US3259467A - Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in acrucible - Google Patents

Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in acrucible Download PDF

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Publication number
US3259467A
US3259467A US327659A US32765963A US3259467A US 3259467 A US3259467 A US 3259467A US 327659 A US327659 A US 327659A US 32765963 A US32765963 A US 32765963A US 3259467 A US3259467 A US 3259467A
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United States
Prior art keywords
crystal
pulling
rod
melt
crucible
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Expired - Lifetime
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US327659A
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English (en)
Inventor
Rummel Theodor
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Siemens and Halske AG
Siemens Corp
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Siemens Corp
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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
    • C30B15/20—Controlling or regulating
    • C30B15/22—Stabilisation or shape controlling of the molten zone near the pulled crystal; Controlling the section of the crystal
    • C30B15/28—Stabilisation or shape controlling of the molten zone near the pulled crystal; Controlling the section of the crystal using weight changes of the crystal or the melt, e.g. flotation methods
    • 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
    • Y10T117/1032—Seed pulling

Definitions

  • My invention relates to the method of pulling rodshaped crystals of semiconductor material from a molten mass of the material contained in a crucible, and has for its main object to reliably provide for a constant cross section of the crystalline rod being produced.
  • the adjustment and maintenance of a given rod diameter during the pulling operation is effected by continuously determining the weight (W) and the length (L) of the rod being pulled and hence the weight-to-length differential quotient (dW/dL) that corresponds to the datum value of the rod diam- -tected with the aid of transducers that furnish respective measuring voltages, and these are compared with each other in an electric network that furnishes an error voltage for controlling the crystal pulling operation.
  • the continuous determination and regulation of the rod diameter by ascertaining the rod weight (W) in dependence upon the pulling length (L) affords performing all necessary measuring operations With the aid of sensing means that need not be located in the immediate vicinity of the liquid-solid phase boundary, thus eliminating the fundamental difficulties of the above-mentioned other methods.
  • the Weight of the rod being pulled increases in proportion to time; consequently it is then only necessary to control the temperature of the melt in dependence upon the continuously measured weight of the rod being pulled.
  • the control of the pulling operation according .to the invent-ion can be effected also by varying the pulling speed.
  • the method at constant crystal pulling speed and to vary the temperature of the melt.
  • the preferably electric measuring magnitude or signal voltage resulting from the change in weight of the rod is employed by means of suitable transmitting devices for controlling the temperature of the melt in the crucible.
  • suitable transmitting devices for controlling the temperature of the melt in the crucible.
  • a synchronous electric motor may be employed, or also a motor equipped with a centrifugal-type speed regulator so as to operate the pulling device at a constant driving speed.
  • the crystal pulling speed is to be varied in an analogous manner under control by the measuring magnitude or signal voltage resulting from the changes in weight of the crystal.
  • strain gauges are any other suitable deformationor force-responsive sensors and transducers, for example piezoelectric transducers.
  • the in crease in crystal weight can also be determined indirectly by continuously measuring the reduction in total weight of the melt-containing crucible.
  • the change in electric resistance resulting from the change in crystal Weight is preferably utilized by connecting the weight-sensing resistor in a bridge network or other comparator network together with a continuously varying reference resistor so that the corresponding voltage drops are opposed to each other and jointly furnish a difference voltage which, since only very small values of this voltage are effective, is indicative of the above-mentioned differential quotient:
  • the occurring differential enror voltage is then employed, preferably upon amplification in an electronic amplifier, for controlling the temperature of the melt in the crucible or for controlling the crystal pulling speed.
  • the control of the crystal pulling operation according to the invention can be effected by varying the pulling speed under control by the differential error voltage resulting from the comparison of the weightresponsive current or voltage with a reference current or voltage varying in dependence upon the length of the crystal being pulled and hence in accordance with the pulling travel.
  • FIG. 1 shows schematically and in section a crystal pulling apparatus operating in accordance with the invention.
  • FIG. 2 is a horizontal cross section through a tubular 1 pulling structure and strain gauges that form part of the apparatus according to FIG. 1.
  • FIG. 3 is a schematic diagram of a temperature regulating circuit applicable in conjunction with the apparatus according to FIGS. 1 and 2.
  • FIG. 4 shows schematically an electric drive for the pulling structure of apparatus otherwise as shown in FIG. 1, but in con-junction with an electric control system for operation at constant temperature of the melt and variable crystal pulling speed.
  • FIGS. 5, 6 and 7 show three different modifications of regulating circuits applicable in lieu of the regulating circuit according to FIG. 3, in conjunction with apparatus as shown in FIG. 1.
  • an evacuated processing vessel 10 'contains a crucible 1 with molten semiconductor material 2 such as silicon, germanium, indium antimonide or any other semiconductor substance suitable for the production of mono-crystals in the above-described manner.
  • the top portion of the processing vessel 10 has a central neck 5 with a cylindrical seal 6 traversed by a pulling structure 9 in form of a cylindrical and tubular rod.
  • the rod-shaped crystal is fastened by means of a clamping device 4 to the bottom portion 8 of the tubular structure 9.
  • the electric leads 11 and 12 of the strain gauges 7 extend upwardly through the interior of the tubular structure 9 to the outside of the processing vessel, the bottom of the tubular structure 9 being hermetically sealed for preserving the vacuum in the vessel during pulling operation, it being understood that it is preferable to have the vessel continuously connected to a vacuum pump and also to provide for opening the vessel before commencing and after terminating the crystal pulling operation.
  • the gauge strips are protected in tube portion 8 from being heated by radiation from the melt 2.
  • cooled heat-shielding members may be added if desired, or a coolant may be supplied to the gauge strips throtigh the interior of the tubular pulling structure 9.
  • FIG. 1 schematically shown in FIG. 1 is a resistance heater
  • the heater 21 is connected in series with an adjustable rhe-ostat 22 and through an amplifier 23 to the output terminals 33, 34 of the bridge network shown in FIG. 3.
  • This circuit diagram relates to operation at constant pulling speed and hence uniform upward travel of the tubular pulling structure 9 during steady-state operation.
  • the variable resistance of the strain gauges 7 is denoted by R
  • This resistance varying in dependence upon the increasing Weight of the crystal, is compared in the bridge network with a resistance R1 which varies continuously in proportion to the pulling speed and consequently at a constant rate of change.
  • the differential signalvoltage issuing from the above-described bridge circuit is used for correspondingly controlling the pulling speed.
  • FIG. 4 One way of doing this is schematically shown in FIG. 4.
  • the tubular pulling structure 9 is displaced upwardly by pinch rollers 39 and 40 driven from the armature 41 of a motor which has a main field winding 42 and a speed-controlling field winding 43.
  • Winding 43 is excited through a control rheostat 44 whose tap is displaced by a solenoid 45 in the output diagonal of a direct-current bridge network essentially corresponding to the one described above with reference to FIG. 3.
  • Another way of practicing the invention relating to operation at constant crystal pulling speed, is to use the weight-responsive measuring current for charging a capacitor, periodically discharging the capacitor, and comparing the resulting capacitor discharge voltage with a controlled reference voltage having a constant rate of change in accordance with the constant pulling speed. The resulting differential error voltage is then available for controlling the temperature of the melt.
  • the modified regulating network shown in FIG. 5, operates in this manner.
  • terminals 11 and 12 according to FIG. 5 are to be connected to the leads 11 and 12 according to FIG. 1, the output terminals 33 and 34 according to FIG. 5 being identical with those designated by 33 and 34 in FIG. ll.
  • a capacitor C is continuously charged by current whose magnitude is controlled by the strain gauges 7 and consequently is determined by the varying weight of the crystal r-od being pulled at constant speed.
  • the capacitor C is periodically discharged by actuation of a switch S, preferably an electronic switch operating in given intervals of time.
  • the capacitor discharge produces a voltage drop U along a resistor R4.
  • This voltage drop is compared with a controllaible voltage U which, aside from the internal resistance of the voltage source, is equal to the voltage drop U which it produces across a resistor R6.
  • the voltage difference AU: U U U U appears across a resistor R5 and between the output terminals 33, 34 and thus is employed for regulating the crystal pulling operation for constancy of the rod diameter.
  • the measuring current varying in dependence upon the crystal weight, is passed through an inductance coil D and the reactive voltage U occurring along the coil is impressed between the output terminals 33 and 34 for controlling the crystal pulling operation.
  • the regulating network according ,to FIG. 7 corre- may be effected, for example, by providing the resistor R1 with a slide contact as shown sponds in principle to that described above with reference to FIG. 5, except that the reference voltage U is not produced 'with the aid of voltage from an auxiliary generator but is derived from the current 1: (L) that is a function of the rod length and hencecontrolled by the abovementioned resistor R1 (FIG. 4).
  • voltage U is compared with the voltage drop U; of a resistor R7 connected between the terminals 11 and 12 and consequently dependent upon the weight-responsive current 1: (G).
  • the voltage diiference appears at a resistor R9 and is impressed across the terminals 33 and 34. This difference voltage is employed for controlling the pulling operation in the above-described manner.
  • Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in a crucible comprising a processing vessel;
  • heater means in operative proximity with said crucible for heating the melt at a substantially constant temperature
  • crystal pulling means mounted in said vessel above said crucible for substantially vertical movement, said crystal pulling means comprising a substantially vertically displaceable member, driving means in operative proximity with said member for moving said member in a substantially vertical direction and crystal holder means on said member for seeding and pulling a crystal rod upwardly out of the melt when said member is moved upwardly;
  • circuit means including variable resistance means having a resistance-varying arm mechanically coupled to the driving means of said crystal pulling means for providing an electrical signal having a magnitude indicative of the length of said crystal rod;
  • electrical comparator means including said strain gage means and said circuit means for comparing the electrical signals corresponding to the weight and the length of the crystal rod to produce an electric control signal proportional to the differential quotient of the rate of change of weight to the rate of change of length of said crystal rod;
  • control means connected to said electrical comparator means and coupled to the driving means of said crystal pulling means for controlling the pulling speed by the electric control signal to maintain the difierential quotient constant thereby to maintain the diameter of the rod-shaped crystal constant.
  • Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in a cruicible comprising a processing vessel;
  • crystal pulling means mounted in said vessel above said This length-responsive crucible for substantially vertical movement, said crystal pulling means comprising a substantially vertically displaceable member, driving means in operative proximity with said member for moving said member in a substantially vertical direction and crystal holder means on said member for seeding and pulling a crystal rod upwardly out of the melt when said member is moved upwardly;
  • piezoelectric force gage means aflixed to the member of said crystal pulling means for providing an electrical signal having a magnitude indicative of the weight of said crystal rod;
  • circuit means including variable resistance means havin g a resistance-varying arm mechanically coupled to the driving means of said crystal pulling means for providing an electrical signal having a magnitude indicative of the length of said crystal rod;
  • electrical comparator means including said piezoelectric force gage means and said circuit means for comparing the electrical signals corresponding to the weight and the length of the crystal rod to produce an electric control signal proportional to the diiferential quotient of the rate of change of weight to the rate of change of length of said crystal rod;
  • control means connected to said electrical comparator means and coupled to 'the driving means of said crystal pulling means 'for controlling the pulling speed by the electric control signal to maintain the differential quotient constant thereby to maintain the diameter of the rod-shaped crystal constant.
  • Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in a crucible comprising crystal pulling means mounted in said vessel above said crucible for substantially vertical movement, said crystal pulling means comprising a substantially vertically displaceable elongated tube extending from a sealed lower end in said processing vessel through said vessel to an open upper end outside said vessel, driving means in operative proximity with said tube for moving said tube in a substantially vertical direction and crystal holder means on said tube for seeding and pulling :a crystal rod upwardly out of the melt when said tube is moved upwardly;
  • resistance strain gage means afiixed to the inside of the tube of said crystal pulling means near the lower end thereof for providing an electrical signal having a magnitude indicative of the weight of said crystal rod;
  • circuit means including variable resistance means having a resistance-varying arm mechanically coupled to the driving means of said crystal pulling means for providing an electrical signal having a magnitude indicative of the length of said crystal rod;
  • electrical comparator means including said resistance strain gage means and said circuit means for comparing the electrical signals corresponding to the weight and the length of the crystal rod to produce an electric control signal proportional to the diiferentional quotient of the rate of change of weight to the rate of change of length of said crystal rod;
  • control means connected to said electrical comparator means and coupled to the driving means of said crystal pulling means for controlling the pulling speed by the electric control signal to maintain the 7 differential quotient constant thereby to maintain 2,992,311 7/ 1961 Keller 23 -301 the diameter of the rod-shaped crystal constant. 3,046,379 7/ 1962 Keller et a1 23-301 References Cited by the Examiner DAVID L. RECK, Primary Examiner.

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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)
US327659A 1962-12-07 1963-12-03 Apparatus for pulling rod-shaped crystals of semiconductor material from a melt in acrucible Expired - Lifetime US3259467A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES82753A DE1245317B (de) 1962-12-07 1962-12-07 Verfahren zum Herstellen von stabfoermigem, kristallinem Halbleitermaterial durch Ziehen aus einer im Tiegel befindlichen Schmelze

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US3259467A true US3259467A (en) 1966-07-05

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US (1) US3259467A (cs)
CH (1) CH426739A (cs)
DE (1) DE1245317B (cs)
GB (1) GB1008300A (cs)
NL (1) NL300759A (cs)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3934983A (en) * 1972-09-08 1976-01-27 National Research Development Corporation Weighing cell apparatus for diameter control of a rotatable growing crystal
JPS51126853A (en) * 1975-04-28 1976-11-05 B Ii Ii:Kk A diameter deviation detecting method at a crystal hoister
US4073355A (en) * 1975-04-14 1978-02-14 Prolizenz Ag. Crucible
FR2622189A1 (fr) * 1987-10-23 1989-04-28 Leybold Ag Procede et dispositif pour le frittage et la densification d'ebauches ceramiques
US5656058A (en) * 1994-11-14 1997-08-12 Lucent Technologies Inc. Apparatus for inserting a core fiber into a partially molten cladding glass to form an optical fiber preform
US5763838A (en) * 1995-03-27 1998-06-09 Ohkura Electric Co., Ltd. Apparatus for weighing a grown crystal

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2908004A (en) * 1957-05-10 1959-10-06 Levinson John Temperature control for crystal pulling
US2913561A (en) * 1958-04-22 1959-11-17 Siemens Ag Processing semiconductor rods
US2992311A (en) * 1960-09-28 1961-07-11 Siemens Ag Method and apparatus for floatingzone melting of semiconductor rods
US3046379A (en) * 1959-09-11 1962-07-24 Siemens Ag Method and apparatus for zone melting of semiconductor material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2908004A (en) * 1957-05-10 1959-10-06 Levinson John Temperature control for crystal pulling
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
US2992311A (en) * 1960-09-28 1961-07-11 Siemens Ag Method and apparatus for floatingzone melting of semiconductor rods

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3934983A (en) * 1972-09-08 1976-01-27 National Research Development Corporation Weighing cell apparatus for diameter control of a rotatable growing crystal
US4073355A (en) * 1975-04-14 1978-02-14 Prolizenz Ag. Crucible
JPS51126853A (en) * 1975-04-28 1976-11-05 B Ii Ii:Kk A diameter deviation detecting method at a crystal hoister
FR2622189A1 (fr) * 1987-10-23 1989-04-28 Leybold Ag Procede et dispositif pour le frittage et la densification d'ebauches ceramiques
US5656058A (en) * 1994-11-14 1997-08-12 Lucent Technologies Inc. Apparatus for inserting a core fiber into a partially molten cladding glass to form an optical fiber preform
US5763838A (en) * 1995-03-27 1998-06-09 Ohkura Electric Co., Ltd. Apparatus for weighing a grown crystal

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Publication number Publication date
DE1245317B (de) 1967-07-27
CH426739A (de) 1966-12-31
GB1008300A (en) 1965-10-27
NL300759A (cs)

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