US3563810A - Method for reducing the cross section of semiconductor rods by molten-zone stretching - Google Patents

Method for reducing the cross section of semiconductor rods by molten-zone stretching Download PDF

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Publication number
US3563810A
US3563810A US840105A US3563810DA US3563810A US 3563810 A US3563810 A US 3563810A US 840105 A US840105 A US 840105A US 3563810D A US3563810D A US 3563810DA US 3563810 A US3563810 A US 3563810A
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US
United States
Prior art keywords
coil
rod
zone
diameter
turns
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
US840105A
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English (en)
Inventor
Wolfgang Keller
Herbert Kramer
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 AG
Siemens Corp
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Siemens Corp
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Filing date
Publication date
Application filed by Siemens Corp filed Critical Siemens Corp
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Publication of US3563810A publication Critical patent/US3563810A/en
Anticipated expiration legal-status Critical
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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
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C30B15/08—Downward pulling
    • 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
    • Y10S117/91—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
    • 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
    • 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]

Definitions

  • Our invention relates to a method and means for reducing the cross section of semiconductor rods by subjecting them to floating zone melting and simultaneously stretching the molten zone by moving one end of the rod away from the other.
  • This method and suitable apparatus for its performance are known from Pats. 3,030,194.
  • a vertically mounted semiconductor rod secured at both ends in respective holders, is surrounded by a heater which produces an axially narrow molten zone in the rod while the rod holders are being moved away from each other thus stretching the molten zone and reducing the cross section of the recrystallizing rod.
  • the ultimate rod can be sliced into semiconductor plates of the size required for the production of electronic semiconductor devices, thus eliminating the time consuming and wasteful subdivision of slices whose cross section is larger than needed.
  • the heating of the molten zone is effected by means of an annular strip of tungsten traversed by electrical current to assume a temperature of about 2000 C.
  • the transfer of heat from the heater to the semiconductor rod is by radiation.
  • the attainable maximum reduction in cross section is mm.
  • the induction coil has the shape of a flat spiral.
  • semiconductor rods having a diameter of more than 25 mm. can readily be processed into thinner rods of monocrystalline constitution.
  • FIGS. 1, 2 and 3 respectively different embodiments of the invention by way of example.
  • an induction heater coil 2 surrounds the bottom portion of a molten zone 3 between an upper, thick rod portion 4 and a lower, thin rod portion 5.
  • the upper end of portion 4 is secured in a holder, and the lower end of portion 5 is likewise secured in a holder (both holders not shown) which are being moved apart during the zone-melting operation.
  • the coil 2 is designed as a flat spiral.
  • the inner winding turns of coil 2 are located vertically beneath the thick rod portion 4 and thus impose a levitating action upon the molten zone 3 by means of the magnetic field of the coil.
  • the molten zone is thus sustained in its position and much better prevented from dripping off than is the case in the apparatus previously known.
  • the thick rod 4 processed according to FIG. 1 may have a diameter of 40 mm. and the thin rod portion 5 recrystallizing from the molten zone 3 may have a diameter of 20 mm. With an inner coil diameter of about 25 mm., the levitating action of the magnetic field is ample for securing a stable zone-stretching operation.
  • the operation can be performed in known manner in vacuum or in a protective gas. Preferably applied is a vacuum.
  • the travel of the molten zone relative to the semiconductor rod is produced by moving the heater coil, or by moving the rod holders with respect to the heater coil which then may remain fixed.
  • the two rod portions 4 and 5 must move at respectively different speeds. That is, with a fixed heater coil 2, the thick rod portion 4 is to be moved downward at relatively low speed toward the coil 2, while simultaneously the thin rod portion 5 is pulled downwardly at a correspondingly higher speed. For example, with a reduction from 40 to 20 mm. in diameter, the thin rod portion must move at four times the speed of the thick portion relative to the heater coil.
  • the method can be performed also by maintaining the upper rod portion 4 at rest and moving only the lower portion, in which case the heater coil 2 must also be moved.
  • FIG. 2 shows a funnel-shaped heater coil 2 whose levitating efiect has likewise been found to be excellent.
  • FIG. 3 shows the lower end of the thick rod 4 which has been given a frustoconical or somewhat pointed shape by grinding or other suitable mechanical machining.
  • the thick rod 4 consists for example of polycrystalline silicon or other semiconductor material produced by pyrolytic precipitation from the gaseous phase.
  • a thin crystal seed 5a which is monocrystalline and which is to be fused to the lower end of the thick rod 4 when commencing the above-described zone-stretching operation.
  • the improvement which comprises placing around the top of a thin crystal seed an induction heater coil having turns of a diameter larger than the thickness of the thin crystal seed, forming the lower end of a thick rod having a diameter greater than 25 mm. and greater than the diameter of a plurality of inner turns of the coil but smaller than the diameter of at least one of the outer turns of the coil approximately into the shape of the molten zone to be produced by the coil, contacting the lower end of the thick rod with the top of the seed and heating the junction thereof with the coil so that the turns of the coil are positioned vertically beneath the thick portion, and thereafter commencing the zone melting and stretching operation.
  • Method according to claim 1 which comprises sharpening the lower end of the thick rod to a substantially conical shape before commencing the zone melting and stretching operation.

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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)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US840105A 1963-07-13 1969-06-12 Method for reducing the cross section of semiconductor rods by molten-zone stretching Expired - Lifetime US3563810A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DES0086157 1963-07-13
DES0099116 1965-08-28

Publications (1)

Publication Number Publication Date
US3563810A true US3563810A (en) 1971-02-16

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ID=25997302

Family Applications (1)

Application Number Title Priority Date Filing Date
US840105A Expired - Lifetime US3563810A (en) 1963-07-13 1969-06-12 Method for reducing the cross section of semiconductor rods by molten-zone stretching

Country Status (6)

Country Link
US (1) US3563810A (da)
BE (2) BE650386A (da)
CH (1) CH407959A (da)
DE (2) DE1719021B1 (da)
DK (1) DK112794B (da)
GB (2) GB1012998A (da)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59190300A (ja) * 1983-04-08 1984-10-29 Hitachi Ltd 半導体製造方法および装置
DE3433458A1 (de) * 1984-09-12 1986-03-20 Leybold-Heraeus GmbH, 5000 Köln Verfahren und vorrichtung zum abschmelzen von stangenfoermigem material mittels einer induktionsspule

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT194444B (de) * 1953-02-26 1958-01-10 Siemens Ag Verfahren und Einrichtung zur Behandlung einer längserstreckten Halbleiterkristallanordnung
NL252060A (da) * 1959-05-29

Also Published As

Publication number Publication date
GB1084930A (en) 1967-09-27
DE1519879A1 (de) 1970-02-26
CH407959A (de) 1966-02-28
DE1719021B1 (de) 1969-09-11
BE650386A (da) 1965-01-11
GB1012998A (en) 1965-12-15
DE1519879B2 (de) 1973-08-16
DK112794B (da) 1969-01-20
BE685925A (da) 1967-02-24
DE1519879C3 (de) 1974-05-09

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