[go: up one dir, main page]

US3929557A - Periodically and alternately accelerating and decelerating rotation rate of a feed crystal - Google Patents

Periodically and alternately accelerating and decelerating rotation rate of a feed crystal Download PDF

Info

Publication number
US3929557A
US3929557A US369035A US36903573A US3929557A US 3929557 A US3929557 A US 3929557A US 369035 A US369035 A US 369035A US 36903573 A US36903573 A US 36903573A US 3929557 A US3929557 A US 3929557A
Authority
US
United States
Prior art keywords
rate
crystal
seed crystal
rotation
growing
Prior art date
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
Application number
US369035A
Inventor
John W Goodrum
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United States Department of the Air Force
Original Assignee
United States Department of the Air Force
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by United States Department of the Air Force filed Critical United States Department of the Air Force
Priority to US369035A priority Critical patent/US3929557A/en
Application granted granted Critical
Publication of US3929557A publication Critical patent/US3929557A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • C30B15/30—Mechanisms for rotating or moving either the melt or the crystal

Definitions

  • ABSTRACT A method for growing a rod-like crystalline boule by placing a rotating seed crystal in contact with the surfaces of a molton solution of crystal growing materials, then withdrawing the seed crystal while simultaneously lowering the temperature of the solution and subjecting the rotating seed crystal to a periodic acceleration and deceleration of its rotation rate.
  • This invention relates generally to a method for growing single crystal materials. More particularly, this invention concerns itself with an improved technique for growing crystalline boules which includes imparting l a particular type of rotation to a seed crystal relative to a melt of crystalline growing material in such a manner that a crystalline boule of improved characteristics is produced.
  • the lack of homogeneity throughout the molten solution that comes in contact with the seed crystal has spawned the growth of boules of relatively poor quality although of sufficient size.
  • the grown crystals do not exhibit a uniform stoichiometric compositional content throughout the crystal structure resulting in the formation of defects in the crystal body.
  • the problem is especially acute when growing mixed single crystals having two or more chemical compounding constituents.
  • rod-like crystalline boules of good quality and large size can be grown by a novel technique that imparts a periodic acceleration and a deceleration to the rotation rate of the rotating seed crystal utilized in the conventional crystal pulling methods for growing crys- O talline boules.
  • the rotation of the seed crystal is accelerated and then decelerated at a constant rate.
  • the acceleration cycle of seed rotation will vary depending upon the viscosity of the solution with thicker solutions requiring a lower rotation rate.
  • the application of the acceleration affect promotes an even distribution of the crystal growing materials contained in the molten mixture. This reduces the problem of solution inhomogeneity near the growing crystal.
  • the diffusion boundary is periodically shifted and the conditions favoring constitutional supercooling in the solution are drastically reduced.
  • the primary object of this invention is to provide an improved method for growing high quality, large size, rodlike crystalline boules.
  • Another object of this invention is to impart a periodic rate of acceleration and deceleration to the rotation of the seed crystal utilized in the crystal pulling method for growing crystal boules.
  • Still another object of this invention is to provide an improved method for overcoming the problem of solution inhomogeneity that occurs when pulling crystals from a molten bath of crystal growing material.
  • FIGURE represents a schematic illustration of an apparatus suitable for use in carrying out the method of the invention.
  • rod-like crystalline boules of relatively large size and excellent quality are grown by a technique which involves the step of periodically accelerating and decelerating the rotation rate of a rotating seed crystal at a constant rate for a predetermined period of time.
  • the well known crystal pulling technique for growing single crystals includes the step of rotating a seed crystal as it is slowly withdrawn from a molten bath of crystal growing material. This method is often referred to as the Czochralski method and, in general, involves the steps of placing a rotating seed crystal in contact with a molten solution of a crystal growing material. The seed crystal is slowly withdrawn from the molten compound.
  • Freezing occurs at the interface resulting in the formation of a rod-like crystalline boule on the rotating seed crystal as it is withdrawn.
  • the seed crystal is rotated at a specific rate over a predetermined time depending upon the particular material being grown, melt temperature and other well known growth variables.
  • FIGURE shows, in schematic form, a conventional Czochralski type vertical pull crystal growing apparatus.
  • the apparatus is suitable for carrying out the practice of this invention and comprises, in general, a crystal growing furnace, 10, a motor 12 for rotating and pulling a shaft 14 which in turn is connected to a seed crystal 16.
  • the acceleration and deceleration of the rotating crystal is accomplished by means of a conventional motor speed controller 18 and a variable slow speed motor.
  • the elements 18 and 20 are each connected to a suitable source of electric power, not shown.
  • the furnace also includes a viewing port 22, a heating element 24 for melting the crystal growing compound, and a water-cooled chamber 26 for cooling the growing crystal 36 as it is withdrawn from the molten crystal growing material 28.
  • the melt 28 is positioned within a crucible 30 located on top of a crucible support 32.
  • a temperature sensor 34 is positioned adjacent to the crucible in order to control the temperature of the melt 28.
  • Suitable top and bottom covers are shown respectively at 38 and 40 in order to provide a closed and controlled atmosphere for the growing process.
  • the novel procedure for growing crystals in accordance with the modified crystal pulling technique of this invention initially involves growing C-axis oriented needle-like crystals for use as a seed. These are grown by cooling a solution of crystal growing material in the presence of platinum wire which is attached to a seed rod.
  • a seed crystal 16 is placed on the end of a shaft or seed rod 14 and dipped into the surface of a molten solution of crystal growing material 28 which has been previously heated by coils 24 to a temperature above the melting point of the crystal growing solution.
  • the melt 28 is then slowly cooled at a programmed rate while the seed rod is slowly withdrawn and rotated at the predetermined rate.
  • the rotation rate is periodically accelerated and then decelerated at a constant rate for a fixed period of time.
  • the acceleration rate varies with the viscosity of the melt 28. Solutions having a viscosity of 40 poise requires a rotating cycle ofO rpm to 50 rpm to 0 rpm with a cycle time of 1 minute. The rotating cycle of acceleration and deacceleration is maintained at the predetermined rate until crystal growth is completed. For solutions having a viscosity greater than 40 poise, the maximum rpm must be less than 50 while for solutions with a viscosity of less than 40 poise, the maximum rpm must be greater than 50.
  • a mixture of electronic grade germanuim dioxide with a reagent grade alkali oxide, such as lithium, sodium or potassium, as the solvent were dry mixed for 15 hours and then placed in a platnuim crucible in a Czochalski type apparatus such as shown in the drawing.
  • the mix contained 90.36 molar percent G 0 with Li O; 92.30 molar percent G 0 with Na O and 93.96 molar percent with K 0.
  • the mixture with Li2O as the solvent was heated to l,200C and held at that temperature for one hour for addition mixing.
  • a seed crystal was placed in contact with the surface of the melt and rotated while the melt temperature was slowly lowered at a programmed rate of 2C per hour.
  • the seed crystal rotation was periodically accelerated and decelerated at a constant rate of from zero rpm to 30 rpm to 0 rpm for an acceleration cycle period of 1 minute. This periodic change in the rate of rotation was maintained until a crystal of sufficient length was grown. All crystallization occurred on the seed as the temperature of the bath was lowered between approximately l,050C to 975C. As the solution was about to freeze at its eutectic point, the crystal was pulled out of the melt.
  • the crystal was then cooled at about 200C per hour to room temperature.
  • a pull rate of 0.50 mm per hour permitted the growth of tetragonal germanium dioxide crystals of about 3 mm times 10 mm in size.
  • the crystals were grown on the 001 plane and were single as shown by its Laue pattern following seed orientation.
  • the method of this invention is clearly applicable to other materials which can be formed into rod-like single crystals or where a seed crystal can be rotated as it comes in contact with a molten solution of crystal growing material. It is to be understood, also, that the method of this invention may be altered or modified in any manner which suggests itself to those skilled in the art and that all such modification as fall within the scope of the appended claims is intended to be included herein.
  • a system for growing single crystalline boules which comprises the steps of placing a seed crystal in contact with the surface of a molten solution of crystal growing material, lowering the temperature of the molten solution at a programmed rate to a temperature sufficient to effect the formation of a rod-like crystalline boule on said seed crystal while simultaneously rotating and withdrawing said seed crystal during said lowering of said temperature, and cooling said formed crystalline boules to room temperature, the improvement which comprises periodically altering the rotation rate of said rotating seed crystal by alternately accelerating and decelerating said rate of rotation at a constant rate for a predetermined period of time.
  • rate of rotation must be greater than 50 revolutions per minute when the viscosity of said molten solution is less than 40 poise.
  • a method in accordance with claim 1 wherein said decelerating from 30 to revolutions per minute at a temperature of said molten solution is lowered from constant rate for a period of one minute and said rotatl,200C to 975C at a programmed rate of 2C per ing seed crystal is withdrawn from said molten solution hour; said rate of rotation is periodically altered by 5 at a rate of 0.50 mm per hour. accelerating from 0 to 30 revolutions per minute and

Landscapes

  • 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)

Abstract

A method for growing a rod-like crystalline boule by placing a rotating seed crystal in contact with the surfaces of a molton solution of crystal growing materials, then withdrawing the seed crystal while simultaneously lowering the temperature of the solution and subjecting the rotating seed crystal to a periodic acceleration and deceleration of its rotation rate.

Description

United States Patent Goodrum Dec. 30, 1975 [54] PERIODICALLY AND ALTERNATELY 2,962,363 11/1960 Martin 23/301 ACCELERATING AND DECELERATING 3/ Gobal 52 38 3, 7 3/1 Yamase l ROTATION RATE OF A FEED CRYSTAL 3,490,877 1 1970 Bollen et al... 23 301 [75] Inventor: John W. Goodrum, Atlanta, Ga. 3,650,702 3 1972 Swets 23 301 [73] Assignee: The United States of America as represented by the Secretary of the Air Force, Washington, DC.
Filed: June 11, 1973 Appl. No.: 369,035
US. Cl l56/6l7; 23/301 SP; 23/273 SP Int. Cl. B01J 17/18 Field of Search 23/301 SP, 273 SP References Cited UNITED STATES PATENTS 6/1959 Rosi 23/301 9/1959 Horn 23/301 Primary ExaminerN0rman Yudkoff Assistant Examiner-D. Sanders Attorney, Agent, or Firm-Joseph E. Rusz; William J. OBrien [57] ABSTRACT A method for growing a rod-like crystalline boule by placing a rotating seed crystal in contact with the surfaces of a molton solution of crystal growing materials, then withdrawing the seed crystal while simultaneously lowering the temperature of the solution and subjecting the rotating seed crystal to a periodic acceleration and deceleration of its rotation rate.
5 Claims, 1 Drawing Figure PERIODICALLY ALTERNATELY /ACCELERATING AND DECELARATING ROTATION RATE /4 58 PERIODICALLY AND ALTERNATELY ACCELERATING AND DECELERATING ROTATION RATE OF A FEED CRYSTAL BACKGROUND OF THE INVENTION This invention relates generally to a method for growing single crystal materials. More particularly, this invention concerns itself with an improved technique for growing crystalline boules which includes imparting l a particular type of rotation to a seed crystal relative to a melt of crystalline growing material in such a manner that a crystalline boule of improved characteristics is produced.
Recent advances in the utilization of single crystals for various electronic applications has generated considerable research in the development of improved techniques for growing crystals having improved physical properties. A problem has arisen, however, in connection with the ultimate evaluation of the crystals physical characteristics. If a proper evaluation is to be made, then a crystal boule of excellent quality and of sufficient size for measurements must be produced. A number of methods are known for forming single crystals. The so-called Czochralski method, or crystal-pulling technique, has proven to be quite successful in producing rod-like crystal boules of considerable length. In this method, a seed crystal is placed on a rod which is lowered into a crucible containing a melt of crystal growing material. The seed crystal is placed in contact with the molten material and then slowly pulled from the melt. Since freezing occurs at the interface, growth occurs on the seed as it is withdrawn, resulting in the formation of a rod-like crystal boule. Another method, similar to Czochralski, is the Kryopoulos Technique. In this method, the seed, or a cooled rod, remains in contact with the molten crystal growing material and slow cooling causes crystallization to occur from the seed or rod into the melt. In these methods, the seed rod or the crucible is sometimes rotated as a modification of the basic technique. Also, these methods can be used under ambient conditions, vacuum or pressures up to atmospheres as still further modifications. All have been employed at one time or another in attempts at providing large size crystalline boules of good quality.
However, the lack of homogeneity throughout the molten solution that comes in contact with the seed crystal has spawned the growth of boules of relatively poor quality although of sufficient size. The grown crystals do not exhibit a uniform stoichiometric compositional content throughout the crystal structure resulting in the formation of defects in the crystal body. The problem is especially acute when growing mixed single crystals having two or more chemical compounding constituents.
With this invention, however, it has been found that the problem of melt homogeneity that occurs when growing crystals with the well known crystal-pulling techniques can be drastically minimized by a modification that involves the periodic acceleration and deceleration of the rotation rate of the seed crystal at predetermined rates. The implementation of the modification of this invention provides crystal boules rod-like in character and of considerable length. The crystals show markedly better quality than crystals grown in accordance with previously known techniques.
SUMMARY OF THE INVENTION In accordance with this invention, it has been found that rod-like crystalline boules of good quality and large size can be grown by a novel technique that imparts a periodic acceleration and a deceleration to the rotation rate of the rotating seed crystal utilized in the conventional crystal pulling methods for growing crys- O talline boules. The rotation of the seed crystal is accelerated and then decelerated at a constant rate. However, the acceleration cycle of seed rotation will vary depending upon the viscosity of the solution with thicker solutions requiring a lower rotation rate. The application of the acceleration affect promotes an even distribution of the crystal growing materials contained in the molten mixture. This reduces the problem of solution inhomogeneity near the growing crystal. The diffusion boundary is periodically shifted and the conditions favoring constitutional supercooling in the solution are drastically reduced. These two effects normally promote poor quality in growing crystals, but with the acceleration and deceleration concept of this invention, the two undesirable effects are overcome.
Accordingly, the primary object of this invention is to provide an improved method for growing high quality, large size, rodlike crystalline boules.
Another object of this invention is to impart a periodic rate of acceleration and deceleration to the rotation of the seed crystal utilized in the crystal pulling method for growing crystal boules.
Still another object of this invention is to provide an improved method for overcoming the problem of solution inhomogeneity that occurs when pulling crystals from a molten bath of crystal growing material.
Still other objects and advantages of the present invention will become apparent upon consideration of the following detailed description thereof when taken in conjunction with the accompanying drawing.
DESCRIPTION OF THE DRAWINGS In the Drawings:
The FIGURE represents a schematic illustration of an apparatus suitable for use in carrying out the method of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the method of this invention, rod-like crystalline boules of relatively large size and excellent quality are grown by a technique which involves the step of periodically accelerating and decelerating the rotation rate of a rotating seed crystal at a constant rate for a predetermined period of time. The well known crystal pulling technique for growing single crystals includes the step of rotating a seed crystal as it is slowly withdrawn from a molten bath of crystal growing material. This method is often referred to as the Czochralski method and, in general, involves the steps of placing a rotating seed crystal in contact with a molten solution of a crystal growing material. The seed crystal is slowly withdrawn from the molten compound. Freezing occurs at the interface resulting in the formation of a rod-like crystalline boule on the rotating seed crystal as it is withdrawn. The seed crystal is rotated at a specific rate over a predetermined time depending upon the particular material being grown, melt temperature and other well known growth variables.
In this invention, however, it has been unexpectdely found that improved crystalline boules, both as to quality and size can be grown if the rotation rate of the said crystal is periodically accelerated and then decelerated. The periods of accelerating and decelerating the rotation rate occurs at a constant rate over a predetermined time. The acceleration cycle is varied only with respect to the viscosity of the solution used for growing the crystal. For a solution with a viscosity of 40 poise, the seed crystal acceleration cycle is: rpm to 50 rpm to 0 rpm with a cycle time of 1 minute. For solutions with a viscosity greater than 40 poise, the maximum rpm must be less than 50. For solutions with a viscosity of less than 40 poise, the maximum rpm must be greater than 50.
Attention is now directed to the FIGURE in the drawing which shows, in schematic form, a conventional Czochralski type vertical pull crystal growing apparatus. The apparatus is suitable for carrying out the practice of this invention and comprises, in general, a crystal growing furnace, 10, a motor 12 for rotating and pulling a shaft 14 which in turn is connected to a seed crystal 16. The acceleration and deceleration of the rotating crystal is accomplished by means of a conventional motor speed controller 18 and a variable slow speed motor. The elements 18 and 20 are each connected to a suitable source of electric power, not shown. The furnace also includes a viewing port 22, a heating element 24 for melting the crystal growing compound, and a water-cooled chamber 26 for cooling the growing crystal 36 as it is withdrawn from the molten crystal growing material 28. The melt 28 is positioned within a crucible 30 located on top of a crucible support 32. A temperature sensor 34 is positioned adjacent to the crucible in order to control the temperature of the melt 28. Suitable top and bottom covers are shown respectively at 38 and 40 in order to provide a closed and controlled atmosphere for the growing process.
The novel procedure for growing crystals in accordance with the modified crystal pulling technique of this invention initially involves growing C-axis oriented needle-like crystals for use as a seed. These are grown by cooling a solution of crystal growing material in the presence of platinum wire which is attached to a seed rod. In carrying out the practice of the invention, a seed crystal 16 is placed on the end of a shaft or seed rod 14 and dipped into the surface of a molten solution of crystal growing material 28 which has been previously heated by coils 24 to a temperature above the melting point of the crystal growing solution. The melt 28 is then slowly cooled at a programmed rate while the seed rod is slowly withdrawn and rotated at the predetermined rate. The rotation rate is periodically accelerated and then decelerated at a constant rate for a fixed period of time. The acceleration rate varies with the viscosity of the melt 28. Solutions having a viscosity of 40 poise requires a rotating cycle ofO rpm to 50 rpm to 0 rpm with a cycle time of 1 minute. The rotating cycle of acceleration and deacceleration is maintained at the predetermined rate until crystal growth is completed. For solutions having a viscosity greater than 40 poise, the maximum rpm must be less than 50 while for solutions with a viscosity of less than 40 poise, the maximum rpm must be greater than 50.
To further illustrate a specific embodiment of the invention reference is made to the following description of the formation of tetragonal single crystals of germanuim dioxide. A mixture of electronic grade germanuim dioxide with a reagent grade alkali oxide, such as lithium, sodium or potassium, as the solvent were dry mixed for 15 hours and then placed in a platnuim crucible in a Czochalski type apparatus such as shown in the drawing. The mix contained 90.36 molar percent G 0 with Li O; 92.30 molar percent G 0 with Na O and 93.96 molar percent with K 0.
' The mixture with Li2O as the solvent was heated to l,200C and held at that temperature for one hour for addition mixing. A seed crystal was placed in contact with the surface of the melt and rotated while the melt temperature was slowly lowered at a programmed rate of 2C per hour. The seed crystal rotation was periodically accelerated and decelerated at a constant rate of from zero rpm to 30 rpm to 0 rpm for an acceleration cycle period of 1 minute. This periodic change in the rate of rotation was maintained until a crystal of sufficient length was grown. All crystallization occurred on the seed as the temperature of the bath was lowered between approximately l,050C to 975C. As the solution was about to freeze at its eutectic point, the crystal was pulled out of the melt. The crystal was then cooled at about 200C per hour to room temperature. A pull rate of 0.50 mm per hour permitted the growth of tetragonal germanium dioxide crystals of about 3 mm times 10 mm in size. The crystals were grown on the 001 plane and were single as shown by its Laue pattern following seed orientation.
The method of this invention is clearly applicable to other materials which can be formed into rod-like single crystals or where a seed crystal can be rotated as it comes in contact with a molten solution of crystal growing material. It is to be understood, also, that the method of this invention may be altered or modified in any manner which suggests itself to those skilled in the art and that all such modification as fall within the scope of the appended claims is intended to be included herein.
What is claimed is: I
1. In a system for growing single crystalline boules which comprises the steps of placing a seed crystal in contact with the surface of a molten solution of crystal growing material, lowering the temperature of the molten solution at a programmed rate to a temperature sufficient to effect the formation of a rod-like crystalline boule on said seed crystal while simultaneously rotating and withdrawing said seed crystal during said lowering of said temperature, and cooling said formed crystalline boules to room temperature, the improvement which comprises periodically altering the rotation rate of said rotating seed crystal by alternately accelerating and decelerating said rate of rotation at a constant rate for a predetermined period of time.
2. A method in accordance with claim 1 wherein said rate of rotation must be less than 50 revolutions per minute when the viscosity of said molten solution is greater than 40 poise.
3. A method in accordance with claim 1 wherein rate of rotation must be greater than 50 revolutions per minute when the viscosity of said molten solution is less than 40 poise.
4. A method in accordance with claim 1 wherein the rate of rotation of said rotating seed crystal is accelerated from 0 to 50 revolutions per minute and then decelerated from 50 to 0 revolutions per minute at a constant rate for a period of about 1 minute.
5 6 5. A method in accordance with claim 1 wherein said decelerating from 30 to revolutions per minute at a temperature of said molten solution is lowered from constant rate for a period of one minute and said rotatl,200C to 975C at a programmed rate of 2C per ing seed crystal is withdrawn from said molten solution hour; said rate of rotation is periodically altered by 5 at a rate of 0.50 mm per hour. accelerating from 0 to 30 revolutions per minute and

Claims (5)

1. IN A SYSTEM FOR GROWING SINGLE CRYSTALLINE BOULES WHICH COMPRISES THE STEPS OF PLACING A SEED CRYSTAL IN CONTACT WITH THE SURFACE OF A MOLTEN SOLUTION OF CRYSTAL GROWING MATERIAL, LOWERING THE TEMPERATURE OF THE MOLTEN SOLUTION AT A PROGRAMMED RATE TO A TEMPERATURE SUFFICIENT TO EFFECT THE FORMATION OF A ROD-LIKE CRYSTALLINE BOULE ON SAID SEED CRYSTAL WHILE SIMULTANEOUSLY ROTATING AND WITHDRAWING SAID SEED CRYSTAL DURING SAID LOWERING OF SAID TEMPERATURE, AND COOLING SAID FORMED CRYSTALLINE BOULES TO ROOM TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES PERIODICALLY ALTERING THE ROTATION RATE OF SAID ROTATING SEED CRYSTAL BY ALTERNATELY ACCELERATING AND DECELERATING SAID RATE OF ROTATION AT A CONSTANT RATE FOR A PREDETERMINED PERIOD OF TIME.
2. A method in accordance with claim 1 wherein said rate of rotation must be less than 50 revolutions per minute when the viscosity of said molten solution is greater than 40 poise.
3. A method in accordance with claim 1 wherein rate of rotation must be greater than 50 revolutions per minute when the viscosity of said molten solution is less than 40 poise.
4. A method in accordance with claim 1 wherein the rate of rotation of said rotating seed crystal is accelerated from 0 to 50 revolutions per minute and then decelerated from 50 to 0 revolutions per minute at a constant rate for a period of about 1 minute.
5. A method in accordance with claim 1 wherein said temperature of said molten solution is lowered from 1,200*C to 975*C at a programmed rate of 2*C per hour; said rate of rotation is periodically altered by accelerating from 0 to 30 revolutions per minute and decelerating from 30 to 0 revolutions per minute at a constant rate for a period of one minute and said rotating seed crystal is withdrawn from said molten solution at a rate of 0.50 mm per hour.
US369035A 1973-06-11 1973-06-11 Periodically and alternately accelerating and decelerating rotation rate of a feed crystal Expired - Lifetime US3929557A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US369035A US3929557A (en) 1973-06-11 1973-06-11 Periodically and alternately accelerating and decelerating rotation rate of a feed crystal

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US369035A US3929557A (en) 1973-06-11 1973-06-11 Periodically and alternately accelerating and decelerating rotation rate of a feed crystal

Publications (1)

Publication Number Publication Date
US3929557A true US3929557A (en) 1975-12-30

Family

ID=23453800

Family Applications (1)

Application Number Title Priority Date Filing Date
US369035A Expired - Lifetime US3929557A (en) 1973-06-11 1973-06-11 Periodically and alternately accelerating and decelerating rotation rate of a feed crystal

Country Status (1)

Country Link
US (1) US3929557A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040895A (en) * 1975-10-22 1977-08-09 International Business Machines Corporation Control of oxygen in silicon crystals
US4239585A (en) * 1977-12-30 1980-12-16 Wacker-Chemitronic Gesellschaft Fur Elektronik-Grundstoffe Mbh Process for the production of high purity silicon monocrystals having a low oxygen content
US4474641A (en) * 1981-04-29 1984-10-02 U.S. Philips Corporation Method of drawing a silicon rod
US4511428A (en) * 1982-07-09 1985-04-16 International Business Machines Corporation Method of controlling oxygen content and distribution in grown silicon crystals
US4659423A (en) * 1986-04-28 1987-04-21 International Business Machines Corporation Semiconductor crystal growth via variable melt rotation
US4678534A (en) * 1984-06-08 1987-07-07 Sumitomo Electric Industries, Ltd. Method for growing a single crystal
WO1990003952A1 (en) * 1988-10-07 1990-04-19 Crystal Systems, Inc. Method of growing silicon ingots using a rotating melt
US5306387A (en) * 1990-06-21 1994-04-26 Shin-Etsu Handotai Co., Ltd. Method for pulling up semiconductor single crystal
US5359959A (en) * 1990-05-25 1994-11-01 Shin-Etsu Handotai Co., Ltd. Method for pulling up semi-conductor single crystal
US5593498A (en) * 1995-06-09 1997-01-14 Memc Electronic Materials, Inc. Apparatus for rotating a crucible of a crystal pulling machine
US20100024718A1 (en) * 2008-07-31 2010-02-04 Benno Orschel Procedure for in-situ determination of thermal gradients at the crystal growth front

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2889240A (en) * 1956-03-01 1959-06-02 Rca Corp Method and apparatus for growing semi-conductive single crystals from a melt
US2904512A (en) * 1956-07-02 1959-09-15 Gen Electric Growth of uniform composition semiconductor crystals
US2962363A (en) * 1957-07-09 1960-11-29 Pacific Semiconductors Inc Crystal pulling apparatus and method
US3173765A (en) * 1955-03-18 1965-03-16 Itt Method of making crystalline silicon semiconductor material
US3372003A (en) * 1963-07-19 1968-03-05 Shin Nippon Chisso Hiryo Kabus Apparatus and method for producing silicon single crystals for semiconductor
US3490877A (en) * 1965-08-05 1970-01-20 Nl Centrale Organistatie Voor Reverse rotation of crystallization melt
US3650702A (en) * 1970-04-15 1972-03-21 Gen Motors Corp Crystal growth of tetragonal germanium dioxide from a flux

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173765A (en) * 1955-03-18 1965-03-16 Itt Method of making crystalline silicon semiconductor material
US2889240A (en) * 1956-03-01 1959-06-02 Rca Corp Method and apparatus for growing semi-conductive single crystals from a melt
US2904512A (en) * 1956-07-02 1959-09-15 Gen Electric Growth of uniform composition semiconductor crystals
US2962363A (en) * 1957-07-09 1960-11-29 Pacific Semiconductors Inc Crystal pulling apparatus and method
US3372003A (en) * 1963-07-19 1968-03-05 Shin Nippon Chisso Hiryo Kabus Apparatus and method for producing silicon single crystals for semiconductor
US3490877A (en) * 1965-08-05 1970-01-20 Nl Centrale Organistatie Voor Reverse rotation of crystallization melt
US3650702A (en) * 1970-04-15 1972-03-21 Gen Motors Corp Crystal growth of tetragonal germanium dioxide from a flux

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040895A (en) * 1975-10-22 1977-08-09 International Business Machines Corporation Control of oxygen in silicon crystals
US4239585A (en) * 1977-12-30 1980-12-16 Wacker-Chemitronic Gesellschaft Fur Elektronik-Grundstoffe Mbh Process for the production of high purity silicon monocrystals having a low oxygen content
US4474641A (en) * 1981-04-29 1984-10-02 U.S. Philips Corporation Method of drawing a silicon rod
US4511428A (en) * 1982-07-09 1985-04-16 International Business Machines Corporation Method of controlling oxygen content and distribution in grown silicon crystals
US4678534A (en) * 1984-06-08 1987-07-07 Sumitomo Electric Industries, Ltd. Method for growing a single crystal
US4659423A (en) * 1986-04-28 1987-04-21 International Business Machines Corporation Semiconductor crystal growth via variable melt rotation
WO1990003952A1 (en) * 1988-10-07 1990-04-19 Crystal Systems, Inc. Method of growing silicon ingots using a rotating melt
US5359959A (en) * 1990-05-25 1994-11-01 Shin-Etsu Handotai Co., Ltd. Method for pulling up semi-conductor single crystal
US5306387A (en) * 1990-06-21 1994-04-26 Shin-Etsu Handotai Co., Ltd. Method for pulling up semiconductor single crystal
US5593498A (en) * 1995-06-09 1997-01-14 Memc Electronic Materials, Inc. Apparatus for rotating a crucible of a crystal pulling machine
US5766341A (en) * 1995-06-09 1998-06-16 Memc Electric Materials, Inc. Method for rotating a crucible of a crystal pulling machine
US20100024718A1 (en) * 2008-07-31 2010-02-04 Benno Orschel Procedure for in-situ determination of thermal gradients at the crystal growth front
JP2010037191A (en) * 2008-07-31 2010-02-18 Sumco Phoenix Corp Method for growing single crystal silicon ingot and apparatus therefor
US8221545B2 (en) * 2008-07-31 2012-07-17 Sumco Phoenix Corporation Procedure for in-situ determination of thermal gradients at the crystal growth front
US8673075B2 (en) 2008-07-31 2014-03-18 Sumco Phoenix Corporation Procedure for in-situ determination of thermal gradients at the crystal growth front

Similar Documents

Publication Publication Date Title
US4040895A (en) Control of oxygen in silicon crystals
US3929557A (en) Periodically and alternately accelerating and decelerating rotation rate of a feed crystal
CA1155735A (en) Method for making silicon rods
CN101405440B (en) Process for producing nitride single-crystal and apparatus therefor
US3173765A (en) Method of making crystalline silicon semiconductor material
EP0000720B1 (en) Process for producing single crystal of yttrium-iron garnet solid solution
US4303465A (en) Method of growing monocrystals of corundum from a melt
US3401023A (en) Crystal melt-growth process wherein the melt surface is covered with an inert liquid
US5788764A (en) KTP solid solution single crystals and process for the production thereof
US3261722A (en) Process for preparing semiconductor ingots within a depression
EP0104741A1 (en) Process for growing crystalline material
US3689242A (en) Method of preparing electrically and optically active vitreous and polycrystalline materials
CN1155742C (en) Melt Growth Method of Sodium Borophosphate Crystal
US3043671A (en) Zinc oxide crystal growth method
RU2753671C1 (en) METHOD FOR PRODUCING Bi4Ge3O12 BISMUTH GERMANATE BY CASTING
JPS6158898A (en) Manufacture of bismuth germanate crystal
JPH0253397B2 (en)
RU1431391C (en) Process of growing monocrystals of cadmium telluride
JP3613424B2 (en) Manufacturing method of oxide superconductor
JPH07115861B2 (en) Method for manufacturing single crystal growing material
JP2977297B2 (en) Crystal manufacturing method
SU1319641A2 (en) Method of obtaining monocrystalls of gadolinium-gallium sarnet
JPS6065794A (en) Production of high-quality gallium arsenide single crystal
JPH0751477B2 (en) Single crystal growth method
JPH01138199A (en) Lead-tin-tellurium based semiconductor single crystal