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
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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 13-15, 19, 21, 22 and 24 is/are rejected under 35 U.S.C. 103 as being unpatentable over Syvajarvi et al (US 2009/0126624) in view of Vogel et al (US 2021/0148006) and Miyata et al (US 6,300,226).
Syvajarvi et al teaches a method of growing an epitaxial layer on a substrate of monocrystalline Silicon Carbide, SiC, comprising: providing a source material of monolithic polycrystalline Silicon Carbide (abstract; [0016]);
a substrate of SiC ([0036]) in a chamber of an inner container (inner container 32) of a crucible (container 50) with a distance therein between, arranging a carbon getter in the chamber of the crucible to achieve a stable and suitable Si/C stoichiometry in the inner container, the carbon getter having a melting point higher than 2200° C. and having an ability of forming a carbide layer with carbon species evaporated from SiC ([0009] and [0036] teaches a C-getter of tantalum, hafnium, tungsten and/or rhenium and tantalum foil control the vapor stoichiometry);
reducing pressure in the chamber ([0040] teaches a vacuum of 10-4 mbar is normally desired),
raising the temperature in the chamber to a growth temperature, such that a growth rate between 1 μm/h and 1 mm/h, is achieved, and keeping the growth temperature until a growth of at least 5 μm has been accomplished on the substrate ([0013], [0014], and [0045] teaches raising the temperature at a rate of 15-25°C/min until a desired growth temperature of 1900-2100°C is reached to achieve a epitaxial layer thickness of 500 mm can be achieved at a growth rate of more than 100 mm/hr)
Syvajarvi et al does not teach a source is SiC with a columnar micro-grain structure; and Syvajarvi et al does not teach a single crystal substrate; and Syvajarvi et al does not teach inserting an inert gas into the chamber and after insertion keeping the pressure higher than 0.01 mbar.
In a method of growing SiC single crystals, Vogel et al teaches PVT growth of single crystal SiC boules from a single crystal SiC seed crystal by using a polycrystalline SiC sublimation source; growth temperatures of 2000-2400°C and a small pressure of inert gas of 0.1 mbar to 100 mbar to control the growth rate; and the presence of a getter material of tantalum or tungsten ([0052]-[0065], [0075]-[0080]). Overlapping ranges are prima facie obvious (MPEP 2144.05).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Syvajarvi et al by using a monocrystalline seed substrate, as taught by Vogel et al, to grow single crystal SiC having a preferred orientation.
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Syvajarvi et al by adding an inert gas to increase the pressure to higher than 0.01 mbar, as taught by Vogel et al, to control the growth rate.
In a method of forming SiC, Miyata et al teaches a CVD-formed SiC product wherein the formation of fine polycrystalline SiC grains, in turn grow further into a crystalline structure having a columnar arrangement to form a SiC coating and a formed SiC product with a mean grain diameter of 2.1 mm, which clearly suggests a columnar micro-grain structure (col 4, ln 1-67, col 5, ln 1-67; col 6, ln 1-65). Miyata et al also teaches SiC grains having a crystalline structure with a columnar arrangement and the various characteristics of a CVD-formed SiC product such as mechanical strength, thermal properties, optical properties, and the like differ, depending on the characteristics of the SiC grains (col 5, ln 1-67).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Syvajarvi et al by using a polycrystalline SiC with a columnar micro-grain structure, as taught by Miyata et al, because the selection of a known material based on its suitability for its intended purpose is prima facie obvious (MPEP 2144.07) and a polycrystalline SiC with a columnar micro-grain have desired various properties.
Referring to claim 14-15, the combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches raising the temperature at a rate of 15-25°C/min until a desired growth temperature of 1900-2100°C is reached to achieve an epitaxial layer thickness of 500 mm can be achieved at a growth rate of more than 100 mm/hr (Syvajarvi [0013], [0014], and [0045]). Overlapping ranges are prima facie obvious (MPEP 2144.05).
Referring to claim 19, the combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches a CVD-formed SiC product wherein the formation of fine polycrystalline SiC grains, in turn grow further into a crystalline structure having a columnar arrangement to form a SiC coating and a formed SiC product with a mean grain diameter of 2.1 mm (Miyata et al col 4, ln 1-67, col 5, ln 1-67; col 6, ln 1-65).
Referring to claim 21, the combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches tantalum foil. (Syvajarvi [0009] and [0036] teaches a C-getter of tantalum, hafnium, tungsten and/or rhenium and tantalum foil control the vapor stoichiometry).
Referring to claim 22, the combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches the getter material, such as tantalum, tungsten, hafnium, molybdenum, niobium, hafnium, may be provided in the form of granular or powdery particles held in place by a porous wall, such as graphite (Vogel [0038]), which clearly suggests tantalum or tungsten comprises several pieces distributed throughout an inner container.
Referring to claim 24, the combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches a spacer with a height of 1 mm separates the source from the substrate (Syvajarvi [0036], Fig 4).
Claim(s) 16-18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Syvajarvi et al (US 2009/0126624) in view of Vogel et al (US 2021/0148006) and Miyata et al (US 6,300,226), as applied to claims 13-15, 19, 21, 22 and 24 above, and further in view of Soltani et al (US 2021/0301420).
The combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches all of the limitations of claim 16, as discussed above, except the pressure during the raising phase is between 150 mbar to 950 mbar and the pressure during the keeping phase is reduced to 0.1 mbar to 10 mbar, preferably to 1 mbar to 3 mbar.
In a method of making SiC, Soltani et al teaches an ambient pressure in the heating chamber is made near atmospheric pressure to suppress sublimation of the powdered material 50, until the temperature of the growth surface of the seed crystal 40 and the temperature of the powdered material 50 of SiC are raised to their target temperatures of 2100-2300°C; and when the target temperatures have been reached, a vacuum of (0.01 to 50 Torr) is created ([0047]). Overlapping ranges are prima facie obvious (MPEP 2144.05) and pressure is clearly taught to be result effective variable.
It would have been obvious to one of ordinary skill in the art at the time of filing to modify the combination of Syvajarvi et al, Vogel et al, and Miyata et al by changing the pressure during the raising phase is between 150 mbar to 950 mbar and the pressure during the keeping phase is reduced to 0.1 mbar to 10 mbar, as taught by Soltani et al, by optimizing the pressure during the heating phase to suppress sublimation, and optimizing the pressure during the growth phase to obtain a desired growth rate by conducting routine experimentation of a result effective variable (MPEP 2144.05).
Referring to claim 17, the combination of Syvajarvi et al, Vogel et al, Miyata et al and Soltani et al does not teach the claimed pumping rate. It would have been obvious to one of ordinary skill in the art at the time of filing to modify the combination of Syvajarvi et al, Vogel et al, Miyata et al and Soltani et al by using a pumping rate of 1-10 mbar/min to reduce pressure quickly to improve productivity.
Referring to claim 18, the combination of Syvajarvi et al, Vogel et al, Miyata et al and Soltani et al teaches the pressure during heating and growth are result effective variables, as discussed above. It would have been obvious to one of ordinary skill in the art at the time of filing to modify the combination of Syvajarvi et al, Vogel et al, Miyata et al and Soltani et al by optimizing pressure by conducting routine experimentation to obtain the claimed ranges.
Claim(s) 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Syvajarvi et al (US 2009/0126624) in view of Vogel et al (US 2021/0148006) and Miyata et al (US 6,300,226), as applied to claims 13-15, 19, 21, 22 and 24 above, and further in view of Sullivan (US 6,077,619).
The combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches all of the limitations of claim 20, as discussed above, except the micro grain of the source material is substantially oriented in the [111] or [110] crystal plane.
In a substrate of SiC, Sullivan teaches substrate comprises a polycrystalline silicon carbide outer surface with {111} crystallographic planes exposed on the working surface (Abstract; col 5, ln 10 to col 6, ln 65).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify the combination of Syvajarvi et al, Vogel et al, and Miyata et al by using a SiC substrate micro grain of the source material is substantially oriented in the [111] crystal plane, as taught by Sullivan, because the selection of a known material based on its suitability for its intended purpose is prima facie obvious (MPEP 2144.07).
Claim(s) 23 is/are rejected under 35 U.S.C. 103 as being unpatentable over Syvajarvi et al (US 2009/0126624) in view of Vogel et al (US 2021/0148006) and Miyata et al (US 6,300,226), as applied to claims 13-15, 19, 21, 22 and 24 above, and further in view of Akiyama (US 2017/0330747).
The combination of Syvajarvi et al, Vogel et al, and Miyata et al teaches all of the limitations of claim 23, as discussed above, except the surface of the substrate has a root mean square roughness lower than 5 nm.
In a method of making a silicon carbide substrate, Akiyama teaches surface of the single crystal silicon carbide substrate 1is formed into a smooth surface having a surface roughness RMS of 1.00 nm or less ([0041]). Overlapping ranges are prima facie obvious (MPEP 2144.05).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify combination of Syvajarvi et al, Vogel et al, and Miyata et al by polishing the surface of the substrate to produce a root mean square roughness lower than 5 nm, as taught by Akiyama, to reduce the roughness and provide a smooth surface for even growth thereon.
Response to Arguments
Applicant's arguments filed 03/13/2026 have been fully considered but they are not persuasive.
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., the monocrystalline SiC epitaxial layer is free from polytype and carbon inclusion defects and essentially free from basal plane dislocations) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993). The claimed invention does not recite any properties of the single crystal SiC. It is noted that there are many processing conditions and variables that can produce single crystals with different properties, such as purity of the source, temperature gradients, contamination etc; therefore, the alleged properties would not necessarily occur for the broadly claimed invention which does not recite any properties, thus is not limited to crystals with the alleged properties. Furthermore, it was known to one of ordinary skill in the art at the time of filing to form carbon inclusion defect free single crystal SiC by using conventional PVT and a high purity source, as evidenced by CN-108193282-A. CN 108193282 teaches using the high-purity silicon carbide raw material, high-quality, high-purity SiC single crystals without carbon inclusion defects can be obtained by growing SiC single crystals using the conventional PVT method (Computer translation [0028]).
In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). The Examiner admits that Syvajarvi does not explicitly teach the specific grain structure of the source material. However, Syvajarvi broadly teaches a substrate monolithic polycrystalline SiC as a source ([0016]). Miyata et al teaches a CVD-formed SiC product wherein the formation of fine polycrystalline SiC grains, in turn grow further into a crystalline structure having a columnar arrangement to form a SiC and SiC grains having a crystalline structure with a columnar arrangement and the various characteristics of a CVD-formed SiC product such as mechanical strength, thermal properties, optical properties, and the like differ, depending on the characteristics of the SiC grains (col 4, ln 1-67, col 5, ln 1-67; col 6, ln 1-65). Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to modify Syvajarvi et al by using a polycrystalline SiC with a columnar micro-grain structure, as taught by Miyata et al, because the selection of a known material based on its suitability for its intended purpose is prima facie obvious (MPEP 2144.07) and a polycrystalline SiC with a columnar micro-grain have desired various properties. Furthermore, Miyata et al teaches producing a high purity SiC substrate, and CN 108193282 teaches using the high-purity silicon carbide raw material, high-quality, high-purity SiC single crystals without carbon inclusion defects can be obtained by growing SiC single crystals using the conventional PVT method (Computer translation [0028]). The examiner maintains that use of a high purity source material would have been obvious to one of ordinary skill in the art at the time of filing to reduce defects in a PVT growth method.
Applicant’s argument that Syvajarvi does not teach a preference of a specific grain structure is noted but not found persuasive. Syvajarvi broadly teaches a polycrystalline SiC monolithic source; therefore, is open to any polycrystalline SiC, which would include the polycrystalline SiC with a columnar micro-grain structure, as taught by Miyata et al.
Applicant’s argument that directional microstructural growth during manufacturing the source material requires a high degree of process control is noted but not found persuasive. Miyata et al teaches the method of growing polycrystalline SiC with a columnar micro-grain structure; therefore, the method and high degree of process control was known to one of ordinary skill in the art at the time of filing.
In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). The examiner admits that Syvajarvi does not explicitly teach a monocrystalline SiC substrate. Syvajarvi teaches producing an epitaxial layer on a substate of SiC (abstract), and it is well known in the art that epitaxial growth is used with monocrystalline substrate to grow monocrystalline layers. Therefore, it would have been obvious to one of ordinary skill in the art at the time of filing to modify Syvajarvi et al by using a monocrystalline seed substrate, as taught by Vogel et al, to grow single crystal SiC having a preferred orientation.
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., a sublimation sandwich method) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993). The examiner maintains that Vogel et al and Syvajarvi et al teach sublimation growth; therefore, using a SiC monocrystalline seed would have been obvious to one of ordinary skill in the art at the time of filing.
In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). The examiner admits that Vogel et al does not teach the polycrystalline columnar structure. Miyata et al teaches a CVD-formed SiC product wherein the formation of fine polycrystalline SiC grains, in turn grow further into a crystalline structure having a columnar arrangement to form a SiC.
Applicant’s argument that Syvajarvi and Vogel do not relate to the same growth processes between the source are different is noted but not found persuasive. The examiner maintains that both process are sublimation of SiC sources; therefore, are similar growth processes.
Applicant’s argument that Miyata does not teach the SiC product can be used as a source material is noted but not found persuasive. Miyata teaches using the CVD-formed SiC product thus obtained as a substrate having high purity (col 5, ln 1-67). Syvajarvi broadly teaches a substrate monolithic polycrystalline SiC as a source ([0016]). Therefore, the SiC polycrystalline substrate having a high purity would be suitable as a monolithic SiC source in the process taught by Syvajarvi.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
CN 108193282 teaches using the high-purity silicon carbide raw material, high-quality, high-purity SiC single crystals without carbon inclusion defects can be obtained by growing SiC single crystals using the conventional PVT method (Computer translation [0028]).
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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MATTHEW J SONG whose telephone number is (571)272-1468. The examiner can normally be reached Monday-Friday 10AM-6PM.
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, Kaj Olsen can be reached at 571-272-1344. 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.
MATTHEW J. SONG
Examiner
Art Unit 1714
/MATTHEW J SONG/ Primary Examiner, Art Unit 1714
Prosecution Insights