JP3923950B2 - Method for producing gallium nitride single crystal, apparatus used therefor, and gallium nitride single crystal obtained by the production method - Google Patents

Description

The present invention relates to a method for producing a gallium nitride single crystal, an apparatus used therefor, and a gallium nitride single crystal obtained by the production method.

  Group III element nitride semiconductors are used, for example, in the field of heterojunction high-speed electronic devices and optoelectronic devices (semiconductor lasers, light-emitting diodes, sensors, etc.), and gallium nitride (GaN) is particularly attracting attention. Conventionally, in order to obtain a single crystal of gallium nitride, the gallium nitride powder is heated to about 1000 ° C. and sublimated, and this is cooled and recrystallized to grow the gallium nitride single crystal. A so-called sublimation method is performed (see, for example, Non-Patent Document 1 and Non-Patent Document 2). However, in the conventional manufacturing method, the growth of gallium nitride accompanied by heating also occurs simultaneously with the growth of the gallium nitride single crystal, and the manufacturing efficiency is poor. This is a problem not only with GaN single crystals but also with AlN single crystals and InN single crystals.

Jpn.J.Appl.Phys., 36, L184-L186, 1997 Journal of Crystal Growth, 237-239 (2002) 922-925

The present invention has been made in view of such circumstances, and an object thereof is to provide a method for producing a gallium nitride single crystal in which the decomposition during crystal growth is suppressed and the production efficiency is improved.

In order to achieve the above object, a first production method of the present invention is a method for producing a gallium nitride single crystal in which a single crystal is grown by crystallizing a vapor obtained from a raw material of the gallium nitride single crystal. A method for producing a gallium nitride single crystal , wherein the vaporized material contains GaH _x and the single crystal is grown under pressure .
The second production method of the present invention, gallium nitride single crystal raw material is heated to a vaporization material was sublimed or evaporated, the vaporized material gallium nitride to grow a single crystal by crystallizing monocrystalline a manufacturing method, the raw material, the presence of hydrogen, heated to sublimation or evaporation to produce said vaporized product, the single crystal growth of the features and gallium nitride single crystal to be performed under a pressure of It is a manufacturing method.

As described above, in the production method of the present invention, by growing a single crystal under pressure, decomposition of the grown single crystal can be suppressed, so that a high growth rate is achieved and crystallinity is improved. be able to. Furthermore, in the production method of the present invention, the resulting single crystal can be grown in a certain direction. For example, in the case of a GaN single crystal, it is desirable that the c-axis (0001) is perpendicular to the substrate and the orientation is aligned in the lateral direction.

In the present invention, group III elements are, for example, Ga, Al, and In. Examples of group III element nitrides include GaN, AlN, and InN. Among these, GaN is preferable.

In the present invention, the raw material is not particularly limited, and examples thereof include GaN powder and Ga . Among these , GaN powder is preferable. For example, when GaN powder is used, since the surface area of the raw material can be increased compared to when Ga (metal) is used, the decomposition amount (evaporation amount) of the raw material can be promoted. Moreover, it is preferable to add the said raw material in the middle of a growth and to perform sublimation or evaporation of a raw material continuously.

In the production method of the present invention, it is preferable that the vaporized material is obtained by heating and sublimating a raw material, and the crystallization is performed by recrystallization by cooling the vaporized material. The crystallization may be performed by reacting the vaporized material with a reactive gas. In the production method of the present invention, the vaporized material is obtained by heating and evaporating a raw material, and the crystallization is performed by reacting the vaporized material with a reactive gas. Is preferred. The vaporized material is preferably obtained by decomposing and evaporating the raw material by heating.

  In the manufacturing method of the present invention, it is preferable that the vaporized material is supplied to a crystal generation region by a carrier gas and the single crystal is grown in the crystal generation region.

  In the manufacturing method of the present invention, the temperature of the raw material (T1 (° C.)) and the temperature of the crystal generation region (T2 (° C.)) are independently controlled, and a relationship of T1> T2 is established. It is preferable. T1 (° C.) is, for example, in the range of 300 ° C. to 2600 ° C., preferably in the range of 900 ° C. to 2000 ° C., and more preferably in the range of 1000 ° C. to 1400 ° C. Moreover, T2 (degreeC) is the range of 300 to 2600 degreeC, for example, Preferably it is the range of 500 to 1600 degreeC, More preferably, it is the range of 800 to 1400 degreeC. The difference between T2 and T1 is, for example, in the range of 5 ° C to 2000 ° C, preferably in the range of 10 ° C to 1000 ° C, and more preferably in the range of 10 ° C to 500 ° C.

It is preferable that a part or all of the vaporized material is, for example, GaH _x .

In the present invention, examples of the carrier gas include N ₂ gas, inert gas (eg, Ar, He, and Ne), hydrogen gas, and the like. You may use together. The carrier gas can be introduced, for example, by causing a gas flow from a lower portion of a raw material supply region (to be described later) toward a crystal generation region. The flow rate of the carrier gas is, for example, 50 sccm to 20000 sccm ({50 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec) to {20000 × 1.01325 × 10 ⁵ (Pa ) × 10 ⁻⁶ (m ³ )} / 60 (sec)), preferably 100 sccm to 10,000 sccm ({100 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ ))} / 60 (Sec) to ({10000 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec)), more preferably 200 sccm to 5000 sccm ({200 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec) to {5000 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec)) Career Material supply amount per time to the crystal formation area by scan, for example, in the range of 0.001mol / h~1mol / h, preferably in the range of 0.005mol / h~0.1mol / h.

In the present invention, the single crystal is preferably grown in an atmosphere of a nitrogen (N) -containing gas. Examples of the atmospheric gas that is the nitrogen (N) -containing gas include nitrogen (N ₂ ) gas and NH ₃ gas, and preferably NH ₃ gas and a mixed gas of both the gases. When the raw material is heated and sublimated, it is preferable to use a mixed gas of NH ₃ and N ₂ as the nitrogen (N) -containing gas, and the raw material is heated and evaporated or heated to decompose and evaporate. In this case, it is preferable to use at least one of N ₂ gas and inert gas. When NH ₃ gas is used as the nitrogen (N) -containing gas, for example, N ₂ gas, inert gas (for example, Ar, He, Ne, etc.), H ₂ gas, and the like are mixed to mix NH ₃ gas. It is preferable to control the ratio. Further, as the nitrogen (N) containing gas, nitrogen (N ₂₎ when using a mixed gas of gas and NH ₃ gas, the mixing ratio (volume ratio), for example, N _2: NH ₃ = 95 to 40 : 5-60, preferably 90-60: 10-40, more preferably 85-70: 15-30.

In the present invention, the reaction gas preferably includes at least NH ₃ gas, and further includes, for example, an inert gas or H ₂ gas. Even when the raw material is heated and sublimated, nitrogen (N) in the reaction gas and the vaporized product may react. The flow rate of the reaction gas is, for example, 30 sccm to 3000 sccm ({30 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec) to {3000 × 1.01325 × 10 ⁵ ( Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec)), preferably 50 sccm to 1000 sccm ({50 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec) to {1000 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec)), more preferably 100 sccm to 500 sccm ({100 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec) to {500 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec)) It is.

In the present invention, the pressure condition is , for example, in the range of more than 1 atm and 10000 atm or less (above 1 × 1.013 × 10 ⁵ Pa and 10000 × 1.013 × 10 ⁵ Pa or less), preferably Is in the range of more than 3 atmospheres and 1000 atmospheres or less (more than 3 × 1.013 × 10 ⁵ Pa and less than 1000 × 1.013 × 10 ⁵ Pa), more preferably more than 10 atmospheres and 500 atmospheres The range is below (over 10 × 1.013 × 10 ⁵ Pa and below 500 × 1.013 × 10 ⁵ Pa).

In the present invention, the heating condition of the raw material is, for example, in the range of 300 ° C. to 2400 ° C., for example, when producing a GaN single crystal, preferably in the range of 800 ° C. to 1500 ° C., more preferably 1000 ° C. It is the range of -1400 degreeC.

In the present invention, in order to introduce impurities into the gallium nitride single crystal, it is preferable that the nitrogen (N) -containing gas contains the impurities. Examples of the impurities include silicon (Si), alumina (Al ₂ O ₃ ) indium (In), aluminum (Al), indium nitride (InN), silicon oxide (SiO ₂ ), and indium oxide (In ₂ O ₃ ). Zinc (Zn), magnesium (Mg), zinc oxide (ZnO), magnesium oxide (MgO), germanium (Ge), and the like.

  In the present invention, it is preferable to prepare a group III element nitride in advance, use this as a nucleus for crystal growth, and grow the single crystal on this surface.

In the present invention, the group III element nitride serving as a nucleus may be a single crystal or may be amorphous. Further, the form of the single crystal serving as a nucleus is not particularly limited, but for example, the form of a thin film is preferable. This thin film may be formed on a substrate. Examples of the material of the substrate include amorphous gallium nitride (GaN), amorphous aluminum nitride (AlN), sapphire, silicon (Si), gallium / arsenic (GaAs), gallium nitride (GaN), and aluminum nitride (AlN). ), Silicon carbide (SiC), boron nitride (BN), lithium gallium oxide (LiGaO ₂ ), zirconium boride (ZrB ₂ ), zinc oxide (ZnO), various glasses, various metals, boron phosphide (BP), MoS ₂ , LaAlO ₃ , NbN, MnFe ₂ O ₄ , ZnFe ₂ O ₄ , ZrN, TiN, gallium phosphide (GaP), MgAl ₂ O ₄ , NdGaO ₃ , LiAlO ₂ , ScAlMgO ₄ and Ca ₈ La ₂ (PO ₄ ) There are ₆ O _2, etc., among this, III group element nitride films are preferred. The thickness of the thin film serving as a nucleus is not particularly limited, and is, for example, in the range of 0.0005 μm to 100,000 μm, preferably 0.001 μm to 50000 μm, and more preferably 0.01 μm to 5000 μm. The group III element nitride single crystal thin film can be formed on the substrate by, for example, metal organic chemical vapor deposition (MOCVD), hydride vapor deposition (HVPE), molecular beam epitaxy (MBE) or the like. Moreover, since the thing which formed the gallium nitride thin film on the board | substrate is marketed, you may use it. The maximum diameter of the thin film is, for example, 2 cm or more, preferably 3 cm or more, more preferably 5 cm or more, and the larger the better, the upper limit is not limited. Further, since the standard of the bulk compound semiconductor is 2 inches, from this viewpoint, the maximum diameter of the bulk compound semiconductor is preferably 5 cm. In this case, the range of the maximum diameter of the thin film is, for example, 2 cm. -5 cm, preferably 3 cm-5 cm, more preferably 5 cm. The maximum diameter is a line connecting a point on the outer periphery of the thin film surface with other points and is the length of the longest line.

  It is preferable that the reaction gas flows on the group III element nitride prepared in advance in the crystal generation region. The reaction gas is preferably flowed to the substrate at a certain angle from the horizontal, horizontal, or oblique directions of the group III element nitride prepared in advance.

  In the present invention, a single crystal may be grown directly on the surface of the substrate without forming the thin film.

In the present invention, the growth rate of the gallium nitride single crystal is, for example, 100 μm / h or more, preferably 500 μm / h or more, more preferably 1000 μm / h or more. The growth rate can be controlled, for example, by increasing the pressure of the atmospheric gas, lowering the substrate temperature, or increasing the raw material temperature in the raw material supply region. The growth rate means the thickness of the gallium nitride single crystal grown per hour. The thickness of the gallium nitride single crystal is a value obtained by averaging the unevenness of the SEM image of the crystal cross section.

The manufacturing apparatus of the present invention is an apparatus for manufacturing a gallium nitride single crystal used in the manufacturing method of the present invention, and includes an apparatus for heating the raw material and a pressing means for growing the single crystal. For example, a general heater can be used as the heating unit, and examples of the pressurizing unit include a unit that pressurizes with a supply gas (for example, a carrier gas, an atmospheric gas, a reactive gas, etc.).

  It is preferable that the apparatus further includes means for flowing and crystallizing the reaction gas to the raw material, further including a raw material supply region and a crystal generation region, and the heating means and the carrier in the raw material supply region. It is preferable that a gas introduction unit is disposed, and the reaction gas introduction unit is disposed in the crystal generation region.

In the manufacturing apparatus of the present invention, it is preferable that the raw material supply region and the crystal generation region are separated by a baffle. By separating the raw material supply region and the crystal generation region, it is possible to prevent mixing of raw materials and group III nitrides from the crystal generation region to the raw material supply region. As a result, the gallium nitride single crystal in the crystal generation region Can be more efficiently reduced.

Next, the gallium nitride single crystal of the present invention is obtained by the production method of the present invention.

The full width at half maximum of the gallium nitride single crystal of the present invention is, for example, in the range of 10 seconds to 1000 seconds, and preferably in the range of 30 seconds to 300 seconds. The full width at half maximum can be obtained, for example, from the result of ω scan measurement using an X-ray analyzer.

Next, examples of the semiconductor device using the gallium nitride transparent single crystal of the present invention include a field effect transistor, a light emitting diode (LED), a semiconductor laser (LD), and an optical sensor. It is not limited to these. In addition to these, there is a semiconductor device using the single crystal of the present invention, for example, a semiconductor device having a simple structure in which a p-type semiconductor and an n-type semiconductor are simply joined. There are a device using a single crystal (for example, a pnp transistor, an npn transistor, an npnp thyristor, etc.), a semiconductor device using the single crystal of the present invention as an insulating layer, an insulating substrate, or an insulating semiconductor. The semiconductor device of the present invention can be manufactured by combining the manufacturing method of the present invention and a conventional method. For example, a GaN substrate may be manufactured by the manufacturing method of the present invention, and a semiconductor layer may be stacked thereon by MOCVD or the like. In addition, a semiconductor layer can be formed by the manufacturing method of the present invention. That is, first, an n-type GaN layer is formed by the manufacturing method of the present invention in a nitrogen (N) -containing gas atmosphere, and a p-type GaN layer is formed thereon in the same manner as described above except that the material is changed. A pn junction semiconductor device can be manufactured. In this way, field effect transistors, LEDs, LDs, semiconductor optical sensors, and other semiconductor devices can be manufactured. However, the semiconductor device of the present invention is not limited to the manufacturing method described above, and can be manufactured by other manufacturing methods.

  Next, an example of the production method of the present invention will be described with reference to FIG.

FIG. 1 shows an example of a manufacturing apparatus used in the present invention. As shown in the figure, a crucible 1 is placed in a heat and pressure resistant reaction vessel (not shown) and filled with a single crystal raw material (for example, GaN powder, Ga metal, etc.) 2. The crucible 1 is not particularly limited, and for example, a BN crucible, an AlN crucible, an alumina crucible, a SiC crucible, a graphite crucible, a crucible made of a carbon-based material such as diamond-like carbon, or the like can be used. A substrate 3 is disposed above the crucible 1. The distance between the substrate 3 and the raw material 2 is, for example, 2 mm to 200 mm, preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm. Then, while heating the crucible 1 to about 1000 ° C., the heat in the pressure vessel, introducing a mixed gas of NH ₃ gas and N ₂ gas, a pressure of about 5 atm ⁽⁵ × 1.013 × 10 5 Pa ) The raw material 2 is sublimated or decomposed and evaporated by heating to become gas. On the surface of the substrate 3, the decomposed raw material reacts with the reaction gas to be crystallized, or GaN is cooled and recrystallized to grow a single crystal on the surface of the substrate 3. Since the pressure is applied during the crystal growth, decomposition of gallium nitride is suppressed, and the single crystal is grown in a certain direction.

  Next, FIG. 2A shows another example of the manufacturing apparatus of the present invention. As shown in the figure, in this apparatus, a heating container 22 is disposed in a pressure-resistant chamber 21, and a crucible 28 can be accommodated in the heating container 22. A raw material heating heater 27 is embedded in the lower wall of the heating container 22, and a substrate 32 can be attached to the upper ceiling of the heating container 22 via a holder and a substrate heater 26. ing. As shown in FIG. 2B, the crucible 28 has a through hole c at the center thereof. When this crucible 28 is disposed in the heating container 22, the carrier gas introduction pipe 24 is disposed in a state of being aligned with the through hole c and penetrating the lower part of the heating container 22 and the pressure-resistant chamber 21, and A baffle 31 is disposed on the upper portion of the crucible 28, thereby separating the raw material supply region 29 and the crystal generation region 30. Then, the reaction gas introduction tube 23 is arranged in a state of penetrating the side wall of the heating vessel 22 and the pressure-resistant chamber 21 (the upper right side wall in the figure) so that the tip thereof is positioned near the attachment portion of the substrate 32. Yes. In the figure, the reaction gas introduction pipe 23 is installed in the horizontal direction. However, if the reaction gas is installed obliquely at an angle and the reaction gas is directly supplied to the substrate, the reaction gas is efficiently supplied to the substrate 32. Since it is supplied, it is more preferable. Moreover, the thermocouple 25 is arrange | positioned in the state which penetrated the lower side wall (left side lower side wall in the same figure) of the heating container 22 and the pressure | voltage resistant chamber 21. As shown in FIG.

An example of a method for producing a gallium nitride single crystal using this apparatus will be described. That is, first, a substrate 32 (for example, a sapphire substrate, a nitride semiconductor substrate, etc.) is attached to the substrate heater 26, a crystal raw material 33 such as GaN powder is placed in the crucible 28, and this is disposed at a predetermined position inside the heating vessel 22. To do. In this state, the crucible 28 is heated by the raw material heater 27 (for example, 1000 ° C.), and a carrier gas (arrow b in the figure) is flowed from the introduction tube 24 toward the substrate 32 through the through hole c of the crucible 28. In addition, a reaction gas (ammonia (NH ₃ ) -containing gas) is caused to flow from the introduction tube 23 to the vicinity of the surface of the substrate 32 (arrow a in the figure) to react the raw material with nitrogen (N) in the reaction gas. The inside of the heating container 22 is in a pressurized state (about 5 atm (5 × 1.013 × 10 ⁵ Pa)).
Then, the heated GaN powder is decomposed and thermally decomposed into Ga and N as shown in the following formula (1). However, when hydrogen (H ₂ ) is contained in the atmosphere gas, the carrier gas, and the reaction gas, GaN is decomposed to generate Ga as in the following formulas (3) and (4), and the Ga and the above-mentioned Reaction with hydrogen (H ₂ ) generates GaH _x , GaN _x H, and the like. This is because the activation energy of GaH _x is smaller than the activation energy of Ga. Since these act as intermediate products, the decomposition reaction and evaporation process of the raw materials are promoted, which is preferable. Further, even when Ga metal is used as a raw material, for example, GaH _x or the like is generated as in the following formula (4).
Then, the carrier gas flows from the raw material supply region 29 toward the crystal generation region 30 near the surface of the substrate 32, where ammonia (NH ₃ ) in the reaction gas reacts with the generated radical nitrogen to crystallize, As a result, the GaN single crystal is grown on the surface of the substrate 32. The reaction between decomposed Ga and ammonia (NH ₃ ) in the reaction gas is represented by the following formula (2), and the reaction between GaH _x and ammonia (NH ₃ ) in the reaction gas is as follows: It is as Formula (5).
GaN → Ga + (1/2) N ₂ (1)
Ga + NH ₃ → GaN + (3/2) H ₂ (2)
GaN + (3/2) H ₂ → Ga + NH ₃ (3)
Ga + (x / 2) H ₂ → GaH _x (4)
_{GaH x + NH 3 → GaN +} ((3 + x) / 2) H 2 (5)

  In addition, it is preferable to form a GaN thin film on the surface of the substrate 32 by MOCVD method or HVPE method in advance.

In this way, the gallium nitride single crystal of the present invention is obtained by the manufacturing method other than the production method of the present invention may be produced gallium nitride single crystal of the present invention.

  Next, examples of the present invention will be described together with comparative examples. In the following examples and comparative examples, the sublimation method is a method in which a raw material is sublimated by heating, cooled and recrystallized, the raw material is heated to decompose, evaporate, react with a reaction gas, and crystallize. And a method of heating and evaporating the raw material and reacting with the reaction gas to crystallize.

(Reference Examples 1-1 to 1-7)
As shown in FIG. 1, a crucible 1 was placed in a heat-resistant pressure-resistant reaction vessel (not shown) and filled with a single crystal raw material (GaN powder) 2. A substrate 3 was disposed above the crucible 1. The crucible 1 is heated, and a mixed gas of NH ₃ and N ₂ is introduced into the heat-resistant pressure-resistant container and pressurized to 5 atm (5 × 1.013 × 10 ⁵ Pa), so Crystals were grown on the surface of the substrate 3 by a sublimation method. The growth conditions are as follows: GaN powder raw material 2 g, distance between substrate and raw material 140 mm, substrate material: sapphire, supplied NH ₃ flow rate (10% NH ₃ gas): 50 sccm ({50 × 1.01325 × 10 ⁵ (Pa) × 10 ^-6 (m ³ )} / 60 (sec)). In the growth of this single crystal, as shown in Table 1 below, in Reference Examples 1-1 to 1-4, the growth temperature was changed in the range of 1000 ° C. to 1090 ° C. As shown in Table 2 below, in Reference Examples 1-5 to 1-7, the growth temperature was kept constant at 1000 ° C., and the NH ₃ gas concentration and the gas flow rate were changed to grow the gallium nitride single crystal.

  The gallium nitride single crystals of Reference Examples 1-1 to 1-7 thus obtained were observed with a scanning electron microscope (SEM), and the average thickness (average film thickness) was determined. The results are shown in Table 1 and Table 2 below. Further, the SEM photograph of Reference Example 1-1 is shown in FIG. 10 (crystal surface SEM image) and FIG. 11 (crystal cross-sectional SEM image), and the SEM photograph of Reference Example 1-2 is shown in FIG. 12 (crystal surface SEM image) and FIG. 13 (crystal cross-sectional SEM image), the SEM photograph of Reference Example 1-3 is shown in FIG. 14 (crystal surface SEM image) and FIG. 15 (crystal cross-sectional SEM image), and the SEM photograph of Reference Example 1-4 is shown in FIG. (Crystal surface SEM image) and FIG. 17 (Crystal cross section SEM image), and SEM photographs of Reference Example 1-5 are shown in FIG. 18 (Crystal surface SEM image) and FIG. 19 (Crystal cross section SEM image). SEM photographs of -6 are shown in FIG. 20 (crystal surface SEM image) and FIG. 21 (crystal cross section SEM image), and SEM photographs of Reference Example 1-7 are shown in FIG. 22 (crystal surface SEM image) and FIG. Image). The single crystal was also subjected to X-ray diffraction (XRD) measurement. FIG. 3 shows the XRD measurement result of Reference Example 1-1, FIG. 4 shows the XRD measurement result of Reference Example 1-2, FIG. 5 shows the XRD measurement result of Reference Example 1-3, and XRD measurement of Reference Example 1-4. The results are shown in FIG. 6, the XRD measurement results of Reference Example 1-5 are shown in FIG. 7, the XRD measurement results of Reference Example 1-6 are shown in FIG. 8, and the XRD measurement results of Reference Example 1-7 are shown in FIG. . The average film thickness measurement is a value obtained by averaging the unevenness of the SEM image of the crystal cross section, and the XRD measurement is based on 2θ-ω scan measurement using an X-ray analyzer.

なお、前記表２中のガス流量（ｓｃｃｍ）は、「×１．０１３２５×１０⁵（Ｐａ）×１０^-6（ｍ³）」／６０（ｓｅｃ）」の換算式を用いることで、ＳＩ単位になおすことができる。

In addition, the gas flow rate (sccm) in the said Table 2 is SI unit by using the conversion formula of "* 1.01325 * 10 < ⁵ > (Pa) * 10 < ^-6 > (m < ³ >)" / 60 (sec) ". Can be corrected.

  As shown in Table 1 and Table 2, in Reference Examples 1-1 to 1-7, the average film thickness of the single crystal was larger than Comparative Examples 1-1 to 1-10 described later. Further, as shown in the XRD measurement results of FIGS. 3 to 9, the obtained single crystal is grown in a certain direction. In particular, in the single crystal of Reference Example 1-6, almost complete c Axial orientation was shown.

(Comparative Examples 1-1 to 1-10)
As shown in FIG. 1, a crucible 1 was placed in a heat-resistant pressure-resistant reaction vessel (not shown) and filled with a single crystal raw material (GaN powder) 2. A substrate 3 was disposed above the crucible 1. Then, the crucible 1 is heated, and a mixed gas of NH ₃ and N ₂ is introduced into the heat-resistant pressure-resistant vessel, and a gallium nitride single crystal is sublimated by atmospheric sublimation under the atmospheric pressure condition (without pressurization). Nurtured above. The growth conditions are as follows: GaN powder raw material 2 g, distance between substrate and raw material 35 mm, substrate material: sapphire, NH ₃ flow rate (10% NH ₃ gas): 50 sccm ({50 × 1.01325 × 10 ⁵ (Pa) × 10 ^-6 (m ³ )} / 60 (sec)). In the growth of this single crystal, as shown in Table 3 below, in Comparative Examples 1-1 to 1-6, the growth temperature was changed in the range of 950 ° C. to 1100 ° C. As shown in Table 4 below, in Comparative Examples 1-7 to 1-10, the growth temperature was kept constant at 1000 ° C., and the NH ₃ gas concentration and the gas flow rate were changed to grow gallium nitride single crystals.

  The growth results (average film thickness) of the gallium nitride single crystals of Comparative Examples 1-1 to 1-10 are shown in Tables 3 and 4 below. The average film thickness was measured in the same manner as in Reference Example 1. Moreover, the SEM photograph of the single crystal of Comparative Example 1-3 is shown in FIG. 27 (crystal surface SEM image) and FIG. 28 (crystal cross-sectional SEM image), and the SEM photograph of the single crystal of Comparative Example 1-8 is shown in FIG. (Crystal surface SEM image) and a SEM photograph of the single crystal of Comparative Example 1-9 is shown in FIG. 30 (Crystal surface SEM image). And it carried out similarly to the Example, and performed the XRD measurement about the single crystal of Comparative Examples 1-3, 1-8, and 1-9. The XRD measurement result of Comparative Example 1-3 is shown in FIG. 24, the XRD measurement result of Comparative Example 1-8 is shown in FIG. 25, and the XRD measurement result of Comparative Example 1-9 is shown in FIG.

なお、前記表４中のガス流量（ｓｃｃｍ）は、「×１．０１３２５×１０⁵（Ｐａ）×１０^-6（ｍ³）」／６０（ｓｅｃ）」の換算式を用いることで、ＳＩ単位になおすことができる。

Note that the gas flow rate (sccm) in Table 4 is expressed in SI units by using a conversion formula of “× 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )” / 60 (sec) ”. Can be corrected.

  As shown in Table 3 and Table 4, in Comparative Examples 1-1 to 1-10, it was only Comparative Examples 1-3, 1-8 and 1-9 that the generation of single crystals could be confirmed. Even the single crystal of Comparative Example 1-3 having the largest thickness was smaller than all the single crystals obtained in Reference Example 1. Further, as shown in the XRD measurement results of FIGS. 24 to 26, the growth direction of the single crystal of the comparative example was random.

(Examples 1-1 to 1-3)
As shown in FIG. 2A, a crucible 28 was placed in the pressure-resistant chamber 21 and filled with a single crystal raw material (GaN powder) 33. The growth conditions are as follows: GaN powder 4 g, distance between substrate and raw material 140 mm, carrier gas (N ₂ : 95%, H ₂ : 5%, flow rate: 200 sccm ({200 × 1.01325 × 10 ⁵ (Pa) × 10 ^{− 6} (m ³ )} / 60 (sec))), raw material temperature 1150 ° C., atmospheric gas (N ₂ : 100%), reaction gas (NH ₃ : 100%, flow rate: 200 sccm ({200 × 1.01325 × 10 ⁵ (Pa) × 10 ⁻⁶ (m ³ )} / 60 (sec))) and a growth time of 30 min. H ₂ gas promotes decomposition and evaporation of GaN. As the atmospheric gas, to the NH ₃ to N ₂ may contain or may be an inert gas such as Ar. Further, N ₂ or inert gas may be contained in the reaction gas. In this condition, the pressure of the pressure chamber 21 5 atm (5 × 1.013 × 10 ⁵ Pa) pressurized, 900 ° C. The substrate temperature (Example 1 -1), 1000 ° C. (Example 1 -2) A gallium nitride single crystal was grown at 1100 ° C. (Example 1-3 ).

( Comparative Examples 2-1 to 2-3 )
As Comparative Examples 2-1 to 2-3 , the pressure in the pressure-resistant chamber 21 is atmospheric pressure (no pressurization), and the substrate temperatures are 900 ° C. ( Comparative Example 2-1) and 970 ° C. ( Comparative Example 2-2). ) A gallium nitride single crystal was grown in the same manner as in Example 2 except that the temperature was 1020 ° C. ( Comparative Example 2-3 ).

Example 1 -1 1 -3 and Comparative Example 2 -1 2 -3 growth of gallium nitride single crystal results (average film thickness), shown in Table 5 below. The average film thickness was measured in the same manner as in Reference Example 1. Further, an SEM photograph of the single crystal of Example 1 -1, shown in FIG. 31 (crystal cross-sectional SEM image), the SEM photograph of the single crystal of Example 1 -2, shown in FIG. 32 (crystal cross-sectional SEM image), Example 1-3 A SEM photograph of single crystal is shown in FIG. 33 (crystal cross-sectional SEM image). The SEM photograph of the single crystal of Comparative Example 2 -1, shown in FIG. 34 (crystal cross-sectional SEM image), the SEM photograph of the single crystal of Comparative Example 2-2, shown in FIG. 35 (crystal cross-sectional SEM image), Comparative Example A SEM photograph of the 2-3 single crystal is shown in FIG. 36 (crystal cross-sectional SEM image).

As shown in Table 5, even the most thickness greater Comparative Example 2 -1 and 2 -2 single crystal, Example 1 -1 was equal to or smaller as the single crystal of 1 -2 and 1 -3 . Further, the crystals obtained in Example 1-3 exhibited excellent crystallinity among the examples.

In FIG. 37, the GaN film formed on the sapphire substrate by MOCVD is heated for 15 minutes at various temperatures, atmospheric pressure conditions (no pressure applied), or 5 atmospheric pressure (5 × 1.013 × 10 ⁵ Pa)), The result of estimating the decomposition rate of GaN from the reduction amount of the grown film thickness is shown. From the results, it was found that the decomposition rate of GaN was greatly reduced in a pressurized atmosphere (5 atm (5 × 1.013 × 10 ⁵ Pa)).

FIG. 38 shows the substrate temperature and growth rate when a GaN single crystal is grown under atmospheric pressure conditions (without pressure) and when a GaN single crystal is grown at 5 atm (5 × 1.013 × 10 ⁵ Pa). The relationship is shown. When grown in a pressurized atmosphere (5 atm (5 × 1.013 × 10 ⁵ Pa)), a high growth rate of a GaN single crystal of 130 μm / h at maximum was obtained. From this result, it was found that the crystal growth in a pressurized atmosphere suppresses the decomposition of GaN on the substrate, and a high growth rate can be obtained.

FIG. 39 shows the results of ω scan measurement using an X-ray analyzer. When the full width at half maximum was determined, it was 3546 seconds for a GaN single crystal grown under atmospheric pressure conditions (no pressure applied), whereas a GaN single crystal grown at 5 atmospheric pressure (5 × 1.013 × 10 ⁵ Pa). Then, it was 1155 seconds. It was shown that the GaN crystal grown in a pressurized atmosphere (5 atm (5 × 1.013 × 10 ⁵ Pa)) is improved in terms of crystallinity.

  As described above, according to the production method of the present invention, it is possible to produce a group III element nitride single crystal while suppressing decomposition during crystal growth. Therefore, the production method of the present invention is excellent in production efficiency. Further, according to the production method of the present invention, the group III element nitride single crystal can be grown in a certain direction, so that the obtained single crystal has high quality.

FIG. 1 is a schematic diagram showing an example of the configuration of an apparatus used in the manufacturing method of the present invention. FIG. 2A is a schematic diagram illustrating an example of the configuration of an apparatus used in the manufacturing method of the present invention, and FIG. 2B is a perspective view illustrating an example of a crucible used in the manufacturing method of the present invention. FIG. 3 is a graph showing the XRD measurement results of Reference Example 1-1 of the present invention. FIG. 4 is a graph showing the XRD measurement results of Reference Example 1-2 of the present invention. FIG. 5 is a graph showing the XRD measurement results of Reference Example 1-3 of the present invention. FIG. 6 is a graph showing the XRD measurement results of Reference Example 1-4 of the present invention. FIG. 7 is a graph showing the XRD measurement results of Reference Example 1-5 of the present invention. FIG. 8 is a graph showing the XRD measurement results of Reference Example 1-6 of the present invention. FIG. 9 is a graph showing the XRD measurement results of Reference Example 1-7 of the present invention. FIG. 10 is an SEM photograph (crystal surface SEM image) of Reference Example 1-1 of the present invention. FIG. 11 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-1 of the present invention. FIG. 12 is an SEM photograph (crystal surface SEM image) of Reference Example 1-2 of the present invention. FIG. 13 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-2 of the present invention. FIG. 14 is an SEM photograph (crystal surface SEM image) of Reference Example 1-3 of the present invention. FIG. 15 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-3 of the present invention. FIG. 16 is an SEM photograph (crystal surface SEM image) of Reference Example 1-4 of the present invention. FIG. 17 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-4 of the present invention. FIG. 18 is an SEM photograph (crystal surface SEM image) of Reference Example 1-5 of the present invention. FIG. 19 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-5 of the present invention. FIG. 20 is an SEM photograph (crystal surface SEM image) of Reference Example 1-6 of the present invention. FIG. 21 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-6 of the present invention. FIG. 22 is an SEM photograph (crystal surface SEM image) of Reference Example 1-7 of the present invention. FIG. 23 is an SEM photograph (crystal cross-sectional SEM image) of Reference Example 1-7 of the present invention. FIG. 24 is a graph showing the XRD measurement results of Comparative Example 1-3. FIG. 25 is a graph showing the XRD measurement results of Comparative Example 1-8. FIG. 26 is a graph showing the XRD measurement results of Comparative Example 1-9. FIG. 27 is an SEM photograph (crystal surface SEM image) of Comparative Example 1-3. FIG. 28 is an SEM photograph (crystal cross-sectional SEM image) of Comparative Example 1-3. FIG. 29 is an SEM photograph (crystal surface SEM image) of Comparative Example 1-8. FIG. 30 is an SEM photograph (crystal surface SEM image) of Comparative Example 1-9. Figure 31 is a SEM photograph of Example 1 -1 (crystal cross-sectional SEM image). FIG. 32 is an SEM photograph (crystal cross-sectional SEM image) of Example 1-2 . FIG. 33 is an SEM photograph (crystal cross-sectional SEM image) of Example 1-3 . FIG. 34 is an SEM photograph (crystal cross-sectional SEM image) of Comparative Example 2-1. FIG. 35 is an SEM photograph (crystal SEM image) of Comparative Example 2-2. FIG. 36 is an SEM photograph (crystal cross-sectional SEM image) of Comparative Example 2-3 . FIG. 37 is a graph showing an example of the relationship between the substrate temperature and the decomposition rate. FIG. 38 is a graph showing an example of the relationship between the substrate temperature and the growth rate. FIG. 39 is a graph showing an example of the result of ω scan measurement using an X-ray analysis apparatus.

Explanation of symbols

1, 28 Crucible 2, 33 GaN powder 3, 32 Substrate 21 Pressure-resistant chamber 22 Heating vessel 23 Reaction gas introduction tube 24 Carrier gas introduction tube 25 Thermocouple 26 Substrate heater 27 Material heater 29 Material supply region 30 Crystal generation region 31 Baffle a, b Gas introduction direction c Through hole

Claims (33)

A method for producing a gallium nitride single crystal, wherein a single crystal is grown by crystallizing a vapor obtained from a raw material of the gallium nitride single crystal,
The method for producing a gallium nitride single crystal, wherein the vaporized material contains GaH _x and the single crystal is grown under pressure . A method for producing a gallium nitride single crystal in which a raw material of a gallium nitride single crystal is heated to sublimate or evaporate to form a vapor, and the single crystal is grown by crystallizing the vapor.
A method for producing a gallium nitride single crystal, wherein the raw material is heated in the presence of hydrogen to be sublimated or evaporated to produce the vaporized product, and the single crystal is grown under pressure . The manufacturing method according to claim 2, wherein the vaporized material contains GaH _x . The manufacturing method according to any one of claims 1 to 3, wherein the raw material is at least one of Ga and GaN powder. The vaporized product is obtained by heating or sublimating or evaporating the raw material, and the crystallization includes recrystallization by cooling the vaporized product and reacting the vaporized product with a reactive gas. The manufacturing method as described in any one of Claim 1 to 4 performed by at least one. The production method according to claim 1, wherein the raw material is decomposed by heating and evaporated. The manufacturing method according to claim 1, wherein the vaporized material is supplied to a crystal generation region by a carrier gas, and the single crystal is grown in the crystal generation region. 8. The single crystal is grown by controlling the heating temperature (T1 (° C.)) of the raw material and the heating temperature (T2 (° C.)) of the crystal generation region independently and T1> T2. The manufacturing method as described in. The carrier gas is N ₂ The production method according to claim 7 or 8, comprising at least one selected from the group consisting of a gas, an inert gas, and hydrogen gas. The manufacturing method according to claim 1, wherein the single crystal is grown in an atmosphere of a nitrogen (N) -containing gas. The nitrogen (N) -containing gas is NH _Three And N ₂ Mixed gas with N ₂ The production method according to claim 10, which is selected from the group consisting of a gas and an inert gas. The reaction gas is at least NH _Three Containing gas, and N ₂ The production method according to any one of claims 5 to 11, comprising at least one of a gas and an inert gas. The pressurization condition is over 1 atm and 500 atm or less (1 × 1.013 × 10 ^Five Over Pa and 500 × 1.013 × 10 ^Five The manufacturing method according to any one of claims 1 to 12, which is in a range of Pa or less. The manufacturing method as described in any one of Claims 1-13 including heating the said raw material on the heating conditions of the range of 300 to 2400 degreeC. The manufacturing method according to claim 1, comprising continuously performing sublimation or evaporation of the raw material. The manufacturing method according to any one of claims 10 to 15, wherein the impurity is contained in the nitrogen (N) -containing gas in order to introduce the impurity into the manufactured gallium nitride single crystal. The production method according to any one of claims 1 to 16, wherein a group III element nitride is prepared in advance, which is used as a nucleus for crystal growth, and the single crystal is grown on the surface. The production method according to claim 17, wherein the group III element nitride serving as a nucleus is single crystal or amorphous. The manufacturing method according to claim 17 or 18, wherein the group III element nitride serving as a nucleus is in the form of a thin film. The manufacturing method according to claim 19, wherein the thin film is formed on a substrate. The manufacturing method according to any one of claims 17 to 20, wherein the maximum diameter of the group III element nitride serving as a nucleus is 2 cm or more. The manufacturing method according to any one of claims 17 to 20, wherein the maximum diameter of the group III element nitride serving as a nucleus is 3 cm or more. The manufacturing method according to any one of claims 17 to 20, wherein the maximum diameter of the group III element nitride serving as a nucleus is 5 cm or more. The manufacturing method according to any one of claims 1 to 23, wherein the single crystal is grown on a substrate. The substrate is amorphous gallium nitride (GaN), amorphous aluminum nitride (AlN), sapphire, silicon (Si), gallium arsenide (GaAs), gallium nitride (GaN), aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), lithium gallium oxide (LiGaO) ₂ ), Zirconium boride (ZrB) ₂ ), Zinc oxide (ZnO), glass, metal, boron phosphide (BP), MoS ₂ LaAlO _Three , NbN, MnFe ₂ O _Four ZnFe ₂ O _Four , ZrN, TiN, gallium phosphide (GaP), MgAl ₂ O _Four , NdGaO _Three LiAlO ₂ , ScAlMgO _Four And Ca ₈ La ₂ (PO _Four ) ₆ O ₂ The manufacturing method according to claim 24, wherein the substrate is made of at least one material selected from the group consisting of: The production method according to any one of claims 1 to 25, wherein a growth rate of the gallium nitride single crystal is 100 µm / h or more. 27. The manufacturing method according to any one of claims 7 to 26, wherein the reaction gas is flowed on a group III element nitride prepared in advance in the crystal generation region. An apparatus for producing a gallium nitride single crystal used in the production method according to any one of claims 1 to 27,
The manufacturing apparatus which has a heating means of the said raw material, and a pressurizing means of the growth atmosphere of the said single crystal. 29. The manufacturing apparatus according to claim 28, further comprising means for causing the reaction gas to flow and crystallize into the raw material. Furthermore, it has a raw material supply area | region and a crystal production | generation area | region, The said heating means and the said carrier gas introduction means are arrange | positioned at the said raw material supply area | region, The said reactive gas introduction means is arrange | positioned at the said crystal production area | region. The manufacturing apparatus according to 28 or 29. The manufacturing apparatus according to claim 30, wherein the raw material supply region and the crystal generation region are separated by a baffle. A gallium nitride single crystal produced by the production method according to any one of claims 1 to 27. A semiconductor device comprising the gallium nitride single crystal according to claim 32.

Images