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 .
Response to Arguments
Applicant’s arguments, filed 03/30/2026 with respect to the rejection including claim 1 under U.S. Patent Application Publication Number 2011/0287626 A1 to Seki et al., “Seki”, in view of U.S. Patent Application Publication Number 2010/0207125 A1 to Uchida et al., “Uchida” have been fully considered and are persuasive with respect to the Uchida reference. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Seki in view of U.S. Patent Application Publication Number 2021/0328023 A1 to Rascuná et al., “Rascuná `023”, as discussed below. Since the change in rejection was not necessitated by amendment, the present office action is non-final.
Drawings
The drawings are objected to because the reference numbers embedded within dark boxes are not legible. For example, see the cover image from Applicant’s pre-grant publication US 2024/0055257:
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The text identifiers for items 10 and 20 are illegible.
Applicant’s replacement drawings submitted 03/30/2026 appear identical to originally filed drawings of 07/27/2023 and therefore the replacement drawings are not accepted since they include reference numbers embedded within dark boxes, e.g. Fig. 2:
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Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
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 1-3,10-12 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Application Publication Number 2011/0287626 A1 to Seki et al., “Seki”, in view of U.S. Patent Application Publication Number 2021/0328023 A1 to RASCUNÁ et al., “Rascuná `023”.
Regarding claim 1, Seki discloses a method for manufacturing a contact on a silicon carbide substrate, the method comprising:
providing (e.g. FIG. 3 upper image) a crystalline silicon carbide substrate (p-TYPE SILICON CARBIDE, ¶ [0004]);
forming a contact layer (“EVAPORATED MIXED FILM MADE OF TITANIUM, SILICON, AND CARBON”, Ti3SiC2, ¶ [0014],[0015],[0017],[0031]-[0034]) on the crystalline silicon carbide substrate by depositing a metallic contact material onto the surface area comprising a silicon carbide portion; and
thermal annealing (FIG. 3 “ANNEAL” ¶ [0017],[0018],[0038]) at least a part of the silicon carbide portion of the crystalline silicon carbide substrate and at least a part of the contact layer, such that a ternary metallic phase portion comprising at least the metallic contact material, silicon, and carbon is generated (Ti3SiC2).
Seki fails to clearly teach modifying a crystal structure in a surface area of the crystalline silicon carbide substrate such that a carbon-enriched silicon carbide portion is generated in the surface area.
Rascuná `023 teaches using a laser (FIG. 6 laser 80, ¶ [0038]) onto a p-type region (59’, ¶ [0035]) thereby modifying the crystal structure in a surface area such that a carbon-enriched silicon carbide portion (59’’) is generated in the surface area (“each ohmic contact 59″ has, at the surface 52a, a SiC amorphous layer where the number of carbon atoms is preponderant (for example, at least twice as high, in particular from twice to one hundred times as high) as compared to the number of silicon atoms, following upon phase separation between the silicon atoms and the carbon atoms of the SiC substrate” ¶ [0024]).
It would have been obvious before the effective filing date of the claimed invention to one having ordinary skill in the art to have performed the method of Seki by using a laser to form a carbon-enriched surface area for forming an ohmic contact as taught by Rascuná `023 in order to overcome the drawbacks (Rascuná `023 ¶ [0011]) of requiring more than one thermal-annealing steps for both activation and for the ohmic contact to occur (Rascuná `023 ¶ [0010]) and/or allow for selective formation of regions which favor generation of compounds of the ohmic contacts that are rich in carbon (Rascuná `023 ¶ [0039]) and achieve good ohmic contact (Rascuná `023 ¶ [0043],[0054],[0057]) and/or in order to achieve the benefits of Ti3SiC2 as taught by Seki (Seki ¶ [0013],[0019]) in a merged-PiN-Schottky (MPS) device (Rascuná `023 FIG. 1 ¶ [0004],[0005]).
Regarding claim 2, Seki in view of Rascuná `023 yields the method of claim 1, and Rascuná `023 further teaches (FIG. 6) wherein the modifying comprises irradiating a surface area (surface 59’ from FIG. 5) of the crystalline silicon carbide substrate (52) with at least one first thermal annealing laser beam (80, ¶ [0038],[0040],[0045]).
Regarding claim 3, Seki in view of Rascuná `023 yields the method of claim 2, and Rascuná `023 further teaches at least two subsequent laser annealing steps (number of pulses between 1 and 10, ¶ [0049],[0059]).
Regarding claim 10, Seki in view of Rascuná `023 yields the method of claim 1, and Seki in view of Rascuná `023 further yields wherein the thermal annealing (Seki’s annealing step ¶ [0017],[0018],[0038]) comprises: melting at least parts of the carbon-enriched silicon carbide portion and parts of the metallic contact material (“EVAPORATED MIXED FILM MADE OF TITANIUM, SILICON, AND CARBON”); and epitaxially reorganizing a ternary metallic phase portion obtained by the melting (i.e. forming Ti3SiC2, Abstract, ¶ [0002],[0013]-[0015],[0017],[0019],[0031]-[0034],[0038]-[0040]).
Regarding claim 11, Seki in view of Rascuná `023 yields the method of claim 1, and Seki further teaches wherein the metallic contact material comprises at least titanium (i.e. forming Ti3SiC2, Abstract, ¶ [0002],[0013]-[0015],[0017],[0019],[0031]-[0034],[0038]-[0040]).
Regarding claim 12, Seki in view of Rascuná `023 yields the method of claim 11, and Seki further teaches wherein the ternary metallic phase portion comprises TixSiyCz, and wherein x = 2.8-3.2, y=1, z= 1.8-2.2 (i.e. forming Ti3SiC2, Abstract, ¶ [0002],[0013]-[0015],[0017],[0019],[0031]-[0034],[0038]-[0040]).
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Application Publication Number 2011/0287626 A1 to Seki et al., “Seki”, in view of U.S. Patent Application Publication Number 2021/0328023 A1 to RASCUNÁ et al., “Rascuná `023”, as applied to claim 1 above, and further in view of U.S. Patent Application Publication Number 2021/0328022 A1 to Rascuna’ et al., “Rascunà `022”.
Regarding claim 8, although Seki in view of Rascuná `023 yields the method of claim 1, Seki and Rascuná `023 fail to clearly teach wherein a structured protective mask layer is provided on at least one side of the crystalline silicon carbide substrate when modifying the crystalline silicon carbide substrate and/or thermal annealing of at least a part of the contact layer, and wherein the protective mask layer has a reflectivity and/or absorption rate of radiation energy of a laser beam during laser thermal annealing higher than that of silicon carbide.
Rascunà `022 teaches (e.g. FIG. 10) using a structured protective mask having regions opaque (i.e. inherently a higher reflectivity and/or absorption rate) to a laser beam (96) during laser (95) annealing, in order to modify the crystalline silicon carbide substrate (i.e. form carbon-rich electrical contact regions Abstract, ¶ [0038],[0074],[0077],[0116]).
It would have been obvious before the effective filing date of the claimed invention to one having ordinary skill in the art to have performed the method of Seki in view of Rascuná `023 with a step of including a protective mask and laser annealing for forming carbon-rich ohmic contacts as taught by Rascunà `022 in order to locally heat up to a temperature in favor of generating ohmic contacts (Rascunà `022 ¶ [0053],[0054]) without heating or damaging other parts of the device/wafer (Rascunà `022 ¶ [0056],[0057],[0060]).
Allowable Subject Matter
Claims 4-7,9 objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
“Low-temperature, site selective graphitization of SiC via ion implantation and pulsed laser annealing” by Maxime G. Lemaitre et al. in APPLIED PHYSICS LETTERS 100, 193105 (2012) is referenced by Rascuná `023 ¶ [0039] and teaches (FIG. 1) wherein pulsed laser annealing forms carbon-rich silicon carbide.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ERIC A WARD whose telephone number is (571)270-3406. The examiner can normally be reached M-F 10-6 ET.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Matthew Landau can be reached at (571)272-1731. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/Eric A. Ward/Primary Examiner, Art Unit 2891
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