JP3550495B2 - Single crystal manufacturing apparatus and single crystal manufacturing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal manufacturing apparatus, and more particularly to a manufacturing apparatus for manufacturing a single crystal by a pulling-down method.And manufacturing methodIt is about.
[0002]
[Prior art]
Recently, lithium tantalate LiTaO₃(Hereinafter referred to as LT), lithium niobate LiNbO₃(Hereinafter referred to as LN), lithium tetraborate Li₂B₄O₇Various surface acoustic wave devices have been produced using a single crystal of an oxide such as LBO.
These single crystals have a larger electromechanical coupling coefficient (K²) Is obtained, and LT and LBO have a cutting angle of zero temperature coefficient. Therefore, by using these single crystals for the surface acoustic wave device, terminals such as mobile phone devices can be downsized and highly functional. It became to be. Among the above oxides, LBO belongs to a tetragonal system of 4 mm, and this single crystal has a delay time temperature coefficient of almost 0 ppm / ° C, an electromechanical coupling coefficient of about 6 times larger than that of quartz, and mechanical reflection. Since is larger than LT and LN, it is drawing attention as a material suitable for miniaturization of a surface acoustic wave device.
LBO single crystal growth methods are roughly classified into the following three methods. That is, the Czochralski method (Cz method, rotation raising method), the Vertical Bridgman method (VB method), and the lowering method.
In the Czochralski method, as shown in FIG. 2, a raw material to be crystallized is placed in a platinum crucible 41, and the raw material is heated to a melting point or higher in an electric furnace 42 and melted. This is a method of growing a crystal 45 from the lower end of the seed crystal 44 by immersing the lower end of the seed crystal 44 and pulling it up while rotating it slowly.
In the vertical Bridgman method, as shown in FIG. 3, a raw material to be crystallized is placed in a platinum crucible 51, and the raw material is heated to a melting point or higher in an electric furnace 52 and melted. The plate-shaped seed crystal 53 is put into the furnace, and the platinum crucible 51 is gradually moved from the high-temperature side to the low-temperature side with the seed crystal 53 side as a tip in a state where a temperature gradient is formed in the electric furnace 52, so that the seed crystal This is a method of sequentially growing crystals from the 53 side.
One of the inventors of the present application describes the reduction method in the literature (Journalof the Ceramic Society of Japan 105 [7] 1997), and as shown in FIG.Pore 61aThe polycrystalline raw material is placed in a platinum crucible 61 provided with the above, and the platinum crucible 61 is placed at the position where the temperature gradient is steepest in the electric furnace 62 in which the upper side is kept at the melting point of the raw material or more and the lower side is kept at the melting point of the raw material or less. Dispose the raw materials by placing them,Pore 61aThis is a method in which the seed crystal 63 is rotated and pulled down while the upper end of the rod-shaped seed crystal 63 is in contact with the raw material melt that has flowed out by gravity. This lowering method is based on the method ofPore 61aUtilizing the wettability and surface tension of the raw material melt leaked from the platinum crucible 61 and growing the crystal while holding the raw material melt between the platinum crucible 61 and the seed crystal 63, as in the case of LBO Suitable for growing crystals with high viscosity during melting.
[0003]
[Problems to be solved by the invention]
However, the Czochralski method is suitable for growing crystals of a material having a relatively low melt viscosity such as Si (silicon), LT, and LN. However, LBO is more suitable for melt growth than Si, LT, and LN. Because of its high viscosity, bubbles and cracks are liable to enter during the growth process. For this reason, there is a problem that the growth rate of the LBO single crystal by the Czochralski method is about 0.3 mm / h, which is one tenth or less as compared with other crystals of Si, LT, LN and the like. Further, there is a problem that a crystal manufacturing apparatus using the Czochralski method is generally more expensive than a crystal manufacturing apparatus using another method such as the Bridgman method or the pulling-down method.
In addition, the vertical Bridgman method is currently a standard method for growing LBO single crystals, but a platinum crucible must be newly prepared every time an LBO single crystal is grown, and the manufacturing cost is increased. Is high. Therefore, in many cases, an amorphous LBO sintered body, which is more expensive than a powder raw material, is used as a raw material in order to increase the amount of the raw material charged into the platinum crucible and reduce the use of the platinum crucible. Further, in the vertical Bridgman method, it is not possible to perform crystal growth while observing the state of crystal growth on the spot, and it is not possible to judge the quality of the crystal only after the completion of the growth, or the growth rate is 0.3 mm / h to 0 mm. There was also a problem that the production cost was increased because crystal growth took too long, as slow as about 0.5 mm / h.
Furthermore, in both the Czochralski method and the Vertical Bridgman method, since the viscosity of the LBO melt is large, moisture and bubbles in the melt are likely to remain, and the moisture and bubbles may be included in the crystal. Many.
Further, in the pulling-down method, since the flow rate of the melt flowing out of the pores at the bottom of the platinum crucible changes according to the amount of the melt in the crucible, a high-quality unit having many straight body portions, that is, portions having a uniform diameter. There was a problem that it was difficult to obtain crystals. That is, when the amount of melt in the crucible is large, the flow rate of the melt flowing out of the pores is also large, but since the flow rate decreases as the amount of melt in the crucible decreases, the straight body part is increased. In order to obtain it, it was necessary to gradually decrease the growth rate from the start to the end of the growth, and it was difficult to control the furnace temperature and the seed crystal pull-down speed for that purpose.
In addition, in any of the growing methods, the raw material volume in the crucible is limited, so that the size (length, diameter, etc.) of the grown crystal is limited.
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a single crystal manufacturing apparatus capable of continuously and easily manufacturing high quality single crystals at low cost, including materials having a high viscosity such as LBO.And single crystal manufacturing methodIs to provide.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a single crystal production apparatus according to the invention of claim 1 arranges a crucible containing a raw material in an electric furnace, maintains the crucible at a temperature equal to or higher than the melting point of the raw material, and In a single crystal manufacturing apparatus using a pull-down method of growing a crystal by rotating the seed crystal while rotating the seed crystal in a state where the upper end of the seed crystal is in contact with the raw material melt leaked from the pore formed at the bottom, A raw material melting tank for melting a powder raw material (a raw material in a powder state) to generate a raw material melt; a powder raw material supply means for supplying a powder raw material to the raw material melting tank; and a raw material melt in the raw material melting tank And a raw material melt introducing means for introducing the melt into the crucible.The raw material melting tank is provided at a position higher than the crucible in the electric furnace, and is disposed at an electric furnace element part having a higher temperature than the crucible.It is characterized by:
According to the single crystal manufacturing apparatus configured as described above, the powder raw material is supplied to the raw material melting tank by the powder raw material supply means, and the powder raw material is melted in the raw material melting tank to generate a raw material melt. By introducing the melt into the crucible by the raw material melt introducing means, the crystal growth can be performed while supplying the raw material melt into the crucible, so that the amount of the melt in the crucible from the beginning to the end of the crystal growth can be increased. Is maintained substantially constant, and the crystal growth can be performed while maintaining the flow rate of the raw material melt from the pores at the bottom of the crucible substantially constant.
The single crystal manufacturing apparatus according to the invention described in claim 2 isA crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal manufacturing apparatus that grows a crystal by rotating and pulling down a seed crystal in a rotated state, a raw material melting tank for melting a raw powder material to produce a raw material melt, and supplying the raw powder material to the raw material melting tank Powder raw material supply means, and a raw material melt introducing means for introducing the raw material melt in the raw material melting tank into the crucible,A powder raw material supply means for storing a powder raw material, a dry gas introducing means for introducing a dry gas into the powder raw material in the powder raw material tank, and a transfer of the powder raw material from the powder raw material tank to the raw material melting tank; And a raw material transfer means for carrying out the process.
According to the single crystal manufacturing apparatus configured as described above, by introducing dry air into the powder raw material to remove the moisture of the raw material powder, the raw material powder is prevented from agglomerating due to moisture, and the component ratio is transferred to the raw material melting tank. A certain powder raw material can be supplied stably.
According to a third aspect of the present invention, there is provided a single crystal manufacturing apparatus, wherein the raw material melting tank in claim 2 is arranged in an electric furnace together with the crucible, and the raw material transfer means transfers the powder raw material to the raw material melting tank. To this end, a transfer tube having one end inserted into the powder material tank and the other end inserted into the electric furnace is provided, and cooling means for cooling the transfer tube from the outside is provided.
According to the single crystal manufacturing apparatus configured as described above, the crucible and the raw material melting tank can be heated by one electric furnace, so that the apparatus configuration can be simplified and the raw material in the electric furnace can be heated from outside the electric furnace. By cooling the transfer pipe for transferring the powder raw material to the melting tank, the powder raw material is prevented from melting in the middle of the transfer pipe and the transfer pipe can be prevented from being clogged.
The single crystal manufacturing apparatus according to the invention described in claim 4 is:A crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal manufacturing apparatus that grows a crystal by rotating and pulling down a seed crystal in a rotated state, a raw material melting tank for melting a raw powder material to produce a raw material melt, and supplying the raw powder material to the raw material melting tank Powder raw material supply means, and a raw material melt introducing means for introducing the raw material melt in the raw material melting tank into the crucible,The raw material melting tank is arranged at a position higher than the crucible, and the raw material melt introducing means transmits the raw material melt leaking from the hole formed at the bottom of the raw material melting tank and flowing down the surface of the crucible. It is characterized by having a guide member for guiding inside.
According to the single crystal manufacturing apparatus configured as described above, the raw material melt leaking from the bottom of the raw material melting tank is transmitted down the surface of the guide member, is dropped by its own weight, and is supplied into the crucible. Moisture and impurities remaining in the melt can be removed by evaporating with heat of an electric furnace before entering the crucible.
The invention according to claim 5 is5. The apparatus for producing a single crystal according to claim 1, wherein the crucible has an inverted conical shape having a tapered angle θ at a bottom, and has a plurality of pores at the bottom. It is characterized by.
The invention according to claim 6 is:A crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal manufacturing method for growing a crystal by rotating and pulling down a seed crystal in a tilted state, a raw material melting tank for generating a raw material melt by melting a powder raw material above the crucible in the electric furnace is provided. In addition, the raw material melting tank is disposed in an electric furnace element part having a higher temperature than the crucible, a powder raw material tank is provided outside the electric furnace to accommodate the powder raw material, and the raw material melting tank is transferred from the powder raw material tank through a transfer pipe. By supplying the powdered raw material into the melting tank, melting the powdered raw material in the raw material melting tank and then introducing the raw material into the crucible, the raw material melt is continuously supplied into the crucible, and the bottom of the crucible is Raw material melt from pores It is characterized in that to perform the crystal growth while maintaining the outflow substantially constant.
The invention according to claim 7 isA crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal manufacturing method for growing a crystal by rotating and pulling down a seed crystal in a tilted state, a raw material melting tank for generating a raw material melt by melting a powder raw material above the crucible in the electric furnace is provided. Providing a powder raw material tank for containing the powder raw material outside the electric furnace, supplying the powder raw material into the raw material melting tank through the transfer pipe from the powder raw material tank, and melting the powder raw material in the raw material melting tank. By introducing the raw material melt into the crucible from above, the crystal is grown while keeping the flow rate of the raw material melt from the pores at the bottom of the crucible substantially constant. , Further, the powder raw material tank A dry gas is introduced into the powder raw material to remove the moisture of the powder raw material, and a transfer pipe for transferring the powder raw material from the powder raw material tank to the raw material melting tank is provided, and the transfer pipe is cooled from the outside. It is characterized in that the powder raw material is transferred.
The invention according to claim 8 isThe method for producing a single crystal according to claim 6, wherein a guide member for guiding the raw material melt from the raw material melting tank into the crucible is provided, and the guide member leaks from a fine hole formed in a bottom portion of the raw material melting tank. The material melt flowing down is transmitted along the surface of the guide member and supplied into the crucible.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.
FIG. 1A is a schematic overall configuration diagram showing an example of an embodiment of a single crystal manufacturing apparatus 1 according to the present invention. In this example, a case where an LBO single crystal is manufactured will be described.
In FIG. 1A, 10 is an electric furnace, 20 is a powder raw material supply device, and 30 is a crystal pulling-down device.
The electric furnace 10 has a structure in which three cylindrical electric furnace elements 10a, 10b, and 10c are vertically stacked and connected to each other. A platinum crucible 2 is provided at a lower portion of the electric furnace 10, and a platinum raw material is provided at an upper portion. A melting tank (hereinafter, referred to as a pre-melt crucible) 3 is provided. A platinum rod 4 is provided between the pre-melt crucible 3 and the platinum crucible 2 to guide 5 m of the LBO raw material melt generated in the pre-melt crucible 3 into the platinum crucible 2. .
The electric furnace element 10a at the top of the electric furnace 10 heats the premelt crucible 3 to a temperature equal to or higher than the melting point of LBO (for example, 995 ° C.). The middle electric furnace element 10b heats the platinum crucible 2 to a temperature equal to or higher than the melting point of LBO (for example, 970 ° C.). The lowermost electric furnace element 10c is set to a temperature lower than the melting point of LBO (for example, 690 ° C.). As a result, a gentle temperature gradient is formed from the middle portion to the lowermost portion, and has an annealing effect of removing distortion of the grown crystal. A viewing window 17 is provided on the side wall of the electric furnace 10 so that the vicinity of the lower portion of the platinum crucible 2, that is, the crystal growth portion can be visually observed from outside the furnace. The viewing window 17 is hermetically closed with heat-resistant glass.
The powder raw material supply device 20 includes a powder raw material tank 6 for accommodating the LBO powder raw material 5p, a raw material introduction pipe 7 for introducing the powder raw material 5p from the powder raw material supply source (not shown) into the powder raw material tank 6, and a raw material introduction pipe 7 not shown. A dry gas introduction pipe 8 for introducing a dry gas (dry air, nitrogen, argon, helium, etc.) into the powder raw material 5p in the powder raw material tank 6 from the dry gas generation source; And a raw material transfer device 21 for transferring the powder raw material 5p to the raw material 3.
[0006]
The raw material transfer device 21 has a transfer pipe 9 having an upper end inserted into the bottom 6 a of the powder raw material tank 6 and a lower end inserted into the electric furnace 10 for transferring the powder raw material 5 p to the raw material melting tank 3, and cooling the transfer pipe 9. And a powder supply pump 12 provided in the transfer pipe 9 to forcibly transfer the powder raw material 5p. The transfer pipe 9 and the cooling jacket 11 are inserted into a through hole 13 formed in the center of the upper lid 10 d of the electric furnace 10, and the lower end of the transfer pipe 9 reaches the inside of the raw material melting tank 3. The cooling jacket 11 is provided so as to surround the outer circumference of the transfer pipe 9, and the inside of the transfer pipe 9 is cooled by heat from the electric furnace 10 by cooling the transfer pipe 9 from the outside with a refrigerant passing through the inside. In contrast, it is kept below the melting point temperature of LBO. The crystal pulling-down device 30 has a columnar rotating rod 15 having a holding portion 15a for holding the seed crystal 14 at its upper end, and holds the rotating rod 15 in a vertical posture and moves up and down while rotating the shaft. And a rotation lowering device 16. FIG. 1B shows the structure of the premelt crucible 3 and the platinum rod 4, and FIG. 1C shows the structure of the platinum crucible 2.
[0007]
As shown in FIG. 1B, a hole 3a is opened at the center of the bottom of the pre-melt crucible 3, and the upper end of the platinum rod 4 is inserted into the hole 3a. The diameter of the hole 3 a is set slightly larger than the diameter of the platinum rod 4, and the molten material 5 m leaking from the hole 3 a flows down the surface of the platinum rod 4 and is naturally guided into the platinum crucible 2. It is a mechanism that is done.
As shown in FIG. 1C, the bottom of the platinum crucible 2 is formed in a funnel shape (inverted conical shape), and a plurality of pores having the same diameter (for example, 0.5 mm) are formed in the center of the bottom and the periphery thereof. 2a, 2a,... Are provided, and by flowing out the raw material melt 5m from the plurality of pores 2a, 2a,. The structure is such that crystals can be grown while holding 5 m of the raw material melt between itself and the upper surface.
[0008]
According to the single crystal manufacturing apparatus 1 configured as described above, an LBO single crystal can be manufactured as follows.
First, the temperature of the electric furnace elements 10a and 10b of the electric furnace 10 is set to be equal to or higher than the melting point temperature of LBO, and the temperature of the electric furnace element 10c is set to be lower than the melting point temperature of LBO to start heating the furnace. When the temperature is reached, maintain that condition. A coolant is always flowed through the cooling jacket 11, and a dry gas is always introduced into the powder material 5 p in the powder material tank 6 through the dry gas introduction pipe 8.
Thereafter, the powder supply pump 12 is operated to supply a predetermined amount of the powder raw material 5p from the powder raw material tank 6 to the pre-melt crucible 3 through the transfer pipe 9. The powdered raw material 5p supplied into the pre-melt crucible 3 is heated and melted by the electric furnace 10 to become a raw material melt 5m, and starts to leak out from the hole 3a at the bottom of the pre-melt crucible 3. Then, the raw material melt 5m flows down the surface of the platinum rod 4 to introduce the raw material melt 5m into the platinum crucible 2.
When the raw material melt 5m accumulates in the platinum crucible 2, the raw material melt 5m starts leaking from the plurality of fine holes 2a, 2a,. Since this situation can be observed through the viewing window 17 of the electric furnace 10, when leakage of the raw material melt 5 m is confirmed, the rotating rod 15 is raised by the rotating lowering device 16 and held by the rotating rod 15. The tip (upper end) of the seed crystal 14 is brought into contact with 5 m of the raw material melt wetting the lower surface of the platinum crucible 2.
Thereafter, while maintaining the state in which the tip of the seed crystal 14 is in contact with the raw material melt 5 m, the rotating rod 15 is rotated at a predetermined speed (for example, 30 rpm) by the rotation lowering device 16 at a constant speed. The crystal 18 is grown from the tip of the seed crystal 14 by lowering the crystal 18 at, for example, 0.75 mm / h.
[0009]
At this time, by controlling the supply amount of the powder raw material 5p into the pre-melt crucible 3 and controlling the introduction amount of the raw material melt 5m into the platinum crucible 2, the crystal growth in the platinum crucible 2 from the beginning to the end of crystal growth is controlled. The crystal 18 is grown while keeping the amount of the raw material melt 5m substantially constant, and keeping the amount of the raw material melt 5m flowing out from the bottom pores 2a, 2a,... Of the platinum crucible 2 substantially constant.
By keeping the flow rate of the raw material melt 5m from the pores 2a, 2a,... At the bottom of the platinum crucible 2 substantially constant, the raw material supplied per unit time to the upper surface of the growing crystal 18 is maintained. The amount of 5 m of melt is kept almost constant during crystal growth.
[0010]
Therefore, the single crystal manufacturing apparatus 1 of the present embodiment has the following excellent advantages.
That is, since the amount of the raw material melt 5 m supplied per unit time on the upper surface of the growing crystal 18 can be kept substantially constant during the crystal growth, the powder raw material 5 p is continuously transferred from the powder raw material tank 6 to the pre-melt crucible 3. By growing the crystal while supplying it, a long LBO single crystal having many straight bodies can be obtained.
As the powder raw material 5p to be put into the powder raw material tank 6, LBO powder or Li₂  O and B₂  O₃  The raw material cost can be reduced as compared with the vertical Bridgman method using an amorphous LBO sintered body as a raw material. In addition, the use of rod-like seeds as in the case of the Czochralski method is also advantageous in reducing production costs.
[0011]
In addition, since the vapor pressure at the time of melting a raw material of a multi-element single crystal such as LBO differs for each raw material component, the composition of the raw material melt changes, causing a change in the composition of a grown crystal or a uniform change due to a change in viscosity of the raw material melt. In many cases, it is impossible to grow a suitable crystal. However, according to the single crystal production apparatus 1 of the present embodiment, the component ratio of the raw material powder 5p is adjusted in advance in view of the composition change at the time of melting the raw material. In addition, a uniform crystal having no composition fluctuation can be grown.
Further, since dry air is introduced into the powder raw material 5p in the powder raw material tank 6 to remove the moisture of the raw material powder 5p, the raw material powder 5p is prevented from aggregating due to the moisture, and the component ratio is kept constant in the pre-melt crucible 3. Powder material 5p can be supplied stably.
Further, since the transfer pipe 9 for transferring the powder raw material 5p from outside the electric furnace 10 to the pre-melt crucible 3 in the electric furnace 10 is cooled, the powder raw material 5p is prevented from being melted in the transfer pipe 9. The transfer pipe 9 can be prevented from being clogged, and the powder material 5p can be stably supplied to the pre-melt crucible 3.
Further, the raw material melt 5m leaking and flowing down from the hole 3a formed at the bottom of the premelt crucible 3 is guided along the surface of the platinum rod 4 into the platinum crucible 2 so as to be guided into the platinum crucible 2. The water and impurities remaining in the raw material melt 5m generated in the above can be evaporated and removed by the heat of the electric furnace before entering the platinum crucible 2, so that a high-quality crystal containing no bubbles or impurities can be grown. it can.
[0012]
In addition, since the viewing window 17 is provided on the side wall of the electric furnace 10 so that the crystal growing portion can be observed on the spot, the seeding portion and the shoulder portion can be easily controlled.
Also, the number, position, size, bottom shape of the platinum crucible 2, taper angle θ (see FIG. 1 (c)), etc., are appropriately set for the plurality of pores 2a, 2a,. This makes it possible to increase the diameter of the grown crystal.
Further, by controlling the electric furnace 10, the powder raw material supply device 20, the raw material transfer device 21, the crystal lowering device 30 and the like by computer, it is also possible to automatically grow a high quality LBO single crystal.
In the above-described embodiment, the case where an LBO single crystal is manufactured has been described as an example. However, the single crystal manufacturing apparatus 1 having the above-described configuration may be used for rutile used for a material of an optical isolator and BGO used for a material of a scintillator. , BSO, CLBO which is a kind of non-linear optical material, and LN, LT which is known as a piezoelectric / optical material.
[0013]
【The invention's effect】
As described above, the present invention has the following excellent effects. According to the first aspect of the present invention, in a single crystal manufacturing apparatus using a pull-down method, a powder raw material is supplied to a raw material melting tank by a powder raw material supply means, and the raw material melt is melted in the raw material melting tank to form a raw material melt. The raw material melt is produced and introduced into the crucible by the raw material melt introducing means, so that the crystal growth can be performed while the raw material melt is continuously supplied into the crucible. Can easily and at high quality produce a single crystal of a substance having a large value.
According to the second aspect of the present invention, since dry air is introduced into the powder raw material to remove the moisture of the raw material powder, aggregation of the raw material powder due to moisture is prevented, and a constant component ratio is supplied to the raw material melting tank. Powder material can be supplied stably.
According to the third aspect of the present invention, since the crucible and the raw material melting tank can be heated by one electric furnace, the configuration of the apparatus can be simplified. In addition, since the transfer pipe that transfers the powder material from the outside of the electric furnace to the raw material melting tank in the electric furnace is configured to be cooled, the melting of the powder material is prevented by preventing the powder material from melting and clogging in the transfer pipe. The powder raw material can be stably supplied to the tank.
Further, in the invention according to claim 4, the raw material melt leaking from the hole formed at the bottom of the raw material melting tank and flowing down is guided along the surface of the guide member and guided into the crucible, Grow high-quality crystals that do not contain air bubbles or impurities because water and impurities remaining in the raw material melt generated in the raw material melting tank can be removed by evaporation in the electric furnace before entering the crucible. Can be.
Further, in the invention according to claim 5, in the method for producing a single crystal using the pulling-down method, a raw material melting tank for melting a raw material powder to generate a raw material melt is provided above a crucible in an electric furnace, A powder raw material tank for containing the powder raw material is provided outside the electric furnace, the powder raw material is supplied from the powder raw material tank into the raw material melting tank through a transfer pipe, and the powder raw material is melted in the raw material melting tank, and then the crucible is cooled. The raw material melt is continuously supplied into the crucible by introducing it into the crucible, and the crystal is grown while keeping the flow rate of the raw material melt from the pores at the bottom of the crucible almost constant. Solidification of substances with high viscosity of melt Crystals can be produced easily and with good quality at low cost.
Further, in the invention according to claim 6, since dry air is introduced into the powder raw material to remove the moisture of the raw material powder, aggregation of the raw material powder due to moisture is prevented, and a constant component ratio is supplied to the raw material melting tank. Powder material can be supplied stably.
Further, in the invention described in claim 7, the crucible and the raw material melting tank can be heated by one electric furnace, so that the configuration of an apparatus used for producing a single crystal can be simplified. In addition, since the transfer pipe that transfers the powder material from the outside of the electric furnace to the raw material melting tank in the electric furnace is configured to be cooled, the melting of the powder material is prevented in order to prevent the powder material from melting and clogging in the transfer pipe. The powder raw material can be stably supplied to the tank.
In the invention according to claim 8, the raw material melt leaking from the hole formed at the bottom of the raw material melting tank and flowing down is transmitted through the surface of the guide member and supplied into the crucible. Grow high-quality crystals that do not contain bubbles or impurities because water and impurities remaining in the raw material melt generated in the raw material melting tank can be removed by evaporation in the electric furnace before entering the crucible. Can be.
[Brief description of the drawings]
FIG. 1A is a schematic overall configuration diagram showing an example of an embodiment of a single crystal manufacturing apparatus according to the present invention, and FIGS. 1B and 1C are partially enlarged cross-sectional views of the single crystal manufacturing apparatus shown in FIG. It is a figure
FIG. 2 is an explanatory view showing an example of a conventional single crystal manufacturing apparatus.
FIG. 3 is an explanatory view showing an example of a conventional single crystal manufacturing apparatus.
FIG. 4 is an explanatory view showing an example of a conventional single crystal manufacturing apparatus.
[Explanation of symbols]
1: Single crystal production equipment 2: Platinum crucible 2a: Pore
3: Premelt crucible (raw material melting tank) 3a: Hole 4: Platinum rod (melt introduction means, guide member)
5p: End material 6: Powder material tank 6a: Bottom 7: Material introduction pipe
8: Dry gas introduction pipe 9: Transfer pipe
10: electric furnace 10a, 10b, 10c: electric furnace element 10d: top lid
11: Cooling jacket (cooling means) 12: Powder supply pump
14: Seed crystal 15: Rotating rod 16: Rotation lowering device
17: Viewing window 20: Powder material supply device 21: Material transfer device

Claims (8)

A crucible containing the raw material is placed in an electric furnace, and the temperature is kept at a temperature equal to or higher than the melting point of the raw material. In a single crystal production apparatus that grows crystals by pulling down while rotating the seed crystal in the
A raw material melting tank for melting a powder raw material to generate a raw material melt,
Powder raw material supply means for supplying a powder raw material to the raw material melting tank,
Raw material melt introducing means for introducing the raw material melt in the raw material melting tank into the crucible ,
The single crystal production, characterized in that the raw material melting tank is arranged at a position higher than the crucible in the electric furnace, and is arranged in an electric furnace element part having a higher temperature than the crucible. apparatus. A crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal production apparatus that grows crystals by pulling down while rotating the seed crystal in the
A raw material melting tank for melting a powder raw material to generate a raw material melt,
Powder raw material supply means for supplying a powder raw material to the raw material melting tank,
Raw material melt introducing means for introducing the raw material melt in the raw material melting tank into the crucible,
The powder raw material supply means,
A powder raw material tank for storing the powder raw material,
Dry gas introducing means for introducing a dry gas into the powder raw material in the powder raw material tank;
A single crystal production apparatus comprising: a raw material transfer means for transferring a powder raw material from the powder raw material tank to the raw material melting tank. The raw material transfer means,
A transfer pipe having one end inserted into the electric furnace and the other end inserted into the powder raw material tank to transfer the powder raw material to the raw material melting tank,
The apparatus for producing a single crystal according to claim 2, further comprising cooling means for cooling the transfer pipe from outside. A crucible containing the raw material is placed in an electric furnace and kept at a temperature equal to or higher than the melting point of the raw material, and the upper end of the seed crystal is brought into contact with the raw material melt leaking from the pores formed at the bottom of the crucible. In a single crystal production apparatus that grows crystals by pulling down while rotating the seed crystal in the
A raw material melting tank for melting a powder raw material to generate a raw material melt,
Powder raw material supply means for supplying a powder raw material to the raw material melting tank,
Raw material melt introducing means for introducing the raw material melt in the raw material melting tank into the crucible,
The raw material melting tank is arranged at a position higher than the crucible,
The raw material melt introduction means,
An apparatus for producing a single crystal, comprising: a guide member for guiding a raw material melt leaking from a fine hole formed at a bottom portion of the raw material melting tank and flowing down to the inside of the crucible through the surface thereof . 5. The single crystal according to claim 1, wherein the crucible has an inverted conical shape with a bottom portion having a taper angle θ and a plurality of pores provided in the bottom portion. 6. manufacturing device.   A crucible containing the raw material is placed in an electric furnace, and the temperature is kept at a temperature equal to or higher than the melting point of the raw material. To grow the crystal by rotating and pulling the seed crystal down In the method for producing a crystal,
  A raw material melting tank is provided above the crucible in the electric furnace to melt the powdery raw material to generate a raw material melt, and the raw material melting tank is disposed in an electric furnace element part having a higher temperature than the crucible. And
  Providing a powder raw material tank containing the powder raw material outside the electric furnace,
  Supplying the powder raw material into the raw material melting tank through the transfer pipe from the powder raw material tank,
  By melting the powdered raw material in the raw material melting tank and then introducing the raw material into the crucible, the raw material melt is continuously supplied into the crucible,
  The crystal was grown while keeping the flow rate of the raw material melt from the pores at the bottom of the crucible almost constant.
A method for producing a single crystal, comprising:   A crucible containing the raw material is placed in an electric furnace, and the temperature is kept at a temperature equal to or higher than the melting point of the raw material. In the single crystal manufacturing method of growing the crystal by pulling down while rotating the seed crystal in a state where
  A raw material melting tank for melting a raw material powder to produce a raw material melt is provided above the crucible in the electric furnace,
  Providing a powder raw material tank containing the powder raw material outside the electric furnace,
  Supplying the powder raw material into the raw material melting tank through the transfer pipe from the powder raw material tank,
  By melting the powdered raw material in the raw material melting tank and then introducing the raw material into the crucible, the raw material melt is continuously supplied into the crucible,
  In order to grow the crystal while keeping the flow rate of the raw material melt from the pores at the bottom of the crucible substantially constant,
  Further, while introducing a dry gas into the powder raw material in the powder raw material tank to remove the moisture of the powder raw material,
  A transfer pipe for transferring the powder raw material from the powder raw material tank to the raw material melting tank was provided, and the transfer raw material was transferred while cooling the transfer pipe from the outside.
A method for producing a single crystal, comprising:   Providing a guide member for guiding the raw material melt from the raw material melting tank into the crucible,
  The raw material melt leaking from the pores formed at the bottom of the raw material melting tank and flowing down is transmitted to the surface of the guide member and supplied into the crucible.
The method for producing a single crystal according to claim 6, wherein:

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