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
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1, 9, and 21-23 is/are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Appl. Publ. No. 2014/0182511 to Rathod, et al. (hereinafter “Rathod”) in view of U.S. Patent Appl. Publ. No. 2007/0054122 to Paisner, et al. (“Paisner”) and further in view of U.S. Patent Appl. Publ. No. 2002/0086119 to Hariharan, et al. (“Hariharan”).
Regarding claim 1, Rathod teaches a method for producing a single crystal silicon ingot from a silicon melt (see the Abstract, Fig. 1, and entire reference which teach a method of growing a Si ingot from a Si melt) comprising:
providing a graphite susceptor having an interior surface defining a cavity (see Fig. 1, ¶¶[0003]-[0004], and ¶¶[0013]-[0014] which teach providing a graphite susceptor (102) having an interior cavity (104));
depositing a coating onto the interior surface of the susceptor, the coating comprising boron nitride (see Fig. 1 and ¶¶[0015]-[0017] which teach forming a coating (108) on an interior surface of the susceptor (102) which, in one embodiment, is comprised of boron nitride),
wherein depositing the coating includes spraying the boron nitride onto the interior surface of the susceptor (see Fig. 1 and ¶¶[0023]-[0028] which teach that the coating (108) may be sprayed onto the interior surface of the graphite susceptor (102));
positioning a quartz crucible in the cavity of the susceptor, the quartz crucible having an outer surface that contacts the coating (see Fig. 1, ¶¶[0003]-[0004], and ¶¶[0013]-[0015] which teach positioning a quartz crucible (110) into the cavity of the susceptor (102) such that the quartz crucible (110) contacts the coating (108));
adding polycrystalline silicon to the quartz crucible; heating the polycrystalline silicon to cause the silicon melt to form in the quartz crucible; and pulling the single crystal silicon ingot from the silicon melt (see ¶¶[0003]-[0005] which teach that polysilicon is added to the crucible (110), the polysilicon is heated to form a melt, and a single crystal is grown from as seed by slow extraction as part of the Czochralski crystal growth process).
Rathod does not teach that the coating comprises a sintering additive, wherein the sintering additive promotes densification of the boron nitride or the step of forming a coated particulate mixture comprising boron nitride particles coated with the sintering additive. However, in Figs. 1-2 and ¶¶[0018]-[0072] as well as elsewhere throughout the entire reference Paisner teaches a method of producing boron nitride (BN) powder particles in which the surface is functionalized using a coating which, as disclosed in at least claims 11 and 32, is comprised of a material such as alumina, silica, or zirconia. In at least ¶[0004] Paisner teaches that BN has very poor rheological properties and produces mixtures that are so viscous that it is difficult to disperse. Then in Fig. 2 and Examples 1-5 in ¶¶[0070]-[0078] Paisner teaches that forming a coating on the BN particles produces a corresponding reduction in the viscosity and, consequently, an improvement in its rheological properties. Thus, a PHOSITA prior to the effective filing date of the invention would be motivated to produce the BN coating utilized in the method of Rathod using BN particles coated with an additive such as alumina, silica, or zirconia in order to reduce the viscosity of the mixture such that a more uniform and consistent BN coating may be formed on interior surfaces of the graphite susceptor (102) of Rathod.
Rathod and Paisner do not teach the steps of plasma spraying the coated particulate mixture comprising the boron nitride particles coated with the sintering additive onto the interior surface of the susceptor. However, in ¶¶[0023]-[0044] as well as elsewhere throughout the entire reference Hariharan teaches an analogous method of forming a protective layer between a quartz crucible and a graphite susceptor by plasma spraying. In ¶¶[0029]-[0032] Hariharan specifically teaches that the coating materials in powder form are fed into a plasma jet through one or more powder feeders along with a plasma gas which is in the form of argon, helium, nitrogen, hydrogen, or a combination thereof. In ¶[0030] Rathod further teaches that plasma spray deposition has the advantages of high efficiency in terms of throughput, processing step, energy, and ease of operation and is capable of depositing materials that have very high melting points. Thus, a PHOSITA prior to the effective filing date of the invention would be motivated to utilize plasma spraying to feed a powder mixture comprised of boron nitride and the sintering additive as taught by Rathod and Paisner through a plasma jet in order to efficiently deposit an uniform, consistent, and higher quality layer of the desired boron nitride coating onto the susceptor in the method of Rathod.
Regarding claim 9, Rathod does not teach that the sintering additive comprises silica, silicon carbide, boric acid, alumina, yttria, zirconia, aluminum nitride, lanthana, or a combination thereof. However, as noted supra with respect to the rejection of claim 1, in Figs. 1-2 and ¶¶[0018]-[0072] as well as elsewhere throughout the entire reference Paisner teaches a method of producing boron nitride (BN) powder particles in which the surface is functionalized using a coating which, as disclosed in at least claims 11 and 32, is comprised of a material such as alumina, silica, or zirconia. Thus, a PHOSITA prior to the effective filing date of the invention would be motivated to
Regarding claim 21, Rathod and Paisner do not teach that the boron nitride particles coated with sintering additive are accelerated at a speed of 50 to 3000 m/s through a plasma jet. However, as noted supra with respect to the rejection of claim 1, in ¶¶[0023]-[0044] as well as elsewhere throughout the entire reference Hariharan teaches an analogous method of forming a protective layer between a quartz crucible and a graphite susceptor by plasma spraying. In ¶[0031] Hariharan specifically teaches that the powder particles are accelerated and heated up to velocities of 50 to 200 m/s and a temperature of about 2,000 to 3,000 °C. The high-speed softened or melted particles impact on the substrate surface and solidify rapidly to form the desired coating. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to utilize the plasma spray deposition technique of Hariharan to accelerate the boron nitride and sintering additive particles of Rathod and Paisner to a speed in the overlapping range of 50 to 200 m/s in order to cause the particle to impact onto the substrate surface and solidify rapidly into the desired coating.
Regarding claim 22, Rathod and Paisner do not teach that the boron nitride particles coated with sintering additive are heated to a temperature between 2,000 °C and 3,000 °C through the plasma jet. However, as noted supra with respect to the rejection of claim 1, in ¶¶[0023]-[0044] as well as elsewhere throughout the entire reference Hariharan teaches an analogous method of forming a protective layer between a quartz crucible and a graphite susceptor by plasma spraying. In ¶[0031] Hariharan specifically teaches that the powder particles are accelerated and heated up to velocities of 50 to 200 m/s and a temperature of about 2,000 to 3,000 °C. The high-speed softened or melted particles impact on the substrate surface and solidify rapidly to form the desired coating. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to utilize the plasma spray deposition technique of Hariharan to heat the boron nitride and sintering additive particles of Rathod and Roland to a temperature in the overlapping range of 2,000 to 3,000 °C in order to melt or soften the particles such that they impact onto the substrate surface and solidify rapidly into the desired coating.
Regarding claim 23, Rathod and Hariharan do not teach that the coated particulate mixture is formed by adding the sintering additive to an aqueous solution; washing the boron nitride particles with the aqueous solution comprising the sintering additive in a slurry; and drying the slurry to remove water. However, as noted supra with respect to the rejection of claim 1, in Figs. 1-2 and ¶¶[0018]-[0072] as well as elsewhere throughout the entire reference Paisner teaches a method of producing boron nitride (BN) powder particles in which the surface is functionalized using a coating which, as disclosed in at least claims 11 and 32, is comprised of a material such as alumina, silica, or zirconia. In at least ¶¶[0051]-[0060] Paisner teaches a wet coating method in which the BN particles and the coating are brought into contact with an aqueous solution to form a slurry which permits the coating to from on the BN particles. The BN particles are then calcined at 200 to 1,100 °C at a temperature sufficient to form the desired oxide coating such as alumina, silica, or zirconia. Thus, a PHOSITA prior to the effective filing date of the invention would recognize that the coated BN powder particles utilized to form the BN coating in Rathod may be produced using a wet method which includes adding the BN particles and the sintering additive to an aqueous solution to form a slurry followed by drying the slurry with the motivation for doing so being to promote adhesion of the sintering additive to the surface of the BN particles such that a more uniform coating is obtained.
Claim 3 is/are rejected under 35 U.S.C. 103 as being unpatentable over Rathod in view of Paisner and further in view of Hariharan and still further in view of Great Britain Patent No. GB 1448732 to Roland, et al. (“Roland”).
Regarding claim 3, Rathod does not teach that a mass ratio of the sintering additive to the boron nitride in the coating is from 1:20 to 1:1. However, as noted supra with respect to the rejection of claim 1, in Figs. 1-2 and ¶¶[0018]-[0072] as well as elsewhere throughout the entire reference Paisner teaches a method of producing boron nitride (BN) powder particles in which the surface is functionalized using a coating which, as disclosed in at least claims 11 and 32, is comprised of a material such as alumina, silica, or zirconia. In at least ¶¶[0060]-[0061] Paisner specifically teaches that the BN in powder or paste form includes 30 to 80 wt. % of BN to total weight of the coating compound which therefore overlaps the claimed mass ratio of 1:20 to 1:1. Thus, a PHOSITA prior to the effective filing date of the invention would be motivated to utilize a protective coating comprised of up to 80% boron nitride by weight with the sintering additive in order to reduce its viscosity such that a more uniform BN layer and, consequently, a more effective barrier is formed between the graphite susceptor (102) and quartz crucible (110) of Rathod.
Alternatively, in at least p. 1, II. 12-43 Roland teaches the use of a boron nitride coating between a Si-containing article and graphite in order to inhibit the occurrence of a reaction between graphite and Si. Thus, the teachings of Roland are relevant to the problem to be solved, which is to prevent the occurrence of a reaction between the silica crucible (110) and graphite susceptor (102) during crystal growth in Rathod. Then in p. 1, I. 89 to p. 2, I. 46 Roland further teaches that the boron nitride protective coating is provided with a sintering additive such as silica with p. 2, II. 25-29 specifically teaching that the protective coating includes silica with up to 80% by weight of boron nitride which therefore overlaps the claimed mass ratio of 1:20 to 1:1. In p. 2, II. 96-114 Roland further teaches that the addition of silica to boron nitride promoted substantial densification of the boron nitride layer, thereby improving its performance as a protective coating. Thus, a PHOSITA prior to the effective filing date of the invention would be motivated to utilize a protective coating comprised of up to 80% boron nitride by weight with silica as a sintering additive in order to promote densification of the boron nitride layer such that it functions as a more effective barrier between the graphite susceptor (102) and quartz crucible (110) of Rathod.
Response to Arguments
Applicants’ arguments filed May 28, 2026, have been fully considered and are persuasive, but they are moot in view of the new grounds of rejection set forth in this Office Action. Applicants’ amendments to claim 1 and the addition of new claim 23 necessitated the introduction of U.S. Patent Appl. Publ. No. 2007/0054122 to Paisner, et al. to teach the newly added claim limitations.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. U.S. Patent Appl. Publ. No. 2022/0195141 to Minorikawa, et al. relates to a method for producing silica-coated BN particles.
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.
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/KENNETH A BRATLAND JR/Primary Examiner, Art Unit 1714
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