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) 6-10 is/are rejected under 35 U.S.C. 103 as being unpatentable over Enoki et al (JP 59-18191), an English computer translation (CT) is provided, in view of Minami et al (JP 2001-199794), an English computer translation (CT2) is provided, and Xiao et al (US 2017/0253993).
Enoki et al teaches equipment for manufacturing monocrystalline silicon, comprising: a quartz crucible 3, the quartz crucible 3 being used for accommodating a silicon melt 9; a first gas-conveying apparatus, the first gas-conveying apparatus (gas inlet 7/8 being used for supplying inert gas and carbon-containing gas/CO gas) being used for conveying a carbon monoxide gas onto a liquid surface of the a silicon melt; and a crystal pulling apparatus, the crystal pulling apparatus being used for pulling a monocrystalline silicon by a Czochralski method (Fig 1; CT [0001]-[0003]).
Referring to claim 6, Enoki et al teaches carbon doping in Czochralski process using a CO gas, as discussed above. Enoki et al does not teach a nitrogen doped melt.
In an apparatus for Czochralski crystal growth, Minami et al teaches pulling a silicon single crystal 1 doped with both and carbon from a silicon melt doped with nitrogen and carbon; nitrogen dopant is added to the melt by adding a predetermined amount of silicon nitride; the polysilicon held within a quartz crucible 4 is heated and melt by a heater 5; and a radiation shield (reflector) 10 arranged above the quartz crucible 4; and argon (Ar) gas is supplied to the top of the apparatus and flows downward to the melt surface (Fig 1; CT2 [0020]-[0041]). Minami et al teaches Czochralski growth of a silicon single crystal doped with both nitrogen and carbon, wherein the silicon melt is doped with nitrogen by melting silicon nitride. Minami et al teaches doping with nitrogen and carbon simultaneously provides a synergistic effect, allowing high density oxygen precipitates to be precipitated uniformly within the surface, thereby improving the effect of intrinsic gettering (CT2 [0033], [0061]).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Enoki et al by doping the melt with nitrogen and carbon, as taught by Minami et al, to produce high density oxygen precipitates to be precipitated uniformly within the surface, thereby improving the effect of intrinsic gettering (Minami CT2 [0033], [0061]).
The combination of Enoki et al and Minami et al does not teach the carbon monoxide gas reacts with the nitrogen-doped silicon melt and components in the quartz crucible to form silicon nitride. This feature would be expected because the combination of Enoki et al and Minami et al teaches a Czochralski growth method comprising supplying carbon monoxide, a nitrogen-doped silicon melt and compounds in a quartz crucible; therefore, a similar reaction would be expected to occur and produce silicon nitride because a similar method is expected to produce similar results. It is noted that applicant teaches the process of supplying carbon monoxide gas onto the liquid surface of a nitrogen doped silicon melt and SiO would generate silicon nitride (See [0012] of the specification).
The combination of Enoki et al and Minami et al does not explicitly teach a temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen-doped silicon melt.
In a Czochralski crystal growth method, Xiao et al teaches nitrogen doping a silicon melt comprising fully mixing and melting silicon nitride and polysilicon at 1900-2000°C (i.e. higher than the melting point of silicon nitride); then the obtained melt is cooled to make the temperature of the central area of the melt surface be about 1400°C (i.e. the melting point of silicon), and crystal seed is seeded, then the predetermined crystal pulling rate is applied to pull the crystal rod upward until reaching the predetermined length of the crystal rod (abstract; [0016]-[0040]), which is clearly suggests the temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen-doped silicon melt because applicant teaches “For the generated silicon nitride (Si.sub.3N.sub.4), due to its high melting point, it still exists in a solid state at high temperatures, so it will return to the melt, so that the nitrogen volatilized from the melt will be returned to the melt, resulting in the loss of nitrogen is reduced and improving the situation of the nitrogen concentration decline in the pulled entire monocrystalline silicon ingot.” Therefore, by controlling the temperature to be less than the melting point of silicon nitride, the generated silicon nitride is expected to return to the melt.
It would have been obvious to one of ordinary skill in the art at the time of filing to modify the combination of Enoki et al and Minami et al by controlling the temperature of the Czochralski growth process to be about 1400°C after melting the silicon nitride dopant, as taught by Xiao et al, to grow a nitrogen doped Si crystal using growth temperatures known in the art. Changes in temperatures are prima facie obvious (MPEP 2144.05).
Referring to claim 7, the combination of Enoki et al, Minami et al and Xiao et al teaches melting silicon nitride (Minami CT2 [0032]).
Referring to claim 8-10, the combination of Enoki et al, Minami et al and Xiao et al teaches supplying argon gas and CO (carbon monoxide) from the top of the apparatus to the melt surface which is guided to the melt surface using a radiation shield 10 (Enoki Fig 1; Minami Fig 1).
Response to Arguments
Applicant's arguments filed 10/30/2025 have been fully considered but they are not persuasive.
The applicant’s argument that the applicant’s teaching in the SUMMARY are about the description of the claimed invention rather than the prior art is noted but not found persuasive. Applicant’s arguments are not persuasive because the examiner’s reliance on applicant’s SUMMARY is merely to show the silicon nitride would be expected to return to the melt since the silicon nitride has a high melting point, and the prior art teaches maintaining a growth temperature of about 1400°C which is below the melting point of silicon nitride.
Applicant’s argument that Xiao does not teach silicon nitride is controlled to remain solid or solid silicon nitride returns to the melt cycle is noted but not found persuasive. The Examiner admits the claimed feature is not explicitly taught by the prior art, however the Examiner maintains that the claimed feature would be expected based on the combined teachings of the prior art. The combination of Enoki et al and Minami et al teaches a Czochralski growth method comprising supplying carbon monoxide, a nitrogen-doped silicon melt and compounds in a quartz crucible; therefore, a similar reaction would be expected to occur and produce silicon nitride because a similar method is expected to produce similar results. It is noted that applicant teaches the process of supplying carbon monoxide gas onto the liquid surface of a nitrogen doped silicon melt and SiO would generate silicon nitride (See [0012] of the specification). Xiao et al teaches nitrogen doping a silicon melt comprising fully mixing and melting silicon nitride and polysilicon at 1900-2000°C (i.e. higher than the melting point of silicon nitride); then the obtained melt is cooled to make the temperature of the central area of the melt surface be about 1400°C (i.e. the melting point of silicon), and crystal seed is seeded, then the predetermined crystal pulling rate is applied to pull the crystal rod upward until reaching the predetermined length of the crystal rod (abstract; [0016]-[0040]), which is clearly suggests the temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen-doped silicon melt because applicant teaches “For the generated silicon nitride (Si.sub.3N.sub.4), due to its high melting point, it still exists in a solid state at high temperatures, so it will return to the melt, so that the nitrogen volatilized from the melt will be returned to the melt, resulting in the loss of nitrogen is reduced and improving the situation of the nitrogen concentration decline in the pulled entire monocrystalline silicon ingot.” Therefore, by controlling the temperature to be less than the melting point of silicon nitride, the generated silicon nitride is expected to return to the melt. The examiner maintains that the “a temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen doped silicon melt” merely requires a teaching to control the temperature of the silicon nitride to be less than the melting point of silicon nitride; and the prior art clearly teaches controlling the temperature to be about 1400°C, thus meets the claimed limitation.
In response to applicant's argument that the prior art does not teach “a temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen doped silicon melt”, the fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985). The examiner maintains that the “a temperature of the silicon nitride is controlled to cause the silicon nitride to exist in a solid state and return to the nitrogen doped silicon melt” merely requires a teaching to control the temperature of the silicon nitride to be less than the melting point of silicon nitride; and the prior art clearly teaches controlling the temperature to be about 1400°C, thus meets the claimed limitation. The examiner maintains that applicant teaches “For the generated silicon nitride (Si3N4), due to its high melting point, it still exists in a solid state at high temperatures, so it will return to the melt, so that the nitrogen volatilized from the melt will be returned to the melt” (See [0012] of the specification); therefore, by controlling the temperature of the process to be less than the melting point of SiN, the SiN will necessarily return to the melt, as evidenced by applicant’s disclosure. There is no additional processing step that distinguishes the claimed invention from the teachings of the prior art. The only differences is that applicant recognized an advantage of having the SiN return to the melt because of the temperatures conventionally used in Czochralski silicon single crystal manufacturing using a melt doped with nitrogen and carbon monoxide gas.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Takanashi et al (US 2011/0259260) teaches a thermal radiation shield 16 can guide the purge gas to the lower space of the chamber 11, thereby enhancing the flow straightening property of the purge gas. Consequently, evaporated materials evaporated from the melt surface are efficiently entrained in the purge gas and can be discharged outside the chamber 11 with deposition thereof on peripheral components suppressed; and the evaporation amount of the dopant from the silicon melt can be controlled to thereby improve the stability in the resistivity distribution of the silicon single crystal in the pull-up direction ([0056], [0070]; Fig 1, 8A and 8B).
Nishio et al (US 5,041,186) teaches a Czochralski crystal growth apparatus comprising an argon source 31 and CO source 32 and supplying the gases to the melt in the crucible (Fig 1 and Fig 7).
Hourai et al (US 2019/0352796) teaches a Czochralski apparatus comprising a heat shield member 71 that guides gas (Fig 7; [0105]-[0114]).
WO 2011/034284 teaches a Czochralski crystal growth wherein a silicon single crystal is co-doped with nitrogen and carbon ([17]-[28], [47]-50]).
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