JP2012046423A - Method for producing group iii nitride-based compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deposition of miscellaneous crystals on the nitrogen-face of a GaN self-standing substrate and waste of raw materials in GaN production by the flux method.SOLUTION: Four arrangements of crucibles 26-1 to 26-4 and a GaN self-standing substrate are exemplified. In FIG. 1.A, the nitrogen-face of a self-standing substrate 10 comes into close contact with an obliquely upward facing flat inner wall of a crucible 26-1. In FIG. 1.B, the nitrogen-face of a self-standing substrate 10 comes into close contact with a horizontally facing flat inner wall of a crucible 26-2, and is fixed by means of a jig ST-2. In FIG. 1.C, a jig ST-3 is disposed on a flat bottom of a crucible 26-3, and self-standing substrates 10-1, 10-2 are fixed so that the nitrogen-faces of the substrates come into close contact with each other. In FIG. 1.D, a jig ST-4 is disposed on a flat bottom of a crucible 26-4, and a GaN self-standing substrate 10 is fixed. The nitrogen-face of the self-standing substrate 10 is covered with the jig ST-4. A flux mixture of molten gallium and sodium is filled in each crucible, and a GaN single crystal is grown on a gallium-face Fin pressurized nitrogen.

Description

The present invention relates to a group III nitride compound semiconductor by reacting a group III element of gallium (Ga), aluminum (Al) or indium (In) with nitrogen (N) in a mixed flux having an alkali metal. The present invention relates to a method for producing a group III nitride compound semiconductor by a so-called flux method. In the present application, the group III nitride compound semiconductor is a semiconductor represented by Al _x Ga _y In _1-xy N (where x, y, and x + y are all 0 or more and 1 or less), n-type / p-type, etc. For which any element is added. Furthermore, it includes those in which a part of the composition of the group III element and the group V element is substituted with B, Tl; P, As, Sb, Bi.

  A technique for depositing gallium nitride (GaN) by bringing nitrogen or ammonia into contact with a melt (mixed flux) of gallium (Ga) and sodium (Na) under pressure has been developed. At this time, if a seed crystal or a substrate is placed in the mixed flux, gallium nitride (GaN) is deposited on the surface of the seed crystal or the substrate surface. By this technique, a gallium nitride (GaN) single crystal having a thickness of several mm is obtained.

As a material to be placed in the mixed flux, a technology for growing a gallium nitride (GaN) single crystal on the surface of a substrate made of a material different from that of a group III nitride compound semiconductor (a heterogeneous substrate) or a heterogeneous substrate is used. A technique has been reported in which a gallium nitride (GaN) film is epitaxially grown as a template and a gallium nitride (GaN) single crystal is grown on the gallium nitride (GaN) film. However, since the dissimilar substrate has a lattice constant and expansion coefficient different from those of Group III nitride compound semiconductors, cracks occur in the single crystal obtained when the temperature is lowered to room temperature after growth in a flux at high temperature and pressure. Is likely to occur. In addition, in a template in which a gallium nitride (GaN) film or the like is formed on a different substrate, the temperature is lowered from high temperature epitaxial growth to room temperature when the template is created, and the template is placed in a high temperature and high pressure flux. Since the temperature is lowered to room temperature after the growth, the possibility of cracks is further increased. Considering this point, it is preferable to use a self-supporting substrate having the same composition as that of the group III nitride compound semiconductor to be obtained.
JP 2005-187317 A JP 2005-194146 A

  When a so-called self-supporting GaN substrate having a c-plane as a main surface is used as a seed crystal, the crystals adhere to both the front and back gallium (Ga) plane and the nitrogen (N) plane. Among these, a single crystal grows on the Ga surface, but it tends to grow three-dimensionally on the N surface, and it is difficult to grow the crystal smoothly. That is, the GaN single crystal grown on the N-face is difficult to be a commercial product because of its poor quality, so it can be said that the raw material is wasted.

  Therefore, the present inventors, when manufacturing a group III nitride compound semiconductor by the flux method, when using a free-standing substrate made of a group III nitride compound semiconductor in order to avoid the occurrence of cracks in the resulting single crystal. The present invention has been completed for the purpose of suppressing growth on the nitrogen surface and suppressing waste of raw materials due to growth on the nitrogen surface.

  The invention according to claim 1 is a group III by reacting a group III element of gallium (Ga), aluminum (Al) or indium (In) with nitrogen (N) in a mixed flux having an alkali metal. In a method for producing a semiconductor crystal in which a nitride compound semiconductor is grown, a plate-like free-standing substrate made of a group III nitride compound semiconductor and having a + c plane as a main surface is used as a seed crystal, and two plate-like seed crystals are used. As a set of sheets, the nitrogen surfaces of each other are brought into close contact with each other and arranged in the mixed flux so that the normal direction of the + c surface of the seed crystal falls within a range of ± 30 degrees with respect to the horizontal direction. Crystal growth on the group III element side of the seed crystal so that the mixed flux is brought into contact with the group III element surface of the plate-like seed crystal and the mixed flux is not substantially brought into contact with the nitrogen surface. Characteristic II This is a method for producing a group I nitride compound semiconductor crystal. Here, as is well known, the group III nitride compound semiconductor crystal substrate having the + c plane as the main surface has a group III element surface and a nitrogen surface on the front and back. In addition, “does not substantially contact the mixed flux with the nitrogen surface” means that convection of the mixed flux that causes continuous precipitation of crystals does not occur, and does not necessarily completely block the inflow. Not to do.

In the invention according to claim 2, the seed crystal is supported so that the normal direction of the + c plane of the seed crystal is a horizontal direction. It is exposed to the mixed flux.
In addition to the above invention, the following configuration is also described in this specification.
The nitrogen surface of the plate-like seed crystal may be placed in close contact with the mixed flux container wall. Here, “adhesion” means “adhesion” to such an extent that convection of the mixed flux does not occur so that precipitation of crystals occurs continuously, and means that the flow is not completely blocked, for example, “adhesion”. Not a translation. The same applies to the following.
Further, the nitrogen surface of the plate-like seed crystal may be covered with a member made of another material and then placed in the mixed flux container. The term “covering” here refers to the extent to which convection of the mixed flux that causes crystal precipitation continuously occurs, and does not necessarily mean “covering” that completely blocks the inflow. . Further, the size of the member made of another material may be larger than the size of the plate-like seed crystal. In addition, the member made of another material may be a member in which the group III nitride compound semiconductor does not grow on the surface in contact with the mixed flux.

  In order to prevent cracks from occurring in the single crystal obtained by crystal growth by flux, it is preferable to use a free-standing substrate made of a group III nitride compound semiconductor having the same composition as the single crystal to be obtained. However, for example, on a group III nitride compound semiconductor free-standing substrate having a + c plane as a main surface, a single crystal grows on the group III element surface by the flux method, but the crystal easily grows three-dimensionally on the nitrogen surface. It is difficult to grow crystals smoothly. Therefore, waste of raw materials can be suppressed by using a means for blocking the nitrogen surface. Thereby, the amount of single crystal growth increases and a raw material can be used efficiently. It is desirable that the normal direction of the crystal growth surface is a substantially horizontal direction. Thereby, even if the group III nitride compound semiconductor dissolved in the mixed flux becomes supersaturated and miscellaneous crystals are precipitated, the possibility of adhering to the seed substrate from which a single crystal is to be obtained is reduced. In addition, when the nitrogen surface of the plate-like seed crystal is covered with a member made of another material, the inventors make the size of the other member larger than the size of the plate-like seed crystal. Thus, it has been found that the crystal grown from the side surface of the seed crystal can be prevented from entering the nitrogen surface.

Since the crystal growth surface of the plate-like seed crystal is arranged in the vertical or oblique direction, the accommodation efficiency of the seed crystal in the crucible is effectively improved. Further, according to this arrangement method, since the heat convection of the flux in the crucible flows along each crystal growth surface, the flux is sufficiently and evenly supplied to each part of each crystal growth surface.
Therefore, according to the present invention, the crystal growth rate can be improved, and the crystallinity and uniformity of the semiconductor crystal can be improved more effectively than before.
Therefore, according to the present invention, the quality, yield, and production efficiency of the semiconductor crystal can be significantly improved as compared with the conventional case.

  FIG. 1 shows a specific example of the present invention, in which four mixed flux containers (crucibles) 26-1 to 26-4 and a group III nitride compound semiconductor free-standing substrate (seed crystal) 10 having a c-plane as a main surface are arranged. It is a conceptual sectional view showing an example. In the following, for simplicity of description, a GaN free-standing substrate having a c-plane as a main surface as a free-standing substrate (seed crystal) 10, a mixed flux in which gallium and sodium are melted as a mixed flux, and nitrogen gas as a nitrogen source are used. In the present invention, the present invention uses a group III nitride compound semiconductor free-standing substrate 10 having a c-plane of an arbitrary composition as a main surface, and a mixed flux in which a desired group III element and a desired metal are melted as a mixed flux Can be applied to the crystal growth of a group III nitride compound semiconductor by flux using any nitrogen compound or nitrogen plasma as a nitrogen source. In addition, the shape of the mixed flux container (crucible), the shape of the jig, and the like may be a crucible or jig having any known shape with reference to the following.

The first example is shown in FIG. As shown in A, a crucible 26-1 having a planar inner wall facing diagonally upward is prepared, and the nitrogen surface of the GaN free-standing substrate 10 whose principal surface is the c-plane is brought into close contact with the planar inner wall, and the gallium surface F _Ga is exposed. The GaN free-standing substrate 10 is supported by the bottom of the crucible 26-1 and the planar inner wall facing obliquely upward using a fastener (not shown), and does not move. Thus, FIG. A mixed flux in which gallium and sodium are melted up to the position indicated by the long broken line A is placed under pressurized nitrogen, and a GaN single crystal is formed on the gallium surface F _Ga of the GaN free-standing substrate 10 whose principal surface is the c-plane. Precipitate and grow single crystal.

A second example is shown in FIG. As shown in B, a crucible 26-2 having a planar inner wall facing in the horizontal direction is prepared, and the nitrogen surface of the GaN free-standing substrate 10 whose principal surface is the c-plane is adhered to the planar inner wall, and the gallium surface F _Ga is exposed. At this time, using the jig ST-2, the GaN free-standing substrate 10 is fixed so as not to be separated from the planar inner wall of the crucible 26-2. Thus, FIG. Filled with a mixed flux in which gallium and sodium are melted up to the position indicated by the long broken line in B, and placed under pressurized nitrogen, a GaN single crystal is formed on the gallium surface F _Ga of the GaN free-standing substrate 10 having the c-plane as the main surface. Precipitate and grow single crystal.

A third example is shown in FIG. Like C, the crucible 26-3 has a flat bottom, and the shape is arbitrary, for example, a cylindrical shape. A jig ST-3 is arranged on the flat bottom, and two pieces are placed on the jig ST-3. GaN free-standing substrates 10-1 and 10-2 having a c-plane as a main surface are disposed. Here, the GaN free-standing substrates 10-1 and 10-2 having the two c-planes as the main surfaces are attached to the jig ST-3 so that their nitrogen surfaces are in close contact and the c-axis is in the horizontal direction. Fixed. That is, the GaN free-standing substrates 10-1 and 10-2 each having the two c-planes as the main surfaces are in a state in which the gallium surfaces _FGa- 1 and _FGa- 2 are exposed. Thus, FIG. Each gallium of the GaN free-standing substrates 10-1 and 10-2 having a mixed flux in which gallium and sodium are melted up to a position indicated by a long broken line C and placed under pressurized nitrogen and having a c-plane as a main surface A GaN single crystal is deposited on the planes F _Ga −1 and F _Ga −2 to grow a single crystal.

A fourth example is shown in FIG. Like D, the crucible 26-4 has a flat bottom, and the shape is arbitrary, for example, a cylindrical shape. A jig ST-4 is arranged on the flat bottom, and the c-plane is placed on the jig ST-4. The GaN free-standing substrate 10 having a main surface of is fixed. Here, the GaN free-standing substrate 10 having the c-plane as a main surface is fixed to the jig ST-4 so that the nitrogen surface is covered with the jig ST-4 and the c-axis is in the horizontal direction. That is, the GaN free-standing substrate 10 having the c-plane as the main surface is in a state where the gallium surface F _Ga is exposed. Thus, the crucible 26-4, FIG. Filled with a mixed flux in which gallium and sodium are melted up to the position indicated by the long broken line in D, and placed under pressurized nitrogen, a GaN single crystal is formed on the gallium surface F _Ga of the GaN free-standing substrate 10 having the c-plane as the main surface. Precipitate and grow single crystal. Here, the size of the jig ST-4 is preferably slightly larger than the size of the GaN free-standing substrate 10. By being slightly larger, there is less possibility that the crystal grown on the side surface will wrap around the nitrogen surface of the GaN free-standing substrate 10. If it is too large, the possibility of inhibiting the convection of the solution increases.

Other conditions for carrying out the present invention will be described.
The reaction temperature between the group III element and nitrogen in the flux is more preferably 500 ° C. or more and 1100 ° C. or less, and more preferably about 850 ° C. to 900 ° C. The atmospheric pressure of the nitrogen-containing gas is preferably 0.1 MPa or more and 6 MPa or less, and more preferably about 3.5 MPa to 4.5 MPa. Further, when ammonia gas (NH ₃ ) is used, the atmospheric pressure may be reduced. The nitrogen gas used may be in a plasma state.

Further, as an impurity added to a desired group III nitride compound semiconductor crystal, boron (B), thallium (Tl), calcium (Ca), a compound containing calcium (Ca), silicon, and the like in the mixed flux (Si), sulfur (S), selenium (Se), tellurium (Te), carbon (C), oxygen (O), aluminum (Al), indium (In), alumina (Al ₂ O ₃ ), indium nitride ( InN), silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), indium oxide (In ₂ O ₃ ), zinc (Zn), magnesium (Mg), strontium (Sr), barium (Ba), zinc oxide (ZnO), magnesium oxide (MgO), germanium (Ge), or the like may be included. These impurities may contain only one type, may contain a plurality of types at the same time, or may not necessarily contain them. That is, these selections and combinations may be arbitrary. By adding these impurities, the band gap, electrical conductivity, lattice constant, preferential growth orientation, and the like of the target semiconductor crystal can be adjusted to desired characteristic values.

Also, before the start of the target crystal growth based on the flux method, the seed crystal (group III nitride compound semiconductor crystal) that is a part of the base substrate is eased or prevented from melting in the flux. Therefore, for example, nitrides such as Ca ₃ N ₂ , Li ₃ N, NaN ₃ , BN, Si ₃ N ₄ , and InN may be included in the flux in advance. By containing these nitrides in the flux, the concentration of nitrogen in the flux increases, so the melting of the seed crystal into the flux before the start of the desired crystal growth is prevented or alleviated. It becomes possible.

Moreover, as a crystal growth apparatus to be used, any apparatus can be used as long as the flux method can be performed. For example, the apparatus described in the above-mentioned patent document can be applied or applied. However, it is desirable that the temperature of the reaction chamber of the crystal growth apparatus when performing crystal growth according to the flux method can be arbitrarily controlled to rise and fall to about 1000 ° C. Further, it is desirable that the pressure in the reaction chamber can be arbitrarily controlled to increase or decrease to about 100 atm (about 1.0 × 10 ⁷ Pa). In addition, the electric furnace, stainless steel container (reaction container), raw material gas tank, and piping of these crystal growth apparatuses are made of a material having high heat resistance and high pressure resistance such as stainless steel (SUS) material or alumina material. It is desirable to form.
For the same reason, the crucible is required to have high heat resistance and alkali resistance. For example, it is desirable to form from metal such as tantalum (Ta), tungsten (W), molybdenum (Mo), alumina, sapphire, or pyrolytic boron nitride (PBN), ceramics, or the like.

  Further, as a crystal growth apparatus to be used, an apparatus having means for swinging a flux and a seed crystal may be used. Such a rocking means provides an agitation action on the flux, so that the flux may be supplied more uniformly on the crystal growth surface. Further, the number of swings depends on the swing angle, but for example, about 10 times / minute is sufficient.

The size and thickness of the seed crystal may be arbitrary, but considering industrial practicality, a circular shape with a diameter of about 45 mm, a square with about 27 mm square, a square with about 13 mm square, etc. are more desirable. Further, the larger the radius of curvature of the crystal growth surface of the seed crystal, that is, the flatter the surface, the better.
The direction of the normal line of the seed substrate is preferably closer to the horizontal. Further, when the crucible is swung, the effect is high if the average direction of the normal line of the crystal growth surface is maintained at a right angle or a direction close to the right angle with respect to the swing direction.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

First, a GaN free-standing substrate 10 having a diameter of 50 mm and a thickness of 0.5 mm was prepared. The GaN free-standing substrate 10 may be dissolved into the flux until the desired semiconductor crystal is grown by the flux method. In this case, a self-supporting substrate having a thickness that does not disappear is required.
In addition, as another method for preventing or mitigating such disappearance (dissolution of seed crystals), for example, in the crystal growth treatment described later, before the implementation, Ca ₃ N ₂ , Li ₃ N is contained in the mixed flux. , NaN ₃ , BN, Si ₃ N ₄ or InN may be added in advance.

FIG. 2 shows the configuration of the crystal growth apparatus 20 used in this embodiment. This crystal growth apparatus 20 is for performing crystal growth processing based on the flux method, and is provided with a supply pipe 21 for supplying high-temperature and high-pressure nitrogen gas (N ₂ ), and exhausting the nitrogen gas. In an electric furnace (external container) 25 having an exhaust pipe 22, a heater H, a heat insulating material 23, and a stainless steel container (internal container) 24 are provided. The electric furnace (external container) 25, the air supply pipe 21, the exhaust pipe 22, and the like are made of a stainless steel (SUS) or alumina material in consideration of heat resistance, pressure resistance, reactivity, and the like.

A crucible 26 (reaction container) is set in the stainless steel container 24. The crucible 26 can be formed from, for example, tungsten (W), molybdenum (Mo), boron nitride (BN), pyrolytic boron nitride (PBN), or alumina (Al ₂ O ₃ ). .
The temperature in the electric furnace 25 can be arbitrarily controlled to rise and fall within a range of 1000 ° C. or less. Further, the pressure of the crystal atmosphere in the stainless steel container 24 can be arbitrarily controlled within the range of 1.0 × 10 ⁷ Pa or less.
Although not shown in FIG. 2, the above-described GaN free-standing substrate 10 has the structure shown in FIG. Using the jig ST-4 of D, the gallium surface _FGa was exposed and placed in the crucible 26 (reaction vessel). Here, the size of the jig ST-4 was made larger by about 2.5 mm than the GaN free-standing substrate 10 used. That is, the diameter of the jig ST-4 was 55 mm.

Hereinafter, the crystal growth process of Example 1 using the crystal growth apparatus will be described.
First, 15 g of sodium (Na) and 20 g of gallium (Ga) are placed in a reaction vessel (crucible 26) in which a GaN free-standing substrate 10 is placed, and the reaction vessel (crucible 26) is placed in a reaction chamber (crystal growth apparatus). After being placed in the stainless steel container 24), the gas in the reaction chamber is exhausted.
However, when these operations are performed in the air, Na is immediately oxidized. Therefore, the operation of setting the substrate and raw materials in the reaction vessel is performed in a glove box filled with an inert gas such as Ar gas. . In addition, if necessary, any of the above-mentioned additives such as alkaline earth metals may be introduced into the crucible in advance.

Next, while adjusting the temperature of the crucible to about 880 ° C., in parallel with the temperature adjustment step, nitrogen gas (N ₂ ) is newly fed into the reaction chamber of the crystal growth apparatus, and this reaction is thereby performed. The gas pressure of nitrogen gas (N ₂ ) in the chamber is maintained at about 3.7 MPa. At this time, the GaN free-standing substrate 10 was immersed in the melt (mixed flux) generated as a result of the temperature rise and held in the crucible 26.

At this time, it is desirable that the gallium surface F _Ga which is the crystal growth surface is always immersed in the mixed flux, and the melt is a nitrogen component in the atmosphere by heat convection based on the heating action of the heater H. It is desirable that (N ₂ or N) is always sufficiently taken in. The growth rate of the desired semiconductor crystal can be improved by the thermal convection of the mixed flux.

  Thereafter, thermal convection of the mixed flux was continuously generated, and while the mixed flux was stirred and mixed, the crystal growth condition of (2) was maintained for about 200 hours to continue the crystal growth.

By setting the conditions as described above, the vicinity of the crystal growth surface of the seed crystal is continuously supersaturated with the material atoms (Ga and N) of the group III nitride compound semiconductor, so that the desired semiconductor crystal (GaN single crystal) ) On the gallium surface F _Ga which is the crystal growth surface of the GaN free-standing substrate 10.

Next, after the temperature of the reaction chamber of the crystal growth apparatus is lowered to near room temperature, the grown GaN single crystal (desired semiconductor crystal) is taken out, and its periphery is also maintained at 30 ° C. or less to surround the GaN single crystal. The flux (Na) adhering to is removed with ethanol.
By sequentially executing the above steps, a high-quality semiconductor single crystal (grown GaN single crystal) can be manufactured at a low cost. This semiconductor single crystal has substantially the same area as the seed crystal GaN free-standing substrate 10 and has a thickness in the c-axis direction of about 2 mm, and has significantly fewer cracks than in the past (FIG. 3.A).

  Crystal growth was performed in the same manner as in Example 1, but the size of the jig ST-4 was the same as the size of the GaN free-standing substrate 10 as a seed crystal. The material was sapphire. When the crystals grown from the flux were recovered by cooling to room temperature, FIG. As shown in B, the crystal grown from the side surface of the GaN free-standing substrate 10 wraps around the nitrogen surface of the seed crystal on the bonding surface side between the GaN free-standing substrate 10 and the jig ST-4. The wraparound crystal bites into the jig ST-4, and a crack 30 is generated in a part of the grown crystal. From this, it can be seen that the size of the jig ST-4 is preferably larger than the size of the GaN free-standing substrate 10 which is a seed crystal.

[Modification of the above embodiment]
The embodiment of the present invention is not limited to the above-described embodiment, and other modifications as exemplified below may be made. Even with such modifications and applications, the effects of the present invention can be obtained based on the functions of the present invention.
For example, in the composition formula of a group III nitride compound semiconductor constituting a desired semiconductor crystal, at least a part of group III elements (Al, Ga, In) is made of boron (B) or thallium (Tl). Alternatively, at least part of nitrogen (N) can be replaced with phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), or the like.

  In addition, as the p-type impurity (acceptor), for example, an alkaline earth metal (eg, magnesium (Mg), calcium (Ca), or the like) can be added. As the n-type impurity (donor), for example, an n-type impurity such as silicon (Si), sulfur (S), selenium (Se), tellurium (Te), or germanium (Ge) may be added. it can. Moreover, two or more elements may be added simultaneously to these impurities (acceptor or donor), or both types (p-type and n-type) may be added simultaneously. That is, these impurities can be added to a desired semiconductor crystal, for example, by being previously melted in a flux.

  The present invention is useful for manufacturing a semiconductor device using a semiconductor crystal made of a Group III nitride compound semiconductor. Moreover, as these semiconductor devices, other general semiconductor devices, such as FET, can be mentioned besides light emitting elements, such as LED and LD, a light receiving element, etc., for example.

4 conceptual cross-sectional views showing a method for arranging a group III nitride compound semiconductor free-standing substrate (seed crystal) 10 having a main surface of the shape and c-plane of mixed flux containers (crucibles) 26-1 to 26-4 of the present invention. . The block diagram of the crystal growth apparatus 20 used in the Example. Explanatory drawing which showed the crystal | crystallization obtained by the manufacturing method of the Example.

10, 10-1, 10-2: Free-standing substrate made of a group III nitride compound semiconductor having a c-plane as a main surface F _Ga : Gallium surface of c-plane 23: Insulating material H: Heater (heating device)
24: Stainless steel container (inner container)
25: Electric furnace (outer container)
26, 26-1, 26-2, 26-3, 26-4: Mixed flux container (crucible)
ST-2, ST-3, ST-4: Jig for supporting a self-supporting substrate

Claims (2)

Crystal growth of group III nitride compound semiconductors by reacting group III elements of gallium (Ga), aluminum (Al) or indium (In) with nitrogen (N) in a mixed flux containing alkali metals In the manufacturing method of the semiconductor crystal to be made,
A plate-like self-supporting substrate made of a group III nitride compound semiconductor and having a + c plane as a main surface is used as a seed crystal, two plate-like seed crystals are used as one set, and the nitrogen surfaces of the two plates are brought into close contact with each other. It is arranged in the mixed flux so that the normal direction of the + c plane of the seed crystal falls within a range of ± 30 degrees with respect to the horizontal direction,
The mixed flux is brought into contact with the group III element surface of the plate-like seed crystal having the + c plane as a main surface, and the mixed flux is not substantially brought into contact with the nitrogen surface, so that the group III of the seed crystal A method for producing a group III nitride compound semiconductor crystal, comprising crystal growth on the element surface side.   The seed crystal is supported so that the normal direction of the + c plane of the seed crystal is a horizontal direction, and both gallium surfaces of the seed crystal in one set are exposed to the mixed flux. The method for producing a group III nitride compound semiconductor crystal according to claim 1, wherein:

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