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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 09/08/2025 has been entered.
Priority
Applicant’s claim of foreign priority was acknowledged in the action dated 04/23/2024.
Response to Amendment
The amendment filed on 09/08/2025 has been entered. Claims 1, 4-8, and 10-11 are pending in the application. Applicant’s amendments to the claims have not introduced new matter and are supported in the specification in at least [0024], [0027], and Fig. 2 of the instant specification.
Response to Arguments
Applicant’s arguments, see Pg. 5-7 filed 09/08/2025 with respect to claim 8, have been fully considered however are solely directed to newly added claim limitations introduced in the amendment filed 09/08/2025, which postdates the limitations addressed in the final rejection mailed 09/16/2024.
Upon further search and consideration and as necessitated by the amendment, the 35 USC § 103 rejection of 06/10/2025 is withdrawn and a new grounds of rejection is made under 35 U.S.C. 103 as being unpatentable over Revankar et al. (US20120058022A1; cited in IDS dated 02/26/2024) in view of Park et al. (US10293326), Brinkman et al. (US20180290093A1), and Shibuya et al. (US20030106581A1), with evidentiary support provided by Special Metals (Incoloy Alloy 800H_800HT, 30 June 2002) as applied to the rejection of claim 8.
Applicant's remaining arguments filed 09/08/2025 have been fully considered but they are not persuasive.
In particular, Applicant asserts on Pg. 6-7 the effect of the invention is to provide a device for producing polycrystalline silicon, that the raw material gas is highly corrosive, and that the raw material gas needs to be purified of impurities present in the inner wall of the pipe, and that the filter is required to have a high filtration accuracy of not less than 90% with respect to particles having a particle diameter of not less than 0.3 µm.
Examiner notes Applicant’s assertion but also notes that 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).
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 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.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Revankar et al. (US20120058022A1; cited in IDS dated 02/26/2024) in view of Park et al. (US10293326), Brinkman et al. (US20180290093A1), and Shibuya et al. (US20030106581A1), with evidentiary support provided by Special Metals (Incoloy Alloy 800H_800HT, 30 June 2002) as applied to the rejection of claim 8.
Regarding claim 8, Revankar teaches a process for performing the chemical vapor deposition (CVD) of monosilane and hydrogen for the production of polysilicon ([0001]). Revankar teaches a process for performing CVD-Siemens reactions with a system that improves the recovery of unreacted silane and hydrogen and enables recycling of the reaction gases (Abstract; [0016]; [0025]). Revankar teaches silane and hydrogen are purified through a series of filters prior to recycling, where off gases containing unreacted silane, hydrogen, and various impurities are filtered using sintered stainless steel filter elements ([0017]-[0018]; [0047]). Revankar teaches the stainless steel filters capture particles generated via nucleation and provide gases that are not contaminated with dust, allowing further recycling and cost improvements ([0036]). Revankar teaches the filtration of the silane and hydrogen gas is performed with a filter having a pore size of 0.04 µm or less to trap any particulates that may have escaped from the adsorption beds ([0041]-[0044]; [0059]). A filter that has a pore size of 0.04 µm would necessarily only allow particles smaller than 0.04 µm to pass through the filter. As such, the filter of Revankar would remove particles of 4.00 µm at 100% efficiency and remove at least 90% of particles of 0.3 µm or greater. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. MPEP 2144.05 (I). In the instant case, the range taught by Revankar (filter having a pore size of 0.04 µm or less) overlaps with the claimed range (not less than 90% of impurities with a particle diameter not less than 0.3 µm; 100% filtration accuracy at removing particles with particle diameter 4.00 µm). Therefore, the range in Revankar renders obvious the claimed range.
Revankar further teaches the filtered hydrogen stream is recycled back to the reactor [5] ([0068]). Filtering the hydrogen reaction gas from particulates prior to sending the gas back to the reactor meets the limitation “the filter being provided at an inflow port in a feed channel for feeding the raw material gas into a reactor which contains the raw material gas”.
Revankar explicitly states that both the condensed silane gas (i.e. recovered unreacted silane raw material gas) [0039] and hydrogen can be re-circulated back to the reactor ([0044]; [0068]), where the gas can be recycled immediately ([0025]). Revankar teaches that the stainless steel filter (7) is present in-line with the reactor (5), from which unconverted reactions gases are recovered and can be resupplied to reactor (5) (Figure 1; Table 1; [0047]). Figure 1 from Revankar is reproduced below for convenience.
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[AltContent: textbox (Figure 1. Reproduced Figure 1 from Revankar showing the reactor (5) and the filter (7) are connected in a loop. )]Accordingly, as Revankar teaches a continuous process of recovering and re-circulating reaction gas with the step of filtering the raw gases with a stainless steel filter, the process step of “removing the impurity is carried out immediately before feeding the raw material gas into the reactor,” is taught by Revankar. In other words, filtering gas exiting a reactor and disclosing the gas can be recycled immediately ([0025]) is equivalent to filtering gas immediately before entering a reactor when the process is continuous, as is taught in Revankar.
The claim further requires the stainless steel filter contains “not less than 10% by mass of Ni.” Revankar makes obvious the use of a stainless steel filter but does not explicitly state the percent of Ni in the steel.
Park teaches a method to prepare polysilicon which includes a reactor and a source gas inlet (col. 2, lines 12-67), where the source gas includes trichlorosilane and hydrogen (col. 3, lines 4-6) and the reactor includes parts formed of Incoloy (800H, 800), stainless steel (SS316L, SS316), or Hastelloy (col. 6, lines 27-33). As evidenced by Special Metals, Incoloy alloys are composed of 30-35% by mass Ni (Table 1). Furthermore, the materials taught by Park are the same listed in the instant application as acceptable stainless steels with not less than 10% of Ni (Pg. 11, [0025]). In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. MPEP 2144.05 (I). In the instant case, the range taught by Park, as evidenced by Special Metals, (30-35% by mass Ni) overlaps with the claimed range (not less than 10% by mass Ni). Therefore, the range in Park, as evidenced by Special Metals, renders obvious the claimed range.
Advantageously, reactor parts fashioned from these materials do not affect the purity of the precipitated polysilicon, have high-temperature stability (1,000 °C or more), have corrosion resistance, and are cheap and easy to process (col. 6, lines 27-33).
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to fashion polysilicon synthesis reactors, and filter mesh grids, with stainless steel alloys, such as Incoloy, with 30-35% by mass Ni in the method of Revankar in order to not affect the purity of the polysilicon produced, provide a filter with high temperature stability and corrosion resistance, and implement a cheap and easy to process material, as taught by Park.
The claim further requires “wherein the filter is shaped such that a first end of the filter is open while a second end of the filter on a side opposite to the first end is closed and that a filter surface extends between the first end and the second end,” to which Revankar and Park are silent.
Brinkman teaches a plurality of filtration units for use in filtering impurities prior to performing silicon crystal growth where the filter units (17 and 27) have an inlet feed (38 and 40) and an pressure regulating outlet (45 and 47) that can be opened or closed ([0044]-[0045], [0049], [0056]-0058], Fig. 1). Brinkman teaches the inlet to the filter and the outlet to the filter are on opposite sides, where the filter is positioned between the two (see connection of 38 to 17 to 45 in Fig. 1 for example). Brinkman teaching a filter with openings on either side, where one side can be closed meets the limitation “a first end of the filter is open while a second end of the filter on a side opposite to the first end is closed and that a filter surface extends between the first end and the second end.”
Advantageously, providing a filter with an open end and an end that can be closed allows for control of the overall pressure of the gas being provided to the silicon growth reactor and ensures the pressure stays within the pressure limit of silicon growth ([0059]).
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to provide a filter with an opening and an closed end on opposite ends of a filter in the method of Revankar in order to enable control of the gas pressure exiting the filter to ensure the silicon growth process continues, as taught by Brinkman.
The claim further requires “wherein an outer periphery of the first end is fixed to an inner wall of the feed channel such that the first end and the second end are aligned along the inner wall of the feed channel,” to which Revankar, Park, and Brinkman are silent.
Shibuya teaches a process for producing silicon where a raw material gas supply (18) is supplied to a vaporizing chamber (14) which is then filtered through a stainless steel filter (26) that is positioned between the vaporizing chamber and the process chamber (11) where the silicon is made (Abstract; Fig. 1; [0036]-[0037]; [0044]). Shibuya clearly depicts in Fig. 1 the stainless steel filter is present within a unit that supplies the gas supply and that the stainless steel filter is fixed to either side of the channel such that it spans the length of the chamber and effectively separates the gas supply from the processing chamber (Fig. 1). The inlet gas line (18) and the vaporizing chamber can be viewed as a “feed channel” and is considered to meet this limitation. Fig. 1 from Shibuya is reproduced below for convenience.
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Figure 2. Reproduced Fig. 1 from Shibuya depicting the filter (26) attached to the walls of the unit and positioned between the vaporizer (14) and the processor
Advantageously, by dividing the vaporizing chamber that is supplying feed gas and the processing unit with a filter, a pressure differential is unlikely to be generated, which aids uniform generation of silicon ([0015]; [0044]).
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to provide a filter attached in-line, where the filter is positioned in a unit between the gas feed and the processing chamber, in the method of Revankar in order to limit pressure differentials to aid uniform silicon growth, as taught by Shibuya.
Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Revankar et al. (US20120058022A1; cited in IDS dated 02/26/2024) in view of Park et al. (US10293326), Brinkman et al. (US20180290093A1), and Shibuya et al. (US20030106581A1) and further in view of Wan et al. (CN102814084A English), with evidentiary support provided by Special Metals (Incoloy Alloy 800H_800HT, 30 June 2002) as applied to the rejection of claim 8.
Regarding claim 11, Revankar in view of Park, Brinkman and Shibuya teaches the process of claim 8 and the claim further requires “the filter has a cylindrical shape,” to which Revankar, Park, Brinkman, and Shibuya are silent.
Wan teaches a gas filtering apparatus used in polysilicon production that comprises a straight cylinder part where a gas inlet is positioned in the lower part, a gas filter is provided in the straight cylinder part that comprises through holes and a gas outlet positioned on the upper part of a filtering apparatus (Abstract; Claims 1, 2, 4; Fig. 1).
Advantageously, the cylindrical filters of Wan do not influence the quality of polycrystalline silicon in a negative way and are simple to form and low in cost (Abstract).
Thus, prior to the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to provide a filter comprising a straight cylinder part in the method of Revankar in order to utilize a filter that is simple to form and low in cost that does not negatively affect the quality of the polycrystalline silicon produced, as taught by Wan.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Jordan Wayne Taylor whose telephone number is (571)272-9895. The examiner can normally be reached Monday - Friday, 7:30 AM - 5 PM EST; Second Fridays Off.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Sally A. Merkling can be reached on (571)272-6297. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/J.W.T./Examiner, Art Unit 1738
/SALLY A MERKLING/SPE, Art Unit 1738