JP2016069267A - Manufacturing method and manufacturing device of group iii nitride crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing device of a group III nitride crystal having productivity improved by suppressing thermal decomposition of a nitrogen element-containing gas.SOLUTION: A manufacturing device of a group III nitride crystal includes a chamber, a nitrogen element-containing gas inlet tube for introducing a nitrogen element-containing gas into the chamber, a holder for holding a group III oxide, a first heater for heating the holder, a reductive gas inlet tube for supplying a reductive gas to the group III oxide, a reduced substance gas supply port for supplying a reduced substance gas of the group III oxide reduced by the reductive gas to the chamber, an exhaust port for discharging the reduced substance gas of the group III oxide and the nitrogen element-containing gas to the outside of the chamber, and a second heater for heating a seed substrate in the chamber. The distance between the holder and the first heater is shorter than the distance between the nitrogen element-containing gas inlet tube and the first heater.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a method and an apparatus for manufacturing a group III nitride crystal.

  Group III nitride crystals are used in heterojunction high-speed electronic devices such as power semiconductors, and optoelectronic devices such as LEDs and lasers. As a method for producing a group III nitride crystal, an oxide vapor phase growth method using a group III oxide as a raw material has been devised (for example, see Patent Document 1).

The reaction system in this oxide vapor phase growth method is as follows. Ga ₂ O ₃ is heated, and hydrogen gas is introduced in this state. The introduced hydrogen gas (H ₂ ) reacts with Ga ₂ O ₃ to generate Ga ₂ O gas (the following formula (I)). Then, ammonia gas is introduced and reacted with the generated Ga 2 _O gas, on a seed substrate, to produce a GaN crystal (the following formula (II)).
Ga ₂ O ₃ + 2H ₂ → Ga ₂ O + 2H ₂ O (I)
Ga ₂ O + 2NH ₃ → 2GaN + H ₂ O + 2H ₂ (II)

JP 2009-234800 A

  However, conventionally, a nitrogen-containing gas such as ammonia gas may be thermally decomposed during the introduction process. Then, in the reaction formula (II), there is a problem that ammonia, which is a nitrogen element-containing gas, is deficient due to thermal decomposition, the amount of GaN that is a group III nitride crystal is reduced, and productivity is lowered.

  Therefore, an object of the present disclosure is to provide a method and an apparatus for manufacturing a group III nitride crystal that can improve productivity.

In order to achieve the above object, a group III nitride crystal production apparatus according to the present disclosure includes:
A chamber;
A nitrogen element-containing gas introduction pipe for introducing a nitrogen element-containing gas into the chamber;
A holding part for holding a Group III element oxide or metal;
A first heater for heating the holding unit;
A reactive gas introduction pipe for supplying a reactive gas to the oxide or metal of the group III element;
A compound gas supply port for supplying the compound gas of the group III element reacted by the reactive gas into the chamber;
An exhaust port for discharging the compound gas and the nitrogen element-containing gas out of the chamber;
A second heater for heating the seed substrate in the chamber;
With
The distance between the holding portion and the first heater is closer than the distance between the nitrogen element-containing gas introduction pipe and the first heater.

In addition, in the present disclosure, a method for producing a group III nitride crystal includes:
A step of reacting a Group III element oxide or metal in a heated atmosphere to generate a Group III element compound gas;
Mixing the nitrogen-containing gas at a lower temperature than the compound gas and the compound gas;
Reacting the mixed nitrogen-containing gas and the compound gas to produce a group III nitride crystal.

  As described above, the group III nitride crystal manufacturing apparatus and method according to the present disclosure suppresses the amount of thermal decomposition by lowering the gas temperature, and does not cause a shortage of nitrogen element-containing gas in the gas mixing region upstream of the seed substrate. As a result, the productivity of the group III nitride crystal can be improved.

1 is a diagram illustrating an example of a configuration of a group III nitride crystal manufacturing apparatus according to Embodiment 1. FIG. FIG. 3 is a plan perspective view of the group III nitride crystal production apparatus of FIG. It is a figure which shows an example of a structure of the group III nitride crystal manufacturing apparatus which concerns on the modification 1. FIG. It is a figure which shows an example of a structure of the group III nitride crystal manufacturing apparatus which concerns on the modification 2. FIG. It is a figure which shows an example of a structure of the group III nitride crystal manufacturing apparatus which concerns on the modification 3. FIG.

A group III nitride crystal manufacturing apparatus according to the first aspect of the present disclosure includes: a chamber;
A nitrogen element-containing gas introduction pipe for introducing a nitrogen element-containing gas into the chamber;
A holding part for holding a Group III element oxide or metal;
A first heater for heating the holding unit;
A reactive gas introduction pipe for supplying a reactive gas to the oxide or metal of the group III element;
A compound gas supply port for supplying the compound gas of the group III element reacted by the reactive gas into the chamber;
An exhaust port for discharging the compound gas and the nitrogen element-containing gas out of the chamber;
A second heater for heating the seed substrate in the chamber;
With
The distance between the holding portion and the first heater is closer than the distance between the nitrogen element-containing gas introduction pipe and the first heater.

  In the group III nitride crystal production apparatus according to the second aspect, in the first aspect, the nitrogen element-containing gas introduction pipe may be covered with a heat insulating material.

  The group III nitride crystal production apparatus according to the third aspect may further comprise an inert gas introduction pipe between the nitrogen element-containing gas introduction pipe and the holding part in the first or second aspect. Good.

A Group III nitride crystal production method according to a fourth aspect includes a step of reacting a Group III element oxide or metal in a heated atmosphere to generate a Group III element compound gas;
Mixing the nitrogen element-containing gas at a temperature lower than that of the compound gas and the reduced gas of the group III oxide;
Reacting the mixed nitrogen-containing gas and the reduced gas of the group III oxide to produce a group III nitride crystal;
Have

  The group III nitride crystal production method according to a fifth aspect is the fourth aspect, wherein the compound gas and the compound gas are produced by an inert gas at a temperature lower than the compound gas and higher than the nitrogen element-containing gas. The step of mixing may be performed after transferring the nitrogen-containing gas.

  In the Group III nitride crystal production method according to a sixth aspect, in the fourth or fifth aspect, a temperature difference between the compound gas and the nitrogen element-containing gas may be 150 ° C. or less.

In the Group III nitride crystal manufacturing method according to a seventh aspect, in any one of the fourth to sixth aspects, the compound gas may be Ga ₂ O and the nitrogen element-containing gas may be ammonia.

  The group III nitride crystal production method according to an eighth aspect is the method according to any one of the fourth to sixth aspects, wherein the compound gas is generated by reacting a metal of the group III element and an oxidizing agent. Also good.

  Hereinafter, a group III nitride crystal manufacturing apparatus and a group III nitride crystal manufacturing method according to embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
1 is a diagram showing an example of the configuration of a group III nitride crystal production apparatus according to Embodiment 1. FIG. In FIG. 1, the size, ratio, and the like of each constituent member may be different from actual ones. The group III nitride crystal manufacturing apparatus according to the first embodiment includes a chamber 101, a nitrogen element-containing gas introduction pipe 100 for introducing a nitrogen element-containing gas into the chamber 101, and a group III oxide. Group III oxide raw material placing part 105 as a holding part, raw material heating means 104 as a first heater for heating group III oxide raw material placing part 105, and reduction for supplying a reducing gas to the group III oxide A reductant gas supply pipe 111, a quartz tube 115 functioning as a reductant gas supply port for supplying the reduced gas of the group III oxide reduced by the reducing gas into the chamber 101, and a reduced group III oxide An exhaust port 108 that functions as an exhaust port for exhausting the gas and the nitrogen-containing gas to the outside of the chamber 101, and a second heater that heats the seed substrate 102 in the chamber 101. It comprises a plate heater 112.

  In this group III nitride crystal manufacturing apparatus, the group III oxide raw material placing part 105 is located between the nitrogen element-containing gas introduction pipe 100 and the raw material heating means 104. Since the nitrogen element-containing gas introduction pipe 100 is disposed at a position separated from the raw material heating means 104, excessive heating of the nitrogen element-containing gas introduction pipe 100 can be suppressed. Thereby, the amount of thermal decomposition can be suppressed by lowering the gas temperature of the nitrogen element-containing gas, and a shortage of nitrogen element-containing gas can be prevented in the gas mixing region upstream of the seed substrate 102. As a result, the productivity of the group III nitride crystal can be improved.

Details of the group III nitride crystal production apparatus will be described below.
In this group III nitride crystal manufacturing apparatus, a quartz tube 115 that functions as a reduced gas supply port for a group III oxide is disposed in a chamber 101. The right side of the quartz tube 115 is fixed to the chamber 101, and reducing gas is introduced from the reducing gas introduction tube 111. The quartz tube 115 has a group III oxide raw material placing portion 105 inside.

<Chamber>
Examples of the shape of the chamber 101 include a cylindrical shape, a quadrangular prism shape, a triangular prism shape, and a combination thereof. Examples of the material forming the chamber 101 include quartz, alumina, aluminum titanate, mullite, tungsten, and molybdenum.
In the present embodiment, the shape of the chamber 101 is a quadrangular prism and the material is quartz.
In the chamber 101, a seed substrate 102 is placed on a substrate holder 109 (stage). The substrate holder 109 may be provided with a substrate rotation mechanism. By rotating the seed substrate 102 at a rotational speed of 5 to 100 rpm, the flatness of the growing crystal can be improved. A substrate heater 109 for heating the seed substrate 102 is mounted on the substrate holder 109.

  Examples of the substrate heater 112 include a resistance heater such as a ceramic heater or a carbon heater, a high-frequency heating device, a condenser heater, or the like. Further, the temperature of the substrate heater 112 is controlled by a processor provided on a circuit board provided in the substrate heater 112 or by a separate device. Note that a program is stored in the processor or device, and predetermined processing is executed by the program.

<Group III oxide raw material>
In addition, as a Group III oxide raw material, a material having a purity of 4N (99.99%) or more is used, and the shape is not particularly specified, but a shape having a wide contact area with a reducing gas that passes therethrough to promote the reaction is used. preferable. Here, Ga ₂ O ₃ is used as a group III oxide raw material.

<Reducing gas>
Examples of the reducing gas that can be used include hydrocarbon gases such as hydrogen gas, carbon monoxide gas, methane gas, and ethane gas, hydrogen sulfide gas, and sulfur dioxide gas. Among these, it is preferable to employ hydrogen gas. The gas is preferably heated and supplied into the quartz tube 115, but it may be at room temperature. The gas flow rate may be changed according to the size of the seed substrate 102. Further, the raw material heating means 104 is provided at the lower part of the quartz tube 115, and the reaction of the following reaction formula (III) same as the above reaction formula (I) occurs in the quartz tube 115.
Ga ₂ O ₃ + 2H ₂ → Ga ₂ O + 2H ₂ O (III)
This reaction requires heating at 800 ° C. or higher, and 900 ° C. or higher is desirable in order to produce more reduction gas Ga ₂ O (g).

<Raw material heating means>
The raw material heating means 104 heats the group III oxide raw material in the quartz tube 115 and the reducing gas introduced from the reducing gas introduction tube 111, and at the same time, the nitrogen element-containing gas introduction tube 100 disposed above the quartz tube 115. Also heat. However, since the nitrogen element-containing gas introduction tube 100 is disposed at a position away from the raw material heating means 104, the nitrogen element-containing gas heated in the nitrogen element-containing gas introduction tube 100 was heated in the quartz tube 115. The temperature is lower than that of reducing gas.

  Examples of the raw material heating means 104 include a ceramic heater, a high frequency heating device, a resistance heater, a condenser heater, and the like. Moreover, the temperature of the raw material heating means 104 is controlled by a processor provided on a circuit board provided in the raw material heating means 104 or by a separate device.

<Nitrogen-containing gas>
As the nitrogen element-containing gas, for example, ammonia gas, hydrazine gas, or the like can be used. Both ammonia and hydrazine gas decompose at high temperatures to produce hydrogen and nitrogen. Among these, ammonia gas is particularly preferable in view of safety, production cost, and the like.

The reduced gas of group III oxide supplied from the quartz tube 115 and the nitrogen element-containing gas supplied from the nitrogen element-containing gas introduction tube 100 are mixed in the chamber 101 and pass through the main surface of the seed substrate 102. To the exhaust port 108 located at the left end of the chamber 101. The reaction of the following reaction formula (IV) same as the above reaction formula (II) is performed by the mixed gas.
Ga ₂ O + 2NH ₃ → 2GaN + H ₂ O + 2H ₂ (IV)

<Mechanism in this aspect>
In the above apparatus structure, the group III oxide raw material placing part 105 is located between the nitrogen element-containing gas introduction pipe 100 and the raw material heating means 104. That is, the distance between the group III oxide raw material placing part 105 and the raw material heating means 104 is closer than the distance between the nitrogen element-containing gas introduction pipe 100 and the raw material heating means 104. This suppresses the amount of thermal decomposition so that a shortage of nitrogen element-containing gas does not occur in the gas mixing region upstream of the seed substrate 102, and increases the amount of GaN that is a group III nitride crystal on the seed substrate 102. , Productivity can be improved. This mechanism will be described below.

  The amount of crystals (subsaturation amount) that can exist as gas at a certain temperature is determined for crystals that undergo sublimation reaction. Solidify on the member). At this time, what can be solidified as a single crystal is on the seed substrate. In the case of a compound crystal such as a group III nitride, it is necessary to mix a group III oxide reduced gas and a nitrogen element-containing gas. Therefore, in order to increase the growth rate in order to improve the productivity of compound crystals such as group III nitrides, it is necessary to increase both the reductant gas and the nitrogen element-containing gas. In order to increase the reduced gas, it is necessary to increase the temperature of the Group III oxide raw material and the reducing gas and increase the saturation concentration.

  However, when the temperature of the ammonia gas, which is a nitrogen element-containing gas, is increased, thermal decomposition starts at 800 ° C. or higher, and at 1200 ° C., the thermal decomposition rate is about 90%, and ammonia gas that is effective for the generation of group III nitrides. There is a problem of a significant decrease.

  Therefore, in order to increase the amount of ammonia, which is a nitrogen element-containing gas, it is necessary to suppress the amount of thermal decomposition by lowering the temperature of ammonia. Accordingly, in the present embodiment, the present inventors do not provide a heating means on the ceiling side of the chamber 101 and are located above the quartz tube 115, that is, at a position away from the raw material heating means 104. The structure of arranging the nitrogen element-containing gas introduction pipe 100 was obtained. Thereby, the temperature rise of the nitrogen element-containing gas supplied from the nitrogen element-containing gas introduction pipe 100 can be suppressed, and as a result, suppression of thermal decomposition can be achieved. Here, the quartz tube 115 for supplying the reduced gas onto the raw material heating means 104 is structured so that the nitrogen element-containing gas introduction tube 100 is laminated thereon. As a result, the nitrogen element-containing gas temperature can be made lower than the reductate gas temperature, and the amount of decomposition of ammonia, which is a nitrogen element-containing gas, can be suppressed as much as possible. It becomes possible to improve the property.

  By the way, when the ammonia gas temperature is set to about room temperature in order to suppress the amount of thermal decomposition, the gas in the gas mixing region and the substrate region is uniform due to convection due to the temperature difference with the reductant gas heated to 900 ° C. or higher. Thus, the film thickness cannot be maintained, the film thickness uniformity such as the growth rate is lowered, and the productivity is lowered. In the present apparatus, the mixing point is located at the tip of the quartz tube 115. At this tip, the reducing gas of the group III oxide and the nitrogen element-containing gas meet and are mixed. The group III oxide reducing gas is generated by heating the group III oxide and the reducing gas at a high temperature. The reaction proceeds as the temperature rises, and the amount of group III oxide reducing gas supply increases and becomes saturated. It is in a state. Therefore, since supercooling near the reductant gas outlet leads to reprecipitation of the reductant gas, caution is also required for cooling near the reductant gas outlet by the nitrogen-containing gas whose temperature has been excessively lowered. . In contrast, in the present embodiment, the nitrogen element-containing gas introduction pipe 100 is disposed above the quartz tube 115 so that the nitrogen element-containing gas is heated appropriately and the temperature difference from the reductant gas. To prevent it from becoming too large.

  In the first embodiment, the group III oxide and the reducing gas are heated to 950 ° C. by the raw material heating means 104, and the ammonia gas in the nitrogen element-containing gas introduction pipe thereabove is set at a lower temperature. In the apparatus used by the inventors, the ammonia gas temperature is about 850 ° C., for example. The ammonia gas temperature should be lower than the group III oxide reductate gas temperature, and the temperature difference between the ammonia gas and the group III oxide reductate gas is preferably 150 ° C. or less. When the temperature difference between the two gases is larger than 150 ° C., gas convection occurs between the mixing point of the two gases and the seed substrate, and uniform gas supply cannot be performed. This is because the productivity is lowered and the productivity is lowered. The temperature control is achieved by a processor provided on a circuit board provided in the raw material heating means 104 or by a separate device.

  The linear distance from the mixing point of the nitrogen element-containing gas supplied from the nitrogen element-containing gas introduction tube 100 and the reduced gas of the group III oxide supplied from the quartz tube 115 to the seed substrate 102 is 40 mm or more and 50 mm or less. Is preferably ensured. The inventors have found that an appropriate reaction distance and time can be ensured when the distance from the mixing point of the reduced gas of group III oxide and the nitrogen-containing gas to the seed substrate 102 is 40 mm or more and 50 mm or less. ing. When the reaction path is less than 40 mm, the reaction becomes insufficient, and the reaction intermediate product is deposited on the seed substrate 102 as polycrystalline or amorphous. On the other hand, if the reaction path exceeds 50 mm, the nitrogen element-containing gas diffuses and the concentration in the mixed gas decreases, and a single crystal cannot be grown on the entire surface of the seed substrate 102.

  Here, if the current partial pressure with respect to the partial pressure that can exist as a gas at a certain temperature is defined as the supersaturation degree, in this embodiment, the supersaturation at the temperature of the substrate heater 112 is performed with respect to the supersaturation degree of the mixed gas. The degree x is 1 <x <1.2. By setting the temperature satisfying this range, that is, heating by the substrate heater 112 within the supersaturation range of the mixed gas, high-quality crystals can be grown on the seed substrate 102.

  In this group III nitride manufacturing apparatus, it is preferable to create a gas flow by sucking air from the exhaust port 108. Therefore, the pressure condition in the furnace is, for example, in the range of 9.5 × 10E4 to 9.9 × 10E4Pa. There may be.

  FIG. 2 is a plan perspective view of the group III nitride manufacturing apparatus according to Embodiment 1 of FIG. The seed substrate 102 is heated by the substrate heater 112, and the supply port (tip portion) of the nitrogen element-containing gas introduction tube 100 and the quartz tube 115 for supplying the reducing gas of the group III oxide is positioned upstream of the seed substrate 102. ing. The widths of the nitrogen element-containing gas introduction tube 100, the quartz tube 115, and the exhaust port 108 are equal to or larger than the diameter of the seed substrate 102.

(Modification 1)
FIG. 3 is a diagram illustrating an example of the configuration of the group III nitride crystal manufacturing apparatus according to the first modification. As shown in FIG. 3, the nitrogen element-containing gas introduction pipe 100 may have a shape in which a heat insulating material 113 is disposed between or surrounded by the heat insulating material 113 in order to suppress heating from the raw material heating means 104. With this structure, it is possible to suppress the decomposition amount even a little by suppressing the overheating of the nitrogen element-containing gas.

(Modification 2)
FIG. 4 is a diagram illustrating an example of the configuration of a group III nitride crystal manufacturing apparatus according to the second modification. As shown in FIG. 4, the inert gas introduction pipe 110 may be disposed between the nitrogen element-containing gas introduction pipe 100 and the raw material heating means 104. With this structure, it is possible to suppress the amount of decomposition by suppressing overheating of the nitrogen element-containing gas, and control the mixing region so that the reduced gas and the nitrogen element-containing gas do not merge in the low temperature region. However, the seed substrate 102 can be made to grow optimally. In particular, in the case of a compound crystal such as a group III nitride, a reaction time is required until the group III nitride is formed after the group III oxide reducing gas and the nitrogen element-containing gas are mixed. This is because, when the reducing gas of the group oxide and the nitrogen element-containing gas are combined in a low temperature region, the reaction becomes insufficient and precipitates as polycrystalline or amorphous rather than single crystal. Therefore, by introducing and separating the inert gas, it is possible to suppress polycrystals by moving the mixed region of the reduced product gas and the nitrogen element-containing gas toward the seed substrate 102 that is at a higher temperature. Examples of the inert gas include nitrogen gas, helium gas, and argon gas. Nitrogen gas is optimal in consideration of cost. In this case, an inert gas having a temperature lower than that of the group III oxide reducing gas (compound gas) and higher than the nitrogen element-containing gas is introduced from the inert gas introduction pipe 110. That is, the step of transferring the compound gas and the nitrogen element-containing gas with an inert gas at a temperature lower than that of the compound gas and higher than that of the nitrogen element-containing gas and then mixing them is performed.

(Modification 3)
FIG. 5 is a diagram illustrating an example of the configuration of the group III nitride crystal manufacturing apparatus according to the third modification. As shown in FIG. 5, the nitrogen element-containing gas heating means 114 may be used to stably control the gas temperature in the nitrogen element-containing gas introduction pipe 100 at an optimum temperature. Here, the optimum temperature means that the nitrogen element-containing gas temperature is lower than the group III oxide reduced gas temperature, and the temperature difference between the nitrogen element containing gas and the group III oxide reduced gas will be described later. Thus, the temperature is 150 ° C. or lower. As the gas temperature difference is smaller, the nonuniformity of the gas distribution due to thermal convection in the gas mixing region is suppressed, but the decomposition rate of the nitrogen element-containing gas increases as the nitrogen element-containing gas temperature increases. Thereby, even if the amount of group III oxide raw material and the flow rate of the reducing gas change, the nitrogen element-containing gas temperature does not change, and stable control is possible at a desired temperature. The stable control is achieved by a processor provided on a circuit board provided in the nitrogen element-containing gas heating unit 114 or by a separate device.

  The height from the seed substrate 102, which is the crystal growth space in FIGS. 1 and 3 to 5, to the ceiling of the chamber 101 is preferably in the range of 30 mm to 60 mm. When the height of the crystal growth space is less than 30 mm, the space in which the gas can move is too narrow, so that polycrystallization is promoted. On the other hand, when the height of the crystal growth space exceeds 60 mm, the nitrogen element-containing gas diffuses, and the nitrogen concentration on the seed substrate 102 cannot be maintained. Therefore, the height of the crystal growth space is preferably in the range of 30 mm or more and 60 mm or less.

The III-nitride manufacturing apparatus, even when using a Group III oxide other than _Ga 2 _{O 3,} in the same manner as in the case of producing a GaN crystal with _Ga 2 _{O 3,} to produce a group III nitride crystal be able to. The Group III oxide other than Ga ₂ O _3, an element of Group III, in the case of In (indium), for example, _{an In} 2 _{O 3} and the like, an element of group III, with Al (aluminum) in some cases, for example, _Al 2 _{O 3} and the like. Further, when the group III element is B (boron), for example, B ₂ O ₃ is exemplified, and when the group III element is Tl (thallium), for example, Tl ₂ O ₃ is exemplified. Can be given.

Note that an oxide of a group III element such as Ga ₂ O ₃ has an advantage that it is easy to handle because it is a stable material in the air. On the other hand, instead of an oxide of a Group III element such as Ga ₂ O _3, a Group III element metal such as Ga is prepared, and an oxidizing gas is supplied to the Group III element metal in a heated atmosphere to oxidize. Thus, Ga ₂ O or the like may be generated as a compound gas of a group III element. Some Group III element metals such as Ga have the advantage that high purity materials are generally available at lower cost than Group III element oxides. Furthermore, Group III element metals such as Ga are liquid at low temperatures, so that it is easy to provide a mechanism for continuously supplying materials, and H ₂ O is not generated during oxide gas generation. Advantages such as being able to suppress the deterioration of the crystal quality of these are also mentioned.

For this reason, the group III oxide raw material mounting part 105 functions as a holding part holding the oxide or metal of a group III element. The reducing gas introduction pipe 111 functions as a reactive gas introduction pipe for supplying a reactive gas to an oxide or metal of a group III element. The reactive gas for the Group III element oxide is a reducing gas, and the reactive gas for the Group III element metal is an oxidizing agent such as H ₂ O gas, O ₂ gas, CO ₂ gas, and CO gas. is there. Further, the quartz tube 115 functions as a compound gas supply port for supplying a compound gas of a group III element reacted with the reactive gas into the chamber 101. The exhaust port 108 functions as an exhaust port that exhausts the compound gas and the nitrogen element-containing gas to the outside of the chamber 101.

In addition, the method for producing a Group III nitride crystal in the present disclosure includes a step of generating a Group III element compound gas by reacting a Group III element oxide or metal in a heated atmosphere. When the group III element is Ga, the oxide is Ga ₂ O ₃ , the metal is Ga, and the resulting compound gas is Ga ₂ O (III Group element oxide gas). In addition, the method includes a step of mixing the nitrogen-containing gas having a temperature lower than that of the compound gas with the compound gas. And this method has the process of producing the group III nitride crystal | crystallization by making the said nitrogen element containing gas and the said compound gas react. By having these, productivity can be improved.

  In the following, a more specific example of the above embodiment and its modification and a comparative example for comparison with the example will be described.

Example 1
The group III nitride crystal production apparatus according to Example 1 is the same as the group III nitride crystal production apparatus according to Embodiment 1, and is as shown in FIG. In Example 1, the heating temperature by the substrate heater is 1200 ° C., the heating temperature of the group III oxide raw material placing portion by the raw material heating means is 950 ° C., and hydrogen is supplied as a reducing gas at 10 liters / minute. Thus, Ga ₂ O was used as a source gas at 0.5 liters / minute, ammonia was used as a nitrogen element-containing gas at 5 liters / minute, and the rotation speed of the seed substrate 102 was set at 10 rpm. The nitrogen element-containing gas introduction pipe is disposed on the quartz pipe for supplying the raw material gas, and the opening area of the outlet is set so that the flow rates of the respective outlet gases are equal. Specifically, the height of the quartz tube outlet for deriving the raw material gas was 6 mm, and the height of the nitrogen element-containing gas inlet tube for deriving the nitrogen element-containing gas was 3 mm. Further, a mixing point of the reduced gas of group III oxide and the nitrogen element-containing gas was disposed at a height of 15 mm in the upstream portion of the substrate. Further, the reduced gas of group III oxide and the nitrogen element-containing gas were blown horizontally. Furthermore, the height of the crystal growth space was 45 mm.

(Example 2)
In Example 2, as in Modification 1, the nitrogen element-containing gas introduction pipe was surrounded by a heat insulating material to suppress overheating from the raw material heating means (FIG. 3), and other conditions were the same as in Example 1. .

(Example 3)
In the third embodiment, similarly to the second modification, an inert gas introduction tube is disposed between the nitrogen element-containing gas introduction tube and the quartz tube to suppress overheating from the raw material heating means, and argon is used as the inert gas. By supplying the gas at 2 liters / minute, the mixing region was controlled so that the reduced gas and the nitrogen element-containing gas did not merge in the low temperature region (FIG. 4), and the other conditions were the same as in Example 1.

Example 4
In the fourth embodiment, as in the third modification, in order to control the gas temperature of the nitrogen element-containing gas introduction pipe, a method using a nitrogen element-containing gas heating means is used, and the nitrogen element-containing gas temperature is controlled to 850 ° C. (FIG. 5) The other conditions were the same as in Example 1.

(Comparative Example 1)
In Comparative Example 1, the same conditions as in Example 4 were used except that the nitrogen element-containing gas temperature was controlled at 700 ° C.

(Comparative Example 2)
In Comparative Example 2, the same conditions as in Example 4 were used except that the nitrogen element-containing gas temperature was controlled at 950 ° C.

  Here, the temperature of ammonia gas, which is a nitrogen element-containing gas, under each condition when the temperatures of the Group III oxide and the reducing gas were controlled at 950 ° C. was evaluated. As for the decomposition rate of ammonia gas, the ammonia gas concentration in the vicinity of the exhaust port was measured, and the decomposition rate was obtained from the ammonia gas concentration ratio when the gas temperature was room temperature. The uniformity of the crystal film thickness was evaluated for variation at five points in the plane. The uniformity of the crystal film thickness has less variation when the numerical value is lower, and the film thickness is more uniform. The film thickness was measured at multiple points using a scanning electron microscope (SEM), and the uniformity was (Max (maximum film thickness) −Min (minimum film thickness)) / (2 · Avg. (Film thickness average). Value)).

  In order to suppress the decomposition rate of ammonia, it is better that the ammonia gas temperature is as low as possible. To make the decomposition rate within 10%, it is necessary to suppress it to 850 ° C. or less. However, in order to improve the uniformity of the crystal film thickness, it was determined that the gas temperature difference needs to be controlled within 150 ° C. (in a range where the uniformity of the crystal film thickness is within 10%). The results are shown in Table 1. As shown in Table 1, in all examples, the decomposition rate of ammonia gas is suppressed to within 10%, and the uniformity of the crystal film thickness is also suppressed to within 10%, whereby the single crystal vapor phase growth method is achieved. We were able to confirm that the productivity of was improved.

  As described above, when the group III nitride crystal manufacturing apparatus according to the present disclosure is used, a group III nitride crystal applicable to power semiconductors, heterojunction high-speed electronic devices, optoelectronic devices such as LEDs and lasers, and the like can be obtained. it can.

100 Nitrogen-containing gas introduction pipe 101 Chamber 102 Seed substrate 104 Raw material heating means (first heater)
105 Group III oxide raw material placement part (holding part)
108 Exhaust port 109 Substrate holder 110 Inert gas introduction pipe 111 Reducing gas introduction pipe 112 Substrate heater (second heater)
113 Heat insulating material 114 Nitrogen element containing gas heating means 115 Quartz tube (reduced product gas supply port)

Claims (8)

A chamber;
A nitrogen element-containing gas introduction pipe for introducing a nitrogen element-containing gas into the chamber;
A holding part for holding a Group III element oxide or metal;
A first heater for heating the holding unit;
A reactive gas introduction pipe for supplying a reactive gas to the oxide of the group III element or the metal;
A compound gas supply port for supplying the compound gas of the group III element reacted by the reactive gas into the chamber;
An exhaust port for discharging the compound gas and the nitrogen element-containing gas out of the chamber;
A second heater for heating the seed substrate in the chamber;
With
The group III nitride crystal manufacturing apparatus, wherein a distance between the holding unit and the first heater is closer than a distance between the nitrogen element-containing gas introduction pipe and the first heater.   The group III nitride crystal manufacturing apparatus according to claim 1, wherein the nitrogen element-containing gas introduction pipe is covered with a heat insulating material.   The group III nitride crystal manufacturing apparatus according to claim 1, further comprising an inert gas introduction pipe between the nitrogen element-containing gas introduction pipe and the holding unit. A step of reacting a Group III element oxide or metal in a heated atmosphere to generate a Group III element compound gas;
Mixing the nitrogen-containing gas at a lower temperature than the compound gas and the compound gas;
Reacting the mixed nitrogen-containing gas and the compound gas to produce a group III nitride crystal;
A method for producing a group III nitride crystal having:   The step of mixing is performed after the compound gas and the nitrogen element-containing gas are transferred by an inert gas having a temperature lower than that of the compound gas and higher than that of the nitrogen element-containing gas. The manufacturing method of the group III nitride crystal as described in 1 above.   The method for producing a group III nitride crystal according to claim 4 or 5, wherein a temperature difference between the compound gas and the nitrogen element-containing gas is 150 ° C or less. The method for producing a group III nitride crystal according to any one of claims 4 to 6, wherein the compound gas is Ga ₂ O and the nitrogen-containing gas is ammonia.   The said compound gas is a manufacturing method of the group III nitride crystal as described in any one of Claim 4 to 6 produced | generated by making the metal of the said group III element, and an oxidizing agent react.

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