JP6606638B2 - Method and apparatus for growing Fe-Ga based alloy single crystal - Google Patents

Description

  The present invention relates to a method and an apparatus for growing an Fe—Ga based alloy single crystal.

Fe-Ga based alloys are attracting attention as materials used in actuators, vibration power generation, and the like because they exhibit large magnetostriction. Note that a part of Ga, for example, Al, Sn or other elements is also included in the Fe—Ga based alloy.
Since the magnetostriction characteristics of this alloy greatly depend on the chemical composition and crystal orientation, it is necessary to strictly control the chemical composition and crystal orientation.
Crystals having a certain composition and orientation have been produced mainly by a rapid solidification method (Patent Document 1), a Bridgman method, and an abnormal grain growth method (Non-Patent Documents 1 and 2).

JP 2007-214297 A

Y. -H. Yoo et al. : J. Applied Physics, 103 (2008), 07B325, S. -M. et al. Scripta Mater. , 66 (2012), 307.

In the conventional method described in the prior art, it is difficult to produce a large amount of inexpensive single crystals.
An object of the present invention is to provide a method and an apparatus for growing an Fe—Ga based alloy single crystal capable of producing a large crystal with high accuracy and low chemical composition and crystal orientation.
The production method of the Fe—Ga based alloy single crystal in the CZ method can be grown and produced by a high frequency induction heating method. However, according to this method, the quality of the grown single crystal is not necessarily good. The present inventor investigated the cause of the deterioration of the quality of the grown single crystal. In this method, some suspended matter is seen on the surface of the melt during growth. When the suspended matter was investigated with the idea that the suspended matter might be the cause of the deterioration of the quality of the grown single crystal, it was clarified that the suspended matter was Ga oxide, Ga-Al-OC compound, etc. did.
The present invention provides a method and apparatus for growing an Fe-Ga based alloy single crystal aimed at improving the efficiency of production and improving the quality by suppressing the generation of suspended matters on the melt surface during the growth and production. The purpose is to do.

In the method for growing an Fe—Ga based alloy single crystal according to the present invention, the crucible is a double crucible including an outer crucible and an inner crucible arranged in the outer crucible, and the high frequency induction arranged outside the outer crucible. After heating with a heating source and bringing the seed crystal into contact with the raw material melt in the inner crucible, the seed crystal is pulled up to grow a single crystal.

In the method for growing an Fe—Ga based alloy single crystal of the present invention, it is preferable that the outer crucible is a graphite crucible and the inner crucible is an alumina crucible.
Method for growing Fe-Ga-based alloy single crystal of the present invention, it is preferable that the material of the inner crucible and the non-oxide ceramics.
Method for growing Fe-Ga-based alloy single crystal of the present invention, the non-oxide ceramics, preferably a boron nitride.
In the method for growing an Fe—Ga based alloy single crystal of the present invention, it is preferable to provide a spacer between the bottom surface of the outer crucible and the inner crucible.
In the method for growing an Fe—Ga based alloy single crystal of the present invention, it is preferable that a granular material is filled between the outer crucible and the inner crucible.
In the method for growing an Fe—Ga based alloy single crystal of the present invention, the ratio of the outer diameter (φc) of the outer crucible to the outer diameter (φw) of the heating source is 0.4 <φc / φw <0 . 6 is preferable.
In the method for growing an Fe—Ga based alloy single crystal of the present invention, it is preferable to install a metal cylinder that is easily bonded to oxygen at the upper part of the crucible for the purpose of removing oxygen generated from oxygen and single crystal raw materials in the apparatus. .
In the method for growing an Fe—Ga based alloy single crystal according to the present invention, the metal is preferably titanium.

The apparatus for growing an Fe—Ga based alloy single crystal according to the present invention includes a double crucible composed of an outer crucible and an inner crucible arranged in the outer crucible, and a high frequency induction arranged outside the outer crucible. A seed crystal is brought into contact with a raw material melt in a crucible having a heating source, and then the seed crystal is pulled up to grow a single crystal.

In the Fe-Ga based alloy single crystal growth apparatus of the present invention, it is preferable that the outer crucible is a graphite crucible and the inner crucible is an alumina crucible.
Growing apparatus of Fe-Ga-based alloy single crystal of the present invention, it is preferable that the material of the inner crucible and the non-oxide ceramics.
Growing apparatus of Fe-Ga-based alloy single crystal of the present invention, the non-oxide ceramics, preferably a boron nitride.
In the Fe—Ga based alloy single crystal growth apparatus of the present invention, it is preferable to provide a spacer between the bottom surface of the outer crucible and the inner crucible.
In the apparatus for growing an Fe—Ga based alloy single crystal of the present invention, it is preferable that a granular material is filled between the outer crucible and the inner crucible.
In the apparatus for growing an Fe—Ga based alloy single crystal of the present invention, the ratio of the outer diameter (φc) of the outer crucible to the outer diameter (φw) of the heating source is 0.4 <φc / φw <0 . 6 is preferable.
The apparatus for growing an Fe—Ga based alloy single crystal of the present invention is preferably provided with a metal cylinder that is easily bonded to oxygen at the upper part of the crucible for the purpose of removing oxygen generated from oxygen in the apparatus and the raw material for the single crystal. .
In the Fe—Ga based alloy single crystal growth apparatus of the present invention, the metal is preferably titanium.

According to the present invention, the following effects can be obtained.
A large-scale Fe—Ga based alloy single crystal can be manufactured with good chemical composition and crystal orientation at low cost.
By using a carbon crucible outside the ceramic crucible made of alumina, an Fe—Ga single crystal can be produced by a high-frequency induction heating type Czochralski method.
Further, the Fe—Ga raw material itself also generates heat by high-frequency induction heating in accordance with the heating control of the carbon crucible, thereby enabling growth with low power.
By making the material of the crucible non-oxide ceramic (for example, boron nitride), it is possible to suppress the generation of floating substances such as Ga oxide and Ga—Al—O—C compound during single crystal growth, Single crystal growth is simplified, and it becomes easy to prevent crystal crystallization and cavitation due to suspended matter. In addition, by installing a cylinder made of metal (for example, titanium) that easily oxidizes,

It is a conceptual diagram which shows the single crystal growth apparatus which concerns on the 1st form for implementing this invention. It is a conceptual diagram which shows the single crystal growth apparatus which concerns on the 2nd form for implementing this invention. It is a conceptual diagram which shows the single crystal growth apparatus which concerns on the 3rd form for implementing this invention. It is a conceptual diagram which shows the single crystal growth apparatus based on the 4th form for implementing this invention. It is a conceptual diagram which shows the single-crystal growth apparatus based on the 5th form for implementing this invention. It is a conceptual diagram which shows the single crystal growth apparatus which concerns on a reference form. It is a conceptual diagram which shows the single-crystal growth apparatus based on the 6th form for implementing this invention. It is a conceptual diagram which shows the single crystal growth apparatus which concerns on a comparative example.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First form of training apparatus]
FIG. 1 is a diagram for explaining a single crystal pulling apparatus according to a first embodiment for carrying out the present invention.
The crucible is a double crucible composed of the outer crucible 19 and the inner crucible 18 disposed in the outer crucible 19. After the seed crystal 210 is brought into contact with the raw material melt 300 in the crucible, the seed crystal 210 is pulled up. This is a single crystal growing apparatus for growing a single crystal 200.
The side surface of the inner crucible 18 and the side surface of the outer crucible 19 may be disposed in contact with each other, or may be disposed apart from each other. When separated, a single crystal with less variation in composition and crystal orientation can be obtained. From such a viewpoint, the separation distance is preferably 1 mm to 10 mm, and more preferably 2 mm to 5 mm. Further, it is preferable to provide a spacer 21 between the bottom surface of the inner crucible 18 and the bottom inner surface of the outer crucible 19 as shown in FIG.
The crucible includes an inner crucible 18 made of alumina, and an outer crucible 19 made of graphite arranged at a distance from or outside the inner crucible 18.

This embodiment will be described in detail.
A heating chamber 15 formed of a heat insulating material provided in the chamber 11, a crucible provided in the heating chamber 15, and a heating coil 20 disposed on the outer periphery of the heating chamber 15, and heating the crucible After the seed crystal 210 is brought into contact with the raw material melt 300 obtained in this way, the seed crystal 210 is pulled up to grow the single crystal 200.
After bringing the seed crystal 210 into contact with the raw material melt 300 in the crucible, the seed crystal 210 is pulled up to grow the single crystal 200.
The crucible is an apparatus for growing a single crystal comprising an inner crucible 18 for holding a raw material and an outer crucible 19 arranged with or without a space outside the inner crucible 18.

Hereinafter, this embodiment will be described in more detail.
(Inner crucible)
The inner inner crucible 18 is made of a high melting point material. Alumina is preferred.
Further, magnesia or pietalite boron nitride (BN) may be used.

(Outside crucible)
The outer crucible 19 is made of graphite. Graphite is much cheaper than Ir. Moreover, the heat generation efficiency with respect to the high frequency (RF) is very good.
The outer crucible 19 has a bottom (bottomed) and a side wall that rises upward from the periphery of the bottom.

The height of the upper end (the uppermost portion of the side wall) of the outer crucible 19 is set not to be higher than the upper end of the inner crucible 18 so that carbon gas or carbon particles generated when graphite generates heat are not mixed into the melt. . In the example shown in FIG. 1, the upper ends of both are in a flush state.
The outer crucible 19 preferably has an outer diameter and an inner diameter appropriately set so that the entire outer surface of the inner crucible 18 and the entire inner surface of the outer crucible 19 are in contact with each other. Also at the bottom, it is preferable that the inner surface of the bottom of the outer crucible 19 is in contact with the outer surface of the bottom of the inner crucible 18 so that the inner crucible 18 can be slid into the outer crucible 19.
If the inner surface of the outer crucible 19 and the outer surface of the inner crucible 18 are mirror-finished, the inner crucible 18 can be easily slid into the outer crucible 19 and stored.
FIG. 1 shows an example in which the inner crucible 18 and the outer crucible 19 are arranged in contact with each other. However, when Fe is more than Fe0.80Ga0.20 or becomes higher due to a Ga substitute, carbon and Since alumina reacts, it is better to arrange the side wall of the inner crucible 18 and the side wall of the outer crucible 19 apart from each other.
In the embodiment shown in FIG. 1, the upper end of the outer crucible 19 is not higher than the upper end of the inner crucible 18.

[Second form of training apparatus]
FIG. 2 shows another form.
In this embodiment, a spacer 21 is provided between the outer bottom portion of the inner crucible 18 made of alumina and the inner bottom portion of the outer crucible 19. Further, the side walls are separated from each other.
In this embodiment, the inner crucible 18 is heated by radiant heat from the outer crucible 19 through the space between the side walls. Therefore, the temperature gradient in the melt 300 is further reduced, and a single crystal with less distortion is obtained.

  When the heater crucible is small (less than 8 inches), the melt heating side wall (heater crucible) is heated relatively uniformly and the natural convection of the melt is maintained. However, when the heater crucible becomes large (over 8 inches), the density of the high-frequency magnetic flux generated in the coil becomes weaker as it becomes the center of the heater crucible, creating a hot area where a part of the outer wall of the crucible is particularly heated, and the temperature gradient becomes tight. Become.

In order to weaken this phenomenon, the crucible that is not directly heated by the cushion is arranged inside rather than directly heating the melt by the heater crucible, so that the heating from the side is relatively weakened and the temperature distribution of the melt is reduced. The variation becomes mild and the temperature gradient does not become steep.
When the temperature gradient of the melt is relaxed, natural convection is stabilized and the effect of suppressing crystal defects and strains is produced.
Further, when the double structure is used, the life of each crucible can be increased.

  A tungsten spacer 21 is disposed on the bottom inner wall of the outer crucible 19, and the inner crucible 18 is placed on the spacer 21. In other words, heat is supplied by radiation at the side walls while being separated, but heat is provided by heat conduction at the bottom wall which is not directly supplied with power. Thereby, a temperature gradient can be decreased more.

[Third embodiment of the training apparatus]
FIG. 3 shows a growing apparatus according to the third embodiment.
A heating chamber formed of a heat insulating material 15 provided in the chamber 11, a crucible disposed inside the heating chamber, and a heating coil 20 disposed on the outer periphery of the heating chamber, and heating the crucible This is a single crystal growing apparatus for growing the single crystal 200 by bringing the seed crystal 210 into contact with the obtained raw material melt 300 and then pulling up the seed crystal 210.
The crucible includes a bottomed inner crucible 18 and a bottomed outer crucible 19 made of graphite disposed outside the inner crucible 18, and includes an outer periphery of the inner crucible 18 and an inner periphery of the outer crucible 19. In the space to be formed, tungsten carbide or alumina powder 350 is charged.
The inner crucible 18 is made of alumina, but the inner surface of the main body made of tungsten or tungsten alloy or molybdenum or molybdenum alloy may be covered with an alumina layer.

The training apparatus according to the present embodiment is created by the following procedure, for example.
(1) After the graphite crucible 19 which is an outer crucible is placed on a pedestal in the heating chamber, a powder 350 of an inorganic material such as alumina, tungsten carbide or alumina is preferably deposited on the bottom surface inside the graphite crucible 19 with a thickness of preferably 1 to 5 mm. Now lay down.
(2) The inner crucible 18 is placed on the tungsten carbide powder 350. At this time, the centers of the inner crucible 18 and the outer crucible 19 are matched.
(3) The outer shape of the inner crucible 18 is made smaller than the inner diameter of the graphite crucible (outer crucible) 19 by, for example, about 10 mm. If it does so, the clearance gap between the graphite crucible 19 and the inner crucible 18 will be 5 mm.
(4) Tungsten carbide or alumina powder is injected into the gap.
According to this embodiment, the following various effects are achieved.
Crystal growth is much cheaper and easier than coating with tungsten carbide. Tungsten carbide and alumina coatings are susceptible to cracking and deterioration when the number of use increases due to the difference in thermal expansion coefficient, but in the case of powder, the difference in thermal expansion can be absorbed.

In addition, by controlling the packing density, it is possible to control the amount and speed of heat transfer from the outer crucible 19 to the inner crucible 19, making it easy to set the optimal amount of transmission and transmission speed without causing a temperature gradient. It becomes possible.
The space between the inner crucible 18 and the outer crucible 19 may be filled with tungsten carbide powder or alumina powder, but a block-like W or WC spacer may be provided at the bottom of the inner crucible 18. By changing the size of the spacer, heat transfer from the outer crucible 18 to the inner crucible 19 can be controlled, and variations in the temperature distribution of the raw material melt can be further reduced.

[Fourth and fifth aspects of the breeding apparatus]
FIG. 4 shows a single crystal growth apparatus according to the fourth embodiment.
The raw material for a single crystal is formed in a double crucible (a crucible composed of a carbon crucible 2 as an outer crucible and an alumina ceramic crucible 3 as an inner crucible mounted therein) by a heating coil 4 for high frequency induction heating. Is an Fe—Ga single crystal production apparatus for producing an Fe—Ga single crystal by a melt-solidification method in which a molten crystal is heated and melted to pull up a grown crystal from a raw material melt. The single crystal raw material is placed in an alumina ceramic crucible 3. The carbon crucible 2 is heated by the high frequency induction heating coil 4 to melt the single crystal raw material.

In this embodiment, the inner crucible 3 is an alumina ceramic crucible.
A raw material for a single crystal in which Fe and Ga are weighed to a specified mol% is put in an alumina ceramic crucible 3, the alumina ceramic crucible 3 is installed in the carbon crucible 2, and an alumina refractory material 1 is installed for heat insulation. To do. The atmosphere in the furnace is replaced with an inert gas, and the output is gradually increased to a temperature at which the Fe—Ga raw material melts to heat the carbon crucible 2 and the Fe—Ga raw material. After that, using the cut single crystal as a seed crystal, lowering the rotated seed crystal to near the melt and raising the seed crystal while gradually lowering the temperature by bringing the tip of the seed crystal into contact with the melt To produce a single crystal.
In the manufacturing method using the high-frequency induction heating type Czochralski method, the ratio of the carbon crucible diameter (φc) to the heating coil diameter (φw) is preferably 0.4 <φc / φw <0.6. In this range, the power consumption is significantly reduced as compared to cases outside this range.

FIG. 5 shows an apparatus according to the fifth embodiment.
In this embodiment, in addition to the device structure according to the fourth embodiment, a cylinder forming a heating chamber is provided between the alumina refractory material 1 and the crucible. As a result, the temperature distribution of the melt becomes more uniform, and crystals with excellent uniformity can be obtained.

[ Sixth embodiment of the growing apparatus]
Hereinafter, the sixth embodiment will be described.
The suspended matter generated on the melt surface when growing the Fe—Ga based alloy single crystal is considered to be a Ga oxide, a Ga—Al—O—C compound, or the like. The suspended matter is considered to be a compound with oxygen generated from the heat insulating material in the furnace, the material of the crucible, and the raw material.
From the knowledge obtained, the present inventors
Maintain the pressure in the furnace at the time of growth in a reduced pressure state, and remove the generated oxygen.
The crucible used for the growth is made of a raw material, a heat insulating material, and a material made of boron nitride having no influence on the growth temperature.
Oxygen generated from raw materials is tied to a titanium cylinder installed in the device to reduce reaction with the melt.
Therefore, we can reduce the oxygen in the device and prevent the generation of Ga oxides, Ga-Al-O-C compounds, etc. It was found that the effect was obtained.

In order to grow an Fe—Ga based alloy single crystal using the technique of the present invention, an oxide single crystal growing apparatus by a general Czochralski method can be used.
The apparatus is provided with decompression means for decompressing the furnace body, pressure measurement means for monitoring decompression, temperature measurement means for measuring the furnace temperature, and means for supplying an inert gas into the furnace body. Above the device, a device for measuring the weight of the single crystal and a device for pulling up while rotating are provided.

In FIG. 6, the crystal growth apparatus includes a crucible formed of boron nitride and a crucible formed of carbon outside the crucible. A carbon heat insulating material disposed around the two types of crucibles, and a carbon Consists of a heater for heating.
At the top of the crucible, a titanium cylinder is attached to the heat insulating material.

In FIG. 7, there are a crucible formed of boron nitride and a crucible formed of carbon on the outside of the crucible, and is composed of a carbon heat insulating material disposed around two types of crucibles. There is a quartz cylinder outside the heat insulating material, and the outside of the cylinder is composed of a high frequency coil that functions as a heating device.
At the top of the crucible, a titanium cylinder is attached to the heat insulating material.

Crystals are manufactured as follows. First, a single crystal raw material is put into a boron nitride crucible, a carbon heater or a heating high-frequency coil is heated, and the raw material is melted to obtain a melt. When the raw material is sufficiently melted, a rod-like crystal processed with a single crystal as a seed crystal is brought into contact with the melt surface to start crystal growth. At this time, an inert gas is supplied into the furnace.
The growth of the single crystal, except for the above-mentioned conditions of the furnace configuration, adjusts the rotation speed and pulling speed of the seed crystal in accordance with a general method for producing an oxide single crystal, and the neck portion and shoulder portion of the crystal. Then, the straight body portion is formed. After the crystals are formed, the grown crystals are separated from the melt, and the heating source is gradually cooled to cool the crystals.

[Growth method]
<Preparation process>
In the preparation step, a seed crystal is prepared and attached to the holding member 13 of the pulling rod 12. Subsequently, the outer crucible 19 is arranged. A double-structure crucible is obtained by placing a spacer 21 made of a tungsten plate or an alumina plate on the bottom of the outer crucible 19 and providing an inner crucible 18 thereon.
Further, the raw material powder is filled in the inner crucible 18, and the carbon felt material 16 and the zirconia refractory 15 are assembled as a heat insulating container so as to surround the crucible in the chamber 11. Furthermore, a quartz tube 14 is disposed between the heating coil 20 and the heat insulating container 15. After the preparatory work is completed, the gas supply unit 22 is not supplied with a gas, and the inside of the chamber is decompressed using the exhaust unit 23.
Thereafter, argon gas is supplied from the gas supply unit 22 to bring the inside of the chamber 11 to normal pressure in an inert gas atmosphere. When supplying the gas, it is preferable to supply the gas so that the gas flows upward from below. Thereby, it can reduce that an impurity etc. mix in the melt 300. FIG.

<Melting process>
In the melting step, argon gas is supplied from the gas supply unit 22 to the chamber 11. The coil power supply supplies high-frequency electricity to the heating coil 20, magnetic flux is generated in the heating coil 20, and eddy current is generated in the graphite crucible 19 which is a heating element.
Since the melting point of the graphite crucible 19 is 3000 ° C., it is possible to heat the graphite crucible 19 to 2500 ° C. or higher, and the working efficiency increases when heated to 2500 ° C. or higher. However, the heating of the graphite crucible 19 is preferably 2500 ° C. or less, and more preferably 2300 ° C. or less. Thus, limiting the heating temperature of the graphite crucible 19 makes the life of the crucible much longer.

<Seeding process>
In the seeding step, the gas supply unit 22 supplies argon gas into the chamber 23.
The pulling drive unit lowers the pulling rod 12 to a position where the lower end of the seed crystal 200 attached to the holding member 13 comes into contact with the Fe—Ga raw material melt 300 in the inner crucible 18 to stop. In this state, the coil power supply adjusts the current value of the high-frequency current supplied to the heating coil 20 based on the weight signal from the weight detector.

<Shoulder formation process>
In the shoulder forming step, after the high frequency current supplied from the coil power supply to the heating coil 20 is adjusted, the material melt 300 is held for a while until the temperature of the raw material melt 300 is stabilized, and then the pulling rod 12 is moved at the first rotational speed. Pull up at the first pulling speed while rotating. Then, the seed crystal 210 is pulled up while being rotated while its lower end is immersed in the raw material melt 300, and a shoulder 220 that expands directly below the lead circle is formed at the lower end of the seed crystal 210. Will be formed.
The shoulder forming step is completed when the diameter of the shoulder 220 becomes several mm (1 to 5 mm) larger than the desired diameter of the substrate.

<Straight body part formation process>
In the straight body forming step, the gas supply unit 22 supplies argon gas into the chamber 11. The coil power supply continues to supply high-frequency current to the heating coil 20 to heat the raw material melt 300 through the inner crucible 18. The pulling drive unit pulls the pulling rod 12 at the second pulling speed. Here, the second pulling speed is different from the pulling speed for holding the raw material in the shoulder forming step. Further, the rotation drive unit rotates the pulling rod 12 at the second rotation speed.

Here, the second rotation speed is a speed different from the first rotation speed in the shoulder portion forming step.
Since the shoulder 220 integrated with the seed crystal 210 is pulled up while being rotated with its lower end immersed in the raw material melt 300, a cylindrical straight body portion is provided at the lower end of the shoulder 220. 230 is formed. The diameter of the straight body 230 may be several mm larger than the desired diameter of the substrate.

<Tail formation process>
The melt 300 is heated. Further, the pulling drive unit pulls the pulling rod 12 at the third pulling speed. Here, the third pulling speed is a speed different from the first pulling speed in the shoulder forming process or the second pulling speed in the straight body forming process.

In the tail formation step, the gas supply unit 22 supplies argon gas into the chamber 11.
Further, the coil power supply continues to supply a high frequency current to the heating coil 20 to heat the Fe—Ga melt 300 via the inner crucible 18. Further, the pulling drive unit pulls the pulling rod 12 at the third pulling speed. Here, the third pulling speed is a speed different from the first pulling speed in the shoulder forming process or the second pulling speed in the straight body forming process.
Furthermore, the rotation drive unit rotates the pulling rod 12 at the third rotation speed. Here, the third rotation speed is a speed different from the first rotation speed in the shoulder portion forming step or the second rotation speed in the straight body portion forming step. Note that, in the early stage of the tail formation process, the lower end of the tail 240 is kept in contact with the melt 300.
Then, at the end of the tail formation process after a predetermined time has elapsed, the pulling drive unit increases the pulling speed of the pulling rod 12 and pulls the pulling rod 12 upward further, thereby melting the lower end of the tail 240. Pull away from 300. Thereby, the Fe-Ga ingot 200 shown in FIG. 2 is obtained.

<Cooling process>
In the cooling process, the gas supply unit 22 supplies argon gas into the chamber 11. Further, the coil power supply stops the supply of high-frequency current to the heating coil 20 and stops the heating of the melt 300 via the crucible 17. Further, the pulling drive unit stops the pulling of the pulling rod 12, and the rotation driving unit stops the rotation of the pulling rod 12. At this time, a small amount of Fe—Ga that did not form the ingot 200 remains as the melt 300 in the crucible 17. For this reason, as the heating is stopped, the raw material melt 300 in the raw material holding crucible 18 is gradually cooled, and after solidifying below the melting point of the raw material, solidifies in the crucible 18 to become an Fe—Ga solid. Then, the Fe—Ga ingot 200 is taken out from the chamber 11 while the inside of the chamber 11 is sufficiently cooled.

  As described above, in the present embodiment, the inner crucible 18 is indirectly heated without directly heating the wall portion of the inner crucible 18 by the heating coil 20. For this reason, compared with the case where the wall part of the inner crucible 18 is directly heated with the heating coil 20, the temperature gradient of the melt in the crucible 17 can be relieved. Therefore, distortion generated in the single crystal grown by the rapid temperature gradient can be suppressed.

The crucible 419 generally has a circular opening as viewed from above, a cylindrical body, and a bottom surface having a planar shape, a bowl shape, or an inverted conical shape. Moreover, as a material for the crucible, a material that can withstand the melting point of Fe—Ga as a raw material melt and has low reactivity with Fe—Ga is suitable, and iridium, molybdenum, tungsten, rhenium, or a mixture thereof is generally used. Used.
The crucible 419 is supported by a cylindrical support base made of a refractory material.

  The single crystal pulling using the single crystal pulling apparatus described above is performed by putting the raw material into the crucible 419 and flowing the high frequency current through the heating coil 20 to heat the crucible 419 to melt the Fe—Ga raw material. The temperature is maintained by the heat retaining body 15, and the seed crystal 210 at the lower end of the pulling rod 12 is immersed in the melt 20 while rotating the pulling rod 12 or the crucible 419, and the pulling rod 12 is pulled up.

Example 1
An Fe—Ga—Sn alloy was grown using a high-frequency induction heating type Czochralski furnace.
A fine alumina crucible with an outer diameter of 45 mm is placed inside a graphite crucible with an inner diameter of 50 mm, and 400 g of a raw material containing 99.95% iron, 4N (99.99%) gallium and tin in a specified at% as starting materials. I put it in.

The crucible charged with the raw material was put into the growth furnace, the inside of the furnace was evacuated, argon gas was introduced, and when the inside of the furnace became atmospheric pressure, the heating of the apparatus was started, until the melt was reached, Heated for 12 hours. An iron gallium single crystal cut in the <001> direction was used as a seed crystal, and the seed crystal was lowered to near the melt.
The seed crystal is gradually lowered while rotating at 5 ppm, and the seed crystal is raised at a pulling speed of 1.0 mm / Hr while gradually lowering the temperature by bringing the tip of the seed crystal into contact with the melt. Crystal growth was performed.
As a result, a single crystal alloy having a diameter of 10 mm and a straight body portion length of 80 mm was obtained.

When this single crystal alloy was cut and polished into a wafer and the orientation was observed, the upper part was the (100) plane in the pulling direction and the (110) plane in the x and y directions perpendicular to the z direction. The Fe—Ga—Sn alloy was grown in the same orientation as that of the seed crystal used for pulling.
Similarly, in the middle part and the lower part, the crystal grew in a state where the same crystal orientation as that of the upper part was maintained.
The upper and lower Ga concentrations were approximately 16.0 at%, and the Sn concentration was approximately 2.0 at%. The Ga and Sn concentration difference was only about 1.0 at%.
The magnetostriction of the Fe—Ga alloy is sensitive to the crystal orientation and composition, and the largest magnetostriction occurs in the 100 direction, which is the easy axis of magnetization, when the Ga concentration is around 16.0 at% and the Sn concentration is around 2.0 at%. This single crystal alloy shows that it is a high-quality single crystal meeting this condition.

(Comparative example)
FIG. 8 shows a crystal growing apparatus using a single crucible.
Using this apparatus, the same growth as in the previous example was performed.
In this example, the variation in Ga concentration was larger than that in the example, and the crystal orientation was worse than that in the example.

(Example 2)
Single crystals were grown using the apparatus shown in FIG.
An FeGa single crystal was grown using a high-frequency induction heating type Czochralski furnace (CZ method).
700 g of raw material containing 80% Fe and 20% Ga as starting materials was charged into an alumina ceramic crucible with an inner diameter of 70 mm.
The crucible charged with the raw material was placed in the growth furnace, the inside of the furnace was replaced with argon gas, and flow was performed at a flow rate of 1.0 L / min. When the inside of the furnace became atmospheric pressure, the crucible was started to be heated gradually over 12 hours until reaching the melting point of FeGa. Thereafter, the single crystal cut in the (100) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 4.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 1.8 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 27 mm and a straight body portion length of 100 mm was obtained. This single crystal had good characteristics as in Example 1. It was a good crystal with no polycrystals and no cavities.

(Example 3)
A single crystal was grown using the apparatus shown in FIG.
An Fe—Ga single crystal was grown using a high-frequency induction heating type Czochralski furnace (CZ method).
200 g of raw material containing 80% Fe and 20% Ga as starting materials was charged into an alumina ceramic crucible having an inner diameter of Φ40 mm.
The crucible charged with the raw material was put into the growth furnace, the inside of the furnace was replaced with argon gas, and the flow was performed at a flow rate of 0.5 L / min. When the inside of the furnace became atmospheric pressure, the crucible was heated and gradually heated over 12 hours until reaching the melting point of Fe—Ga. Thereafter, the single crystal cut in the (110) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 12.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 1.8 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 25 mm and a straight body portion length of 50 mm was obtained. This single crystal had good characteristics as in Example 1. It was a good crystal with no polycrystals and no cavities.

Example 4
Single crystals were grown using the apparatus shown in FIG.
An FeGa single crystal was grown using a high-frequency induction heating type Czochralski furnace (CZ method).
As a starting material, an alumina ceramic crucible having an inner diameter of Φ100 mm was charged with 1.0 kg of a raw material containing 82% Fe and 18% Ga.
The crucible charged with the raw material was put into the growth furnace, the inside of the furnace was replaced with argon gas, and the flow was performed at a flow rate of 10.0 L / min. When the inside of the furnace became atmospheric pressure, the crucible was started to be heated gradually over 12 hours until reaching the melting point of FeGa. Thereafter, the single crystal cut in the (100) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 4.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 2.0 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 40 mm and a length of the straight body portion of 150 mm was obtained. This single crystal had good characteristics as in Example 1. It was a good crystal with no polycrystals and no cavities.

In this embodiment, the ratio between the outer diameter (φc) of the carbon crucible 2 and the outer diameter (φw) of the heating coil 4 as the heating source is changed by 0.1 in the range of 0.1-0.8. The power consumption was examined.
In the range of 1-0.8, the power consumption was very small compared to the other ranges.

(Example 5)
A Fe—Ga single crystal was grown using a resistance heating type Czochralski furnace (CZ method) shown in FIG.
700 g of a raw material containing 80% Fe and 20% Ga as starting materials was charged in a boron nitride crucible having an inner diameter of 70 mm. A crucible made of boron nitride charged with raw materials was placed in the growth furnace, the pressure in the furnace was reduced to a reduced pressure atmosphere, and argon gas was flowed at a flow rate of 1.0 L / min.
Thereafter, heating of the crucible was started and gradually heated over 12 hours until reaching the melting point of Fe—Ga. Thereafter, the single crystal cut in the (100) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 4.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 2.0 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 25 mm and a straight body portion length of 100 mm was obtained. There was almost no deterioration in quality due to oxides.

( Reference example)
An Fe—Ga single crystal was grown using a carbon heater- type Czochralski furnace (CZ method) shown in FIG.
200 g of a raw material containing 80% Fe and 20% Ga as starting materials was charged into a boron nitride crucible having an inner diameter of Φ40 mm. The crucible made of boron nitride charged with the raw material was put into the growth furnace, the pressure inside the quartz cylinder was reduced to a reduced pressure atmosphere, and argon gas was flowed at a flow rate of 0.5 L / min.
Thereafter, heating of the crucible was started and gradually heated over 12 hours until reaching the melting point of Fe—Ga. Thereafter, the single crystal cut in the (110) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 12.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 2.0 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 25 mm and a straight body portion length of 50 mm was obtained. There was almost no deterioration in quality due to oxides.

(Example 6 )
An Fe—Ga single crystal was grown using a high-frequency induction heating type Czochralski furnace (CZ method) shown in FIG.
As a starting material, 1.0 kg of a raw material containing 82% Fe and 18% Ga was added to a boron nitride crucible having an inner diameter of Φ100 mm. The crucible made of boron nitride charged with the raw material was put into the growth furnace, the pressure in the quartz cylinder was set to a reduced pressure atmosphere, and argon gas was flowed at a flow rate of 1.0 L / min.
Thereafter, heating of the crucible was started and gradually heated over 12 hours until reaching the melting point of Fe—Ga. Thereafter, the single crystal cut in the (110) orientation was used as a seed crystal, and the seed crystal was lowered to near the melt. The seed crystal is gradually lowered while rotating at a speed of 4.0 revolutions per minute, and the tip of the seed crystal is brought into contact with the melt and the temperature is gradually lowered, while the effective growth is performed at a speed of 2.0 mm / h. Crystal growth was carried out by raising the seed crystal.
As a result, a single crystal having a diameter of 40 mm and a length of the straight body portion of 150 mm was obtained. There was almost no deterioration in quality due to oxides.

1 Refractory material made of porous alumina 2 Carbon crucible (crucible)
3 Alumina ceramic crucible (crucible)
4 Heating source (heating coil)
11 Chamber 12 Pulling rod 13 Holding member 14 Quartz tube 15 Heating chamber 16 Carbon felt 17 Inner crucible 18 Inner crucible 19 Outer crucible 20 Heating means (heating coil)
21 Spacer 22 Gas supply part 23 Gas exhaust part 200 Ingot (single crystal)
210 Seed crystal 220 Shoulder 230 Straight body 240 Tail 300 Raw material melt 350 Powder of inorganic material (tungsten carbide)

Claims (18)

The crucible is a double crucible composed of an outer crucible and an inner crucible arranged in the outer crucible, heated by a high frequency induction heating source arranged outside the outer crucible, and a raw material melt in the inner crucible A method for growing an Fe—Ga-based alloy single crystal in which a seed crystal is brought into contact with the seed crystal and then the seed crystal is pulled up to grow a single crystal. The method for growing an Fe-Ga based alloy single crystal according to claim 1, wherein the outer crucible is a graphite crucible, and the inner crucible is an alumina crucible. The method for growing an Fe—Ga based alloy single crystal according to claim 1, wherein a material of the inner crucible is a non-oxide ceramic. The method for growing an Fe—Ga based alloy single crystal according to claim 3, wherein the non-oxide ceramic is boron nitride. The method for growing an Fe—Ga based alloy single crystal according to claim 1, wherein a spacer is provided between a bottom surface of the outer crucible and the inner crucible. The method for growing an Fe-Ga based alloy single crystal according to any one of claims 1 to 5, wherein a granular material is filled between the outer crucible and the inner crucible. The Fe- according to any one of claims 1 to 6, wherein a ratio of an outer diameter (φc) of the outer crucible and an outer diameter (φw) of the heating source is 0.4 <φc / φw <0.6. A method for growing a Ga-based alloy single crystal. The method for growing a single crystal according to any one of claims 1 to 7, wherein a metal cylinder that is easily bonded to oxygen is installed on the upper part of the crucible for the purpose of removing oxygen in the apparatus and oxygen generated from the raw material for single crystal. The method for growing an Fe—Ga based alloy single crystal according to claim 8, wherein the metal is titanium. A seed crystal is formed in a raw material melt in a crucible having a crucible having a double crucible including an outer crucible, an inner crucible disposed in the outer crucible, and a high-frequency induction heating source disposed outside the outer crucible. A Fe-Ga based alloy single crystal growth apparatus for raising a seed crystal by bringing the seed crystal up after contact. The method for growing an Fe-Ga based alloy single crystal according to claim 10, wherein the outer crucible is a graphite crucible and the inner crucible is an alumina crucible. The apparatus for growing an Fe-Ga based alloy single crystal according to claim 10, wherein a material of the inner crucible is a non-oxide ceramic. The apparatus for growing an Fe—Ga based alloy single crystal according to claim 12, wherein the non-oxide ceramic is boron nitride. The apparatus for growing an Fe-Ga based alloy single crystal according to any one of claims 10 to 13, wherein a spacer is provided between a bottom surface of the outer crucible and the inner crucible. The Fe-Ga-based alloy single crystal growing apparatus according to any one of claims 10 to 14, wherein a granular material is filled between the outer crucible and the inner crucible. The Fe- according to any one of claims 10 to 15, wherein a ratio of an outer diameter (φc) of the outer crucible and an outer diameter (φw) of the heating source is 0.4 <φc / φw <0.6. An apparatus for growing a Ga-based alloy single crystal. 17. The apparatus for growing a single crystal according to any one of claims 10 to 16, wherein a metal cylinder that is easily bonded to oxygen is installed on the upper part of the crucible for the purpose of removing oxygen in the apparatus and oxygen generated from the raw material for single crystal. The apparatus for growing an Fe-Ga based alloy single crystal according to claim 17, wherein the metal is titanium.

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