AlN crystal growth apparatus and AlN crystal growth method

Abstract

The present invention provides an AlN crystal growth apparatus and AlN crystal growth method capable of stably growing high-quality AlN single crystals with high crystallinity. [Solution] The system comprises a reaction tube 12, an AlCl3 bottle 31 containing small pieces of solid aluminum chloride, a flow rate controller capable of adjusting the flow rate of the gas supplied to the AlCl3 bottle, an AlCl3 supply pipe 21 that supplies AlCl3 gas from the AlCl3 bottle to the reaction tube, a nitrogen raw material supply pipe 23 that supplies nitrogen raw material gas to the reaction tube, an absorbance meter 40 provided in the AlCl3 supply pipe that measures the absorbance of the AlCl3 gas supplied to the reaction tube, and a control unit that controls the flow rate controller to adjust the flow rate of the gas supplied to the reaction tube based on the absorbance measurement value and supplies AlCl3 gas to the reaction tube.

Description

Technical Field

[0001] The present invention relates to an AlN crystal growth apparatus and an AlN crystal growth method, and more particularly to an AlN crystal growth apparatus and an AlN crystal growth method for growing AlN crystals by a hydride vapor phase growth method.

[0002] Aluminum nitride (AlN) having a large bandgap is being researched and developed as a material for short-wavelength semiconductor light-emitting devices and semiconductor devices, particularly semiconductor light-emitting devices in the deep ultraviolet region. In addition, it has excellent thermal conductivity and high electrical insulation, and is expected as an electronic device material.

[0003] In addition, research and development of the hydride vapor phase growth method as a method for growing bulk crystals and single crystal substrates of aluminum nitride is underway.

[0004] For example, Patent Document 1 discloses a hydride vapor phase growth apparatus in which aluminum chloride gas obtained by heating and sublimating or vaporizing anhydrous aluminum chloride and NH3 gas are reacted by the hydride vapor phase growth method to grow AlN crystals on a substrate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, conventionally, when growing an AlN single crystal by the hydride vapor phase growth method using AlCl3 gas generated by sublimation of solid aluminum chloride (AlCl3), it has been difficult to stably supply the AlCl3 gas and grow an AlN single crystal having high crystallinity.

[0007] The present invention has been made in view of the above-mentioned points, and aims to provide an AlN crystal growth apparatus and an AlN crystal growth method that can stably grow high-quality AlN single crystals with high crystallinity using solid aluminum chloride (AlCl3).

[0008] The AlN crystal growth apparatus according to one embodiment of the present invention is A reaction tube and An AlCl3 bottle containing small pieces of solid aluminum chloride, A flow controller capable of adjusting the flow rate of the gas supplied to the AlCl3 bottle, An AlCl3 supply tube that supplies AlCl3 gas from the AlCl3 bottle to the reaction tube, A nitrogen raw material supply pipe for supplying nitrogen raw material gas to the reaction tube, An absorbance meter provided in the AlCl3 supply tube for measuring the absorbance of the AlCl3 gas supplied to the reaction tube, A control unit that controls the flow rate controller to adjust the flow rate of the supplied gas based on the absorbance measurement value obtained by the absorbance meter, and supplies the AlCl3 gas to the reaction tube, It has.

[0009] Another embodiment of the present invention is an AlN crystal growth method, A reaction tube and An AlCl3 bottle containing small pieces of solid aluminum chloride, A flow controller capable of adjusting the flow rate of the gas supplied to the AlCl3 bottle, An AlCl3 supply tube that supplies AlCl3 gas from the AlCl3 bottle to the reaction tube, An AlN crystal growth apparatus comprising a nitrogen raw material supply pipe for supplying nitrogen raw material gas to the reaction tube, and an AlN crystal growth apparatus, wherein the method for growing AlN crystals is provided, While measuring the absorbance of the AlCl3 gas supplied to the reaction tube, the flow rate of the supplied gas is adjusted based on the measured absorbance to supply the AlCl3 gas to the reaction tube. Perform AlN single crystal growth. [Brief explanation of the drawing]

[0010] [Figure 1] It is a diagram schematically showing a hydride vapor phase growth apparatus which is an AlN crystal growth apparatus according to one embodiment of the present invention. [Figure 2A] It is a flowchart showing a sequence during growth standby. [Figure 2B] It is a flowchart showing an execution sequence of crystal growth. [Figure 3] It is a graph showing the absorbance of a mixed gas (Al raw material gas) of AlCl3 gas from an AlCl3 bottle and dilution N2 gas with respect to the flow rate of feed gas N2 gas. [Figure 4] It is a graph showing the absorbance of the Al raw material gas with respect to the feed time of feed gas N2 gas to the AlCl3 bottle. [Figure 5] It is a diagram showing the XRC full width at half maximum of a grown crystal when crystal growth is started at timings A and B shown in FIG. 4 for the cases where the growth plane is the (10-11) plane and the (0002) plane. [Figure 6] It is a microscopic image of the surface of an AlN growth layer when crystal growth is started before the absorbance of AlCl3 gas is stabilized (point A in FIG. 4) and after stabilization (point B in FIG. 4). [Figure 7] It is a diagram schematically showing the change rate of absorbance depending on the size of solid AlCl3 granules.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described, but these may be appropriately modified and combined. Also, in the following description and the accompanying drawings, substantially the same or equivalent parts will be described with the same reference numerals.

[0012] [First Embodiment]

[0013] (1) Configuration of AlN Crystal Growth Apparatus FIG. 1 is a diagram schematically showing a hydride vapor phase growth apparatus 10 which is an AlN crystal growth apparatus according to one embodiment of the present invention.

[0014] The hydride vapor phase growth apparatus 10 includes a reaction furnace 11 including a reaction tube 12, an exhaust unit 13, a heater 14, and supply pipes 21, 22, 23, 24, a gas supply unit 30, and a growth control unit 50. The reaction furnace 11 is configured as a horizontal furnace in which a raw material gas and a carrier gas are supplied horizontally.

[0015] The reaction tube 12 is made of, for example, quartz. A susceptor 15 on which a growth substrate 16 is placed is provided inside the reaction tube 12. For the growth substrate 16, an AlN substrate grown by, for example, the physical vapor transport (PVT) method is used.

[0016] The susceptor 15 and the growth substrate 16 are heated to the crystal growth temperature by the heater 14. The heater 14 is an induction heating type heater, but is not limited thereto. A heater such as a resistance heating type or a lamp heating type may be used.

[0017] Aluminum chloride (AlCl3) gas, which is an Al raw material gas, is supplied from the gas supply unit 30 to the supply pipe 21 (hereinafter also referred to as the AlCl3 supply pipe 21). Ammonia (NH3) gas, which is a nitrogen raw material gas, is supplied to the nitrogen raw material supply pipe 23. Further, hydrogen (H2) gas, which is a carrier gas, is supplied to the supply pipe 22, and nitrogen (N2) gas, which is a carrier gas, is supplied to the supply pipe 24.

[0018] The gases supplied from the AlCl3 supply pipe 21 and the supply pipes 22 to 24 flow horizontally in the reaction tube 12, and an AlN growth layer EP (AlN-HVPE layer) is formed on the growth substrate 16 heated to the growth temperature.

[0019] The gas supply unit 30 is provided with an AlCl3 bottle 31, which is a solid aluminum chloride container. Solid aluminum chloride (AlCl3) 31S is contained in the AlCl3 bottle 31. More specifically, solid AlCl3 in the form of powder, granules, flakes or pellets is stored in the AlCl3 bottle 31. In this specification, solid AlCl3 in these forms is collectively referred to as flaky solid AlCl3.

[0020] The N2 gas supplied to the AlCl3 bottle 31 comes from a nitrogen (N2) cylinder (not shown). The N2 gas is regulated by a mass flow controller (MFC) 32 and supplied to the inlet port 31A of the AlCl3 bottle 31 via piping 34. The sublimated AlCl3 gas is then supplied from the outlet port 31B of the AlCl3 bottle 31 to the AlCl3 supply pipe 21. In other words, AlCl3 gas whose flow rate is controlled by the MFC 32 is supplied to the AlCl3 supply pipe 21.

[0021] Furthermore, dilution N2 gas, whose flow rate is controlled by the MFC 33, is supplied to the AlCl3 supply pipe 21 via piping 36 (dilution gas supply pipe). As described above, the flow path of the AlCl3 gas (Al raw material gas) diluted with N2 gas is switched by the switching valve 37.

[0022] More specifically, the switching valve 37 is located in the middle of the AlCl3 supply pipe 21, closer to the reaction tube 12 than the absorbance meter 40, and switches between supplying the AlCl3 gas supplied via the AlCl3 supply pipe 21 to the reaction tube 12 or exhausting it to the exhaust section 13.

[0023] In other words, during crystal growth, the switching valve 37 introduces the AlCl3 gas flowing through the AlCl3 supply pipe 21 into the reaction tube 12. When growth is on hold, the valve 37 switches the flow path of the AlCl3 gas flowing through the AlCl3 supply pipe 21, bypassing it to the pipe 38, and the AlCl3 gas is exhausted to the exhaust section 13 via the pipe 38.

[0024] Ammonia (NH3) gas, which is the nitrogen raw material gas (N raw material gas), is introduced into the reaction tube 12 via the nitrogen raw material supply pipe 23. N2 gas, which is the carrier gas, is introduced into the reaction tube 12 via the supply pipe 22. H2 gas, which is the carrier gas, is introduced into the reaction tube 12 via the supply pipe 24.

[0025] NH3 gas is introduced into the reaction tube 12 or exhausted from the exhaust section 13 by switching a switching valve 23V located on the nitrogen raw material supply pipe 23. Carrier gas (N2 gas) is introduced into the reaction tube 12 or exhausted from the exhaust section 13 by switching a switching valve 22V located on the supply pipe 22. Carrier gas (H2 gas) is introduced into the reaction tube 12 or exhausted from the exhaust section 13 by switching a switching valve 24V located on the supply pipe 24.

[0026] The growth control unit 50 controls crystal growth by transmitting control signals CS to the MFC 32, MFC 33, switching valve 37, and switching valves 22V, 23V, and 24V. The control signals CS include various signals related to crystal growth. The growth control unit 50 may also be configured to receive and control various signals related to crystal growth from the components of the hydride vapor phase growth apparatus 10, such as the MFCs and switching valves mentioned above.

[0027] An absorbance meter 40 using Fourier transform infrared spectroscopy (FT-IR) is installed in the AlCl3 supply pipe 21 leading to the switching valve 37. The absorbance meter 40 has an FT-IR gas cell 41, an FT-IR light source 42, and an FT-IR photodetector 43.

[0028] The absorbance meter 40 measures the absorbance of the AlCl3 gas supplied to the reaction tube 12 via the AlCl3 supply tube 21 in response to the control signal CS from the growth control unit 50. Specifically, the absorbance meter 40 measures the absorbance of the mixed gas (Al raw material gas) of AlCl3 gas from the AlCl3 bottle 31 and dilution N2 gas, and obtains the absorbance measurement value ABS.

[0029] More specifically, the absorbance meter 40 irradiates the Al raw material gas in the FT-IR gas cell 41 with infrared light (IR) from the FT-IR light source 42, and measures the absorbance of the Al raw material gas from the infrared absorption spectrum obtained by the FT-IR photodetector 43. Specifically, the absorbance meter 40 has a gas cell with ZnSe as the window material, for example, 624 cm⁻¹. -1 The concentration of AlCl3 gas is measured using the absorption of the wavenumber.

[0030] The measured value signal MS, which shows the absorbance measurement value ABS of the obtained Al raw material gas, is sent to the growth control unit 50. Based on the measured value signal MS, the growth control unit 50 sends a control signal CS to the MFC 32 to adjust the flow rate of N2 gas (supply gas) supplied to the AlCl3 bottle 31. The growth control unit 50 is also configured to send a control signal CS to the MFC 33 based on the measured value signal MS to adjust the flow rate of N2 gas for dilution.

[0031] (2) Crystal growth sequence Figure 2A is a flowchart showing the sequence before crystal growth (while waiting for growth). Figure 2B is a flowchart showing the execution sequence of crystal growth.

[0032] The crystal growth method for AlN single crystals will be described below with reference to Figures 2A and 2B. The sequence during growth standby and the crystal growth execution sequence are controlled by the growth control unit 50. Although the sequence during growth standby and the crystal growth execution sequence are shown as separate sequences, they are executed sequentially.

[0033] In the following, the switching valves 37 and 23V described above will be collectively referred to as the crystal growth furnace valves. By switching the crystal growth furnace valves to "open" (ON), AlCl3 gas (Al raw material gas) and ammonia (NH3) gas are introduced into the reaction tube 12, and by switching them to "closed" (OFF), these gases are exhausted from the exhaust section 13.

[0034] (Step S11) First, the crystal growth furnace valve is turned OFF, and the Al raw material gas (AlCl3 gas) and NH3 gas (Group V raw material gas) are exhausted from the exhaust section 13.

[0035] (Step S12) Next, adjust the AlCl3 bottle 31 so that it reaches the set temperature.

[0036] (Step S13) A predetermined flow rate (for example, the flow rate during the previous growth) of N2 gas is introduced into the AlCl3 bottle 31 to sublimate the solid aluminum chloride inside the AlCl3 bottle 31.

[0037] (Step S14) Determine if the temperature of the AlCl3 bottle 31 is within the set temperature range. If it is within the set temperature range (YES), proceed to step S15. If it is outside the set temperature range (NO), return to step S12 and repeat steps S12 to S14 until the AlCl3 bottle 31 reaches the set temperature.

[0038] (Step S15) The absorbance meter 40 measures the absorbance of the AlCl3 gas (Al raw material gas) flowing through the AlCl3 supply pipe 21 based on a control signal CS from the growth control unit 50 that instructs absorbance measurement. The growth control unit 50 receives a measurement signal MS from the absorbance meter 40, which indicates the measured absorbance ABS of the Al raw material gas.

[0039] (Step S16) The growth control unit 50 determines whether the absorbance measurement value ABS has stabilized at the absorbance set value (e.g., 0.2) after N2 gas (air supply gas) is started to be supplied to the AlCl3 bottle 31. Specifically, as a stabilization condition, for example, absorbance is measured at a predetermined set measurement interval (e.g., every 5 seconds), and after the start of air supply, it is determined whether the fluctuation of the absorbance measurement value ABS remains within a predetermined set stabilization range (e.g., within ±10%) relative to the absorbance set value for a predetermined absorbance set stabilization time (e.g., 10 minutes). In other words, it is determined that the absorption is not stable when the fluctuation of the absorbance measurement value falls outside the set stabilization range relative to the absorbance set value.

[0040] The above-mentioned measurement interval is preferably 1 to 10 seconds, and the above-mentioned stabilization time is preferably 5 to 15 minutes. Furthermore, the above-mentioned variation range is preferably within ±10%, and more preferably within ±5%.

[0041] If it is determined that the absorbance of AlCl3 gas (Al raw material gas) is unstable (NO), proceed to step S17. If it is determined that the absorbance is stable (YES), proceed to step S18.

[0042] (Step S17) If it is determined in step S16 that the absorbance is not stable, the flow rate of the air supply gas (N2) to the AlCl3 bottle 31 is adjusted. The flow rate of the air supply gas can be adjusted, for example, based on the following equation (1).

[0043] Adjusted N2 flow rate = Unadjusted N2 flow rate × (Absorbance set value / Absorbance measured value) ... Equation (1) If the absorbance measurement is less than the absorbance set value, the flow rate of the gas (N2) supplied to the AlCl3 bottle 31 is increased based on equation (1) above. If the absorbance measurement is greater than the absorbance set value, the flow rate of the gas (N2) supplied to the AlCl3 bottle 31 is decreased based on equation (1) above. As a result, the ratio of the flow rate of the gas (N2) supplied to 31 to the N2 gas used for dilution increases when the absorbance measurement is less than the absorbance set value, and decreases when the absorbance measurement is greater than the absorbance set value. In addition, the flow rate control of the N2 gas for dilution using MFC33 may be used in combination. Even when the flow rate control of the N2 gas for dilution using MFC33 is used in combination, the ratio of the flow rate of the gas (N2) supplied to the AlCl3 bottle 31 to the N2 gas for dilution should be adjusted so that it increases when the absorbance measurement is less than the absorbance set value, and decreases when the absorbance measurement is greater than the absorbance set value.

[0044] After adjusting the flow rate of the supplied gas, return to step S15 and repeat steps S15 to S16. That is, adjust the flow rate of the supplied gas to the AlCl3 bottle 31 while measuring the absorbance of the AlCl3 gas.

[0045] (Step S18) If it is determined in step S16 that the absorbance has stabilized, the process proceeds to the crystal growth execution sequence.

[0046] (Step S21) Following step S18, the crystal growth furnace valve is turned ON, and Al raw material gas (AlCl3 gas) and NH3 gas (Group V raw material gas) are introduced into the reaction tube 12. This initiates the crystal growth of AlN.

[0047] (Step S22) The absorbance meter 40 measures the absorbance of the AlCl3 gas (Al raw material gas) flowing through the AlCl3 supply pipe 21 based on a control signal CS from the growth control unit 50 that instructs absorbance measurement. The growth control unit 50 acquires a measurement signal MS from the absorbance meter 40, which represents the absorbance measurement value ABS of AlCl3 gas.

[0048] (Step S23) The growth control unit 50 uses the same stability conditions as in step S16 to determine whether the absorbance measurement value ABS is stable within the set stability range (for example, within ±10%) relative to the set value. If it is determined that the absorbance of AlCl3 gas is not stable, i.e., that the fluctuation of the measurement value has fallen outside the set stability range (NO), the process proceeds to step S24. If it is determined that the absorbance is stable (YES), the process proceeds to step S25.

[0049] (Step S24) If it is determined in step S23 that the absorbance is not stable, the flow rate of the gas (N2) supplied to the AlCl3 bottle 31 is adjusted. The flow rate of the supplied gas can be adjusted based on the above equation (1). After adjusting the flow rate of the supplied gas, the process returns to step S22 and the steps from step S22 onward are executed. That is, the flow rate of the gas supplied to the AlCl3 bottle 31 is adjusted while measuring the absorbance of the AlCl3 gas.

[0050] (Step S25) In step S23, if it is determined that the absorbance is stable, it is determined whether or not the layer thickness of the grown crystal has reached the set layer thickness.

[0051] If it is determined that the set layer thickness has not been reached, the process returns to step S22, and the steps from step S22 onward are executed. That is, crystal growth continues while adjusting the flow rate of the air gas (N2) supplied to the AlCl3 bottle 31, and maintaining a stable absorbance of the AlCl3 gas.

[0052] If it is determined in this step that the set layer thickness has been reached, the process proceeds to step S26.

[0053] (Step S26) The crystal growth furnace valve is turned OFF, and the Al raw material gas (AlCl3 gas) and NH3 gas (Group V raw material gas) are exhausted from the exhaust section 13. In other words, the crystal growth of AlN is completed.

[0054] Therefore, changes in the concentration of AlCl3 gas supplied to the crystal growth furnace are suppressed, and crystal growth is carried out with a stable ratio of Al source gas to nitrogen source gas, making it possible to stably grow high-quality AlN single crystals with high crystallinity.

[0055] (3) Adjustment of the flow rate of the supplied gas (N2) Figure 3 shows the absorbance (cm²) of the mixed gas (Al raw material gas) of AlCl3 gas from AlCl3 bottle 31 and dilution N2 gas as a function of the flow rate (cc / min) of supplied N2 gas. -1 This indicates that...

[0056] This graph shows that the absorbance of supplied N2 gas is proportional to the flow rate. Therefore, as shown in equation (1), the absorbance of AlCl3 gas can be adjusted by multiplying the pre-adjustment N2 flow rate by (absorbance set value / absorbance measurement value) to obtain the adjusted N2 flow rate.

[0057] (4) Crystallinity of grown AlN crystals Figure 4 shows the absorbance (cm²) of the Al raw material gas (AlCl3 gas supplied to the reaction tube 12) as a function of the N2 gas supply time to the AlCl3 bottle 31. -1Figure 5 shows the full width at half maximum (FWHM) of the XRC (X-ray rocking curve) of the grown crystal when crystal growth is started at timings A and B shown in Figure 4, for cases where the growth plane is the (10-11) plane and for cases where the growth plane is the (0002) plane.

[0058] As shown in Figure 4, the absorbance of the AlCl3 gas supplied to the reaction tube 12 stabilizes as the supply time increases.

[0059] As shown in Figure 5, in Figure 4, if growth begins at time A, i.e., approximately 1 minute after the start of N2 gas supply, the XRC half-width is 210-270 cm. -1 And it's large. An XRC full width at half maximum of about 70 arcsecs is required for AlN growth substrates, but it can be seen that crystallinity is poor if growth is started before the absorbance of AlCl3 gas stabilizes.

[0060] On the other hand, in Figure 4, when growth is started at time B, that is, approximately 60 minutes after the start of N2 gas supply, the XRC half-width is 50 arcsec or less, indicating that a well-crystallinity AlN grown layer can be obtained.

[0061] Figure 6 shows microscopic images of the surface of the AlN growth layer when crystal growth is started before (at point A in Figure 4) and after (at point B in Figure 4) stabilization of the absorbance of the AlCl3 gas supplied to the reaction tube 12.

[0062] When crystal growth is initiated before the absorbance of AlCl3 gas stabilizes (at point A), numerous polycrystalline particles are observed on the surface. This is thought to be because an excess of AlCl3 is supplied in the early stages of growth, and the Al atoms are not incorporated into the crystal surface steps but instead become nuclei. As a result, tiny polycrystalline particles are generated on the surface.

[0063] On the other hand, if crystal growth is started after the absorbance of AlCl3 gas has stabilized (at point B), it can be seen that the excessive supply of AlCl3 is eliminated, and the formation of polycrystalline material can be suppressed.

[0064] (5) Stabilization of absorbance The phenomenon where the absorbance of AlCl3 gas increases at the start of supplying N2 gas to the AlCl3 bottle 31 and the phenomenon where the absorbance changes during use of AlCl3 gas are due to different causes.

[0065] In other words, at the start of supplying N2 gas, the bottle is saturated with AlCl3 gas. However, when the supplying N2 gas enters the AlCl3 bottle 31 and the sublimation rate of solid AlCl3 and the flow rate of the supplying N2 gas become equilibrium, the absorbance of the AlCl3 gas stabilizes.

[0066] Furthermore, during growth, the sublimation of solid AlCl3 reduces the size and surface area of ​​the granules (small pieces). As a result, the sublimation rate of solid AlCl3 slows down, and the amount of AlCl3 gas extracted from the AlCl3 bottle 31 decreases with each crystal growth, even when the same flow rate of N2 gas is supplied.

[0067] As shown in Figure 7, the rate of decrease in absorbance changes depending on the size of the solid AlCl3 particles, as indicated by P or Q (dashed line). Therefore, it is necessary to adjust the absorbance using the absorbance meter 40 during and after growth.

[0068] As described above, in the hydride vapor phase growth apparatus 10 of this disclosure, during the growth standby period, the flow rate of N2 gas supplied to the AlCl3 bottle 31 is adjusted, and crystal growth is performed when the absorbance is within a predetermined range for a set stabilization time.

[0069] Furthermore, during crystal growth, the flow rate of N2 gas supplied to the AlCl3 bottle 31 is adjusted, and crystal growth is carried out so that the absorbance is within a predetermined range.

[0070] As described in detail above, this disclosure provides an AlN crystal growth apparatus and an AlN crystal growth method that can stably grow high-quality AlN single crystals having high crystallinity. [Explanation of symbols]

[0071] 10:AlN crystal growth equipment 11: Reactor 12: Reaction tube 13: Exhaust section 14: Heater 15: Susceptor 16: Growth substrate 21:AlCl3 supply pipe 22: Supply pipe 22V, 23V, 24V: Switchable valve 23: Nitrogen raw material supply pipe 30: Gas Supply Department 31: AlCl3 bottle 32,33: MFC 37: Diverter valve 38: Piping 40: Absorbance measuring device 41: FT-IR gas cell 42:FT-IR light source 43: FT-IR Receiver 50: Growth Control Unit

Claims

1. A reaction tube and AlCl ３ The bottle and The aforementioned AlCl ３ A flow controller capable of adjusting the flow rate of air gas supplied to the bottle, The aforementioned AlCl ３ AlCl from the bottle ３ AlCl supplied gas to the reaction tube ３ supply pipe and A nitrogen raw material supply pipe for supplying nitrogen raw material gas to the reaction tube, The aforementioned AlCl ３ The AlCl is provided in the supply tube and supplied to the reaction tube. ３ An absorbance meter for measuring the absorbance of a gas, Based on the absorbance measurement value obtained by the absorbance meter, the flow rate controller is controlled to adjust the flow rate of the supplied gas and the AlCl ３ A control unit that controls the supply of gas to the reaction tube, An AlN crystal growth apparatus having the following features.

2. During crystal growth, the control unit measures the absorbance of the AlCl ３ The AlN crystal growth apparatus according to claim 1, which adjusts the flow rate of the gas being supplied while measuring the absorbance of the gas.

3. The AlN crystal growth apparatus according to claim 2, wherein the control unit adjusts the flow rate of the supplied gas when the fluctuation of the absorbance measurement value falls outside the set stable range with respect to the absorbance set value.

4. The AlN crystal growth apparatus according to claim 1, wherein the absorbance meter is a Fourier transform infrared spectrometer (FT-IR).

5. The supplied gas is nitrogen (N ２ ) is a gas, The control unit is defined by the following formula (1) After adjustment N ２ Flow rate = N before adjustment ２ Flow rate × (Absorbance setting value / Absorbance measurement value) ... Equation (1) Based on this, the flow rate of the supplied gas is adjusted. The AlN crystal growth apparatus according to claim 1.

6. The aforementioned AlCl ３ The AlCl of the supply pipe ３ It further includes a dilution gas supply pipe provided between the bottle and the absorbance meter for supplying the dilution gas, The supplied gas and the diluent gas are nitrogen (N ２ ) is a gas, The control unit, The AlN crystal growth apparatus according to claim 1, wherein the ratio of the flow rate of the supplied gas to the dilution gas is increased when the measured absorbance is less than the absorbance setting value, and decreased when the measured absorbance is greater than the absorbance setting value.

7. The control unit, when waiting for crystal growth, The aforementioned AlCl ３ The flow rate of the supplied gas is adjusted while measuring the absorbance of the gas. It is determined whether the fluctuation of the absorbance measurement value over the set stabilization time is within the set stabilization range. If it is determined that the fluctuations remain within the set stability range over the set stability time, control is performed to proceed to the execution of crystal growth. The AlN crystal growth apparatus according to claim 1.

8. A reaction tube and AlCl ３ The bottle and The aforementioned AlCl ３ A flow controller capable of adjusting the flow rate of air gas supplied to the bottle, The aforementioned AlCl ３ AlCl from the bottle ３ AlCl supplied gas to the reaction tube ３ supply pipe and An AlN crystal growth apparatus comprising a nitrogen raw material supply pipe for supplying nitrogen raw material gas to the reaction tube, wherein the AlN crystal growth apparatus is an AlN crystal growth method, The AlCl supplied to the reaction tube ３ While measuring the absorbance of the gas, the flow rate of the supplied gas is adjusted based on the measured absorbance to the AlCl ３ The gas is supplied to the reaction tube, An AlN crystal growth method for growing AlN single crystals.

9. The AlN crystal growth method according to claim 8, wherein the flow rate of the supplied gas is adjusted when the fluctuation of the measured value of the absorbance falls outside the set stable range with respect to the absorbance set value.

10. The AlN crystal growth method according to claim 8, wherein the absorbance measurement is performed using Fourier transform infrared spectroscopy (FT-IR).

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