US3865554A

US3865554A - Pressure-and temperature-controlled apparatus for large-scale production of crystals by the czochralski technique

Info

Publication number: US3865554A
Application number: US183169A
Authority: US
Inventors: Joseph F Wenckus; Roger A Castonguay; Bernard C Hanfly; Francis J Mallahan
Original assignee: Arthur D Little Inc
Current assignee: Arthur D Little Inc
Priority date: 1971-09-23
Filing date: 1971-09-23
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11
Also published as: FR2153247A1; JPS4839377A; FR2153247B3; DE2240788A1; GB1392749A

Abstract

Furnace assembly providing a working volume the pressure in which may range from 10 5 torr to 135 atmospheres. Controlled temperatures up to 3,000*C are attainable. A crystal-pulling rod and a crucible-supporting rod extend into the furnace. The crystal-pulling rod is rotated and driven translationally through an extended excursion in a slow crystal-pulling mode and relatively fast positioning mode; while the crucible support rod is rotated and driven translationally through a relatively short excursion in a crucible positioning mode. The main furnace housing is lifted up and swung away to permit ready access to the crucible holding zone for interchange of rf coils and crucible holders as well as for easy safe removal of large crystals suspended from the pulling rod. Means are provided continuously to indicate the precise position of the crystal-pulling rod, to monitor the operation within the furnace by TV, and to control the operations within the furnace from a remote location.

Description

Unite States Patent [191 Wenckus et al.

[ Feb. 11, 1975 1 PRESSURE-AND TEMPERATURE-CONTROLLED APPARATUS FOR LARGE-SCALE PRODUCTION OF CRYSTALS BY THE CZOCHRALSKI TECHNIQUE [75] Inventors: Joseph F. Wenckus, Needham;

Roger A. Castonguay, Salem; Bernard C. Hanfly, Chestnut Hill; Francis J. Mallahan, Woburn, all of Mass.

[73] Assignee: Arthur D. Little, Inc., Cambridge,

Mass.

[22] Filed: Sept. 23, 1971 21 Appl. No.: 183,169

[52] US. Cl. 23/273 SP, 23/301 SP [51] Int. Cl B01j 17/18 [58] Field of Search 23/273 SP, 301 SP [56] References Cited UNITED STATES PATENTS 3,002,320 10/1961 Theuerer 23/273 3,337,303 8/1967 Lorenzini 23/273 3,353,914 11/1967 Pickar, Jr 23/273 3,372,003 3/1968 Yamase 23/273 3,493,770 2/1970 Dessauer et a1. 23/273 3,501,406 3/1970 Kappelmeyer et a1. 23/301 SP l/l97l 3/1972 Dohcrty et al 4. 23/273 3,650,701 Forrat 23/273 [57] ABSTRACT Furnace assembly providing a working volume the pressure in which may range from 10 torr to 135 atmospheres. Controlled temperatures up to 3,000C are attainable. A crystal-pulling rod and a cruciblesupporting rod extend into the furnace. The crystalpulling rod is rotated and driven translationally through an extended excursion in a slow crystalpulling mode and relatively fast positioning mode; while the crucible support rod is rotated and driven translationally through a relatively short excursion in a crucible positioning mode. The main furnace housing is lifted up and swung away to permit ready access to the crucible holding zone for interchange of rf coils and crucible holders as well as for easy safe removal of large crystals suspended from the pulling rod. Means are provided continuously to indicate the precise position of the crystal-pulling rod, to monitor the operation within the furnace by TV, and to control the operations within the furnace from a remote location.

12 Claims, 23 Drawing Figures PMEFJTED 1 SHEET O20F 18 //vVE/V7'0/?$ Roger A. Costonguuy Bernard C. Henley Francis J. Mollohon v Joseph F. Wenckus /i""" a 7 l( Fig. 2

PATENTED 75 SHEET Cu 0F 18 //V|/E/VTOR.S

Roger A. Costonguuy Bernard C. Honley Froncis.J. Mulluhon Hyv Joseph F. Wenckus Attorney PMENTEUFEBI 11% 3 865,554

SHEET DSUF 18 lA/VEA/TORS Roger A. Castongucy Bernard C. Henley v Francis J. Molluhan Flg. 5 y Joseph F. Wenckus fiw'c/ ATTOW PATEHTEDFEBI H 3,865,554 SHEET 07 0F 18 //VVE/V7'0/?5 Flg. 7 Roger A. Costonguuy Bernard C. Henley Francis J. Mollahon 5y Joseph E wenckus Attor nzy PIR'IIENTEUFEBI 1 I975 SHEET 080F123 Fig. IO

m'EmEu Em 1 I975 3; 865,554 sum as ur 18 //V VENTOl-TS Roger A Custonguoy Bernard C. Henley Francis J. Mollahun Joseph E Wenckus Pmmnin 3,865,554

SHEEI 1UUF18 I/VVE/VTORS Roger A. Ccstonguoy Bernard C. Honley Francis J. Mullchcln Joseph F wenckus Attorney sum 110F 18 PATENTED FEB '1 I975 z 2 ul -W a .n Z a l 2 m A a MUI I INVENTORS R A. Custonquoy B rd C. Hcml e y Francis J. Mollohdn Joseph F. Wonckus I Zflorney PATENTEDFEBI 1 I375 SHEET 13UF 18 Roger A Cosfo Bernard C. Hanl Francis J Mallahan BY Joseph F. Wenkus PATENTEU 1 3, 865,554

' SHEET 150F153 M VEA/TORS Roger A Casfonguuy Bernard C. Henley Francis J. Mollahan Joseph F. Wenckus PIIIEIIIIII 1 I915 3,865,554

SHEET 170F 18 REVERSIBLE ELECTRO I MAGNETIC COUNTER 41e TRANSLA-,

TIONAL DRIVING MECHANISM 0.0. I o. c. 333:}, MOTOR MOTOR 417 AC. SUPPLY Hg. 21

AC' II INPUT l 423 422 PROPORTIONAL EST E MAGNETIC 4 TEMPERATURE REACTOR AMPLIFIER CONTROL SYSTEM 1 VOLTS INDUCTION SIGNAL HEATING 7 POWER 42I SUPPLY RADIAMATIC PYROMETER PYRoMETER INVENTO/RS Lad/ Tforney PMEHIEB EB 3,865,554

SHEET 18UF18 76 55 0c MOTOR CQNTROL I f T 43| AC E;\

75 1 5 AC 69 68 5| 1 l 222 74 DC I MOTOR CO'NTROL AC 432 H I DC MOTOR CONTROL I D c T CLUTCH AC X POWER l 9 433 SUPPLY DC \4 MOTOR 3o CONTROL T t I /A/VEA/T0/?S AC Roger A. Costonguuy Bernard C. Hunley Francis J. Mullohun By Joseph F Wenckus PRESSURE-AND TEMPERATURE-CONTROLLED APPARATUS FOR LARGE-SCALE PRODUCTION OF CRYSTALS BY THE CZOCHRALSKI TECHNIQUE This invention relates to an apparatus for growing crystals and more particularly to an apparatus for growing crystals on a large scale by the Czochralski tech nique under controlled atmospheric pressures from torr to 135 atmospheres and at temperatures up to 3,000C.

An apparatus suitable for growing many different types of crystals by the Czochralski technique is required to be able to furnish many different controlled conditions. For example, the growing of crystals of a III-V intermetallic compound may require that a very high pressure be maintained around the growing crystal area to control the vaporization of a volatile component such as arsenic or phosphorus in forming an intermetallic arsenide or phosphide. In other crystal growing processes it may be necessary to supply a moderate to high vacuum. In all cases, however, the working zone within the apparatus must be evacuatable to permit control of the zone atmosphere, whether it is pressurized or evacuated during crystal growth. Such a crystal growing apparatus should be capable of growing crystals of oxides, salts, metals, elemental and intermetallic compound semiconductors including the phosphides, arsenides, tellurides, selenides and sulfides and any other inorganic element, compound or mixtures thereof.

With the ever-increasing demand for single crystal raw stock for making semi-conductor devices, lightemitting diodes, etc., there has arisen the need for a crystal growing apparatus which is safe, reliable and easy to operate for the production of crystals on a large, commercial scale. One of the most widely accepted techniques for forming single crystals is the vertical pulling or Czochralski technique in which a seed crystal is contacted with the surface of a molten reservoir of the material to be formed into a crystal and then gradually pulled upwardly with rotation.

In a copending application Ser. No. 46,096 filed June I5, 1970, in our names and assigned to the same assignee as the present application and now U.S. Pat. No. 3,639,7 l 8, we have described and claimed a multipurpose furnace for experimental purposes for growing crystals by either the Czochralski, Bridgman- Stockbarger, or floating-zone techniques; for forming intermetallic compounds within controlled atmospheres such as by the methods described in U.S. Pat. No. 3,704,093 and Ser. No. 169,315 filed in the names of Wilson P. Menashi, Joseph F. Wenckus and Roger A. Castonguay; and for forming doped crystals of uniform composition. All of the above-identified applications have been assigned to the same assignee as the present case. Inasmuch as the furnace of Ser. No. 46.096 as a versatile research tool must provide for a wide variety of operational conditions, it is not suitable for growing large-scale crystals by a single technique on a commercial basis. In addition to providing for a wide range of operational pressures and temperatures, a crystal growing furance suitable for growing large crystals on a commercial basis should provide easy access for the installation of various sizes and types of crucibles and for the removal of large crystals, fail-safe operational features and complete remote control. The

crystal growing apparatus of this invention, hereinafter eferred to as a furnace meets all of these requirements as will be evident from the following detailed description.

It is therefore a primary object of this invention to provide a crystal growing furnace for producing crystals on a commercial scale by the Czochralski technique which may be used over a pressure range from as low as I0 torr to as high as atmospheres and at temperatures up to 3,000C. It is another object of this invention to provide apparatus of the character described which offers rapid. easy and safe access to the working zone, which makes possible the growing of a crystal over a wide size range, and which permits the use of a wide variation in crucible sizes and configurations to supply the molten crystalforming material. It is yet another object of this invention to provide such apparatus which is suitable for operation by remote control and remote observation, and which has built into it safety features which make the apparatus reliable to use under any extreme high vacuum or pressure and temperatures desired. It is yet another object of this invention to provide such an apparatus which permits rapid height adjustments of the upper or crystalpulling rod before, during, and after the crystal growing operation and which provides means for continous monitoring of the position of the crystal-pulling rod. Other objects of the invention will in part be obvious and will in part be apparent hereinafter.

The invention accordingly comprises the features of construction, combinations of elements, and arrange ments of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which FIG. 1 is a perspective view of the apparatus of this invention showing the furnace assembly in operational condition, the power supply and the operational console;

FIG. 2 is a front view of the furnace assembly of FIG. I illustrating the main furnace housing raised and swung away for access to the working zone;

FIGS. 3, 4 and 5 are side, top and end views, respectively, of the crystal-pulling rod driving mechanism;

FIG. 6 is a top plan view of the furnace assembly;

FIG. 7 is a side elevational view of the furnace assem- FIGS. 8 and 9 are cross sections through the furnace chamber lift support structure taken along lines 8-8 and 9-9, respectively, of FIG. 7;

FIG. 10 is a side elevational view of the crucible support mechansim, vacuum system, pressure-control system and hydraulic system of the furnace assembly FIG. 11 is a front elevational view of the furnace;

FIG. 12 is a fragmentary detail of a warning device mounted on the furance housing to prevent opening of the furnace when it is pressurized;

FIG. 13 is a front elevational view of the crucible support mechanism, vacuum system, pressure-control system and hydraulic system of the furnace assembly;

FIG. I4 is a vertical cross section of the furnace showing one window in cross section and one embodiment of the crucible holder;

Claims

1. A PRESSURE- AND TEMPERATURE-CONTROLLED APPARATUS ADAPTED FOR GROWING CRYSTALS BY THE CZOCHRALSKI TECHNIQUE, COMPRISING IN COMBINATION A. PRESSURE-TIGHT FURNACE MEANS PROVIDING AN ENCLOSURE DIFINING THEREIN A WORKING VOLUME THE ATMOSPHERE OF WHICH MAY BE VARIED WITH RESPECT TO TEMPERATURE AND TO PRESSURE FROM A VACUUM TO AT LEAST 100 ATMOSPHERES, SAID FURNACE MEANS BEING FORMED OF A MAIN CYLINDRICAL FURNACE HOUSING OF ESSENTIALLY CONSTANT DIAMETER THROUGHOUT HAVING A TOP SECTION AND BOTTOM FLANGE MEANS AND A FURNACE BASE MEMBER HAVING THE SAME INSIDE DIAMETER AS SAID MAIN FURNACE HOUSING AND BEING SEALABLE WITH SAID MAIN FURMACE HOUSING THROUGH MATING FLANGE MEANS TO LIMIT SAID ATMOSPHERE ESSENTIALLY TO SAID VOLUME; B. FURNACE SEALING MEANS ENGAGEABLE WITH SAID MATING FLANGE MEANS AND COMPRISING TWO SEMICIRCULAR, INTERNALLY GROOVED MEMBERS AND BOLT MEANS ADAPTED TO LOCK SAID GROOVED MEMBERS IN ENGAGED POSITION AROUND SAID MATING FLANGE MEANS; C. CRYSTAL-PULLING ROD MEANS EXTENDING FROM EXTERNAL OF SAID MAIN FURNACE HOUSING INTO SAID VOLUME AND MOVABLE THEREIN IN BOTH ROTATIONAL AND TRANSLATIONAL MODES D. CRYSTAL-PULLING ROD BEARING AND SEALING ASSEMBLY MEANS LOCATED IN SAID TOP SECTION OF SAID MAIN FURNACE HOUSING AND PROVIDING THE SOLE SEALING MEANS BETWEEN SAID CRYSTAL-PULLING ROD MEANS AND SAID PRESSURE-TIGHT FURNACE MEANS; E. ROTATIONAL AND TRANSLATION CRYSTAL-PULLING ROD DRIVING MEANS LOCATED EXTERNAL OF SAID PRESSURE-TIGHT FURNACE MEANS AND RIGIDLY MOUNTED ON SAID MAIN FURNACE HOUSING, SAID TRANSLATIONAL DRIVING MEANS INCLUDING MEANS TO SELECTIVELY DRIVE SAID RODS IN A SLOW CRYSTAL-GROWING MODE OR IN A RIPID-POSITIONING MODE;

2. An apparatus according to claim 1 wherein said pressure-tight furnace means includes external cooling means in the form of coils adapted to circulate a fluid coolant.

3. An apparatus according to claim 1 wherein said pressure-tight furnace means has associated therewith a self-resetting pressure-relief valve and a solenoid-actuated relief valve.

4. An apparatus according to claim 1 wherein said pressure-tight furnace means includes audible pressure warning means associated with and actuated by said furnace sealing means.

5. An apparatus according to claim 1 wherein said crystal-pulling rod means incorporates fluid channels therein adapted to circulate a fluid coolant therethrough.

6. An apparatus according to claim 1 wherein said crucible-support rod means provides a passage for thermocouple lead wires extending into said crucible holding means.

7. An apparatus according to claim 1 wherein said main furnace housing support and lifting means comprises a hydraulically operated lifting shaft attached to said main furnace housing and means to prevent the rotation of said shaft until it reaches said predetermined height.

8. An apparatus according to claim 1 wherein said crucible holding means comprises a crucible holder terminating at its lower end in a neck member adapted for attachment through a collar member to said crucible-support rod, and outer shielding means surrounding said crucible holder, said crucible holder and said outer shielding means being readily interchangeable, thereby providing means to hold crucibles of varying sizes and configurations.

9. An apparatus according to claim 1 wherein said heating means comprise rf coil means surrounding said crucible holding means.

10. An apparatus according to claim 1 wherein said heating means comprise resistance heater means surrounding said crucible holding means.

11. An apparatus according to claim 10 wherein said resistance heater means comprises a graphite resistance heater, a copper pad, means to circulate a liquid coolant in said copper pad, and means to support said heater means.

12. An apparatus according to claim 1 wherein said heating means has leads terminating in connecting means engageable with connecting means positioned within said furnace base member, whereby said heating means may be readily interchanged to accommodate different sized crucibles.