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 § 112
The following is a quotation of 35 U.S.C. 112(b):
(B) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-7 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor, or for pre-AIA the applicant regards as the invention.
Claim 1 recites the limitation "the single crystal" in l. 5. There is insufficient antecedent basis for this limitation in the claim. It is assumed applicants intended to refer to “the single crystal of silicon.” It is also assumed that the recitation of “the single crystal” in ll. 7, 13, 15, and 16 of claim 1 as well as in claims 2 and 6-7 should also be changed to “the single crystal of silicon” to correct for antecedent basis. Dependent claims 2-7 are similarly rejected due to their dependence on claim 1.
Claim 3 recites that the crucible is rotated “at a speed of less than 3.5 rpm and not more than 6.0 rpm.” However, if the rotation speed is less than 3.5 rpm then it already is not more than 6.0 rpm. Thus, it is unclear how the reference to being not more than 6.0 rpm is intended to further limit the claim. It is assumed that this is a typographical error and that applicants intended to recite that the rotational speed is “not less than 3.5 rpm.”
Claim Rejections - 35 USC § 103
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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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.
Claims 1 and 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Appl. Publ. No. 2004/0192015 to Von Ammon, et al. (hereinafter “Von Ammon”) in view of U.S. Patent Appl. Publ. No. 2011/0300371 to Omote, et al. (“Omote”) and further in view of U.S. Patent Appl. Publ. No. 2014/0374861 to Hoshi, et al. (“Hoshi”).
Regarding claim 1, Von Ammon teaches a method of producing an epitaxially coated semiconductor wafer from monocrystalline silicon (see the Abstract, Figs. 1-17, and entire reference which teach a method of growing a Si wafer by the Czochralski (CZ) method), the method comprising:
providing a melt of silicon in a crucible (see Fig. 14, ¶¶[0038]-[0050], and Example 1 at ¶¶[0057]-[0065] which teach providing a melt of Si in a crucible);
pulling of a single crystal of silicon from a surface of the melt with a pulling speed v by the CZ method (see Fig. 14, ¶¶[0038]-[0050], and Example 1 at ¶¶[0057]-[0065] which teach pulling a Si single crystal (1) from the melt at a pulling speed v by the CZ method),
wherein oxygen and boron are incorporated into the single crystal and a concentration of the oxygen in the single crystal is not less than 6.4×1017 atoms/cm3 and not more than 8.0×1017 atoms/cm3 (see ¶[0018] which teaches that the Si is doped with boron and has an oxygen concentration of 4×1017 to 7.2×1017 atoms/cm3), and
wherein there is no doping of the melt with nitrogen and carbon (see ¶[0018] which teaches that doping with carbon and nitrogen is optional which means that in at least one embodiment no carbon and nitrogen doping is provided);
applying a CUSP magnetic field to the melt during the pulling of the single crystal of silicon, surrounded by a heat shield (see Fig. 14, ¶¶[0038]-[0050], and Example 1 at ¶¶[0057]-[0065] which teach that a CUSP magnetic field is applied using a magnet (13) during crystal growth while the Si single crystal (1) is surrounded by a heat shield (18));
controlling the pulling speed v and an axial temperature gradient G at a phase boundary between the single crystal and the melt in such a way that a quotient v/G is not less than 0.13 mm2/°C min and not more than 0.20 mm2/°C min (see Fig. 2 and ¶[0039] which teach that the ratio v/G is preferably between approximately 1.2 to 1.4×10-3 cm2/K-min (i.e., 0.12 to 0.14 mm2/°C min) in order to produce a perfect Si single crystal);
heating of the single crystal by a ring-shaped heater, which is disposed above the melt and surrounds the single crystal (see Fig. 14, ¶¶[0038]-[0050], and Example 1 at ¶¶[0057]-[0065] which teach that the Si single crystal (1) is heated by a ring-shaped heater (19) which is disposed above the melt and surrounds the Si single crystal (1));
producing a substrate wafer from the monocrystalline silicon having a polished lateral face by processing the single crystal of silicon (see Example 1 at ¶¶[0057]-[0065] which teaches that a Si wafer is produced from the grown Si single crystal (1) which, as exemplified by at least ¶[0013], necessarily involves cutting and polishing the Si single crystal (1) to produce wafers which are suitable for the formation of electronic devices thereupon).
Von Ammon does not teach that a resistivity of the single crystal is not less than 10 mWcm and not more than 25 mWcm. However, in Figs. 1-2 and ¶¶[0028]-[0047] as well as elsewhere throughout the entire reference Omote teaches an analogous method of producing an epitaxial Si substrate (1) from a Si wafer grown by the Czochralski method. In ¶[0044] Mangelberger specifically teaches that in order to enhance the aggregation of oxygen precipitate it is preferable that the Si substrate (1) is a p+ substrate doped with boron such that the resistivity has a value in the overlapping range of 1.1 mW-cm to 100 mW-cm. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Omote and would be motivated to dope the Si ingot produced in the method of Von Ammon with boron in an amount sufficient to produce a resistivity in the overlapping range of 1.1 mW-cm to 100 mW-cm in order to enhance the aggregation of oxygen precipitates and thereby form a gettering sink within the substrate.
Von Ammon and Mangelberger do not teach depositing an epitaxial layer of silicon on the polished lateral face of the substrate wafer, wherein the depositing of the epitaxial layer is a first heat treatment in the course of which the substrate wafer is heated to a temperature of not less than 700 °C. However, in Figs. 1-3, ¶¶[0041]-[0060], and Example 1 at ¶[0062]-[0065], and Example 2 at ¶¶[0071]-[0074] Hoshi teaches an analogous method of growing a Si single crystal wafer by the CZ method followed by deposition of a Si epitaxial layer thereupon as part of a process for forming electronic devices. In Examples 1-2 Hoshi specifically teaches that epitaxial growth is accompanied by performing a heat treatment at 1,000 °C for 30 or 60 minutes in order to form oxide precipitates (BMDs) which function to capture impurities. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to perform a heat treatment at a temperature of greater than 700 °C and deposit an epitaxial layer thereupon in order to getter impurities and provide a clean and highly crystalline surface for the formation of electronic devices thereupon. The combination of prior art elements according to known methods to yield predictable results has been held to support a prima facie determination of obviousness. All the claimed elements are known in the prior art and one skilled in the art could combine the elements as claimed by known methods with no change in their respective functions, with the combination yielding nothing more than predictable results to one of ordinary skill in the art. KSR International Co. v. Teleflex Inc., 550 U.S. 398, __, 82 USPQ2d 1385, 1395 (2007). See also, MPEP 2143(A).
Regarding claim 7, Von Ammon teaches that the single crystal has a diameter of 300 mm (see ¶[0039] and Example 1 at ¶¶[0057]-[0065] which teach that the Si single crystal has a diameter of 300 mm), and a power of the ring-shaped heater is not less than 7 kW and not more than 13 kW (see ¶[0023] and ¶[0050] which teach that depending on the geometrical arrangement, heating powers in the range from 1 to 60 kW are required).
Claim 2 is/are rejected under 35 U.S.C. 103 as being unpatentable over Von Ammon in view of Omote and further in view of Hoshi and still further in view of U.S. Patent Appl. Publ. No. 2020/0149184 to Mangelberger, et al. (“Mangelberger”).
Regarding claim 2, Von Ammon, Omote, and Hoshi do not teach cooling of the single crystal pulled from the melt at a cooling rate within a temperature range from 1000 °C to 800 °C, which is not less than 0.7 °C/min and not more than 1 °C/min. However, in ¶¶[0033]-[0081] as well as elsewhere throughout the entire reference Mangelberger teaches an analogous method of producing high quality Si single crystals by the Czochralski method. In ¶[0068] Mangelberger specifically teaches that the single crystal should be cooled relatively slowly in the temperature range of 1,000 to 800 °C at a cooling rate of 0.5 to 1.2 °C/min in order to, for example, promote the creation and stabilization of BMD nuclei. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to cool the Si single crystal pulled from the melt in the method of Von Ammon, Omote, and Hoshi to the temperature range of 800 to 1,000 at a cooling rate of in the overlapping range of 0.5 to 1.2 °C/min in order to promote the creation and stabilization of BMD nuclei.
Claims 3 and 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Von Ammon in view of Omote and further in view of Hoshi and still further in view of U.S. Patent Appl. Publ. No. 2008/0153261 to Weber, et al. (“Weber”).
Regarding claim 3, Von Ammon does not teach that wherein a distance of a lower edge of the heat shield from the surface of the melt is not less than 35 mm and not more than 45 mm. However, in Fig. 4 and ¶¶[0019]-[0036] as well as elsewhere throughout the entire reference Weber teaches an analogous system and method for the growth of Si single crystals by the magnetic Czochralski method. In ¶[0036] Weber specifically teaches that the distance g between the lower edge of the heat shield (2) and the surface of the melt is preferably in the overlapping range of 10 to 50 mm in order to control thermal gradients at the melt-solid interface, including the ratio v/G such that a Si single crystal having the desired materials properties may be obtained. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Weber and would be motivated to maintain a gap of 35 to 40 mm between the heat shield and the surface of the melt in the method of Von Ammon, Omote, and Hoshi in order to control temperature gradients at the melt-solid interface to produce the desired materials properties in the grown Si single crystal.
Regarding claim 5, Von Ammon teaches rotating of the crucible at a speed of less than 3.5 rpm and not more than 6.0 rpm (see ¶[0026] of von Ammon which teaches that the crucible is rotated at a speed of at least 3 rpm which encompasses the claimed range; alternatively, see ¶[0026] of Weber which teaches that the crucible is preferably rotated in the overlapping range of 1 to 4 rpm in order to produce the desired thermal gradients and oxygen content within the melt).
Claim 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Von Ammon in view of Omote and further in view of Hoshi and still further in view of U.S. Patent Appl. Publ. No. 2020/0216975 to Basak, et al. (“Basak”).
Regarding claim 4, Von Ammon does not teach that the CUSP magnetic field attains a maximum field strength of not less than 105 mT and not more than 116 mT, and a plane of the CUSP magnetic field with a strength of 0 mT is not less than 30 mm and not more than 80 mm below the surface of the melt. However, in Figs. 1-8 and ¶¶[0030]-[0079] as well as elsewhere throughout the entire reference Basak teaches an analogous method of growing a Si single crystal by the Czochralski method using a CUSP magnetic field. In ¶[0066] Basak specifically teaches that the magnetic field strength is regulated in at least two stages in order to control the amount of oxygen that is incorporated into the growing crystal. During an intermediate stage the magnetic field strength is, for example, 0.02 to 0.05 Tesla (20 to 50 mT) at the edge of the crystal (27) at the melt-solid interface and 0.05 to 0.12 T (50 to 120 mT) at the wall of the crucible (10). During a late body growth stage the magnetic field strength is 0.03 to 0.075 Tesla (30 to 75 mT) and 0.075 to 0.18 Tesla (75 to 180 mT), respectively. Then in ¶[0076] Basak further teaches that the CUSP position is also regulated in order to control the flow of SiO from the crucible (10) to the crystal (27). Maintaining the CUSP position from 10 to 40 mm below the melt line (36) facilitates reducing the oxygen concentration. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would look to the teachings of Basak and would be motivated to utilize routine experimentation to determine the optimal maximum magnetic field strength and plane of 0 mT during crystal growth in the method of Von Ammon, Omote, and Hoshi, including within the claimed range of 105 to 116 mT and a location 30 to 80 mm below the surface of the melt, with the motivation for doing so being to produce the desired amount and type of stirring and, consequently, the desired oxygen concentration within the melt.
Claim 6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Von Ammon in view of Omote and further in view of Hoshi and still further in view of U.S. Patent Appl. Publ. No. 2010/0059861 to Mueller, et al. (“Mueller”).
Regarding claim 6, Von Ammon teaches that the pulling of the single crystal is in an atmosphere of purge gas (see at least ¶[0003] which teaches that an inert purge gas flows through the pulling system), but does not teach that the pressure is not less than 2500 Pa and not more than 8500 Pa. However, in Figs. 3-4 and ¶¶[0028]-[0048] as well as elsewhere throughout the entire reference Mueller teaches an analogous method of growing single crystal Si ingots by the Czochralski method under an applied magnetic field. In ¶[0036] Mueller specifically teaches that the flow rate and pressure of the purge gas can be used to control the amount of oxygen incorporated into the melt and, consequently, into the grown Si single crystal with a pressure in the overlapping range of 1 to 4 kPa being preferred. Thus, a person of ordinary skill in the art prior to the effective filing date of the invention would be motivated to utilize a purge gas pressure in the overlapping range of 1 to 4 kPa during crystal growth in the method of Von Ammon, Omote, and Hoshi in order to control the incorporated oxygen content to the desired level.
Conclusion
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/KENNETH A BRATLAND JR/Primary Examiner, Art Unit 1714