US3265470A - Method and apparatus for floating-zone melting of semiconductor material - Google Patents

Method and apparatus for floating-zone melting of semiconductor material Download PDF

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US3265470A
US3265470A US49330A US4933060A US3265470A US 3265470 A US3265470 A US 3265470A US 49330 A US49330 A US 49330A US 4933060 A US4933060 A US 4933060A US 3265470 A US3265470 A US 3265470A
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Prior art keywords
rod
frequency
generator
coil
current
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US49330A
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English (en)
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Keller Wolfgang
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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
    • C30B13/28—Controlling or regulating
    • C30B13/30—Stabilisation or shape controlling of the molten zone, e.g. by concentrators, by electromagnetic fields; Controlling the section of the crystal
    • 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
    • H05B6/06—Control, e.g. of temperature, of power
    • 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
    • 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
    • Y10T117/1004—Apparatus with means for measuring, testing, or sensing
    • Y10T117/1008—Apparatus with means for measuring, testing, or sensing with responsive control 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
    • 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

Definitions

  • Ger- My invention relates to a method and apparatus for the crucible-free, floating-zone meltin of semiconductor material aceor'dingto which a melting zone between the two ends of a semiconductor rod is passed longitudinally along the rod, the zone being heated by means of an inductance coil which surrounds. the rod and which is energized by a high-frequency generator.
  • My invention relates more particularly to a method and apparatus for processing semiconductor rods disclosed in the application, Serial No. 806,174, filed April 13, 1959,- of Th. Rummel, Keller and H. F. Quast, now Patent No. 2,913,561, granted November 17, 1958.
  • the diameter-dependent heating current to the inductancecoil is used for controlling a device capable of varying the spacing between the two holders in which the respective rod ends are held. Said controlled device moves the two holders toward or away from eachother until the current flowing in the highfrequency coil, upon departure from a datum value, again assumes that value.
  • the desired rod diameter is secured by controlling and varying the frequency of the high-frequency generator furnishing the current for energizing the induction heater coil that produces the travelling molten zone.
  • desired rod diameter is obtained by controlling and varying the heating circuit frequency or heating current power while changing the capacitance of the heating circuit.
  • the desired rod diameter is obtained by any type of variation in the relation between the oscillatory generator circuit and the heating circuit. variation of the coupling between the generator circuit and heating circuit, While maintaining the other parameter values of the two circuits constant.
  • FIG. 1 illustrates, schematically, a device and circuit diagram of equipment for controlling and regulating the rod diameter, according to the invention. 7
  • FIG. 2 is the circuit diagram of a high-frequency generator applicable in a control and regulating system ac cording to FIG. 1.
  • FIG. 3 is an explanatorydiagram relating to resonance conditions in the induction heating circuit.
  • FIG. 5 is a graph explanatory of a control program applicable for the purposes of the invention.
  • FIG. 6. illustrates schematically another apparatus for performing the method according to the invention.
  • FIG. 7 and FIG. 8 illustrate modifications of the in duction heating circuit applicable in apparatus according to FIG. 1 or FIG. 6.
  • I include in such types the 1 by induction heating.
  • a semiconductor rod 2 such as silicon
  • the upper holder 4 is axially displaceable.
  • the lower holder 3 is axially fixed but may be rotatable about its axis.
  • An induction heater coil 5 surrounds an axially narrow zone 6 of the semiconductor rod for melting it
  • a capacitor 7 is connected parallel to coil 5.
  • the coil 5 and the capacitor 7 form together a secondary oscillatory (tank) circuit, hereafter called heating circuit which is coupled to the output terminals 8 of a high-frequency generator 9.
  • the high-frequency generator preferably operates on a flank of the resonance curve of the heating circuit.
  • the generator 9 is energized at its input terminals 10 from a direct-current supply.
  • a rotatable knob 11 permits adjusting the frequency of the generator.
  • a high-frequency generator suitable for the purposes of theinvention will bedescribed below with reference to FIG. 2 and its performance will be explained with reference to FIG. 3.
  • the anode (output) current of the high-frequency generator 9 is dependent upon the power consumed by the heating circuit and hence is also dependent upon the diameter of the semiconductor. rod 2, because a change in rod diameter causes a change in the degree of coupling between the inductance coil 5 and the molten zone 6.
  • Such a variation of high-frequency current isindicated by an instrument 12 and produces a corresponding voltage drop along a resistor 13.
  • This resistor is to be adjusted so that the generator output current obtaining at the desired diameter of the semiconductor rod, produces in resistor 13 a voltage drop equal to the voltage of a compensating' voltage source or battery 14.
  • a polarized relay 15 in the cornpensating' circuit is inactive so that its cont-acts 16 are open.
  • the anode or output current of the generator 9 also changes and hence causes a corresponding change in voltage drop of resistor 13.
  • the relay 15 attracts its armature (not shown) and the contacts 16 connect a reversible motor 17 for rotation in a given direction.
  • the motor 17 drives a pinion 18 meshing with a rack 19, which displaces the upper rod holder 4, so that the upper holder 4 moves either downward or upward.
  • the motor 17 will always run in the proper direction, namely so that when the rod diameter tends to become too large, a stretching of the melting zone occurs, whereas the melting zone is narrowed and widened when the rod diameter tends to become too small. In this manner, a defined and predetermined constant diameter of the semiconductor rod is secured during zone melting operation.
  • FIG. 2 illustrates details of a high-frequency generator suitable for the invention.
  • the high-frequency generator is energized at terminals 10 from a direct-current source of constant voltage and includes a tank circuit consisting of a capacitor 20 and an inductance coil 21. This tank circuit determines the frequency of the generator output voltage, and is connectedin the plate circuit of a triode 22.
  • the above mentioned lR dr op resistor 13 is connectedin the plate circuit in series relation to the cathode of tube 22. As mentioned, the voltage-drop of resistor 13 is proportional to the anode current of the generator.
  • the heating circuit comprising the heater coil and the capacitor 7, is coupled with the generator circuit, for example inductively, as shown in FIG. 2.
  • the inductance coil 21 is provided with a secondary winding 210 from which the heating circuit is energized.
  • the capacitor 20 is adjustable and may be designed as a rotary capacitor device whose rotary electrode member is connected with the knob'll shown in FIG. 1. A high-frequency range of 1 to 5 megacycles per' second is particularly suitable for the zone meltingoperation.
  • the diameter of the rod to be processed may be 18 mm., for example.
  • the highfrequency generator is preferably operated on a flank of its resonance curve.
  • the resonance curve is exemplified in FIG. 3 where the abscissa denotes frequency (f), and the ordinate denotes current I or voltage U.
  • the resonance curve may represent the frequency characteristic of the heating circuit 5, 7.
  • the high-frequency generator preferably operates not in the direct vicinity of the resonance frequency fr, but along a flank portion of the resonance wave, preferably the frontal flank as shown in FIG. 3.
  • the generator frequency fg increases, the current in the heating circuit likewise increases.
  • the generator frequency ,fg declines, the heating current and hence the heating power likewise declines.
  • a m-onocrystal can be pulled from a polycrystalline semiconductor rod by floating zone melting when fusing to one end of the polycrystalline rod a monocrystalline seed whose cross section is considerably smaller than that of the rod to be processed.
  • This method requires passing a melting zone repeatedly from the seed along the r od.
  • This method being an improvement of a similar method in which the seed crystal has the same or nearly the same diameter as the semiconductor rod to be processed, has the advantage that the transfer of heat from the melting zone through the small cross section of the seed to the rod ,holder is greatly reduced with the result that the temperature gradient, in the rod portion immediately adjacent to the fusion junction between seed and rod is diminished. This in turn reduces the occurrence of lattice defections in the recrystallizing semiconductor material, thus improving the qu-ality of the product.
  • the method according to the present invention is performed while thus using a seed crystal of much smaller cross section than the semiconductor rod, difiiculties are encountered.
  • the shape of the transition between the semiconductor rod of normal thickness and the said much thinner seed crystal is not preserved.
  • the seed crystal becomes thickened.
  • the cross section of the seed crystal is equalized with the cross section of the rod proper, thus sacrificing the above-mentioned advantages of the thin seed crystal,- namely the reduced heat losses, the reduced transfer of impurities from the seed crystal to the rod, and the reduced issuance of lattice defections from the v.seed crystal into the rod.
  • the device which displaces the two rod holders toward or away from each other is made inactive and the generator frequency and/or the current supplied to the inductance heater coil is adjusted by hand while observing the melting zone. Thereafter the method according to the present invention for obtaining a constant and predetermined rod cross section isv initiated only after the melting zone has travelled out of the range where the seed crystal is fused to the rod. This is to be repeated at the beginning of each following pass of the melting zone.
  • the transition of the melting zone from the thin seed crystal to the thicker semiconductor rod is controlled by an auxiliary device in accordance with a predetermined control program governing the relation of the. generator frequency to the current supplied to the inductance heater coil.
  • FIG. 4 shows the semiconductor rod 102, the seed crystal 103 of much smaller diameter cross section, and the induction heater coil 104 which surrounds a melting zone 105.
  • the heater coil is preferably a spiral coil, comprising one coil layer in the axial direction, as described in the Keller and Emeis co-assi-gned application Serial No. 23,535 filed April 20, 1960. It may consist of copper tubing traversed by cooling water during operation.
  • An arrow x indicates the travelling direction of the heater coil 104 relative to the semiconductor rod 102 during a zone-melting pass.
  • the diagram according to FIG. 5 indicates the required relation between the generator frequency fg, or the heating current I to the travel path x of the heater coil, within a travelling range extending from the fusion junction of the rod with the thin seed crystal (x up to the location (x in the rod where, for obtaining stable conditions of the melting zone, the full constant cross section of the semi-conductor rod 102 is reached.
  • a melting zone is produced in the vicinity of the thin seed crystal 103.
  • the heater coil is supplied with current corresponding to the initial current value shown at location x of the diagram.
  • the generator frequency jg generally also coresponds to the value shown at the same location x in FIG. 5.
  • the generator frequency is regulated and hence fluctuates a little while the semi-conductor material is being heated up.
  • the generator frequency jg is controlled to steadily increase up to the value indicated at location x corresponding to the normal diameter of the semiconductor rod.
  • the heating current I may at first be somewhat reduced but must soon again resume its increase because, with an increase in diameter, greater quantities of material must be melted and the losses due to heat radiation increase. Thereafter the current gradually increases up to the value required at the location x
  • a semiconductor rod of 18mm. diameter and a seed crystal of 4.5 mm. were used. The distance between points x and x had a length of 45 mm.
  • the frequency fg at location x was 3,785 'kilocycles per second, and at the location x was 4,000 kc./s..
  • the apparatus shown in FIG. 6 is suitable for performing the above-described method.
  • the semiconductor rod 102 with a seed crystal 103 fused thereto, is mounted in two holders 106 and 107.
  • An induction heater coil 104 surrounds an axially narrow portion of the semiconductor rod to produce a melting zone 107.
  • Coil 104 is preferably formed as in FIG. 4.
  • the heater coil 104 is energized at its terminals 108 from a high-frequency generator 100, whose terminals 110 are connected to a suitable current source.
  • the frequency of the generator 109 is adjustable by means of a rotary knob 111.
  • the generator 109 may correspond to the one described above with reference to FIG. 2.
  • a capacitor 112 is connected parallel to the heater coil 104 for compensating the reactive current and forms a resonant heating circuit together with the coil 104 as explained above.
  • the heater coil is fastened on an insulating carrier 113,.which can be moved parallel to the longitudinal axis of the semiconductor rod with the aid of a rack 124 and a pinion 123.
  • the pinion is driven from a reversible electric motor 116.-
  • the anode or plate current of the high-frequency generator-109 depends upon the power consumption of the heating circuit, and hence upon the diameter of the semiconductor rod, because a change in rod diameter effects a change in the inductive coupling between coil 104 and molten zone 105.
  • a variation in plate current of the high-frequency generator is indicated by a measuring instrument 117 and causes a corresponding voltage drop in a resistor 118 which corresponds to the resistor 13 of FIGS. 1 and 2.
  • the resistor 118 is so adjusted that the plate current occurring at the desired diameter of the semiconductor rod produces a voltage drop in resistor 113 equal to the reference voltage of a battery 119. Under such compensated condition, the polarized relay 120 is inactive and the motor 112 is at rest.
  • the relay 120 is energized and closes its contacts 121 in one or the other direction depending upon the direction in which the rod diameter departs from the desired rod diameter tendsto become too small.
  • the motor 122 is energized to run in the proper direction.
  • the motor drives the rack 124 to move the upper rod holder 106 upwardly or downwardly.
  • the motor whenever energized will run in the direction required for stretching the molten zone when it tends to become too thick, and for widening the zone when the In this manner, an accurately defined and predetermined diameter of the semiconductor rod being processed is constrainedly obtained.
  • the parameter values namely the adjusted generator frequency and the voltage of the compensating battery 119, normally correlated to the normal rod diameter, must be changed to different values for operation in the just-mentioned range where maintenance of a constant cross section is not desirable. That is, care must be taken that the generator frequency and heating current assume the performance characteristic illustrated in FIG. 5 and explained'above.
  • the generator frequency can be varied, for example, by parallel connected capacitances.
  • the heating current can be variedby an auxiliary voltage added in the positive or negative sense to the voltage of the compensating battery 119. In the illustrated embodiment according to FIG.
  • a group of capacitors 125 are connected in parallel relation to the frequency-determining tank circuit of the highfrequency generator 109.
  • the selectively operable capacitors 125 are connected to the terminals 126 of the generator 109, the same terminals 126 being also indicated in FIG. 2.
  • a stepping switch operating preferably in synchronism with the drive for displacing the heating coil,
  • the drive motor 116 for the coil-displacing mechanism is connected by an electrornagnetically conitnolled clutch 127 with a shaft to which a contact arm 128 is connected.
  • the arm 128 sequentially connects the capacitors 125 to the generator terminals 126 in synchronism with the travelling motion of the heating coil.
  • auxiliary voltages are tapped off a voltage divider 131, energized by auxiliary direct-current voltage U.
  • the apparatus for performing the invention can be modified in various respects.
  • a rotary capacitor with correspondingly shaped electrode members can be used to afford a continuous variation.
  • the relation between the generator circuit and heating circuit may also be varied by maintaining the generator frequency constant and varying the capacitance of the resonant heating circuit.
  • the capacitor 7 described above with reference to FIG. 2 may be designed as a variable capacitor as shown at 7a in FIG. 7, and this capacitor may be adjusted to different capacitance values by means of a drive of the type exemplified in FIG. 6, to secure a change in capacitance according to the desired program and in synchronism with the travel of the heating coil.
  • the effect obtained by varying the relation between the generator oscillatory circuit and the heating circuit may also be obtained by varying the coupling between these two circuits, while maintaining the other parameters of the two oscillatory circuits constant.
  • the generator oscillatory circuit and the heating circuit may also be obtained by varying the coupling between these two circuits, while maintaining the other parameters of the two oscillatory circuits constant.
  • the clutch 127 (FIG. 6) is opened, Whereafter the contact arms 128 and 129 remain at standstill, in the illustrated positions.
  • the release of the clutch 127 may be efie'cted electrically, for example with the aid of a limit contact 138 which is actuated by a member 139 mounted on the insulating carrier 113 of the heater coil 104.
  • the member 139 closes the contact 138 and thereby energizes the actuating magnet 127a of the clutch 127 from a current source 140.
  • the coil carrier 113 may be provided with further switching means for cooperating with limit contacts in order to reverse the travelling direction of the heater coil (I refer to the report by E. Beuhler, entitled Contribution to the Floating-Zone Refining of Silicon, the Review of Scientific Instruments, volume 28, No. 6, June 1957, pages 453 to 460), for switching the heating power from a high value during the above-described regulation for upward travel of the coil, to a low value for downward travel so that only a glowing zone instead of a melting zone is maintained during downward travel.
  • limit contacts actuated by the travel of the coil carrier may serve to put the rotation of the lower rod holder 107 into and out of operation.
  • the individual control or relay circuits required for such purposes may be conventional and for that reason are not illustrated since they are not essential to the invention proper and are Within the scope of ordinary control engineering practices.
  • the tuned circuit employing said current for controlling a device which moves the two rod end portions relatively to each other so that the current in the high-frequency coil is maintained at a desired value, and further maintaining the rod diameter at an adjusted constant value by regulating the frequency of the high-frequency generator to control the heating power of the current supplied to the coil, the method being further characterized in that before starting the floating zone melting a thin seed crystal is fused to one end of the semiconductor rod, the seed having a smaller cross section than the rod, to minimize heat transfer therebetween, each pass of the melting zone through the semiconductor rod commencing in the seed crystal, the transition of the melting zone from the thin seed to the thick rod being controlled in accordance with a predetermined program for the generator frequency and
  • An apparatus for floating-zone melting of semiconductor material to produce a semiconductor rod comprising two holder means for opposite end portions of the rod to support the rod vertically, means for relative displacement of the holder means with respect to each other in an axial direction lengthwise of the rod, a high-frequency induction heater coil adapted for encircling the rod out of contact therewith, and to produce the floating molten zone therein, the coil having an axially limited dimension so as to produce a molten zone of a size sus-.
  • a heater circuit said heater circuit comprising said heater coil and a condenser connected across the coil, a high-frequency current generator having output terminals connected in said heater circuit, the current in said heater circuit being inherently subject to variation as the diameter of the encircled portion of the rod varies, due to a change in inductive coupling between the heater coil and the encircled molten zone, circuit means connected to said generator for carrying a current dependent upon the power consumed by the heating, an adjustable resistor connected in said circuit means, a control circuit means connected across the resistor, a constant direct compensating voltage source connected in said control circuit means in series with the resistor, a polarized relay connected for operation by said voltage source, means operated by said relay to operate the means for relative displacement of the holder means with respect to each other, the resistor being adjustable so that the generator output current existent with a
  • An apparatus for floating-zone melting of semiconductor material to produce a semiconductor rod comprising two holder means for opposite end portions of the rod to support the rod upstandingly, means for relative displacement of the holder means with respect to each other in an axial direction lengthwise of the rod, a high-frequency induction heater coil adapted for encircling the rod out of contact therewith, and to produce the floating molten zone therein, the coil having an axially limited dimension so as to produce a molten zone of a size sustainable by adhesion to the adjacent solid portion of the rod, means for relative displacement of the heater coil and the rod to cause displacement of the molten zone axially of the rod, a heater circuit, said heater circuit comprising said heater coil and a condenser connected across the coil, a high-frequency current generator having output terminals connected in said heater circuit, the current in said heater circuit being inherently subject to variation as the diameter of the encircled portion of the rod varies, due to a change in inductive coupling between the heater coil and the encircled
  • An apparatus for floating-zone melting of semiconductor material to produce a semiconductor rod comprising two holder means (106, 107) for opposite end portions of the rod to support the rod vertically, means (123, 124) for relative displacement of the holder means with respect to each other in an axial direction lengthwise of the rod, a high-frequency induction heater coil (104) adapated for encircling the rod out of contact therewith, and to produce the floating molten zone therein, the coil having an axially limited dimensiontso as to produce a molten zone of a size sustainable by adhesion to the adjacent solid portion of the rod, means (114, 115) for relative displacement of the heater coil and the rod to cause displacement of the molten zone axially of the rod, a heater circuit, said heater circuit comprising said heater coil and a condenser (112) connected across the coil, a high-frequency current generator (109) having means for varying the frequency of the current output thereof and having output terminals (108) connected in said heater circuit, the current in said heater circuit,
  • An apparatus for floating-zone melting of semiconductor material to produce a semiconductor rod comprising two holder means (106, -107) for opposite end portions of the rod to support the rod vertically, means (123, 124) for relative displacement of the holder means with respect to each other in an axial direction lengthwise of the rod, a high-frequency inductionheater coil (104) adapted for encircling the rod out of contact therewith, and to produce the floating molten zone therein, the coil having an axially limited dimension so as to produce a molten zone of a size sustainable by adhesion to the adjacent solid portion of the rod, means (114, 115) for relative displacement of the heater coil and the rod to cause displacement of the molten zone axially of the rod, a heater circuit, said heater circuit comprising said heater coil and a condenser (112) connected across the in the heating circuit increases and when the generator frequency is decreased the heating current and the heating power decline, said rod having a monocrystalline seed crystal fused thereto, the seed crystal being held by one of said said rod
  • An apparatus for floating zone melting processing of elongated semiconductor materials having a seed crystal of smaller cross section than the material fused at 'one end comprising, two spaced holder means for jointly supporting the semiconductor material by its one end and by the seed crystal, a high frequency induction heater coil adapted to encircle said material and forming part of a resonant tuned circuit, said coil having an axially limited dimension so as to produce a molten zone in said material of a size sustainable by adhesion to the adjacent solid portions of the material, regulating means for maintaining the cross section of the material and its diameter at a respective adjusted value; said regulating means including means for relative displacement of the coil and material to cause displacement of the molten zone, an adjustable high frequency generator having output terminals connected to said tuned circuit, control means responding to the frequency of said generator for displacing said holder means relative to each other along the longitudinal direction of said material whereby the rod diameter is maintained at an adjusted value; and means for varying the frequency of the generator away from the resonant frequency according to a given program

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • 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)
  • General Induction Heating (AREA)
  • Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US49330A 1959-08-17 1960-08-12 Method and apparatus for floating-zone melting of semiconductor material Expired - Lifetime US3265470A (en)

Applications Claiming Priority (2)

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DES64464A DE1215109B (de) 1959-08-17 1959-08-17 Verfahren zum tiegelfreien Zonenschmelzen von Halbleitermaterial
DES66492A DE1277813B (de) 1959-08-17 1959-12-31 Verfahren zum tiegelfreien Zonenschmelzen von Halbleitermaterial

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BE (1) BE594105A (sv)
CH (1) CH389249A (sv)
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US3321299A (en) * 1964-10-13 1967-05-23 Monsanto Co Apparatus and process for preparing semiconductor rods
US3436509A (en) * 1965-07-09 1969-04-01 Siemens Ag Device for inductively heating semiconductor material
US3446602A (en) * 1965-11-13 1969-05-27 Nippon Electric Co Flame fusion crystal growing employing vertically displaceable pedestal responsive to temperature
US3499736A (en) * 1965-10-06 1970-03-10 Philips Corp X-ray or gamma ray use in control of crystal diameter
US3660062A (en) * 1968-02-29 1972-05-02 Siemens Ag Method for crucible-free floating zone melting a crystalline rod, especially of semi-crystalline material
US3776703A (en) * 1970-11-30 1973-12-04 Texas Instruments Inc Method of growing 1-0-0 orientation high perfection single crystal silicon by adjusting a focus coil
US3880599A (en) * 1972-04-26 1975-04-29 Siemens Ag Control of rod diameter responsive to a plurality of corrected parameters
US3934983A (en) * 1972-09-08 1976-01-27 National Research Development Corporation Weighing cell apparatus for diameter control of a rotatable growing crystal
US4292487A (en) * 1977-07-07 1981-09-29 Topsil A/S Method for initiating the float zone melting of semiconductors
US4857689A (en) * 1988-03-23 1989-08-15 High Temperature Engineering Corporation Rapid thermal furnace for semiconductor processing

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US2508321A (en) * 1945-09-05 1950-05-16 Raymond M Wilmotte Method and means of controlling electronic heating
US2691732A (en) * 1948-12-07 1954-10-12 Westinghouse Electric Corp Radio frequency generator
US2868902A (en) * 1958-03-19 1959-01-13 Prec Metalsmiths Inc Induction heater control
US2913561A (en) * 1958-04-22 1959-11-17 Siemens Ag Processing semiconductor rods
US2972525A (en) * 1953-02-26 1961-02-21 Siemens Ag Crucible-free zone melting method and apparatus for producing and processing a rod-shaped body of crystalline substance, particularly semiconductor substance
US3030194A (en) * 1953-02-14 1962-04-17 Siemens Ag Processing of semiconductor devices
US3046379A (en) * 1959-09-11 1962-07-24 Siemens Ag Method and apparatus for zone melting of semiconductor material

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US2470443A (en) * 1944-07-21 1949-05-17 Mittelmann Eugene Means for and method of continuously matching and controlling power for high-frequency heating of reactive loads
US2508321A (en) * 1945-09-05 1950-05-16 Raymond M Wilmotte Method and means of controlling electronic heating
US2691732A (en) * 1948-12-07 1954-10-12 Westinghouse Electric Corp Radio frequency generator
US3030194A (en) * 1953-02-14 1962-04-17 Siemens Ag Processing of semiconductor devices
US2972525A (en) * 1953-02-26 1961-02-21 Siemens Ag Crucible-free zone melting method and apparatus for producing and processing a rod-shaped body of crystalline substance, particularly semiconductor substance
US2868902A (en) * 1958-03-19 1959-01-13 Prec Metalsmiths Inc Induction heater control
US2913561A (en) * 1958-04-22 1959-11-17 Siemens Ag Processing semiconductor rods
US3046379A (en) * 1959-09-11 1962-07-24 Siemens Ag Method and apparatus for zone melting of semiconductor material

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3321299A (en) * 1964-10-13 1967-05-23 Monsanto Co Apparatus and process for preparing semiconductor rods
US3436509A (en) * 1965-07-09 1969-04-01 Siemens Ag Device for inductively heating semiconductor material
US3499736A (en) * 1965-10-06 1970-03-10 Philips Corp X-ray or gamma ray use in control of crystal diameter
US3446602A (en) * 1965-11-13 1969-05-27 Nippon Electric Co Flame fusion crystal growing employing vertically displaceable pedestal responsive to temperature
US3660062A (en) * 1968-02-29 1972-05-02 Siemens Ag Method for crucible-free floating zone melting a crystalline rod, especially of semi-crystalline material
US3776703A (en) * 1970-11-30 1973-12-04 Texas Instruments Inc Method of growing 1-0-0 orientation high perfection single crystal silicon by adjusting a focus coil
US3880599A (en) * 1972-04-26 1975-04-29 Siemens Ag Control of rod diameter responsive to a plurality of corrected parameters
US3934983A (en) * 1972-09-08 1976-01-27 National Research Development Corporation Weighing cell apparatus for diameter control of a rotatable growing crystal
US4292487A (en) * 1977-07-07 1981-09-29 Topsil A/S Method for initiating the float zone melting of semiconductors
US4857689A (en) * 1988-03-23 1989-08-15 High Temperature Engineering Corporation Rapid thermal furnace for semiconductor processing

Also Published As

Publication number Publication date
DE1277813B (de) 1968-09-19
BE594105A (sv)
NL135666C (sv)
NL252591A (sv)
CH389249A (de) 1965-03-15
DE1215109B (de) 1966-04-28
GB899688A (en) 1962-06-27

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