US3649210A - Apparatus for crucible-free zone-melting of crystalline materials - Google Patents

Apparatus for crucible-free zone-melting of crystalline materials Download PDF

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Publication number
US3649210A
US3649210A US838026A US3649210DA US3649210A US 3649210 A US3649210 A US 3649210A US 838026 A US838026 A US 838026A US 3649210D A US3649210D A US 3649210DA US 3649210 A US3649210 A US 3649210A
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US
United States
Prior art keywords
rod
melting
zone
ring
heating device
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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
US838026A
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English (en)
Inventor
Wolfgang Keller
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 AG
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Siemens AG
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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
    • C30B13/16—Heating of the molten zone
    • 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
    • C30B13/28—Controlling or regulating
    • 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
    • Y10S117/90—Apparatus characterized by composition or treatment thereof, e.g. surface finish, surface coating
    • 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
    • Y10T117/1016—Apparatus with means for treating single-crystal [e.g., heat treating]
    • 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

  • I provide apparatus for crucible-free zone melting of rod-shaped members consisting of crystalline material, comprising at least one heating device for heating a portion of the rod-shaped member to the melting point thereof, and another heating device for afterheating the portion of the rod-shaped member crystallizing out of the melt.
  • the second heating device is in the form of a ring-shaped heat radiator surrounding the rod-shaped member, which is heated to a temperature that is nearly equal to the melting temperature of the material being processed.
  • the ring-shaped heat radiator or radiant heating ring is in the form of a hollow cylinder having a longitudinal dimension which is substantially equal to the length of the melting zone.
  • the radiant heating ring consists of graphite and has an inner diameter which is substantially double the diameter of the rod-shaped member.
  • FIG. 1 is a longitudinal schematic view of the device constructed in accordance with my invention
  • FIGS. 2 and 3 are diagrammatic views of'so-called lineage and slippage etch pit patterns respectively.
  • FIG. 4 is a further embodiment of the device shown in FIG. 1 which is particularly suitable for zone melting relatively thick rods.
  • a semiconductor rod 2 consisting of silicon, for example, wherein a melting zone 3 is produced with the aid of a heat-producing member 4 which, as shown, is in the form of an induction-heating coil. Due to relative motion between the rod 2 which is being processed and the heatproducing member 4, the melting zone 3 is passed through the rod 2 in the longitudinal direction thereof. If a monocrystalline seed crystal is fused to the end of the rod from which the melting zone pass begins, the rod finally formed by the zonemelting method in this manner is monocrystalline. By repeating the melting zone pass through the rod many times over, a purifying effect can be obtained; through zone levelling, the
  • impurities contained in the semiconductor rod can be distributed uniformly over the rod length and rod cross section.
  • the crystal quality of the material is also of particular significance.
  • the uniform distribution of the dislocations over the rod cross section and over the rod length is of importance in addition to the absolute value of the dislocation density.
  • Such dislocations can be rendered visible by providing samples of the material havingground surfaces which are then etched in a predetermined manner whereby the dislocations are visible as etch pits. Crystal imperfections in the form of serially aligned dislocations, for example in the form of lineages as shown in FIG. 2, and in the form of slippages as shown in FIG. 3, are particularly harmful.
  • serially aligned dislocations can be removed and that the absolute number of dislocations can be reduced by afterheating the semiconductor rod.
  • the serially aligned dislocations in the form of lineages have presented great difficulties particularly and have not until now been able to be removed or reduced to a measurable degree.
  • the graphite ring can either be directly heated by the passage of current therethrough or can be heated inductively.
  • the temperature of the graphite ring was kept above the melting point of the semiconductor material which was being processed, in the case of silicon (melting point 1,420 C.), it was maintained at a temperature of l,500 C., for example.
  • the height or longitudinal dimension of the cylindrical heat radiator 5 was substantially the same as the length of the melting zone 3.
  • FIG. 4 Another embodiment of the apparatus constructed in accordance with my invention, which is especially suitable for zone-melting thick ro ds, is shown in FIG. 4.
  • thick rods cannot be melted by induction-heating coils whose inner diameter is greater than the diameter of the rod, without resulting in the dripping of some of the molten material from the melting zone. Consequently, heating coils whose inner diameter is smaller than that of the rod diameter have been used, and the zone-melting process has been carried out so that first a thin seed crystal 7 is fused to the rod and then, by compressing the melt, the recrystallizing rod portion is increased in thickness to the desired cross section which can, for example, be the same as that of the rod portion which is being supplied to the melt.
  • the cross section of the recrystallizing rod is maintained substantially constant. Due to the fact that the melt is chocked in the vicinity of the heating coil and is supported by the magnetic field of the heating coil, the material of the melt is prevented from dripping, yet the crystal quality is reduced due to the highly nonuniform temperature gradients which are formed in the recrystallizing zone of the rod. With the device of the invention in the instant application, however, rod-shaped monocrystals of large cross section having good crystal quality can be obtained.
  • the radiant heating ring 5 should have an inner diameter considerably larger than the outer diameter of the rod being processed, that is, twice as large or larger. It is essential that the radiation heating ring exert'no damaging effects upon the semiconductor material; it must consequently consist of highly pure material such as graphite, for example, which is suitable for this purpose. Tungsten or molybdenum can also be used.
  • the radiation heating ring is advantageously heated to an elevated temperature in vacuum before its use in the zonemelting apparatus whereby impurities, especially on the surface thereof, which would otherwise vaporize from the radiation heating ring and penetrate into the semiconductor material, can be removed.
  • the semiconductor material on the side of the rod which is being melted can also be additionally heated, for example with the aid of a preheating coil 6 located above the heating coil 4 which serves to produce the melting zone. This feature also promotes the equalization of the temperature of the melt and thereby the maintenance of the growing boundary surface or freezing front in a single plane.
  • the dislocation density is reduced when a radiation heating ring of the aforementioned type is employed.
  • dislocation densities of substantially 120,000 etch pits per cm. are obtained whereas, under the very same conditions, the etch-pit density can be reduced to less than 20,000 per cm., for example 9,000 or 12,000, by employing the radiant heating ring 5.
  • the serially aligned dislocations in the form of lineages, as shown by etchpit arrays are completely removed.
  • the radiation heating ring is provided with a thick layer of a material which has a coefficient of expansion substantially the same as that of the base material on which it is coated, is stable to a temperature of 1,600 C. and can be produced with a great degree of purity.
  • a layer of carbon which is deposited by pyrolysis, for example, of a cyclical hydrocarbon compound, and which is known as hard carbon has proven to be successful.
  • Apparatus for crucible-free zone melting a rod-shaped member of crystalline material comprising at least one heating device substantially coaxially surrounding the rod-shaped member for heating a first portion of the rod-shaped member to the melting point thereof so as to form a melting zone therein, and another heating device for afterheating a second portion of the rod-shaped member directly adjacent to said melting zone and recrystallized therefrom, said other heating device comprising a ring-shaped heat radiator formed of graphite and substantially coaxially surrounding the portion of the rod-shaped member adjacent said melting zone, and means for heating said radiator to a temperature greater than the melting temperature of the crystalline material and at most exceeding the melting temperature to such extent that the molten zone remains located outside the portion of the rodshaped member surrounded by the heat radiator.
  • radiator is in the form of a hollow cylinder having a longitudinal dimension substantially equal to the longitudinal dimension of the melting zone.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
US838026A 1965-07-10 1969-06-20 Apparatus for crucible-free zone-melting of crystalline materials Expired - Lifetime US3649210A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DES98119A DE1275996B (de) 1965-07-10 1965-07-10 Vorrichtung zum tiegelfreien Zonenschmelzen
DES0103418 1966-04-26
US83802669A 1969-06-20 1969-06-20

Publications (1)

Publication Number Publication Date
US3649210A true US3649210A (en) 1972-03-14

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Family Applications (1)

Application Number Title Priority Date Filing Date
US838026A Expired - Lifetime US3649210A (en) 1965-07-10 1969-06-20 Apparatus for crucible-free zone-melting of crystalline materials

Country Status (7)

Country Link
US (1) US3649210A (fi)
BE (1) BE683853A (fi)
CH (1) CH435207A (fi)
DE (2) DE1275996B (fi)
GB (1) GB1148007A (fi)
NL (1) NL6609450A (fi)
SE (1) SE335852B (fi)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935059A (en) * 1969-07-21 1976-01-27 U.S. Philips Corporation Method of producing single crystals of semiconductor material by floating-zone melting
US20150203987A1 (en) * 2012-08-02 2015-07-23 Siltronic Ag Device for producing a monocrystal by crystallizing said monocrystal in a melting area
US20160115619A1 (en) * 2013-04-25 2016-04-28 Zhejiang Jingsheng M & E Co., Ltd. Zone melting furnace thermal field with dual power heating function and heat preservation method
US10138573B2 (en) * 2013-04-25 2018-11-27 Zhejiang Jingsheng M & E Co., Ltd Auxiliary heating device for zone melting furnace and heat preservation method for single crystal rod thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2932562A (en) * 1956-12-27 1960-04-12 Bell Telephone Labor Inc Zone-melting with joule heat
CA674121A (en) * 1963-11-12 Siemens-Schuckertwerke Aktiengesellschaft Method and apparatus for producing a strip of hyperpure semiconductor material
US3121619A (en) * 1959-10-19 1964-02-18 Philips Corp Zone-melting method and apparatus
US3258314A (en) * 1963-04-12 1966-06-28 Westinghouse Electric Corp Method for interior zone melting of a crystalline rod
US3271115A (en) * 1963-03-29 1966-09-06 Siemens Ag Apparatus for crucible-free zone melting of semiconductor material

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1188042B (de) * 1954-01-29 1965-03-04 Siemens Ag Vorrichtung zum tiegellosen Zonenschmelzen eines stabfoermigen kristallinen Halbleiterkoerpers
DE1044768B (de) * 1954-03-02 1958-11-27 Siemens Ag Verfahren und Vorrichtung zum Ziehen eines stabfoermigen kristallinen Koerpers, vorzugsweise Halbleiterkoerpers
DE1147206B (de) * 1961-10-02 1963-04-18 Siemens Ag Verfahren zum Herstellen stabfoermiger Siliciumeinkristalle mit einer mittleren Versetzungsdichte durch tiegelloses Zonenschmelzen

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA674121A (en) * 1963-11-12 Siemens-Schuckertwerke Aktiengesellschaft Method and apparatus for producing a strip of hyperpure semiconductor material
US2932562A (en) * 1956-12-27 1960-04-12 Bell Telephone Labor Inc Zone-melting with joule heat
US3121619A (en) * 1959-10-19 1964-02-18 Philips Corp Zone-melting method and apparatus
US3271115A (en) * 1963-03-29 1966-09-06 Siemens Ag Apparatus for crucible-free zone melting of semiconductor material
US3258314A (en) * 1963-04-12 1966-06-28 Westinghouse Electric Corp Method for interior zone melting of a crystalline rod

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935059A (en) * 1969-07-21 1976-01-27 U.S. Philips Corporation Method of producing single crystals of semiconductor material by floating-zone melting
US20150203987A1 (en) * 2012-08-02 2015-07-23 Siltronic Ag Device for producing a monocrystal by crystallizing said monocrystal in a melting area
US9932690B2 (en) * 2012-08-02 2018-04-03 Siltronic Ag Device for producing a monocrystal by crystallizing said monocrystal in a melting area
US20160115619A1 (en) * 2013-04-25 2016-04-28 Zhejiang Jingsheng M & E Co., Ltd. Zone melting furnace thermal field with dual power heating function and heat preservation method
US9797062B2 (en) * 2013-04-25 2017-10-24 Zhejiang Jingsheng M & E Co., Ltd Zone melting furnace thermal field with dual power heating function and heat preservation method
US10138573B2 (en) * 2013-04-25 2018-11-27 Zhejiang Jingsheng M & E Co., Ltd Auxiliary heating device for zone melting furnace and heat preservation method for single crystal rod thereof

Also Published As

Publication number Publication date
BE683853A (fi) 1967-01-09
NL6609450A (fi) 1967-01-11
DE1519889A1 (de) 1969-08-28
DE1275996B (de) 1968-08-29
CH435207A (de) 1967-05-15
SE335852B (fi) 1971-06-14
DE1519889B2 (de) 1970-10-15
GB1148007A (en) 1969-04-10

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