KR102553771B1 - Manufacturing apparatus for silicon carbide single crystal and manufacturing method of silicon carbide single crystal - Google Patents

Abstract

An apparatus for manufacturing a silicon carbide single crystal according to an embodiment of the present invention includes a chamber, a crucible located in the chamber, a seed crystal moving into the crucible, a heating unit located on the outer circumferential surface of the crucible, and a raw material supply unit located in the chamber. The raw material supply unit includes a first container into which the raw material is charged, and an inlet pipe connected to the first container and through which the raw material moves, and a part of the inlet pipe overlaps the heating unit.

Description

Manufacturing apparatus and manufacturing method of silicon carbide single crystal

The present invention relates to an apparatus for manufacturing a single crystal of silicon carbide and a method for manufacturing a single crystal of silicon carbide.

Silicon carbide (SiC) single crystal has excellent mechanical strength such as wear resistance, heat resistance, and corrosion resistance, and is widely used as a component material in semiconductors, electronics, automobiles, and machinery fields.

For the growth of silicon carbide single crystal, for example, the Acheson method in which carbon and silica are reacted in a high-temperature electric furnace of 2000 degrees (℃) or higher, sublimation in which silicon carbide is used as a raw material and sublimed at a high temperature of 2000 degrees (℃) or higher to grow a single crystal method, a solution growth method using a crystal pulling method, and the like. In addition, a method of chemically depositing using a gas source has been used.

However, the Acheson method is very difficult to obtain a high-purity silicon carbide single crystal, and the chemical vapor deposition method may be able to grow only to a limited level of thin film thickness. Accordingly, research on a sublimation method for growing a crystal by sublimating silicon carbide at a high temperature has been focused. However, the sublimation method is also generally performed at a high temperature of 2400 ° C. or higher, and there is a high possibility of occurrence of various defects such as micropipes and stacking faults, so there is a limit in terms of production cost.

The present invention is to provide an apparatus and method for manufacturing a silicon carbide single crystal for supplying an additional raw material in a liquid state during the manufacturing process.

In addition, the technical problem to be solved by the present invention is not limited to the above-mentioned technical problem, and other technical problems not mentioned above will become clear to those skilled in the art from the description below. You will be able to understand.

An apparatus for manufacturing a silicon carbide single crystal according to an embodiment of the present invention includes a chamber, a crucible located in the chamber, a seed crystal moving into the crucible, a heating unit located on the outer circumferential surface of the crucible, and a raw material supply unit located in the chamber. The raw material supply unit includes a first container into which the raw material is charged, and an inlet pipe connected to the first container and through which the raw material moves, and a part of the inlet pipe overlaps the heating unit.

The inlet pipe may include a first region and a second region overlapping the heating unit, and the second region may overlap an outer circumferential surface of the crucible.

The raw material supply unit may further include a filter.

The filter may be located in the second region.

The first container may not overlap the heating unit.

The first container may include a first inlet, and the first inlet may have a funnel shape.

A first diameter of the first region may be different from a second diameter of the second region.

The second diameter may be smaller than the first diameter.

The second region may include a bent portion.

A method of manufacturing a silicon carbide single crystal according to an embodiment includes preparing a melt in a crucible, heating the crucible, and providing the seed crystal into the crucible, and heating the crucible. In the step of doing, the first raw material in a solid state located in a partial region of the raw material supply unit spaced apart from the crucible is changed into a liquid state by a heating process.

The first raw material in a liquid state may be provided into the crucible through a filter.

The crucible and the raw material supply unit may be located in a chamber.

According to the present invention, since it is possible to provide raw materials in a liquid state during the manufacturing process, it is possible to maintain a constant temperature of the melt in which crystal growth occurs. According to this, the quality of the obtained silicon carbide single crystal can be excellent.

1 is a schematic cross-sectional view of an apparatus for manufacturing a silicon carbide single crystal according to an embodiment.
2 is an enlarged view of a raw material supply unit according to an embodiment.
3 is a diagram of a raw material supply unit during a manufacturing process according to an embodiment.
4 and 5 are cross-sectional views of a raw material supply unit according to an exemplary embodiment.
6 is a schematic cross-sectional view of an apparatus for manufacturing a silicon carbide single crystal according to an embodiment.

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 have been omitted, and the same reference numerals are used for the same or similar components throughout the specification. In addition, since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present description is not necessarily limited to those shown.

In the drawings, the thickness is shown enlarged to clearly express the various layers and regions. Also, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation. When a part such as a layer, film, region, plate, etc. is said to be "on" or "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part in between.

Hereinafter, referring to FIGS. 1 to 3, a silicon carbide single crystal manufacturing apparatus and a silicon carbide single crystal manufacturing method using the same according to an embodiment will be described. 1 is a schematic cross-sectional view of an apparatus for manufacturing a silicon carbide single crystal according to an embodiment, FIG. 2 is an enlarged view of a raw material supply unit according to an embodiment, and FIG. 3 is a raw material supply unit during a manufacturing process according to an embodiment. It is a drawing for

First, referring to FIG. 1, an apparatus for manufacturing a silicon carbide single crystal according to an embodiment includes a reaction chamber 100, a crucible 300 located inside the reaction chamber 100, and a heating unit 400 for heating the crucible 300. , A rotating member 500 for rotating the crucible 300 and a raw material supply unit 600 are included.

The reaction chamber 100 is a sealed form including an empty inner space, and the inside thereof may be maintained in an atmosphere such as a constant pressure. Although not shown, a vacuum pump and a gas tank for atmosphere control may be connected to the reaction chamber 100 . After creating a vacuum inside the reaction chamber 100 using a vacuum pump and a gas tank for controlling the atmosphere, an inert gas such as argon gas may be filled.

The silicon carbide seed crystal 210 is a portion where a silicon carbide single crystal is grown, and is located in an upper region inside the crucible 300 . Depending on the manufacturing process, the lower surface of the silicon carbide seed crystal 210 may be positioned to contact the surface of the melt located inside the crucible 300 .

The silicon carbide seed crystal 210 is made of a single crystal of silicon carbide. The crystal structure of the silicon carbide seed crystal 210 is the same as that of the silicon carbide single crystal to be manufactured. For example, when a 4H polytype silicon carbide single crystal is manufactured, a 4H polytype silicon carbide seed crystal 210 can be used. In the case of using the 4H polytype silicon carbide seed crystal 210, the crystal growth plane is the (0001) plane or the (000-1) plane, or is inclined at an angle of 8 degrees or less from the (0001) plane or the (000-1) plane. It can be a photo side.

The seed crystal axis 230 extends to be connected to the upper surface of the silicon carbide seed crystal 210 to support the silicon carbide seed crystal 210 and to allow the silicon carbide seed crystal 210 to be positioned inside the crucible 300. do.

The seed crystal shaft 230 may rotate as well as move up and down with respect to the silicon carbide single crystal manufacturing device.

The crucible 300 is provided inside the reaction chamber 100 and may be in the form of a container with an open top. The crucible 300 may include an outer circumferential surface and a lower surface excluding the upper surface. However, any shape for forming the silicon carbide single crystal is possible without limitation to the above-described shape, and may include a cover covering the upper surface according to the manufacturing process. The crucible 300 may be loaded with a molten raw material such as silicon or silicon carbide powder.

The crucible 300 may be made of a material containing carbon such as graphite and SiC. The crucible 300 itself made of such a material may be used as a source of carbon raw material. Alternatively, a crucible made of a ceramic material may be used without being limited thereto, and at this time, a material or source to provide carbon may be provided separately.

The heating unit 400 may heat the crucible 300 to melt or heat the material accommodated in the crucible 300 . The heating unit 400 may be located on the outer circumferential surface of the crucible 300, and may have a shape surrounding the outer circumferential surface of the crucible 300, for example. Although the present specification shows an embodiment in which the heating unit 400 is located outside the chamber 100 and surrounds the crucible 300, it is not limited thereto and may be located inside the chamber 100, of course.

The heating unit 400 may use a resistance heating unit or an induction heating unit. Specifically, the crucible 300 is a resistance-type heating means in which the heating unit 400 itself generates heat, or an induction heating method in which the heating unit 400 includes an induction coil and heats the crucible 300 by flowing a high-frequency current through the induction coil. ) can be heated. However, it goes without saying that any heating member may be used without being limited to the above method.

An apparatus for manufacturing a single crystal of silicon carbide according to an embodiment may further include a rotating member 500 . The rotating member 500 may be coupled to the lower surface of the crucible 300 to rotate the crucible 300 . A high-quality silicon carbide single crystal can be grown on the silicon carbide seed crystal 210 as it is possible to provide a melt of uniform composition through rotation of the crucible 300 .

An apparatus for manufacturing a silicon carbide single crystal according to an embodiment may further include a raw material supply unit 600 . The raw material supply unit 600 may be located within the chamber 100 .

The raw material supply unit 600 includes a first container 610 into which the first raw material is charged, an inlet pipe 620 connected to the first container 610 and a passage through which the first raw material moves, and a filter 630. can do.

The first container 610 is a space into which the first raw material in an initial state is charged. The first container 610 may be loaded with a first raw material in a solid state, and the first container 610 may be disposed at a position that does not overlap with the heating unit 400 . Specifically, the first container 610 may be disposed at a position where the heating effect by the heating unit 400 does not reach. According to an embodiment, the chamber 100 including a heat-insulating material may include a protruding portion functioning as a partition, and the first container 610 may be positioned on the protruding portion. The first container 610 may be hardly affected by the heating unit 400 due to the protruding portion capable of insulation, and the first raw material loaded into the first container 610 may maintain a solid state. For example, the location where the first container 610 is disposed may have a temperature of about 1000 degrees (°C) to about 1200 degrees (°C).

The first vessel 610 according to an embodiment may include a silicon carbide material. The manufacturing process of the silicon carbide single crystal may be performed at about 1800 degrees (℃) to about 2000 degrees (℃), and the silicon carbide material has a melting point of about 2730 degrees (℃). The first container 610 made of silicon carbide may not react with the raw material charged in the first container 610 .

The first container 610 may include a first inlet 610a. The first inlet 610a may supply the first raw material loaded into the first container 610 to the inlet pipe 620 . The first inlet 610a may have any shape for supplying the first raw material in a solid state to the inlet pipe 620, but for example, the first inlet 610a may have a funnel shape. In this case, the first inlet 610a may have a first diameter D1 and a second diameter D2 , and may have a shape in which the diameter decreases toward the inlet pipe 620 . The first diameter D1 may be larger than the second diameter D2.

The first inlet 610a according to an embodiment may provide the first raw material in a solid state passing through the first inlet 610a to the inlet pipe 620 at a constant speed. The filling speed of the first raw material supplied to the inlet pipe 620 may be controlled by the second diameter D ₂ of the first inlet 610a, the density and diameter of the first raw material to be introduced, and the like. An inlet pipe 620 according to an embodiment may include a first region 620a and a second region 620b. The first region 620a may be connected to the first container 610 and may be a region into which the first raw material in a solid state is injected from the first container 610 .

The second region 620b may be connected to the first region 620a, and an end of the second region 620b may be connected to the filter 630.

The second region 620b may overlap the heating unit 400 . For example, the vicinity of the second region 620b overlapping the heating unit 400 may have a temperature of about 1400 degrees Celsius or higher during the manufacturing process. The first raw material may be, for example, silicon (Si), and since the melting point of silicon (Si) is 1400 degrees Celsius, the silicon introduced into the second region 620b may change into a liquid state.

The first raw material in a solid state injected through the first region 620a may be changed into the first raw material in a liquid state by the heating unit 400 overlapping the second region 620b. The liquid first raw material may be provided to the filter 630 through the second region 620b.

A supply rate of the first raw material supplied from the inlet pipe 620 to the crucible 300 may be determined by hydrostatic pressure acting on the first raw material in a liquid state. As shown in FIG. 2 , when the diameter of the second region 620b is constant, the supply speed of the added first raw material may be determined by the height L2 of the second region 620b.

Hereinafter, a diameter of the first injection hole 610a and a diameter of the second region 620b according to an exemplary embodiment will be described in detail.

First, the movement speed (Wt) of the first raw material introduced into the first region 620a through the first inlet 610a having a funnel shape as in an embodiment may be expressed as Equation (1) below.

식 (1)

Equation (1)

In Equation (1), ρ is the density of the first raw material in a solid state, g is the gravitational acceleration, D ₂ is the diameter of the tip of the first inlet 610a, d is the diameter of the first raw material, and k is 1.3 , K is 7, and D ₂ is greater than 5d.

The injection rate of the first raw material introduced into the first region 620a through the first inlet 610a may be determined through Equation (1) as described above.

Meanwhile, the second area 620b is an area occupied by the first raw material in a liquid state, and the height of the second area 620b may be maintained constant. To this end, an injection rate (Wt) of the first raw material in a solid state may be greater than a rate (Q) at which the first raw material in a liquid state is injected into the crucible.

The rate Q at which the liquid first raw material is injected into the crucible may be expressed by Equation (2) below.

식 (2)

Equation (2)

In Equation (2), ΔP is ρ*g*h, h is the height of the second region 620b, μ is the viscosity of the first raw material in a liquid state, and L _d is represented by Equation (3) below. And D can be represented by the following formula (4).

식 (3)

Equation (3)

식 (4)

Equation (4)

In the above equations (3) and (4), D is the diameter of the second region, V _d can be represented by the following equation (5), σ is the surface tension of the first raw material in a liquid state, and D _d is the It is the diameter of the first raw material in liquid state discharged from area 2.

식 (5)

Equation (5)

In Equation (5), D _d is the diameter of the first raw material in a liquid state discharged from the second region.

Using the above equations, the injection rate Q of the first raw material in a liquid state discharged from the second region may be determined according to the growth rate of the SiC single crystal. In this case, the injection rate Q may be adjusted by adjusting the diameter of the second region.

As an example, a case in which the height of the second region is 50 mm and D ₀ /d is 10 will be described. Looking at the contents attached to Table 1 below, by adjusting the diameter (D) of the second region to 0.2 mm to 0.5 mm in the range of the growth rate of the SiC single crystal from 0.29 g / h to 29.26 g / h, the first in the melt The first raw material may be injected in response to the consumption rate of the raw material (particularly Si). That is, the consumption rate of the first raw material is determined according to the growth rate of the single crystal, and the injection rate of the first raw material is determined according to the consumption rate. The diameter, the diameter of the second region, and the like can be adjusted.

[Table 1]

The filter 630 may prevent the first raw material, which does not melt in a liquid state but exists in a solid state, from flowing into the crucible 300 . The filter 630 may not pass the first raw material in a solid state while passing the first raw material in a liquid state.

An apparatus for manufacturing a silicon carbide single crystal according to an embodiment may be able to supply an additional raw material in a liquid state without including a separate additional heat source. Therefore, while the manufacturing process is simplified, a large amount of silicon carbide single crystals can be obtained. In addition, since the melt can maintain a constant temperature by supplying an additional raw material in a liquid state rather than a solid state, a silicon carbide single crystal of excellent quality can be obtained.

Hereinafter, a method for manufacturing a silicon carbide single crystal according to an embodiment will be described with reference to FIGS. 1 and 2 and FIG. 3 described above.

First, an initial molten raw material including silicon and metal is put into the crucible 300 made of graphite. The initial molten raw material may be in powder form or chunk type, but is not limited thereto. In addition, a first raw material in a solid form (for example, a powder form) is put into the first container 610 according to an embodiment.

Then, the crucible 300 in which the initial molten raw material is mounted is heated by using the heating unit 400 in an inert atmosphere such as argon gas. Upon heating, the initial molten raw material in the crucible 300 is changed into a molten liquid containing silicon and metal. As time progresses, the melt contains carbon drawn from the crucible. According to an embodiment, the initial molten raw material may include carbon.

After the crucible 300 reaches a predetermined temperature, the temperature of the crucible 300 is maintained and a silicon carbide single crystal may be precipitated from the surface of the seed crystal 210 . This uses the fact that the temperature of the seed crystal 210 is lower than the temperature of the melt inside the crucible 300. When silicon carbide becomes supersaturated in the vicinity of the seed crystal 210, a silicon carbide single crystal grows on the seed crystal 210 using the supersaturation as a driving force. In addition, the crystal growth may proceed while gradually lowering the temperature of the crucible 300 .

The silicon carbide single crystal grows further by taking in silicon and carbon from the melt. Accordingly, since silicon and carbon contained in the melt are gradually reduced and almost no metal is consumed, conditions for precipitating silicon carbide from the melt may change.

At this time, carbon may be continuously supplied from the crucible 300 . Melting of the crucible 300 continues by the metal included in the molten liquid, and carbon may be continuously supplied to the molten liquid.

According to this manufacturing process, the composition of the melt may be deficient in silicon. However, silicon may be continuously or discontinuously introduced during the manufacturing process through the raw material supply unit 600 according to an embodiment.

Specifically, the first raw material in a solid state introduced into the first container 610 may be supplied to the first region 620a and the second region 620b through the inlet 610a. In particular, in the process of heating the crucible 300 , the first raw material in a solid state may be changed into a liquid state by heating the heating unit 400 . The liquid first raw material may pass through the second region 620b and the filter 630 and be supplied to the crucible 300 .

According to an embodiment, the height L1 of the first region 620a and the height L2 of the second region 620b may be changed to control the supply speed of the raw material. Also, the diameter D3 of the first region 620a and the diameter D4 of the second region 620b may also be changed to control the supply speed of the raw material.

The raw material supply unit 600 according to an embodiment may inject the first raw material in a liquid state into the crucible 300 . When the solid-state first raw material is introduced into the crucible 300, an endothermic reaction may occur as the solid-state raw material is changed into a liquid-state raw material. In this case, since the temperature of the melt may change locally, it may be difficult to obtain a stable silicon carbide single crystal.

In addition, the first raw material that is not sufficiently dissolved in the melt acts as a nucleus for single crystal growth, so that silicon carbide can grow from undissolved silicon rather than silicon carbide seed crystals, and such precipitates adhere to the silicon carbide seed crystals The quality of the single crystal may deteriorate.

According to an embodiment, it may be possible to provide an additional raw material in a liquid state into the crucible by using a heating unit for heating the crucible even if a separate heating unit is not included. According to this, since the melt can maintain a stable temperature, a stable crystal growth environment for obtaining a silicon carbide single crystal can be maintained.

In the case of using the apparatus for manufacturing a silicon carbide single crystal according to an embodiment, it may be easy to introduce additional raw materials so that the melt maintains a constant composition even when the growth process proceeds. Accordingly, a process time for obtaining a silicon carbide single crystal may increase.

Hereinafter, with reference to FIGS. 4 and 5, a raw material supply unit included in an apparatus for manufacturing a silicon carbide single crystal according to an embodiment will be described. 4 and 5 are cross-sectional views of a raw material supply unit according to an exemplary embodiment. Descriptions of the same elements as those described in the foregoing drawings will be omitted.

First of all, referring to FIG. 4 , the diameter D5 of the first region 620a and the diameter D6 of the second region 620b may be different according to an exemplary embodiment. For example, the diameter D5 of the first region 620a may be greater than the diameter D6 of the second region 620b. A raw material flowing into the first region 620a may be in a solid state, and a raw material flowing into the second region 620b may be in a liquid state. The raw material in the liquid state introduced into the second region 620b is put into the crucible 300. For fine control of the amount injected into the crucible 300, the diameter D6 of the second region 620b is the first It may be smaller than the diameter D5 of the region 620a.

Referring to FIG. 5 , the second region 620b according to an exemplary embodiment may include connection parts 620b1 and 620b2 and a bent part 620b3.

A first raw material in a liquid state may be injected and/or charged into the connection portions 620b1 and 620b2 connected to the first region 620a. The first raw material in a liquid state may flow into the curved portion 620b3 having a curved shape at least twice.

At this time, when the level of the liquid first raw material flowing into the bent portion 620b3 increases, the liquid first raw material may naturally move toward the filter 630 and be discharged toward the crucible 300 by the siphon principle. there is.

Hereinafter, referring to FIG. 6, an apparatus for manufacturing a silicon carbide single crystal according to an exemplary embodiment will be described. 6 is a schematic cross-sectional view of an apparatus for manufacturing a silicon carbide single crystal according to an embodiment. A description of the same or similar configuration as the above-described embodiment may be omitted.

Referring to FIG. 6 , an apparatus for manufacturing a silicon carbide single crystal according to an embodiment may include a plurality of raw material supply units 600 .

In the case of using the seed crystal 210 having a relatively large diameter or performing the process under the condition of increasing the growth rate of the silicon carbide single crystal, the consumption rate of the melt may be fast. At this time, the apparatus for manufacturing a silicon carbide single crystal according to an embodiment includes a plurality of raw material supply units 600, so that despite a fast consumption rate of the melt, additional raw materials can be supplied so that the melt can maintain a constant composition.

Hereinafter, with reference to Table 2, the temperature change of the melt according to Examples and Comparative Examples will be described. The calculation results obtained using the thermodynamics program (FactSage) are classified into comparative examples and examples and are attached to Table 2 below.

Comparative Examples 1 to 5 are cases in which Si in a solid state having various temperatures is added to a metal solution (a melt according to an embodiment). The temperature change of the metal solution for Comparative Examples 1 to 5 was examined. As in Comparative Examples 1 to 5, when solid state Si was added at various temperatures, it was confirmed that the temperature of the metal solution dropped to 1749.6 degrees (° C.).

On the other hand, referring to Examples 1 to 4, when Si in a liquid state having a predetermined temperature is added to the metal solution, there is almost no change in the temperature of the metal solution according to the amount added, and the temperature of the metal solution is almost constant even after adding the additional raw material. was found to be maintained.

That is, when the additional raw material in a solid state is charged as in Comparative Examples 1 to 5, the temperature of the melt may change significantly, and thus the quality of the obtained silicon carbide single crystal may be significantly deteriorated. However, in the case of using the apparatus for manufacturing a silicon carbide single crystal according to an embodiment, since an additional raw material heated in a liquid state can be charged, the temperature of the melt charged into the crucible is maintained almost constant, and a silicon carbide single crystal of excellent quality is maintained therefrom. know that it can be obtained.

[Table 2]

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

100: chamber
210: seed crystal
300: crucible
400: heating unit
600: raw material supply unit

Claims (12)

chamber,
A crucible located in the chamber,
Seed crystals moving into the crucible,
A heating unit located on the outer circumferential surface of the crucible, and
A raw material supply unit located in the chamber,
The raw material supply unit,
A first container into which raw materials are charged, and
An inlet pipe connected to the first container and through which the raw material moves,
The inlet pipe includes a first region and a second region disposed at a position overlapping the heating part,
The second region is located in contact with the outer circumferential surface of the crucible,
The second region is a manufacturing device of a silicon carbide single crystal connected to the filter. delete delete delete In paragraph 1,
The first container is a silicon carbide single crystal manufacturing device that does not overlap with the heating unit. In paragraph 1,
The first container includes a first inlet,
The first injection port is a manufacturing apparatus of a silicon carbide single crystal having a funnel shape. In paragraph 1,
An apparatus for producing a silicon carbide single crystal in which a first diameter of the first region and a second diameter of the second region are different. In paragraph 7,
The second diameter is a device for producing a silicon carbide single crystal smaller than the first diameter. In paragraph 1,
The second region is an apparatus for manufacturing a silicon carbide single crystal including a bent portion. Preparing a melt in a crucible;
heating the crucible; and
Providing a seed crystal into the crucible,
In the step of heating the crucible,
A first raw material in a solid state located in a partial region of the raw material supply unit spaced apart from the crucible is changed into a liquid state by a heating process,
The first raw material is provided in a liquid state inside the crucible through a filter connected to the raw material supply unit. delete In paragraph 10,
The crucible and the raw material supply method of manufacturing a silicon carbide single crystal located in the chamber.

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