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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on December 29, 2025, has been entered.
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, 3, 9, and 21-22 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 Great Britain Patent No. GB 1448732 to Roland, et al. (“Roland”) and further in view of U.S. Patent Appl. Publ. No. 2002/0086119 to Hariharan, et al. (“Hariharan”) and still further in view of U.S. Patent No. 5,087,529 to Engel, et al. (“Engel”).
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. However, in at least p. 1, ll. 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, l. 89 to p. 2, l. 46 Roland further teaches that the boron nitride protective coating is provided with a sintering additive such as silica with p. 2, ll. 25-29 specifically teaching that the protective coating includes silica with up to 80% by weight of boron nitride. In p. 2, ll. 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 person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Roland and would be motivated to include a sintering additive such as silica within the boron nitride coating (108) utilized in the method of Rathod in order to promote densification of the boron nitride coating (108) such that it serves as a more effective barrier between the graphite susceptor (102) and quartz crucible (110).
Rathod and Roland do not teach the steps of plasma spraying the boron nitride and the sintering additive as claimed. 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 which comprises:
mixing the particles in one or more powder feeders with a plasma gas, the plasma gas being selected from the group consisting of argon, helium, nitrogen, hydrogen, or a combination thereof (see ¶¶[0029]-[0032] which teach 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); and
passing the particles and plasma gas through a plasma jet (see ¶¶[0029]-[0032] which specify that the powder particles and plasma gas are fed through a plasma jet).
In ¶[0030] Rathod specifically 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 person of ordinary skill in the art 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 Roland 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 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 p. 2, ll. 25-29 Roland specifically teaches that the protective coating includes silica with up to 80% of boron nitride by weight which therefore overlaps the claimed mass ratio of 1:20 to 1:1. Thus, a person of ordinary skill in the art 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.
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 p. 2, ll. 25-29 Roland specifically teaches that the protective coating includes silica with up to 80% of boron nitride by weight which therefore overlaps the claimed mass ratio of 1:20 to 1:1. Thus, a person of ordinary skill in the art 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.
Regarding claim 21, Rathod and Roland do not teach that the boron nitride particles and sintering additive particles are accelerated at a speed of 50 to 3000 m/s 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 accelerate the boron nitride and sintering additive particles of Rathod and Roland 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 Roland do not teach that the boron nitride particles and sintering additive particles 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.
Response to Arguments
Applicants’ arguments filed December 29, 2025, have been fully considered 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 claims 21-22 necessitated the introduction of U.S. Patent Appl. Publ. No. 2002/0086119 to Hariharan, et al. in place of U.S. Patent No. 5,087,529 to Engel, et al. to teach the newly added claim limitations.
Conclusion
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/KENNETH A BRATLAND JR/Primary Examiner, Art Unit 1714