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 .
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(s) 1, and 5-10 is/are rejected under 35 U.S.C. 102(a)(1) and (a)(2) as being anticipated by Hsieh (US 2021/0028305 A1) (“Hsieh”), and/or in view of Bowers (US 2013/0234241 A1) (“Bowers”)
Regarding claim 1, Hsieh teaches at least in figure 4:
a substrate (900);
an epitaxial layer (902/940), formed on the substrate (900) and having a trench (906),
wherein the trench (906) has two vertical sidewalls (906 has two vertical sidewalls as shown in figure 4); and
a split gate structure (908), disposed in the trench (906) and comprising (detailed below):
a shielding gate (907), located inside the trench (906);
a first top gate (left 908) and a second top gate (right 908), respectively disposed above the shielding gate (907),
wherein each of the first top gate (left 908) and the second top gate (right 908) has a shape that is wide at top and narrow at bottom (908’s are wider at top and narrower on the bottom) (Examiner note: based upon US 2013/0234241 A1 and US 2017/0338309 A1 the shape of the split top gate structure is a change in size/proportion and/or a change in shape under MPEP 2144.04(A) and (B). However, Examiner is not using this as a basis of rejection as Hsieh already teaches this limitation);
a surface of the first top gate (left 908) and a surface of the second top gate (right 908) close to the two vertical sidewalls of the trench (sidewalls of 906) are flat surfaces (they are so flat),
a gate oxide layer (909-2/part of 931 between 908 and 907; hereinafter “A”), located between the first top gate and the trench and between the second top gate and the trench (A is located between each 908 and 907);
a shielding oxide layer (906 between 907 and the left and right side of the trench; hereinafter “B”), located between the shielding gate (907) and the trench (906); and
an inter-gate oxide layer (931), located between the shielding gate (906), the first top gate, and the second top gate (908s).
Wherein the inter-gate oxide layer (931) between the first top gate (left 908) and the second top gate (right 908) has a top and a bottom (931 has a top near 909-1 and a bottom near the bottom of 931).
Hsieh does not teach:
a surface of the first top gate and a surface of the second top gate away from the two vertical sidewalls of the trench comprise symmetrical inclined surfaces; and
Wherein the inter-gate oxide layer in a cross-sectional view, the top is narrower than the bottom.
However, this is considered a change in size or proportion under MPEP 2144.04(IV)(A). Under MPEP 2144.04(IV)(A), the court in In Gardner v.TEC Syst., Inc., 725 F.2d 1338, 220 USPQ 777 (Fed. Cir. 1984), cert. denied, 469 U.S. 830, 225 USPQ 232 (1984) held that where the only difference between the prior art and the claims was a recitation of relative dimensions of the claimed device and a device having the claimed relative dimensions would not perform differently than the prior art device, the claimed device was not patentably distinct from the prior art device.
Here the difference in the claimed relative dimensions are the inner sides of the first top gate and second top gate. Applicant states that their claimed inner sides of the above elements are formed by an oxide dry etching. Remarks at pg. 6. However, Applicant does assert or contend that this relative dimension performs the function of a gate electrode differently than the prior art. Therefore, This limitation is not patentably distinct from the prior art.
Additionally, or alternatively, the above limitation can be considered a change in shape under MPEP 2144.04(IV)(B). Under MPEP 2144.04(IV)(B), the court in In re Dailey, 357 F.2d 669, 149 USPQ 47 (CCPA 1966) held that the configuration, or shape, of the claimed device was a matter of choice which a person of ordinary skill in the art would have found obvious absent persuasive evidence that the particular configuration of the claimed shape was significant.
Bowers teaches that the shape of the split gates (172) reduce the gate-drain capacitance. ¶ 0025. And, it will also reduce the on-resistance. Id. Further, Bowers teaches that the drawings are representative drawings and that differences in design dimensions can result in different shapes. ¶ 0018. Thus, based upon Bowers the only difference between the prior art and the claimed structure is a recitation of the shape of the claimed device. There is no evidence that the claimed device would act differently based upon the teachings of Bowers. MPEP 2144.04(A)(B).
Regarding claim 5, Hsieh teaches at least in figure 4:
wherein a bottom surface of the first top gate and a bottom surface of the second top gate are both flat surfaces (this is shown in figure 4).
Regarding claim 6, Hsieh teaches at least in figure 4:
a body region (one or more of 910/912/913), formed in the epitaxial layer (902/940); and
a source region (911), formed in the body region (910/912/913) and close to a top surface of the epitaxial layer (911 is close to 902/940).
Regarding claim 7, Hsieh teaches at least in figure 4:
wherein the gate oxide layer (A) also extends over the source region (911).
Regarding claim 8, Hsieh teaches at least in figure 4:
herein the body region (one or more of 910/912/913) and the source region (911) have different conductivity (the body is p-type and the source is n-type).
Regarding claim 9, Hsieh teaches at least in figure 4:
a drain electrode (901), disposed on a bottom portion of the substrate (900).
Regarding claim 10, Hsieh teaches at least in figure 4:
wherein the gate oxide layer (A) also extends to a top surface of the epitaxial layer (911; where the top surface of the epitaxial layer is also the top surface of the source region).
Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hsieh, in view of Bowers, in view of Zeng et al. (US 2020/0273987 A1) (“Zeng”).
Regarding claim 4, Hsieh does not teach:
wherein a projection of the shielding gate (907) on the substrate (900) partially overlaps with a projection of the first top gate on the substrate, and the projection of the shielding gate on the substrate partially overlaps with a projection of the second top gate on the substrate.
Zeng teaches at least in figures 20-21, 25, 27-32
wherein a projection of the shielding gate (34) on the substrate (24) partially overlaps with a projection of the first top gate (left 56) on the substrate (24), and the projection of the shielding gate (34) on the substrate partially overlaps with a projection of the second top gate (right 56) on the substrate (24).
It would have been obvious to combine Zeng with Hsieh for the reasons and rational stated in claim 1 in that based upon the rational/reasons of claim 1 and Zeng whether to have the shielding gate overlap with the first and second top gate is an obvious variant based upon the relative dimensions of the first and second top gate and shielding gate, and/or a change in size and shape of the first top gate, second top gate, and shielding gate. Zheng shows in a plurality of figures that one can change the above relative dimensions and/or shape and the device would continue to work.
Response to Arguments
Applicant’s arguments filed December 8, 2025, are not persuasive. Applicant’s argument is that the prior art does not teach the relative dimension, and/or shape, of the inter-gate oxide layer such that the top of the inter-gate oxide layer is narrower than the bottom. This argument is not persuasive for the reasons stated in the analysis of the claim above.
Based upon Applicant’s arguments it appears that claim 1 hinges, or centers around, the limitation “wherein the inter-gate oxide layer between the first top gate and the second top gate has a top and a bottom, and in a cross-sectional view, the top is narrower than the bottom.”
Applicant’s position appears to be the none of the prior art actually shows this limitation. Applicant points to Hsieh figure 4 which shows the inner-gate oxide layer has vertical walls, and Bowers figure 1 and Zeng figures 14-15 and 20 which also do not show this limitation.
However, it appears that Applicant has not commented on Bowers ¶ 0018 which states “[p]rocessing variations in aspect ratios, differences in design dimensions, and/or so forth can result in different shapes and/or non-idealities.” This means that one of ordinary skill it the art is free to change the shape of any part of the device even if it is not ideal to do so. Examiner in the rejection of claim 1 stated that one can consider the sidewall of the inter-gate oxide as a change in size or proportion under MPEP 2144.04(IV)(A). This argument is possible because Bowers explicitly allows for changes in size or proportions to include non-ideal (i.e. disfavored) sizes or proportions. Applicant has not responded with how their claimed device will perform differently from the prior art device. Therefore, Applicant’s claimed device is not patently distinct from the prior art. Further, Examiner under MPEP 2144.04(IV)(B) stated that Bowers teaches that the shape of the split gates, which directly influences the shape of the inter-gate oxide, can reduce, and by extension increase, the gate-drain capacitance and also reduce, by the same extension increase, the on-resistance of the device. Further, as previously stated, Bowers allows for different shapes whether they by ideal or non-ideal. And, from this, Examiner stated that there is no evidence the prior art device will act differently from the claimed device as it appears the only difference between the claimed device and the prior art device was different shapes of the gates and/or inter-gate oxide.
Based upon the above, Applicant’s arguments are not persuasive.
Conclusion
THIS ACTION IS MADE FINAL. 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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/VINCENT WALL/Primary Examiner, Art Unit 2898
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