxial layer (116/200) by a second insulating film (104), said gate electrode (110) is insulated from said epitaxial layer (116/200) by a gate oxide (104), said second type shielded gate electrode (106) and said gate electrode (110) are insulated from each other by an (Inter-Poly Oxide) IPO film (108), said gate oxide (104) surrounds said gate electrode (110) and has less thickness than said second insulating film (104).
Hsieh‘207 and Burke‘427 are analogous art because they both are directed to semiconductor devices and one of ordinary skill in the art would have had a reasonable expectation of success to modify Hsieh‘207 with the features of Burke‘427 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 filling date of the invention to combine the teachings of Hsieh‘207 and Burke‘427 to include shielded gate electrode and IP film as shielded gate electrode “exhibit reduced gate-to-drain capacitance, C.sub.gd, reduced on-resistance, R.sub.ds(on), and increased breakdown voltage” (¶ [0003], Burke‘427) and IPO “reduces the number of processes in the production of shielded gate MOSFETs, which decreases costs and increases reliability” (¶ [0005], Burke‘427).
Claims 14 and 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over Hsieh‘207 as applied to claim 11 above, and further in view of YOSHIKAWA et al. (US 20210384330 A1, hereinafter Yoshikawa‘330).
Regarding claim 14, Hsieh‘207 teaches all the limitations described in claim 11.
But Hsieh‘207 is silent upon the provision of wherein said epitaxial layer has multiple stepped epitaxial (MSE) layers with doping concentrations decreasing stepwise in a direction from said substrate toward said body region along sidewalls of said deep trench.
However, Yoshikawa‘330 teaches a similar device (fig. 3), wherein said epitaxial layer (18) has multiple stepped epitaxial (MSE) layers (108, 19) with doping concentrations decreasing stepwise in a direction from said substrate (82, 22) toward said body region (14) along sidewalls of said deep trench (30, 40).
Hsieh‘207 and Yoshikawa‘330 are analogous art because they both are directed to semiconductor devices and one of ordinary skill in the art would have had a reasonable expectation of success to modify Hsieh‘207 with the features of Yoshikawa‘330 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 filling date of the invention to combine the teachings of Hsieh‘207 and Yoshikawa‘330 to include stepped drift layer with a general motivation of ensuring uniform electric field, avoiding field crowding etc.
Regarding claim 18, “The SGT device of claim 11, wherein said substrate has said second conductivity type”, Hsieh‘207 teaches ‘an N-channel trench MOSFET 230’, ‘an N+ substrate’. This is known in the related field that for a P-channel trench MOSFET, the substrate will be opposite polarity, i.e., second conductivity type (p). Yoshikawa‘330 also teaches second conductivity type substrate has in fig. 2.
Regarding claim 19, Hsieh‘207 and Yoshikawa‘330 further teach, “The SGT device of claim 18, further comprising a plurality of heavily doped regions of said first conductivity type in said substrate to form a plurality of alternating P+ and N+ regions (22, 82, fig. 3, ) in said substrate”.
Examiner’s Note
Applicant is reminded that the Examiner is entitled to give the broadest reasonable interpretation to the language of the claims. Furthermore, the Examiner is not limited to Applicants' definition which is not specifically set forth in the claims. See MPEP 2111, 2123, 2125, 2141.02 VI, and 2182.
Examiner has cited particular columns and line numbers in the references applied to the claims above for the convenience of the applicant. Although the specified citations are representative of the teachings of the art and are applied to specific limitations within the individual claim, other passages and figures may apply as well. It is respectfully requested from the applicant in preparing responses, to fully consider the references in their entirety as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or disclosed by the Examiner. See MPEP 2141.02 VI.
In the case of amending the claimed invention, Applicant is respectfully requested to indicate the portion(s) of the specification which dictate(s) the structure relied on for proper interpretation and also to verify and ascertain the metes and bounds of the claimed invention.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MOHAMMAD M HOQUE whose telephone number is (571)272-6266 and email address is mohammad.hoque@uspto.gov. The examiner can normally be reached 9AM-7PM EST.
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/MOHAMMAD M HOQUE/Primary Examiner, Art Unit 2817