Attorney Docket Number: 01_4342
Filing Date: 11/30/2023
Claimed Foreign Priority Date: 01/13/2023 (JP2023-003853)
Inventor: Noborio
Examiner: Thomas McCoy
DETAILED ACTION
This Office action responds to the amendment filed 4/17/2026.
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 to 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 a 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.
Acknowledgement
The Amendment filed on 4/17/2026, responding to the Office action mailed 3/04/2026, has been entered. Applicant amended claim 1 and added claims 4-9. The present Office action is made with all the suggested amendments being fully considered.
Response to Amendments
Applicant’s amendments to the claims have overcome the respective claim objections and claim rejections under 35 U.S.C. 103, as previously formulated in the Non-Final Office action mailed on 3/04/2025. Accordingly, the claim objections and claim rejections of 35 U.S.C. 103 are hereby withdrawn. Accordingly, pending in this application are claims 1-9. New grounds of rejections are presented below, however, as necessitated by applicant’s amendments to the claims.
Claim Interpretation
Claim 1 reads “…a plurality of trench gate structures, each of which has a trench extending…” which will be interpreted as “… a plurality of trench gate structures, wherein each trench gate structure has a trench extending…”.
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.
Claims 1-9 are rejected under 35 U.S.C. 103 as being unpatentable over Naito (US 20180082996 A1) in view of Kachi (US 20180019160 A1) further in view of Imam (US 20040217418 A1).
Regarding claim 1, Naito (see, e.g., fig. 3) shows most aspects of the instant invention including a semiconductor device comprising:
A drift layer (e.g., drift region 18) having a first conductivity type (see, e.g., paragraph 74 “…(N-)-type drift region 18 …”);
A base layer (e.g., base region 14) having a second conductivity type (see, e.g., fig. 3 or paragraph 73 “A (P-)-type base region 14 is formed...”);
An impurity layer (e.g., buffer region 20) of the first conductivity type (e.g., (N-)-type, see fig. 3) formed opposite to the base layer (e.g., base region 14) relative to the drift layer (e.g., drift region 18);
A plurality of trench gate structures (e.g., plurality of trench gate portions 40 + dummy trench portions 30), wherein each trench gate structure (e.g., individual trench gate portion 40) has a trench (see, e.g., trench configuration of trench gate portion 40/30 within fig. 3) extending through the base layer (e.g., base region 14) and having a longitudinal direction (e.g., vertical direction of fig. 3) crossing a stacking direction of the drift layer (e.g., drift region 18) and the base layer (e.g., base region 14), a gate insulating film (e.g., insulating films 42 and 32) formed on a wall surface of the trench, and a gate electrode (e.g., gate conductive portions 44 and 34) formed on the gate insulating film (e.g., insulating films 42 and 32);
A first impurity region (e.g., emitter 12) of the first conductivity type (see, e.g., paragraph 59 “…the emitter region 12 is of (N+)-type”) formed on a surface layer portion of the base layer (e.g., base region 14) and having an impurity concentration higher (see, e.g., paragraph 17 “The semiconductor device may further include a drift region which is provided below the base region and has a lower impurity concentration than the emitter region”) than that of the drift layer (e.g., drift region 18);
A second impurity region (e.g., contact region 15 (see fig. 1, noting fig. 3 is a cross section of fig. 1)) of the second conductivity type (see, e.g., paragraph 59 “In the present example, the contact region 15 is of (P+)-type”) formed on a surface layer portion of the base layer (e.g., base region 14) and having an impurity concentration higher (see, e.g., paragraph 59 “The contact region 15, which is of the second conductivity type and has a higher impurity concentration than the base region 14, is formed in the front surface of the base region 14…”);
A first electrode (e.g., emitter electrode 52) electrically connected (see, e.g., paragraph 61 “The emitter electrode 52 is connected to the emitter region 12 and the contact region 15…”) to the first impurity region (e.g., emitter 12) and the second impurity region (e.g., contact region 15);
A second electrode (e.g., collector electrode 24) electrically connected to the impurity layer (e.g., buffer region 20);
The first impurity region (e.g., emitter 12) and the second impurity region (e.g., contact region 15) are alternately formed along the longitudinal direction of the trench (see, e.g., figs 1 or 2, noting that fig. 3 and fig. 2 are cross sections of fig. 1);
The second impurity region (e.g., contact region 15), which is viewed in the stacking direction of the drift layer (e.g., drift region 18) and the base layer (e.g., base region 14), has a first contact side (see, e.g., annotated fig. 1 or fig. 2 of Naito) in contact with a first trench (e.g., left-side trench structure 40) in a lateral direction intersecting the longitudinal direction (e.g., vertical direction), the first contact side (see, e.g., annotated fig. 1) having a predetermined length and two boundaries (e.g., left-side top and bottom contact points), and a second contact side (see, e.g., annotated fig. 1) in contact with a second trench (e.g., right-side dummy trench structure 30) adjacent to the first trench (e.g., left-side trench structure 40) in the lateral direction, the second contact side (see, e.g., annotated fig. 1) having a predetermined length and two boundaries (e.g., right-side top and bottom contact points).
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Annotated Fig. 1
Naito (see, e.g., fig. 3), however, fails to show a first linear portion is defined to extend from one of the boundaries of the first contact side toward the second trench, a second linear portion is defined to extend from the other of the boundaries of the first contact side toward the second trench, a third linear portion is defined to extend from one of the boundaries of the second contact side toward the first trench, a fourth linear portion is defined to extend from the other of the boundaries of the second contact side toward the first trench, one of a first angle between the first trench and the first linear portion and a second angle between the first trench and the second linear portion is less than 90° and the other angle is less than or equal to 90°, and one of a third angle between the second trench and the third linear portion and a fourth angle between the second trench and the fourth linear portion is less than 90°, and the other angle is less than or equal to 90° and one of the first angle, the second angle, the third angle and the fourth angle is different from at least another one of the first angle, the second angle, the third angle and the fourth angle.
Kachi (see, e.g., fig. 37), in a similar device to Naito, teaches an impurity region (e.g., p-type region SJ2) has a first linear portion (see, e.g., annotated fig. 2) that is defined to extend from one of the boundaries of a first contact side (see, e.g., annotated fig. 2) toward a second trench (see, e.g., annotated fig. 2), a second linear portion (see, e.g., annotated fig. 2) is defined to extend from the other of the boundaries (e.g., bottom left boundary of relevant n-type source region in annotated fig. 2) of the first contact side (see, e.g., annotated fig. 2) toward the second trench (see, e.g., annotated fig. 2), a third linear portion (see, e.g., annotated fig. 2) is defined to extend from the other of the boundaries of the second contact side (see, e.g., annotated fig. 2) toward the first trench (see, e.g., annotated fig. 2), a fourth linear portion (see, e.g., annotated fig. 2) is defined to extend from the other of the boundaries of the second contact side (see, e.g., annotated fig. 2) toward the first trench (see, e.g., annotated fig. 2), one of a first angle between the first trench (see, e.g., annotated fig. 2) and the first linear portion (see, e.g., annotated fig. 2) and a second angle between the first trench (see, e.g., annotated fig. 2) and the second linear portion (see, e.g., annotated fig. 2) is less than 90° (see, e.g., annotated fig. 3 – note that the angle is substantially more acute than a right-angle) and the other angle is less than or equal to 90° (note that angle between linear portion and trench is substantially acute, thus less than 90° (and note the structure is structurally symmetrical, thus the angles on the other side are identical)), and one of a third angle between the second trench (see, e.g., annotated fig. 3) and the third linear portion (see, e.g., annotated fig. 2) and a fourth angle between the second trench (see, e.g., annotated fig. 2) and the fourth linear portion (see, e.g., annotated fig. 2) is less than 90° (see, e.g., annotated fig. 3 – note that the angle is substantially more acute than a right-angle) and the other angle is less than or equal to 90° (note that angle between linear portion and trench is substantially acute, thus less than 90° (and note the structure is structurally symmetrical, thus the angles on the other side are identical)).
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Annotated Fig. 2
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Annotated Fig. 3
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the impurity region geometry configuration of Kachi within the impurity regions of Naito, in order to optimize performance and space, and increase the total contact area of the impurity region away from the interface, expanding the amount of area available for current flow in the center of the region between trenches.
Naito in view of Kachi, however, fails to teach one of the first angle, the second angle, the third angle and the fourth angle is different from at least another one of the first angle, the second angle, the third angle and the fourth angle.
Imam (see, e.g., fig. 9), in a similar device to Naito in view of Kachi, teaches one of a first angle (e.g., 1st angle of annotated fig. 4 below), a second angle (e.g., 2nd angle of annotated fig. 4 below), a third angle (e.g., 3rd angle of annotated fig. 4 below), and a fourth angle (e.g., 4th angle of annotated fig. 4) is different from at least another one of the first angle (e.g., 1st angle of annotated fig. 4 below), the second angle (e.g., 2nd angle of annotated fig. 4 below), the third angle (e.g., 3rd angle of annotated fig. 4 below), and the fourth angle (e.g., 4th angle of annotated fig. 4) within a contact region (e.g., pentagon contact 49).
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Annotated Fig. 4
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the asymmetrical angle configuration/shortened contact dynamic of Imam within the contact region and trench/channel boundaries of Naito in view of Kachi, in order to reduce the contact length along the trench, reducing the resistance within the device (see, e.g., paragraphs 2-4 or 18 of Imam). Also note that this shortening of the contact side would result in a slight change of angle for the body contact to extend in a new angle on the top or bottom end in order to maintain the general size of the contact region (i.e., protrude at a slightly different angle so as to reach the same location where the lower portion of the contact is disposed) as shown in Naito in view of Kachi. In addition, it also would have been obvious at the time of filing the invention to slightly modify the shape or exact protrusion angle to satisfy various connective or space requirements as desired, and a change in shape is generally recognized as being within the level of ordinary skill in the art. In re Dailey, 357 F.2d 669, 149 USPQ 47 (CCPA 1966).
Regarding claim 2, Imam (see, e.g., fig. 9) teaches a collection of a first, second, third, and fourth angle (see, e.g., annotated fig. 3) that can be defined as θ1, θ2, θ3, and θ4 respectively, which satisfies a formula of (1/tanθ1 + 1/tanθ2) = (1/tanθ3 + 1/tanθ4) (e.g., note that the first and third angles are equivalent, and the second and fourth angles are equivalent– and (1/x + 1/y) = (1/x + 1/y)).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the asymmetric layout of Imam (thus providing equivalent angles between the trenches and impurity linear portions) within the layout of Naito in view of Kachi further in view of Imam, in order to provide a shortened contact length between the contact region and trench and reduce the resistance within the device. See also the comments above with respect to claim 1, which are considered to be relevant here.
Regarding claim 3, Imam (see, e.g., fig. 9) teaches wherein one of the first angle (see, e.g., 1st angle in annotated fig. 4) and the second angle (see, e.g., 2nd angle in annotated fig. 4) is equal to one of the third angle (see, e.g., 3rd angle in annotated fig. 3) and the fourth angle (see, e.g., 4th angle in annotated fig. 3).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the angular setup of Imam within the configuration of Naito in view of Kachi further in view of Imam for the reasons listed above, which are considered to be relevant here (see, e.g., paragraphs 7-10 regarding claims 2-3).
Regarding claim 4, Imam (see, e.g., fig. 9) teaches wherein two of the first angle (e.g., 1st angle of annotated fig. 4), the second angle (e.g., 2nd angle of annotated fig. 4), the third angle (e.g., 3rd angle of annotated fig. 4 below), and the fourth angle (e.g., 4th angle of annotated fig. 4) are equal to each other (e.g., note the 1st and 3rd angle are equivalent to one another) and are not equal to the other two of the first angle (e.g., 1st angle of annotated fig. 4), the second angle (e.g., 2nd angle of annotated fig. 4), the third angle (e.g., 3rd angle of annotated fig. 4), and the fourth angle (e.g., 4th angle of annotated fig. 4).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the asymmetric layout of Imam (thus providing equivalent angles between the trenches and impurity linear portions) within the layout of Naito in view of Kachi further in view of Imam, in order to provide a shortened contact length between the contact region and trench and reduce the resistance within the device. See also the comments above with respect to claims 1-3, which are considered to be relevant here.
Regarding claim 5, Imam (see, e.g., fig. 9) teaches wherein the other two (e.g., the 2nd angle of annotated fig. 4 and the 4th angle of annotated fig. 4) of the first angle (e.g., 1st angle of annotated fig. 4), the second angle (e.g., 2nd angle of annotated fig. 4), the third angle (e.g., 3rd angle of annotated fig. 4), and the fourth angle (e.g., 4th angle of annotated fig. 4) are equal to each other (see, e.g., annotated fig. 4).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the asymmetric layout of Imam (thus providing equivalent angles between the trenches and impurity linear portions) within the layout of Naito in view of Kachi further in view of Imam, in order to provide a shortened contact length between the contact region and trench and reduce the resistance within the device. See also the comments above with respect to claims 1-3, which are considered to be relevant here.
Regarding claim 6, Imam (see, e.g., fig. 9), in an alternate embodiment (see, e.g., body contact 47 of fig. 9), teaches wherein a second angle and a fourth angle are 90° (see, e.g., annotated fig. 5 below).
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Annotated Fig. 5
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the 90 degree configuration of Imam between the second and fourth angle of Naito in view of Kachi further in view of Imam, in order to achieve the expected result of providing a direct and linear connection between the two trenches, shortening the required material on one side of the contact region to connect the two trenches and to reduce the cost of material during manufacturing/fabrication of the device.
Regarding claim 7, Naito (see, e.g., fig. 3) shows wherein the first contact side (see, e.g., annotated fig. 1 or fig. 2 of Naito) is in direct contact with the first trench (e.g., left-side trench structure 40) and the second contact side (see, e.g., annotated fig. 1) is in direct contact with the second trench (e.g., right-side dummy trench structure 30).
Regarding claim 8, Kachi (see, e.g., fig. 37) teaches wherein the impurity region (e.g., p-type region SJ2) further includes: a fifth linear portion (e.g., fifth linear portion of annotated fig. 6 below) connecting the first linear portion (e.g., first linear portion of annotated fig. 2) and the third linear portion (e.g., third linear portion of annotated fig. 2), and a sixth linear portion (e.g., sixth linear portion of annotated fig. 6 below) connecting the second linear portion (e.g., second linear portion of annotated fig. 2) and the fourth linear portion (e.g., fourth linear portion of annotated fig. 2), the fifth linear portion (e.g., fifth linear portion of annotated fig. 6 below) is not parallel to either of the first linear portion (e.g., first linear portion of annotated fig. 2) and the third linear portion (e.g., third linear portion of annotated fig. 2), the sixth linear portion (e.g., sixth linear portion of annotated fig. 6 below) is not parallel to either of the second linear portion (e.g., second linear portion of annotated fig. 2) and the fourth linear portion (e.g., fourth linear portion of annotated fig. 2).
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Annotated fig. 6
Accordingly, it would have been obvious to one ordinary skill in the art at the time of filing the invention to include the fifth linear portions and sixth linear portions of Kachi within the contact region of Naito in view of Kachi further in view of Imam, in order to achieve the expected result of increasing the total contact area of the impurity region away from the interface, expanding the amount of area available for current flow in the center of the region between trenches. Also see the comments with respect to claim 1, which are considered to be relevant here.
Regarding claim 9, Kachi (see, e.g., fig. 37), teaches wherein the impurity region (e.g., p-type region SJ2) has an octagonal planar shape (see, e.g., annotated fig. 7 below, note the 8 sides, hence an octagonal shape).
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Annotated Fig. 7
Accordingly, it would have been obvious to one ordinary skill in the art at the time of filing the invention to include the fifth linear portions and sixth linear portions of Kachi within the contact region of Naito in view of Kachi further in view of Imam, in order to achieve the expected result of increasing the total contact area of the impurity region away from the interface, expanding the amount of area available for current flow in the center of the region between trenches. Also see the comments with respect to claim 1, which are considered to be relevant here.
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.
Any inquiry concerning this communication or earlier communications from the examiner
should be directed to Thomas McCoy at (571) 272-0282 and between the hours of 9:30 AM to 6:30 PM
(Eastern Standard Time) Monday through Friday or by e-mail via Thomas.McCoy@uspto.gov. If attempts
to reach the examiner by telephone are unsuccessful, the examiner's supervisor, Wael Fahmy, can be
reached on (571) 272-1705. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/THOMAS WILSON MCCOY/ Examiner, Art Unit 2814 /WAEL M FAHMY/Supervisory Patent Examiner, Art Unit 2814
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