JP2007145620A - Apparatus and method for manufacturing single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a single crystal, in which melting and clogging of a powdery raw material at the tip part of a feeding tube hardly occur when the single crystal is manufactured, and thereby, which can smoothly feed the powdery raw material according to the growth speed and easily manufacture the single crystal having a uniform composition. <P>SOLUTION: The apparatus for manufacturing the single crystal is equipped with a feeding tube 9 for feeding the powdery raw material, crucibles 5, 6 for melting the fed powdery raw material, and a high frequency generation means including a high frequency induction heating coil 3 which is provided so as to surround the crucible 5, 6. At the tip part 9a of the feeding tube 9, a notch 10a is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a single crystal manufacturing apparatus and manufacturing method using the Czochralski method, and more specifically, a single crystal having an improved structure and process for supplying the powder raw material when the powder raw material is melted by high frequency. The present invention relates to a crystal manufacturing apparatus and a method for manufacturing a single crystal.

  Conventionally, single crystal materials have been widely used in various electronic devices. Single crystal materials for electronic devices are required to have a single crystal having a larger size in order to increase productivity. An example of a single crystal manufacturing apparatus that can manufacture such a large size single crystal is disclosed in Patent Document 1 below.

  FIG. 5 is a schematic configuration diagram showing a single crystal manufacturing apparatus described in Patent Document 1. As shown in FIG.

In the single crystal manufacturing apparatus 101, a double crucible 102 is housed inside. The double crucible 102 has a structure in which a cylindrical inner crucible 104 is disposed in a cylindrical outer crucible 103. The inner crucible 104 has a plurality of through holes formed in the side wall. Here, a raw material supply pipe 105 is extended between the outer crucible 103 and the inner crucible 104. The raw material supply pipe 105 is provided for supplying a powder raw material. The powder raw material supplied from the tip of the raw material supply pipe 105 is heated and melted in the double crucible 102. This heating is performed using a high frequency coil 106 disposed around the double crucible 102. On the other hand, a seed crystal 108 attached to the lower end of the holding portion 107 is disposed in the double crucible 102. In manufacturing, a single crystal is grown by melting a powder raw material, immersing the seed crystal 108 in the molten raw material, and pulling up the seed crystal 108.
JP 58-36997 A

  In the conventional single crystal manufacturing apparatus described in Patent Document 1, it is important to keep the composition of the molten raw material in the double crucible 102 constant. Therefore, it is necessary to supply the powder raw material to the lubrication from the tip of the raw material supply pipe 105 according to the growth rate of the single crystal.

  By the way, the powder raw material is heated and melted in the double crucible 102 by the high frequency generated by the high frequency coil 106. This high frequency is preferably applied only to the raw material supplied in the double crucible 102. However, the tip of the raw material supply pipe 105 is extended into the double crucible 102 in order to supply the raw material into the double crucible 102.

  The raw material is in a powder state at the distal end of the raw material supply pipe 105, but when a high frequency is applied, the raw material melts when passing through the raw material supply pipe 105, and the distal end of the raw material supply pipe 105 is clogged. There was a thing.

  In order to avoid such a problem, it is considered that the distal end portion of the raw material supply pipe 105 should be kept away from the crucible 102. However, if the tip of the raw material supply pipe 105 is moved away from the crucible 102, the powder raw material may not be reliably put into the crucible 102 and may be scattered and scattered outside the crucible 102. That is, since it is a powder material, the further away the material supply pipe 105 is from the crucible 102, the higher the possibility that the powder material will not be surely charged into the crucible 102. If it becomes so, the composition of the single crystal to grow will become non-uniform | heterogenous and it will become difficult to obtain the target single crystal reliably.

  In view of the current state of the prior art described above, the present invention provides a single crystal manufacturing apparatus that can reliably supply a powder raw material from a supply pipe to a crucible and can obtain a single crystal having a uniform composition reliably and easily. The object is to provide a method for producing a single crystal.

  A single crystal manufacturing apparatus according to the present invention includes a supply pipe for supplying a powder raw material from a tip portion, a crucible that is supplied with the powder raw material from the tip portion of the supply pipe and contains the supplied powder raw material, and the crucible In the single crystal manufacturing apparatus comprising a high-frequency generating means for heating and melting the powder raw material therein, a notch is provided at the tip of the supply pipe.

  On the specific situation with the single-crystal manufacturing apparatus which concerns on this invention, the said notch is extended in the direction opposite to the front-end | tip part from the front-end | tip part of the said supply pipe | tube.

  In another specific aspect of the apparatus for producing a single crystal according to the present invention, the high-frequency generating means includes a high-frequency coil, the high-frequency coil is disposed so as to surround the crucible, and is provided at a distal end portion of the supply pipe. The supply pipe is close to the crucible so that the cutout is located in a region surrounded by the high-frequency coil.

  A method for producing a single crystal according to the present invention comprises: melting a powder raw material in a crucible; immersing a seed crystal in the molten raw material; and growing the single crystal while pulling up the seed crystal. In the above, the powder raw material is supplied into the crucible from the tip portion of the supply pipe where the notch is provided in a state where a high frequency is generated from the high frequency generating means using the single crystal manufacturing method apparatus of the present invention. It is characterized by that.

  In the single crystal manufacturing apparatus according to the present invention, since the notch is provided at the tip of the supply pipe, when a high frequency is generated by the high frequency generating means, the induced current due to the high frequency current applied to the supply pipe is suppressed. Can do. Therefore, the temperature rise at the tip of the supply pipe is suppressed, and the melting of the powder raw material inside the supply pipe, particularly in the vicinity of the tip, can be effectively suppressed. Therefore, clogging in the vicinity of the tip of the supply pipe can be prevented, and the powder raw material can be reliably supplied according to the growth rate of the single crystal in the crucible. Therefore, a single crystal having a large uniform composition can be easily obtained.

  When the cutout has a shape extending from the tip of the supply pipe to the side opposite to the tip, an induced current hardly occurs in the circumferential direction at the tip of the supply pipe. Therefore, melting of the powder raw material in the supply pipe can be suppressed more reliably.

  Even if the high-frequency generating means has a high-frequency coil, and the tip of the supply pipe is located in a portion surrounded by the high-frequency coil, according to the present invention, as described above, Since the generation of the induced current is suppressed, the temperature rise inside the supply pipe tip can be suppressed, and the melting and clogging of the powder raw material at the tip of the supply pipe can be reliably suppressed. Moreover, since the supply pipe is close to the crucible, the powder raw material can be reliably supplied by the crucible.

  In the method for producing a single crystal according to the present invention, when a high frequency is applied by the high frequency generation means and the powder raw material is melted in the crucible, even if a high frequency is applied to the supply pipe, a notch is provided. It is possible to reliably suppress melting and clogging of the powder raw material in the vicinity of the tip of the supply pipe. Accordingly, it is possible to easily and reliably provide a large single crystal having a uniform composition using the single crystal manufacturing apparatus of the present invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a schematic front sectional view showing a single crystal manufacturing apparatus according to an embodiment of the present invention.

  The single crystal manufacturing apparatus 1 has a cylindrical heat insulating material 2. Around the heat insulating material 2, a high frequency induction heating coil 3 constituting a high frequency generating means is disposed. A base plate 4 is disposed in the heat insulating material 2, and an inner crucible 5 and an outer crucible 6 are disposed on the base plate 4. The inner crucible 5 has a cylindrical shape, and an upper heater 11 for improving the heat retaining property in the furnace is installed on the upper part. In the present embodiment, the inner crucible 5 is made of iridium, but may be made of other appropriate materials such as platinum, an alloy of platinum and rhodium, and an alloy of platinum and iridium.

  A cylindrical outer crucible 6 is arranged so as to surround the inner crucible 5. The outer crucible 6 can also be composed of an appropriate material such as iridium. In the present embodiment, a double crucible having an inner crucible 5 and an outer crucible 6 in which the inner crucible 5 is arranged concentrically is used.

  A furnace material 7 is disposed outside the outer crucible 6. Further, the periphery of the furnace material 7 is surrounded by a cylindrical heat insulating material 2 surrounding the furnace material.

  In the present embodiment, a supply pipe 9 for supplying the powder raw material to the outside of the inner crucible 5 is disposed. That is, the supply pipe 9 extends from above the heat insulating material 2 to the inside, and the tip end portion 9 a of the supply pipe 9 is positioned outside the inner crucible 5. The powder raw material is charged downward from the tip end portion 9 a, and the portion where the powder raw material is charged is a space between the inner crucible 5 and the inner wall of the outer crucible 6.

  FIG. 2 is a front view of the supply pipe 9. As shown in FIG. 2, the nozzle 10 is attached to the distal end of the supply pipe 9, and the distal end of the nozzle 10 constitutes the distal end portion 9 a of the supply pipe 9.

  The feature of this embodiment is that a notch 10 a is provided in the nozzle 10 attached to the distal end side of the supply pipe 9.

  That is, as shown in the plan view and the front view of FIGS. 3A and 3B, the nozzle 10 is provided with a notch 10 a extending in the vertical direction. Therefore, the notch 10a extends from the distal end portion 9a of the supply pipe 9 in the direction opposite to the distal end portion 9a.

  In the present embodiment, one notch 10a is provided, but a plurality of notches may be provided.

  In the single crystal manufacturing apparatus of the present invention, the powder raw material is supplied from the supply pipe 9 when the single crystal is manufactured. The powder raw material is introduced downward from a nozzle 10 provided on the front end side of the supply pipe 9. In this case, the tip of the nozzle 10, that is, the tip 9 a of the supply pipe 9 is located outside the inner crucible 5, and is a position for reliably supplying the powder raw material to the space between the inner crucible 5 and the outer crucible 6. Is provided. Therefore, the tip portion 9a is located in a region surrounded by the high-frequency coil 3, and the tip portion 9a is close to the crucibles 5 and 6, so that the powder raw material is difficult to scatter around and reliably It is supplied to the space between the outside of the crucible 5 and the outer crucible 6.

  In growing a single crystal, the supplied powder raw material is melted by applying a high-frequency current. The molten raw material moves into the inner crucible 5 through a through hole (not shown) provided in the inner crucible 5, and the seed crystal is immersed in the molten raw material and pulled up in the inner crucible 5. A desired single crystal can be grown by adjusting the pulling rate of the seed crystal.

  The single crystal manufacturing method itself is a known single crystal manufacturing method conventionally referred to as the Czochralski method. The feature of this embodiment is that the supply pipe 9 provided with the notches 10a is used when the powder raw material is supplied from the supply pipe 9 in the production of the single crystal. That is, since the notch 10a is provided, even if a high frequency is applied in the vicinity of the nozzle 10, that is, in the vicinity of the tip 9a of the supply tube 9, an induced current is generated in the supply tube 9 near the tip 9a due to the presence of the notch 10a. Not likely to occur. Therefore, in the nozzle 10, the powder raw material is difficult to be heated and melted. Therefore, since melting of the powder raw material in the nozzle 10 is difficult to occur, clogging in the nozzle 10 is also difficult to occur.

  Therefore, it is possible to reliably and smoothly supply the powder raw material according to the growth rate of the single crystal, thereby easily providing a single crystal having a large uniform composition.

  A specific experimental example will be described.

A nozzle 10 made of platinum metal foil having a notch 10a having a width of 1 mm was attached to the tip of a cylindrical tube made of magnesia and having a cylinder with an outer diameter of 13 mm, an inner diameter of 9 mm, and a length of 400 mm. . The supply pipe 9 is arranged so that the tip end portion 9a of the supply pipe 9 is 5 mm above the upper end 6a of the outer crucible 6, and a tantalum acid having a ratio ratio of 80 mm and a height of 60 mm is obtained by the double crucible method. Lithium was produced. First, an iridium inner crucible 5 having a diameter of 160 mm, a height of 180 mm and a wall thickness of 1.5 mm is arranged concentrically inside an iridium outer crucible 6 having a diameter of 200 mm, a height of 150 mm and a wall thickness of 2.5 mm. A crucible 4 was constructed. A coil having a diameter of 360 mm, a wire diameter of 20 mm, and a turn number of 10 was used as the high-frequency induction heating coil 3. 18 kg of raw material powder with Li ₂ O: Ta ₂ O ₅ = 57: 43 (weight ratio) was supplied from the supply pipe 9, 9 kHz and 550 A high frequency current was passed through the high frequency induction heating coil 3, and the raw material was melted. Thereafter, the seed crystal was brought into contact with the molten raw material, and the seed crystal was pulled up to produce a single crystal.

During the growth of the single crystal, the weight change amount of the single crystal was measured by a weight sensor, and the same amount of powder raw material having a composition of Li ₂ O: Ta ₂ O ₅ = 1: 1 (weight ratio) was supplied to the supply pipe 9 To the space between the inner crucible 5 and the outer crucible 6. As a result, it was possible to obtain a lithium tantalate single crystal having a constant ratio composition with a diameter of 80 mm and a height of 60 mm without clogging the supply pipe 9 during single crystal growth.

In general, the ratio of Li ₂ O to Ta ₂ O ₅ in the composition of the lithium tantalate single crystal can be estimated at the Curie temperature. When Li ₂ O: Ta ₂ O ₅ = 1: 1, the Curie temperature is 690 ° C., and when Li ₂ O: Ta ₂ O ₅ = 0.96: 1, the Curie temperature is 615 ° C. When the upper and lower Curie temperatures of the lithium tantalate single crystal obtained as described above were measured by a differential thermal analyzer, the Curie temperature of the upper part of the crystal was 688 ° C., and the Curie temperature of the lower part of the crystal was 690 ° C. there were. Therefore, it was confirmed that the composition in the single crystal was almost uniform.

  On the other hand, for comparison, a nozzle 110 configured in the same manner except that the notch shown in FIGS. 4A and 4B is not provided is used, and the others are exactly the same as the above experimental example. An attempt was made to produce a lithium tantalate single crystal. However, the raw material was clogged in the supply tube 9 during the production, and the Curie temperature in the obtained single crystal was 688 ° C. at the upper part of the crystal and the Curie temperature at the lower part of the crystal was 695 ° C. That is, it can be seen that the composition varies within the single crystal. Further, when the supply pipe after cooling was confirmed, it was confirmed that the raw material was melted and clogged at the tip. That is, it is considered that the tip of the supply pipe was heated to a temperature higher than about 1550 ° C., which is the melting point of lithium tantalate.

  In the above embodiment, the double crucible is used. However, the single crystal manufacturing apparatus according to the present invention does not necessarily need to be a double crucible. If the crucible is not a double crucible, the tip of the supply pipe may be positioned in the crucible. Even in that case, according to the present invention, the notch is provided at the tip of the supply pipe. It is difficult for clogging at the tip.

  Further, in the above embodiment, the notch is provided so as to extend from the distal end portion of the supply pipe in the direction opposite to the distal end portion. Therefore, the supply pipe is inclined so that the notch is directed upward. If attached, the probability that the powder will scatter from the notch is reduced. However, the shape of the notch is not limited to this, and may be provided so as to extend obliquely upward from the tip portion, for example.

  In the above-described embodiment, the nozzle 10 is attached to the tip of the supply pipe to configure the supply pipe 9. However, the nozzle 10 is not necessarily provided, and in that case, the tip of the cylindrical supply pipe is used. A notch may be provided in the.

1 is a front sectional view of a single crystal manufacturing apparatus according to an embodiment of the present invention. The front view for demonstrating the supply pipe | tube used for the single crystal manufacture shown in FIG. The top view and front view for demonstrating the nozzle of the supply pipe front-end | tip part in which the notch is provided in the single crystal manufacturing apparatus shown in FIG. (A) And (b) is a top view front view of the nozzle prepared for the comparison. The schematic block diagram which shows an example of the conventional single crystal manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing apparatus 2 ... Heat insulating material 3 ... High frequency induction heating coil 4 ... Base plate 5 ... Inner crucible 5a ... Small diameter part 5b ... Large diameter part 6 ... Outer crucible 7 ... Heat insulating material 9 ... Supply pipe 9a ... Tip part 10 ... Nozzle 10a ... Notch

Claims (4)

A supply pipe for supplying powder raw material from the tip part, a powder raw material is supplied from the tip part of the supply pipe, a crucible containing the supplied powder raw material, and the powder raw material in the crucible are heated and melted In a single crystal manufacturing apparatus comprising a high frequency generating means for
The single crystal manufacturing apparatus, wherein a notch is provided at the tip of the supply pipe.   The single crystal manufacturing apparatus according to claim 1, wherein the notch has a shape extending from a distal end portion of the supply pipe in a direction opposite to the distal end portion.   The high-frequency generating means has a high-frequency coil, and the high-frequency coil is disposed so as to surround the crucible, and a notch provided at a distal end portion of the supply pipe is located in a region surrounded by the high-frequency coil. The single crystal manufacturing apparatus according to claim 1, wherein the supply pipe is close to the crucible. In the method for producing a single crystal, the powder raw material is melted in a crucible, the seed crystal is immersed in the molten raw material, and the single crystal is grown while pulling up the seed crystal.
Using the single crystal manufacturing method device according to any one of claims 1 to 3, in a state where a high frequency is generated from the high frequency generating means, the tip of the supply pipe is provided with the notch. A method for producing a single crystal, comprising supplying a powder raw material into the crucible.

Images