KR101226529B1 - Apparatus for growing single crystal - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal growth apparatus capable of easily growing crystals with uniform solute distribution, generating ingots containing less impurities, and efficiently controlling the rate of crystal growth.
To this end, the single crystal growth apparatus according to the present invention has a crucible in which a groove for fixing seed crystals is formed on an inner bottom surface, a heater portion formed adjacent to the outside of the crucible, and a refrigerant is circulated to the groove side of the crucible bottom. A heat exchange part for cooling the lower part of the crucible, a growth furnace accommodating the crucible, the heater part, and the heat exchange part therein, and a crucible vertical motion part for moving the crucible vertically in the growth path are disclosed.

Description

Single Crystal Growth Device {APPARATUS FOR GROWING SINGLE CRYSTAL}

The present invention relates to a single crystal growth apparatus.

In general, as the single crystal growth method, Bernoulli method, Czochralski (CZ) method, Bridgman method, heat exchange (HEM) method and the like are generally used.

The Bernoulli method is a method in which alumina powder is passed through an oxygen-hydrogen flame to melt, and then the melt is dropped onto a seed crystal while simultaneously rotating the crystal to obtain a crystal. In this method, crystal growth is easy and crystals can be grown most inexpensively, but crystals are subjected to high thermal shock during crystal growth, and cracks easily occur, and they are difficult to use for watches and decorative purposes in terms of quality and size. There are disadvantages.

The Czochralski method has the advantage of free diameter control and high productivity with long lengths.However, in crystal growth of brittle materials such as sapphire single crystals, vibrations or cores generated by pullers while rotating and raising the temperature gradient and crystals Due to the negative stress concentration, the diameter of the single crystal is limited and the growth axis direction is limited.

The Bridgman method is a method of growing a single crystal by immersing the raw powder in a crucible and melting the crucible, then slowly moving the crucible to a low temperature region below the melting point of the raw material. The Bridgman method can grow polycrystals of the columnar in the vertical direction, but has a disadvantage in that seeding is difficult.

The heat exchange method is a method in which a raw material powder and a single crystal seed are contained in the lower part of the crucible, the raw material powder is melted, and the raw material material is solidified from the seed by solidification by cooling using a heat exchanger under the crucible. This heat exchange method produces a large temperature gradient inside the crucible, so that less impurities are contained in the product, and in particular, a large temperature gradient at the inner center of the crucible and the outer wall of the crucible can prevent contamination from the crucible outer wall. However, the heat exchange method can cause product defects due to the large temperature gradient inside the crucible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a single crystal growth apparatus capable of easily growing crystals of uniform solute distribution, generating ingots with less impurities, and controlling the rate of crystal growth efficiently.

In order to achieve the above object, the single crystal growth apparatus according to the present invention includes a crucible in which grooves for fixing seed crystals are formed on an inner bottom thereof; A heater unit formed adjacent to the outside of the crucible; A heat exchanger for cooling the lower part of the crucible by circulating a refrigerant to a groove side of the lower part of the crucible; A growth furnace accommodating the crucible, the heater part and the heat exchange part therein; And a crucible vertical movement part for moving the crucible vertically in the growth path.

Here, a cooling unit for cooling the lower portion of the crucible and for cooling the refrigerant discharged from the heat exchange unit; And a refrigerant storage unit storing the refrigerant cooled in the cooling unit and supplying the cooled refrigerant to the heat exchange unit.

In addition, the cooling unit coolant storage unit for storing and discharging the cooling water; And a coolant cooling unit cooling the coolant discharged from the heat exchange unit by a heat exchange method using the coolant discharged from the coolant storage unit.

In addition, the heat exchanger may include a cooling water circulation tube through which the cooling water discharged from the cooling water storage unit circulates.

The heater unit may include an upper heater formed to be spaced apart from the outside of the crucible on an upper portion of the growth path; A lower heater formed below the growth path to be spaced apart from the outside of the crucible; And an insulating member positioned between the upper heater and the lower heater.

The heat exchange part may include a refrigerant supply pipe configured to supply a refrigerant to a groove side of the lower portion of the crucible; And it may include a refrigerant discharge pipe is formed so as to discharge the refrigerant cooling the lower portion of the crucible.

In addition, the coolant discharge pipe may be bifurcated to be adjacent to both sides of the coolant supply pipe.

In addition, the upper end of the refrigerant discharge pipe of the two branches is formed higher than the upper end of the refrigerant supply pipe, it may be formed to surround the groove side of the lower portion of the crucible.

In addition, the growth pump may further include a vacuum pump unit for adjusting the air pressure.

The single crystal growth apparatus according to the present invention has a low horizontal temperature gradient at the center of the crucible, so that crystal growth of a uniform solute distribution is easy. In addition, the single crystal growth apparatus according to the present invention has a small content of impurities in the ingot produced. In addition, the single crystal growth apparatus according to the present invention can precisely control the rate of crystal growth and the like through the adjustment of the heat exchanger under the crucible as well as the temperature control of the heater outside the crucible.

1 is a conceptual diagram briefly showing a single crystal growth apparatus according to the present invention.
2A is an enlarged view of A of FIG. 1.
2B is an enlarged view of a heat exchanger according to another embodiment of the present invention.
2C is an enlarged view of a heat exchanger according to still another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention.

Hereinafter will be described the configuration and operation principle of a single crystal growth apparatus according to an embodiment of the present invention.

1 is a conceptual diagram briefly showing a single crystal growth apparatus according to the present invention according to the present invention. 2A is an enlarged view of A of FIG. 1. And the inside of the growth path of FIG. 1 corresponds to a longitudinal cross-sectional view.

1 and 2A, the single crystal growth apparatus 100 according to the present invention includes a crucible 110, a heater 120, a heat exchanger 130, a growth furnace 140, and a crucible vertical movement unit 150. Include. In addition, the single crystal growth apparatus 100 according to the present invention may further include a refrigerant storage unit 160, a cooling unit 170, a vacuum pump unit 180, and a controller 190.

The crucible 110 has a space formed therein. In addition, a groove 111 into which the seed 10 is inserted is formed at a lower surface of the inner space of the crucible 110. In addition, the crucible 110 may be made of one of molybdenum and equivalent materials, but is not limited thereto.

The heater 120 is formed to include the upper heater 121, the lower heater 122 and the heat insulating member 123. The upper heater 121 is formed on the growth path. In addition, the upper heater 121 is formed to be spaced apart from the outside of the crucible 110 when the crucible 110 is moved upward. The lower heater 122 is formed at the bottom of the growth furnace. When the crucible 110 moves downward, the lower heater 122 is formed to be spaced apart from each other to surround the outside of the crucible 110. The upper heater 121 and the lower heater 122 may be formed of a heating coil, and the temperature thereof may be adjusted according to the control of the controller 190 to be described later. That is, the upper heater 121 and the lower heater 122 may be temperature controlled to suit the melting and single crystal growth of the raw material contained in the crucible 110. Specifically, the temperature of the upper heater 121 is maintained at a high temperature above the melting point so that the raw material is liquefied (20), the temperature of the lower heater 122 is a low temperature below the melting point so that the raw material can crystallize (30) Can be maintained. A temperature gradient from high temperature to low temperature is formed in the vertical direction by the upper heater 121 and the lower heater 122. The heat insulating member 123 may be located between the upper heater 121 and the lower heater 122. Since the heat insulating member 123 is present between the upper heater 121 and the lower heater 122, a gentle temperature gradient appears from the upper heater 121 side to the lower heater 122 side.

The heat exchanger 130 is formed to include the refrigerant supply pipe 131 and the refrigerant discharge pipes 132 and 133. The heat exchanger 130 is formed to support the lower end of the crucible 110. The coolant supply pipe 131 is formed in the shape of a pipe so that the coolant is supplied to the groove 111 side of the lower portion of the crucible 110. The refrigerant discharge pipes 132 and 133 are formed in the shape of a tube so that the coolant cooled in the lower portion of the crucible 110 is discharged. The refrigerant discharge pipes 132 and 133 may be divided into two parts at the upper end of the refrigerant supply pipe 131, and may be formed to be in contact with one side and the other side of the refrigerant supply pipe 131, respectively. By using the heat exchanger 130, precise temperature control of the seed 10 and the raw material formed on the groove 111 side in the crucible 110 is possible. In particular, when the crystal growth is performed only by the vertical movement of the heater 120 and the crucible 110, the raw material inside the crucible 110 is higher in temperature near the outer wall of the crucible 110 on the same plane. In the crucible 110, the central temperature side is formed a low temperature gradient. That is, the horizontal temperature gradient of the raw material in the crucible 110 is large. However, the single crystal growth apparatus 100 according to the present invention further arranges the heat exchanger 130 at the lower center side of the crucible 110 so that the horizontal temperature gradient as described above can be controlled less, so that the inside of the crucible 110 can be controlled. The solid-liquid interface of the raw material in the center portion becomes flat, thereby facilitating crystal growth of uniform solute distribution. The configuration of the heat exchanger 130 may be various embodiments. This will be described later.

Growth path 140 may be in the shape of a rectangular parallelepiped having a space therein. The growth furnace 140 accommodates the crucible 110, the heater 120, and the heat exchanger 130 therein.

The crucible vertical movement part 150 is formed at the lower side of the crucible 110. In addition, the crucible up and down movement part 150 is formed to vertically move the crucible 110 into the upper heater 121 and the lower heater 122 inside the growth furnace 140. Specifically, the crucible up and down movement unit 150 may be formed of a rack gear and a pinion gear, but the configuration is not limited thereto.

The coolant storage unit 160 is a coolant tank that stores the cooled coolant. The refrigerant stored in the refrigerant storage unit 160 is supplied to the refrigerant supply pipe 131 of the heat exchange unit 130. The amount and speed of the refrigerant discharged from the refrigerant storage unit 160 are controlled by the valve 160a. In addition, the refrigerant may be helium (He) gas, but the material is not limited thereto.

The cooling unit 170 is formed to include the cooling water storage unit 171 and the refrigerant cooling unit 172. The coolant storage unit 171 is a tank that stores the coolant required to cool the lower portion of the crucible 110 and the coolant having the elevated temperature. The coolant cooler 172 cools the coolant discharged from the coolant discharge pipes 132 and 133 through heat exchange with the coolant of the coolant storage unit 171. At this time, the amount and speed of the cooling water of the cooling water storage unit 171 is controlled by the valve (171a).

The vacuum pump unit 180 may be a rotary pump or the like. Then, the vacuum pump unit 180 is formed on one side of the growth path. In addition, the vacuum pump unit 180 may make the interior of the growth path 140 into a vacuum state in accordance with the single crystal growth conditions.

The controller 190 is formed to control the temperature of the upper heater 121 and the lower heater 122 of the heater 120. Specifically, when the upper heater 121 and the lower heater 122 is formed of a coil heater, the temperature is controlled by adjusting the amount of current flowing therethrough. The controller 190 controls the crucible up and down movement unit 150 to control the up and down movement inside the growth path 140 of the crucible 110. In addition, the controller 190 controls the valve 160a of the coolant storage unit 160 to control the amount and speed of the coolant for cooling the lower portion of the crucible 110. In addition, the controller 190 may control the valve 171a of the coolant storage unit 171 to control the amount and speed of the coolant for cooling the coolant.

In the single crystal growth apparatus 100 according to the present invention, not only the operation of the heater 120 and the crucible up and down movement 150, but also the operation of the heat exchanger 130 under the heater 120, the temperature of the single crystal growth material. Precise control is possible. Therefore, the solid-liquid coexistence region within the crucible 110 of the single crystal growth material can be adjusted small, thereby reducing casting defects such as microsegregation, microporosity, and freckles. .

Hereinafter, the configuration of a single crystal growth apparatus according to another embodiment of the present invention will be described.

1 is a conceptual diagram briefly showing a single crystal growth apparatus according to the present invention according to the present invention. Figure 2b is an enlarged view of the heat exchange unit of the single crystal growth apparatus according to another embodiment of the present invention.

FIG. 2B is an enlarged view of the same point in time as that of FIG. 2A, and the configuration of the single crystal growth apparatus is the same except for the configuration of the heat exchanger 230. Therefore, hereinafter, the structure of the heat exchange part 230 of the single crystal growth apparatus according to another embodiment of the present invention will be described.

The heat exchanger 230 is formed to include the refrigerant supply pipe 231 and the refrigerant discharge pipe 232. The coolant supply pipe 231 has a pipe shape, and supplies the coolant to cool the seed 10 at the bottom of the crucible 110. The refrigerant discharge pipes 232 and 233 are formed in the shape of a pipe divided into two branches at the upper end of the refrigerant supply pipe 231. The refrigerant discharge pipes 232 and 233 may be formed to be adjacent to one side and the other side of the refrigerant supply pipe 231. In addition, the upper end (232a, 233a) of the refrigerant discharge pipe (232, 233) is formed higher than the upper end (231a) of the refrigerant supply pipe (231), so as to surround the seed (10). As a result, the coolant supplied through the coolant supply pipe 231 can maintain a long residence time on the lower side of the crucible 110, and thus more precisely control the temperature control of the lower seed 10 portion of the crucible 110.

Hereinafter will be described the configuration of the heat exchanger according to another embodiment of the present invention.

1 is a conceptual diagram briefly showing a single crystal growth apparatus according to the present invention according to the present invention. Figure 2c is an enlarged view of the heat exchange unit of the single crystal growth apparatus according to another embodiment of the present invention.

FIG. 2B is an enlarged view of the same point in time as that of FIG. 2A, and the configuration of the single crystal growth apparatus is the same except for the configuration of the heat exchanger 330. Therefore, hereinafter, the structure of the heat exchange part 330 of the single crystal growth apparatus according to another embodiment of the present invention will be described.

The heat exchanger 330 is formed to include a coolant supply pipe 331, a coolant discharge pipe 332, and a coolant circulation pipe 334 and 335. The coolant supply pipe 331 has a pipe shape, and supplies the coolant to cool the seed 10 at the bottom of the crucible 110. The refrigerant discharge pipes 332 and 333 are formed in the shape of a pipe divided into two branches at the upper end of the refrigerant supply pipe 331. The refrigerant discharge pipes 332 and 333 may be formed to be adjacent to one side and the other side of the refrigerant supply pipe 331. Each of the cooling water circulation pipes 334 and 335 is formed in the shape of a pipe so as to be adjacent to the outside of the refrigerant discharge pipes 332 and 333. In addition, the coolant of the coolant storage unit 171 is circulated in the coolant circulation pipes 334 and 335. As a result, the lower portion of the crucible 110 of the refrigerant discharge pipes 332 and 333 may be cooled, and the refrigerant having a raised temperature may be cooled more efficiently.

As described above, the present invention is not limited to the above-described specific preferred embodiments, and any person skilled in the art may apply the present invention without departing from the gist of the present invention. It is to be understood that various changes and modifications may be practiced within the scope of the appended claims.

100; Single crystal growth apparatus
110; Crucible 120; Heater
130; Heat exchanger 140; Growing road
150; Crucible vertical movement unit 160; Refrigerant storage unit
170; Cooling unit 180; Vacuum pump
190; The control unit

Claims (9)

A crucible in which grooves are formed on the inner bottom to fix the seed crystals;
A heater unit formed adjacent to the outside of the crucible;
A heat exchanger for cooling the lower part of the crucible by circulating a refrigerant to a groove side of the lower part of the crucible;
A growth furnace accommodating the crucible, the heater part and the heat exchange part therein; And
It includes a crucible vertical movement for moving the crucible in the vertical direction in the growth path,
The heater part
An upper heater formed at an upper portion of the growth path to be spaced apart from the outside of the crucible;
A lower heater formed below the growth path to be spaced apart from the outside of the crucible; And
It includes a heat insulating member located between the upper heater and the lower heater,
The heat exchanger
A refrigerant supply pipe configured to supply refrigerant to a groove side of the lower portion of the crucible; And
And a refrigerant discharge pipe configured to discharge the refrigerant cooled in the lower part of the crucible,
The refrigerant discharge pipe is bifurcated so as to be adjacent to both sides of the refrigerant supply pipe,
The upper end of the refrigerant discharge pipe of the two branches is formed higher than the upper end of the refrigerant supply pipe, it characterized in that the single crystal growth apparatus is formed to surround the groove side of the lower portion of the crucible. The method of claim 1,
A cooling unit for cooling the lower portion of the crucible and cooling the refrigerant discharged from the heat exchange unit; And
And a refrigerant storage unit storing the refrigerant cooled in the cooling unit and supplying the cooled refrigerant to the heat exchange unit. The method of claim 2,
The cooling unit
Cooling water storage unit for storing and discharging the cooling water; And
And a refrigerant cooling unit cooling the refrigerant discharged from the heat exchange unit by a heat exchange method using the cooling water discharged from the cooling water storage unit. The method of claim 3, wherein
The heat exchange unit is a single crystal growth apparatus further comprises a cooling water circulation pipe through which the cooling water discharged from the cooling water storage unit circulates. delete delete delete delete The method of claim 1,
Single crystal growth apparatus further comprises a vacuum pump unit for adjusting the air pressure of the growth furnace.

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