KR20120091576A - Apparatus for growing single crystal using micro-wave and method for growing the same - Google Patents

Abstract

PURPOSE: An apparatus and method for growing a single crystal using a micro wave are provided to minimize a temperature deviation in a crucible by raising and maintaining a temperature due to heat from ceramic single crystal materials and a heater. CONSTITUTION: A growing furnace(10) includes an insulation pelt inside. A crucible(20) is installed in the inside of the insulation pelt. A main heating unit(30) provides heat to the crucible. An auxiliary heating unit(60) heats the single crystal materials in the crucible. A cooling unit(80) supplies refrigerant to a cooling chamber.

Description

Single crystal growth apparatus using microwave and its growth method {APPARATUS FOR GROWING SINGLE CRYSTAL USING MICRO-WAVE AND METHOD FOR GROWING THE SAME}

The present invention relates to a single crystal growth apparatus and a growth method thereof, and more particularly, to a single crystal growth apparatus using a microwave and a growth method thereof.

Recently, with the development of electric and electronic technology, the demand for ceramic single crystals having excellent optical and physical properties is increasing in the display field.

In particular, sapphire is a single crystal of α-Al ₂ O ₃ , which has excellent mechanical properties, corrosion resistance, heat resistance and broad light transmittance, as well as high hardness, thermal conductivity, electrical resistance, high impact resistance, and strong dielectric strength. It is used as a basic substrate for blue, green light emitting diodes (LEDs), blue laser diodes (LDs), and DVD data storage devices as a substrate for growing substrates and gallium nitride (GaN). It is widely used for a wide variety of applications such as glass.

However, sapphire is difficult to produce cracks and pores during crystal growth due to lattice anisotropy of α-Al ₂ O ₃ having a rhombohedral structure. Growth methods are being studied.

As a manufacturing method which can obtain a sapphire single crystal to date, the Bernoulli method, Czochralski method, Bridgman method, EFG method, Kyoropolos method, HEM method (Heat Exchange Method) are mentioned as an example.

The Bernoulli method is a method in which the alumina powder is melted with a torch flame of oxygen-hydrogen during free fall, falling onto the seed crystals and crystallized while rotating down. This method has a lot of impurities, pores, crystal distortions, residual stresses, etc. inside the single crystal, which makes it difficult to use for applications other than those used for clock glass and other raw materials for sapphire single crystal manufacturing apparatus.

The Czochralski method is a method of manufacturing a single crystal while rotating seed by contacting the surface of the alumina solution. Although about 80% of the surrogate substrate is manufactured by this method, crystals of a brittle material such as sapphire single crystal In growth, there is a problem that crystal defects are likely to increase due to vibration caused by a high temperature gradient and puller, stress concentration at the neck portion, fluctuations in the molten metal, and the like, and cracks are likely to occur.

In order to solve the drawbacks of the Czochralski method, the EFG method has a method of depositing molybdenum die having a desired shape in an alumina solution and growing by surface tension, but has a problem of high defect density and poor productivity.

Heat exchange method (HEM) is a method of growing single crystals by precisely controlling the temperature by installing a heat exchanger at the lower part of the high temperature part where the temperature is uniform, and it is not necessary to move the crystal itself for solidification. It is a method to grow excellent single crystals. However, this method, despite its excellent characteristics, has a problem in that thermal convection becomes more severe as a single crystal grows to a larger diameter and it is difficult to realize a stable temperature gradient, resulting in many pores and lattice defects.

Exemplary embodiments of the present invention can grow a ceramic single crystal, and by using a microwave to raise and maintain the temperature by self-heating of the heater and the ceramic single crystal raw material, the temperature variation in the crucible is small, the temperature gradient and temperature control is An easy single crystal growth apparatus and its growth method are provided.

Single crystal growth apparatus according to an exemplary embodiment of the present invention, the growth furnace constituting a thermal insulation felt therein; A crucible installed inside the thermal insulation felt, the seed crystal is located to accommodate the single crystal raw material; A main heating unit configured at an outer side of the crucible and providing heat to the crucible; An auxiliary heating unit mounted to the growth furnace and heating the single crystal raw material in the heating unit and the crucible as a microwave; A heat exchanger configured at a lower side of the crucible and configured to exchange heat with the crucible; And a cooling unit installed on an outer wall of the growth furnace, the cooling unit supplying a refrigerant to the cooling chamber.

In the single crystal growth apparatus, the auxiliary heating unit may include a magnetron that generates microwaves in the growth furnace.

In the single crystal growth apparatus, the single crystal raw material in the main heating unit and the crucible can self-heat by the microwaves.

In the single crystal growth apparatus, the single crystal raw material may be any one selected from alumina (Al ₂ O ₃ ), aluminum nitride (AIN), silicon (Si), and gallium nitride (GaN).

In addition, in the single crystal growth apparatus, the main heating unit may include a single or a plurality of heaters sequentially installed on the outside of the crucible.

In the single crystal growth apparatus, the heater is characterized in that the thickness of the upper end is greater than or equal to the thickness of the lower end.

In addition, in the single crystal growth apparatus, the main heating unit may include at least one selected from a first heater, a second heater, and a third heater sequentially installed outside the crucible.

In the single crystal growth apparatus, the first to third heaters may include graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), and tungsten (W). ) And zirconium dioxide (ZrO ₂ ) may include one or more selected from the group consisting of.

In the single crystal growth apparatus, the crucible may be graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W), and zirconium dioxide ( ZrO ₂ ) may include one or more selected from the group consisting of.

In the single crystal growth apparatus, the growth path may grow a single crystal in any one atmosphere selected from the group consisting of a vacuum atmosphere and an inert gas atmosphere.

A single crystal growth method according to another exemplary embodiment of the present invention includes the steps of (a) placing a seed crystal at the bottom of the crucible configured inside the heater; (B) filling a single crystal raw material on the seed crystal; (C) heating the heater and the single crystal raw material by using a microwave to form a uniform molten raw material; (D) cooling the seed crystals by using a heat exchanger provided under the crucible so that the seed crystals do not melt in parallel with step (c); (E) growing the uniform molten raw material from the seed crystal to a single crystal; And (f) growing the uniform molten raw material into single crystal by controlling a temperature gradient between the uniform molten raw material and the growing single crystal in parallel with step (e). have.

In the single crystal growth method, the heater and the single crystal raw material may self-heat by irradiating the microwaves.

In the single crystal growth method, the heater may include at least one selected from the group consisting of a first heater, a second heater, and a third heater that are sequentially installed on the outside of the crucible.

In the single crystal growth method, the first heater, the second heater, or the third heater may include graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), and molybdenum (Mo). , Tungsten (W) and zirconium dioxide (ZrO ₂ ) may include one or more selected from the group consisting of.

In the single crystal growth method, the crucible is graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide (ZrO). _It may comprise one or more selected from the group consisting of ₂ ).

According to the exemplary embodiment of the present invention as described above, by using the microwave at the same time heating the main heating unit and the raw material in the crucible it is possible to secure the reaction stability in the crucible through the removal of moisture at the initial temperature rise.

In addition, in the present embodiment, a large diameter high-quality single crystal can be economically grown by arbitrarily forming a temperature gradient according to the cross-sectional area, weight, and shape of the first to third heaters of the main heating unit to adjust the growth rate of the single crystal. .

In addition, in the present embodiment, the charging height of the raw material can be lowered as much as possible, and when the temperature rises, the reaction material can be stabilized in the furnace by minimizing the reactant at the high temperature as well as at the low temperature. The ability to produce with equipment can reduce manufacturing costs in terms of equipment price and power costs.

In addition, in the present embodiment, by heating the raw material in the main heating unit and the crucible simultaneously using microwaves, the temperature deviation and the temperature gradient of the heater and the heated object, which are problems of the electric furnace and the high frequency furnace, can be adjusted, so that convection of the molten metal in the molten state is achieved. It is possible to grow high quality single crystal by suppressing the phenomenon as much as possible.

In addition, in this embodiment, due to the simultaneous heating of the main heating unit and the raw material can significantly reduce the manufacturing cost by reducing the temperature rise time, it can exhibit an economically excellent effect by reducing the power consumption.

In addition, in this embodiment, the temperature, temperature, and shape of the first to third heaters constituting the main heating unit may be arbitrarily adjusted by differently setting the melt state of the seed crystal using a probe rod. As can be seen, the probability of failure of single crystal growth can be significantly reduced.

Since these drawings are for reference in describing exemplary embodiments of the present invention, the technical idea of the present invention should not be construed as being limited to the accompanying drawings.
1 is a schematic view showing a single crystal growth apparatus according to an exemplary embodiment of the present invention.
2 is a view showing a sapphire single crystal prepared by an exemplary embodiment of the present invention.
3 is a cross-sectional view of a wafer made of sapphire single crystal prepared by an exemplary embodiment of the present invention.
FIG. 4 is a diagram illustrating an X-ray diffraction photograph of one portion of the cross section of the wafer of FIG. 3.
FIG. 5 is a diagram illustrating an X-ray diffraction photograph of two portions of the cross section of the wafer of FIG. 3.
FIG. 6 is a diagram illustrating an X-ray diffraction photograph of three portions of the cross section of the wafer of FIG. 3.
FIG. 7 is a diagram illustrating an X-ray diffraction photograph of four portions of the cross section of the wafer of FIG. 3.
8 is a view showing an X-ray diffraction image for measuring the crystal growth direction of the single crystal prepared by the exemplary 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 may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In addition, since the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. When a part of a layer, film, area, plate, etc. is said to be “on” or “on” another part, this includes not only the other part “right on” but also another part in the middle.

1 is a schematic view showing a single crystal growth apparatus according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the single crystal growth apparatus 100 according to an exemplary embodiment of the present invention is for growing single crystals of ceramics, and more preferably, alumina (Al), which is applied to a display field due to excellent optical and physical properties, may be used. ₂ O ₃ ) is for growing single crystal, sapphire single crystal.

Here, in the single crystal growth apparatus 100 according to the present embodiment, a heat exchange method for growing a ceramic single crystal may be applied by forming a heat exchange means at a lower portion of a high temperature portion having a uniform temperature to precisely control the temperature. have.

In this case, the heat exchange method is a method of growing a single crystal having a good diameter and quality because the growth occurs in a stable temperature gradient while the single crystal is manufactured, and it is not necessary to move the crystal itself to solidify.

The single crystal growth apparatus 100 according to the exemplary embodiment of the present invention basically includes a growth furnace 10, a crucible 20, a main heating unit 30, an auxiliary heating unit 60, and heat exchange. The unit 70 and the cooling unit 80 are configured to be described.

In the present embodiment, the growth path 10 is a chamber unit that can create a vacuum atmosphere, an inert gas atmosphere, or an atmosphere atmosphere therein, and functions to substantially support the following various components.

The growth furnace 10 as described above may consist of one facility or a fractionated facility, and is provided with various elements such as brackets, blocks, plates, covers, and collars.

Since these accessory elements are for installing the elements constituting the apparatus 100 in the growth furnace 10, in this specification, except for exceptional cases, these accessory elements are collectively referred to as a growth furnace.

In addition, the growth path 10 includes various motor drive units, pump units, high pressure air units, vacuum composition units, electronic control units, and the like for driving the apparatus 100.

On the other hand, the inside of the growth path 10 as described above may be configured to the heat insulating means for preventing the heat radiated from the main heating unit 30 to be described later to be discharged to the outside.

The heat insulating means includes a heat insulating felt 11 fixed to the top, the center and the bottom inside the growth path (10).

The thermal insulation felt 11 may be made of boron nitride (BN), pyrolytic boron nitride (PBN), zirconium dioxide (ZrO ₂ ), and Al ₂ O ₃ (alumina), which may be used even at a high temperature and have excellent thermal insulation effect.

Here, a tungsten ring or Mo ring (not shown) may be installed between the heat insulating felt 11 and the inner wall of the growth furnace 10 so as to perform a more effective heat insulating action.

On the other hand, the growth furnace 10 may create a vacuum atmosphere through the vacuum composition unit (not shown in the drawings) mentioned above.

The vacuum composition unit uses a vacuum pump such as a rotary pump, and vacuums the inside of the growth furnace 10 to approximately 10 ^-3 Torr through the gas inlet 13, which is a vacuum forming hole located below the growth furnace 10. Can be formed.

In addition, the growth path 10 may create an inert gas atmosphere such as Ar and N ₂ through a gas injection valve (not shown).

In the present embodiment, the crucible 20 accommodates the single crystal raw material 1 (hereinafter referred to as “raw material” for convenience), more preferably sapphire single crystal raw material, and further described in the main heating unit 30 and It is for melting the raw material through the auxiliary heating unit (60).

The single crystal raw material may be any one selected from alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon (Si), and gallium nitride (GaN).

The crucible 20 has a thickness of about 0.6t, a seed crystal (not shown) is located at the lower end (bottom portion) of the inside, and may be configured inside the thermal insulation felt 11.

It is possible to manufacture a variety of ceramic single crystal using the single crystal growth apparatus of the present invention, and will be described below with an example of growing a sapphire single crystal.

The crucible 20 can be used at a high temperature above the melting point of the ceramic raw material (for example, at a melting point of 2050 ° C or higher in the case of sapphire), does not react with the ceramic at this high temperature, is easily formed or processed, and ceramic single crystal growth. Later, single crystals can be easily separated, have sufficient mechanical strength to support the melt at high temperatures, and can be manufactured as economical materials.

To satisfy this, the crucible 20 is made of graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide (ZrO _2). It may comprise one or more selected from the group consisting of.

In the present embodiment, the main heating unit 30 is to provide heat of a predetermined temperature to the crucible 20 so as to melt the raw material, it may be configured outside the crucible 20.

The main heating unit 30 may include a single or a plurality of heaters sequentially installed on the outside of the crucible 20, and more preferably, the first heater 41, the second heater 42, and At least one of the third heaters 43 may be included. Here, the first heater 41, the second heater 42, and the third heater 43 may be each singular or plural first heaters, singular or plural second heaters, and singular or plural third heaters. It may be provided. Here, the heaters 41, 42, and 43 may have a thickness at the top of the heater being greater than or equal to a thickness at the bottom.

The first to third heaters 41, 42, and 43 are formed as heating elements that can be heated by self-heating by microwave irradiation.

These first to third heaters (41, 42, 43) of the side is made of a shape similar to the side of the crucible 20, cylinder, triangular column, square column, pentagonal column, hexagonal column, seven-column column, octagonal column, Triangular pyramid, square pyramid, pentagonal pyramid, hexagonal pyramid, heptagonal pyramid and octagonal pyramid may be made of any one or more of various shapes.

Here, the first heater 41 is formed as a porous and is provided for the buffering effect of the rapid thermal shock and the temperature preservation in the crucible 20.

The second heater 42 may be formed of a high density material to sufficiently supply heat to the crucible 20.

The third heater 43 is formed of a high-density material whose surface is polished to block and disperse radiant heat, thereby maintaining a constant heat distribution.

In this case, the first to third heaters 41, 42, and 43 may include graphite, silicon carbide, silicon pyrolytic boron nitride (PBN), molybdenum (Mo), and tungsten ( W) and zirconium dioxide (ZrO ₂ ) It may be made as a heating element comprising one or more selected from the group consisting of.

In the present embodiment, when the single crystal is grown in a vacuum atmosphere or inert gas atmosphere of the growth furnace 10, the first heater 41 made of porous graphite, the second heater 42 made of high density graphite, and molybdenum, tungsten or A third heater 43 made of high-density graphite having a polished surface may be used, and in place of the graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), Tungsten (W), zirconium dioxide (ZrO ₂ ), or mixtures thereof can be used as the material in porous, high density, or high density polished surfaces to suit the application.

However, when growing single crystals in the atmosphere of the growth furnace 10, the first heater 41 made of a porous ceramic composite material, the second heater 42 made of a high density ceramic composite material, and the high density ceramic polished surface A third heater 43 made of a composite material may be used, wherein graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), and zirconium dioxide (ZrO ₂ ) may be used as the ceramic composite material. ) And mixtures thereof may be used as a high-density material of porous, high density or surface polished to suit the application.

Here, the first to third heaters 41, 42, 43 as described above are preferably installed at least 3mm apart so that the reaction does not occur at a high temperature.

In particular, it is preferable that the second heater 42 is formed to have a thicker upper portion than the lower portion in order to give a temperature gradient to the growing single crystal and / or the melt of the single crystal raw material, which can grow into a ceramic single crystal of good quality. This is to control the temperature gradient of the condition.

In the present embodiment, the auxiliary heating unit 60 to heat the first to third heaters 41, 42, 43 and the crucible 20 of the main heating unit 30 as a microwave (micro-wave) It is for.

That is, the auxiliary heating unit 60 allows the raw materials in the main heating unit 30 and the crucible 20 to self-heat by microwaves.

The auxiliary heating unit 60 is configured on the upper side of the growth path 10, and includes a magnetron 61 for generating microwaves in the growth path 10.

The magnetron 61 is also referred to as a magnetron as a two-pole vacuum tube that oscillates microwaves in a magnetic field. The operation principle of the magnetron 61 is as follows.

Iii) Apply DC magnetic field externally.

Ii) Heat the cathode to a high temperature to make it ready for the release of hot electrons.

V) A DC high voltage is applied between the anode and the cathode.

V) hot electrons emitted from the cathode surface are accelerated toward the anode.

V) Hot electrons accelerated toward the anode are bent by a magnetic field to rotate around the cathode.

Iii) The microwaves and magnetron circuits rotating around the cathode resonate and generate microwaves.

The microwave rapidly vibrates molecules of the raw materials in the first to third heaters 41, 42, 43 and the crucible 20, and through the vibration frictional heat, the first to third heaters 41, 42, 43 and the crucible 20 induces self-heating of the raw materials.

Here, the magnetron 61 may be provided with a guide member (not shown in the drawing) which horizontally reflects the microwaves so that the distribution of the microwaves can be spread evenly throughout the growth path 10.

Meanwhile, a pyrometer 51 for measuring temperature may be installed in the growth furnace 10 constituting the crucible 20, the main heating unit 30, and the auxiliary heating unit 60 as described above. .

The pyrometer 51 is configured as an optical thermometer for measuring the light emitted from the second heater 42 of the main heating unit 30 and converting it into a temperature.

In addition, a probe rod 53 may be installed at an upper side of the growth furnace 10 to determine a melting state of raw materials or seed crystals in the crucible 20.

The probe rod 53 is made of a tungsten rod and the molten state of the raw material or seed crystal in the crucible 20 can be determined by dropping the tungsten rod toward the crucible 20 and measuring the drop length of the tungsten rod.

In the present embodiment, the heat exchange part 70 performs direct heat exchange with the seed crystals in the crucible 20, and serves to remove vibrations caused by rapid volume expansion occurring at high temperatures and to maintain a constant refrigerant temperature. .

The heat exchange part 70 includes a cooling copper rod 71 which is in contact with the lower side of the crucible 20 and coupled to the growth furnace 10, and the cooling copper rod 71 may be installed by fixing a refrigerant. Can be installed to move up and down, up and down.

In order to supply a coolant to the cooling copper rod, a coolant temperature control unit, a coolant auxiliary tank, a coolant distributor, a flow meter, and the like may be provided, wherein a coolant known as the coolant may be used without limitation, and more preferably, coolant may be used. Can be.

Meanwhile, in the present invention, the cooling copper rod 71 is not particularly limited to being installed up and down in a vertical direction, and the crucible 20 may be installed up and down in a vertical direction.

Therefore, in this embodiment, most of the heat radiated from the main heating unit 30 is introduced into the crystal through the wall of the crucible 20 and the melt surface, and most of the introduced heat is externally supplied through the cooling copper rod 71. To get out.

Here, the volume and shape of the cooling copper rod 71 has a great influence on the quality of the single crystal, and dominates the temperature distribution and temperature gradient in the single crystal, and therefore is not limited to any particular numerical value and shape in the present invention.

In addition, the cooling copper rod 71 may be provided with a molybdenum or tungsten cooling rod (not shown in the figure) that can withstand high temperatures, in particular in the case of sapphire single crystal manufacturing at 2050 ℃ or more.

In the present embodiment, the cooling unit 80 has a cooling chamber 81 which is installed on the outer wall of the growth furnace 10 and consists of a structure capable of supplying a coolant, preferably cooling water, to the cooling chamber 81. .

The cooling unit 80 includes a coolant temperature controller, a coolant auxiliary tank, a coolant distributor, a flow meter, and the like for supplying coolant to the cooling chamber 81 and the cooling copper rod 71.

Since the configuration of the cooling unit 80 is made of a cooling water supply device of a known technique well known in the art, a detailed description of the configuration will be omitted herein.

In the above, the cooling chamber 81 may be configured as a cooling method on the outer wall, the upper cover, and the lower cover of the growth furnace 10.

On the other hand, the single crystal growth apparatus 100 as described above is an electronic control unit (not shown in the drawing) for controlling the temperature, vacuum degree, supply power, vertical movement of the growth furnace cover, supply of cooling water, etc. in the growth furnace 10. It is configured externally, and this electronic control unit may include a recorder, a converter, and the like for recording temperature, vacuum degree, power supply, and the like.

A single crystal growth method according to another exemplary embodiment of the present invention includes the steps of (a) placing a seed crystal at the bottom of the crucible configured inside the heater; (B) filling a single crystal raw material on the seed crystal; (C) heating the heater and the single crystal raw material by using a microwave to form a uniform molten raw material; (D) cooling the seed crystals by using a heat exchanger provided under the crucible so that the seed crystals do not melt in parallel with step (c); (E) growing the uniform molten raw material from the seed crystal to a single crystal; And (f) growing the uniform molten raw material into single crystal by controlling a temperature gradient between the uniform molten raw material and the growing single crystal in parallel with step (e). have.

In the single crystal growth method, the heater and the single crystal raw material may self-heat by irradiating the microwaves.

In the single crystal growth method, the single crystal raw material may be any one selected from the group consisting of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon (Si), and gallium nitride (GaN).

In the single crystal growth method, the heater may include a first heater, a second heater, and a third heater that are sequentially installed outside the crucible.

In the single crystal growth method, the first to third heaters may include graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), and tungsten (W). And zirconium dioxide (ZrO ₂ ) It may include one or more selected from the group consisting of.

In the single crystal growth method, the crucible is graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide (ZrO). _It may comprise one or more selected from the group consisting of ₂ ).

Hereinafter, exemplary embodiments and operational effects according to the single crystal growth apparatus 100 of the present invention configured as described above will be described in detail.

In this embodiment, sapphire seed crystals 36 mm in diameter and 12 mm in height are placed on the bottom of the crucible 20 made of molybdenum so that the seed crystals and the cooling copper rods 71 are aligned, and 4 kg of alumina raw material 1 is loaded thereon. do.

Then, after covering and locking the lid (not shown) of the crucible 20, while covering the lid of the first heater, the second heater and the third heater of the main heating unit and locked the lid, After raising the temperature to 200 ° C. through the main heating unit 30, maintaining it for a certain time, and then vacuuming the interior of the growth furnace 10 to about 10 ⁻³ Torr through a vacuum composition unit (not shown). Let's do it.

Thereafter, the process of injecting and discharging an inert gas atmosphere such as Ar or N ₂ into the growth furnace 10 through a gas injection valve (not shown in the drawing) is repeated to increase the degree of vacuum in the growth furnace 10. Maintain about 10 ^-3 Torr.

In addition, the cooling water supplied to the cooling copper rod 71 is set to 5 l / min to 1900 ℃, the temperature program is set to 4 hours to 1900 ℃ and the temperature is raised, the seed crystal through the probe rod 53 at 1900 ℃ Determine the melting of and raise the seed crystals to a temperature in the range that does not melt, and maintain for 2 hours.

Here, the first heater 41 of the main heating unit 30 is made of porous graphite, buffers a sudden thermal shock and preserves the temperature in the crucible 20, the second heater 42 is made of high density graphite The high heat is supplied to the crucible 20 sufficiently, and the third heater 43 is made of high-density graphite polished on the surface, and the heat distribution can be kept constant and the temperature gradient can be controlled by blocking and dispersing radiant heat.

In the present embodiment, the microwaves are generated inside the growth path 10 through the magnetron 61 of the auxiliary heating unit 60.

Then, the microwave rapidly vibrates molecules of the raw material in the main heating unit 30 and the crucible 20 to induce self-heating of the fuel in the main heating unit 30 and the crucible 20 through the vibration frictional heat thereof.

In this embodiment, the temperature can be raised and maintained by the self-heating of the main heating unit 30 and the sapphire single crystal raw material alumina through microwaves, and the temperature can be raised more quickly and quickly by removing moisture and foreign matter. It is possible to reduce the temperature variation in the crucible 20 to minimize the heat convection phenomenon during the melting of the raw material can be melted uniformly.

As a result, in the present embodiment, since the fuel in the heating unit 30 and the crucible 20 is self-heated through the microwaves generated by the magnetron 61, the impurities in the growth furnace 10 are evaporated from solid to liquid. Except for a part of the seed crystal in the phase change process, the raw material in the crucible 20 is changed to the liquid phase, and in parallel with this, the seed crystal is cooled by using a heat exchanger provided at the bottom of the crucible so that the seed crystal is not melted. Let's do it.

In this embodiment, the cooling water is supplied to the cooling chamber 81 and the cooling copper rod 71 to decrease the temperature at a constant cooling rate (for example, 0.05 ° C./h).

Referring to FIG. 2, in the present embodiment, a sapphire single crystal that started to grow from seed crystals was obtained while a temperature gradient was generated inside the melt (liquid phase) during the cooling process described above.

3 to 7, X-ray rotation of the sapphire single crystal grown as described above, the sapphire single crystal was found to be uniformly excellent crystallinity, referring to Figure 8, the crystal orientation deviation in the (0001) direction Was + 0.06 ~ 0,07˚, and full width at half maximum (FWHM) value was 0.120 ~ 0.126, indicating good directionality. Etch Pit Density (EPD) was 1.57 X 10 ² pcs / cm ² , which was evaluated as good defect density.

X-ray diffraction ( XRD ) Experiment

Rigaku's X-ray diffractometer was used, CuKα (λ = 1.542) was used, and the scan rate was measured at 4˚ / min at 40KV and 30mA, and the diffraction beam range was 20˚ ~ 80˚ (2θ). The crystallinity of the ceramic crystals was investigated. The orientation measurement of single crystal growth was measured using the Laue method.

As described above, according to the single crystal growth apparatus 100 according to the exemplary embodiment of the present invention, by simultaneously heating the raw materials in the main heating unit 30 and the crucible 20 using microwaves, the moisture is initially increased. It is possible to secure the reaction stability in the crucible 20 through the removal.

In addition, in the present embodiment, a temperature gradient is arbitrarily formed according to the cross-sectional area, weight, and shape of the first to third heaters 41, 42, and 43 of the main heating unit 30 to adjust the growth rate of the single crystal. High quality single crystals can be grown economically.

In addition, in this embodiment, recrystallization occurs when the high purity (99.995) α-Al ₂ O ₃ powder is heated to 1850 ° C. using microwave, and there are no impurities and bubbles in the crystal and the particle size is also small. As the height can be lowered as much as possible, and the temperature rises, it can reduce the reactants at high temperature as well as low temperature to bring about stabilization in the furnace. And manufacturing costs can be lowered in terms of power costs.

In addition, in the present embodiment, by simultaneously heating the raw materials in the main heating unit 30 and the crucible 20 using microwaves, it is possible to eliminate the temperature deviation and the temperature gradient of the heater and the heated object, which are problems of the electric furnace and the high frequency furnace. It is possible to grow high quality single crystal by suppressing convection phenomenon of molten metal in the molten state as much as possible.

In addition, in the present embodiment, due to the simultaneous heating of the main heating unit 30 and the raw material, it is possible to reduce the manufacturing cost by significantly reducing the temperature rise time, it is possible to exhibit an economically excellent effect by reducing the power consumption.

In addition, in the present embodiment, the material, thickness, and shape of the first to third heaters 41, 42, and 43 constituting the main heating unit 30 are set differently to adjust the temperature in the hot-zone. It can be arbitrarily adjusted, and since the melting state of the seed crystal can be confirmed using the probe rod 53, the probability of failure of the sapphire single crystal can be significantly reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And it goes without saying that the invention belongs to the scope of the invention.

10... 11 to growth. Heat insulation felt
13 ... Gas inlet 20... Crucible
30 ... Main heating unit 41... First heater
42 ... Second heater 43... Third heater
51 ... Pyrometer 53... Probe rod
60 ... Auxiliary heating unit 61.. magnetron
70 ... . Heat exchanger 71. Cooling copper rod
80 ... Cooling unit 81... Cooling chamber

Claims (15)

Growth furnace constituting the insulation felt inside;
A crucible installed inside the thermal insulation felt, the seed crystal is located to accommodate the single crystal raw material;
A main heating unit configured at an outer side of the crucible and providing heat to the crucible;
An auxiliary heating unit mounted to the growth furnace and heating the single crystal raw material in the heating unit and the crucible as a microwave;
A heat exchanger configured at a lower side of the crucible and configured to exchange heat with the crucible; And
A cooling unit having a cooling chamber installed on an outer wall of the growth path and supplying a refrigerant to the cooling chamber;
Single crystal growth apparatus comprising a. The method according to claim 1,
The auxiliary heating unit,
Single crystal growth apparatus comprising a magnetron (magnetron) for generating a microwave inside the growth furnace. The method of claim 2,
The single crystal raw material in the main heating unit and the crucible is self-heating by irradiating the microwaves. The method of claim 3,
The single crystal raw material is any one selected from the group consisting of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon (Si) and gallium nitride (GaN). The method according to claim 1,
The main heating unit,
Single crystal growth apparatus comprising a single or a plurality of heaters sequentially installed on the outside of the crucible. The method according to claim 1,
The heater is a single crystal growth apparatus, characterized in that the thickness of the top is greater than or equal to the thickness of the bottom. The method according to claim 1,
The main heating unit,
Single crystal growth apparatus characterized in that it comprises one or more selected from the group consisting of a first heater, a second heater and a third heater sequentially installed on the outside of the crucible. The method of claim 7, wherein
The first heater, the second heater, or the third heater is graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide Single crystal growth apparatus comprising at least one selected from the group consisting of (ZrO ₂ ). The method according to claim 1,
The crucible is 1 selected from the group consisting of graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide (ZrO ₂ ). Single crystal growth apparatus comprising more than one species. The method according to claim 1,
The growth path is a single crystal growing apparatus, characterized in that the single crystal is grown in any one atmosphere selected from the group consisting of a vacuum atmosphere, an inert gas atmosphere and an atmospheric atmosphere. (A) placing seed crystals at the bottom of the crucible configured inside the heater;
(B) filling a single crystal raw material on the seed crystal;
(C) heating the heater and the single crystal raw material by using a microwave to form a uniform molten raw material;
(D) cooling the seed crystals by using a heat exchanger provided under the crucible so that the seed crystals do not melt in parallel with step (c);
(E) growing the uniform molten raw material from the seed crystal to a single crystal; And
(F) growing the uniform molten raw material into single crystal by controlling a temperature gradient between the uniform molten raw material and the growing single crystal in parallel with step (e);
Single crystal growth method comprising a. The method of claim 11, wherein
And the heater and the single crystal raw material self-heat by irradiating the microwaves. The method of claim 11, wherein
The heater is a single crystal growth method characterized in that it comprises one or more selected from the group consisting of a first heater, a second heater and a third heater that is sequentially installed on the outside of the crucible. The method of claim 13,
The first heater, the second heater, or the third heater is graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide Single crystal growth method characterized in that it comprises one or more selected from the group consisting of (ZrO ₂ ). The method of claim 11, wherein
The crucible is 1 selected from the group consisting of graphite, silicon carbide (SiC), pyrolytic boron nitride (PBN), molybdenum (Mo), tungsten (W) and zirconium dioxide (ZrO ₂ ). A single crystal growth method comprising more than one species.

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