US3009973A - Device for controlling the zone melting of semiconductor rods - Google Patents

Device for controlling the zone melting of semiconductor rods Download PDF

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US3009973A
US3009973A US831289A US83128959A US3009973A US 3009973 A US3009973 A US 3009973A US 831289 A US831289 A US 831289A US 83128959 A US83128959 A US 83128959A US 3009973 A US3009973 A US 3009973A
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Prior art keywords
rod
holder
zone
melting
torque
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US831289A
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English (en)
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Emeis Reimer
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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
    • 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
    • C30B13/285—Crystal holders, e.g. chucks
    • 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

Definitions

  • FIG.4 DEVICE FOR CONTROLLING THE ZONE MELTING OF SEMICONDUCTOR RODS Nov. 21, 1961 4 Sheets-Sheet 3 Filed Aug. 3, 1959 4
  • My invention relates to devices for controlling or regulating the zone melting of rod-shaped semiconductor material for the production of semiconductor elements to be used in electronic semiconductor devices such as rectifiers, transistors, photodiodes and the like.
  • the semiconductor body of such devices in most cases, consists of germanium, silicon or an intermetallic compound of respective elements from the third and fifth groups of the periodic system, such as indium antimonide or indium arsenide.
  • Large quantities of such materials of extremely high purity are required for'industrial production of the electronic devices.
  • Various producing and fabricating methods have been developed for providing such high-purity-materials.
  • a semiconductor-rod obtained by pulling the material out ofa melt or by any other suitable process, can be purified to the de-' sired degree by subjecting the rod to the so-called zonemelting or zone-pulling method.
  • One way of performing this method is to heat the rod to the melting point within an axially limited zone by means of an induction winding, and to then shift the winding back and forth along the rod, to thus advance the molten zone repeatedly along the entire length of the rod, with the effect of eliminating undesired impurities by shifting them toward the rod ends.
  • the devices used for this purpose are also applicable for converting the material into monocrystalline condition.
  • the semiconductor rod is vertically mounted and firmly secured at one end, whereas the other end is turned about the rod axis when the zone is in melted condition.
  • the crystal seed being used may break off or some other disturbance may be encountered.
  • the rotation is started too late after the melting-through moment, the melted zone may sag and cause spherical thickening of the rod or drip away.
  • the apparatus for controlling or regulating the zone-melting operation Patented Nov. 21, 1961 "ice of the semiconductor rod mounted at both ends in ro tatable holders, is provided with a device which, in re sponse to melting-through conditions, imposes a torque upon one of the two holders, and I provide a switch contact which is controlled by the rotation of the holder caused by such torque.
  • the above-mentioned device is provided with a time-delay member which retards the signal transmission of the switching device a given interval of time.
  • the delay member consists preferably of an oil-damping or dashpot device which delays the rotation of the rod holder.
  • the above-mentioned torque may be produced for example by a spring or by the coaction of an electric-current winding with a permanent magnet. In the latter case the torque-producing device can be readily reset to the starting position simply by reversing the poling of the current winding.
  • the torque-producing device it is preferable to locate the torque-producing device, as well as the switch contact, outside of the high-vacuum or protective-gas filled processing vessel of the zone-pulling app'aratus and to couple the torque-producing device with the movable holder inside the vessel by means of a magnetic coupling.
  • This has the advantage that the amount 3 of material and space to be accommodated within the vessel is not increased and that the novel components to be added to the zone-pulling apparatus in accordance with the invention remain readily accessible. Consequently, any trouble is easily recognizable and can immediately be eliminated. It is particularly preferable to mount the oil-damping member outside of the vacuum chamber.
  • a magnetic coupling for connecting the components located outside of the vessel with the rotatable holder inside the vessel is particularly advantageous because it obviates the need for another seal, such as a flexible gasket, and also because it operates entirely free of friction.
  • the movable holder is preferably provided with a magnetizable armature of magnetically soft iron and is mounted within a cup of non-magnetic metal connected with the vessel, whereas the torque-producing device is mounted outside of the cup and acts upon the armature by means of one or more permanent magnets.
  • a U-shaped bracket is mounted outside of the non-magnetic cup and is connected with the torque-producing device, the bracket being rotatable about the axis of the cup and carrying respective permanent magnets on its two limbs.
  • the rotation angle of the U-shaped bracket is preferably limited by two stops which also serve as electric contacts.
  • FIG. 4 shows the complete apparatus together with a schematic circuit diagram of the associated electric control component;
  • FIG. 5 is a schematic diagram of another embodiment of control circuitry applicable with the apparatus of FIGS. 1 to 3, and
  • FIG. 6 illustrates a signal device.
  • the zone-pulling device comprises a vacuum vessel 1 (FIG. 4), whose top 2 has an opening 2a (FIG. 1) closed by a cup structure 3 of non-magnetic material, preferably of aluminum or other light metal, a sealing gasket '4 being interposed.
  • a shaft 5 is fastened by means of a flange 6 to the top portion of the cup structure and carries two ball bearings 7 and 8 in which the upper holder 9 for the semiconductor rod 34 is journalled.
  • the upper end of the semiconductor rod is fastened in holder 9 by means of set screws 10 of which only one is shown.
  • the sleeveshaped holder 9v carries on its upper end a soft-iron armature 11 (FIGS.
  • bracket 13 is mounted by means of ball bearings 14 "on a vertical pivot shaft 15 co-axially aligned with shaft 5, so that the axis of bracket rotation coincides with the rotation axis of the rod holder 9 and hence with the longitudinal axis of the semiconductor rod 34 to be processed.
  • the pivot shaft 15 carries a hub member 16 with vanes 17 of an oil-damping mechanism. Hub 16 and vanes 17 are located in a cavity within the top portion of the cup structure 3. The cavity is closed by a cover 18.
  • bracket 13 Mounted on the yoke portion of bracket 13 is a permanent magnet 19 which, in cooperation with a current coil 20, imposes a torque upon the bracket 13.
  • Coil 20 is. rigidly joined with the cup structure 3 by two supports 21 which also form pole shoes for the coil 20 (FIGS. 1, 2, 3,).
  • An insulating bar 22 serves as a carrier for two stop contacts 23 which limit the angle of rotation of the bracket 13.
  • Two contact pins 24, in electrically conducting connection with each other, are mounted in the bracket 13 but are insulated therefrom. After the bracket passes through the rotation angle a (FIG. 2), the contact pins 24 abut against the respective stop contact 23, thus performing an electric switching operation for the signalling and control purposes more fully described below.
  • the supply of current to the contact pins is effected free of torque through a flexible conduct-or, such as a thin strip of silver 24a (FIG. 6) coming from terminal means 22a mounted on the insulating bar 22.
  • another contact device which mainly consists of a support 25 (FIG. 3), a fixed contact 26 mounted on the support 25, a movable part 27, and a permanent magnet 28 joined with part 27. Any movement of the permanent magnet is transmitted by means of a pin 30 to the movable contact of the device.
  • the operation of the device is as follows.
  • the semiconductor rod 34 to be processed by zone pulling, for example for purification, is inserted into the two holders 9 and 35 of the zone-pulling device as shown in FIG. 4.
  • the lower holder 35 is connected through gears 37 with a drive motor M for rotating the holder 35 about the longitudinal axis of the rod, but the drive is at first inactive.
  • the operation is started by energizing the current coil 20. Due to the coaction of the magnetic field of coil 20 with that of the permanent magnet 19, the magnet attempts to adjust itself in the longitudinal direction of the coil 20.
  • the bracket 13 with which the magnet 19 is firmly connected is journalled for easy rotation, a rotary movement of the permanent magnet would be possible if the bracket were not arrested by the permanent magnets 12 attracting the armature 11.
  • the magnets 12 retain the bracket 13 as long as the armature 11, firmly joined with the rod holder 9, does not permit a rotation.
  • the heating device namely the inductive heating coil IC of the apparatus, is energized so that a limited zone of the rod becomes heated. As soon as the semiconductor rod in the heated zone becomes melted throughout its entire cross section, the rigid connection between the upper and lower rod holders is eliminated, and the upper holder 9 becomes free to rotate.
  • the contact device is used only for signalling purposes, it suffices if the signal is transmitted without delay; for example when the rotation of the bracket occurs relatively rapidly, the closing of the contact between pin 24 and stop contact 23 may immediately close the, circuit of cell 23a to energize an acoustical or optical signal device 23b (FIG; 6) which calls attention of the attendant to the fact that the zone is completely melted.
  • the attendant can then, after any interval of time as may appear desirable, switch on the advancing travel of the heating coil and, hence of the melting zone, and can also switch on the drive, for rotating the portion of the semiconductor rod located beneath the melting. zone. If desired, the; attendant may also effect a change in the amount of power supply.
  • the above-mentioned closing of the electric contact between members 24 and 23 may also be used for the actuation of relays which then set the individual operations in. motion.
  • the desired time delay may be effected electrically, for example by timing relays.
  • the delay may also be obtained by retarding the rotary motion of the bracket 13 as is the case in the example shown in FIGS. 1 to 3.
  • the upper cavity of the cup structure 3, closed by cover 18, is filled with oil or other liquid in order to impede the motion of the vanes 17.
  • the automatic control system illustrated in FIG. 4 provides for delaying action by the above-described hydraulic device comprising the vanes 17 as well as by an electromagnetic timing relay TR.
  • the control system operates'as follows.
  • Switch 40 closes its normally open contacts 41, 42, 43, 44 and is thereafter held closed by a latch releasable under control by a coil 45 whose circuit includes anormally open stop contact 46 in parallel to the freeze-responsive contacts 26 and 29 described above.
  • start button 40 applies alternating current through contacts.
  • the coil IC now moves slowly upward along the rod to perform the desired zone-melting operation.
  • the operation can be stopped either at will by actuation of the stop button 46 or automatically by the contacts 26, 29 which energize the release coil 45 in response to freezing of the melting zone.
  • the automatic control effected by the contacts 26, 29 will be more fully understood from the following. If due to any disturbance, for example failure of the feed voltage applied to the zone-heating device, the melting zone commences to freeze, the upper rod holder 9 is entrained by the rotary motion of the lower rod holder 35. Since the bracket 13 cannot follow this motion, the armature 11 is forcefully torn out of its magnetic connection with the two permanent magnets 12. The armature now passes out of the range of the angle a and, after about one quarter of one rotation, passes into the range of the permanent magnet 28 of the auxiliary contact device. The magnet 28 now moves radially toward the armature 11 and thereby closes the contacts 26 and 29.
  • the invention afi'ords the possibility of supervising not only the melting-through of the semiconductor rod but also the freezing of the melting zone.
  • the closing of contacts 24, 23 may be caused to reverse the poling of the current coil 20, whereafter the bracket 13 returns in the opposite direction and thereafter closes the other contact pair with the effect of initiating the above-mentioned signalling or controlling operation. If then the rotary motion of the lower rod holder is switched on, the bracket 13 remains in the position last reached, which is also its starting position. This is so because the mechanical connections between the upper and lower rod holders are now virtually interrupted by the intermediate melting zone.
  • FIG. 5 An apparatus comprising the features last described is illustrated in FIG. 5, it being understood that the zonemelting device proper is in accordance with that described above with refcrence to FIGS. 1 to 4.
  • the automatic operation is initiated by actuating a push-button switch 70 which closes its normally open contacts 71 to 74.
  • the contacts 73 and 74 energize the induction heater IC.
  • a control relay R1 picks up because its coil 50 is energized through contacts 71 and 72 from a source of direct current under control by the closed contacts 23a, 24.
  • Relay R1 closes its normally open contacts 51, 52, 53.
  • Contact 51 energizes the torque winding 20 with the polarity indicated by an arrow A.
  • the bracket 13 now rotates in the opposite direction.
  • the relay R1 again picks up, and both relays R1 and R2 remain sealed in.
  • the contacts 63 and 53 being both closed simultaneously, energize the drive motor M for rotating the rod 34 and shifting the induction heater IC along the rod in the same manner as explained above with reference to FIG. 4.
  • the operation is terminated either by actuation of the stop button 77 or by the closing of the freeze-responsive contacts 26, 29 which operate in the manner described above with reference to FIG. 4.
  • a control apparatus responsive to the condition of the rod zone heated by said heater and comprising bearing means in which one of said holders is rotatable about said axis relative to said other holder when the rod zone is melted, torque means operatively coupled with said rotatable holder, and electric switch means having a switch member operatively connected with said rotatable holder for controlling said switch means to operate when said torque means cause rotation of said rotatable holder due to melting-thorugh of said rod zone.
  • Apparatus according to claim 1 comprising a timedelay device connected with said switch means for delaying the operation of said switch means beyond the melting through moment.
  • Apparatus according to claim 1 comprising a hydraulic damper having two relatively movable members and having liquid means for damping the relative motion of said members, one of said damper members being connected with said rotatable holder and the other being fixed.
  • said torque means comprising a ferromagnetic member and an electric winding inductively coupled with each other of which one is fixed and the other is mechanically connected with said rotatable holder, and electric current supply means con-. nected with said winding for energizing it.
  • said torque means comprising a permanent magnet and an electric winding inductively coupled with each other of which one is fixed and the other is mechanically connected with said rotatable holder, a direct-current energizing circuitconnected with said winding, a polarity-reversing switch in said circuit for reversing the sense of the torque produced by said torque means, and limit control means connecting said reversing switch with said rotatable holder for causing said torque means to reverse the rotation of said rotatable holder when said holder reaches a given limit position of rotation.
  • a device for the zone melting of semiconductor rods having a processing vessel sealed when in operation, two coaxially spaced rod-end holders in said vessel, and a zone heater surrounding the holder axis in said vessel and displaceable along said axis, the combination of a control apparatus responsive to the condition of the rod zone heated by said heater and comprising bearing means in which one of said holders is rotatable about said axis relative to said other holder when the rod zone is melted, torque producing means mounted outside said vessel, torque transmitting means inside said vessel connected with said rotatable holder and magnetically coupled with said torque producing means, and electric switch means mounted outside said vessel and having a switch control member connected with said torque producing means for controlling said switch means to operate when said torque producing means are permitted to rotate by said rotatable holder due to melting through of said rod zone.
  • said vessel comprising a cup-shaped housing structure of non-magnetic material disposed in coaxial relation to said rotatable holder, said torque transmitting member having a magnetizable armature located in said cup structure in coaxial relation to said rotatable holder and forming two diametrically opposite pole faces, and said torque producing means having a substantially U-shaped bracket coaxially rotatable relative to said cup structure and straddling said cup structure, and two permanent magnets mounted on the respective legs of said bracket opposite said respective pole faces for magnetically coupling said torque producmg means with said armature.
  • a device comprising stationary stop means engageable by said torque producing means for limiting its angle of rotation, and auxiliary electric switching means mounted outside said vessel and magneti- 'cally responsive to said torque transmitting means when said torque transmitting means, due to excessive rotation of said rotatable holder, passes beyond said limited rotation angle of said torque producing means, whereby said auxiliary switching means are controlled to operate upon occurrence of faulty operation of the zone-melting device.
  • a zone-melting device comprising two stops engageable with said bracket for limiting its angle of rotation, auxiliary switching means for response to faulty operation of the zone melting device, said auxiliary switching means having a switch control member comprising a permanent magnet mounted on said bracket near the pat-h of said armature but at a location beyond said angle of bracket rotation, whereby said permanent magnet becomes magnetically coupled to cause operation of said auxiliary switching means when said armature rotates beyond said limited angle of bracket rotation.
  • a device for the zone melting of semiconductor rods having two coaxially spaced holders for attaching the respective rod ends and having a zone heater surrounding the holder axis and displaceable along said axis, one of said holders having drive means for turning it about said axis during zone melting operation and the other holder being coaxially rotatable relative to said one holder when the rod zone is melted through by said heater, the combination of control apparatus responsive to the condition of said zone and comprising torque means operatively connected with said rotatable holder for subjecting it to torque about said axis, electric switch means having a switch member operatively connected with said rotatable holder for controlling said switch means to operate when said torque means cause rotation of said rotatable holder due to melting through of said rod zone, stop means engageable with said torque means for limiting its angle of rotation, and auxiliary electric switching means responsive to rotation of said rotatable holder beyond said angle of rotation of said torque producing means, whereby said auxiliary switching means are caused to operate when said rotatable holder
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, upwardly-downwardly axially spaced holder members in said vessel, the holder members being adapted to support opposite end portions of said rod, a heating eans, power-operated means for turning a first one of the holder means about the axis of the holders, means for relative longitudinal movement of the heating means lengthwise of the rod, means for rotatably supporting the second one of the holder members for rotation about said axis, means for establishing a magnetic flux in a fixed direction, a magnet means located near said flux, the magnet means being adapted to adjust itself in the flux direction, means operative so that torque applied by said flux is temporarily inoperative to turn the magnet means until the second one of the holder members is made free to turn by melting-through of said rod by said heating means, and signal means operative when the melting-through of the rod permits said torque to turn said magnet means.
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, upwardly-downwardly axially spaced holder members in said vessel, the holder members being adapted to support opposite end portions of said rod, a heating means, power-operated means for turning a first one of the holder members about the axisof the holders, means for relative longitudinal movement of the heating means lengthwiseof the rod, means for rotatably supporting the second one of the holder members for rotation about said axis, means for establishing a magnetic flux in a fixed direction, a magnet means located near said fiux, the magnet means being adapted to adjust itself in the flux direction, means operative so that torque applied by said flux is temporarily inoperative to turn the magnet means until the second one of the holder members is made free to turn by melting-through of said rod by said heating means, and control means operative at a time not before the melting-through of the rod permits said torque to turn the second holder member, said control means being operably connected to automatically
  • control means including a time delay device to delay the automatic initiating of said rotating.
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, coaxial holder members in said vessel, the holder members being adapted to support opposite end portions of said rod, a heating coil in said vessel, poweroperated means for turning a first one of the holder members about the axis of the holders, means for relative longitudinal movement of the heating coil lengthwise of the rod, bearing means for rotatably supporting the second one of the holder members for rotation about said axis, a coil carrying current for establishing a magnetic flux in a fixed direction, a first magnet means located near said flux, current supply means connectable to said coil toenergize it and to thereby initiate the operation of said power-operated means, the first magnet means being adapted to adjust itself in the flux direction, a second magnet means, which is outside of the chamber enclosed by said vessel, a third magnet means in the chamber enclosed by said vessel and mounted upon the second one of the holder members, the second and third magnet means being juxtaposed to act on each other
  • a second magnet means which is outside of the chamber enclosed by said vessel, a third magnet meansin the chamber enclosed by said vessel and mounted upon the second one of the holder members, the second and third magnet means being juxtaposed to act on each other so that the torque applied by said flux is temporarily inoperative to turn the said first magnet means until the second one of the-holder members, and consequently the third magnet means, is made free to turn by meltingthrough of said rod by said coil, and control means operative at a time not before the melting-through of the rod permits said torque to turn the second holder memher, said control means being operably connected to automatically initiate the said turning of the first one of the holder members.
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, upwardly-downwardly axially spaced holder members in said vessel, the holder members being adapted to support opposite endportions of said rod, a
  • heating means power-operated means for turning a first one of the holder members about the axis of the holders, means for relative longitudinal movement of the heating means lengthwise of the rod, means for rotatably supporting the second one of the holder members for rotation about said axis, means for establishing a magnetic flux in a fixed direction, a magnet means located near said .flux, the magnet means being adapted to adjust itself in the flux direction, means operative so that torque applied by said flux is temporarily inoperative to turn the magnet means until the second one of the holder members is made free to turn by meltingthrough of said rod by said heating means, and a device for automatically initiating the rotating of said first holder'member subsequently/to the melting-through, the device comprising means governed according to the angular position of the magnet means, said device including a time delay means to delay the automatic initiating of said rotating.
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, upwardly-downwardly axially spaced holder members in said vessel, the holder members being adapted to support opposite end portions of said rod, a heating means, power-operated meansfor turning a first 10 ing means lengthwise of the rod, meansfor rotatably supporting the second one of the holder members for rotationabout said axis, and an auxiliary device for supervising the accidental freezing of the molten zone due to faulty operation of the heating means, said auxiliary device including control means governed by the rotation of the second holder member with the first f holder member, said rotation being caused by said freezone of the holder members about the axis of the holders,
  • control means for relative longitudinal movement of the heating of the molten zone, said control means comprising a device to stop the operation of the apparatus.
  • An apparatus for zone melting a rod of meltable material comprising a vessel enclosing a zone-melting chamber, coaxial holder members in said vessel, the holder members being adapted to support opposite end portions of said rod, a heating coil in said vessel, power-operated means for turning a first one of the holder members about the axis of the holders, means for relative longitudinal movement of the heating coil lengthwise of the rod, means for rotatably supporting the second one of the holder members for rotation about said axis, a coil carrying current mounted outside the vessel for establishing a magnetic flux in a fixed direction, a first magnet means outside said vessel and located near said flux, means supporting the first magnet means, said -means for supporting being mounted for movement about said axis, current supply means carried by said means for supporting and connectable to said coil to energize it and to thereby initiate the operation of said apparatus, the first magnet means being adapted to adjust itself in the flux direction, so that a torque is applied to the means for supporting the first magnet means, a second magnet means,
  • control means including a time delay device to delay the automatic initiating of said rotating, the device comprising means governed according to the angular position of said magnet means.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Induction Heating (AREA)
  • Arc Welding Control (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
US831289A 1958-08-16 1959-08-03 Device for controlling the zone melting of semiconductor rods Expired - Lifetime US3009973A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES59437A DE1141086B (de) 1958-08-16 1958-08-16 Vorrichtung zur UEberwachung des durchgeschmolzenen Zustandes einer Schmelzzone beim tiegelfreien Zonenschmelzen

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US (1) US3009973A (xx)
BE (1) BE581687A (xx)
CH (1) CH373193A (xx)
DE (1) DE1141086B (xx)
FR (1) FR1232565A (xx)
GB (1) GB907478A (xx)
NL (2) NL240020A (xx)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3211881A (en) * 1962-08-28 1965-10-12 Westinghouse Electric Corp Apparatus for zone heating
US3241924A (en) * 1960-02-05 1966-03-22 Philips Corp Devices for carrying out rotary movements under the action of magnetic forces
US4176002A (en) * 1974-08-21 1979-11-27 Agence Nationale De Valorisation De La Recherche (Anvar) Controlling the melt temperature during zone refining and Czochralski crystal growth by sensing the viscous torque of the melt zone during operation

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2362398A (en) * 1942-08-01 1944-11-07 Ralph R Pittman Thermally responsive device
US2764027A (en) * 1954-04-19 1956-09-25 Otto Walter Thermal fuse
US2870309A (en) * 1957-06-11 1959-01-20 Emil R Capita Zone purification device
US2876147A (en) * 1953-02-14 1959-03-03 Siemens Ag Method of and apparatus for producing semiconductor material
US2898429A (en) * 1957-11-15 1959-08-04 Siemens Ag Crucible-free zone-melting apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2362398A (en) * 1942-08-01 1944-11-07 Ralph R Pittman Thermally responsive device
US2876147A (en) * 1953-02-14 1959-03-03 Siemens Ag Method of and apparatus for producing semiconductor material
US2764027A (en) * 1954-04-19 1956-09-25 Otto Walter Thermal fuse
US2870309A (en) * 1957-06-11 1959-01-20 Emil R Capita Zone purification device
US2898429A (en) * 1957-11-15 1959-08-04 Siemens Ag Crucible-free zone-melting apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3241924A (en) * 1960-02-05 1966-03-22 Philips Corp Devices for carrying out rotary movements under the action of magnetic forces
US3211881A (en) * 1962-08-28 1965-10-12 Westinghouse Electric Corp Apparatus for zone heating
US4176002A (en) * 1974-08-21 1979-11-27 Agence Nationale De Valorisation De La Recherche (Anvar) Controlling the melt temperature during zone refining and Czochralski crystal growth by sensing the viscous torque of the melt zone during operation

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CH373193A (de) 1963-11-15
NL113487C (xx)
FR1232565A (fr) 1960-10-10
BE581687A (xx)
GB907478A (en) 1962-10-03
DE1141086B (de) 1962-12-13
NL240020A (xx)

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