US3454368A - Apparatus for crucible-free floating zone melting of crystalline rods - Google Patents

Apparatus for crucible-free floating zone melting of crystalline rods Download PDF

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Publication number
US3454368A
US3454368A US554805A US3454368DA US3454368A US 3454368 A US3454368 A US 3454368A US 554805 A US554805 A US 554805A US 3454368D A US3454368D A US 3454368DA US 3454368 A US3454368 A US 3454368A
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US
United States
Prior art keywords
rod
melting
clutch
seed
zone
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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
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US554805A
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English (en)
Inventor
Wolfgang Keller
Gunther Berger
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Siemens AG
Siemens Corp
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Siemens Corp
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Publication date
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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
    • C30B13/32—Mechanisms for moving either the charge or the heater
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10S117/91—Downward pulling
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1004—Apparatus with means for measuring, testing, or sensing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10T117/10—Apparatus
    • Y10T117/1024—Apparatus for crystallization from liquid or supercritical state
    • Y10T117/1032—Seed pulling
    • Y10T117/1072—Seed pulling including details of means providing product movement [e.g., shaft guides, servo means]

Definitions

  • the lower member has two vertically aligned fractionally engageable clutch plate members, the lower member being downwardly displaceable for uncoupling the one holder from the drive shaft before a molten zone is produced in the rod by a heating device and, after the molten zone is produced in the rod, the upper member is displaceable downwardly by gravity force so as to frictionally engage the lower member.
  • Our invention relates to crystalline rods for cruciblefree floating zone melting of crystalline rods.
  • Such apparatus comprises an evacuated melting chamber or a melting chamber filled with protective gas in which the rod is located in a vertical position and is secured, for example at its upper end, in a holder which is in turn mounted on a rotary shaft.
  • the rod is surrounded by a heating device such .as a flatly wound induction coil for example, whose windings are disposed in a plane perpendicular to the axis of the rod and supplied with high-frequency alternating current.
  • a heating device such .as a flatly wound induction coil for example, whose windings are disposed in a plane perpendicular to the axis of the rod and supplied with high-frequency alternating current.
  • a monocrystalline seed secured in a holder is fused to the lower end of the crystalline rod with the aid of the heating device.
  • the holder for the seed is mounted on the end of a shaft which is displaceable in the axial direction thereof.
  • the holders of the rod and the seed, respectively are set in rotation. Simultaneously, relative motion is'effected between the induction heating coil and the rod so that the melting zone produced in the rod is displaced from the junction of the seed and rod upwardly along the rod.
  • the rod i.e. the shafts with the holders gripping the rod, or the induction heating coil can be moved in a vertical direction. Purification of the rod is accordingly achieved in this manner.
  • the recrystallized rod growing at the monocrystalline seed from the melt of the melting zone possesses a very extensive monocrystalline structure.
  • the heating power of the melting coil is reduced and the relative motion between the melting coil and the rod' is regulated so that an incandescent or glow zone is passed through the rod and so that the melting coil is again located at the level of the junction location of the seed and rod after termination of the relative motion between the coil and rod. Thereafter, the melting zone is subjected to the full heating power output of the coil and the seed is melted through.
  • a further specific object of our invention is to provide apparatus by means of which the melting of the seed is immediately determinable so that rod and seed can be placed in rotation instantaneously, whereby a uniformly circular cross section of the rod recrystallizing from the melting zone can be achieved.
  • the apparatus of the invention for crucible-free zone melting of a crystalline rod such as of semiconductor material, for example, comprises a pair of end-supporting holders for the rod, at least one of the holders being axially displaceable and rotatably connected to a rotary drive shaft, means for heating the rod to produce a molten zone therein, the rod and said heating means being relatively displaceable so as to pass the molten zone through the rod along the axis thereof, and clutch means located between said one holder and said rotary drive shaft, said clutch means comprising a pair of engageable clutch members, at least one of said clutch members being axially displaceable for disengaging said one holder from said drive shaft.
  • FIG. 1 is a perspective view, partly in cross section and partly broken away, of the apparatus constructed in accordance with our invention wherein the coupling elements are disc-shaped;
  • FIG. 2 is a similar view of a second embodiment of the apparatus of FIG. 1 wherein the coupling elements are conical or funnel-shaped.
  • FIG. 1 an apparatus wherein a crystalline rod 3 of silicon for example, is vertically mounted in a melting chamber 1 filled with protective gas or evacuated, and is surrounded by a heating device, for example a stationary flat meltproducing induction coil 13.
  • the upper end of the rod 3 is secured in a holder 2 mounted at the end of a shaft 4.
  • the shaft 4 can be displaced in the axial direction thereof, that is, in a vertically upward and downward direction.
  • a monocrystalline seed 5 which is secured in a holder 6.
  • the seed 5 is fused by the heat produced from the melting coil 13 to the lower end of the rod 3 during the first pass of the melting zone along the rod 3.
  • the holder 6 is mounted in the center of the upper flat surface of the upper member 7 of a coupling or clutch consisting of two disc-shaped members.
  • the upper disc-shaped half 7 of the clutch can consist of chrome-nickel-steel alloy (stainless steel), for example.
  • chrome-nickel-steel alloy stainless steel
  • the second disc-shaped half 10 of the clutch or coupling is located beneath the coupling half 7 and is mounted at the end of a drive shaft 9.
  • the secondcoupling half 10 can consist of ceramic, for example.
  • Three conical pins 12 are mounted on the upper fiat surface of the lower disc-shaped element 10 of the coupling, and are uniformly distributed along an imaginary circle aligned with the aforementioned groove 8 formed in the upper disc-shaped element 7 of the coupling.
  • the pins 12 are thus located at the corners of an equilateral triangle and can engage in the groove 8 of the upper disc-shaped element 7 of the coupling.
  • the lengths of the conical pins 12 are selected so that they are advantageously somewhat longer than the depth of the groove 8.
  • Two of the pins 12 consist of electrically conductive material, such as chromenickel-steel alloy for example, and are connected electrically with two slip rings 11 mounted on the shaft 9.
  • the shaft 9 is displaced axially downwardly so that the coupling halves 7 and 10 are spaced from one another from 0.5 to 2 mm. To ensure the fact that secure coupling or clutch engagement will take place, this spacing is so selected that, even after the shaft 9 is downwardly displaced, the points of the conical pins 12 remain inserted in the groove 8 Without contacting the walls thereof, i.e. during disengagement of the clutch members. Thereafter, the bused seed 5 is remelted with the aid of the melting coil 13. Since the seed 5 is actually not rigidly clamped at the lower end thereof as seen in FIG. 1, it remains free of thermal stresses during the heating operation.
  • the coupling half 7 drops down onto the coupling half 10 and the conical pins 12 become inserted into the groove 8 of the coupling half 7. Since the length of the pins 12 is greater than the depth of the groove 8, the coupling half 7 does not lie directly on the coupling half 10. Nevertheless, because the pins 12 are uniformly distributed circumferentially on the lower coupling half 10, e.g. the pins 12 are located at the points of an imaginary equilateral triangle, the connection between the coupling halves 7 and 10 thus formed is free of any play.
  • the circuit of an electric control device or an electric signal device which, as shown schematically in FIG. 1, for example is connected through brushes with the slip rings 11 and with the two electrically conductive pins 12, can be closed, so as to actuate a relay 16 for example to 4 energize a motor or motors setting both shafts 4 and 9 instantaneously into rotation.
  • the dropping of the coupling half 7 can also be observed through a viewing window 14 in the melting chamber by servicing personnel for the apparatus, whereby the rotation of the shafts 4 and 9 can then be effected or instituted by manual means.
  • a crystalline rod 23 which can consist of silicon for example, is vertically mounted in an evacuated melting chamber 21 or a melting chamber filled with protective gas, and the rod 23 is surrounded by a stationary flat melt-producing induction coil 33, The upper end of the rod 23 is secured in a holder, not shown in FIG. 2, which is in turn mounted at the end of a shaft, which is also not shown in FIG. 2.
  • the non-illustrated shaft can, if desired, be displaced in the axial direction of the rod 23.
  • a monocrystalline seed 25 which is secured in a holder 26 and which is fused to the lower end of the rod during the first pass of the melting zone which is effected by heating with the melt-producing induction coil 33.
  • the holder 26 is mounted at the upper female or hollow member 27 of a friction type coupling or clutch formed with conical or funnel-shaped friction surfaces.
  • the lower coupling half or male member 30 is secured to a drive shaft 21, also displaceable in the axial direction of the rod 23.
  • the drive shaft 29 of apparatus embodiment shown in FIG. 2 is displaced axially downwardly so that the coupling halves 27 and 30 are spaced from one another, the spacing being selected in order to ensure a secure coupling or clutch engagement by providing for a portion of the coupling half 30 to project into the hollow coupling half 27 without engaging any portion of the latter.
  • the feed 25 is melted through.
  • the upper coupling half 27 drops down onto the lower coupling half 30 and effects a connection free of play between the seed crystal 25 and the drive shaft 29.
  • This operation can be observed, for example by servicing personnel through an observation window 34 so they can immediately effect the rotation of the shafts 24 and 29 as the coupling half 27 drops down.
  • the distance through which the coupling half 27 falls can be substantially between 0.5 and 2 mm.
  • zone-melting apparatuses By means of clutches or couplings, such as those of FIGS. 1 and 2, which are releasable by axial movement thereof, zone-melting apparatuses can also be employed wherein the crystalline rod is fixed and the heating device, for example the induction heating coil, can be suitably mounted so that it is displaceable in a vertical direction.
  • the drive shaft with which the coupling or clutch has to effect a connection must be movable in the axially downward direction of the rod as viewed in the figures so that the upper coupling half can drop at the moment the seed is melted through.
  • Apparatus for crucible-free zone melting of a crystalline rod comprising a pair of substantially vertically aligned holders for respectively supporting the rod substantially vertically at the ends thereof, at least one of said holders being displaceable in the axial direction of the rod and being rotatably connected to a rotary drive shaft, means for heating the rod to produce a molten zone therein, the rod and said heating means being relatively displaceable so as to pass the molten zone through the rod along the axis thereof, and clutch means located between said one holder and said rotary drive shaft, said clutch means comprising a pair of frictionally engageable clutch members located one above the other, the lower one of said clutch members being displaceable downwardly in the axial direction of the rod for uncoupling said one holder from said drive shaft prior to producing the molten zone in the rod, and the upper one of said clutch members, after the molten zone is produced in the rod, being displaceable by force of gravity to a lower position wherein it frictionally engages said lower one of said clutch members
  • Apparatus according to claim 1 including electrical conductive means on said clutch means adapted, to conduct an electrical current upon frictional engagement of said clutch members, and electrical control means connected to said electrical conductive means for rotating said rod end holders in response to clutching engagement of said clutch members.
  • Apparatus according to claim 2 including electrical indicating means connected to said electrical conductive means for indicating clutching engagement of both of said clutch members.
  • said clutch members are disc-shaped, each having a face opposing a face of the other, one of said clutch members being formed with an annular groove on said face thereof, and the other of said clutch members having at least three conical pins extending from said respective face thereof, said pins having a length greater than the depth of said annular groove, said pins being substantially equally spaced circumferentially on said face of said other clutch member in alignment with said annular groove of said one clutch member, whereby said pins are adapted to be inserted into said annular groove, said pins, in disengaged condition of said clutch members, extending into said annular groove though spaced from the walls of said groove, said heating means effecting a release of one of said clutch members by producing the melting zone in the rod.
  • Apparatus for crucible-free zone melting of a crystalline rod comprising a pair of holders for respectively supporting the rod at the ends thereof, at least one of said holders being displaceable in the axial direction of the rod and being rotatably connected to a rotary drive shaft, means for heating the rod to produce a molten zone therein, the rod and said heating means being relatively displaceable so as to pass the molten zone through the rod along the axis thereof, and clutch means located between said one holder and said rotary drive shaft, said clutch means comprising a pair of engageable clutch members,
  • said clutch members being displaceable in the axial direction of the rod for uncoupling said one holder from said drive shaft
  • said clutch members being :disc-shaped, each having a face opposing a face of the other, one of said clutch members being formed of electrically conductive material and with an annular groove on said face thereof, and the other of said clutch members being nonconductive and having at least three conical pins, of which at least two are electrically conductive, extending from said respective face thereof, said pins having a length greater than the depth of said annular groove and being substantially equally spaced circumferentially on said face of said other clutch member in alignment with said annular groove of said one clutch member, whereby said pins are adapted to be inserted into said annular groove, said pins being disposed initially so as to extend within said groove but out of eletcrical and frictional engagement with the walls of said groove, said heating means effecting a release of one of said clutch members by uncoupling said one holder to cause completion of an electrical circuit through said pins.
  • Apparatus according to claim 6, including an electric drive motor for rotating one of said rod holders about said substantially vertical axis, said electric drive motor being electrically connected to said electrically conductive pins and being actuable for rotating said one rod holder when said electrically conductive pins are in engagement with the walls of the groove formed in said clutch member of electrically conductive material.

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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)
  • Sampling And Sample Adjustment (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US554805A 1965-06-04 1966-06-02 Apparatus for crucible-free floating zone melting of crystalline rods Expired - Lifetime US3454368A (en)

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Application Number Priority Date Filing Date Title
DES0097473 1965-06-04

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US3454368A true US3454368A (en) 1969-07-08

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US (1) US3454368A (enrdf_load_stackoverflow)
BE (1) BE681815A (enrdf_load_stackoverflow)
CH (1) CH432475A (enrdf_load_stackoverflow)
DE (1) DE1519872A1 (enrdf_load_stackoverflow)
GB (1) GB1126104A (enrdf_load_stackoverflow)
NL (1) NL6607745A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217565A (en) * 1991-11-13 1993-06-08 Wisconsin Alumni Research Foundation Contactless heater floating zone refining and crystal growth
CN107366017A (zh) * 2017-09-04 2017-11-21 青海鑫诺光电科技有限公司 一种单晶硅收尾设备及其使用方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2743200A (en) * 1954-05-27 1956-04-24 Bell Telephone Labor Inc Method of forming junctions in silicon
US2870309A (en) * 1957-06-11 1959-01-20 Emil R Capita Zone purification device
US2989378A (en) * 1956-10-16 1961-06-20 Int Standard Electric Corp Producing silicon of high purity
CA629412A (en) * 1961-10-17 Union Carbide Corporation Method of and apparatus for growing single crystal material
US3046379A (en) * 1959-09-11 1962-07-24 Siemens Ag Method and apparatus for zone melting of semiconductor material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA629412A (en) * 1961-10-17 Union Carbide Corporation Method of and apparatus for growing single crystal material
US2743200A (en) * 1954-05-27 1956-04-24 Bell Telephone Labor Inc Method of forming junctions in silicon
US2989378A (en) * 1956-10-16 1961-06-20 Int Standard Electric Corp Producing silicon of high purity
US2870309A (en) * 1957-06-11 1959-01-20 Emil R Capita Zone purification device
US3046379A (en) * 1959-09-11 1962-07-24 Siemens Ag Method and apparatus for zone melting of semiconductor material

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217565A (en) * 1991-11-13 1993-06-08 Wisconsin Alumni Research Foundation Contactless heater floating zone refining and crystal growth
CN107366017A (zh) * 2017-09-04 2017-11-21 青海鑫诺光电科技有限公司 一种单晶硅收尾设备及其使用方法

Also Published As

Publication number Publication date
NL6607745A (enrdf_load_stackoverflow) 1966-12-05
BE681815A (enrdf_load_stackoverflow) 1966-11-30
GB1126104A (en) 1968-09-05
CH432475A (de) 1967-03-31
DE1519872B2 (enrdf_load_stackoverflow) 1971-10-21
DE1519872A1 (de) 1969-04-10

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