US3561931A - Eccentric feed rotation in zone refining - Google Patents

Eccentric feed rotation in zone refining Download PDF

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Publication number
US3561931A
US3561931A US658512A US3561931DA US3561931A US 3561931 A US3561931 A US 3561931A US 658512 A US658512 A US 658512A US 3561931D A US3561931D A US 3561931DA US 3561931 A US3561931 A US 3561931A
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US
United States
Prior art keywords
rod
recrystallized
rod portion
heating device
supply
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
US658512A
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English (en)
Inventor
Carl-Heinz Vogel
Ludwig Sporrer
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Siemens AG
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Siemens AG
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Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
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Publication of US3561931A publication Critical patent/US3561931A/en
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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
    • 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
    • Y10S117/91—Downward pulling
    • 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
    • Y10S117/912—Replenishing liquid precursor, other than a moving zone
    • 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
    • Y10T117/1032—Seed pulling
    • Y10T117/1072—Seed pulling including details of means providing product movement [e.g., shaft guides, servo means]
    • 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

Definitions

  • Apparatus for carrying out the foregoing method includes substantially vertically spaced end holders supporting between them a vertically extending semiconductor rod having a recrystallized portion and a supply portion to be recrystallized divided by a molten zone, means for relatively displacing the end holders toward one another, an annular heating device surrounding and spaced from the rod and adapted to form the molten zone in the rod, means for displacing the heating device along the rod so as to pass the molten zone along the rod, means for rotating at least one of the end holders about its substantially vertical axis, means for displacing one of the end holders in a direction transverse to the axis thereof so that the recrystallized rod portion is formed with a specific diameter extending in direction toward the annular heating device, and means for rotating the supply rod portion about an axis eccentric to the axis of the supply rod portion.
  • Our invention relates to method and apparatus for crucible-free zone melting a crystalline rod, especially of semiconductor material.
  • One of the end holders is displaced ice laterally in a direction transverse to the vertical axis of the rod and of the annular heating device, the end holders being also respectively displaced in a vertical and similar direction so as to advance the first end holder toward the second end holder.
  • the second end holder is rotated until the rod portion located between the second end holder and the molten zone is formed to a specific diameter which may be larger than the inner diameter of the annular heating device, then, after forming the rod portion to the specific cross section, the second end holder is displaced only in a vertical direction relative to the heating device.
  • both holders of the rod are located in the same vertical axis.
  • the cross section of the rod portion recrystallizing from the melt continually increases.
  • the end holder thereof is maintained in its eccentric position and is thereafter only adjusted with regard to its vertical position relative to the other holder.
  • Apparatus for carrying out the foregoing method comprises substantially vertically spaced end holders supporting between them a vertically extending semiconductor rod having a recrystallized portion and a supply portion to be recrystallized divided by a molten zone, means for relatively displacing the end holders toward one another, an annular heating device surrounding and spaced from the rod and adapted to form the molten zone in the rod, means for displacing the heating device along the rod so as to pass the molten zone along the rod, means for rotating at least one of the end holders about its substantially vertical axis, means for displacing one of the end holders in a direction transverse to the axis thereof so that the recrystallized rod portion is formed with a specific diameter extending in direction toward the annular heating device, and means for rotating the supply rod portion about an axis eccentric to the axis of the supply rod portion.
  • the mechanism serving for producing the eccentric motion is considerably simplified. It is of particular importance for the method of our invention that due to the stirring motion of the eccentrically rotated supply rod portion to be crystallized, the molten zone is well intermixed, producing highly uniform radial resistance distribution over the rod cross section. Further in accordance with a feature of our invention, both end holders are rotated in opposite rotary directions. A particularly good turbulence and intermixture of the melting zone is obtained, which is very desirable for obtaining good crystal quality and radial resistance distribution.
  • FIG. 1 is an elevational view partly broken away and partly in section showing two phases during the practice of the method of the invention
  • FIG. 2 is an end view schematically showing the path of movement of the supply rod portion to be recrystallized
  • FIG. 3 is an elevational view partly in section of a rod holder connecting the rod to a rotary shaft in accordance with the invention
  • FIG. 4 is an upper end view of FIG. 3;
  • FIG. 5 is a diagrammatic view of apparatus for carrying out the method of the invention.
  • FIG. 1 a semiconductor rod 1 formed of a supply rod portion 2 which is to be melted and then recrystallized and a rod portion 3 that is resolidified or recrystallized from the melt.
  • a non-illustrated seed crystal which is fused thereto.
  • An induction heating coil 4 is spaced from and surrounds the semiconductor rod 1 and is energizable with a high-frequency current from a nonillustrated source for producing a melting zone 5 separating the recrystallized rod portion 3 from the supply rod portion 2 to be recrystallized.
  • the induction heating coil 4 can be moved upwardly or downwardly, as viewed in FIG.
  • the induction coil 4 serving as the heating device has a central axis M.
  • a drive shaft 6 for the supply rod portion 2 that is to be recrystallized is eccentrically inserted in the holder 7 of the rod portion 2 and is secured in the eccentric, substantially vertical position shown in FIG. 3.
  • the drive shaft 6 has a longitudinal axis E. Both rod portions 2 and 3 are rotated by drive mechanisms which are well known and are described hereinafter. At the same time, the recrystallizing rod portion 3 is laterally displaceable relative to the rod portion 2 and to the heating device 4.
  • the molten zone 4 is thereby well intermixed producing an exceptionally uniform radial resistance distribution over the rod cross section (Apz570%)
  • the eccentricity e of the recrystallizing rod portion 3 with respect to the supply rod portion 2 should be so great that no liquid material drips from the molten zone 4.
  • the eccentricity e can be substantially as much as 10 mm. for a recrystallizing rod portion 3 having a diameter of 35 mm.
  • the eccentricity 2 of the rotary axis E of the supply rod portion 2 to the geometrical axis M thereof is adjustable advantageously by the holder 7 (FIG. 3) described more fully hereinafter.
  • By varying the eccentricity e the stirring effect of the supply rod portion 2 is greatly varied.
  • the additional area traversed by the supply rod portion 2, besides its own cross-sectional area, is shown by the hatching in FIG. 2.
  • the rotary speed of the recrystallizing rod portion 3 is between '8 and 70 rpm. for a rod diameter of 33 millimeters, and is preferably 25 r.p.m.
  • the rotary speed of the rod portion 2 supplying the melt and which is to be recrystallized is between 8 and r.p.m. for a rod diameter of 27 mm., and is preferably 25 r.p.m.
  • the rod portion 2 is advantageously moved .in a direction toward the rod portion 3 at a speed of about 1.5 mm. per minute.
  • the heating device 4 is moved in a direction opposite to the movement of the rod portion 2 upwardly as shown in FIG. 1 at a speed of 1 to 2 mm. per minute and preferably 1.8 mm. per minute.
  • the eccentricity 6 of the rod portion 2 is about 2 mm., whereas the eccentricity e of the rod portion 3 is set at about 8 mm.
  • the holder 7 is formed of two tubular portions 8 and 9 separated by a base or partition 10.
  • the rod portion 2 is inserted into one tubular portion 8 and preferably clamped therein.
  • Adjusting or set screws 13 are provided in two different planes 11 and 12 in the tubular portion 9 and serve for eccentrically holding the drive shaft 6 and for securing the rod portion 2 in vertical position.
  • the adjusting screws 13 disposed in the plane 11 serve for establishing the eccentricity e of the drive shaft '6, whereas the adjusting screws 13 disposed in the plane '12 are provided for securing the rod portion 2 in vertical position.
  • three adjusting screws 13 circumferentially spaced 120 apart from one another are provided in each of the planes 11 and 12.
  • both rod portions 2 and 3 can be axially displaced in the same direction at speeds that are predetermined with respect to one another in accordance with the desired rod dimensions.
  • both rod holders can be rotated in the same rotary direction.
  • the method of our invention is not limited to resolidifying or recrystallizing rod portions whose diameter is greater than the inner diameter of the heating device 4. It can, quite the contrary, be employed for producing recrystallizing rod portions having a diameter which is equal to or smaller than the diameter of the rod portion that is to be melted or recrystallized and/or the same as or smaller than the inner diameter of the heating device.
  • our method can also be instituted with advantage, when the recrystallizing rod portion is disposed coaxial to the center axis of the heating device.
  • the employment of the method of our invention is advantageous if the diameter of both rod portions is larger than the inner diameter of the heating device.
  • FIG. 5 The apparatus for carrying out the process of the invention is shown in FIG. 5.
  • a semiconductor rod comprising the supply portion 2 and recrystallized portion 3 to which a seed crystal is fused, is vertically supported by the end holders 101, 102.
  • a slider 103 displaceable on a rotary spindle 1104, has an extension 10 abutting the holder 101 so as to be able to displace the holder 101 and the rod portion 2 in either vertical direction depending on the direction of rotation of a reversible motor M
  • a reversible motor M is supported on the extension 105 and drives a shaft 6 for rotating the holder 101 and the rod portion 2 about an axis E eccentric to the geometrical axis M of the rod portion. 2.
  • the motor M is supported on a base 106 of the apparatus.
  • the holder 102 of the recrystallized rod portion 3 is rotatable by a motor M which has a displaceable shaft at one end of which the holder 102 is secured.
  • the motor M is fastened to a slide 107 which is horizontally displaceable by a rack and pinion mechanism driven by a motor M mounted on the base 106 whereby the holder 102 and the recrystallized rod portion 3 are displaceable in a direction transverse to the vertical axis of the rod.
  • a motor M also mounted on the base 106 drives a rotary spindle 108 provided with a spindle head that is in engagement with the displaceable shaft of the motor M for vertically displacing the holder 102 and the recrystallized rod portion 3.
  • the horizontal displacement distance of the recrystallized rod portion 3 is relatively small so that the relatively wide abutting surface of the head on the spindle 108 engages the displaceable shaft of motor M in all of the possible horizontally displaced positions of the slide 107 and the motor M secured thereto.
  • the apparatus of our invention is located in a vacuum or protective gas atmosphere in accordance with like apparatus described in Patents Nos. 2,972,525; 2,992,311 and 3,030,194.
  • Process of zone melting a semiconductor rod having, under process, a recrystallized portion and a supply portion to be recrystallized, each separated from the other by a molten zone which comprises supporting the rod substantially vertically by first and second holders respectively located at the free ends of the supply rod portion and the recrystallized rod portion, forming the molten zone in the rod with an annular heating device spaced from and surrounding the rod, relatively moving the rod and the heating device in a substantially vertical direction so as to pass the molten zone along the rod, rotating at least one of the end holders about the substantially vertical axis of the rod portion at the free end of which the end holder is located, relatively moving the end holders toward one another and laterally away from one another at predetermined speeds so as to increase the thickness of the recrystallized rod portion in a direction radially outwardly to the annular heating device and rotating the supply rod portion about an axis eccentric to the substantially vertical axis of the supply rod portion.
  • Apparatus for carrying out the foregoing method including substantially vertically spaced end holders supporting between them a vertically extending semiconductor rod having a recrystallized portion and a supply portion to be recrystallized divided by a molten zone, means for relatively displacing the end holders toward one another, an annular heating device surrounding and spaced from the rod and adapted to form the molten zone in the rod, means for displacing said heating device along the rod so as to pass the molten zone along the rod, means for rotating at least one of said end holders about its substantially vertical axis, means for displacing one of said end holders in a direction transverse to the axis thereof so that the recrystallized rod portion is formed with a specific diameter extending in direction toward said annular heating device, and means for rotating the supply rod portion about an axis eccentric to the axis of the supply rod portion.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
US658512A 1966-08-06 1967-08-04 Eccentric feed rotation in zone refining Expired - Lifetime US3561931A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES0105235 1966-08-06

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US3561931A true US3561931A (en) 1971-02-09

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US (1) US3561931A (de)
DE (1) DE1519897B2 (de)
GB (1) GB1164940A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846082A (en) * 1971-11-08 1974-11-05 Tyco Laboratories Inc Production of crystalline bodies of complex geometries
US3988197A (en) * 1973-11-22 1976-10-26 Siemens Aktiengesellschaft Crucible-free zone melting of semiconductor crystal rods including oscillation dampening
US4002523A (en) * 1973-09-12 1977-01-11 Texas Instruments Incorporated Dislocation-free growth of silicon semiconductor crystals with <110> orientation
US20070227189A1 (en) * 2004-03-29 2007-10-04 Kyocera Corporation Silicon Casting Apparatus and Method of Producing Silicon Ingot

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846082A (en) * 1971-11-08 1974-11-05 Tyco Laboratories Inc Production of crystalline bodies of complex geometries
US4002523A (en) * 1973-09-12 1977-01-11 Texas Instruments Incorporated Dislocation-free growth of silicon semiconductor crystals with <110> orientation
US3988197A (en) * 1973-11-22 1976-10-26 Siemens Aktiengesellschaft Crucible-free zone melting of semiconductor crystal rods including oscillation dampening
US20070227189A1 (en) * 2004-03-29 2007-10-04 Kyocera Corporation Silicon Casting Apparatus and Method of Producing Silicon Ingot
US7867334B2 (en) * 2004-03-29 2011-01-11 Kyocera Corporation Silicon casting apparatus and method of producing silicon ingot

Also Published As

Publication number Publication date
DE1519897B2 (de) 1974-07-18
GB1164940A (en) 1969-09-24
DE1519897A1 (de) 1972-02-10
DE1519897C3 (de) 1975-06-12

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