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 .
This office action is in response to application filed on 07/16/2024.
Currently claims 1-15 are pending in the application.
Information Disclosure Statement
The information disclosure statements (IDS) submitted on 07/16/2024 and 01/22/2025 were filed before the mailing date of the office action. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statements were considered by the examiner.
Claim Rejections - 35 USC § 112 (b)
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 2-15 are rejected under 35 U.S.C. 112 (b), as being indefinite for failing to particularly pointing out and distinctly claim the subject matter which the inventor or a joint inventor, regard as their invention.
Regarding claim 2, the claim recites that the first transition layer's thickness is “larger than 0 microns and less than or equal to 2 microns” (a fully bounded range), but recites the second transition layer's thickness merely as “being ranged from less than or equal to 9 microns,” with no corresponding lower bound. Read literally, this permits a thickness approaching or including zero, which is inconsistent with the requirement that “a second transition layer” actually exists “connected under the first transition layer.” The absence of a lower bound — in a claim that otherwise carefully bounds every other thickness and doping parameter — renders the metes and bounds of this limitation unclear. Clarification (e.g., “larger than 0 microns and less than or equal to 9 microns”) is required.
Regarding claims 5–14 — the claims lack Antecedent Basis for “the first transition layer” / “the second transition layer”. Claim 1 recites only a single, undivided “a transition layer of the first doping type, connected under the pillar region.” The distinct terms “a first transition layer” and “a second transition layer” are introduced for the first time in claim 2, which depends from claim 1 and expressly recites that “the transition layer comprises” these two named sub-layers.
Claims 5 and 7 each depend directly from claim 1 (not claim 2), yet each recites “the first transition layer” and/or “the second transition layer” as though already introduced:
Claim 5 depends from claim 1 and recites a field-stop layer whose doping “is larger than the doping concentration of the first transition layer and the second transition layer” — terms with no antecedent basis in claim 1.
Claim 7 depends from claim 1 and recites “a thickness and an energy band of the second transition layer” — again lacking antecedent basis, since claim 1 has no “second transition layer.”
Claim 14 depends from claim 1 and recites “the doping concentration ND of the first transition layer and the thickness H1 of the first transition layer” — the same defect.
Because claim 6 depends from claim 5, and claims 8–13 depend (directly or through the chain) from claim 7, the indefiniteness of claims 5 and 7 propagates to claims 6 and 8–13 as well. In total, claims 5, 6, and 7–14 are indefinite for lack of antecedent basis. This defect appears to be a drafting error — claims 5, 7, and 14 were most likely intended to depend from claim 2 (which properly introduces the first/second transition layer terminology) rather than from claim 1. Correction of the claim dependency (i.e., amending claims 5, 7, and 14 to depend from claim 2) would resolve this rejection as to antecedent basis, though the further issues might remain.
Furthermore, regarding claims 7 and 15 — “Precisely Controlled” Is an unbounded term of degree - Claims 7 and 15 each recite that “excess carriers of the second transition layer are precisely controlled to suppress a tail current.” “Precisely controlled” is a relative, subjective term of degree. Absent an objective standard recited in the claim (or an accepted standard in the art for what quantum of control qualifies as “precise”), a person of ordinary skill cannot determine the scope of claims 7 and 15 with reasonable certainty. Clarification and/or correction are/is required.
Furthermore, regarding claim 9 — Indefinite hybrid apparatus/process claim - Claim 9 (an apparatus/device claim, per the preamble of claim 1) purports to define the claimed device's second transition layer by reference to an iterative simulation methodology performed not on the claimed device itself, but on a separately defined, structurally identical “design-fundamental IGBT device” comparator “in which excess carriers of the second transition layer are not controlled.” The claim recites an open-ended iterative loop (“if within the predetermined control range... if it is not within the predetermined control range, jumping to the step of assigning value... until the assigned value... is found”) whose numeric “predetermined control range” is left undefined in claim 9 itself (it is defined only in dependent claim 10, as 20%–50%). As drafted, it is unclear (i) whether the metes and bounds of the claimed device turn on whether this simulation was actually performed by a practitioner or manufacturer, (ii) how a court or examiner would assess infringement/anticipation against a physical device without independently running the recited simulation, and (iii) what structural feature of the claimed device actually results from this process, as opposed to the comparator device. This mixture of process steps performed on an uncleaned, extraneous comparator device to derive a design parameter for the claimed apparatus renders the scope of claim 9 indefinite.
Furthermore, regarding claim 13 - Claim 13 recites that “when the average value of [the EFp−EV term] ... is 0.258 eV, the second transition layer is less than or equal to 9 microns.” The claim recites a single fixed value (0.258 eV) rather than a range for a continuously variable physical parameter, without any indication of tolerance (e.g., “about”), which is unusual for a manufactured device and raises questions as to whether any literal device could ever satisfy this precise condition. Clarification is required.
Claims 3-4 and 8-13 are also rejected due to their dependence on a rejected base claim.
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 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 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:
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 1 is rejected under 35 U.S.C. 103 as being unpatentable over US 2023/0155014 A1 (Wu) and further in view of US 2020/0105874 A1 (Yilmaz).
Regarding claim 1, Wu discloses, an Insulated Gate Bipolar Transistor (IGBT) device, comprising:
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a drift region (5; first N-type epitaxial layer; Fig. 3; [0039]) of a first doping type (n-type);
a plurality of pillar regions (101; P column; Fig. 3; [0041]) of a second doping type (p-type), disposed at intervals in a lateral direction within the drift region (5); and
a transition layer (4; N-type FS isolating layer; Fig. 3; [0038]) of the first doping type (n-type), connected under the pillar region (101);
But Wu fails to teach explicitly, wherein a thickness of the transition layer is larger than 2 microns and less than or equal to 11 microns, and a doping concentration of the transition layer ranges from larger than or equal to 2.4x1014/cm3 to less than or equal to 2.4x1016/cm3.
However, in analogous art, Yilmaz discloses, wherein a thickness of the transition layer (124; transition layer; Fig. 1A; [0039]) is larger than 2 microns and less than or equal to 11 microns (Yilmaz teaches 2um to 5um; [0039]) , and a doping concentration of the transition layer ranges from larger than or equal to 2.4x1014/cm3 to less than or equal to 2.4x1016/cm3 (Yilmaz teaches 5x1014/cm3 to to 5x1015/cm3) (Fig. 1A; [0039]). In MPEP 2144.05 (I), it is stated that In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use the above claimed ranges since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or working range involves only routine skill in the art. In re Aller, 105 USPQ 233 (See MPEP 2144.05 (II) (A)).
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Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having the teachings of Wu and Yilmaz before him/her, to modify the teachings of an IGBT device using a transition layer as taught by Wu and to include the teachings of thickness and doping of the transition layer as taught by Yilmaz since these are essential parameters to design the transition layer and absent this important teaching in Wu, a person with ordinary skill in the art would be motivated to reach out to Yilmaz while forming an IGBT device of Wu.
Claims 2-4 are rejected under 35 U.S.C. 103 as being unpatentable over Wu and Yilmaz as applied to claim 1 and further in view of US 2019/0019879 A1 (Lee).
Regarding claim 2, the combination of Wu and Yilmaz fails to teach explicitly, the IGBT device according to claim 1, wherein the transition layer comprises:
a first transition layer connected under the pillar region, a thickness of the first transition layer being ranged from larger than 0 microns and less than or equal to 2 microns, and
a doping concentration of the first transition layer being ranged from larger than or equal to 2.4x1014/cm3 to less than or equal to 2.4x1016/cm3; and
a second transition layer connected under the first transition layer, a thickness of the second transition layer being ranged from less than or equal to 9 microns, and
a doping concentration of the second transition layer being ranged from larger than or equal to 2.4x1014/cm3 to less than or equal to 2.4x1016/cm3.
However, in analogous art, Lee discloses, splitting the same-conductivity-type buffer/field-stop region into two sub-layers (124 and 122; upper implanted FS layer and a lower implanted FS layer; Fig. 1B; [0041]).
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Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having the teachings of Wu, Yilmaz and Lee before him/her, to modify the teachings of an IGBT device using a transition layer as taught by Wu and to include the teachings of transition layer divided into two sub-layers as taught by Lee since it helps a doping-peak interface to control the field/depletion profile in the buffer region. In MPEP 2143 (I) (A), it is stated that Combining prior art elements according to known methods to yield predictable results is obvious. Absent this important teaching in Wu, a person with ordinary skill in the art would be motivated to reach out to Lee while forming an IGBT device of Wu.
The above teaching from Lee can be combined with Yilmaz which teaches the thickness of the transition layer (124; transition layer; Fig. 1A; [0039]) being larger than 2 microns and less than or equal to 11 microns (Yilmaz teaches 2um to 5um; [0039]) , and a doping concentration of the transition layer ranges from larger than or equal to 2.4x1014/cm3 to less than or equal to 2.4x1016/cm3 (Yilmaz teaches 5x1014/cm3 to to 5x1015/cm3) (Fig. 1A; [0039]). Splitting the transition layer into two sub-layers, would make each individual sub-layer lower than the single layer and as a result, the obviousness of claimed thickness and doping will still be valid using MPEP 2144.05 (I), where it is stated that In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use the above claimed ranges since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or working range involves only routine skill in the art. In re Aller, 105 USPQ 233 (See MPEP 2144.05 (II) (A)).
Regarding claim 3, the combination of Wu, Yilmaz and Lee discloses, the IGBT device according to claim 2, wherein doping concentrations of the drift region, the first transition layer, and the second transition layer are increased sequentially (Fig. 1B; [0041] – [0042]; Lee Reference).
Note: Lee teaches in para. [0041] that the thickness and impurity density of each of the at least two layers namely, the lower and upper implant FS layers 122 and 124, forming the implant FS layer 120a may vary depending on required characteristics of the power device 1000a. With this teaching from Lee, it is well within the purview of a person with ordinary skill in the art to make doping concentrations of the drift region, the first transition layer, and the second transition layer are increased sequentially.
Regarding claim 4, the combination of Wu, Yilmaz and Lee discloses, the IGBT device according to claim 2, wherein the first transition layer is evenly doped, and the second transition layer is evenly doped (Fig. 1B; [0041] – [0042]; Lee Reference).
Note: Lee teaches in para. [0041] that the thickness and impurity density of each of the at least two layers namely, the lower and upper implant FS layers 122 and 124, forming the implant FS layer 120a may vary depending on required characteristics of the power device 1000a. With this teaching from Lee, it is well within the purview of a person with ordinary skill in the art to make the first transition layer and the second transition layer evenly doped.
Allowable Subject Matter
Claims 5-6 are objected to as being dependent upon rejected base claims, but would be allowable if rewritten in independent forms including all of the limitations of the base claims and any intervening claims.
Regarding claim 5, the closest prior art, US 2023/0155014 A1 (Wu), in conjunction with US 2020/0105874 A1 (Yilmaz) and US 2019/0019879 A1 (Lee), and in combination with the other claimed features, fails to disclose, “the IGBT device according to claim 2 (corrected by Examiner), further comprising:
a field-stop layer of the first doping type, connected under the second transition layer;
wherein a doping concentration of the field-stop layer is larger than the doping concentration of the first transition layer and the second transition layer;
wherein a thickness of the field-stop layer is ranged from larger than or equal to 1 micron and less than or equal to 3 microns, and
the doping concentration of the field-stop layer is ranged from larger than or equal to 2x1015/cm3 and less than or equal to 2x1017/cm3”, in combination with the additionally claimed features, as are claimed by the Applicant.
Specifically, the aforementioned ‘the IGBT device according to claim 2 (corrected by Examiner), further comprising:
a field-stop layer of the first doping type, connected under the second transition layer;
wherein a doping concentration of the field-stop layer is larger than the doping concentration of the first transition layer and the second transition layer;
wherein a thickness of the field-stop layer is ranged from larger than or equal to 1 micron and less than or equal to 3 microns, and
the doping concentration of the field-stop layer is ranged from larger than or equal to 2x1015/cm3 and less than or equal to 2x1017/cm3,’ is material to the inventive concept of the application at hand to reduce tail current and lower turn-off loss.
Claim 6 is objected to due to its dependence on an objected base claim.
No claims are presently allowed.
Claims 7–14 (and the corresponding functional recitation of claim 15) contain patentable subject matter over the current prior art of record once:
the antecedent-basis defects are corrected (e.g., by amending claims 5, 7, and 14 to depend from claim 2);
the relative/undefined terms “precisely controlled” and “a predetermined relationship” in claims 7 and 15 are replaced with, or expressly tied to, the objective quasi-Fermi-level/energy-band equations of claims 8 and 11–13.
Examiner’s Note (Additional Prior Arts)
The examiner included a few prior arts which were not used in the rejection but are relevant to the disclosure.
US 2020/0219996 A1 (Yang) - An IGBT device is disclosed comprising a super-junction structure arranged in a drift region and formed by a plurality of N-type pillars and a plurality of P-type pillars which are alternately arrayed. Device cell structures of the IGBT device are formed in an N-type epitaxial layer at the tops of super-junction cells. Each device cell structure comprises a body region, a gate structure and a source region. N-type isolation layers having a doping concentration greater than that of the N-type epitaxial layer are formed between the bottom surfaces of the body regions and the top surfaces of the P-type pillars and are used for isolating the body regions from the P-type pillars. The super-junction structure and the N-type isolation layers can increase the current density of the device, decrease the on-state voltage drop of the device and reduce the turn-off loss of the device.
US 2019/0109131 A1 (Naito) – An IGBT device is disclosed with an accumulation layer having a function of reducing an ON voltage (Von), which is a voltage between the collector and the emitter when turning on the IGBT, by accumulating carrier. However, when turning off the IGBT, the carrier contributes to a turn-off loss (Eoff). A semiconductor device is provided, comprising: a semiconductor substrate, wherein the semiconductor substrate includes: trench portions, a mesa portion each provided between two adjacent trench portions, and a drift layer, wherein the trench portions include: a gate trench portion, and a dummy trench portion, wherein the mesa portion has: an emitter region, a contact region, and a accumulation layer, wherein the number of accumulation layers provided in a depth direction in the mesa portion adjacent to the gate trench portion is larger than that of the accumulation layers provided in the depth direction in the mesa portion between the two dummy trench portions.
US 2015/0187869 A1 (Park) - A power semiconductor device is disclosed including a first conductivity-type first semiconductor region; a resurf region disposed in the first semiconductor region and including first conductivity-type second semiconductor regions and second conductivity-type third semiconductor regions alternately disposed in a width direction; a first conductivity-type first cover region disposed in the first semiconductor region, disposed to be contiguous with an upper surface of the resurf region, and having an impurity concentration higher than that of the first semiconductor region; a second conductivity-type fourth semiconductor region disposed above the first semiconductor region; a first conductivity-type fifth semiconductor region disposed on an inner side of an upper portion of the fourth semiconductor region; and a trench gate disposed to penetrate from the fifth semiconductor region to a portion of an upper portion of the first semiconductor region and including a gate insulating layer and a conductive material.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to S M SOHEL IMTIAZ whose telephone number is (408) 918-7566. The examiner can normally be reached on 8AM-5PM, M-F, PST.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Christine S. Kim can be reached at 571-272-8458. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/S M SOHEL IMTIAZ/Primary Patent Examiner
Art Unit 2812
07/01/2026
Prosecution Insights