DETAILED ACTION
Election/Restrictions
Applicant’s election of claims 1-3 in the reply filed on 114/05/2025 is acknowledged. Because applicant did not distinctly and specifically point out the supposed errors in the restriction requirement, the election has been treated as an election without traverse (MPEP § 818.01(a)).
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 1 is rejected under 35 U.S.C. 103 as being unpatentable over IMAZUMI et al. (JP 2018043899 A) with reference to the provided machine translation, hereinafter referred to as IMAZUMI, in view of Moore et al. (Characterization of pyrolytic boron nitride for semiconductor material processing, Journal of Crystal Growth, 106, 1990, pages 6-15), hereinafter referred to as MOORE.
Regarding claim 1, IMAZUMI teaches a hexagonal boron nitride powder (see IMAZUMI at paragraph [1]) having an average particle size (D50) of 2.0 to 6.0 µm and a specific surface area measured by a BET method of 4 to 12 m2/g (see IMAZUMI at paragraph [10]: value of D50 of 5 to 10 µm, and a BET specific surface area of 4 to 11 m2/g). IMAZUMI teaches ranges which are within and overlap with the claimed ranges. 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. See MPEP §2144.05(I).
While IMAZUMI is silent with respect to the hexagonal boron nitride powder having a concentration of a calcium element is 1 ppm or less, a concentration of a silicon element is 5 ppm or less, a concentration of a sodium element is 5 ppm or less, and a concentration of an iron element is 1 ppm or less on a surface of hexagonal boron nitride particle constituting the powder. IMAZUMI teaches utilizing hexagonal boron nitride powder in semiconductor device (see IMAZUMI at paragraph [2]), and discloses the subjecting hexagonal boron nitride powder to acid washing to obtain high purity white hexagonal boron nitride powder (see IMAZUMI at paragraph [48]).
However, MOORE discloses the properties of pyrolytic boron nitride (PBN) which make it an attractive material for the processing of semiconductor materials; these properties include purity, chemical and thermal stability (see MOORE at Abstract). MOORE also discloses that boron nitride exists as a hexagonal crystal (see MOORE at 3. Structure and morphology of pyrolytic boron nitride, first paragraph, p. 7). MOORE teaches that because of exposure to air and handling, the concentration of certain impurities at the surface of PBN will be greater than in the bulk; and that salts and most metals can be removed by (1) boiling in HCl or Aqua Regia, (2) firing for 1 h at 1200°C in pure dry nitrogen and 1% gaseous anhydrous HCl, or (3) baking at high temperature in ultra-high vacuum (see MOORE at 5. Purity of PBN, right column, second paragraph, p. 10). MOORE also teaches the upper limits of metal impurity concentration in PBN (see MOORE at 5. Purity of PBN, left column, first paragraph, p. 10 and Table 2). Table 2 shows the following concentrations of metal impurities: <1 ppm of Na, <5 ppm of Si, <2 ppm of Ca, <5 ppm of Fe. Additionally, MOORE teaches that pyrolytic boron nitride has proven to be a valuable yet economical container material for the elemental purification, compounding and growth of semiconductor crystals; and that optimization of PBN performance in these applications requires material of highest possible purity (see MOORE at 8. Conclusion, p. 14-15).
Both IMAZUMI and MOORE disclose hexagonal boron nitride for the application in semiconductor devices. Furthermore, IMAZUMI and MOORE disclose that high-purity hexagonal boron nitride can be achieved by acid washing (see IMAZUMI at paragraph [48] and MOORE at 5. Purity of PBN, right column, second paragraph, p. 10). Therefore, based on the teachings of MOORE that most metals can be removed by acid treatment, one of ordinary skill in the art would have anticipated the metal impurities such as Na, Ca, Si and Fe, to be less than 5 ppm after subjecting hexagonal boron nitride to acid treatment to obtain high-purity material as disclosed by IMAZUMI. Moreover, one of ordinary skill in the art would have been motivated to modify the hexagonal boron nitride powder of IMAZUMI to reduce the metal impurity to below 5 ppm as disclosed by MOORE, since MOORE explicitly teaches that optimization of PBN performance in semiconductor applications requires material of highest possible purity (see MOORE at 8. Conclusion, p. 14-15).
Therefore, it would have obvious to one of ordinary skill in the art prior to effective filing date of the claimed invention to have modified the hexagonal boron nitride powder of IMAZUMI by reducing the metal impurity to below 5 ppm as disclosed by MOORE, in order to obtain boron nitride of highest purity suitable for semiconductor applications.
Regarding claim 2, IMAZUMI as modified by MOORE teaches the hexagonal boron nitride powder according to claim 1, wherein the hexagonal boron nitride powder has an average aspect ratio (major axis/thickness) of 1 to 7 (see IMAZUMI at paragraphs [14]: the aspect ratio of hexagonal boron nitride particle is preferably 2.5 to 10; and [64](2): length/thickness ratio). IMAZUMI teaches range which overlaps with the claimed range.
Regarding claim 3, IMAZUMI as modified by MOORE teaches the hexagonal boron nitride powder according to claim 1, wherein the hexagonal boron nitride powder is a filler for resin (see IMAZUMI at paragraph [1]: a hexagonal boron nitride powder capable of obtaining a resin molded product having high insulation resistance and high thermal conductivity when filled in a resin as a filler).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Schmitt et al. Preparation of high-purity nitride powder, Union Carbide Corporation, Nuclear Division, Oak Ridge Y-12 Plant, 1969;
Takeda et al. (WO 2020032060) with reference to the US 20210163288 as an English translation.
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/A.A.K./Examiner, Art Unit 1731
/AMBER R ORLANDO/Supervisory Patent Examiner, Art Unit 1731