US3179502A - Method and means for floating-zone melting of rod-shaped bodies of crystallizable semiconducting or conducting material - Google Patents

Method and means for floating-zone melting of rod-shaped bodies of crystallizable semiconducting or conducting material Download PDF

Info

Publication number
US3179502A
US3179502A US180216A US18021662A US3179502A US 3179502 A US3179502 A US 3179502A US 180216 A US180216 A US 180216A US 18021662 A US18021662 A US 18021662A US 3179502 A US3179502 A US 3179502A
Authority
US
United States
Prior art keywords
zone
molten zone
rod
coil
molten
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
US180216A
Other languages
English (en)
Inventor
Rummel Theodor
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 and Halske AG
Siemens AG
Original Assignee
Siemens AG
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 AG filed Critical Siemens AG
Application granted granted Critical
Publication of US3179502A publication Critical patent/US3179502A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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

  • zs-sar My invention relates to method and means for the crucible-free zone melting of rod-shaped bodies consisting of crystallizable semiconducting or conducting material.
  • I relating to the cruciblefree zone melting of vertically held rods of conducting, or semiconducting crystallizable material such as silicon
  • I produce or maintain the molten zone by high-frequency induction heating and I further subject the rod immediately above and below the molten zone to two auxiliary inductive fields for jointly providing a controlled levitating action upon the molten zone, the two auxiliary fields having the same frequency but mutually opposed instantane ous poling relative to their respective effects on the rod axis at a location in the molten zone.
  • the inductive heater coil for producing the molten zone and the two auxiliary inductance coils for controlled levitation are mounted together to form a single assembly relative to which the molten zone has a given location during performance of the zone melting process, so that all three inductance coils travel together with the molten zone relative to the longitudinal axis of the rod while the zone melting is in progress.
  • the frequency of the alternating currents flowing through the auxiliary inductance coils above and below the molten zone are kept so low and the amplitudes of these respective currents are adjusted to such a high value that, on the one hand, the axial length of the molten zone is virtually determined only by the field of the heating coil and, on the other hand, the bulge due to gravity in the molten zone is displaced toward the middle height of the zone.
  • the molten zone it is preferable to pass the molten zone from above downward through the rod and to simultaneously take advantage of the resulting possibility that the contour angle at the upper freezing boundary of the molten zone, and consequently the cross section of the material recrystallizing out of the molten zone, can be adjusted by controlling or regulating the intensity of the current flowing through the upper one of the two auxiliary coils. It is also of advantage to give the power being transmitted from the inductive heating coil to the rod such a high rating that the axial length of the molten zone is considerably larger than, for example at least about twice as large as, the axial length of the inductive heater coil and the isothermal faces at the freezing boundaries of the molten zone are substantially planar. In this manner the semiconductor material crys-, tallizing out of the molten zone can be obtained in a condition of greatly minimized disclocations.
  • the inductive heater coil is energized by an alternating current of high amplitude and high frequency in comparison with the corresponding parameter values of the current in the auxiliary coils, so that the force which the field of the heater coil imposes upon the molten zone remains negligible in comparison with the resultant levitating action of the two other coils despite the high heating energy of the heater coil that determines the length of the molten zone.
  • FIG. 1 shows two inductance coils in operation rela tive to the molten zone of a rod as occurring with the prior methods mentioned above.
  • FIG. 2 is a comparative showing of three inductance coils acting upon a molten zone in accordance with the invention.
  • FIG. 3 shows schematically and by way of example a zone-melting device incorporating the coil assembly according to PEG. 2;
  • FIG. 4 is a schematic circuit diagram of the same device.
  • the invention is generally applicable to metals and semiconductors of any kind amenable to zone melting, it is preferably employed for the zone melting of semi conductor substances such as germanium and silicon.
  • a particular advantage is afforded by the invention when employing it for pulling silicon monocrystals.
  • a levitating field is provided by means of only one induction coil located beneath the heating coil, this type of operation results in the above-mentioned difficult operating conditions that afford an only small range of regulation. These conditions will be explained with reference to FIG. 1.
  • the molten zone 2 is kept iloating between the two solid portions 2. and l of a silicon rod.
  • the molten zone is produced or maintained by an inductive heater coil 3 and is supported by a levitating coil 4.
  • the supporting field presses the molten zone upwardly and produces a relatively large, outwardly open contour angle.
  • this contour angle has the effect of continuously enlarging the cross section of the material which reci'ystallizes out of the melt in monocrystalline constitution.
  • the increase in monocrystallinc cross section is the larger the more the contour angle departs from 189. It is therefore desirable to maintain at the freezing boundary a tangential or contour angle as close as possible to 180.
  • This coil assembly comprises the inductive heater coil 3 for producing the molten zone 2 and the levitating coil 4 described above with reference to 1 1G; 1, but is provided with an additional auxiliary inductance coil 5 which presses the upper'portion of the molten zone 2 downwardly while imposing no appreciable force upon the lower portion of the molten zone. in this manner the bulge of the molten zone is displaced toward the middle, which is particularly favorable for uniform recrystallization.
  • FIG. 3 shows the same coil assembly as FIG. 2.
  • the three coils 3, 4, 5 are rigidly mounted on a support 6 and consist preferably of copper tubing traversed by cooling water during operation.
  • the cooling water is supplied to the support 6, for example, through flexible hose connections, and the electric currents for the respective coils 3, 4, 5 are supplied to the support 6 through flexible cables.
  • the support 6 is shown engaged by a screw spindle 7 and the rod 1 is shown vertically mounted in holders 8 and 9.
  • the spindle '7 is driven from a suitable 7 electric motor (not shown) for moving the support 6 with the coil assembly downward during zone melting and subsequently returning the assembly at faster speed upwardly during an idle return motion, whereafter another zone pass can be performed if desired.
  • the illustrated device is preferably mounted within a processing vessel which may be filled with an inert gas or other protective atmosphere.
  • the heater coil 3 is connected to a high frequency source ill, such as a suitable electronic generator having a frequency in the megacycle range, and supplying a current in the order of 100 amps, for example.
  • the coils i and 5 are each connected to a radio-frequency source 12, for example an electronic generator having a frequency in the kilocycle range and a current rating higher than that of the generator ll.
  • Shown in FIG. 4 are a control rheostat 13 for adjustingthe amplitude of the current flowing through the heater coil 3, and corresponding rheostats M and 15 for adjusting the amplitudes of the respective current passing through the auxiliary inductance coils l and 5.
  • the levitating forces at a constant amplitude of the magnetic field strength in an electromagnetic alternating field increase in proportion a lower power of the frequency than the heating power. It is therefore possible by employing f elds of relatively low frequency to secure the required levitating action it the amplitude of the field strength is made sufficiently large. Then the lower frequency does not cause a more intensive heating of the rod to be zone-inelted, despite the large field amplitude. Conversely, the required heating can be secured at low field amplitudes if the frequcncy of the heating alternating field is kept sufficiently high.
  • the two auxiliary coils are traversed by respective currents of correspondingly high amplitude and low frequency, the current amplitude being so chosen that it is capable, despite the low frequency, of exerting the required force action upon the molten zone.
  • the choice of a correspondingly low frequency counteracts the otherwise expectable increase in heat supply to the molten zone.
  • the upper auxiliary coil takes care that the molten zone is not pressed against the upper boundary of the molten zone.
  • the effects of the two coils are so adapted to each other that the bulge of the molten zone due to gravity pressure becomes located at approximately the middle height of the zone.
  • the lower auxiliary coil supports the molten zone against gravity
  • the upper coil acts upon the molten zone in the same direction as gravity by pressing the zone downwardly
  • the two coils must be so dimensioned or be traversed by currents so rated that the force produced by the lower auxiliary coil has a considerably stronger axial component than the field of the upper coil because the lower coil must compensate gravity as well as a portion of the force effect due to the upper coil.
  • the particular frequency and current values can be chosen and adjusted in accordance with the requirements of the particular material and the dimensions of the particular rod to be processed.
  • the following example is illustrative, relating to the zone melting of silicon.
  • the rod diameter in this example was 18 min, the height of the molten zone 22 mm., its temperature about 1420 C.
  • the heating coil 3 consisted of two turns located vertically above one another as apparent in Pl-G. 2, in contrast to the single-plane spiral turns of the auxiliary coils 4 and 5.
  • the heater coil 3 was traversed by a current of A. and 4- mc.
  • the spacing of the in er edge of heater coil 3 from the rod axis was 17 mm.
  • the axial length of the heater winding was about 8 mm.
  • the lower auxiliar coil 4 surrounded the rod about 13 mm. beneath the lower boundary of the melting zone.
  • the inner edge of the lower coil 4 was likewise spaced 17 mm. from the rod axis.
  • the coil l constituting the main levitating coil' and consisting of six turns in a single plane, had an outer diameter of 47 mm. and was traversed by current of 300 A. and 10 kc.
  • the counter coil 5 was located approximately 8 mm. above the lower boundary of zone 2 and was energized by a 10 lrc. current of 200 A.
  • all coils are perferably made of copper tubing and are traversed by liquid coolant during operation.
  • the method for floating-zone melting a silicon rod which comprises supporting the molten zone in a vertically held silicon rod by two induction coils coaxially surrounding the rod above and below the molten zone, energizing the two coils by alternating currents of the same frequency to respectively produce downwardly and upwardly acting fields on the rod axis at the location of References Cited by the Examiner UNITED STATES PATENTS 2,686,864 8/54 Wroughton 75--10 2,686,865 8/54 Kelly 7510 2,897,329 7/59 Matare 7510 2,904,411 9/59 Pfann 148--1.6 2,905,798 9/59 Freutel 1481.6

Landscapes

  • 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)
  • Silicon Compounds (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
US180216A 1961-03-17 1962-03-16 Method and means for floating-zone melting of rod-shaped bodies of crystallizable semiconducting or conducting material Expired - Lifetime US3179502A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES73019A DE1212051B (de) 1961-03-17 1961-03-17 Verfahren zum tiegellosen Zonenschmelzen von Staeben aus Silicium

Publications (1)

Publication Number Publication Date
US3179502A true US3179502A (en) 1965-04-20

Family

ID=7503625

Family Applications (1)

Application Number Title Priority Date Filing Date
US180216A Expired - Lifetime US3179502A (en) 1961-03-17 1962-03-16 Method and means for floating-zone melting of rod-shaped bodies of crystallizable semiconducting or conducting material

Country Status (6)

Country Link
US (1) US3179502A (xx)
CH (1) CH430664A (xx)
DE (1) DE1212051B (xx)
FR (1) FR1317786A (xx)
GB (1) GB937190A (xx)
NL (1) NL274145A (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072556A (en) * 1969-11-29 1978-02-07 Siemens Aktiengesellschaft Device for crucible-free floating-zone melting of a crystalline rod and method of operating the same
US5427335A (en) * 1992-07-13 1995-06-27 The University Of Tennessee Research Corporation Method for producing extreme microgravity in extended volumes
WO2004113596A1 (de) * 2003-06-20 2004-12-29 Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V. Verfahren und vorrichtung zum ziehen von einkristallen durch zonenziehen

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1243642B (de) * 1963-04-27 1967-07-06 Siemens Ag Vorrichtung zum tiegelfreien Zonenschmelzen von Halbleitermaterial
EP0292920B1 (en) * 1987-05-25 1992-07-29 Shin-Etsu Handotai Company Limited Rf induction heating apparatus

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2686864A (en) * 1951-01-17 1954-08-17 Westinghouse Electric Corp Magnetic levitation and heating of conductive materials
US2686865A (en) * 1951-10-20 1954-08-17 Westinghouse Electric Corp Stabilizing molten material during magnetic levitation and heating thereof
US2897329A (en) * 1957-09-23 1959-07-28 Sylvania Electric Prod Zone melting apparatus
US2904411A (en) * 1955-06-17 1959-09-15 Bell Telephone Labor Inc Suspension of liquid material
US2905798A (en) * 1958-09-15 1959-09-22 Lindberg Eng Co Induction heating apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2686864A (en) * 1951-01-17 1954-08-17 Westinghouse Electric Corp Magnetic levitation and heating of conductive materials
US2686865A (en) * 1951-10-20 1954-08-17 Westinghouse Electric Corp Stabilizing molten material during magnetic levitation and heating thereof
US2904411A (en) * 1955-06-17 1959-09-15 Bell Telephone Labor Inc Suspension of liquid material
US2897329A (en) * 1957-09-23 1959-07-28 Sylvania Electric Prod Zone melting apparatus
US2905798A (en) * 1958-09-15 1959-09-22 Lindberg Eng Co Induction heating apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4072556A (en) * 1969-11-29 1978-02-07 Siemens Aktiengesellschaft Device for crucible-free floating-zone melting of a crystalline rod and method of operating the same
US5427335A (en) * 1992-07-13 1995-06-27 The University Of Tennessee Research Corporation Method for producing extreme microgravity in extended volumes
US5887827A (en) * 1992-07-13 1999-03-30 Sanders; Alvin Joyner Method for producing extreme microgravity in extended volumes
WO2004113596A1 (de) * 2003-06-20 2004-12-29 Leibniz-Institut Für Festkörper- Und Werkstoffforschung Dresden E.V. Verfahren und vorrichtung zum ziehen von einkristallen durch zonenziehen

Also Published As

Publication number Publication date
FR1317786A (xx) 1963-05-08
NL274145A (xx)
GB937190A (en) 1963-09-18
DE1212051B (de) 1966-03-10
CH430664A (de) 1967-02-28

Similar Documents

Publication Publication Date Title
US2905798A (en) Induction heating apparatus
US3234012A (en) Method for remelting a rod of crystallizable material by crucible-free zonemelting
US2972525A (en) Crucible-free zone melting method and apparatus for producing and processing a rod-shaped body of crystalline substance, particularly semiconductor substance
US2686865A (en) Stabilizing molten material during magnetic levitation and heating thereof
US4572812A (en) Method and apparatus for casting conductive and semiconductive materials
US2773923A (en) Zone-refining apparatus
US3258314A (en) Method for interior zone melting of a crystalline rod
US20120236898A1 (en) Open Bottom Electric Induction Cold Crucible for Use in Electromagnetic Casting of Ingots
US3108169A (en) Device for floating zone-melting of semiconductor rods
US3179502A (en) Method and means for floating-zone melting of rod-shaped bodies of crystallizable semiconducting or conducting material
JPH0412083A (ja) シリコン単結晶製造方法
US2855335A (en) Method of purifying semiconductor material
US3023091A (en) Methods of heating and levitating molten material
US3275417A (en) Production of dislocation-free silicon single crystals
US5868832A (en) Magnetic field generation
US4358416A (en) Apparatus and process for cooling and solidifying molten material being electromagnetically cast
Buehler Contribution to the floating zone refining of silicon
US3397042A (en) Production of dislocation-free silicon single crystals
US3060123A (en) Method of processing semiconductive materials
JPS5850953B2 (ja) 結晶成長法
CN116479517A (zh) 用于igbt的低氧单晶硅的制备方法
US3100250A (en) Zone melting apparatus
US3124633A (en) Certificate of correction
US3310384A (en) Method and apparatus for cruciblefree zone melting
GB843800A (en) Improvements in or relating to methods of treating bodies of material so as to controla solid-liquid interface therein