US3391235A - Apparatus for crucible-free zone melting with a vacuum chamber - Google Patents

Apparatus for crucible-free zone melting with a vacuum chamber Download PDF

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Publication number
US3391235A
US3391235A US501674A US50167465A US3391235A US 3391235 A US3391235 A US 3391235A US 501674 A US501674 A US 501674A US 50167465 A US50167465 A US 50167465A US 3391235 A US3391235 A US 3391235A
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US
United States
Prior art keywords
chamber
slot
plate
rod
vacuum chamber
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Expired - Lifetime
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US501674A
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English (en)
Inventor
Emeis Reimer
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Siemens AG
Siemens Corp
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Siemens Corp
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Filing date
Publication date
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    • 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
    • C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
    • C30B13/32—Mechanisms for moving either the charge or the heater
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/22—Furnaces without an endless core
    • H05B6/30—Arrangements for remelting or zone melting
    • 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S65/00—Glass manufacturing
    • Y10S65/04—Electric heat

Definitions

  • Apparatus for crucible-free zone melting with a vacuum chamber having holders by means of which the rodshaped material to be processed is held in a vertical posi tion and further having heating means located in the vacuum chamber and actuable from outside the chamber so as to be displaceable vertically upward and downward, have heretofore become known.
  • a melting zone is produced in the rod-shaped material and is passed by relative motion between the rod-shaped material and the heating device over the entire length of the rod-shaped material.
  • the heating device or the rod can be displaceable in a vertical direction.
  • the rod holders are preferably rotatable about the vertical axis so as to achieve a uniform cross section.
  • the size of the rod cross section can be kept uniform by moving the rod holders toward and away from one another in response to optical or electrical measurement values, for example, whereby the melting zone is respectively thickened or stretched, i.e. compressed or elongated respectively, so that the material crysallizing out of the melting zone has a respective enlarged or reduced cross section.
  • the solution provided by the apparatus of the aforementioned patent has the advantage that the holder of the heating device, the current leads to the heating device, and, if necessary, a coolant loop for the heating device, can be combined together so that only one apertured fitting in the wall of the vacuum vessel is necessary for this operating equipment.
  • the induction heating coil is connected in parallel with a capacitance comprising a bank of condensers forming a resonant heating circuit with the induction heating coil that is energized by a high frequency generator. If the spacing between the capacitance and the inductance of this heating circuit is relatively large, which can be the case for semiconductor rod material being processed having a very great length, the losses in the heating circuit will then be disproportionately large.
  • I provide in accordance with my invention apparatus for cruciblefree zone melting comprising a vacuum chamber, holders mounted in the chamber for holding the rod-shaped material to be processed in a vertical position, and a heating device mounted so as to be displaceable in the vacuum chamber in a vertical direction and movable from outside the vacuum chamber.
  • a vertically extending slot is formed in a side wall of the vacuum chamber and is covered by a plate which is displaceable in a vertical direction and a holder for the heating device extending through the slot and secured to the plate.
  • the spacing between the current leads to the electrical heating device, that are located outside the vacuum chamber, and the heating device proper is consequently always relatively small and independent of the rod length of the material that is being processed.
  • the mechanical stability of the holder of the heating device is thereby also promoted.
  • FIG. 1 is a vertical sectional view of a zone melting apparatus constructed in accordance with my invention
  • FIG. 2 is a cross sectional view of FIG. 1 taken along the line II--II in the direction of the arrows;
  • FIG. 3 is a right-hand side view of FIG. 1 with the outer plate and heating coil holder removed, showing details of the seal for the slot formed in the side wall of the vacuum vessel.
  • a zone melting apparatus having a box-shaped housing 2 which can consist, for example, of steel.
  • a door 3 is located in a side wall of the vacuum chamber which will accordingly be referred to herein as the front wall of the zone melting apparatus.
  • a window 4 which can, for example, consist of bullet-proof glass.
  • the material to be processed is in the form of a rod 5 located within the vacuum vessel, and can, for example, consist of a semiconductor rod of silicon.
  • the rod 5 is held between two holders 6 and 7 which can be moved with the aid of the shafts 8 and 8' from outside the vacuum vessel.
  • the holder 7 can be rotated about its axis as indicated by the curved arrow associated therewith whereas the other holder 6 can be moved up and back vertically, as indicated by the double-headed arrow associated therewith, and can accordingly perform the aforedescribed stretching and compressing motion for equalizing or varying the cross section of the material being processed.
  • both holders 6 and 7 can be simultaneously rotated and/ or displaced in a vertical direction, as viewed in FIG. 1.
  • an electrical heating device 9 for example an induction heating coil
  • a melting zone 10 can be produced in the rod 5. This heating can also be accomplished by any suitable radiation heating device.
  • a connecting conduit 11 by the aid of which the interior of the vacuum chamber 2 can be evacuated.
  • a vertical slot 12 In another side wall, referred to hereinafter as the rear wall and located at the right-hand side of FIG. 1 and opposite to the front wall containing the viewing window 4 through which supervising personnel can see the rear wall, there is formed a vertical slot 12.
  • the slot 12 is covered by a plate 13 serving to seal off the slot from the surrounding air.
  • a holder 14 for the heating device 9 is secured to this plate 13.
  • the holder 14 preferably extends vacuum-tightly through the plate 13 so that it can serve simultaneously as the conductive supply line for the current and, if necessary, as means for supplying coolant such as cool water through a cooling loop therein.
  • coolant such as cool water
  • the holder 14 extends with clearance through the slot 12 permitting the holder 14 and therewith also the heating device 9 to be displaced with the plate 13 in a vertical direction.
  • the plate 13 is made longer than the slot 12 so that the slot always remains covered when the plate 13 is moved vertically.
  • the plate 13 are accommodated to one another, for example by grinding and polishing so that an effective sealing of the slot 12 is assured.
  • An intermediate member can also be provided which can be sealingly placed on the exterior of the vacuum chamber 2 surrounding the slot 12, and the plate 13 can be located thereon for displacement in a vertical direction. The production and machining of the sliding surfaces for the plate 13 are thereby greatly facilitated.
  • a groove 15 is additionally provided in the rear wall completely surrounding the slot 12 and filled with a sealing liquid such as oil for example.
  • a sealing liquid such as oil for example.
  • vacuu-m oil which has a very low vapor pressure
  • the inner space of the vacuum chamber can be safely sealed from the outer air.
  • An equalizing vessel 16 is preferably provided for replacing the oil loss in the groove 15 and serves simultaneously for equalizing heat expansion of the sealing liquid.
  • a collecting groove or vessel 17 for receiving the liquid sealant which may run or flow down the plate 13.
  • the oil in the groove 15 is under outer atmospheric pressure (1 at), so that in a disadvantageous case some of the oil will reach into the vacuum vessel.
  • a further improvement can accordingly be effected by providing a second groove 18 in the rear wall which also completely surrounds the slot 12 and which is located between the slot and the groove 15 that is filled with sealant liquid.
  • a vacuum pump with a pre-vacuum is necessary to produce a high vacuum in the chamber of the apparatus; in this case the groove 18 can be connected to the pre-vacuum so that, if necessary, sealant liquid originating from the groove 15 can be drained into the pre-vacuum before reaching the slot 12. The difiicult problem of the sealing can thus be solved.
  • FIG. 3 the rear wall of the vacuum chamber is shown with the plate 13 removed; the separate grooves 15 and 18 surrounding the slot 12 are clearly illustrated therein.
  • the capacitors (not shown) connected in parallel to the induction heating coil 9 are mounted in a housing 19 which is secured directly to the plate 13 at a location thereof through which the holder 14 extends.
  • the capacitors are water-cooled (from 2000 to 3000 pf. at 2 kv. and 4 mHz. frequency) it is very difii-cult to locate these capacitors inside the vacuum chamber 2, so that the inventive solution of this application avoids this dirliculty. As can be seen from FIGS.
  • the spacing between the induction heating coil 9 and the capacitor group or bank 19 is relatively small so that the losses from the holder 14 which acts as current conducting lead can also be kept very small whereas the inductance of the current connecting lead between the heating coil 9 and capacitance 19 for a different arrangement and thereby for a necessarily greater spacing in spite of the coaxial arrangement can have the order of magnitude of the inductance of the heating coil 9.
  • the electrical leads from a high-frequency generator and the coolant loop conduits can be readily inserted from the outside of the vacuum vessel, as clearly evident from the drawing and the disclosure herein.
  • Apparatus for crucible-free zone melting rod-shaped material comprising a vacuum chamber having a side wall, holding means mounted in said chamber for holding the rod-shaped material in a substantially vertical position, heating means located in said chamber for heating the rod-shaped material to form a melting zone therein, the side wall of said chamber being formed with a substantially vertically extending slot, a plate adjacent said side wall outside of said chamber for covering and her metically sealing said slot, said plate being displaceable from outside said chamber in a substantially vertical direction, and holder means for said heating means extending from said chamber through said slot and secured to said plate whereby said heating means may be vertically displaced with said plate for passing the molten zone vertically through the rod-shaped material.
  • Apparatus according to claim 2 including a supply vessel for sealing fluid located above and communicating with said groove.
  • Apparatus according to claim 2 including a second groove formed in said side wall and completely surrounding said slot, said second groove being located between said slot and said first-mentioned groove.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Furnace Details (AREA)
US501674A 1965-04-28 1965-10-22 Apparatus for crucible-free zone melting with a vacuum chamber Expired - Lifetime US3391235A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES96806A DE1262226B (de) 1965-04-28 1965-04-28 Vorrichtung zum tiegelfreien Zonenschmelzen mit einer Vakuumkammer

Publications (1)

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US3391235A true US3391235A (en) 1968-07-02

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US501674A Expired - Lifetime US3391235A (en) 1965-04-28 1965-10-22 Apparatus for crucible-free zone melting with a vacuum chamber

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US (1) US3391235A (enrdf_load_stackoverflow)
BE (1) BE680141A (enrdf_load_stackoverflow)
DE (1) DE1262226B (enrdf_load_stackoverflow)
GB (1) GB1083248A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3615245A (en) * 1966-09-24 1971-10-26 Siemens Ag Apparauts for rod displacement crucible-free zone melting
US3630684A (en) * 1966-09-24 1971-12-28 Siemens Ag Device for heater movement in crucible-free zone melting a crystalline rod
US3650700A (en) * 1968-01-16 1972-03-21 Siemens Ag Device for crucible-free zone melting having sealing means for a sliding member
US3833342A (en) * 1971-04-21 1974-09-03 Nat Res Dev Apparatus for the preparation and growth of crystalline material
US4092124A (en) * 1975-07-29 1978-05-30 Siemens Aktiengesellschaft Apparatus for floating melt zone processing of a semiconductor rod

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2937216A (en) * 1957-12-30 1960-05-17 Minnesota Mining & Mfg Zone refining apparatus
US3270177A (en) * 1960-01-20 1966-08-30 Merck & Co Inc Means and method for automatic zone refining a work piece

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2937216A (en) * 1957-12-30 1960-05-17 Minnesota Mining & Mfg Zone refining apparatus
US3270177A (en) * 1960-01-20 1966-08-30 Merck & Co Inc Means and method for automatic zone refining a work piece

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3615245A (en) * 1966-09-24 1971-10-26 Siemens Ag Apparauts for rod displacement crucible-free zone melting
US3630684A (en) * 1966-09-24 1971-12-28 Siemens Ag Device for heater movement in crucible-free zone melting a crystalline rod
US3650700A (en) * 1968-01-16 1972-03-21 Siemens Ag Device for crucible-free zone melting having sealing means for a sliding member
US3833342A (en) * 1971-04-21 1974-09-03 Nat Res Dev Apparatus for the preparation and growth of crystalline material
US4092124A (en) * 1975-07-29 1978-05-30 Siemens Aktiengesellschaft Apparatus for floating melt zone processing of a semiconductor rod

Also Published As

Publication number Publication date
BE680141A (enrdf_load_stackoverflow) 1966-10-27
GB1083248A (en) 1967-09-13
DE1262226B (de) 1968-03-07

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