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 .
DETAILED ACTION
Applicants’ response of 04/30/2026 has been entered in the record and considered. With respect to the rejection claims 35 USC 103 (a) is withdrawn in view of applicants’ amendments. The following new rejection to claims 1-3 is made under 35 USC 103. Claims 1-3 are under consideration. Claims 1-3 are rejected.
Continued Examination Under 37 CFR 1.114 after Final Rejection
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 04/30/2026 has been entered.
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 1-3 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.
Claim 1 recites in lines 8-12:
“the cathode electrode is in direct contact with the N layer across the entire surface on the other side of the semiconductor substrate,”
and subsequently recites:
“wherein the entire surface between the cathode electrode and the N layer are Schottky-junctioned.”
It is unclear what particular surface is encompassed by “the entire surface.” The claim previously introduces “a surface on the other side of the semiconductor substrate” in connection with the location at which the cathode electrode is formed. However, the subsequently recited “entire surface” is not expressly identified as:
1. the entire surface of the semiconductor substrate on the cathode-electrode side;
2. the entire surface of the N layer;
3. the entire surface of the cathode electrode facing the N layer; or
4. the entire interface formed between the cathode electrode and the N layer.
These interpretations do not necessarily define the same structural relationship or scope. For example, the cathode electrode could contact an entire exposed portion of the N layer without covering the entire surface of the semiconductor substrate, or the cathode electrode could cover the entire substrate surface while contacting only a portion of the N layer.
The subsequent phrase “the entire surface between the cathode electrode and the N layer” does not resolve the ambiguity because it is unclear whether this phrase refers back to the previously recited surface on the other side of the semiconductor substrate or introduces a different surface or interface. Furthermore, because the claim does not clearly identify the relevant surface, it is unclear whether the entire substrate-side surface, the entire N-layer surface, the entire electrode surface, or only the interface between the cathode electrode and the N layer must form the recited Schottky junction.
Accordingly, one of ordinary skill in the art would not be reasonably apprised of the metes and bounds of the required direct-contact and Schottky-junction relationships.
Applicant is required to amend the claim or explain, with reference to the specification, which particular surface is intended by these limitations.
Claim Interpretation:
For purposes of examination, the Examiner interprets the disputed limitations as requiring that the cathode electrode directly contact the N layer over the entire cathode-side interface between those elements and that the entirety of that interface form a Schottky junction. This interpretation appears most consistent with the claim language considered as a whole and the disclosure of the application.
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.
Claims 1-2 are rejected under 35 U.S.C. 103 as being unpatentable over US Pub # 2014/0061875 to Ogura et al.
Regarding independent claim 1, Ogura discloses a semiconductor device (Fig. 10: 101) comprising:
a semiconductor substrate (10);
an anode electrode (16), formed on a surface on one side of the semiconductor substrate (10);
a cathode electrode (11), formed on a surface on the other side of the semiconductor substrate (10);
a P layer (15), formed on the anode electrode side (16) in the semiconductor substrate (10); and
an N layer (92), formed on the cathode electrode side (11) in the semiconductor substrate (10) and on the other side of the P layer (15),
Specifically, Ogura discloses that n+ cathode layer (92) is disposed on cathode electrode (11), n-base layer (14) is disposed on n+ cathode layer (92), and p+ anode layer (15) is disposed on the opposite side of n-base layer (14) (see ¶0104-0106). As illustrated in Figure 10, cathode electrode (11) continuously extends across and directly contacts the corresponding surface of n+ cathode layer 92. Accordingly, Figure 10 teaches the claimed arrangement in which the cathode electrode is in direct contact with an N layer across an entire surface on the cathode-electrode side of the semiconductor substrate.
Ogura’s Figure 10 embodiment does not expressly state that the entire interface between cathode electrode 11 and n+ cathode layer 92 forms a Schottky junction.
However, Ogura further teaches forming a Schottky contact between cathode electrode (11) and an N-type cathode layer (13) (see Figure 25A and ¶021-0216). Ogura explains that the Schottky contact serves as an energy barrier that restricts electrons from flowing from N cathode layer 13 toward cathode electrode 11 immediately after recovery. Ogura further explains that adjustment of the energy barrier controls carrier reinjection and the OFF-time characteristics of the semiconductor device (see ¶0216-0219).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to configure the continuous interface between cathode electrode (11) and the N-type cathode layer of the (Figure 10 embodiment) as the Schottky interface taught in connection with (Figure 25A). One of ordinary skill would have been motivated to make this modification to provide an energy barrier uniformly across the cathode-side interface, thereby restricting electron movement toward cathode electrode (11) and controlling carrier injection and recovery characteristics in the manner expressly described by Ogura.
The modification would have amounted to applying Ogura’s known cathode-side Schottky-contact arrangement to Ogura’s continuous cathode-electrode/N-layer interface to obtain the predictable result of a continuous Schottky barrier across that interface. As modified, cathode electrode (11) would directly contact the N layer across an entire surface on the other side of semiconductor substrate (10), and the entire interface between cathode electrode (11) and the N layer would form a Schottky junction.
Ogura additionally discloses that cathode electrode (11) includes a metal such as aluminum (see ¶ 50).
Ogura further discloses an N-layer carrier concentration of not more than 3 x 1017 cm-3 (see ¶0058). This concentration overlaps the claimed range of 1 x 1012 to 1 x 1018cm-3. Accordingly, the claimed carrier-concentration range would have been prima facie obvious because the prior-art range overlaps the claimed range.
It would additionally have been obvious to select the carrier concentration within the overlapping range through routine experimentation to obtain the desired balance among Schottky-barrier characteristics, carrier injection, and device recovery performance, particularly because Ogura recognizes carrier concentration as a result-effective device parameter. Applicant’s specification does not appear to establish that the claimed range produces a critical or unexpected result throughout its full breadth.
Regarding the claimed cathode-electrode work function of 4.2 eV to 4.3 eV, Ogura discloses aluminum as a suitable cathode-electrode metal (see ¶0050). It would have been obvious to select or configure the disclosed metal electrode to have a work function within the claimed range because the work function of the cathode metal determines the energy-barrier characteristics of the disclosed metal/N-type semiconductor Schottky junction. Selection of the metal work function within a suitable range would have been a result-effective-variable optimization to obtain the desired Schottky barrier and carrier-control characteristics described by Ogura.
Regarding claim 2, Ogura discloses wherein the metal of the cathode electrode (11) comprises aluminum or an aluminum-silicon alloy as a main component (¶0050).
Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over US Pub # 2014/0061875 to Ogura et al. in view of US Pub # 2003/0218230 to Takahashi et al.
Regarding claim 3, Ogura discloses wherein the semiconductor substrate (10) includes a semiconductor layer 14 which the semiconductor layer 14 includes silicon (¶0060). Ogura fails to explicitly disclose wherein the semiconductor substrate comprises a silicon wafer.
Takahashi teaches it was known in the art to use silicon wafer for a semiconductor substrate (¶0044 and Fig. 3) and it would have been obvious to one of ordinary skill in the art at the time of the invention to have selected silicon wafer for the undisclosed semiconductor substrate as mere selection of an art recognized semiconductor substrate suitable for the intended use of Takahashi (MPEP §2144.07).
Response to Arguments
Applicant's arguments, see (pages 1-6), filed 04/30/2026, with respect to the rejection of claim(s) 1-3 under 35 USC 103(a) have been fully considered but are moot because the arguments do not apply to the combination of embodiments being used in the current rejection.
Applicant’s argument 1:
Applicant argues that Ogura does not disclose:
“the cathode electrode is in direct contact with the N layer across the entire surface on the other side of the semiconductor substrate,” and “the entire surface between the cathode electrode and the N layer are Schottky-junctioned.”
Examiner’s response:
Applicant’s argument is persuasive only with respect to Ogura’s Figure 1A considered by itself.
Figure 1A includes a mixed cathode-side interface. Cathode electrode 11 forms:
• An ohmic contact with n+ cathode layers 12; and
• A Schottky contact with portions 13b of N cathode layer 13.
Therefore, Figure 1A alone does not expressly disclose a Schottky junction across the entire cathode electrode/N-layer interface.
However, the present rejection does not rely on Figure 1A alone. The rejection relies on the combined teachings of Ogura’s Figure 10 and Figure 25A.
Applicant’s argument 2”
Applicant argues that Ogura’s cathode-side surface requires both n+ cathode layer 12 and N cathode layer 13b. Therefore, applicant argues that Ogura does not teach a cathode electrode directly contacting only one N layer across the entire surface.
Examiner’s response:
This argument is not persuasive because Ogura does not require the mixed arrangement of layers 12 and 13b in every embodiment.
Figure 10 and ¶0103-0106 disclose an alternative configuration in which cathode electrode 11 continuously contacts n+ cathode layer 92. Unlike Figure 1A, Figure 10 does not contain alternating n+ layers 12 and exposed N-layer portions 13b at the cathode interface.
Accordingly, Figure 10 teaches a continuous cathode electrode/N-layer interface across the cathode side of the semiconductor device.
Figure 10 does not expressly state that the continuous interface is Schottky-junctioned. Ogura’s Figure 25A teaching is relied upon for that feature.
Applicant’s argument 3:
Applicant argues that Ogura does not teach that the entire interface between the cathode electrode and the N layer is Schottky-junctioned.
Examiner’s response:
Ogura’s Figure 25A and ¶0216 expressly disclose a Schottky contact between cathode electrode 11 and N cathode layer 13.
¶0216 explains that the Schottky contact serves as an energy barrier that restricts electrons from flowing from N cathode layer 13 toward cathode electrode 11 immediately after recovery.
¶0219 further explains that the Schottky energy barrier affects carrier reinjection and permits adjustment of carrier injection and OFF-time characteristics.
It would have been obvious to one of ordinary skill in the art to apply Ogura’s Schottky-contact teaching from Figure 25A to the continuous cathode electrode/N-layer interface shown in Figure 10. The reason for doing so would have been to provide Ogura’s disclosed energy barrier continuously across the cathode interface, thereby controlling and suppressing electron injection over the interface.
As modified, the entire interface between cathode electrode 11 and the N layer would form a Schottky junction.
Applicant’s argument 4:
Applicant argues that modifying Ogura to provide a Schottky junction across the entire surface would destroy Ogura’s core design and principle of operation because Ogura requires both the n+ ohmic-contact regions and the N-layer Schottky-contact regions.
Examiner’s response:
This argument is not persuasive because the proposed modification does not begin with the mixed structure of Figure 1A. Instead, the proposed modification begins with the continuous cathode-side structure of Figure 10.
Figure 10 demonstrates that Ogura does not require the mixed arrangement of n+ layer 12 and N-layer portion 13b in every disclosed configuration. Figure 10 already provides a continuous N-type cathode layer contacting cathode electrode 11.
The proposed modification merely applies Ogura’s disclosed Schottky-contact relationship to that continuous interface. The resulting device would continue to function as a semiconductor diode and would continue to control carrier movement and recovery behavior.
Therefore, the modification would not render Ogura inoperable or fundamentally change its principle of operation. Instead, it would use Ogura’s disclosed Schottky-barrier mechanism over a larger portion of the cathode interface.
Applicant’s argument 5:
Applicant argues that, in Ogura, electron injection varies according to location because Figure 1A includes both ohmic and Schottky contacts. Applicant states that this produces a nonuniform electron distribution and potentially weakens the breakdown voltage during turn-off.
Examiner’s response:
This argument distinguishes the particular mixed-contact configuration of Figure 1A, but it does not distinguish the proposed combination of Figures 10 and 25A.
Figure 10 provides the continuous interface, and Figure 25A teaches using a Schottky contact to suppress electron movement. Applying the Schottky contact continuously across the Figure 10 interface would avoid the alternating ohmic/Schottky contact arrangement relied upon in applicant’s argument.
Furthermore, amended claim 1 does not recite:
• A uniform electron distribution;
• A particular breakdown voltage;
• A particular recovery-loss value; or
• A specified degree of improved performance.
Those unclaimed results do not provide a structural distinction over the proposed combination.
Applicant’s argument 6:
Applicant argues that the claimed full-surface Schottky junction provides the following technical effects:
• Controlling the quantity of electrons injected from the cathode side;
• Suppressing recovery loss; and
• Maintaining a relatively small forward-voltage drop.
Examiner’s response:
These arguments have been considered but are not persuasive.
Ogura expressly teaches that its cathode-side Schottky contact creates an energy barrier that suppresses electron movement and controls carrier injection and recovery behavior (see ¶0216-0219. Therefore, controlling electron injection and suppressing recovery effects would have been predictable results of extending Ogura’s disclosed Schottky contact across the continuous interface shown in Figure 10.
Additionally, claim 1 does not recite numerical limitations concerning recovery loss, forward-voltage drop, or electron-injection uniformity. Applicant has also not provided comparative evidence demonstrating that the claimed structure produces unexpected results relative to Ogura.
Applicant’s argument 7:
Applicant argues that Ogura teaches away from the claimed full-surface Schottky junction.
Examiner’s response:
Applicant has not identified any statement in Ogura that criticizes, discredits, or discourages forming a continuous cathode-side Schottky interface.
Ogura’s disclosure that one embodiment uses both ohmic and Schottky-contact regions does not establish that Ogura teaches away from using a greater Schottky-contact area. Rather, Ogura positively teaches that a cathode-side Schottky contact provides an energy barrier that suppresses electron movement and permits adjustment of carrier injection.
Accordingly, Ogura would have suggested using an increased Schottky-contact area when greater suppression of cathode-side electron injection was desired.
Applicant’s argument 8:
Applicant argues that Takahashi does not cure the deficiencies of Ogura.
Examiner’s response:
Takahashi is not relied upon to teach the amended full-surface Schottky-junction limitation of claim 1.
The amended limitation is addressed by combining Ogura’s Figure 10 continuous-interface structure with Ogura’s Figure 25A Schottky-contact teaching.
Takahashi is relied upon only for the additional limitation of dependent claim 3. Therefore, applicant’s argument that Takahashi does not cure the alleged deficiency of claim 1 is not responsive to the rejection presently made.
Applicant’s argument 9:
Applicant argues that dependent claims 2 and 3 are patentable because they depend from claim 1.
Examiner’s response:
Because applicant’s arguments do not overcome the revised rejection of independent claim 1, the dependency of claims 2 and 3 does not establish their patentability.
The additional limitations of claims 2 and 3 are addressed separately in their respective rejections.
Applicant’s arguments are persuasive only to the extent that Ogura’s Figure 1A, considered individually, does not expressly disclose a Schottky junction across the entire cathode electrode/N-layer interface. However, the present rejection relies on the continuous cathode electrode/N-layer interface taught by Ogura’s Figure 10 in combination with the cathode-side Schottky-contact teaching of Ogura’s Figure 25A. For the reasons discussed above, the combined teachings would have rendered amended claim 1 obvious to one of ordinary skill in the art before the effective filing date of the claimed invention. Therefore, the rejection of claim 1 under 35 U.S.C. 103 is maintained as modified.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MOHSEN AHMADI whose telephone number is (571)272-5062. The examiner can normally be reached M-F: 9:00am-5:00pm.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, William F Kraig can be reached at 571-272-8660. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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.
/MOHSEN AHMADI/Primary Examiner, Art Unit 2896
Prosecution Insights