US3340017A - Method of crucible-free zone melting - Google Patents

Method of crucible-free zone melting Download PDF

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Publication number
US3340017A
US3340017A US447663A US44766365A US3340017A US 3340017 A US3340017 A US 3340017A US 447663 A US447663 A US 447663A US 44766365 A US44766365 A US 44766365A US 3340017 A US3340017 A US 3340017A
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US
United States
Prior art keywords
rod
ring
zone
flux
heater coil
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.)
Expired - Lifetime
Application number
US447663A
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English (en)
Inventor
Keller Wolfgang
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.)
Siemens Schuckertwerke AG
Siemens Corp
Original Assignee
Siemens 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 Siemens Corp filed Critical Siemens Corp
Application granted granted Critical
Publication of US3340017A publication Critical patent/US3340017A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • 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
    • C30B13/16—Heating of the molten zone
    • C30B13/20—Heating of the molten zone by induction, e.g. hot wire technique
    • 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
    • Y10S117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10S117/901—Levitation, reduced gravity, microgravity, space
    • 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
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1024—Apparatus for crystallization from liquid or supercritical state
    • Y10T117/1076—Apparatus for crystallization from liquid or supercritical state having means for producing a moving solid-liquid-solid zone
    • Y10T117/1084—Apparatus for crystallization from liquid or supercritical state having means for producing a moving solid-liquid-solid zone having details of a stabilizing feature
    • 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
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1024—Apparatus for crystallization from liquid or supercritical state
    • Y10T117/1076—Apparatus for crystallization from liquid or supercritical state having means for producing a moving solid-liquid-solid zone
    • Y10T117/1088—Apparatus for crystallization from liquid or supercritical state having means for producing a moving solid-liquid-solid zone including heating or cooling details

Definitions

  • My invention relates to a method of crucible-free zone melting of a rod-shaped, crystalline member held by its ends in a vertical position.
  • crucible-free zone melting Various methods of crucible-free zone melting are known.
  • a crystalline rod is held at its ends in a vertical position within an evacuated vessel or one filled with a protective gas.
  • a heating device surrounding the rod serves for melting a short length thereof, the so-called melting zone.
  • the melting zone is passed over the entire length of the rod.
  • An induction heating coil has been found to be a particularly suitable heating device since, by means of such coil, the melting zone can be supplied with the necessary power for melting the rod without danger of contamination due to contact or the like.
  • German Patent No. 1,094,710 or Canadian Patent No. 642,713 it is further known from German Patent No. 1,094,710 or Canadian Patent No. 642,713, for example, to attach to one end of a semiconductor rod, in a crucible-free zone melting process, a seed crystal whose cross section is much smaller than that of the treated rod. In this way, the quality of the resulting monocrystal is improved, especially with respect to the density of the dislocations.
  • I provide a method of crucible-free zone melting of a rod-shaped member vertically held at its ends, the member being of crystalllne semiconductor material, particularly silicon, and having a rod diameter exceeding 30 mm.
  • An induction heating coil which surrounds the rod and is energized with high frequency alternating current, is movable along the rod axis.
  • a short-circuiting ring of good electric conductance material which compensates a portion of the heating coil field, is located below the coil, and, attached to the lower end of the rod-shaped body, is a crystal seed whose cross section is considerably smaller than the cross section of the rod-shaped body.
  • the melting zone produced with the aid of the induction heating coil is passed upwardly several times through the body, starting from the seed crystal. Thereby, at least the first pass of the melting zone is carried out with an effective partial compensation of the heating coil field, and thereafter at least one additional pass of the melting zone is performed without any partial compensation of the heating coil field.
  • a semiconductor rod to be processed is inserted into a zone melting device wherein a shortcircuiting ring is located below the heating coil.
  • a narrow seed crystal is inserted from below so that it extends up to the semiconductor rod.
  • the seed crystal is stood up in the lower holder, while the semiconductor rod is hung from the upper holder. If the semiconductor rod is then melted at its lower end, for example by energizing the heating coil after first preheating the rod until it is capable of absorbing a current, a partial compensation of the heating coil field occurs due to the presence of the short-circuiting ring. The result is that the heating coil is effective only at its upper end.
  • the junction between the seed crystal and the treated rod has an outwardly curved shape, so that during further melting, no tearing or dripping off of the melting zone need be feared.
  • the remaining portion of the semiconductor rod is made uniform in cross section and thickness, and especially when the semiconductor rod is rotated during zone melting, it is of circular, well centered shape.
  • the short-circuiting ring can then either be removed or the semiconductor rod may be withdrawn from the zone melting device and transferred to another zone melting device without a short-circuiting ring.
  • the semiconductor rod frequently has dislocations in the monocrystalline growth so that subsequent treatment, Without the short-circuiting ring, is necessary.
  • the melting zone may be passed one or more times through the semiconductor rod. It has been found that a smaller number of passes of the melting zone, for example two or three, are required to transform the semiconductor rod into a monocrystal after removal of the short-circuiting ring.
  • FIG. 2 is a fragmentary view of a semiconductor rod with a smooth end and a seed crystal in alignment prior to being joined together;
  • FIG. 4 shows a modified short-circuiting ring employed in carrying out my inventive method which is opened by opening a pair of switch contacts.
  • the partial compensation of the heating coil field can be eliminated without removing the ring 15 from the apparatus by opening the contacts, since no current can consequently flow in the thus open ring 15, so that there is then no compensation of the heating coil field in this region.
  • the ring comprises a flexible tube in the form of a loop having engageable contacts respectively on the end portions thereof, the tubular ring being traversible by fluid coolant, and being opened so as to disengage the contacts by varying the pressure of the fluid coolant in the tube.
  • a method of zone melting a polycrystalline rod having a diameter greater than 30 mm. so as to form a monocrystal thereof wherein the rod and a seed crystal of relatively small diameter are supported at the upper and lower end thereof respectively in vertical alignment with each other the rod overlying the seed crystal in a first zone melting apparatus and a molten zone is formed in the rod at a junction of the rod, and the seed crystal by a surrounding inductive heater coil energized by current from a high-frequency generator having a flux field, the molten zone being prevented from dripping by a short circuiting ring of electrically conducting material surrounding the rod and located beneath the heater coil at a distance therefrom adapted to induce in the ring a counter current with a flux opposing the flux of the heater coil in the region encompassed by the ring for compensating at least part of the heater coil flux so;
  • the improvement which comprises relatively moving the rod on the one hand and the heater coil and the ring on the other hand in the direction of the rod axis so as to pass the molten zone at least once upwardly along the rod from the junction and thereby simultaneously partly com pensating the heater ICOll flux with the ring to support the upwardly passing molten zone, then removing the joined rod and seed crystal and supporting the same vertically at the ends thereof in a second zone melting apparatus, forming a molten zone in the rod at the junction of the rod and the seed crystal by a surrounding inductive heater coil of the second apparatus energized by current from a high-frequency generator, and relatively moving the rod and the heater coil in the direction of the rod axis so as to pass the molten zone at least once upwardly along the rod from the junction with the short circuiting ring removed without compensating the heater coil flux.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
  • Silicon Compounds (AREA)
US447663A 1964-04-15 1965-04-13 Method of crucible-free zone melting Expired - Lifetime US3340017A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES90543A DE1245319B (de) 1964-04-15 1964-04-15 Verfahren zum tiegelfreien Zonenschmelzen

Publications (1)

Publication Number Publication Date
US3340017A true US3340017A (en) 1967-09-05

Family

ID=7515902

Family Applications (1)

Application Number Title Priority Date Filing Date
US447663A Expired - Lifetime US3340017A (en) 1964-04-15 1965-04-13 Method of crucible-free zone melting

Country Status (6)

Country Link
US (1) US3340017A (de)
BE (1) BE662546A (de)
CH (1) CH418311A (de)
DE (1) DE1245319B (de)
GB (1) GB1041504A (de)
NL (1) NL6502374A (de)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1164681B (de) * 1958-12-24 1964-03-05 Siemens Ag Verfahren zur Herstellung eines gleichmaessig dotierten Stabes aus Halbleitermaterial durch tiegelfreies Zonenschmelzen
DE1115714B (de) * 1959-09-23 1961-10-26 Siemens Ag Verfahren zur Herstellung von einkristallinem Halbleitermaterial
NL253526A (de) * 1959-08-14

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
DE1245319B (de) 1967-07-27
BE662546A (de) 1965-10-15
CH418311A (de) 1966-08-15
NL6502374A (de) 1965-10-18
GB1041504A (en) 1966-09-07

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