US20160258684A1 - Purification of a metalloid by consumable electrode vacuum arc remelt process - Google Patents

Purification of a metalloid by consumable electrode vacuum arc remelt process Download PDF

Info

Publication number
US20160258684A1
US20160258684A1 US15/155,045 US201615155045A US2016258684A1 US 20160258684 A1 US20160258684 A1 US 20160258684A1 US 201615155045 A US201615155045 A US 201615155045A US 2016258684 A1 US2016258684 A1 US 2016258684A1
Authority
US
United States
Prior art keywords
cevar
ingot
short
crucible
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US15/155,045
Inventor
Raymond J. Roberts
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Consarc Corp
Original Assignee
Consarc Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Consarc Corp filed Critical Consarc Corp
Priority to US15/155,045 priority Critical patent/US20160258684A1/en
Assigned to CONSARC CORPORATION reassignment CONSARC CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ROBERTS, RAYMOND J.
Publication of US20160258684A1 publication Critical patent/US20160258684A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/08—Details peculiar to crucible or pot furnaces
    • F27B14/14—Arrangements of heating devices
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/037—Purification
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/003—Heating or cooling of the melt or the crystallised material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/06—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/06—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat
    • F27B2014/068—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat with the use of an electrode producing a current in the melt
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Definitions

  • the present invention relates to production of a purified metalloid such as silicon by a consumable electrode vacuum arc remelt process.
  • High purity silicon is needed for many kinds of electronic components such as silicon transistors, silicon integrated circuits and silicon solar cells. Since the invention of the first silicon transistor, many processes have been developed for producing silicon having the required purity levels.
  • CEVAR consumable electrode vacuum arc remelt
  • 2010/0154475 A1 discloses a primary silicon purification process with similarities to the Kroll purification process of titanium with brief mention of a secondary silicon composition purification process that involves high temperature vacuum melting of a silicon composition that comprises a boron and phosphorus doped silicon with silicon purity in the range of 99.99 percent to 99.9999 percent.
  • the CEVAR process produces a purified metal by these four steps: (1) evaporating impurities as the metal electrode is melted and exposed to a vacuum in the CEVAR furnace; (2) floating out of the liquid (melted) metal impurities that have a lower density than the metal electrode being melted; (3) dissociating molecular impurities by exposing them to the high energy plasma in the arc zone between the lower end of the electrode and the pool of molten (liquid) metal above the ingot being formed; and (4) solidification segregation, which results in impurity levels in the solidified metal of the ingot being lower for certain elements than the impurity levels in the adjacent liquid metal from which the solid ingot is being formed.
  • a room temperature metal electrode is charged into the CEVAR furnace, which is then evacuated to a vacuum.
  • a high magnitude direct current (DC current) arc is then struck between the lower end of the electrode and the CEVAR water-cooled crucible. The arc causes the lower end of the electrode to melt, whereupon the molten metal falls into the closed bottom crucible, where it solidifies and then cools, to form a purified ingot.
  • DC current direct current
  • the process is not known to be used to purify a metalloid such as silicon. Since silicon is a semiconductor and not a metal in its relatively pure state (though in need of further purification for the above-mentioned end uses), it has a relatively high electrical resistivity at or near room temperature. In fact, a silicon electrode sufficiently pure to be a candidate for purification by the CEVAR process, would have an electrical resistance that is far too high to permit the passage of such a high arc current at any reasonable applied voltage when it is at or near room temperature.
  • the metal of the solidified ingot formed in the conventional CEVAR process is initially at its solidus temperature and then cools progressively within the water cooled crucible, with the edges of the ingot cooling more rapidly than the center due to the proximity of the edges to the adjacent water cooled wall of the crucible. This generates stresses in the ingot due to differential thermal contraction, a process that puts the ingot surface in tension and the center in compression. For the metals usually melted by the CEVAR process this is not a problem, since they are relatively ductile, that is, resistant to cracking. However, in the case of any conventional CEVAR process that is used to melt silicon, which is brittle over a wide range of temperatures, such an ingot would be prone to undesirable cracking.
  • the present invention is an apparatus for producing an ingot of a purified metalloid such as silicon.
  • a silicon electrode is formed from one or more pieces of silicon.
  • the silicon electrode is preheated to a temperature at which it becomes sufficiently conductive to pass current in a subsequent CEVAR purification processing step without excessive voltage drop and cracking of the electrode, and then melted in a CEVAR purification process that includes a short CEVAR open-bottomed and water-cooled crucible.
  • the hot ingot resulting from the CEVAR process passes into a heating system adjacent to the open-bottom of the short CEVAR opened-bottomed crucible while the ingot is still hot, with the heating system being controlled to prevent cracking of the silicon ingot as it cools.
  • the present invention is a metalloid purification CEVAR furnace system that includes a short CEVAR open-bottomed crucible having means to contain the arc zone in a CEVAR purification process.
  • a heating system is provided adjacent to the open bottom of the short CEVAR open-bottomed crucible, and the heating system has means to provide controlled cooling of a hot ingot formed in the short CEVAR opened-bottomed crucible to prevent cracking of the ingot as it cools.
  • An ingot withdrawal drive system is provided to withdraw the ingot from the crucible at a rate equal to its vertical growth rate during steady state of the CEVAR purification process, such that the arc zone and the top of the solidified ingot remain within the CEVAR crucible.
  • a crucible/heater drive system can be provided to lift the short CEVAR opened-bottom crucible, the electrode and the heater that provides a temperature-controlled thermal environment for the hot ingot as the ingot remains stationary.
  • FIG. 1 is a simplified cross sectional view of one example of a CEVAR furnace system of the present invention.
  • the initial process step is pre-heating of the silicon electrode that is to be used in the CEVAR process.
  • the resistivity of silicon drops rapidly with increase in temperature, so a silicon electrode that has been preheated to a sufficiently high temperature, while remaining below its melting temperature so that it stays a solid (a necessary condition for the CEVAR melting process), will permit the passage of sufficient arc current to allow the CEVAR process to be started.
  • the required preheat temperature for the electrode in a particular CEVAR melting process can be designated the CEVAR process resistivity as determined by the process parameters for the particular CEVAR melting process. Such a preheat temperature would need to be at least several hundreds of degrees Centigrade. Additionally increasing the electrode's preheat temperature reduces the initial voltage drop in the electrode, so it permits the use of a lower voltage, less-expensive power supply.
  • Preheating of the electrode may be accomplished either within the CEVAR furnace or externally.
  • External heating for example in a resistance furnace having a vacuum or inert gas (controlled) atmosphere, may result in pickup of oxygen and nitrogen at the electrode surface as the electrode is transferred in air to the CEVAR furnace, with risk of increasing the impurity level of the subsequent CEVAR ingot.
  • a vacuum lock chamber may be provided between an external furnace chamber and the CEVAR furnace to establish a controlled environment without exposing the electrode to air during the transfer.
  • the passage of arc current in the CEVAR process can be used to maintain the electrode's temperature, or an auxiliary electrode heating system internal to the CEVAR furnace may be used to maintain the electrode's temperature during the CEVAR process. In either case, it is advantageous to provide thermal insulation within the CEVAR furnace around the electrode to decrease the energy consumed during the process.
  • a carbon fiber thermal insulating material can be used to at least partially surround the electrode in the CEVAR furnace.
  • a short CEVAR crucible (used in the CEVAR furnace) is preferably used that has an interior height, h, somewhere in the range of the diameter, d, of the ingot that is formed in the crucible; for example, the interior height of the short CEVAR crucible can be greater than 60 percent of the diameter of the formed silicon ingot and less than 120 percent of the diameter of the formed silicon ingot.
  • the interior height of the crucible is somewhere in the range of the length of a rectangular side of the ingot that is formed in the crucible; for example, the interior height of a rectangular short CEVAR crucible can be greater than 60 percent of the rectangular side of the formed silicon ingot and less than 120 percent of the rectangular side of the formed silicon ingot. In a conventional CEVAR process with a closed-bottom crucible, the interior height of the crucible would be much greater than the height of the ingot as disclosed, for example, in U.S. Pat. No. 4,131,754 (Roberts).
  • the CEVAR purification process utilized in the present invention is generally similar to that described, for example, in the above disclosed prior art except for preheat of the silicon electrode used in the CEVAR process and the use of a short CEVAR open-bottomed, water-cooled metal crucible as disclosed herein.
  • the preheated silicon electrode is placed in a short CEVAR open-bottomed crucible within the CEVAR furnace that is made gas-tight and brought to a vacuum or an otherwise controlled environment.
  • direct current (DC current) flowing through the electrode and the melt formed below the electrode establishes an arc between the lower end of electrode and the top of the melt with the arc zone remaining within the height of the short CEVAR opened-bottom crucible so that a hot (at a temperature elevated above room temperature) solidified ingot exits the bottom of the short CEVAR opened-bottom crucible.
  • Further controlled cooling of the hot solidified ingot exiting from the short CEVAR opened-bottom crucible is, as further described below, performed to substantially avoid cracking of the solidified ingot.
  • the ingot is withdrawn from the short CEVAR crucible into a heater system that provides controlled cooling over the temperature range in which the ingot is likely to crack.
  • the ingot withdrawal rate is essentially matched to the ingot growth rate during steady state operation, so that the arc zone and the top of the ingot remain within the crucible.
  • the ingot is kept stationary and the crucible, electrode and the crucible's exit heater are raised together, to essentially match the growth rate of the ingot.
  • the following process steps are performed: (1) forming an electrode from one or more pieces of silicon; (2) preheating the electrode to a temperature (by way of example and not limitation, between 800 and 1200 degrees Centigrade) at which it becomes sufficiently conductive (with a CEVAR process resistivity) to pass current in a subsequent CEVAR processing step without excessive voltage drop and prevention of cracking of the electrode; (3) melting the electrode by a CEVAR process; (4) causing the resulting hot ingot to pass into a heating system adjacent to the open-bottomed CEVAR crucible while the ingot is at a sufficiently elevated temperature to prevent cracking; and (5) controlling the heating system so as to prevent cracking of the silicon ingot as it cools.
  • the above preheating process step (2) may be performed within the CEVAR furnace or external to the furnace as described above.
  • the above melting of the electrode may include the process step of thermally insulating the electrode while the melting step is performed.
  • FIG. 1 illustrates one example of a CEVAR furnace system 10 of the present invention.
  • a DC circuit is formed between electrode 90 and short CEVAR opened-bottom crucible 12 with conductors 92 and 94 diagrammatically illustrating the connection to an external DC POWER SOURCE.
  • Electrode 94 (typically the positive potential electrode) is electrically connected to base 32 (or alternatively drive actuator 34 ).
  • FIG. 1 the CEVAR furnace system 10 is shown in mid (steady state) CEVAR melting process with a hot solidified ingot 96 partially formed within the crucible's interior height.
  • a pool of molten (liquid) metal 98 on the top of the ingot is formed as fused droplets of metal fall from the preheated electrode 90 through arc zone AZ.
  • a heating system is provided adjacent to the open bottom of the short CEVAR opened-bottom crucible, with the heating system providing controlled cooling of the ingot formed in the crucible so as to prevent cracking of the ingot.
  • the heating system includes ingot heater 22 that surrounds the hot ingot exiting the opened-bottom crucible and ingot heater controller 24 that provides a temperature-controlled thermal environment for the ingot as it passes through the ingot heater.
  • the temperature-controlled thermal environment is provided to allow controlled conductive heating into the interior of the ingot (sometimes referred to as heat “soaking”) and controlled thermal radiation from the exterior surfaces of the ingot as the ingot cools so that cracking can be avoided.
  • the gas-tight CEVAR furnace chamber 11 is diagrammatically illustrated in FIG. 1 with dashed lines and includes a gas tight seal for drive actuator 34 , which is further described below.
  • An ingot withdrawal drive system can be provided to withdraw the solidified ingot at a rate substantially equal to its vertical growth rate during steady state CEVAR process operation, such that the arc zone and the top of the solidified ingot remain within the crucible, or alternatively, a drive system can be provided that lifts the crucible, electrode and ingot heater while the solidified ingot remains stationary. At the beginning and end of the CEVAR purification process the ingot withdrawal rate will vary due to transient startup and end process parameters. As shown in FIG. 1 the ingot withdrawal drive system can include base 32 upon which the bottom of the solidified ingot sits and drive actuator 34 that controls the rate of withdrawal (drop) of the ingot from the crucible in the downward direction.
  • Base 32 can be configured with a contour that enhances interlocking contact with the bottom of the solidified ingot.
  • base 32 is configured with a dovetail interface with the bottom of solidified ingot 96 . This is advantageous if the solidified ingot side wall develops a resistance contact with the interior side wall of the short CEVAR opened-bottom crucible since drive actuator 34 can pull down the base with interlocked solidified ingot in opposition to the side wall resistance.
  • an electrode drive system (not shown in the figure) is provided to lower the preheated silicon electrode as its lower end is melted and drips off of the electrode during the CEVAR purification process.
  • the shape of the formed silicon ingot, and therefore the interior wall shape of the short CEVAR opened-bottom crucible may be of various cross sectional configurations, including cylindrical or rectangular, and with or without an upward tapering inner diameter or perimeter to facilitate downward movement of the ingot as the hot solid ingot is formed.
  • continuous charging of the CEVAR furnace with preheated electrodes can be performed so that the resulting continuous ingot is formed from a succession of multiple preheated electrodes.
  • an ingot cut-off apparatus can be provided to cut off sections of the resulting continuous ingot for removal of ingot sections as the continuous CEVAR purification process continues.
  • the word “Vacuum” in CEVAR means melting at any level of pressure below one atmosphere.
  • the melting may be advantageously conducted at atmospheric pressure or even above, in an inert gas atmosphere, and such “pressure arc melting” of silicon is within the scope of the present invention.

Abstract

A metalloid such as silicon in the form of a preheated solid electrode is purified by a CEVAR purification process by producing an ingot with controlled heating and cool down after the preheated electrode is melted in a CEVAR furnace system using a short CEVAR open-bottomed crucible.

Description

    CROSS REFERENCE TO RELATED APPLICATIONS
  • This is a divisional application of application Ser. No. 13/586,149, filed Aug. 15, 2012, which application claims the benefit of U.S. Provisional Application No. 61/527,799 filed Aug. 26, 2011, both of which applications are hereby incorporated herein by reference in their entireties.
    • FIELD OF THE INVENTION
  • The present invention relates to production of a purified metalloid such as silicon by a consumable electrode vacuum arc remelt process.
    • BACKGROUND OF THE INVENTION
  • High purity silicon is needed for many kinds of electronic components such as silicon transistors, silicon integrated circuits and silicon solar cells. Since the invention of the first silicon transistor, many processes have been developed for producing silicon having the required purity levels.
  • A process that has been used for producing high quality metals such as steels, nickel-based superalloys, titanium etc. is known as a consumable electrode vacuum arc remelt (CEVAR) process. See, for example, U.S. Pat. No. 3,187,079 (Pestel); U.S. Pat. No. 3,344,840 (Buehl et al.); U.S. Pat. No. 3,480,716 (Lynch et al.); U.S. Pat. No. 4,303,797 (Roberts); U.S. Pat. No. 4,569,056 (Veil, Jr.); and United States Patent Application Publication No. 2008/0142188 A1 (Ishigami) for various technical aspects of the CEVAR process, all of which publications are incorporated herein in their entireties by reference. The CEVAR process is differentiated from a non-consumable electrode vacuum arc remelt where a non-consumable electrode, for example a graphite or tungsten electrode, is used to melt titanium or zirconium, for example, as disclosed in U.S. Pat. No. 3,546,348 (DeCorso). United States Patent Application Publication No. 2010/0154475 A1 (Matheson et al.) discloses a primary silicon purification process with similarities to the Kroll purification process of titanium with brief mention of a secondary silicon composition purification process that involves high temperature vacuum melting of a silicon composition that comprises a boron and phosphorus doped silicon with silicon purity in the range of 99.99 percent to 99.9999 percent.
  • Generally the CEVAR process produces a purified metal by these four steps: (1) evaporating impurities as the metal electrode is melted and exposed to a vacuum in the CEVAR furnace; (2) floating out of the liquid (melted) metal impurities that have a lower density than the metal electrode being melted; (3) dissociating molecular impurities by exposing them to the high energy plasma in the arc zone between the lower end of the electrode and the pool of molten (liquid) metal above the ingot being formed; and (4) solidification segregation, which results in impurity levels in the solidified metal of the ingot being lower for certain elements than the impurity levels in the adjacent liquid metal from which the solid ingot is being formed.
  • In the usual CEVAR process a room temperature metal electrode is charged into the CEVAR furnace, which is then evacuated to a vacuum. A high magnitude direct current (DC current) arc is then struck between the lower end of the electrode and the CEVAR water-cooled crucible. The arc causes the lower end of the electrode to melt, whereupon the molten metal falls into the closed bottom crucible, where it solidifies and then cools, to form a purified ingot.
  • Despite the ability of the CEVAR process to purify various metals, the process is not known to be used to purify a metalloid such as silicon. Since silicon is a semiconductor and not a metal in its relatively pure state (though in need of further purification for the above-mentioned end uses), it has a relatively high electrical resistivity at or near room temperature. In fact, a silicon electrode sufficiently pure to be a candidate for purification by the CEVAR process, would have an electrical resistance that is far too high to permit the passage of such a high arc current at any reasonable applied voltage when it is at or near room temperature.
  • The metal of the solidified ingot formed in the conventional CEVAR process is initially at its solidus temperature and then cools progressively within the water cooled crucible, with the edges of the ingot cooling more rapidly than the center due to the proximity of the edges to the adjacent water cooled wall of the crucible. This generates stresses in the ingot due to differential thermal contraction, a process that puts the ingot surface in tension and the center in compression. For the metals usually melted by the CEVAR process this is not a problem, since they are relatively ductile, that is, resistant to cracking. However, in the case of any conventional CEVAR process that is used to melt silicon, which is brittle over a wide range of temperatures, such an ingot would be prone to undesirable cracking.
  • It is one object of the present invention to provide apparatus and method for purification of a metalloid such as silicon that includes a CEVAR furnace and process.
    • BRIEF SUMMARY OF THE INVENTION
  • In one aspect the present invention is an apparatus for producing an ingot of a purified metalloid such as silicon. A silicon electrode is formed from one or more pieces of silicon. The silicon electrode is preheated to a temperature at which it becomes sufficiently conductive to pass current in a subsequent CEVAR purification processing step without excessive voltage drop and cracking of the electrode, and then melted in a CEVAR purification process that includes a short CEVAR open-bottomed and water-cooled crucible. The hot ingot resulting from the CEVAR process passes into a heating system adjacent to the open-bottom of the short CEVAR opened-bottomed crucible while the ingot is still hot, with the heating system being controlled to prevent cracking of the silicon ingot as it cools.
  • In another aspect the present invention is a metalloid purification CEVAR furnace system that includes a short CEVAR open-bottomed crucible having means to contain the arc zone in a CEVAR purification process. A heating system is provided adjacent to the open bottom of the short CEVAR open-bottomed crucible, and the heating system has means to provide controlled cooling of a hot ingot formed in the short CEVAR opened-bottomed crucible to prevent cracking of the ingot as it cools. An ingot withdrawal drive system is provided to withdraw the ingot from the crucible at a rate equal to its vertical growth rate during steady state of the CEVAR purification process, such that the arc zone and the top of the solidified ingot remain within the CEVAR crucible. Alternatively a crucible/heater drive system can be provided to lift the short CEVAR opened-bottom crucible, the electrode and the heater that provides a temperature-controlled thermal environment for the hot ingot as the ingot remains stationary.
  • The above and other aspects of the invention are set forth in this specification and the appended claims.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • The figures, in conjunction with the specification and claims, illustrate one or more non-limiting modes of practicing the invention. The invention is not limited to the illustrated layout and content of the drawings.
  • FIG. 1 is a simplified cross sectional view of one example of a CEVAR furnace system of the present invention.
    •  DETAILED DESCRIPTION OF THE INVENTION
  • In the present invention of producing a silicon ingot from a silicon electrode in a CEVAR purification process, the initial process step is pre-heating of the silicon electrode that is to be used in the CEVAR process. The resistivity of silicon drops rapidly with increase in temperature, so a silicon electrode that has been preheated to a sufficiently high temperature, while remaining below its melting temperature so that it stays a solid (a necessary condition for the CEVAR melting process), will permit the passage of sufficient arc current to allow the CEVAR process to be started. The required preheat temperature for the electrode in a particular CEVAR melting process can be designated the CEVAR process resistivity as determined by the process parameters for the particular CEVAR melting process. Such a preheat temperature would need to be at least several hundreds of degrees Centigrade. Additionally increasing the electrode's preheat temperature reduces the initial voltage drop in the electrode, so it permits the use of a lower voltage, less-expensive power supply.
  • Preheating of the electrode may be accomplished either within the CEVAR furnace or externally. External heating, for example in a resistance furnace having a vacuum or inert gas (controlled) atmosphere, may result in pickup of oxygen and nitrogen at the electrode surface as the electrode is transferred in air to the CEVAR furnace, with risk of increasing the impurity level of the subsequent CEVAR ingot. Optionally a vacuum lock chamber may be provided between an external furnace chamber and the CEVAR furnace to establish a controlled environment without exposing the electrode to air during the transfer.
  • As the heated electrode is melted in the CEVAR furnace, the passage of arc current in the CEVAR process can be used to maintain the electrode's temperature, or an auxiliary electrode heating system internal to the CEVAR furnace may be used to maintain the electrode's temperature during the CEVAR process. In either case, it is advantageous to provide thermal insulation within the CEVAR furnace around the electrode to decrease the energy consumed during the process. For example a carbon fiber thermal insulating material can be used to at least partially surround the electrode in the CEVAR furnace.
  • In the present invention, a short CEVAR crucible (used in the CEVAR furnace) is preferably used that has an interior height, h, somewhere in the range of the diameter, d, of the ingot that is formed in the crucible; for example, the interior height of the short CEVAR crucible can be greater than 60 percent of the diameter of the formed silicon ingot and less than 120 percent of the diameter of the formed silicon ingot. Alternatively if the cross section of the interior wall of the short CEVAR crucible is rectangular in shape, the interior height of the crucible is somewhere in the range of the length of a rectangular side of the ingot that is formed in the crucible; for example, the interior height of a rectangular short CEVAR crucible can be greater than 60 percent of the rectangular side of the formed silicon ingot and less than 120 percent of the rectangular side of the formed silicon ingot. In a conventional CEVAR process with a closed-bottom crucible, the interior height of the crucible would be much greater than the height of the ingot as disclosed, for example, in U.S. Pat. No. 4,131,754 (Roberts).
  • The CEVAR purification process utilized in the present invention is generally similar to that described, for example, in the above disclosed prior art except for preheat of the silicon electrode used in the CEVAR process and the use of a short CEVAR open-bottomed, water-cooled metal crucible as disclosed herein. Generally for the present invention, during the CEVAR purification process, the preheated silicon electrode is placed in a short CEVAR open-bottomed crucible within the CEVAR furnace that is made gas-tight and brought to a vacuum or an otherwise controlled environment. During the process, direct current (DC current) flowing through the electrode and the melt formed below the electrode establishes an arc between the lower end of electrode and the top of the melt with the arc zone remaining within the height of the short CEVAR opened-bottom crucible so that a hot (at a temperature elevated above room temperature) solidified ingot exits the bottom of the short CEVAR opened-bottom crucible. Further controlled cooling of the hot solidified ingot exiting from the short CEVAR opened-bottom crucible is, as further described below, performed to substantially avoid cracking of the solidified ingot.
  • The ingot is withdrawn from the short CEVAR crucible into a heater system that provides controlled cooling over the temperature range in which the ingot is likely to crack. The ingot withdrawal rate is essentially matched to the ingot growth rate during steady state operation, so that the arc zone and the top of the ingot remain within the crucible. In an alternative arrangement of the present invention, the ingot is kept stationary and the crucible, electrode and the crucible's exit heater are raised together, to essentially match the growth rate of the ingot.
  • In practice of one embodiment of the present invention, the following process steps are performed: (1) forming an electrode from one or more pieces of silicon; (2) preheating the electrode to a temperature (by way of example and not limitation, between 800 and 1200 degrees Centigrade) at which it becomes sufficiently conductive (with a CEVAR process resistivity) to pass current in a subsequent CEVAR processing step without excessive voltage drop and prevention of cracking of the electrode; (3) melting the electrode by a CEVAR process; (4) causing the resulting hot ingot to pass into a heating system adjacent to the open-bottomed CEVAR crucible while the ingot is at a sufficiently elevated temperature to prevent cracking; and (5) controlling the heating system so as to prevent cracking of the silicon ingot as it cools.
  • In alternative examples of the invention, the above preheating process step (2) may be performed within the CEVAR furnace or external to the furnace as described above.
  • In alternative examples of the invention, the above melting of the electrode may include the process step of thermally insulating the electrode while the melting step is performed.
  • FIG. 1 illustrates one example of a CEVAR furnace system 10 of the present invention. A DC circuit is formed between electrode 90 and short CEVAR opened-bottom crucible 12 with conductors 92 and 94 diagrammatically illustrating the connection to an external DC POWER SOURCE. Electrode 94 (typically the positive potential electrode) is electrically connected to base 32 (or alternatively drive actuator 34).
  • In FIG. 1 the CEVAR furnace system 10 is shown in mid (steady state) CEVAR melting process with a hot solidified ingot 96 partially formed within the crucible's interior height. A pool of molten (liquid) metal 98 on the top of the ingot is formed as fused droplets of metal fall from the preheated electrode 90 through arc zone AZ. A heating system is provided adjacent to the open bottom of the short CEVAR opened-bottom crucible, with the heating system providing controlled cooling of the ingot formed in the crucible so as to prevent cracking of the ingot. The heating system includes ingot heater 22 that surrounds the hot ingot exiting the opened-bottom crucible and ingot heater controller 24 that provides a temperature-controlled thermal environment for the ingot as it passes through the ingot heater. The temperature-controlled thermal environment is provided to allow controlled conductive heating into the interior of the ingot (sometimes referred to as heat “soaking”) and controlled thermal radiation from the exterior surfaces of the ingot as the ingot cools so that cracking can be avoided.
  • The gas-tight CEVAR furnace chamber 11 is diagrammatically illustrated in FIG. 1 with dashed lines and includes a gas tight seal for drive actuator 34, which is further described below.
  • An ingot withdrawal drive system can be provided to withdraw the solidified ingot at a rate substantially equal to its vertical growth rate during steady state CEVAR process operation, such that the arc zone and the top of the solidified ingot remain within the crucible, or alternatively, a drive system can be provided that lifts the crucible, electrode and ingot heater while the solidified ingot remains stationary. At the beginning and end of the CEVAR purification process the ingot withdrawal rate will vary due to transient startup and end process parameters. As shown in FIG. 1 the ingot withdrawal drive system can include base 32 upon which the bottom of the solidified ingot sits and drive actuator 34 that controls the rate of withdrawal (drop) of the ingot from the crucible in the downward direction. Base 32 can be configured with a contour that enhances interlocking contact with the bottom of the solidified ingot. For example as shown in FIG. 1 base 32 is configured with a dovetail interface with the bottom of solidified ingot 96. This is advantageous if the solidified ingot side wall develops a resistance contact with the interior side wall of the short CEVAR opened-bottom crucible since drive actuator 34 can pull down the base with interlocked solidified ingot in opposition to the side wall resistance.
  • As in a conventional CEVAR furnace, an electrode drive system (not shown in the figure) is provided to lower the preheated silicon electrode as its lower end is melted and drips off of the electrode during the CEVAR purification process.
  • By way of example and not of limitation, for a 200 cm long and 30 cm diameter silicon electrode that is to be melted at 7,000 amperes DC in a CEVAR purification process of the present invention, it may be desirable to limit the initial voltage drop in the electrode to 5 volts DC since this is a moderate value in comparison to the typical CEVAR process arc voltage within the range of 20 to 40 volts DC (as a function of pressure within the CEVAR furnace). In such an example, conventional calculations indicate that the silicon electrode would require preheating to a temperature that results in a silicon resistivity of 2,524 microhm-cm (CEVAR process resistivity) of the electrode. The temperature needed to achieve this CEVAR process resistivity would depend on the types and levels of impurities in the silicon electrode used in a particular application of the present invention with the temperature increasing as the silicon purity of the silicon electrode increases.
  • The shape of the formed silicon ingot, and therefore the interior wall shape of the short CEVAR opened-bottom crucible, may be of various cross sectional configurations, including cylindrical or rectangular, and with or without an upward tapering inner diameter or perimeter to facilitate downward movement of the ingot as the hot solid ingot is formed.
  • In some examples of the invention, continuous charging of the CEVAR furnace with preheated electrodes can be performed so that the resulting continuous ingot is formed from a succession of multiple preheated electrodes. In these examples, an ingot cut-off apparatus can be provided to cut off sections of the resulting continuous ingot for removal of ingot sections as the continuous CEVAR purification process continues.
  • In the above examples of the invention, the word “Vacuum” in CEVAR means melting at any level of pressure below one atmosphere.
  • In other examples of the invention, the melting may be advantageously conducted at atmospheric pressure or even above, in an inert gas atmosphere, and such “pressure arc melting” of silicon is within the scope of the present invention.
  • The present invention has been described in terms of preferred examples and embodiments. Equivalents, alternatives and modifications, aside from those expressly stated, are possible and within the scope of the invention. Those skilled in the art, having the benefit of the teachings of this specification, may make modifications thereto without departing from the scope of the invention.

Claims (20)

1. A CEVAR furnace system for producing a purified silicon ingot from a silicon electrode, the CEVAR furnace system comprising:
a silicon electrode heating apparatus for preheating the silicon electrode to form a preheated silicon electrode;
a gas-tight CEVAR furnace chamber;
a short CEVAR open-bottomed crucible for containment of an arc zone from a CEVAR purification process melting the preheated silicon electrode, the short CEVAR open-bottomed crucible disposed in the gas-tight CEVAR furnace chamber;
a preheated silicon electrode drive system for lowering the preheated silicon electrode within the short CEVAR open-bottomed crucible as a lower end of the preheated silicon electrode melts in the CEVAR purification process;
an ingot heating apparatus disposed adjacent to the open bottom of the short CEVAR open-bottomed crucible through which the purified silicon ingot formed in the CEVAR purification process passes;
an ingot heating controller for controlling the ingot heating apparatus to provide a temperature-controlled thermal environment for the purified silicon ingot passing through the ingot heating apparatus; and
an ingot withdrawal drive system for alternatively withdrawing the purified silicon ingot from the short CEVAR open-bottomed crucible at a vertical growth rate of the purified silicon ingot during steady state of the CEVAR purification process or raising the short CEVAR open-bottomed crucible, the silicon electrode and the ingot heating apparatus at the vertical growth rate of the purified silicon ingot during steady state of the CEVAR purification process.
2. The CEVAR furnace system of claim 1 wherein an interior height of the short CEVAR opened-bottom crucible is at least 60 percent and less than 120 percent of a diameter of the purified silicon ingot formed in the CEVAR purification process.
3. The CEVAR furnace system of claim 1 further comprising a vacuum lock chamber connected between the silicon electrode heating apparatus and the short CEVAR opened-bottom crucible in the gas-tight CEVAR furnace chamber to prevent exposure to air of the preheated silicon electrode during transfer from the silicon electrode heating apparatus to the gas-tight CEVAR furnace chamber.
4. The CEVAR furnace system of claim 3 wherein the silicon electrode heating apparatus comprises a resistance furnace.
5. The CEVAR furnace system of claim 1 further comprising an auxiliary electrode heater disposed within the gas-tight CEVAR furnace chamber to heat the preheated silicon electrode during the CEVAR purification process.
6. The CEVAR furnace system of claim 1 further comprising a thermal insulation disposed around the preheated silicon electrode in the gas-tight CEVAR furnace chamber.
7. The CEVAR furnace system of claim 6 wherein the thermal insulation comprises a carbon fiber insulating material.
8. The CEVAR furnace system of claim 1, the base having a contour for interlocking contact with the bottom of the purified silicon ingot.
9. The CEVAR furnace system of claim 1, the short CEVAR opened-bottom crucible having an interior wall with a rectangular cross section, the interior height of the short CEVAR opened-bottom crucible being at least 60 percent and less than 120 percent of the length of a rectangular side of the purified silicon ingot formed in the CEVAR purification process.
10. The CEVAR furnace system of claim 1, the ingot withdrawal drive system further comprising a base upon which the bottom of the purified silicon ingot sits and a drive actuator connected to the base to control the rate of withdrawing of the purified silicon ingot from the short CEVAR open-bottomed crucible.
11. The CEVAR furnace system of claim 10 further comprising a DC power source having a first output and a second output connected respectively between the preheated silicon electrode and the base or the drive actuator.
12. The CEVAR furnace system of claim 1 further comprising a continuous preheated silicon electrode furnace charging apparatus for forming the purified silicon ingot with the CEVAR furnace system as a continuous purified silicon ingot.
13. A CEVAR furnace system for producing a purified silicon ingot from a silicon electrode, the CEVAR furnace system comprising:
a gas-tight CEVAR furnace chamber;
a silicon electrode heating apparatus disposed within the gas-tight CEVAR furnace chamber for preheating the silicon electrode to form a preheated silicon electrode;
a short CEVAR open-bottomed crucible for containment of an arc zone from a CEVAR purification process melting the preheated silicon electrode, the short CEVAR open-bottomed crucible disposed in the gas-tight CEVAR furnace chamber;
a preheated silicon electrode drive system for lowering the preheated silicon electrode within the short CEVAR open-bottomed crucible as a lower end of the preheated silicon electrode melts in the CEVAR purification process;
an ingot heating apparatus disposed adjacent to the open bottom of the short CEVAR open-bottomed crucible through which the purified silicon ingot formed in the CEVAR purification process passes;
an ingot heating controller for controlling the ingot heating apparatus to provide a temperature-controlled thermal environment for the purified silicon ingot passing through the ingot heating apparatus; and
an ingot withdrawal drive system for alternatively withdrawing the purified silicon ingot from the short CEVAR open-bottomed crucible at a vertical growth rate of the purified silicon ingot during a steady state of the CEVAR purification process or raising the short CEVAR open-bottomed crucible, the silicon electrode and the ingot heating apparatus at the vertical growth rate of the purified silicon ingot during the steady state of the CEVAR purification process.
14. The CEVAR furnace system of claim 13 wherein an interior height of the short CEVAR opened-bottom crucible is at least 60 percent and less than 120 percent of a diameter of the purified silicon ingot formed in the CEVAR purification process.
15. The CEVAR furnace system of claim 13 further comprising a thermal insulation disposed around the preheated silicon electrode in the gas-tight CEVAR furnace chamber.
16. The CEVAR furnace system of claim 15 wherein the thermal insulation comprises a carbon fiber insulating material.
17. The CEVAR furnace system of claim 13, the base having a contour for interlocking contact with the bottom of the purified silicon ingot.
18. The CEVAR furnace system of claim 13, the short CEVAR opened-bottom crucible having an interior wall with a rectangular cross section, the interior height of the short CEVAR opened-bottom crucible being at least 60 percent and less than 120 percent of the length of a rectangular side of the purified silicon ingot formed in the CEVAR purification process.
19. The CEVAR furnace system of claim 13, the ingot withdrawal drive system further comprising a base upon which the bottom of the purified silicon ingot sits and a drive actuator connected to the base to control the rate of withdrawing of the purified silicon ingot from the short CEVAR open-bottomed crucible.
20. The CEVAR furnace system of claim 19 further comprising a DC power source having a first output and a second output connected respectively between the preheated silicon electrode and the base or the drive actuator.
US15/155,045 2011-08-26 2016-05-15 Purification of a metalloid by consumable electrode vacuum arc remelt process Abandoned US20160258684A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US15/155,045 US20160258684A1 (en) 2011-08-26 2016-05-15 Purification of a metalloid by consumable electrode vacuum arc remelt process

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US201161527799P 2011-08-26 2011-08-26
US13/586,149 US9340896B2 (en) 2011-08-26 2012-08-15 Purification of a metalloid by consumable electrode vacuum arc remelt process
US15/155,045 US20160258684A1 (en) 2011-08-26 2016-05-15 Purification of a metalloid by consumable electrode vacuum arc remelt process

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US13/586,149 Division US9340896B2 (en) 2011-08-26 2012-08-15 Purification of a metalloid by consumable electrode vacuum arc remelt process

Publications (1)

Publication Number Publication Date
US20160258684A1 true US20160258684A1 (en) 2016-09-08

Family

ID=47741677

Family Applications (2)

Application Number Title Priority Date Filing Date
US13/586,149 Expired - Fee Related US9340896B2 (en) 2011-08-26 2012-08-15 Purification of a metalloid by consumable electrode vacuum arc remelt process
US15/155,045 Abandoned US20160258684A1 (en) 2011-08-26 2016-05-15 Purification of a metalloid by consumable electrode vacuum arc remelt process

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US13/586,149 Expired - Fee Related US9340896B2 (en) 2011-08-26 2012-08-15 Purification of a metalloid by consumable electrode vacuum arc remelt process

Country Status (10)

Country Link
US (2) US9340896B2 (en)
EP (1) EP2748355B1 (en)
JP (1) JP5945601B2 (en)
KR (1) KR20140059823A (en)
CN (1) CN103764880B (en)
ES (1) ES2592814T3 (en)
HK (1) HK1197278A1 (en)
SG (1) SG2014013692A (en)
TW (1) TWI547451B (en)
WO (1) WO2013032703A2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112108086B (en) * 2020-09-24 2022-06-21 上海理工大学 Directional solidification segregation device and method for colloidal particle system

Citations (63)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3010009A (en) * 1958-09-29 1961-11-21 Plasmadyne Corp Method and apparatus for uniting materials in a controlled medium
US3033660A (en) * 1959-05-05 1962-05-08 Philips Corp Method and apparatus for drawing crystals from a melt
US3036549A (en) * 1957-05-08 1962-05-29 Sumitomo Electric Industries Apparatus for vacuum evaporation of metals
US3206302A (en) * 1961-05-29 1965-09-14 Finkl & Sons Co Method for degassing molten metal under high vacuum
US3344840A (en) * 1966-07-01 1967-10-03 Crucible Steel Co America Methods and apparatus for producing metal ingots
US3371140A (en) * 1964-11-09 1968-02-27 Mc Graw Edison Co Optical system for electric arc furnaces
US3387967A (en) * 1965-02-08 1968-06-11 Republic Steel Corp High purity steels and production thereof
US3389989A (en) * 1965-06-03 1968-06-25 Finkl & Sons Co Treatment of molten metal
US3491015A (en) * 1967-04-04 1970-01-20 Automatic Fire Control Inc Method of depositing elemental material from a low pressure electrical discharge
US3621213A (en) * 1969-11-26 1971-11-16 Ibm Programmed digital-computer-controlled system for automatic growth of semiconductor crystals
US3764297A (en) * 1971-08-18 1973-10-09 Airco Inc Method and apparatus for purifying metal
US3775091A (en) * 1969-02-27 1973-11-27 Interior Induction melting of metals in cold, self-lined crucibles
US3812899A (en) * 1973-03-28 1974-05-28 Latrobe Steel Co Controlled pressure consumable electrode vacuum arc remelting process
US3925177A (en) * 1973-01-30 1975-12-09 Boeing Co Method and apparatus for heating solid and liquid particulate material to vaporize or disassociate the material
US4096024A (en) * 1975-06-11 1978-06-20 Commissariat A L'energie Atomique Method for controlling the solidification of a liquid-solid system and a device for the application of the method
US4167554A (en) * 1974-10-16 1979-09-11 Metals Research Limited Crystallization apparatus having floating die member with tapered aperture
US4196171A (en) * 1977-09-05 1980-04-01 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for making a single crystal of III-V compound semiconductive material
US4267154A (en) * 1978-09-29 1981-05-12 Georg Mueller Apparatus for manufacturing high quality crystals
US4314128A (en) * 1980-01-28 1982-02-02 Photowatt International, Inc. Silicon growth technique and apparatus using controlled microwave heating
US4333962A (en) * 1979-09-04 1982-06-08 Balzers Aktiengesellschaft Method for producing gold color coatings
US4352189A (en) * 1977-03-01 1982-09-28 Wooding Corporation Atmosphere control of slag melting furnace
US4435818A (en) * 1981-05-26 1984-03-06 Leybold-Heraeus Gmbh Method and apparatus for monitoring the melting process in vacuum arc furnaces
US4497777A (en) * 1981-04-28 1985-02-05 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for producing monocrystalline silicon
US4505948A (en) * 1983-05-13 1985-03-19 Wedtech Corp. Method of coating ceramics and quartz crucibles with material electrically transformed into a vapor phase
US4510609A (en) * 1984-01-31 1985-04-09 The United States Of America As Represented By The Secretary Of The Army Furnace for vertical solidification of melt
US4556784A (en) * 1982-10-08 1985-12-03 Sumitomo Electric Industries, Ltd. Method for controlling vertically arranged heaters in a crystal pulling device
US4612649A (en) * 1983-11-10 1986-09-16 Cabot Corporation Process for refining metal
US4628174A (en) * 1984-09-17 1986-12-09 General Electric Company Forming electrical conductors in long microdiameter holes
US4637032A (en) * 1984-12-18 1987-01-13 Retech, Inc. Rotary seal for movable shaft to eliminate breakaway friction
US4832922A (en) * 1984-08-31 1989-05-23 Gakei Electric Works Co., Ltd. Single crystal growing method and apparatus
US4859489A (en) * 1988-07-18 1989-08-22 Vapor Technologies Inc. Method of coating a metal gas-pressure bottle or tank
US4898623A (en) * 1988-12-09 1990-02-06 Vapor Technologies Inc. Method of shaping hard difficult-to-roll alloys
US4918705A (en) * 1989-07-06 1990-04-17 General Electric Company Furnace enclosure having a clear viewpath
US5062936A (en) * 1989-07-12 1991-11-05 Thermo Electron Technologies Corporation Method and apparatus for manufacturing ultrafine particles
US5194128A (en) * 1989-07-12 1993-03-16 Thermo Electron Technologies Corporation Method for manufacturing ultrafine particles
US5240685A (en) * 1982-07-08 1993-08-31 Zaidan Hojin Handotai Kenkyu Shinkokai Apparatus for growing a GaAs single crystal by pulling from GaAs melt
US5373529A (en) * 1992-02-27 1994-12-13 Sandia Corporation Metals purification by improved vacuum arc remelting
US5476555A (en) * 1992-08-31 1995-12-19 Sps Technologies, Inc. Nickel-cobalt based alloys
US5496459A (en) * 1992-03-03 1996-03-05 El-Plasma Ltd. Apparatus for the treating of metal surfaces
US5621751A (en) * 1995-04-21 1997-04-15 Sandia Corporation Controlling electrode gap during vacuum arc remelting at low melting current
US5737355A (en) * 1995-09-21 1998-04-07 Sandia Corporation Directly induced swing for closed loop control of electroslag remelting furnace
US5830540A (en) * 1994-09-15 1998-11-03 Eltron Research, Inc. Method and apparatus for reactive plasma surfacing
US6001495A (en) * 1997-08-04 1999-12-14 Oregon Metallurgical Corporation High modulus, low-cost, weldable, castable titanium alloy and articles thereof
US6117230A (en) * 1996-12-17 2000-09-12 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Process for producing a silicon single crystal, and heater for carrying out the process
US6187089B1 (en) * 1999-02-05 2001-02-13 Memc Electronic Materials, Inc. Tungsten doped crucible and method for preparing same
US6295309B1 (en) * 2000-08-31 2001-09-25 General Electric Company Vacuum arc remelting apparatus and process
US6350293B1 (en) * 1999-02-23 2002-02-26 General Electric Company Bottom pour electroslag refining systems and methods
US6358323B1 (en) * 1998-07-21 2002-03-19 Applied Materials, Inc. Method and apparatus for improved control of process and purge material in a substrate processing system
US6395151B1 (en) * 2000-10-26 2002-05-28 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Vacuum ARC vapor deposition method and apparatus for applying identification symbols to substrates
US6398867B1 (en) * 1999-10-06 2002-06-04 General Electric Company Crystalline gallium nitride and method for forming crystalline gallium nitride
US6479108B2 (en) * 2000-11-15 2002-11-12 G.T. Equipment Technologies, Inc. Protective layer for quartz crucibles used for silicon crystallization
US6605152B2 (en) * 2000-03-03 2003-08-12 Shin-Etsu Handotai Co., Ltd. Catch pan for melt leakage in apparatus for pulling single crystal
US6614832B1 (en) * 1999-05-31 2003-09-02 Stahlwerk Thueringen Gmbh Method of determining electrode length and bath level in an electric arc furnace
US6749685B2 (en) * 2001-08-16 2004-06-15 Cree, Inc. Silicon carbide sublimation systems and associated methods
US20040218657A1 (en) * 2003-03-01 2004-11-04 Ivaylov Popov Method and device for equalizing the pressures in the melting chamber and the cooling water system of a special melting unit
US6866752B2 (en) * 2001-08-23 2005-03-15 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method of forming ultra thin film devices by vacuum arc vapor deposition
US20050223849A1 (en) * 2002-12-23 2005-10-13 General Electric Company Method for making and using a rod assembly
US20070195852A1 (en) * 2005-08-18 2007-08-23 Bp Corporation North America Inc. Insulation Package for Use in High Temperature Furnaces
US20080298425A1 (en) * 2007-06-01 2008-12-04 Tinomics, Llc Method and apparatus for melting metals using both alternating current and direct current
US20100050932A1 (en) * 2008-08-27 2010-03-04 Bp Corporation North America Inc. Apparatus and Method of Direct Electric Melting a Feedstock
US7959732B1 (en) * 2005-06-17 2011-06-14 Saint-Gobain Ceramics & Plastics, Inc. Apparatus and method for monitoring and controlling crystal growth
US8381385B2 (en) * 2004-12-27 2013-02-26 Tri-Arrows Aluminum Inc. Shaped direct chill aluminum ingot
US20130164167A1 (en) * 2011-12-22 2013-06-27 Universal Technical Resource Services, Inc. System and method for extraction and refining of titanium

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3008887A (en) * 1958-10-08 1961-11-14 Du Pont Purification process
US3187079A (en) 1962-11-08 1965-06-01 Crucible Steel Co America Electrode clamp
US3480716A (en) 1967-12-11 1969-11-25 United Aircraft Corp Multiple electrode vacuum arc furnace and method of remelt purification
US3546348A (en) 1968-04-01 1970-12-08 Westinghouse Electric Corp Non-consumable electrode vacuum arc furnaces for steel,zirconium,titanium and other metals and processes for working said metals
US4303797A (en) 1980-06-20 1981-12-01 Consarc Corporation Method and apparatus for controlling electrode drive speed in a consumable electrode furnace
EP0150543A1 (en) 1984-01-20 1985-08-07 Westinghouse Electric Corporation Method and apparatus for arc welding
US4569056A (en) 1984-04-27 1986-02-04 Carpenter Technology Corporation Consumable electrode remelting furnace and method
JPH0820827A (en) * 1994-07-07 1996-01-23 Hitachi Ltd Electro-slag remelting method
JPH0835019A (en) * 1994-07-21 1996-02-06 Hitachi Ltd Electro-slag remelting method
JP4214118B2 (en) 2005-02-04 2009-01-28 株式会社大阪チタニウムテクノロジーズ Consumable electrode manufacturing method for consumable electrode arc melting method and end face cutting device used therefor
LV13528B (en) * 2006-09-25 2007-03-20 Ervins Blumbergs Method and apparatus for continuous producing of metallic tifanium and titanium-bases alloys
WO2009018425A1 (en) 2007-08-01 2009-02-05 Boston Silicon Materials Llc Process for the production of high purity elemental silicon
CN101935040A (en) * 2009-06-29 2011-01-05 上海奇谋能源技术开发有限公司 Method for removing low-temperature impurities from silicon by vacuum electric arc melting method
CN201608933U (en) * 2009-12-11 2010-10-13 北京有色金属研究总院 Electrode used for vacuum consumable electric arc melting
WO2011099110A1 (en) 2010-02-09 2011-08-18 Kaneko Kyojiro Silicon vacuum melting method
CN201593917U (en) * 2010-02-23 2010-09-29 杭州大华仪器制造有限公司 Self-casting vacuum arc melting furnace

Patent Citations (63)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3036549A (en) * 1957-05-08 1962-05-29 Sumitomo Electric Industries Apparatus for vacuum evaporation of metals
US3010009A (en) * 1958-09-29 1961-11-21 Plasmadyne Corp Method and apparatus for uniting materials in a controlled medium
US3033660A (en) * 1959-05-05 1962-05-08 Philips Corp Method and apparatus for drawing crystals from a melt
US3206302A (en) * 1961-05-29 1965-09-14 Finkl & Sons Co Method for degassing molten metal under high vacuum
US3371140A (en) * 1964-11-09 1968-02-27 Mc Graw Edison Co Optical system for electric arc furnaces
US3387967A (en) * 1965-02-08 1968-06-11 Republic Steel Corp High purity steels and production thereof
US3389989A (en) * 1965-06-03 1968-06-25 Finkl & Sons Co Treatment of molten metal
US3344840A (en) * 1966-07-01 1967-10-03 Crucible Steel Co America Methods and apparatus for producing metal ingots
US3491015A (en) * 1967-04-04 1970-01-20 Automatic Fire Control Inc Method of depositing elemental material from a low pressure electrical discharge
US3775091A (en) * 1969-02-27 1973-11-27 Interior Induction melting of metals in cold, self-lined crucibles
US3621213A (en) * 1969-11-26 1971-11-16 Ibm Programmed digital-computer-controlled system for automatic growth of semiconductor crystals
US3764297A (en) * 1971-08-18 1973-10-09 Airco Inc Method and apparatus for purifying metal
US3925177A (en) * 1973-01-30 1975-12-09 Boeing Co Method and apparatus for heating solid and liquid particulate material to vaporize or disassociate the material
US3812899A (en) * 1973-03-28 1974-05-28 Latrobe Steel Co Controlled pressure consumable electrode vacuum arc remelting process
US4167554A (en) * 1974-10-16 1979-09-11 Metals Research Limited Crystallization apparatus having floating die member with tapered aperture
US4096024A (en) * 1975-06-11 1978-06-20 Commissariat A L'energie Atomique Method for controlling the solidification of a liquid-solid system and a device for the application of the method
US4352189A (en) * 1977-03-01 1982-09-28 Wooding Corporation Atmosphere control of slag melting furnace
US4196171A (en) * 1977-09-05 1980-04-01 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for making a single crystal of III-V compound semiconductive material
US4267154A (en) * 1978-09-29 1981-05-12 Georg Mueller Apparatus for manufacturing high quality crystals
US4333962A (en) * 1979-09-04 1982-06-08 Balzers Aktiengesellschaft Method for producing gold color coatings
US4314128A (en) * 1980-01-28 1982-02-02 Photowatt International, Inc. Silicon growth technique and apparatus using controlled microwave heating
US4497777A (en) * 1981-04-28 1985-02-05 Tokyo Shibaura Denki Kabushiki Kaisha Apparatus for producing monocrystalline silicon
US4435818A (en) * 1981-05-26 1984-03-06 Leybold-Heraeus Gmbh Method and apparatus for monitoring the melting process in vacuum arc furnaces
US5240685A (en) * 1982-07-08 1993-08-31 Zaidan Hojin Handotai Kenkyu Shinkokai Apparatus for growing a GaAs single crystal by pulling from GaAs melt
US4556784A (en) * 1982-10-08 1985-12-03 Sumitomo Electric Industries, Ltd. Method for controlling vertically arranged heaters in a crystal pulling device
US4505948A (en) * 1983-05-13 1985-03-19 Wedtech Corp. Method of coating ceramics and quartz crucibles with material electrically transformed into a vapor phase
US4612649A (en) * 1983-11-10 1986-09-16 Cabot Corporation Process for refining metal
US4510609A (en) * 1984-01-31 1985-04-09 The United States Of America As Represented By The Secretary Of The Army Furnace for vertical solidification of melt
US4832922A (en) * 1984-08-31 1989-05-23 Gakei Electric Works Co., Ltd. Single crystal growing method and apparatus
US4628174A (en) * 1984-09-17 1986-12-09 General Electric Company Forming electrical conductors in long microdiameter holes
US4637032A (en) * 1984-12-18 1987-01-13 Retech, Inc. Rotary seal for movable shaft to eliminate breakaway friction
US4859489A (en) * 1988-07-18 1989-08-22 Vapor Technologies Inc. Method of coating a metal gas-pressure bottle or tank
US4898623A (en) * 1988-12-09 1990-02-06 Vapor Technologies Inc. Method of shaping hard difficult-to-roll alloys
US4918705A (en) * 1989-07-06 1990-04-17 General Electric Company Furnace enclosure having a clear viewpath
US5062936A (en) * 1989-07-12 1991-11-05 Thermo Electron Technologies Corporation Method and apparatus for manufacturing ultrafine particles
US5194128A (en) * 1989-07-12 1993-03-16 Thermo Electron Technologies Corporation Method for manufacturing ultrafine particles
US5373529A (en) * 1992-02-27 1994-12-13 Sandia Corporation Metals purification by improved vacuum arc remelting
US5496459A (en) * 1992-03-03 1996-03-05 El-Plasma Ltd. Apparatus for the treating of metal surfaces
US5476555A (en) * 1992-08-31 1995-12-19 Sps Technologies, Inc. Nickel-cobalt based alloys
US5830540A (en) * 1994-09-15 1998-11-03 Eltron Research, Inc. Method and apparatus for reactive plasma surfacing
US5621751A (en) * 1995-04-21 1997-04-15 Sandia Corporation Controlling electrode gap during vacuum arc remelting at low melting current
US5737355A (en) * 1995-09-21 1998-04-07 Sandia Corporation Directly induced swing for closed loop control of electroslag remelting furnace
US6117230A (en) * 1996-12-17 2000-09-12 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Process for producing a silicon single crystal, and heater for carrying out the process
US6001495A (en) * 1997-08-04 1999-12-14 Oregon Metallurgical Corporation High modulus, low-cost, weldable, castable titanium alloy and articles thereof
US6358323B1 (en) * 1998-07-21 2002-03-19 Applied Materials, Inc. Method and apparatus for improved control of process and purge material in a substrate processing system
US6187089B1 (en) * 1999-02-05 2001-02-13 Memc Electronic Materials, Inc. Tungsten doped crucible and method for preparing same
US6350293B1 (en) * 1999-02-23 2002-02-26 General Electric Company Bottom pour electroslag refining systems and methods
US6614832B1 (en) * 1999-05-31 2003-09-02 Stahlwerk Thueringen Gmbh Method of determining electrode length and bath level in an electric arc furnace
US6398867B1 (en) * 1999-10-06 2002-06-04 General Electric Company Crystalline gallium nitride and method for forming crystalline gallium nitride
US6605152B2 (en) * 2000-03-03 2003-08-12 Shin-Etsu Handotai Co., Ltd. Catch pan for melt leakage in apparatus for pulling single crystal
US6295309B1 (en) * 2000-08-31 2001-09-25 General Electric Company Vacuum arc remelting apparatus and process
US6395151B1 (en) * 2000-10-26 2002-05-28 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Vacuum ARC vapor deposition method and apparatus for applying identification symbols to substrates
US6479108B2 (en) * 2000-11-15 2002-11-12 G.T. Equipment Technologies, Inc. Protective layer for quartz crucibles used for silicon crystallization
US6749685B2 (en) * 2001-08-16 2004-06-15 Cree, Inc. Silicon carbide sublimation systems and associated methods
US6866752B2 (en) * 2001-08-23 2005-03-15 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method of forming ultra thin film devices by vacuum arc vapor deposition
US20050223849A1 (en) * 2002-12-23 2005-10-13 General Electric Company Method for making and using a rod assembly
US20040218657A1 (en) * 2003-03-01 2004-11-04 Ivaylov Popov Method and device for equalizing the pressures in the melting chamber and the cooling water system of a special melting unit
US8381385B2 (en) * 2004-12-27 2013-02-26 Tri-Arrows Aluminum Inc. Shaped direct chill aluminum ingot
US7959732B1 (en) * 2005-06-17 2011-06-14 Saint-Gobain Ceramics & Plastics, Inc. Apparatus and method for monitoring and controlling crystal growth
US20070195852A1 (en) * 2005-08-18 2007-08-23 Bp Corporation North America Inc. Insulation Package for Use in High Temperature Furnaces
US20080298425A1 (en) * 2007-06-01 2008-12-04 Tinomics, Llc Method and apparatus for melting metals using both alternating current and direct current
US20100050932A1 (en) * 2008-08-27 2010-03-04 Bp Corporation North America Inc. Apparatus and Method of Direct Electric Melting a Feedstock
US20130164167A1 (en) * 2011-12-22 2013-06-27 Universal Technical Resource Services, Inc. System and method for extraction and refining of titanium

Also Published As

Publication number Publication date
SG2014013692A (en) 2014-05-29
WO2013032703A3 (en) 2013-05-10
EP2748355B1 (en) 2016-08-10
EP2748355A4 (en) 2015-05-20
CN103764880B (en) 2016-10-26
TWI547451B (en) 2016-09-01
KR20140059823A (en) 2014-05-16
CN103764880A (en) 2014-04-30
JP5945601B2 (en) 2016-07-05
US9340896B2 (en) 2016-05-17
EP2748355A2 (en) 2014-07-02
HK1197278A1 (en) 2015-01-09
TW201313631A (en) 2013-04-01
JP2014529568A (en) 2014-11-13
ES2592814T3 (en) 2016-12-01
WO2013032703A2 (en) 2013-03-07
US20130047670A1 (en) 2013-02-28

Similar Documents

Publication Publication Date Title
US5510095A (en) Production of high-purity silicon ingot
US6695035B2 (en) Electromagnetic induction casting apparatus
US7381366B2 (en) Apparatus for the production or refining of metals, and related processes
US4915723A (en) Apparatus for casting silicon with gradual cooling
US20060037733A1 (en) Electromagnetic continuous casting apparatus for materials possessing high melting temperature and low electric conductance
JP2007051026A (en) Method for casting silicon polycrystal
JPH0258022B2 (en)
US20070006916A1 (en) Solar-cell polycrystalline silicon and method for producing the same
JP3646570B2 (en) Silicon continuous casting method
KR101574247B1 (en) Continuous casting equipment and method for high purity silicon
US20160258684A1 (en) Purification of a metalloid by consumable electrode vacuum arc remelt process
JP2657240B2 (en) Silicon casting equipment
JP3603676B2 (en) Silicon continuous casting method
RU2403299C1 (en) Vacuum silicone cleaning method and device for its implementation (versions)
JP2012512126A (en) Process for producing polycrystalline silicon ingot by induction method and equipment for carrying out the process
KR20120101046A (en) Electromagnetic casting apparatus for silicon
KR100981134B1 (en) A high-purity silicon ingot with solar cell grade, a system and method for manufacturing the same by refining a low-purity scrap silicon
KR101323191B1 (en) Manufacturing method of silicon for solar cell using metallurgical process
WO2011099208A1 (en) Silicon vacuum melting method
JP2005059015A (en) Device for melting and casting metal
KR20120031421A (en) Electromagnetic casting method for silicon ingot
KR101854257B1 (en) Silicon refining apparatus for solar cell and its method
RU2403300C1 (en) Vacuum silicone cleaning method and device for its implementation
KR20120126913A (en) Electromagnetic continuous casting machine for producing silicon ingot
JP2004042106A (en) Rapid-casting apparatus

Legal Events

Date Code Title Description
AS Assignment

Owner name: CONSARC CORPORATION, NEW JERSEY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ROBERTS, RAYMOND J.;REEL/FRAME:038723/0133

Effective date: 20121024

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION