KR102136320B1 - Crystal Growth Apparatus and Forming Method for SiC Single Crystal using the Same - Google Patents

Abstract

The present invention relates to an apparatus for forming a silicon carbide single crystal, wherein the crucible and the seed crystal are fixed, and the introduction into the crucible includes an immersion portion, and the immersion portion is configured to fix the rest of the seed crystal except for the upper and lower portions. There is provided a crystal forming apparatus that induces the first crystal growth at the top and the second crystal growth at the bottom, with the top and bottom of the seed crystals respectively contacting the melt, with this being introduced into the crucible.

Description

Crystal forming apparatus and silicon carbide single crystal formation method using same {Crystal Growth Apparatus and Forming Method for SiC Single Crystal using the Same}

The present invention relates to a crystal forming apparatus and a method of forming a silicon carbide single crystal using the same.

Silicon carbide (SiC) single crystal is widely used as a component material in the semiconductor, electronic, automotive, and mechanical fields due to its excellent mechanical strength such as wear resistance, heat resistance, and corrosion resistance.

For growth of silicon carbide single crystals, for example, the Achison method of reacting carbon and silica in a high temperature electric furnace of 2000 degrees (°C) or higher, and using silicon carbide as a raw material to sublimate at a high temperature of 2000 degrees (℃) or higher to obtain a single crystal. There are a sublimation method for growing, a solution growth method using a crystal pulling method, and the like. In addition, chemical vapor deposition methods using gas sources have been used.

However, the Achison method is very difficult to obtain a high-purity silicon carbide single crystal, and the chemical vapor deposition method can grow only to a limited thickness with a thin film. Accordingly, research has been focused on a sublimation method of sublimating silicon carbide at high temperatures to grow crystals. However, the sublimation method is also generally performed at a high temperature of 2400°C or higher, and there is a possibility that various defects such as micro-pipes and lamination defects are likely to occur, thereby limiting production cost.

The present invention aims to solve the problems of the prior art as described above and the technical problems requested from the past.

Specifically, the object of the present invention is to allow crystal growth at the top and bottom of the seed crystals, thereby reducing the time required for crystal growth, while providing a crystal forming apparatus capable of obtaining high-purity silicon carbide single crystals with few defects. Is to provide.

Crystal forming apparatus according to the present invention for achieving this object,

A crystal forming apparatus for growing at least one silicon carbide (SiC) seed crystal into a silicon carbide (SiC) single crystal while immersed in a melt containing silicon and carbon,

A crucible filled with the melt; And

And an immersion portion configured to be introduced into the crucible with the seed crystal fixed.

The immersion unit,

It is configured to mechanically fix the rest of the seeds except for the upper and lower portions of the seed crystals partitioned based on an imaginary axis parallel to the ground;

In the state introduced into the crucible, the upper and lower portions of the seed crystals are respectively contacted with a melt to induce first crystal growth at the top and second crystal growth at the bottom.

That is, the crystal forming apparatus according to the present invention is characterized by a structure for fixing the top and bottom of the seed crystal to be exposed, and based on this structure, the first crystal growth and the second crystal growth at the top and bottom of the seed crystal respectively. By being induced, a faster rate of crystal growth of seed crystals can be expected.

The crystal forming apparatus according to the present invention also expresses a special effect capable of obtaining a high-purity single crystal with few defects at the top of the seed crystal, and the detailed structure for achieving this is described in detail below through non-limiting examples of the present invention. As described.

In one specific example, the immersion portion,

A shaft part configured to move along an up and down axis and rotate about the axis; And

A crystal growth part coupled to a lower end of the shaft part in a detachable form, including at least one fixing member, and in which a seed crystal is sandwiched in at least a part of an inner surface of the fixing member;

It may include.

Here, among the front surfaces of the seed crystals exposed in a state fixed to the fixing member, the upper and lower portions of the seed crystals are divided based on an imaginary axis parallel to the ground;

When the shaft part rotates axially, the first crystal growth and the second crystal growth can be induced independently, while the flow of the melt flowing along the crystal growth portion is in contact with the upper front and lower front surfaces of the seed crystal, respectively.

That is, in the present invention, the upper part of the seed crystal means a front surface of a crystal positioned at an upper side relative to an imaginary axis parallel to the ground even in a seed crystal that may include a plurality of crystal faces, and in particular, the seed crystal is fixed. Refers to all the crystal faces of the seed crystal that are exposed upward through the fixing member among the upper parts while attached to the member.

Likewise, in the present invention, the lower portion of the seed crystal means a crystal front surface located at a lower side relative to an imaginary axis parallel to the ground, and more specifically, the seed crystal which may include a plurality of crystal faces, and more specifically, the seed crystal. In the state attached to this fixing member, it means the entire crystal faces of the seed crystals exposed downward through the fixing member, among the lower parts.

Therefore, even in the form of a seed crystal including a plurality of crystal faces extending irregularly, when using the crystal forming apparatus according to the present invention, crystal growth can be induced across the crystal faces constituting the top and bottom of the seed crystal respectively. I can fully understand that there is.

Crystal growth generally occurs gradually as the melt solidifies at a relatively large surface area, and for this purpose, the seed crystal can be plate-shaped to have a large surface area, and in the form of a fixing member, for example circular, polygonal , It may have a variety of planar shapes corresponding to the structure such as irregular.

Thus, the fixing member of the present invention, when fixing the seed crystals of the shape, configured to fix the rest of the portion except for the top and bottom, the entire crystal surface of the top and bottom of the seed crystal is exposed and contacted with the molten solution as it is, thereby Thus, crystal growth can be induced in each of the upper and lower portions. This shows that the crystal growth into a single crystal is remarkably fast compared to an apparatus in which crystal growth is performed on the deflected one side of the seed crystal.

For example, in the case of adding an adhesive to the top of the seed crystal for fixing the seed crystal or inserting a shaft by processing the crystal surface on the top, the crystal growth is not completely performed due to the adhesive or the shaft located on the top of the seed crystal. , Since the present invention is completely exposed to the melt as well as the lower portion of the seed crystal, it is possible to induce crystal growth in both upper and lower portions.

The fixed shape of the seed crystal for achieving this is due to the shape of the fixed member according to the present invention, and specifically, the fixed member is an open structure such that both the upper and lower portions of the seed crystal are exposed, and in one example, the fixed member Is a circular ring made of a graphite material, and may be a method in which the seed crystals are fitted and fixed to the inner surface of the circular ring.

In another example, the fixing member has a structure in which a plurality of supports spaced apart from each other at a predetermined interval and parallel to the ground extend in a central direction from the inner surface of the circular ring;

The seed crystal may be a structure that is fixed by being fitted to the inner surface of the end of the support.

In such a structure, when the shaft is axially rotated, the supports may stir the melt, thereby inducing rapid convection of the melt, resulting in rapid crystal growth.

Unlike this, the fixing member,

A plurality of supports parallel to the ground and spaced apart from each other at predetermined intervals extend in a central direction from the inner surface of the circular first ring, and a second ring connecting the ends of the supports circularly to the ends It is a connected structure;

The seed crystal is clamped and fixed to the inner surface of the second ring;

When the shaft is axially rotated, the supports may be configured to stir the melt.

The fixing member may be a combination of one or two or more to form a crystal growth portion, and in the case of two or more, the fixing members are arranged to be spaced apart at predetermined intervals, and seed crystals are fixed to each fixing member, thereby allowing a plurality of species The structure of crystal growth of crystals into single crystals may also be implemented under the scope of the present invention.

All of the above fixing members are made of a structure including a circular ring, but in some cases, for fixing a thin seed crystal, a fixing member having grooves such as grooves may be considered.

In a specific example of this, the crystal forming apparatus, as a fixing member, may include at least two or more cylindrical fixing members with grooves formed along its outer circumference, such that at least a part of the seed crystal is inserted, and the fixing member They may be connected to the shaft portion in a state arranged to be spaced apart from each other on a line parallel to the ground. The crystal forming apparatus having such a structure can fix the seed crystal in a form in which the seed crystal is inserted into the groove of the fixing members.

The crystal growth portion including the fixing members may further include a connecting portion coupled to the shaft portion, and a plurality of rod-like fastening members coupled to each of the connecting portion and the fixing member.

In this structure, when the shaft is axially rotated, fluid resistance is formed in the fastening members, and the flow rate of the melt contacting the upper portion may be 10% to 80% compared to the flow rate of the melt contacting the lower part.

That is, the flow of the melt flowing through the upper portion of the seed crystal has a low flow rate by the fastening members, and thus, the crystal growth at the top proceeds rather slowly, but the step due to the gradual crystal growth is relatively wide, but the number of steps It may be formed less, and the thickness may be relatively thin, and within a crystal step, the probability that an empty space is formed is significantly low. In other words, a very smooth crystal surface may be formed on the top of the seed crystal, which is defined as the first crystal growth in the present invention.

In addition, the connecting portion and the fixing member have an arrangement form facing each other, whereby, the melt flowing through the upper portion of the seed crystal can flow at a relatively constant flow rate in a space set between the connecting portion and the fixing member. It is a major advantage that drives gradual crystal growth on top of seed crystals.

In order to adjust the flow rate of the molten liquid formed between the connecting portion and the fixing member, the length of the fastening members may be configured in a desired shape, and the number of fastening members may also be adjusted to increase or decrease the flow rate of the molten liquid. It can be composed of.

On the other hand, since the flow rate of the molten liquid is relatively fast at the bottom of the seed crystal, the crystal growth is gradual, but the speed is fast compared to the top, and the step is relatively narrow and the number of steps is formed, so that the thickness may be relatively thick. have. That is, crystal growth may proceed fairly rapidly at the bottom of the seed crystal, which is referred to as second crystal growth in the present invention.

In summary, the first crystal growth at the top forms a relatively thin first crystal thickness and a relatively wide first crystal step;

The growth of the second crystal at the lower portion where the flow rate of the molten liquid is faster than the upper portion may form a second crystal thickness that is relatively thicker than the first crystal thickness and a second crystal step that is relatively narrower than the first crystal level. have.

On the other hand, in the present invention, the shaft portion is configured to substantially rotate the crystal growth portion to convect the melt around the crystal growth portion. As a result, the rotational speed of the shaft portion can also be regarded as a factor affecting crystal growth. will be.

If the shaft rotational speed of the shaft portion is excessively fast, the flow rate of the melt flowing through the upper and lower portions of the seed crystals is also fast, and it is difficult to form a smooth crystal surface while crystal growth occurs at a deflected region, and conversely, the shaft rotational speed of the shaft portion When is excessively slow, crystal growth may not be achieved at a desired thickness.

Thus, according to what the inventors of the present invention have confirmed, when the shaft rotational speed per minute of the shaft portion is 3 rpm to 60 rpm, it was confirmed that a desired level of crystal growth was achieved, and specifically, the shaft portion at 5 rpm to 40 rpm. The axial rotational speed can be selected variable or constant.

In the present invention, the melt may further include a metal melt, and the metal may be, for example, chromium, aluminum, titanium, etc., but is not limited thereto.

The present invention also provides a method for obtaining a silicon carbide single crystal using the above crystal forming apparatus.

Specifically, the method includes the steps of mounting a seed crystal in a crystal generating part of an immersion part and preparing a melt in a crucible;

Descending the shaft portion of the immersion portion to immerse the seed crystal in the melt; And

A process of inducing a first crystal growth at the top and a second crystal growth at the bottom by forming a flow of the melt on each of the upper and lower portions of the seed crystal by rotating the shaft portion axially;

It may include.

As described above, the crystal forming apparatus according to the present invention, by inducing the first crystal growth and the second crystal growth at the top and bottom of the seed crystal, respectively, it is possible to obtain a single crystal faster, in particular, the first crystal growth It is possible to form a smooth crystal surface, and in the second crystal growth, it is possible to achieve a crystalline form of a thick thickness, it is possible to manufacture a good product while also having the advantage of excellent manufacturing processability.

1 is a schematic view of a crystal forming apparatus according to an embodiment of the present invention;
2 is a perspective view of the crystal generation unit;
3 is a vertical sectional view of a shape in which a seed crystal is fixed to a fixing member;
4 is an enlarged photograph of a single crystal obtained using the crystal forming apparatus shown in FIGS. 1 to 3;
5 is a schematic view of a crystal forming apparatus according to another embodiment of the present invention;
6 is a plan view schematically showing a fixing member in the configuration of FIG. 5;
7 is a plan view schematically showing a fixing member according to another embodiment;
8 is a schematic view of a crystal growth unit including fixing members according to another embodiment;
9 is an enlarged view of the fixing member of FIG. 8.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the present description, descriptions of already known functions or configurations will be omitted to clarify the gist of the present description.

In order to clearly describe the description, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification. In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, and thus the description is not necessarily limited to what is illustrated.

1 is a schematic plan view of a crystal forming apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view illustrating a crystal generating unit of FIG. 1.

Referring to these drawings together, the crystal forming apparatus 100 includes an immersion unit 110 configured to be introduced into the crucible 120 in a state where the crucible 120 and the seed crystal 20 filled with the melt 10 are fixed. ).

The crucible 120 may be made of graphite, and in some cases, a heating member (not shown) may be additionally provided on the inner surface.

The immersion unit 110 includes a shaft portion 300 and a crystal growth portion 200 configured to move along the upper and lower axes Y and rotate relative to the axis Y. As an example, the shaft portion 300 may be made of graphite, and the crystal growth portion 200 may also be made of graphite.

The crystal growth unit 200 is coupled to each of these between the connecting portion 220, the fixing member 230, and the connecting portion 220 and the fixing member 230, which are coupled in a detachable form to the lower end of the shaft portion 300. It includes a plurality of rod-shaped fastening members 240.

The fixing member 230, as shown in the figure, is in the form of an O-ring with a structure in which both the upper and lower parts are open, and consists of a circular ring made of graphite.

In addition, as shown in FIG. 2, an elastic member 250 such as rubber or polymer resin may be added to the open inner surface of the circular ring to enable elastic mounting when the seed crystal is mounted.

In this case, the elastic member 250 may substantially form the inner surface of the fixing member 230. However, this is one embodiment, and the structure in which the elastic member is not added to the open inner surface of the circular ring is also incorporated as the embodiment according to this embodiment.

The seed crystal 20 is fixed by being fitted so as to be in close contact with the inner surface of the circular ring, and when the seed crystal 20 is fixed as described above, the shaft portion 300 moves as shown in FIG. 1 to move the seed crystal 20 together. The crystal production section is immersed in the melt 10.

Here, among the front surfaces of the seed crystals 20 exposed through the upper and lower surfaces of the open ring, the upper part of the seed crystals 20 based on the imaginary axis A-A' parallel to the ground X (1) and the lower part (2) are divided.

This will be described in detail with reference to the form in which the seed crystal is fixed to the fixing member 230 shown in FIG. 3.

In the present invention, the upper part 1 of the seed crystal 20 is positioned at the upper side relative to the imaginary axis A-A' parallel to the ground even in the seed crystal 20, which may include a plurality of crystal faces. Means the entire surface of the crystal, and, in detail, the seed crystal 20 is mounted upwardly through the open portion of the fixing member 230 among the upper part while the seed crystal 20 is mounted on the fixing member 230. It means the whole decision plane.

Likewise, in the present invention, the lower 2 of the seed crystal 20 is located on the lower 2 side relative to an imaginary axis parallel to the ground in the seed crystal 20, which may include a plurality of crystal faces. Means the entire surface, and more specifically, the seed crystal 20 is exposed downward through the open part of the fixing member 230 among the upper part in the state in which the seed crystal 20 is mounted on the fixing member 230 It means the whole decision side.

Referring back to FIGS. 1 and 2, as the shaft part 300 rotates axially, the flow of the melt 10 flowing around the crystal growth part 200 flows upward and downward (2) of the seed crystal 20. ) Respectively, the first crystal growth in the upper (1) and the second crystal growth in the lower (2) is induced.

However, when the shaft portion 300 is axially rotated, fluid resistance is formed by the fastening members 240, and the flow of the melt 10 flowing in the upper portion 1 of the seed crystal 20 is slowed. In addition, the connecting portion 220 and the fixing member 230 have an arrangement form facing each other, so that the molten liquid 10 flowing over the seed crystal 20 has a space set between the connecting portion 220 and the fixing member 230 ( 260) to flow at a relatively constant flow rate.

That is, the flow of the melt 10 flowing through the upper portion 1 of the seed crystal 20 has a low flow rate and a constant flow rate by the fastening members 240, and thus, the crystal growth in the upper portion 1 is somewhat Although it progresses slowly, the step due to the gradual crystal growth is relatively wide, but the number of steps is small and the thickness may be relatively thin, and the probability that an empty space ('defect') is formed in the step is significantly low. In summary, a very smooth crystal surface can be formed at the top 1 of the seed crystal 20, which is the growth of the first crystal above.

On the other hand, since there is no acting as a resistance to the flow of the melt 10 in the lower part 2 of the seed crystal 20, the flow rate of the melt 10 is relatively high and the melt 10 is brought into contact with the seed crystal 20. Although the flow rate of is not constant, the crystal growth is gradual, but the speed is fast compared to the upper part (1).

In addition, although the width of the step is relatively narrow, and a number of steps are formed, the total thickness of the crystal grown in the lower portion 2 of the seed crystal 20 is relatively thick.

In summary, crystal growth can proceed fairly rapidly in the lower portion 2 of the seed crystal 20, which is the second crystal growth above.

In this regard, using the crystal forming apparatus shown in FIGS. 1 to 3, under the following conditions, seed crystals were grown by crystal to obtain silicon carbide single crystals, and an actual picture of the silicon carbide is shown in FIG. 4.

-The melt contained 40 at% chromium and carbon and silicon, and the temperature of the melt was maintained at about 1900 degrees (°C), and the shaft portion was rotated 5 times per minute.

As can be seen in FIG. 4, when using the crystal forming apparatus according to the present invention, it can be seen that the first crystal growth and the second crystal growth were induced at the top and bottom of the seed crystal, respectively, and the silicon carbide was different at the top and bottom, respectively. It can be seen that it has a crystal plane.

In addition, it can be seen that the step shape at the top where the first crystal growth was induced has a relatively large area and a relatively small number of steps as compared to the bottom, and thus it can be visually confirmed that the step shape is smooth. This is based on the special structure of the crystal growth section described above. In addition, it can be confirmed that there is no difference in brightness across the entire crystal plane when transmitted from the upper portion where the first crystal growth is induced, which means that no empty space is formed in the crystal.

On the other hand, the step shape at the bottom where the second crystal growth is induced, the number of steps is relatively large compared to the top, it can be seen that the area is relatively narrow, that is, it can be seen that the crystal growth is formed relatively thick. .

As described above, the crystal forming apparatus according to the present invention may take a relatively short time to obtain a silicon carbide of a desired thickness, and nevertheless, in the first crystal growth, the surface is smooth to obtain high quality silicon carbide. In the second crystal growth, it is possible to obtain a crystalline form of a thick silicon carbide, thereby achieving both purposes of quality and crystal amount. It should be noted that this is a new method and result that did not exist in the past.

Meanwhile, FIG. 5 schematically shows a crystal forming apparatus according to another embodiment of the present invention, and FIG. 6 shows a schematic plan view of the fixing member in FIG. 5.

The crystal forming apparatus 400 according to FIG. 5 is similar to the structure in FIGS. 1 to 3, but the fixing member 410 is made of a different structure.

5 and 6, a plurality of supports 420 in which the fixing member 410 is parallel to the ground and spaced from each other at a predetermined interval is centered from the inner surface of the circular first ring 411. A second ring 412 extending in the direction and circularly connecting the ends of the supports 420 is configured to be connected to the ends 420.

Here, the seed crystal 20 is fixed by being fitted to the inner surface of the second ring 412, and when the shaft portion 300 is axially rotated, the second ring 412 and the first ring 411 are connected to each other The support 420 to agitate the melt 10.

Accordingly, in the crystal forming apparatus according to FIG. 5, the supports 420 may induce rapid convection of the melt 10 and consequently induce rapid crystal growth.

In addition, a space 430 is formed between adjacent supports 420, and the sizes of the spaces 430, for example, areas on a plane, may all be the same. This allows a certain amount of the melt 10 to flow while staying on the upper spaces 430, thereby imparting some sort of regularity to the flow of the melt 10 convecting under the seed crystal 20, thereby making the seed crystal 20 ), it is possible to suppress the phenomenon of indiscriminate crystal growth.

As in the description of FIGS. 1 to 3, the crystal forming apparatus according to the present embodiment is, of course, configured to induce first and second crystal growth at the top and bottom of the seed crystal, respectively, and the advantages therefrom Will also be the same.

7 shows a fixing member having a different structure from the above fixing member structure.

Referring to FIG. 7, the fixing member 510 has a structure in which a plurality of supports 520 spaced apart from each other at a predetermined interval and parallel to the ground extend in the center direction from the inner surface of the circular ring 512. consist of.

Here, the seed crystal 20 is fixed by being fitted to the inner end surface of the supports 520, and when the shaft portion 300 is axially rotated, the supports 520 can stir the melt 10.

As in FIG. 5, by the supports 520, a kind of regularity may be imparted to the flow of the melt 10 convected under the seed crystal 20, thus indiscriminate crystal growth on the seed crystal 20. This can be suppressed.

FIG. 8 is a schematic view of a crystal growth portion including another type of fixing members, and FIG. 9 is an enlarged view of the fixing member of FIG. 8.

Referring to FIGS. 8 and 9 together, the crystal growth part 600 is spaced apart at a predetermined distance from the lower end of the connecting part 610 and the connecting part 610 that are coupled in a detachable form to the lower end of the shaft part (not shown). It includes a plurality of rod-shaped fastening members 620 that are coupled and fixed members 630 connected to each of the rod-shaped fastening members 610.

Each of the fixing members 630 is formed in a cylindrical shape with a groove 640 along its outer circumference so that at least a portion of the seed crystal 20 is inserted. Here, the fixing members 630 are spaced apart from each other on a line parallel to the ground while being coupled to the lower ends of the rod-like fastening members 620 spaced apart at predetermined intervals, respectively.

In this structure, the seed crystal 20 is fixed to the crystal growth portion while being inserted into all the grooves 640 of the fixing members 630.

In the foregoing, although specific embodiments of the present invention have been described and illustrated, the present invention is not limited to the described embodiments, and it is common knowledge in the art that various modifications and modifications can be made without departing from the spirit and scope of the present invention. It is obvious to those who have it. Therefore, such modifications or variations should not be individually understood from the technical spirit or viewpoint of the present invention, and the modified embodiments should belong to the claims of the present invention.

100: crystal forming device
20: seed crystal
10: melt
300: shaft part
200: immersion

Claims (11)

A crystal forming apparatus for growing at least one silicon carbide (SiC) seed crystal into a silicon carbide (SiC) single crystal while immersed in a melt containing silicon and carbon,
A crucible filled with the melt; And
And an immersion portion configured to be introduced into the crucible with the seed crystal fixed.
The immersion portion,
A shaft portion configured to move along a first axis and rotate relative to the first axis, and
It includes a crystal growth portion for immersing the seed crystal in the melt,
The crystal growth portion includes a connecting portion and a fixing member,
It is configured to mechanically fix the remaining portions except for the upper and lower portions of the seed crystals partitioned on the second axis parallel to the ground on at least a part of the inner surface of the fixing member, and the second axis is perpendicular to the first axis. ,
In the state introduced into the crucible, the upper portion of the seed crystal is brought into contact with the molten liquid flowing in the space between the connecting portion and the fixing member, so that the first crystal growth is induced, and the lower portion of the seed crystal is brought into contact with the molten liquid flowing in the crucible. Second crystal growth is induced,
A crystal forming apparatus having a different crystalline form between the upper portion where the first crystal growth is induced and the lower portion where the second crystal growth is induced. The crystal forming apparatus according to claim 1, wherein the connecting portion is connected in a detachable form to a lower end of the shaft portion. According to claim 2,
Among the front faces of the seed crystals exposed in a state fixed to the fixing member, the upper and lower portions of the seed crystals are divided based on the second axis parallel to the ground;
When the shaft is axially rotated, while the flow of the molten liquid flowing along the crystal growth portion is in contact with the upper and lower front surfaces of the seed crystal, respectively, the first crystal growth and the second crystal growth are independently induced crystal formation Device. According to claim 3,
The crystal growth portion further includes a plurality of rod-shaped fastening members coupled to each of these between the connecting portion and the fixing member;
When the shaft is axially rotated, while the fluid resistance is formed in the fastening members, the flow rate of the melt contacting the upper portion is 10% to 80% compared to the flow rate of the melt contacting the lower part. The method of claim 4,
The first crystal growth at the top has a crystalline form forming a first crystal thickness and a first crystal step;
The second crystal growth in the lower portion where the flow rate of the melt is faster than the upper portion is a crystal having a second crystal thickness thicker than the first crystal thickness and a crystal form forming a second crystal step narrower than the first crystal step Shaping device. The crystal forming apparatus according to claim 2, wherein the fixing member is a circular ring made of graphite, and the seed crystals are fitted and fixed to the inner surface of the circular ring. According to claim 2, The fixing member is a structure spaced apart from each other at a predetermined interval and parallel to the ground a plurality of supports extending from the inner surface of the circular ring to the center direction;
The seed crystals are fitted and fixed to the inner surfaces of the ends of the supports;
When the shaft is axially rotated, the support is a crystal forming apparatus for stirring the melt. According to claim 2, The fixing member,
A plurality of supports parallel to the ground and spaced apart from each other at predetermined intervals extend in a central direction from the inner surface of the circular first ring, and a second ring connecting the ends of the supports circularly to the ends It is a connected structure;
The seed crystal is clamped and fixed to the inner surface of the second ring;
When the shaft is axially rotated, the support is a crystal forming apparatus for stirring the melt. According to claim 2,
At least two cylindrical fixing members having grooves formed along its outer circumference so that at least a portion of the seed crystal is inserted;
The fixing members are connected to the shaft part in a state arranged to be spaced apart on a line parallel to the ground;
A crystal forming apparatus for fixing a seed crystal in the form in which the seed crystal is inserted into a groove of the fixing members. The crystal forming apparatus according to claim 2, wherein the shaft rotational speed per minute of the shaft portion is 3 rpm to 60 rpm. The crystal forming apparatus according to claim 1, wherein the melt further comprises a metal melt.

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