JP2016216342A - Manufacturing method of group iii nitride single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a group III nitride single crystal of high quality that develops a crystal on a substrate by reacting a group III raw material gas and a nitrogen source gas and can reduce crystal defects causing bright points.SOLUTION: A manufacturing method of a group III nitride single crystal that develops a group III nitride single crystal on a base substrate by reacting a group III raw material gas and a nitrogen source gas is characterized by initiating the reaction of the group III raw material gas and the nitrogen source gas in the presence of a halogen-based gas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a novel method for producing a group III nitride single crystal. Specifically, in the method for producing a group III nitride single crystal by a vapor phase growth method using a group III source gas, a hydrogen halide gas and / or a halogen gas is supplied before supplying the group III source gas. The present invention relates to a novel manufacturing method characterized by the following.

  Group III nitride semiconductor crystals such as aluminum nitride, gallium nitride, and indium nitride have a wide range of band gap energy values, which are about 6.2 eV, about 3.4 eV, and about 0.7 eV, respectively. Degree. These group III nitride semiconductors can form mixed crystal semiconductors having an arbitrary composition, and can take values between the above band gaps depending on the mixed crystal composition.

  Therefore, by using a group III nitride semiconductor crystal, it is possible in principle to produce a wide range of light emitting elements from infrared light to ultraviolet light. In particular, in recent years, development of light-emitting elements using aluminum-based group III nitride semiconductors (mainly aluminum gallium nitride mixed crystals) has been vigorously advanced. By using an aluminum-based group III nitride semiconductor, it is possible to emit light with a short wavelength in the ultraviolet region, an ultraviolet light emitting diode for a white light source, an ultraviolet light emitting diode for sterilization, a laser that can be used for reading and writing of a high-density optical disk memory, and a communication laser A light emitting light source such as can be manufactured.

  A light-emitting element using a group III nitride semiconductor (for example, an aluminum-based group III nitride semiconductor) is a semiconductor single crystal thin film (specifically, a thickness of about several microns on a substrate, like a conventional semiconductor light-emitting element). The thin film can be formed by sequentially stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. Such a semiconductor single crystal thin film can be formed by using a crystal growth method such as a molecular beam epitaxy (MBE) method or a metalorganic chemical vapor deposition (MOCVD) method. Thus, it has been attempted to form a laminated structure suitable as a light emitting device by adopting such a method for the group III nitride semiconductor light emitting device.

  Currently, in the manufacture of group III nitride semiconductor light-emitting devices, a sapphire substrate is generally employed from the viewpoint of crystal quality, ultraviolet light transparency, mass productivity, and cost as a substrate. However, when a group III nitride is grown on a sapphire substrate, there is a difference in lattice constant, thermal expansion coefficient, etc. between the sapphire substrate and the group III nitride (such as aluminum gallium nitride) forming the semiconductor laminated film. As a result, crystal defects (misfit dislocations), cracks, and the like occur, causing the light emitting performance of the device to deteriorate.

  In order to solve these problems, it is desirable to use a substrate having a lattice constant close to that of the semiconductor multilayer film and a thermal expansion coefficient close to that of the semiconductor multilayer film when forming the semiconductor multilayer film. . Therefore, it can be said that a group III nitride single crystal substrate is most suitable as a substrate for forming a group III nitride semiconductor thin film. For example, an aluminum nitride single crystal substrate or an aluminum gallium nitride single crystal substrate is optimal as a substrate on which an aluminum-based group III nitride semiconductor thin film is formed.

  In order to use a group III nitride single crystal as a substrate, it is preferable that the single crystal has a certain thickness (for example, 10 μm or more) from the viewpoint of mechanical strength. Since the MOCVD method has a higher crystal growth rate than the MBE method, it can be said that the MOCVD method is suitable for manufacturing a group III nitride single crystal substrate. Further, a hydride vapor phase epitaxy (HVPE) method is known as a method for growing a group III nitride single crystal having a higher film forming rate than the MOCVD method (see Patent Documents 1 and 2). The HVPE method is not suitable for precisely controlling the film thickness as compared with the MBE method or the MOCVD method, but a single crystal having good crystallinity can be grown at a high film formation rate. It can be said that it is particularly suitable for mass production of single crystal substrates.

  Usually, group III nitride single crystal growth by MOCVD method or HVPE method is performed by supplying a group III source gas and a nitrogen source gas into a reactor and reacting both gases on a heated substrate. Done.

  In the HVPE method, various studies have been conducted in order to obtain a single crystal with good crystallinity. In particular, in the method for producing an aluminum-based group III nitride single crystal, an aluminum trihalide gas is used as a raw material gas. At this time, the raw material gas may contain aluminum monohalide which causes a decrease in crystal quality. In the HVPE method, a method of reducing the aluminum monohalide gas has been studied. For example, a production method is described in which generation of aluminum monohalide is suppressed by setting the reaction temperature between aluminum and hydrogen chloride gas within a specific temperature range (see Patent Documents 3 and 4). In addition, a method of depositing and removing aluminum monohalide gas contained in aluminum trihalide gas as metallic aluminum is also known (see Patent Document 5). According to these methods, since the aluminum monohalide gas can be efficiently reduced, the crystal quality of the aluminum-based group III nitride single crystal can be improved.

  However, higher quality single crystals have been desired in recent years, and further studies have been made. For example, by reacting an aluminum halide gas that is a source gas and a nitrogen source gas in the presence of a halogen-based gas such as hydrogen chloride gas, the equilibrium partial pressure of the aluminum monohalide gas is significantly reduced to produce a single crystal. A manufacturing method is known (see Patent Document 6). In addition, by adjusting the gas flow in the reactor, particles generated in the gas phase reaction (attached particles: particles observed with a Nomarski differential interference microscope (observed at 100 to 500 times)) adhere to the crystal growth surface. There is known a method for manufacturing a high-quality single crystal that prevents this (see Patent Document 7). By combining the methods described in Patent Documents 6 and 7 as described above and the conventional method, a higher quality single crystal can be produced.

JP 2006-114845 A JP 2006-073578 A JP 2003-303774 A JP 2012-166963 A International Publication WO2012 / 081670 Pamphlet JP 2015/017030 A International Publication WO2014 / 031119 Pamphlet

However, even when the present inventors adopt the above method (a method combining the method described in Patent Documents 6 and 7 and the conventional method of reducing the aluminum monohalide gas), for example, Even when the rectifying barrier described in Patent Document 7 was used, it was found that fine crystal defects exist in the aluminum nitride single crystal. That is, when the rectifying barrier is used, the number of adhered particles observed with a Nomarski differential interference microscope (observed at 100 to 500 times) can be reduced, but when evaluated by a reflection X-ray topograph, It was found that possible bright spots were observed. The crystal defects observed at this bright point may be observed even when the conventional method of reducing the aluminum halide gas is used or when the conventional technology is used in combination.
When a group III nitride single crystal is produced by a vapor phase growth method such as MOCVD method or HVPE method, a batch method (group III nitride is usually formed on a single crystal growth substrate (base substrate) in a reactor). After the single crystal is manufactured, the single crystal is taken out, and then another base substrate is placed in the reactor, and a group III nitride single crystal is manufactured again on the base substrate. According to the study by the present inventors, when a single crystal is repeatedly produced in such a batch method, in the prior art, a single crystal with many crystal defects observed as a bright spot may be frequently produced. In particular, there is room for improvement in the case of repeated production in a batch system.

  Accordingly, an object of the present invention is to provide a method for producing a group III nitride single crystal capable of reliably reducing crystal defects observed as bright points by a reflection X-ray topograph, and in particular, it is repeatedly produced in a batch system. It is an object of the present invention to provide a method for producing a group III nitride single crystal in which the crystal defects can be reduced in each single crystal.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. First, this bright point will be described in detail, which corresponds to a crystal defect observed when a diffraction image from, for example, the (114) plane of an aluminum nitride single crystal (AlN single crystal) substrate is observed by a reflection X-ray topograph. Yes, when the (114) plane is observed, it is observed as a bright point as a result of increased diffraction at the defect portion. When the diffracting surface to be measured is changed, the defective portion may be projected as a dark spot. The bright point is considered to be a crystal defect and causes a decrease in yield of the LED or electronic device (current leakage path).

  Next, the mechanism by which this crystal defect occurs is considered for this bright point. Reference is made to Patent Document 6 in which a single crystal having good crystallinity can be obtained. Crystal growth is performed in the presence of hydrogen chloride gas, and at which stage during single crystal growth, a crystal defect observed as a bright spot is generated. confirmed. As a result, it was found that the influence of a bright spot generated immediately after the start of growth was the largest, although not limited to immediately after the start of growth.

  Therefore, the present inventors have studied a method that can reliably reduce aluminum monohalide from the initial stage of single crystal growth, and as a result, before supplying the group III source gas onto the base substrate, hydrogen halide gas, By adopting a method of supplying at least one halogen-based gas selected from halogen gas, crystal defects that cause bright spots are reduced, and variation in the number of bright spots is reduced even during repeated manufacturing. As a result, the present invention has been completed.

  That is, the present invention provides a group III nitride single crystal on a base substrate by supplying a group III source gas and a nitrogen source gas to the base substrate for reaction in a reactor equipped with the base substrate. And supplying at least one halogen-based gas selected from a hydrogen halide gas and a halogen gas onto the base substrate before supplying the group III source gas. This is a method for producing a group III nitride single crystal.

  In the present invention, it is preferable to supply the nitrogen source gas onto the base substrate, then supply the halogen-based gas onto the base substrate, and then supply the group III source gas onto the base substrate. By supplying the nitrogen source gas first, decomposition of the crystal growth surface of the base substrate can be prevented, and a high-quality group III nitride single crystal can be manufactured.

In the present invention, when the halogen-based gas is continuously supplied and the group III source gas is supplied, the supply amount of the halogen-based gas in a standard state is set to V _H (sccm), When the supply amount of the gas in the standard state is V _III (sccm), it is preferable to supply the halogen-based gas and the group III source gas so as to satisfy the following formula (1).
0.5 ≦ V _H / (V _H + V _III ) <1.0 (1)
The halogen-based gas is continuously supplied onto the base substrate before supplying the group III source gas. When the group III source gas is supplied, the supply amount of the halogen-based gas satisfies the formula (1). By doing so, the crystal defects of the finally obtained group III nitride single crystal (for example, in the case of an aluminum nitride single crystal, the number of bright spots present in the reflected X-ray topographic image of the (114) plane) are further increased. Can be reduced. In the present invention, the “standard state” in a gas such as a halogen-based gas, a group III source gas, and a nitrogen source gas means a state at a temperature of 0 ° C. and a pressure of 1 atm.

  The present invention is based on the HVPE method in which the group III source gas is a gas containing aluminum trichloride gas and the nitrogen source gas is ammonia gas, that is, the control is difficult, the growth rate is high, and the reactive material is used. It is suitable for producing an aluminum-based group III nitride single crystal, particularly an aluminum nitride single crystal.

  Furthermore, the present invention is a group III of stable quality with little variation in the number of bright spots (number of fine crystal defects) when a group III nitride single crystal is produced repeatedly using the same reactor. A nitride single crystal can be repeatedly produced.

  According to the method of the present invention, crystal defects observed as a bright spot immediately after the start of growth can be reliably reduced by simple means. And when manufacturing a group III nitride single crystal repeatedly, the bright point of these single crystals can be reduced, and a group III nitride single crystal with constant quality can be manufactured. As a result, it is possible to repeatedly provide a high-quality group III nitride single crystal excellent in ultraviolet region transparency.

  Furthermore, when a wafer having a light emitting element layer formed on the obtained group III nitride single crystal is manufactured and then the wafer is cut to obtain a light emitting diode, the yield of the light emitting diode can be improved.

It is a figure which illustrates typically an example of the vapor phase growth apparatus which can be used for implementation of this invention. It is an image in which a bright point is observed by reflection X-ray topography measurement. It is an image in which a bright point was not observed in reflection X-ray topography measurement.

  In the present specification, “A to B” for the numerical values A and B means “A or more and B or less” unless otherwise specified. In the notation, when the unit of the numerical value A is omitted, the unit attached to the numerical value B is applied as the unit of the numerical value A. In addition, the form shown below is an illustration of this invention and this invention is not limited to these forms.

  The present invention is a method for producing a group III nitride single crystal on a base substrate by supplying a group III source gas and a nitrogen source gas onto the base substrate in a reactor equipped with the base substrate. . Then, before supplying the group III source gas, at least one halogen-based gas selected from a hydrogen halide gas and a halogen gas is supplied onto the base substrate.

  In the present invention, a known method can be employed except that the halogen-based gas is supplied before crystal growth. In the following, description will be given in order.

<Carrier gas>
In the present invention, in order to supply the group III source gas and the source gas of the nitrogen source gas onto the base substrate in the reactor, a carrier gas is supplied into the reactor to form a flow of the source gas. preferable. As the carrier gas, hydrogen gas and / or various inert gases can be used. As the carrier gas, one kind of gas can be used, or two or more kinds of gases can be mixed and used. Among these, it is preferable to use one or more kinds selected from hydrogen gas and nitrogen gas as the carrier gas in that the production of the group III nitride single crystal is not adversely affected. The carrier gas supply amount can be appropriately determined according to the volume of the reactor, but is generally preferably 50 to 50000 sccm, and more preferably 100 to 10000 sccm, for example. sccm is a unit of mass flow rate that means a value obtained by converting a flow rate per minute into a volume (cc) in a standard state (0 ° C., 1 atm). Further, it is preferable to remove impure gas components such as oxygen, water vapor, carbon monoxide and carbon dioxide in advance using a purifier.

<Group III source gas>
In the present invention, the group III source gas is not particularly limited, and a known source gas used when producing a group III nitride single crystal by MOCVD method or HVPE method may be used. Among them, the effect of the present invention is remarkable when a group III source gas containing aluminum is used. For example, in the case of the HVPE method, an aluminum halide gas such as an aluminum chloride gas or an aluminum iodide gas is used. In the case of the MOCVD method, an organic metal gas such as trimethylaluminum gas or triethylaluminum gas is used.

  Among these, an aluminum halide gas (mainly a gas containing an aluminum trihalide gas, most preferably a gas containing an aluminum trichloride gas) is highly reactive and obtains a high growth rate. Therefore, the present invention is suitable for the raw material gas used in the present invention (that is, the present invention is suitable for the HVPE method using an aluminum halide gas that is highly reactive, can obtain a high growth rate, and is difficult to control. Is suitable.). The aluminum halide gas may be supplied by vaporizing solid aluminum halide. By reacting metal aluminum with a halogen-based gas for raw material generation such as hydrogen chloride gas or chlorine gas, an aluminum halide gas is obtained. Also good. When producing an aluminum halide gas from metallic aluminum, it is preferable to use a solid having a purity of 99.99% or more as the aluminum used as a raw material for the aluminum halide gas. Of course, the most preferred aluminum purity is 100%. Although liquid aluminum can be used depending on the contact temperature between aluminum and the raw material generating halogen-based gas, it is preferable to use solid aluminum in consideration of the contact efficiency with the raw material generating halogen-based gas. . When solid aluminum is used, its size and shape are not particularly limited. However, in an actual apparatus used, contact efficiency between aluminum and halogen gas for raw material generation, and easy distribution of halogen gas. In consideration of the above, for example, a pellet having a diameter of 0.1 to 10 mm and a length of 0.1 to 10 mm can be suitably used.

  Alternatively, an aluminum halide gas may be obtained by utilizing a reaction between an organometallic gas containing aluminum and a halogen gas for raw material generation.

  The group III source gas as described above is preferably supplied onto the base substrate together with the carrier gas. When the group III source gas is supplied in a state diluted with a carrier gas, the concentration of the group III source gas may be, for example, 0.0001 to 10% by volume. The supply amount of the group III source gas can be, for example, 0.005 to 500 sccm. The group III source gas must be supplied onto the base substrate after supplying the following halogen gas.

<Nitrogen source gas>
In the present invention, a nitrogen source gas is supplied onto the base substrate in order to obtain a group III nitride single crystal. As the nitrogen source gas, a reactive gas containing nitrogen is adopted, but it is preferable to use ammonia gas in terms of cost and ease of handling.

  This nitrogen source gas is usually diluted appropriately in the carrier gas and supplied onto the base substrate. When the carrier gas is supplied onto the base substrate, the supply amount of the nitrogen source gas and the supply amount of the carrier gas may be determined depending on the size of the apparatus. Considering the ease of production of the group III nitride single crystal, etc., the supply amount of the carrier gas is preferably in the range of 50 to 10,000 sccm, and more preferably in the range of 100 to 5000 sccm. A practical concentration of the nitrogen source gas may be selected from a range of 0.0000001 volume% to 10 volume% with respect to the carrier gas. Further, the supply amount of the nitrogen source gas can be in the range of 0.01 to 1000 sccm. The order of supplying the nitrogen source gas onto the base substrate is not particularly limited, but it is preferable to supply the nitrogen source gas onto the base substrate before the halogen-based gas and the group III source gas are supplied.

<Halogen gas>
In the present invention, at least one halogen-based gas selected from a hydrogen halide gas and a halogen gas is supplied onto the base substrate before the group III source gas is supplied. That is, before the group III source gas and the nitrogen source gas are supplied onto the base substrate and both react, the halogen-based gas is always supplied onto the base substrate.

  Examples of the halogen gas include chlorine gas and bromine gas. Examples of the hydrogen halide gas include hydrogen chloride gas and hydrogen bromide gas. Among these, it is preferable to use hydrogen chloride gas in consideration of low corrosiveness to gas piping, ease of handling, and economy.

<Supply amount of halogen-based gas before supplying Group III source gas>
In the present invention, the halogen-based gas is supplied onto the base substrate before the group III source gas is supplied onto the base substrate. The time until the halogen-based gas is supplied onto the base substrate is the discharge port portion of the nozzle to which the halogen-based gas is supplied (in the apparatus 100 of FIG. 1, the nitrogen source gas outlet 33 or the group III source gas outlet). 25) to the base substrate (cm ³ ; volume in the reaction zone preceding supply gas calculation range 36 in the apparatus 100 of FIG. 1), the halogen-based gas supply flow rate (cm ³ / min: Alternatively, when the halogen-based gas is supplied simultaneously with another gas such as a carrier gas, it can be obtained by dividing by the total supply flow rate of the other gas and the halogen-based gas. In addition, the time from the start of the introduction of the halogen-based gas to the arrival of the halogen-based gas at the nozzle outlet is determined by the amount of halogen-based gas from the nozzle inlet to the outlet where the halogen-based gas is introduced. The total volume in the pipe constituting the movement path is determined based on the supply flow rate of the halogen-based gas (or other gas such as a halogen-based gas and another gas such as a carrier gas when they are simultaneously circulated through the same pipe. And the total supply flow rate of the gas and the halogen-based gas). In the present invention, after supplying the halogen-based gas into the reactor and then supplying the group III source gas after the time calculated by this method, the halogen-based gas is surely supplied before the group III source gas is supplied. Can be supplied onto the base substrate.

The supply amount of the halogen-based gas in the standard state (supply amount until the group III source gas is supplied (sccm); hereinafter referred to as V _H0 ) is not particularly limited, and depends on the size of the apparatus. Its absolute amount can be determined. However, from the viewpoint of producing a stable group III nitride single crystal by reducing the change in gas flow immediately after the start of growth, the halogen-based gas is not only used before the supply of the group III source gas is started. It is preferable to supply continuously after the supply of the group III source gas is started, and it is preferable not to change the supply amount (absolute amount) even after the supply of the group III source gas is started. That is, when the supply amount in terms of the standard state of the halogen-based gas after the supply of the group III source gas is started is V _H (sccm), it is preferable that V _H0 = V _H. V _H0 and V _H are the total amount of all halogen-based gases supplied. Reducing the change in gas flow makes it easy to reproduce the same gas atmosphere when repeatedly producing a plurality of group III nitride single crystals, so that the quality of the plurality of group III nitride single crystals produced can be improved. It becomes easy to reduce variation. Similarly, when the nitrogen source gas is supplied prior to the group III source gas, the supply amount (absolute amount) of the nitrogen source gas is preferably not changed before and after the start of the group III source gas.

<Supply amount of halogen-based gas after group III source gas supply>
The supply amount of the halogen-based gas when supplying the group III source gas is not particularly limited. However, from the viewpoint of improving the crystal quality of the finally obtained group III nitride single crystal, it is preferable to adjust so as to satisfy the following relational expression (1). Specifically, when the supply amount of the halogen-based gas in the standard state is V _H (sccm) and the supply amount of the group III source gas in the standard state is V _III (sccm), the fraction of the halogen-based gas (H _epi = V _H / (V _H + V _III ))
0.5 ≦ V _H / (V _H + V _III ) <1.0 (1)
Is preferably satisfied.

By supplying the halogen-based gas so that the fraction (H _epi ) of the halogen-based gas satisfies the formula (1), the equilibrium partial pressure of the monohalide gas of group III element (for example, aluminum monohalide gas) is obtained. Therefore, the number of bright spots in the reflected X-ray topographic image of the (114) plane is reduced in the case of a single crystal of higher quality (for example, in the case of an aluminum nitride single crystal). ) Can be manufactured. Considering industrial production such as the number of bright spots and the growth rate, the halogen gas fraction (H _epi ) is more preferably 0.55 or more and less than 1.0, and 0.6 or more and 1. More preferably, it is less than 0.

  In the present invention, the halogen-based gas is preferably continuously supplied onto the base substrate. The method for rejecting the halogen-based gas when supplying the group III source gas is not particularly limited. For example, a halogen gas supply line may be provided in the reactor and supplied from there.

  When the group III source gas is obtained by reaction of metal aluminum or organometallic gas with a raw material generating halogen-based gas, the reaction between the metal aluminum or organic metal gas and the raw material generating halogen-based gas is intentionally unreacted. By controlling the reaction rate so that the gas remains, it is possible to generate a mixed gas of the group III source gas and the halogen-based gas and supply the mixed gas to the reaction zone 10.

  Alternatively, a flow path for merging the halogen-based gas may be provided in the nitrogen source gas supply line to obtain a mixed gas of the nitrogen source gas and the halogen-based gas, and then supplied to the base substrate. In this case, since the halogenated nitrogen compound may be generated by the reaction of the nitrogen source gas and the halogen-based gas, the gas temperature is preferably heated to a temperature at which the halogenated nitrogen compound does not precipitate. For example, when ammonia gas is used as the nitrogen source gas and hydrogen chloride is used as the halogen-based gas, ammonium chloride may precipitate. Therefore, at least 300 ° C. or higher, more preferably higher than the decomposition temperature of ammonium chloride, more preferably 350 Heat to above ℃. The upper limit value of the heating temperature is not particularly limited, but is preferably 1200 ° C.

  Moreover, in order to make precipitation difficult to occur, the gas can be supplied while being diluted with a known carrier gas such as nitrogen gas, hydrogen gas, or rare gas.

<Base substrate>
In the present invention, the base substrate on which the group III nitride single crystal is grown is not particularly limited, and a known substrate can be used. Specifically, for example, sapphire, silicon carbide, gallium nitride, aluminum nitride, aluminum gallium nitride, zirconium boride, titanium boride and the like are used. Further, the thickness of the base substrate is not particularly limited, and can be 100 to 2000 μm. In addition, regarding the crystal plane orientation, + c plane, -c plane, m plane, a plane, r plane, etc. can be used without any particular limitation.

<Other manufacturing conditions>
By employing the above group III source gas, nitrogen source gas, halogen-based gas, base substrate, and supply conditions thereof, a group III nitride single crystal with few bright spots can be produced. Next, manufacturing conditions other than those described above will be described.

  Before the group III nitride single crystal is grown on the base substrate, it is preferable to perform thermal cleaning by a known method. For example, it is preferable to perform thermal cleaning in which the base substrate is heated while flowing a carrier gas containing hydrogen over the base substrate to remove organic substances attached to the base substrate. Specifically, when the base substrate is an aluminum nitride substrate or a sapphire substrate, generally, a carrier gas containing hydrogen is supplied, and the base substrate is heated to 1000 ° C. or higher and below the growth temperature of the group III nitride single crystal. It is preferable to hold for about minutes.

  At least one selected from a hydrogen halide gas and a halogen gas by heating the base substrate to a growth temperature at which the group III nitride single crystal grows (a temperature at which the base substrate reacts with the group III source gas and the nitrogen source gas). The halogen-based gas is supplied onto the base substrate. After the halogen-based gas is supplied up to the base substrate, the group III source gas is supplied to react the group III source gas with the nitrogen source gas. Start crystal growth. The supply sequence of the source gas, specifically the nitrogen source gas, the group III source gas, and the halogen-based gas is (i) the nitrogen source gas, the halogen-based gas, and the group III source gas are supplied in this order. (Iii) A method of supplying a halogen-based gas, a group III source gas, and a nitrogen source gas in this order can be employed. In (i), the nitrogen source gas and the halogen-based gas can be supplied simultaneously. In (ii) and (iii), the nitrogen source gas and the group III source gas can be supplied simultaneously. . Among them, it is preferable to employ the method (i) in order to prevent decomposition of the crystal growth surface of the base substrate. That is, the step of starting the supply of the nitrogen source gas onto the substrate, the step of starting the supply of the halogen-based gas onto the substrate, and the step of starting the supply of the group III source gas onto the substrate are performed. It is preferable to include in order.

  And the temperature (growth temperature) of the base substrate at the time of crystal growth is not particularly limited, and known conditions can be adopted. Specifically, the growth temperature is preferably 1000 to 1700 ° C.

  In particular, when producing an aluminum-based group III nitride single crystal using an aluminum halide gas, particularly an aluminum nitride single crystal, the temperature (growth temperature) of the base substrate is preferably 1200 to 1600 ° C. Furthermore, when the group III source gas is an aluminum halide gas, the supply amount of the aluminum halide gas can be set to 0.001 to 100 sccm, for example. It is preferable to supply a sufficient amount of the aluminum halide gas so that the growth rate of the aluminum-based group III nitride single crystal is 10 μm / h or more, more preferably 15 μm / h or more. From the viewpoint of improving crystallinity, the upper limit of the crystal growth rate is preferably 100 μm / h or less. However, when means for heating the base substrate from the outside is provided, the upper limit is set to 100 μm / h or more. (The upper limit of the growth rate when an external heating means is provided is about 300 μm / h).

  In the process of growing a group III nitride single crystal, by doping an element having a valence different from that of a group III element and a group V element to which nitrogen belongs, the electrical conductivity of the crystal is changed to n-type or p-type, or Crystal growth orientation in the + c-axis direction, -c-axis direction, m-axis direction, a-axis direction, etc. by controlling to semi-insulating, or by causing doped impurities to act as surfactants in the growth of group III nitride single crystals It is also possible to control. As these dopants, molecules containing elements such as C, Si, Ge, Mg, O, and S can be used without particular limitation.

  Further, in the present invention, in order to produce a group III nitride single crystal, a group III source gas and a nitrogen source gas are supplied onto the base substrate, but a group III source gas is used for the purpose of controlling the mixing of both gases. A barrier gas may be supplied between the gas and the nitrogen source gas. The barrier gas is appropriately selected from known gases such as hydrogen gas, nitrogen gas, argon gas, and helium gas, and these can be used alone or in combination. Among these, nitrogen gas and argon gas are preferable for suppressing mixing. The supply amount of the barrier gas may be determined depending on the size of the apparatus, the effect of suppressing mixing, and the like, but may be, for example, 50 to 10000 sccm, and preferably, for example, 100 to 5000 sccm.

  Other conditions may be appropriately determined according to the outline of the apparatus, the raw materials used, etc., but the pressure inside the reactor is in the range of 0.2 to 1.5 atm during the growth of the group III nitride single crystal. It is preferable.

  In addition, after the group III nitride single crystal is grown on the base substrate for a predetermined thickness so as to have the intended film thickness, the supply of the group III source gas is stopped and the growth of the group III nitride single crystal is completed. The substrate is cooled to room temperature. A known condition may be adopted as the condition at this time.

  In the present invention, after the growth of the group III nitride single crystal is completed by the method as described above, the group III nitride single crystal is repeatedly grown (manufactured) by the same method using the same reactor again. ), A stable group III nitride single crystal with few bright points can be produced. That is, when a group III nitride single crystal is repeatedly produced using the same reactor in a batch system, the number of bright spots is increased by supplying a halogen-based gas onto the base substrate before supplying the group III source gas. Thus, a stable group III nitride single crystal having a small variation can be produced.

  An apparatus for producing a group III nitride single crystal by the HVPE method that can be suitably used in the present invention will be described.

<Group III nitride single crystal production equipment>
FIG. 1 shows a schematic diagram of an HVPE manufacturing apparatus that can be suitably used in the present invention. In FIG. 1, as a group III nitride single crystal manufacturing apparatus 100, a reactor 11 provided with a base substrate 12, a group III source gas supply nozzle 24 (group III source) for supplying a group III source gas onto the base substrate. A group III source gas is discharged from the gas outlet 25 onto the base substrate), a nitrogen source gas supply nozzle 32 for supplying the nitrogen source gas onto the base substrate (a nitrogen source gas is introduced from the nitrogen source gas inlet 31) The nitrogen source gas is discharged onto the base substrate from the nitrogen source gas outlet 33), the extruded gas inlet 14 for supplying a carrier gas for creating a gas flow in the system, and the gas supplied into the reactor 11 The apparatus provided with the exhaust port 15 for discharging | emitting is shown.

  In the reactor 11, the base substrate 12 is held by a support base (susceptor) 13, and the base substrate 12 can be heated by heating the support base (susceptor) 13. In the present invention, the base substrate 12 is the reaction zone 10 where the group III source gas and the nitrogen source gas mainly react.

  Further, for the purpose of illustrating the HVPE manufacturing apparatus, a raw material part reactor 21 in which a group III metal raw material 22 (for example, aluminum) is arranged (a raw material part for producing a group III raw material gas after the group III metal raw material 22) Reaction zone 20). In this raw material section reactor 21, a raw material halogen-based gas introduction nozzle 23 for introducing a halogen-based gas that reacts with the group III raw material metal 21 to generate a group III source gas, and the generated group III source gas is a base substrate. A group III source gas supply nozzle 24 is provided for supply above. In this raw material part reactor 21, it is preferable to arrange the raw material part external heating device 16 outside in order to set the inside to a desired temperature.

  In FIG. 1, a group III additional halogen-based gas supply nozzle 26 and a group V additional halogen-based gas supply nozzle 34 are shown to supply a halogen-based gas onto the base substrate 12. The group III additional halogen-based gas supply nozzle 26 joins with the group III source gas supply nozzle 24 at the group III additional halogen-based gas merging portion 27. Further, the group V additional halogen-based gas supply nozzle 34 merges with the nitrogen source gas supply nozzle 32 at the group V additional halogen-based gas supply unit 35. In the present invention, the halogen-based gas can be supplied onto the base substrate from the group III additional halogen-based gas supply nozzle 26 and the group V additional halogen-based gas supply nozzle 34. In the present invention, the method for supplying the halogen-based gas is not particularly limited, and the halogen-based gas may be supplied from either or both of the group III additional halogen-based gas supply nozzle 26 and the group V additional halogen-based gas supply nozzle 34. Although not shown in FIG. 1, the halogen-based gas may be directly supplied to the reaction zone 10 (mainly on the base substrate 12) from an independent supply nozzle. Preferably, a method in which the reaction is easily controlled and mixed with the raw material gas is supplied.

  In the present invention, it is necessary to set the temperature so that a single crystal growth reaction proceeds on the base substrate. However, the base substrate can be heated by a known method. Although FIG. 1 shows the growth part external heating device 17 by a hot wall heating method (resistance heating method, radiation heating method, etc.), a cold wall type heating method for locally heating the support base (susceptor) 13. (High frequency induction heating method, substrate heating method by light, etc.) can also be adopted.

  Examples of the material constituting the group III nitride single crystal device 100 include heat-resistant glass, quartz glass, alumina, zirconia, pyrolytic boron nitride, stainless steel, and corrosion-resistant alloys such as Inconel. It can be preferably used. However, since the reaction zone 10 is heated to a high temperature, the tips of the various nozzles are also heated to a high temperature. If the vaporized component from the quartz glass is anxious, high temperatures such as pyrolytic boron nitride and alumina are used. It is also possible to use heat-resistant ceramics.

  In this embodiment, since the reactor 11 has the reaction zone 10 inside, it is preferable to be comprised with heat resistant and acid resistant nonmetallic materials, such as quartz glass, an alumina, a sapphire, and heat resistant glass. An outer chamber (not shown) may be disposed on the outer periphery of the reactor 11. The outer chamber may be made of the same material as that of the reactor 11, but the outer chamber is not in direct contact with the reaction zone 10, so it can be made of a general metal material such as stainless steel. It is.

  In the above description related to the present invention, the group III nitride single crystal manufacturing apparatus 100 in which the group III nitride single crystal is grown by the HVPE method is mainly exemplified, but the present invention is not limited to this mode. Further, although a horizontal apparatus is shown in FIG. 1, there is no particular limitation, and a vertical structure may be used. It is also possible to use a vapor phase growth apparatus in which a group III nitride single crystal is grown by MOCVD. More specifically, a vapor phase growth apparatus in which a group III organometallic compound gas (such as trimethylaluminum gas) is supplied as a group III source gas can be used. In that case, the raw material part reactor 21 is not provided with the group III metal raw material 22 but is supplied with a gas obtained by vaporizing a group III organometallic compound as the group III source gas.

<Group III nitride single crystal: preferred single crystal (aluminum nitride single crystal)>
By the manufacturing method as described above, the progress of the reaction between the group III source gas and the nitrogen source gas immediately after the start of growth in the reaction zone 10 can be mitigated by the additional halogen-based gas, and crystal defects that cause bright spots can be reduced. it can. As a result, even if it is an aluminum nitride single crystal by the HVPE method in which it is difficult to grow a high-quality crystal, an aluminum nitride single crystal with reduced crystal defects can be produced repeatedly. Specifically, the average value of the bright spot density existing in the reflected X-ray topographic image of the (114) plane is 0 to 20 / cm ² , the standard deviation is 0 to 10 / cm ² , and the standard deviation / average value is An aluminum nitride single crystal of 0 to 100% can be produced. Further, in order to improve the yield of LEDs and electronic devices, it is preferable that the standard deviation is 0 to 5 / cm ² , the standard deviation is 0 to 2 / cm ² , and the standard deviation / average value is 0 to 60%. However, when the average value of the light spot density is extremely small (for example, 0.5 / cm ² or less), the average value and the standard deviation value may be close to each other. When the average value of the light spot density is extremely small, the standard deviation / average value may seem to be out of the range of 0 to 100%, so the standard deviation / average index is not considered.

Further, from the above manufacturing method, the average value of the bright point density 0-20 pieces / cm ² (preferably 0-5 / ^cm 2), the standard deviation of 0 to 10 / cm ² (preferably 0-2 / Cm ² ), standard deviation / average value of 0 to 100% (preferably 0 to 60%), producing a high-quality aluminum nitride single crystal having a crystal growth surface area of 100 mm ² or more. Can do. The upper limit of the area of the crystal growth surface is not particularly limited, and the larger the value, the more industrially advantageous. However, considering the industrial production, the upper limit of the area of the crystal growth surface in order to satisfy the requirements of the present invention is 10000 mm ² (in this case, the range of the area 100～10000Mm ² of the crystal growth surface, The average value of the light spots is 0 to 20 / cm ² (preferably 0 to 5 / cm ² ), the standard deviation is 0 to 10 / cm ² (preferably 0 to 2 / cm ² ), and the standard deviation / The average value may be 0 to 100% (preferably 0 to 60%).

  In the present invention, the group III nitride single crystal can be produced by an apparatus having a structure in which a group III source gas, a nitrogen source gas, and a halogen-based gas can independently operate the supply flow rate and the valve. By using this apparatus to determine the order of gas supply at the beginning of growth, a group III nitride single crystal with few bright spots and improved crystal quality can be produced. In Patent Document 6 of the prior art, the halogen-based gas and the group III source gas are supplied simultaneously. Therefore, there is no problem when the halogen-based gas and the group III source gas are actually supplied onto the base substrate at the same time. However, since this is a gas phase reaction, the halogen-based gas precedes or the group III source gas is present. It is thought that the case where it preceded was easy to occur. When the group III source gas is supplied to the reaction zone 10 (mainly on the base substrate 12) ahead of the halogen-based gas, an insufficient time for the halogen-based gas is generated at the beginning of the growth, It is considered that fine crystal defects (bright spots existing in the reflected X-ray topographic image) considered to be the cause increase. Furthermore, when iteratively manufactures, the flow of the source gas and halogen gas changes due to the condition of the equipment members and slight growth temperature, the time when the halogen gas is insufficient changes, and the standard deviation of the number of bright spots Is thought to increase. In particular, this phenomenon is considered to be remarkable in the production of a nitride single crystal containing aluminum using a source gas containing aluminum having high reactivity. In the present invention, focusing on the source gas atmosphere at the beginning of growth, starting the reaction between the group III source gas and the nitrogen source gas in the presence of the halogen-based gas on the base substrate, the group III source gas and the nitrogen source are started. It is presumed that the reaction with the gas is effectively inhibited kinetically, and the crystal defect suppression effect can be obtained remarkably and stably.

The group III nitride single crystal substrate produced by the group III nitride single crystal manufacturing apparatus removes the polishing damage layer on the surface by chemical mechanical polishing (CMP), and the reflection X-ray topographic image shows polishing damage and polishing scratches. Was not observed. The surface roughness was finished in a state of 0.15 μm or less as the root mean square roughness (RMS) by 5 × 5 μm ² field observation with an atomic force microscope. When there are polishing flaws, the bright point becomes unclear, making it difficult to evaluate the present invention. In the case of cutting the wafer, known methods such as laser dicing, blade dicing, and stealth dicing can be employed without any particular limitation.

<Evaluation method of group III nitride single crystal>
A bright spot was observed on the surface of the group III nitride single crystal substrate whose surface was flattened by reflection X-ray topography. In this embodiment, the observation is made from the (114) plane.

  In the present invention, a reflection type X-ray topograph is used instead of a transmission type. The reason is to observe defects on the outermost surface of the substrate. This is because, when a laminated structure that functions as a light emitting element or an electronic device is formed on the aluminum nitride single crystal substrate obtained by the present invention, defects on the outermost surface of the substrate affect the above functions. For example, in the case of forming a light emitting element on an aluminum nitride single crystal substrate, if a crystal defect exists on the surface of the substrate, problems such as current leakage will be caused.

  On the other hand, X-ray rocking curve measurement, which is a conventional evaluation method, is a technique for observing average characteristics in the substrate surface, and is difficult to detect by measurement in a narrow region such as a bright spot.

  For this reason, the obtained group III nitride single crystal is obtained by evaluating crystal defects at a bright point existing in a reflected X-ray topographic image.

<Applications of group III nitride single crystals>
Since the group III nitride single crystal obtained by the method of the present invention has few crystal defects, it can be suitably used as a growth substrate for light emitting diodes, a light emitting diode substrate, and a substrate for electronic devices. In particular, a group III nitride single crystal having a crystal growth surface of 100 mm ² or more and a number density of bright spots of 5 pieces / cm ² or less is a laminate obtained by forming a light emitting element layer thereon When the light emitting diode is formed by cutting the (wafer), the yield can be improved. If the standard deviation is 2 pieces / cm ² or less and the standard deviation / average value is 60% or less, the yield can be easily predicted in the repeated manufacturing, and inventory management becomes easy. Therefore, it is possible to prevent excess inventory and inventory shortage.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example. In Examples and Comparative Examples, an example in which an aluminum nitride single crystal is manufactured among Group III nitride single crystals is shown.

(Evaluation of crystal defects by reflection X-ray topograph)
A high-resolution thin film X-ray diffractometer (X'Pert Pro MRD manufactured by Panalical) was used for measurement of the reflected X-ray topograph. Characteristic X-rays were generated on an X-ray tube using a Cu target under the conditions of an acceleration voltage of 45 kV and a filament current of 40 mA, and the X-ray beam was extracted with a line focus. The generated X-ray beam was converted into a high-intensity parallel X-ray beam by an X-ray mirror module (Gobel mirror). At this time, after installing a 1/2 ° divergence slit (horizontal limiting slit) and a 50 μm wide vertical limiting slit at the entrance of the X-ray mirror module to obtain an X-ray beam with a beam width reduced to about 1.2 mm, The aluminum nitride single crystal substrate, which is an object placed on the measurement stage, was irradiated. A CuKα1 line diffracted from the (114) plane of the aluminum nitride single crystal substrate was detected by a two-dimensional semiconductor X-ray detector (Panacelical PIXcel3D semiconductor detector) to obtain a reflected X-ray topographic image. Since it is 256 × 256 pixels of the two-dimensional semiconductor X-ray detector, the substrate area that can be measured by one reflection X-ray topographic image is limited to about 8.4 mm in the y direction and about 5.7 mm in the x direction. For this reason, in order to measure the reflected X-ray topographic image of the entire surface of the substrate, the measurement stage is appropriately moved in the x and y directions, and the reflected X-ray topographic image at another location in the substrate surface is measured repeatedly. The reflected X-ray topographic images of the entire surface of the substrate were acquired by connecting the reflected X-ray topographic images at the respective positions within the substrate surface. The obtained reflected X-ray topographic image was subjected to image analysis to count the number of bright spots and divided by the area of the aluminum nitride single crystal substrate to calculate the density of bright spots per 1 cm ² (pieces / cm ² ). .

  The (114) plane was adopted as the crystal plane of the aluminum nitride single crystal (substrate) to be measured. This is because the above-described apparatus has a resolution that allows a bright point to be observed sufficiently. Although it is possible to measure a reflected X-ray topographic image using the (103) plane or the (105) plane in addition to the (114) plane, for example, the reflected X-ray topograph of the (103) plane using the above-described apparatus. This is because when the image is acquired, the observation of the bright point becomes unclear because the resolution is insufficient. Therefore, it is preferable that a reflected X-ray topographic image having a resolution higher than that of the measurement conditions described in the present invention can be obtained. However, as far as the present inventor examines, as a lower limit value of practical resolution for measuring a bright spot. Confirms that one pixel is about 10 μm × 10 μm. When measuring at a higher resolution than this, the measurement area of one reflected X-ray topograph image becomes narrow, and it takes time to measure the entire surface of the substrate, which is not preferable. When the measurement surface is different, the diffraction condition changes, so that the bright spot may be observed as a dark spot, but the present inventors have confirmed that the bright spot position matches the dark spot position. Further, when the crystal plane is curved in the substrate surface and deviates from the diffraction conditions at different points on the substrate surface, it is preferable to perform measurement axis alignment of the aluminum nitride single crystal so as to satisfy the diffraction condition at each position. .

The surface of the aluminum nitride single crystal substrate for obtaining the reflected X-ray topographic image is subjected to chemical mechanical polishing (CMP) polishing to remove the polishing damage layer on the surface, and no polishing damage or polishing scratches are observed in the reflected X-ray topographic image. Finished in a state. The surface roughness was finished to a state having a root mean square roughness (RMS) of 0.15 nm or less by ² × 5 μm ² field observation with an atomic force microscope. When there are polishing flaws, the bright point becomes unclear, making it difficult to evaluate the present invention.

Example 1
(Cleaning the base substrate)
A commercially available aluminum nitride single crystal substrate having a diameter of 22 mm and a thickness of 510 μm produced by a sublimation method was used as the base substrate. The aluminum nitride single crystal substrate as the base substrate was ultrasonically cleaned with commercially available acetone and isopropyl alcohol. Further, in order to prevent particles from adhering to the base substrate during transportation, the transportation case was washed with isopropyl alcohol, and the particles were removed by air blow or nitrogen blow.

  After cleaning the base substrate, it was placed on a BN-coated graphite support (susceptor) in the HVPE apparatus (apparatus in FIG. 1) so that the Al polarity side of the aluminum nitride single crystal substrate becomes the growth surface.

(Preparation for production of aluminum nitride single crystal)
The HVPE apparatus used for the growth of the aluminum nitride single crystal was the one shown in FIG. In the embodiment of FIG. 1, an apparatus in which a rectifying partition wall was provided inside the reactor 11 250 mm upstream from the tip of the group III source gas supply nozzle 24 was used. The rectifying partition wall is a quartz glass plate having 24 through-holes with a diameter of 3 mm, and is installed by welding to the inner wall of the reactor 11 made of quartz glass. Extruded carrier gas supplied from the further upstream side of the reactor 11 was circulated through the through-hole of the rectifying partition wall. A hydrogen-nitrogen mixed carrier gas in which hydrogen and nitrogen were mixed at a ratio of 7: 3 was used as the extruded carrier gas, and the total flow rate was 6500 sccm. Further, the pressure in the reactor 11 during the growth was maintained at 0.99 atm.

(Supply of nitrogen source gas: Addition of group V additional halogen gas (advance supply of hydrogen chloride gas))
From the nitrogen source gas supply nozzle 32, a total of 200 sccm (halogen-based gas (hydrogen chloride gas) 20 sccm / total amount (plural gases) 200 sccm) of ammonia gas 20 sccm, hydrogen chloride gas 20 sccm, and hydrogen carrier gas 160 sccm is applied to the reaction zone 10 (base substrate). 12)). At this time, the temperature of the nitrogen source gas supply nozzle 32 was adjusted to 400 ° C. so that ammonia gas and hydrogen chloride gas did not react. Further, 1500 sccm of nitrogen gas was supplied from a barrier gas nozzle (a nozzle arranged so as to be able to supply barrier gas from between the nitrogen source gas supply nozzle 32 and the group III source gas supply nozzle 24 (not shown)). .

(Base substrate temperature)
The base substrate 12 was heated to 1450 ° C. while supplying the plurality of gases of 200 sccm in total from the nitrogen source gas supply nozzle 32 and 1500 sccm of nitrogen gas from the barrier gas nozzle.

(Supply of group III additional halogen gas (previous supply of hydrogen chloride gas))
After heating the base substrate 12 to 1450 ° C., hydrogen chloride gas 7 sccm is supplied from the group III additional halogen-based gas supply nozzle 26, and hydrogen nitrogen mixed carrier gas 1793 sccm is supplied from the source halogen-based gas introduction nozzle 23, so that III A total of 1800 sccm (halogen-based gas (hydrogen chloride gas) 7 sccm / total amount 1800 sccm) of gas was supplied from the group source gas supply nozzle 24. The total flow rate of the gas supplied into the reactor 11 was 10000 sccm.

(Starting growth by supplying Group III source gas)
25 seconds after the start of hydrogen chloride gas supply, 9 sccm of hydrogen chloride gas is introduced from the source halogen gas introduction nozzle 23 and reacted with 6N grade high-purity aluminum heated to 400 ° C. in advance. Was generated. At the same time, the hydrogen-nitrogen mixed carrier gas was reduced by 9 sccm to 1784 sccm. The aluminum chloride gas was supplied onto the base substrate 12 from the group III source gas supply nozzle 24, and crystal growth was started. The hydrogen chloride gas supply amount V _H0 until the group III source gas (aluminum chloride gas) is supplied is V _H0 = V _H = 27 sccm, and the halogen-based gas (hydrogen chloride gas after the group III source gas is supplied) ) Fraction (H _epi ) was 0.90.

(Growth of aluminum nitride single crystal)
An aluminum nitride single crystal was grown for 16 hours at the gas flow rate and base substrate temperature under the above conditions. After the growth of the aluminum nitride single crystal, the supply of aluminum chloride gas, ammonia gas, and hydrogen chloride gas was stopped and cooled to room temperature.

(Evaluation of aluminum nitride single crystal)
Next, in order to remove polycrystalline aluminum nitride particles abnormally grown on the outer periphery of the obtained aluminum nitride single crystal laminated substrate, the side of the grown aluminum nitride single crystal was cut into hexagons each having a length of 9.8 mm. The surface of was flattened by mechanical polishing. Further, the polishing damage layer on the aluminum nitride single crystal surface was removed by CMP polishing. The area of the hexagon was 2.5cm ^2. Thereafter, a reflection X-ray topographic image of the (114) plane of the entire surface of the aluminum nitride single crystal subjected to CMP polishing was obtained.

(Repeated production)
Under the same conditions as described above, an aluminum nitride single crystal was produced 5 times using the same reactor and evaluated. The minimum value of the bright spot density of the obtained aluminum nitride single crystal was 1.5 pieces / cm ² and the maximum value was 5.2 pieces / cm ² . The average value of the light spot density was 2.8 / cm ² , the standard deviation was 1.4 / cm ² , and the standard deviation / average density was 52%. The results are shown in Table 1.

Example 2
As in Example 1, the apparatus shown in FIG. 1 was used. The same operations as in Example 1 were performed for (cleaning of the base substrate) and (preparation for manufacturing an aluminum nitride single crystal).

(Supply of nitrogen source gas: Addition of group V additional halogen gas (advance supply of hydrogen chloride gas))
A total of 200 sccm (halogen gas (hydrogen chloride gas) 120 sccm / total amount (plural gases) 200 sccm) of ammonia gas 20 sccm, hydrogen chloride gas 120 sccm, and hydrogen carrier gas 60 sccm was supplied to the reaction zone 10 from the nitrogen source gas supply nozzle 32. . Nitrogen gas 1500 sccm was supplied from the barrier gas nozzle. At this time, the temperature of the nitrogen source gas supply nozzle 32 was adjusted to 400 ° C. so that ammonia gas and hydrogen chloride gas did not react.

(Base substrate temperature)
The base substrate 12 was heated to 1450 ° C. while supplying the plurality of gases of 200 sccm in total from the nitrogen source gas supply nozzle 32 and 1500 sccm of nitrogen gas from the barrier gas nozzle.

(Supply of group III additional halogen gas (previous supply of hydrogen chloride gas))
After heating the base substrate 12 to 1450 ° C., the hydrogen chloride gas 27 sccm is supplied from the group III additional halogen-based gas supply nozzle 26, and the hydrogen-nitrogen mixed carrier gas 1773 sccm is supplied from the raw material halogen-based gas introduction nozzle 23, whereby III A total of 1800 sccm (halogen-based gas (hydrogen chloride gas) 27 sccm / total amount 1800 sccm) of gas was supplied from the group source gas supply nozzle 24. The total flow rate of the gas supplied into the reactor 11 was 10000 sccm.

(Starting growth by supplying Group III source gas)
25 seconds after the start of hydrogen chloride gas supply, 9 sccm of hydrogen chloride gas is introduced from the source halogen gas introduction nozzle 23 and reacted with 6N grade high-purity aluminum heated to 400 ° C. in advance. Was generated. At the same time, the hydrogen-nitrogen mixed carrier gas was reduced by 9 sccm to 1764 sccm. The aluminum chloride gas was supplied onto the base substrate 12 from the group III source gas supply nozzle 24, and crystal growth was started. The hydrogen chloride gas supply amount V _H0 until the Group III source gas (aluminum chloride gas) is supplied is V _H0 = V _H = 147 sccm, and the halogen-based gas (hydrogen chloride gas after the Group III source gas is supplied) ) Fraction (H _epi ) was 0.98.

(Growth of aluminum nitride single crystal), (Evaluation of aluminum nitride single crystal), (Repeated production) were performed in the same manner as in Example 1. As a result of obtaining a reflected (114) plane X-ray topographic image of the obtained five aluminum nitride single crystals, the minimum value of the bright spot density was 0.5 / cm ² and the maximum value was 2.9 / cm ² . The average value of the light spot density was 1.8 / cm ² , the standard deviation was 1.0 / cm ² , and the standard deviation / average was 59%. The results are shown in Table 1.

Example 3
As in Example 1, the apparatus shown in FIG. 1 was used. The same operations as in Example 1 were performed for (cleaning of the base substrate) and (preparation for manufacturing an aluminum nitride single crystal).

(Nitrogen source gas supply: No additional group V halogen gas)
From the nitrogen source gas supply nozzle 32, ammonia gas 31 sccm and hydrogen chloride gas were not supplied (0 sccm), and a total of 200 sccm of hydrogen carrier gas 169 sccm was supplied to the reaction zone 10 (on the base substrate 12). At this time, the temperature of the nitrogen source gas supply nozzle 32 was set to 400 ° C. Further, 1500 sccm of nitrogen gas was supplied from the barrier gas nozzle.

(Base substrate temperature)
The base substrate 12 was heated to 1500 ° C. while supplying the plurality of gases of 200 sccm in total from the nitrogen source gas supply nozzle 32 and 1500 sccm of nitrogen gas from the barrier gas nozzle.

(Supply of group III additional halogen gas (previous supply of hydrogen chloride gas))
After the base substrate 12 is heated to 1500 ° C., a hydrogen chloride gas of 4.2 sccm is supplied from the group III additional halogen-based gas supply nozzle 26, and a hydrogen-nitrogen mixed carrier gas of 1795.8 sccm is supplied from the source halogen-based gas introduction nozzle 23. Thus, a total of 1800 sccm (halogen-based gas (hydrogen chloride gas) 4.2 sccm / total amount 1800 sccm) of gas was supplied from the group III source gas supply nozzle 24. The total flow rate of the gas supplied into the reactor 11 was 10000 sccm.

(Starting growth by supplying Group III source gas)
25 seconds after the start of hydrogen chloride gas supply, 16.8 sccm of hydrogen chloride gas is introduced from the source halogen-based gas introduction nozzle 23 and reacted with 6N grade high-purity aluminum heated to 400 ° C. in advance. Aluminum gas was generated. At the same time, the hydrogen-nitrogen mixed carrier gas was reduced by 16.8 sccm to 1779 sccm. The aluminum chloride gas was supplied onto the base substrate 12 from the group III source gas supply nozzle 24, and crystal growth was started. The hydrogen chloride gas supply amount V _H0 until the Group III source gas (aluminum chloride gas) is supplied is V _H0 = V _H = 4.2 sccm, and the halogen-based gas (chlorine chloride) after the Group III source gas is supplied. Hydrogen gas) fraction (H _epi ) was 0.43.

(Growth of aluminum nitride single crystal)
An aluminum nitride single crystal was grown for 11 hours at the gas flow rate and base substrate temperature under the above conditions. After the growth of the aluminum nitride single crystal, the supply of aluminum chloride gas, ammonia gas, and hydrogen chloride gas was stopped and cooled to room temperature.

(Evaluation of aluminum nitride single crystal) and (repeated production) were carried out in the same manner as in Example 1. As a result of obtaining a reflection (114) plane X-ray topographic image of the obtained five aluminum nitride single crystals, the minimum value of the bright spot density was 3.6 / cm ² , and the maximum value was 26.0 / cm ² . The average value of the light spot density was 17.1 / cm ² , the standard deviation was 8.3 / cm ² , and the standard deviation / average was 48%. The results are shown in Table 1.

Comparative Example 1
As in Example 1, the apparatus shown in FIG. 1 was used. The same operations as in Example 1 were performed for (cleaning of the base substrate) and (preparation for manufacturing an aluminum nitride single crystal).

(Nitrogen source gas supply: No additional group V halogen gas)
From the nitrogen source gas supply nozzle 32, ammonia gas 20 sccm and hydrogen chloride gas were not supplied (0 sccm), and a total of 200 sccm of hydrogen carrier gas 180 sccm was supplied to the reaction zone 10 (on the base substrate 12). At this time, the temperature of the nitrogen source gas supply nozzle 32 was set to 400 ° C. Further, 1500 sccm of nitrogen gas was supplied from the barrier gas nozzle.

  (Base substrate temperature) was the same as in Example 1. Then, the (Group III additional halogen-based gas supply (preceding supply of hydrogen chloride gas)) of Example 1 was not performed, and the following (Start of growth by supplying Group III source gas) was performed.

(Growth started by supplying Group III source gas)
After heating the base substrate 12 to 1450 ° C., 20 sccm of hydrogen chloride gas was supplied from the nitrogen source gas supply nozzle 32 and the hydrogen carrier gas was reduced to 160 sccm. A total of 200 sccm (halogen-based gas (hydrogen chloride gas) 20 sccm / total amount 200 sccm) was supplied to the reaction zone 10 (on the base substrate 12) without changing the ammonia gas 20 sccm. At this time, the temperature of the nitrogen source gas supply nozzle 32 was set to 400 ° C. Further, 1500 sccm of nitrogen gas was supplied from the barrier gas nozzle. At the same time, 7 sccm of hydrogen chloride gas is supplied from the group III additional halogen-based gas supply nozzle 26, and simultaneously, 9 sccm of hydrogen chloride gas and 1784 sccm of hydrogen-nitrogen mixed carrier gas are supplied from the source halogen-based gas introduction nozzle 23, and 400 ° C. in advance. The aluminum chloride gas was generated by reacting with 6N grade high-purity aluminum that had been heated to a high temperature. As a result, a total of 1800 sccm (halogen-based gas (hydrogen chloride gas) 7 sccm / total amount 1800 sccm) of gas was supplied from the group III source gas supply nozzle 24 to start growth. There was no prior supply of hydrogen chloride (V _H0 = 0 sccm). V _H = 27 sccm and H _epi was 0.90. The total flow rate of the gas supplied into the reactor 11 was 10000 sccm. Comparative Example 1 is a condition in which the preceding supply of hydrogen chloride gas was not performed under the conditions of Example 1.

(Growth of aluminum nitride single crystal), (Evaluation of aluminum nitride single crystal), (Repeated production) were performed in the same manner as in Example 1. As a result of obtaining a reflection (114) plane X-ray topographic image of the obtained five aluminum nitride single crystals, the minimum value of the bright spot density was 3.6 / cm ² , and the maximum value was 28.5 / cm ² . The average value of the light spot density was 9.9 / cm ² , the standard deviation was 10.5 / cm ² , and the standard deviation / average value was 106%. The results are shown in Table 1.

Comparative Example 2
As in Example 1, the apparatus shown in FIG. 1 was used. (Base substrate cleaning), (Preparation of aluminum nitride single crystal production), (Nitrogen source gas supply: V group additional halogen-based gas not added), (Base substrate temperature) are the same as in Example 3. went. Then, the (Group III additional halogen-based gas supply (preceding supply of hydrogen chloride gas)) of Example 3 was not performed, and the following (Start of growth by supplying Group III source gas) was performed.

(Growth started by supplying Group III source gas)
After heating the base substrate 12 to 1500 ° C., 4.2 sccm of hydrogen chloride gas is supplied from the group III additional halogen-based gas supply nozzle 26, and at the same time, 16.8 sccm of hydrogen chloride gas is supplied from the source halogen-based gas introduction nozzle 23. A hydrogen / nitrogen mixed carrier gas of 1779 sccm was supplied and reacted with 6N grade high-purity aluminum heated to 400 ° C. in advance to generate aluminum chloride gas. As a result, a total of 1800 sccm (halogen-based gas (hydrogen chloride gas) 4.2 sccm / total amount 1800 sccm) of gas was supplied from the group III source gas supply nozzle 24 to start growth. There was no prior supply of hydrogen chloride (V _H0 = 0 sccm). V _H = 4.2 sccm and H _epi was 0.43. The total flow rate of the gas supplied into the reactor 11 was 10000 sccm. Comparative Example 2 is a condition in which the preceding supply of hydrogen chloride gas was not performed under the conditions of Example 3.

(Growth of aluminum nitride single crystal), (Evaluation of aluminum nitride single crystal), and (Repeated production) were performed in the same manner as in Example 3. As a result of obtaining a reflection (114) plane X-ray topographic image of the obtained five aluminum nitride single crystals, the minimum value of the bright spot density was 6.0 / cm ² , and the maximum value was 45.2 / cm ² . The average value of the light spot density was 22.8 pieces / cm ² , the standard deviation was 15.0 pieces / cm ² , and the standard deviation / average value was 66%. The results are shown in Table 1.

  The results of the above examples and comparative examples are summarized in Table 1. According to the method of the present invention, a high-quality group III nitride single crystal having a small average value of light spot density, standard deviation, and standard deviation / average value can be repeatedly produced.

10 reaction zone 11 reactor 12 base substrate 13 support (susceptor)
14 Extrusion gas introduction port 15 Exhaust port 16 Raw material part external heating device 17 Growth part external heating device 20 Raw material part reaction zone 21 Raw material part reactor 22 Group III metal raw material 23 Raw material halogen-based gas introduction nozzle 24 Group III raw material gas supply nozzle 25 Group III source gas outlet 26 Group III additional halogen-based gas supply nozzle 27 Group III additional halogen-based gas junction 31 Nitrogen source gas inlet 32 Nitrogen source gas supply nozzle 33 Nitrogen source gas outlet 34 Group V additional halogen-based gas supply Nozzle 35 Group V additional halogen-based gas merging section 36 Pre-supply gas calculation range in reaction zone 100 Group III nitride single crystal production apparatus

Claims (6)

This is a method for producing a group III nitride single crystal on a base substrate by supplying a group III source gas and a nitrogen source gas to the base substrate and reacting them in a reactor equipped with the base substrate. And
Before supplying the group III source gas, a hydrogen halide gas and at least one halogen-based gas selected from a halogen gas are supplied onto the base substrate. Method.   3. The III of claim 1, wherein after supplying the nitrogen source gas onto the base substrate, the halogen-based gas is supplied onto the base substrate, and then a group III source gas is supplied onto the base substrate. A method for producing a group nitride single crystal. Continuously supplying the halogen-based gas; and
When the group III source gas is supplied, when the supply amount of the halogen-based gas in the standard state is V _H (sccm) and the supply amount of the group III source gas in the standard state is V _III (sccm), the following formula ( The method for producing a group III nitride single crystal according to claim 1 or 2, wherein a halogen-based gas and a group III source gas are supplied so as to satisfy 1).
0.5 ≦ V _H / (V _H + V _III ) <1.0 (1)   The method for producing a group III nitride single crystal according to any one of claims 1 to 3, wherein the group III source gas is a gas containing aluminum trichloride gas and the nitrogen source gas is ammonia gas.   The method for producing a group III nitride single crystal according to claim 4, wherein the group III nitride single crystal is an aluminum nitride single crystal.   A method for producing a plurality of group III nitride single crystals by repeatedly performing the method according to claim 1 using the same reactor.

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