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.
Claims 1-7 are rejected under 35 U.S.C. 103 as being unpatentable over Lin (“Light-Emitting Two-Dimensional Ultrathin Silicon Carbide”, 2012) in view of Chabi et al. (“From graphene to silicon carbide: ultrathin silicon carbide flakes” and “Supporting Information”, 2016) (Chabi).
Regarding claim 1, Lin teaches the fabrication of 2D SiC nanosheets by sonicating SiC powders in NMP or IPA for 24 hours, which falls within the claimed range. The obtained solutions were centrifuged to remove big particle remnants (Lin, p. 3952, 2. Experimental Details) (i.e., A method for forming two-dimensional (2D) silicon carbide (SiC) comprising: providing a plurality of SiC particles; forming a solution comprising the plurality of SiC particles and a solvent; sonicating the solution for 24 hours; and centrifuging the solution that was sonicated to extract 2D SiC).
Further, as Lin teaches forming two-dimensional silicon carbide (Lin, Title; Abstract) and observing a hexagonal lattice configuration through TEM imaging of the SiC nanosheets (Figure 1(e)), it is clear that Lin formed a plurality of 2D SiC nanosheets that are monolayers and exhibit a hexagonal planar structure as determined by transmission electron microscopy (TEM), i.e., direct observation. Further, Lin teaches some of the SiC nanosheets could be monolayers as the heights of the SiC are consistent with that of graphene which is a monolayer (Lin, p. 3953, Col. 2, Paragraph 1).
However, Lin does not explicitly teach the plurality of SiC particles has a dimension of about 4 μm or more.
With respect to the difference, Chabi teaches the synthesis of 2D SiC nanosheets from the sonication of 3D SiC (Chabi, p. 5-6, Experimental methods). Chabi specifically teaches using 3D SiC with dimensions in the micron range including greater than 4 μm as the starting 3D SiC material prior to sonication (Chabi, Supporting Information, Figure S2).
As Chabi expressly teaches, the 3D SiC used formed the largest and thinnest SiC flakes, which are expected to be semiconducting and an ideal replacement for 3D and even 1D SiC (Chabi, p. 5, Col. 1, Paragraph 2).
Chabi is analogous art as it is drawn to forming 2D SiC flakes through sonication (Chabi, p. 5-6, Experimental methods).
In light of the motivation of using the 3D SiC of Chabi as the starting material, it therefore would have been obvious to one of ordinary skill in the art to modify the starting material of Lin by using larger 3D SiC particles in order to form larger SiC flakes for semiconductors, and thereby arrive at the claimed invention.
Regarding claims 2 and 3, Lin, in view of Chabi, teaches the method of claim 1, wherein the 3D SiC particles include multiple dimensions in the micron range as shown in Figure S2 of Chabi (Chabi, Supporting Information, Figure S2). It is clear in Figure S2(a) that the surface area of the 3D SiC particles would be greater than 8 μm2 as the length and width are greater than 50 μm.
Although there are no disclosures on the 3D SiC particles having an average length of about 18 μm, and an average diameter of about 1.5 μm as presently claimed, it has long been an axiom of United States patent law that it is not inventive to discover the optimum or workable ranges of result-effective variables by routine experimentation. In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003) ("The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages."); In re Boesch, 617 F.2d 272, 276 (CCPA 1980) ("[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art."); In re Aller, 220 F.2d 454, 456 (CCPA 1955) ("[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation."). "Only if the 'results of optimizing a variable' are 'unexpectedly good' can a patent be obtained for the claimed critical range." In re Geisler, 116 F.3d 1465, 1470 (Fed. Cir. 1997) (quoting In re Antonie, 559 F.2d 618, 620 (CCPA 1977)).
At the time of the invention, it would have been obvious to one of ordinary skill in the art to vary the length and diameter of the SiC particles, including over the ranges presently claimed, in order to form the desired size of 2D SiC for the semiconductor, and thereby arrive at the claimed invention.
Regarding claim 4, Lin, in view of Chabi, teaches the method of claim 1, wherein although there are no disclosures on the ratio of SiC to solvent being 0.1 mg per 1 mL or greater as presently claimed, it has long been an axiom of United States patent law that it is not inventive to discover the optimum or workable ranges of result-effective variables by routine experimentation. In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003) ("The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages."); In re Boesch, 617 F.2d 272, 276 (CCPA 1980) ("[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art."); In re Aller, 220 F.2d 454, 456 (CCPA 1955) ("[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation."). "Only if the 'results of optimizing a variable' are 'unexpectedly good' can a patent be obtained for the claimed critical range." In re Geisler, 116 F.3d 1465, 1470 (Fed. Cir. 1997) (quoting In re Antonie, 559 F.2d 618, 620 (CCPA 1977)).
At the time of the invention, it would have been obvious to one of ordinary skill in the art to vary the ratio of SiC particles to solvent, including over the amounts presently claimed, in order to achieve the desired sonication results.
Regarding claim 5, Lin, in view of Chabi, teaches the method of claim 1, wherein the solvent for sonication is NMP or IPA (Lin, p. 3952, 2. Experimental Details).
Regarding claim 6, Lin, in view of Chabi, teaches the method of claim 1, but does not explicitly teach wherein sonicating further comprises adding liquid to the solution being sonicated to compensate for liquid lost during sonication.
With respect to the difference, Chabi teaches the synthesis of 2D SiC nanosheets from the sonication of 3D SiC (Chabi, p. 5-6, Experimental methods). Chabi specifically teaches after every 10 min bath sonication in propanol, the upper suspension was put away to remove a small number of 1D nanowires and propanol was added before further sonication (Chabi, p. 6, Experimental methods).
As Chabi expressly teaches, the additional propanol was added to further dilute the suspension (Chabi, p. 6, Experimental methods).
In light of the motivation of adding additional liquid during sonication as disclosed by Chabi, it therefore would have been obvious to one of ordinary skill in the art to modify the method of Lin by adding more NMP or IPA in order to further dilute the suspension, and thereby arrive at the claimed invention.
Regarding claim 7, Lin, in view of Chabi, teaches the method of claim 1, wherein the obtained solutions were centrifuged at speeds varying from 4000 to 12000 rpm (Lin, p. 3952, 2. Experimental Details), which falls within the claimed range.
Response to Arguments
In response to applicant’s amendments to claims 1, 4, and 5, the previous claim objections are withdrawn from the record.
Applicant primarily argues:
“Lin's process uses solution sonication in NMP or IPA and centrifugation (see section 2. Experimental Details), but Lin expressly reports co-formation of graphene (pure carbon):"Graphene, which is also produced in this process, naturally forms the ultrathin substrate facilitating the TEM characterization of 2D SiC." See Lin, 3. Results and Discussion; Fig. 1.
Moreover, the structural assignment relayed by Lin is tentative and directed to graphite (pure carbon), not a directly observed SiC monolayer, or even silicon carbide. In Fig.1, Lin provides no evidence/proof to confirm the silicon carbide nature of the shown flakes. As noted in the Results and Discussion section of Lin and supported by Fig. 1d-lf, Fig. 2, it is suggested that "these nanoflakes most possibly have a graphite (0001)/(0001) chemical structure." Additionally, the AFM height data for the "nanoflakes" described in Lin are on the order of sub-nanometer to nanometers (see Fig. 3 discussion), and Lin links the observed flakes to mixed phases on graphene supports, not to a monolayer of SiC directly observed by TEM to exhibit a hexagonal planar lattice intrinsic to a single SiC layer. In the conclusion section of Lin paper, it is not even claimed that 2D SiC or monolayer SiC were fabricated, because they never achieved it. Instead, they stated, "The ultrathin SiC most possibly has a graphitic structure....". Thus, Lin himself never claimed the formation of planar monolayer 2D silicon carbide, and provided no strong proof image of even silicon carbide nanosheets.
As such, Lin shows mixed products and does not disclose a TEM-confirmed SiC
monolayer exhibiting a hexagonal planar structure as claimed in independent claim 1 (or even pure silicon carbide). Additionally, in Figure 2 (Lin) they incorrectly label the XRD peak around 26 (two-theta) as graphitic silicon carbide. This peak belong to pure carbon, not silicon carbide. Using the word "graphitic silicon carbide" is incorrect and misleading. Silicon carbide does not have an XRD peak at around 26 degree. This XRD peak further confirms that the shown flakes in this study most likely belong to graphite, as compared to Applicant's claimed silicon carbide. Furthermore, the fact that Lin's XRD does not even exhibit peaks for silicon carbide is another strong proof that Lin never produced true 2D SiC. One skilled in the art would only observe a pronounced XRD peak from 3D materials (e.g. silicon carbide precursor, or bulk silicon carbide here). Thus, the Lin reference shows results from graphite/graphene flake and bulk SiC precursor, and it would not be obvious or possible for one skilled in the art to use the teachings of Lin to produce the claimed product recited by the claimed method.”
Remarks, p. 8-9
The examiner respectfully traverses as follows:
While applicant argues that Lin does not teach a directly observed monolayer, Lin does conclude based on evidence that some of the SiC nanosheets could be monolayers, and therefore there is a reasonable expectation of success. Further, the claims only require a hexagonal planar structure to be directly observed, which Lin teaches observing using TEM as disclosed in Fig. 1(e).
Further, while applicant argues that the Lin does not teach the formation of two-dimensional SiC, Lin explicitly states that 2D SiC nanosheets were synthesized by sonication of SiC powders in NMP or IPA.
Additionally, while applicant that the data and images shown by Lin are not pointing to the formation of 2D SiC, it is noted that “the arguments of counsel cannot take the place of evidence in the record”, In re Schulze, 346 F.2d 600, 602, 145 USPQ 716, 718 (CCPA 1965). It is the examiner’s position that the arguments provided by the applicant regarding the data disclosed by Lin being drawn to graphene rather than SiC must be supported by a declaration or affidavit. As set forth in MPEP 716.02(g), “the reason for requiring evidence in a declaration or affidavit form is to obtain the assurances that any statements or representations made are correct, as provided by 35 U.S.C. 24 and 18 U.S.C. 1001”.
Applicant further argues:
“The synthetic route disclosed in Chabi produces a complex 3D SiC network, namely
foam, with 1D nanowires, while sonication detaches and separates 2D flakes from 1D nanowires The supporting information described in Chabi establishes coexistence of 1D and 2D morphologies arising from a 3D precursor, but it does not disclose a monolayer SiC nor a direct TEM observation of a hexagonal planar monolayer lattice as required by claim 1.
…
Consequently, as the Office relies on Chabi for teaching starting material dimensions, and on Lin for process steps., even if one were to combine the 3D foam/nanowire system of Chabi with the liquid sonication and centrifugation process of Lin, neither reference teaches or suggests the amended feature that the extracted product is a monolayer SiC that "exhibits a hexagonal planar structure under direct observation using TEM." The cited art references do not establish that the claimed monolayer property is inherent to either process. The characterization described in Lin concludes mixed products, graphene plus graphitic SiC (from the precusor), and never produced monolayer SiC. Furthermore, the flakes described in Chabi are formed in a 3D network and are not shown to be monolayers, rather, theyare ultra-thin silicon carbide nanosheets, not 2D monolayer SiC as claimed.”
Remarks, p. 9
The examiner respectfully traverses as follows:
It is noted that while Chabi does not disclose all the features of the present claimed invention, Chabi is used as a teaching reference, namely to teach the plurality of SiC particles having a dimension of 4 μm or more, in order to form larger flakes, and therefore, it is not necessary for this secondary reference to contain all the features of the presently claimed invention, In re Nievelt, 482 F.2d 965, 179 USPQ 224, 226 (CCPA 1973), In re Keller 624 F.2d 413, 208 USPQ 871, 881 (CCPA 1981). Rather this reference teaches a certain concept, and in combination with the primary reference, discloses the presently claimed invention.
Applicant further argues:
“Applicant notes that Yaghoubi critically evaluates the results described in Lin and attribute the observed signals to graphene and hexagonal SiC precursor peaks rather than monolayer SiC, noting that Lin reported "large amounts of graphene along with this '2D SiC'... [and] all the observed XRD peaks can be assigned to either hexagonal SiC (the precursor) or graphite... These pieces of evidence unequivocally lead us to believe what has been observed is a form of graphene." See Yaghoubi, section "Graphitic SiC: Mirage versus Reality
Yaghoubi also summarizes the claim of exfoliating hexagonal SiC using NMP/IPA in the following passage:
"Lately, Lin ... has claimed to have successfully produced 2D SiC by exfoliating
hexagonal SiC crystals using polar solvents such as N-methylpyrrolidone (NMP) and isopropyl alcohol (IPA)."), and then explains why those observations are consistent with graphene and graphitized surfaces rather than monolayer SiC. Id.
While Yaghoubi is not cited by the Office as a prior art reference, it is supportive of Applicant's position in that even in retrospect the field has rejected Lin's claim on 2D SiC fabrication. This reinforces that Lin does not teach, and one of ordinary skill would not have reasonably expected to achieve, the presently claimed TEM-observed SiC monolayer with a hexagonal planar structure.”
Remarks, p. 9-10
The examiner respectfully traverses as follows:
While applicant points to Yaghoubi for support, Yaghoubi provides no sufficient evidence (i.e., data) to support their position. It is significantly noted, Lin explicitly discloses “Light-Emitting Two-Dimensional Ultrathin Silicon Carbide” (Lin, Title; emphasis added), which would correspond to a SiC monolayer. Further, as disclosed above, Lin does conclude based on evidence that the formed SiC nanosheets have a thickness in the range of monolayer graphene and therefore some of the SiC nanosheets could be monolayers (Lin, p. 3953, Col. 2, Paragraph 1), and therefore there is a reasonable expectation of success of forming monolayer 2D SiC. Further, Lin teaches the hexagonal lattice configuration observed by TEM in Figure 1(e), which would correspond to a hexagonal planar structure for monolayer 2D SiC.
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 Catriona Corallo whose telephone number is (571)272-8957. The examiner can normally be reached Monday-Friday, 8am-5pm.
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/C.M.C./Examiner, Art Unit 1732
/CORIS FUNG/Supervisory Patent Examiner, Art Unit 1732