JP2015051888A - Apparatus for making single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for making a single crystal which does not have complex structure and whose footprint is suppressed.SOLUTION: The apparatus for making a single crystal is an apparatus for growing a single crystal 24 by subliming a raw material 21 and includes: a growth vessel 2 having an interior space 50 extending to a vertical direction; a sublimation vessel 14 disposed in the interior space of the growth vessel; a feeding device 10 which is disposed above the sublimation vessel and can continuously feed the raw material to the sublimation vessel; a crystal growth part 23 disposed in the interior space of the growth vessel; and flow devices 30 and 40 which flow gas in the interior space so as to pass through the crystal growth part.

Description

  The present invention relates to a single crystal manufacturing apparatus.

  In recent years, research and development related to nitride semiconductors have made remarkable progress, starting with the success of blue light-emitting devices using gallium nitride (GaN) -based semiconductors. For example, aluminum nitride (AlN) single crystal has features of high thermal conductivity and high insulation, and is expected as an AlGaN-based semiconductor substrate that is a mixed crystal of AlN and GaN having a close lattice constant. As a method for producing an AlN single crystal, there are a flux method in a solution method, MOVPE in a vapor phase method, hydride vapor phase epitaxy (HVPE), a sublimation method, and the like. Among these, the sublimation method is a powerful method for producing a bulk crystal because the growth rate is generally high. The sublimation method is a method in which a crystal grows by sublimating AlN as a raw material and transporting and condensing it to a seed crystal fixed in a growth part that is a temperature range lower than the sublimation temperature.

  The growth of the sublimation method is growth in a closed system, and is a batch type crystal growth method. For this reason, crystals can be grown only in an amount less than or equal to the weight of the filled raw material, and the length of crystals that can be grown is limited. Therefore, in order to enable the raw material input from the outside and continuous growth, open-type sublimation growth without sealing the growth vessel has been studied. For example, Patent Document 1 discloses a single crystal manufacturing apparatus in which a growth vessel is formed in an L shape including a vertical portion extending in the vertical direction and a horizontal portion connected below the vertical portion. In the growth container having this configuration, the seed crystal is arranged above the vertical part, the raw material container is arranged on the end part opposite to the connecting part with the vertical part in the horizontal part, and the raw material hopper provided above the raw material container The feed can be continuously fed from the feeder.

JP 2010-150111 A

However, the following problems exist in the conventional technology as described above.
In the manufacturing apparatus described above, the growth vessel is formed in an L shape, and if a raw material hopper and a feeder are included, the device configuration becomes a concave shape, resulting in a problem that the apparatus becomes complicated and the installation area increases. .

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide a single crystal manufacturing apparatus that does not complicate the structure and can reduce the installation area.

  The present invention is a single crystal manufacturing apparatus for growing a single crystal by sublimating a raw material, a growth vessel having an internal space extending in a vertical direction, and a sublimation vessel provided in the internal space of the growth vessel; A supply device provided above the sublimation vessel and capable of continuously supplying the raw material to the sublimation vessel; a crystal growth unit provided in the internal space of the growth vessel; and a gas in the internal space for growing the crystal A single crystal manufacturing apparatus comprising: a flow device for flowing so as to pass through the portion.

  According to the single crystal manufacturing apparatus of the present invention, the raw material is continuously supplied from above to the sublimation container provided in the internal space from the supply apparatus. The gas in which the raw material is sublimated in the sublimation vessel rises, but the flow device causes the gas in the internal space to flow, so that the sublimation gas passes through the crystal growth portion. And a raw material precipitates in a crystal growth part, and grows as a single crystal. Therefore, in the present invention, while the supply device can continuously supply the raw material to the sublimation container from above, the rising sublimation gas can flow into the crystal growth part together with the gas in the internal space and grow as a single crystal. Become. Therefore, in the present invention, it is not necessary to dispose the crystal growth part above the sublimation vessel, and the supply device can be arranged above the sublimation vessel, so that the growth vessel has an internal space extending in the vertical direction. It is possible to reduce the installation area without complicating the structure.

Moreover, this invention is a single-crystal manufacturing apparatus with which a supply apparatus drops a raw material freely and supplies it to a sublimation container.
According to the single crystal manufacturing apparatus of the present invention, it is not necessary to set a supply path including the horizontal direction, and the raw material can be easily supplied to the sublimation container.

  The present invention also provides a pressure control in which the supply device controls the pressure in the raw material container according to the pressure of the growth container by adjusting the amount of gas introduced by the raw material container, the gas introduction part for introducing gas into the raw material container A single crystal manufacturing apparatus.

  According to the single crystal manufacturing apparatus of the present invention, the pressure in the raw material container can be easily made equal to the pressure in the growth container, and stable single crystal manufacturing can be realized.

The present invention is also a single crystal manufacturing apparatus comprising a supply nozzle that is inserted into an internal space and opens above the sublimation container, and supplies a raw material in the raw material container to the sublimation container.
According to the single crystal manufacturing apparatus of the present invention, the raw material in the raw material container can be easily supplied to the sublimation container via the supply nozzle.

Further, the present invention provides a gas introducing unit provided above the sublimation container in the internal space, and a gas discharging unit provided on the opposite side of the gas introducing unit across the crystal growth unit in the internal space. A single crystal production apparatus comprising:
According to the single crystal manufacturing apparatus of the present invention, a gas flow from the gas introduction part to the gas discharge part is formed in the internal space. Therefore, in this invention, the sublimation gas which rose from the sublimation container flows toward a gas discharge part with said gas. Since the crystal growth part is provided in the middle from the gas introduction part to the gas discharge part, the sublimation gas flowing together with the gas passes through the crystal growth part and can be grown as a single crystal.

The present invention also provides a partition wall that partitions the internal space into a first space in which the sublimation container and the gas introduction unit are disposed, and a second space in which the crystal growth unit and the gas discharge unit are disposed, and the partition wall An apparatus for producing a single crystal, comprising: an introduction part that is provided at a position facing the crystal growth part and introduces the gas in the first space into the second space toward the crystal growth part.
According to the single crystal manufacturing apparatus of the present invention, the gas in the first space containing the sublimation gas is intensively introduced into the second space from the introduction part. Since the crystal growth part is provided at a position opposite to the introduction part in the second space, the sublimation gas introduced from the introduction part flows intensively toward the crystal growth part, and effectively singles. Crystal growth can be performed.

In addition, the present invention is the single crystal manufacturing apparatus characterized in that the crystal growth part is disposed below the sublimation vessel.
According to the single crystal manufacturing apparatus of the present invention, the sublimation container, the supply device, and the crystal growth part can be arranged along the vertical direction in the internal space, and the installation area can be further reduced.

  In the present invention, since the supply device can continuously supply the raw material to the sublimation vessel from above, the rising sublimation gas can flow into the crystal growth portion together with the gas in the internal space to grow as a single crystal. It is not necessary to dispose the crystal growth part above the sublimation container, the supply device can be disposed above the sublimation container, and the growth container has a structure having an internal space extending in the vertical direction. However, the installation area can be reduced without increasing the complexity.

It is the schematic block diagram which showed typically an example of the single crystal manufacturing apparatus 1 which manufactures a nitride single crystal. It is the schematic block diagram which showed typically an example of the single crystal manufacturing apparatus 1 of another form.

Hereinafter, an embodiment of a single crystal manufacturing apparatus of the present invention will be described with reference to FIGS. 1 and 2.
Here, an example of manufacturing an aluminum nitride single crystal will be described.

FIG. 1 is a schematic configuration diagram schematically showing an example of a single crystal manufacturing apparatus 1 for manufacturing a nitride single crystal by a sublimation method.
The single crystal manufacturing apparatus 1 includes a growth container 2, a susceptor 3, a heating device 7, a supply device 10, a raw material container (sublimation container) 14, a gas introduction part 30, and a gas discharge part 40. The growth vessel 2 and the heating device 7 are surrounded by a chamber 8.

  The supply device 10 can continuously supply the raw material 21 to the raw material container 14, and includes a raw material hopper (raw material container) 12 having a carry-in port 12 </ b> A and containing the raw material 21, and the raw material hopper 12. A feeder 13 for supplying the raw material 21, a supply nozzle 11 provided below the feeder 13, and a shutter 12 </ b> B provided in the middle of the supply nozzle 11 are configured.

  A gas introduction part 15 such as nitrogen gas and a pressure regulating valve (pressure control part) 16 are provided on the upper side of the raw material hopper 12, and the internal pressure of the raw material hopper 12 is controlled to be equal to the internal pressure of the growth vessel 2. It can be done.

  The growth vessel 2 has an internal space 50 extending in the vertical direction. At the top of the growth vessel 2, the lower end of the supply nozzle 11 is inserted into the internal space 50, and the opening of the supply nozzle 11 is disposed above the raw material vessel 14. The susceptor 3 is disposed below the raw material container 14 in the internal space 50. As shown in FIG. 1, the supply nozzle 11, the raw material container 14, and the susceptor 3 are disposed on a straight line along the axial direction of the internal space 50.

  The susceptor 3 is configured such that a nitride single crystal (aluminum nitride single crystal) 24 grows on a seed substrate (crystal growth portion) 23 attached to the upper surface. The susceptor 3 is a plate made of graphite or the like, and the seed substrate 23 for crystal growth is, for example, a 6-H—SiC or aluminum nitride single crystal plate having a diameter of 2 inches.

  The growth vessel 2 is provided with a heating device 7 using a resistance heating method for heating the raw material 21, the susceptor 3, and the seed substrate 23 arranged in the growth vessel 2. Such a heating device 7 is not particularly limited, and a conventionally known device can be used. For example, carbon, tungsten, or the like can be used as the heater material.

  The growth container 2 includes a partition wall 20 that partitions the internal space 50 into a first space 2A and a second space 2B that are divided in the vertical direction. In the first space 2A, the lower end side of the supply nozzle 11 and the raw material container 14 are arranged. The susceptor 3 that supports the seed substrate 23 is disposed in the second space 2B. Further, a nozzle wall (introducing portion) 22 that introduces the gas in the first space 2 </ b> A toward the seed substrate 23 into the second space 2 </ b> B is provided at a position facing the seed substrate 23 in the partition wall 20.

  The gas introduction unit 30 introduces nitrogen gas as a gas into the internal space 50 of the growth vessel 2, and includes an introduction port 31 and a nitrogen gas supply source 32. The introduction port 31 is provided at a position where nitrogen gas can be introduced above the raw material container 14.

  The gas discharge unit 40 discharges the gas in the internal space 50 of the growth vessel 2 and includes an exhaust port 41 and an exhaust device 42 such as an exhaust pump. The exhaust port 41 is provided at the bottom of the growth vessel 2 on the opposite side of the introduction port 31 with the seed substrate 23 sandwiched in the vertical direction. The gas introduction part 30 and the gas discharge part 40 function as a flow device for causing the gas in the internal space 50 of the growth vessel 2 to flow (details will be described later).

  In the method for producing an aluminum nitride single crystal, aluminum nitride powder is used as a raw material. By heating this powder in the raw material container 14, a sublimation gas of aluminum nitride can be generated. Crystals are grown on the seed substrate 23 in the growth vessel 2 by flowing the aluminum nitride gas and nitrogen gas generated in this way to the seed substrate 23.

Then, the manufacturing method of the aluminum nitride single crystal 24 using said single crystal manufacturing apparatus 1 is demonstrated.
First, the inlet 12A provided in the raw material hopper 12 is opened, and the raw material 21 of aluminum nitride powder is accommodated in the raw material hopper 12, and then the inlet 12A is closed to seal the raw material hopper 12.

Next, the shutter 12 </ b> B is opened, and the raw material 21 is introduced from the feeder 13 into the internal space 50 of the growth vessel 2 through the supply nozzle 11, is freely dropped, and is supplied to the raw material vessel 14.
At this time, since the internal pressure of the raw material hopper 12 is controlled to be equal to the pressure of the internal space 50 of the growth vessel 2, it is possible to avoid problems caused by the pressure difference when supplying the raw material.

  Subsequently, after the gas in the internal space 50 is exhausted from the exhaust port 41 by the operation of the exhaust device 42, the nitrogen gas from the nitrogen gas supply source 32 is introduced into the internal space 50 of the growth vessel 2 through the introduction port 31 and the pressure is increased. Adjust. The pressure here can be set to 1 to 760 Torr, more preferably 10 to 500 Torr.

And the raw material container 14, the susceptor 3, and the seed board | substrate 23 with which the raw material 21 was distribute | arranged using the heating apparatus 7 are heated.
Here, the temperature in the raw material container 14 can be set to 1700-2250 degreeC, More preferably, 1750-2200 degreeC. Moreover, the temperature of the seed substrate 23 which is a growth part can be set to 1700-2300 degreeC, More preferably, it can be set to 1800-2250 degreeC. At this time, the temperature near the raw material container 14 is set to be higher than the temperature near the seed substrate 23.

  Further, during heating by the heating device 7, the inside of the growth vessel 2 is supplied by supplying nitrogen gas from the introduction port 31 to the internal space 50 of the growth vessel 2 while exhausting the gas in the growth vessel 2 from the exhaust port 41. The gas pressure and flow rate in the space 50 are adjusted appropriately.

  As described above, in the internal space 50, the gas pressure is adjusted by supplying nitrogen gas from the introduction port 31 while exhausting the gas in the growth vessel 2 from the exhaust port 41. A gas flow toward the exhaust port 41 is formed. Therefore, the aluminum nitride gas generated by heating the raw material 21 in the raw material container 14 flows toward the exhaust port 41 together with the nitrogen gas supplied from the introduction port 31.

  Specifically, the aluminum nitride gas generated in the first space 2A and the nitrogen gas supplied to the first space 2A are intensively introduced into the second space 2B from the opening surrounded by the nozzle wall 22, and the susceptor 3 After passing through the seed substrate 23 supported by the air, it is discharged from the exhaust port 41. When the aluminum nitride gas and the nitrogen gas pass through the seed substrate 23, they are deposited on the seed substrate 23 and grow as crystals, thereby becoming an aluminum nitride single crystal 24.

  In the present embodiment, the raw material 21 can be appropriately supplied from the feeder 13 to the raw material container 14 through the supply nozzle 11 during the growth of the single crystal. The supply of the raw material 21 is, for example, intermittently free of the raw material 21 from the supply nozzle 11 to the raw material container 14 by opening the shutter 12B after supplying a predetermined amount of the raw material 21 from the feeder 13 with the shutter 12B closed. A method of dropping, a method of continuously free-falling from the feeder 13 through the supply nozzle 11 with the shutter 12B opened after the internal pressure of the raw material hopper 12 and the pressure of the internal space 50 become equal, etc. It is possible to take

  By the above method, the nitrogen gas supplied from the introduction port 31 and the aluminum nitride gas generated in the raw material container 14 can be continuously and stably flowed toward the seed substrate 23, and the seed substrate 23 The aluminum nitride single crystal 24 grown on the surface to be deposited can be continuously grown semi-permanently. Thereby, the diameter of the aluminum nitride single crystal 24 can be increased by prolonging the crystal growth time.

[Example]
In the single crystal manufacturing apparatus 1 shown in FIG. 1, the seed substrate 23 is made of AlN having a diameter of 35 mm, the heating apparatus 7 and the growth vessel 2 are made of tungsten, and the crystal growth conditions are a pressure of 100 Torr, a growth time of 100 hours, and nitrogen gas. When a single crystal was manufactured at a flow rate of 400 sccm, a temperature of the raw material container 14 of 2270 ° C., and a temperature of the seed substrate 23 of 2150 ° C., an AlN single crystal having a length of about 30 mm was obtained.
When a single crystal was manufactured with a batch manufacturing apparatus having a conventional structure under the same conditions, an AlN single crystal having a length of about 5 mm was obtained.

  As described above, in the present embodiment, the aluminum nitride gas generated in the raw material container 14 is caused to flow toward the exhaust port 41 together with the nitrogen gas supplied from the introduction port 31 to pass through the seed substrate 23. There is no need to dispose the seed substrate 23 above the material container 14. Therefore, in the present embodiment, the supply nozzle 11 is arranged above the raw material container 14 to enable continuous supply of the raw material 21, and the supply nozzle 11, the raw material container 14 and the seed substrate 23 are arranged in the vertical direction. It can be arranged in the extended internal space 50. Therefore, in this embodiment, it is possible to simplify the apparatus configuration and reduce the installation area of the single crystal manufacturing apparatus 1 while realizing continuous single crystal growth. In addition, in this embodiment, since the raw material 21 is freely dropped and supplied to the raw material container 14, it is not necessary to separately provide a device for transporting the raw material 21, contributing to downsizing and cost reduction of the device. it can. In particular, in this embodiment, since the seed substrate 23 is disposed below the raw material container 14, the installation area of the single crystal manufacturing apparatus 1 can be minimized.

  Further, in the present embodiment, the internal space 50 is vertically divided into the first space 2A and the second space 2B by the partition wall 20, and the nozzle wall 22 is provided on the partition wall 20 so as to face the seed substrate 23. Therefore, the aluminum nitride gas generated in the raw material container 14 effectively passes through the seed substrate 23, and single crystal growth can be performed efficiently.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, the seed substrate 23 is disposed below the raw material container 14 and the aluminum nitride gas and the nitrogen gas are flowed downward from above, but the introduction port 31 is located above the raw material container 14. If the exhaust port 41 is disposed on the opposite side of the introduction port 31 with the seed substrate 23 interposed therebetween, the present invention is not limited to this. As shown in FIG. It is good also as a structure which arrange | positions upwards at one side of a horizontal direction, arrange | positions the exhaust port 41 on the other side of a horizontal direction, and flows aluminum nitride gas and nitrogen gas along a horizontal direction.

  Moreover, although the case where an aluminum nitride single crystal is manufactured as a single crystal is illustrated in the above embodiment, the single crystal manufactured by the single crystal manufacturing apparatus 1 may be any sublimable single crystal, for example, An SiC single crystal, a GaN single crystal, etc. are mentioned. These powder crystals are used as raw materials for these single crystals.

  The single crystal obtained by the present invention can be used for growth substrates used for forming deep ultraviolet to blue light emitting diodes, laser diodes, and the like, and substrates for high voltage power devices, high frequency electronic devices and the like.

  DESCRIPTION OF SYMBOLS 1 ... Single-crystal manufacturing apparatus, 2 ... Growth container, 2A ... 1st space, 2B ... 2nd space, 10 ... Supply apparatus, 11 ... Supply nozzle, 12 ... Raw material hopper (raw material container), 14 ... Raw material container (sublimation container) , 15 ... Gas introduction part, 16 ... Pressure regulating valve (pressure control part), 20 ... Partition wall, 21 ... Raw material, 22 ... Nozzle wall (introduction part), 23 ... Seed substrate (crystal growth part), 24 ... Nitriding Single crystal (single crystal), 30 ... gas introduction part (flow device), 40 ... gas discharge part (flow device), 50 ... internal space

Claims (7)

A single crystal manufacturing apparatus for growing a single crystal by sublimating a raw material,
A growth vessel having an interior space extending vertically;
A sublimation container provided in the internal space of the growth container;
A supply device provided above the sublimation container and capable of continuously supplying the raw material to the sublimation container;
A crystal growth part provided in the internal space of the growth vessel;
A flow device for flowing the gas in the internal space so as to pass through the crystal growth part;
An apparatus for producing a single crystal, comprising:   The single-crystal manufacturing apparatus according to claim 1, wherein the supply device freely drops the raw material and supplies the raw material to the sublimation container.   The supply device includes a raw material container, a gas introduction unit that introduces gas into the raw material container, and a pressure control that controls the pressure in the raw material container according to the pressure of the growth container by adjusting the amount of the gas introduced The single crystal manufacturing apparatus according to claim 1, wherein the single crystal manufacturing apparatus includes a unit.   4. The single crystal according to claim 3, wherein the supply device includes a supply nozzle that is inserted into the internal space and opens above the sublimation container, and supplies a raw material in the raw material container to the sublimation container. manufacturing device. The flow device includes a gas introduction unit provided above the sublimation container in the internal space;
5. The single crystal production according to claim 1, further comprising: a gas discharge portion provided on the opposite side of the gas introduction portion with the crystal growth portion interposed therebetween in the internal space. apparatus. A partition wall that divides the internal space into a first space in which the sublimation container and the gas introduction unit are disposed, and a second space in which the crystal growth unit and the gas discharge unit are disposed;
6. The partition wall is provided at a position facing the crystal growth part, and is provided with an introduction part for introducing the gas in the first space into the second space toward the crystal growth part. Single crystal manufacturing equipment.   The single crystal manufacturing apparatus according to claim 1, wherein the crystal growth unit is disposed below the sublimation container.

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