JP4591415B2 - Method for growing gallium nitride crystal - Google Patents

Description

  The present invention relates to a method for growing a group III nitride crystal and a GaN crystal, and more particularly to a method for growing a group III nitride crystal capable of improving the yield of Ga and a GaN crystal obtained by the method.

  The HVPE (Hydride Vapor Phase Epitaxy) method, in which a gallium nitride (GaN) crystal is grown by reacting gallium chloride gas and ammonia gas on a substrate, is widely used as a GaN crystal growth method.

  In this HVPE method, high-speed growth of about 100 μm / h is possible, and the growth rate of the GaN crystal is higher than that of MOCVD (Metal Organic Chemical Vapor Deposition) method or MBE (Molecular Beam Epitaxy) method. It is much bigger. Therefore, the HVPE method is particularly advantageous as a method for growing a thick GaN crystal or a free-standing GaN substrate.

Here, a method for growing a GaN crystal by the HVPE method includes, for example, blowing a source gas such as a gas in which a carrier gas is mixed with gallium chloride gas or a gas in which carrier gas is mixed with ammonia gas, and exhaust gas (hydrogen chloride). Gas, hydrogen gas, nitrogen gas, ammonia gas, etc.) are discharged (see, for example, Patent Document 1 and Non-Patent Document 1).
Japanese Patent No. 3553583 G. Nataf et al, "Lateral overgrowth of high quality GaN layers on GaN / Al2O3 patterned substrates by halide vapour-phase epitaxy", Journal of Crystal Growth, vol.192, August 1998, p.73

  However, in the conventional HVPE method, since the exhaust gas is exhausted in a state where a large amount of unreacted source gas is contained, the yield of Ga (gallium) (GaN relative to the amount of Ga contained in the source gas) There was a problem that the ratio of the amount of Ga contained in the crystal was very bad. In particular, since high-purity gallium as a raw material for gallium chloride gas is expensive, an improvement in the yield of Ga is important from the viewpoint of reducing the production cost of the GaN crystal.

  Therefore, an object of the present invention is to provide a method for growing a group III nitride crystal capable of improving the yield of Ga and a GaN crystal obtained by the method.

The present invention partitions a space between a main surface of a susceptor for installing a substrate, an opposing surface facing the main surface of the susceptor with a space therebetween, and a main surface of the susceptor and the opposing surface. A gallium nitride crystal is formed on a substrate placed on one main surface of the susceptor by introducing ammonia gas into a growth chamber surrounded by side surfaces and introducing gallium chloride gas from a group III chloride gas outlet. When growing, the area of one main surface of the susceptor is Scm ² , the distance between the main surface of the susceptor and the group III chloride gas outlet is Lcm, and the gas introduced into the growth chamber is in a standard state. It is characterized in that it is a gallium nitride crystal growth method in which the value of S / L / V is 0.11 s / cm ² or more when the total amount is Vcm ³ / s.

Here, in the present invention, the unit of S which is the area of one main surface of the susceptor is cm ² , and the unit of L which is the distance between one main surface of the susceptor and the group III chloride gas jet port is cm. The unit of V, which is the total amount of gas introduced into the growth chamber, is cm ³ / s. Note that cm ³ / s, which is a unit of V, means the volume (cm ³ ) of gas introduced into the growth chamber per second. Further, the value V in the standard state (0 ° C., 1 atm) is used as V which is the total amount of gas introduced into the growth chamber.

  In the present invention, the growth chamber does not need to be completely sealed by the one main surface, the opposing surface, and the side surface of the susceptor.

In the method for growing a group III nitride crystal of the present invention, the growth rate of the gallium nitride crystal is preferably 10 μm / h or more. Here, in the present invention, the growth rate 10 [mu] m / h in the gallium nitride crystal, which means that the gallium nitride crystal is grown at a rate of thickness of 10 [mu] m per hour.

In the gallium nitride crystal growth method of the present invention, the value of S / L / V is preferably 0.5 s / cm ² or more.

In the gallium nitride crystal growth method of the present invention, the value of S / L / V is preferably 1 s / cm ² or more.

In the gallium nitride crystal growth method of the present invention, the temperature of the Group III chloride gas outlet is preferably 1150 ° C. or more and 50 ° C. or more higher than the substrate surface temperature.

In the gallium nitride crystal growth method of the present invention, the temperature of the group III chloride gas outlet is preferably 1250 ° C. or higher and 50 ° C. higher than the surface temperature of the substrate.

In the gallium nitride crystal growth method of the present invention, the temperature of the Group III chloride gas jet outlet is preferably 900 ° C. or lower.

In the gallium nitride crystal growth method of the present invention, the temperature of the spout of the group III chloride gas is preferably at 800 ° C. or less.

In the gallium nitride crystal growth method of the present invention, the surface area of the substrate is preferably 10 cm ² or more.

In the gallium nitride crystal growth method of the present invention, the substrate is placed at a position eccentric from the group III chloride gas outlet, and the substrate is rotated about an axis that is eccentric from the group III chloride gas outlet. It is preferable to grow a gallium nitride crystal.

  In the present invention, the group III nitride crystal may be a nitride of a group III element containing Ga, and if it contains Ga, a group III element other than Ga such as Al (aluminum) or In (indium). May be included.

  In the present invention, the group III chloride gas refers to a gas composed of a chloride of a group III element.

  ADVANTAGE OF THE INVENTION According to this invention, the growth method of the group III nitride crystal which can improve the yield of Ga, and the GaN crystal obtained by the method can be provided.

  Embodiments of the present invention will be described below. In the present invention, the same reference numerals represent the same or corresponding parts.

  FIG. 1 shows a schematic cross-sectional view of a preferred example of the growth chamber used in the present invention. Here, the growth chamber 1 includes a main surface 2 of the susceptor 5 for placing the substrate 6, an opposing surface 3 facing the main surface 2 of the susceptor 5 with a space therebetween, and a main surface of the susceptor 5. It is surrounded by a side surface 4 that partitions the space between the surface 2 and the opposing surface 3.

  Here, the opposing surface 3 is provided with a gas introduction pipe 10 for introducing a group III chloride gas and a gas introduction pipe 11 for introducing ammonia gas below the gas introduction pipe 10. The opening surface at the end portion of the gas introduction pipe 10 on the growth chamber 1 side becomes the group III chloride gas ejection port 8, and the opening surface at the end portion of the gas introduction pipe 11 on the growth chamber 1 side is the ammonia gas ejection port. 9

  Further, the facing surface 3 and the side surface 4 are formed integrally, and no gap exists between the facing surface 3 and the side surface 4. Further, a gap is formed between the susceptor 5 and the side surface 4, and this gap serves as an exhaust port 7.

  And after installing the board | substrate 6 on one main surface 2 of the susceptor 5 inside the growth chamber 1 and heating the board | substrate 6, while introducing ammonia gas into the growth chamber 1 from the jet port 9 of ammonia gas, III Group III chloride gas is introduced from the group 8 chloride gas outlet 8. Here, the group III chloride gas and the ammonia gas may be diluted with a rare gas, a nitrogen gas, a hydrogen gas, or at least two of these dilution gases, respectively. Further, a gas such as a rare gas, nitrogen gas, hydrogen gas or doping gas may be introduced into the growth chamber 1 separately from the group III chloride gas and ammonia gas, if necessary. Thereby, a group III nitride crystal can be grown on the substrate 6.

In the present invention, when a group III nitride crystal is grown on the substrate 6, the area of the one principal surface 2 of the susceptor 5 is S (cm ² ), and the one principal surface 2 of the susceptor 5 and the group III chloride gas. Let L (cm) be the distance to the jet outlet 8 (distance in the direction perpendicular to the main surface 2 of the susceptor 5), and V (cm ³ / s) the total amount of gas introduced into the growth chamber 1 in the standard state when a, is characterized in that the value of S / L / V 0.1 (s / cm 2) or more. This is because, as a result of intensive studies by the present inventor, by setting the above S / L / V value to 0.1 (s / cm ² ) or more, in particular, a group III nitride crystal containing Ga is grown. It has been found that the yield of Ga can be improved, and the present invention has been completed.

  FIG. 2 shows a schematic cross-sectional view of another preferred example of the growth chamber used in the present invention. Here, the gas introduction pipe 10 and the gas introduction pipe 11 protrude into the growth chamber 1, and the group III chloride gas ejection port 8 exists in the growth chamber 1. In the growth chamber 1 having such a configuration, the distance L between one main surface 2 of the susceptor 5 and the group III chloride gas jetting port 8 is the length shown in FIG.

  FIG. 3 shows a schematic cross-sectional view of another preferred example of the growth chamber used in the present invention. Here, the gas introduction pipe 10 and the gas introduction pipe 11 are provided on the side surface 4 of the growth chamber 1, and the group III chloride gas ejection port 8 exists on the side surface 4. In the growth chamber 1 having such a configuration, the distance L between the one main surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 is the length shown in FIG. Here, as shown in FIG. 3, the end of the group L chloride gas outlet 8 side of the distance L is the length d of the group III chloride gas outlet 8 (with respect to the one main surface 2 of the susceptor 5). This is a location (1 / 2d position) corresponding to half of the length in the perpendicular direction.

  FIG. 4 shows a schematic cross-sectional view of another preferred example of the growth chamber used in the present invention. Here, the gas introduction pipe 10 and the gas introduction pipe 11 are provided on the side surface 4 of the growth chamber 1, and the gas introduction pipe 10 and the gas introduction pipe 11 protrude from the growth chamber 1. . In the growth chamber 1 having such a configuration, the distance L between the one principal surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 is the length shown in FIG. Here, the end of the group III chloride gas outlet 8 on the side of the distance L is, as shown in FIG. 4, the length d of the group 8 chloride gas outlet 8 (with respect to the main surface 2 of the susceptor 5). This is a location (1 / 2d position) corresponding to half of the length in the perpendicular direction.

  FIG. 5 shows a schematic cross-sectional view of another preferred example of the growth chamber used in the present invention. Here, the gas introduction pipe 10 to which the gas introduction pipe 11 is connected is provided on the opposing surface 3 of the growth chamber 1. As described above, when the group III chloride gas and the ammonia gas are mixed before being introduced into the growth chamber 1, a gas for introducing a gas in which at least the group III chloride gas and the ammonia gas are mixed is introduced. The opening surface at the end of the introduction tube 10 on the growth chamber 1 side is a group III chloride gas ejection port 8. Accordingly, in the growth chamber 1 having such a configuration, the distance L between the one main surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 is the length shown in FIG.

  FIG. 6 shows a schematic top perspective view of another preferred example of the growth chamber used in the present invention. Here, the surface of the substrate 6 installed on the main surface 2 of the susceptor 5 and the group 8 chloride gas jetting port 8 do not face each other, and are in a positional relationship shifted from each other in the direction of the side surface 4. In the growth chamber 1 having such a configuration, the distance L between one main surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 has a length shown in FIG.

  In order to increase the value of S / L / V, at least one of L and V may be decreased when S is constant. However, if L is made too small, a group III nitride crystal such as a GaN crystal grows in the vicinity of the group 8 chloride gas ejection port 8, thereby inhibiting normal growth of the group III nitride crystal on the substrate 6. There is a fear. In order to prevent the growth rate of the group III nitride crystal on the substrate 6 from decreasing while decreasing V (in order to maintain a growth rate of 10 μm / h from a practical aspect), the ratio of the dilution gas is set to It is necessary to reduce the concentration of the group III chloride gas such as gallium chloride gas. However, even in this case, there is a possibility that a group III nitride crystal such as a GaN crystal grows in the vicinity of the group 8 chloride gas outlet 8 and inhibits the normal growth of the group III nitride crystal on the substrate 6. is there.

Therefore, in order to increase the value of the above S / L / V, particularly in order to set it to 1 (s / cm ² ) or more, the growth of the group III nitride crystal in the vicinity of the group 8 chloride gas outlet 8 is performed. It is important to suppress this.

  Here, in order to suppress the growth of the group III nitride crystal in the vicinity of the group III chloride gas ejection port 8, the temperature of the group III chloride gas ejection port 8 is 1150 ° C. or more, preferably 1250 ° C. or more. In addition, the present inventors have found that it is effective to set the temperature of the group 8 chloride gas outlet 8 to be higher by 50 ° C. or more than the surface temperature of the substrate 6 during the growth of the group III nitride crystal. I found it. Since the surface temperature of the substrate 6 is generally in the range of 900 ° C. to 1100 ° C. when the group III nitride crystal is grown by the HVPE method, the temperature of the group 8 chloride gas outlet 8 is 1150 ° C. or higher. Preferably, when heated to 1250 ° C. or higher, the growth of the group III nitride crystal is enhanced by providing a temperature difference of 50 ° C. or higher between the temperature of the group 8 chloride gas outlet 8 and the surface temperature of the substrate 6. There seems to be no obstacle.

  Further, since it has been known for a long time that the deposition rate of GaN crystals decreases on the surface at a temperature of 900 ° C. or lower, particularly 800 ° C. or lower, the temperature of the Group III chloride gas ejection port 8 is preferably 900 It is considered that the growth of the group III nitride crystal in the vicinity of the group 8 chloride gas outlet 8 can also be suppressed by setting the temperature to be equal to or lower than ° C, more preferably equal to or lower than 800 ° C.

  In addition, when a group III nitride crystal grows on the opposing surface 3 and the side surface 4, it is considered that the yield of Ga decreases accordingly. Therefore, preferably, when the group III nitride crystal is grown, the temperature of the facing surface 3 or the temperature of the side surface 4 is more preferably set to 1150 ° C. or more, preferably 1250 ° C. or more. As a result, it is possible to suppress the growth of the group III nitride crystal on the facing surface 3, the side surface 4, or both of these surfaces, so that the yield of Ga tends to be further improved. For the same reason as described above, the temperature of the opposing surface 3 or the temperature of the side surface 4, more preferably the temperature of both surfaces is preferably 900 ° C. or lower, more preferably 800 ° C. or lower. The growth of the group III nitride crystal on the opposing surface 3, the side surface 4, or both of these surfaces can be suppressed.

Further, in the case where it is possible to suppress the growth of the group III nitride crystal on the facing surface 3, the side surface 4, or both of these surfaces, the growth chamber 1 shown in FIGS. The space on the side opposite to the substrate 6 side when viewed from the jet port 8 is considered to have only a gas stagnant and hardly affect the growth of the group III nitride crystal, and thus the presence thereof can be ignored. This is considered to be the reason why L can be defined as shown in FIGS. Here, when the facing surface 3, the side surface 4, or both of these surfaces are set to 1150 ° C. or higher, preferably 1250 ° C. or higher, the yield of Ga increases as the S / L / V value increases. Therefore, the S / L / V value is preferably 0.5 (s / cm ² ) or more, and more preferably 1 (s / cm ² ) or more.

  In the present invention, the group III chloride gas and the ammonia gas introduced into the growth chamber 1 reach the surface of the substrate 6 which is a low temperature part by transport by diffusion, and grow there as a group III nitride crystal. Here, in the transport by diffusion, the concentration of the group III chloride gas is increased in the region corresponding to the group 8 chloride gas outlet 8 inside the growth chamber 1, and the group III chloride is also formed on the substrate 6. The region corresponding to the gas outlet 8 has a group III nitride crystal growing faster than the other regions, and the group III nitride crystal having a uniform thickness tends not to be obtained.

  Therefore, in order to obtain a group III nitride crystal having a uniform thickness, the substrate 6 is placed at a position eccentric from the group 8 chloride gas jet 8 and the substrate 6 is placed in the group III chloride jet 8. It is preferable to grow a group III nitride crystal while rotating about an eccentric axis. For example, as shown in the schematic cross-sectional view of FIG. 7, this is a first perpendicular line that is a perpendicular line to the surface of the substrate 6 (the surface on which the group III nitride crystal grows) and passes through the center of this surface. 14 and the substrate 6 are placed so that the second normal 15 which is a perpendicular to the group 8 chloride gas outlet 8 and passes through the center of the group III chloride gas outlet 8 does not overlap. This can be done by growing a group III nitride crystal while rotating the substrate 6 around the first perpendicular line 14.

Since the present invention is intended to improve the yield of Ga, it is considered that the present invention is particularly useful when the surface area of the substrate 6 is 10 cm ² or more.

  The group III nitride crystal obtained by the present invention is an electron such as a light emitting element such as a light emitting diode or a laser diode, a rectifier, a bipolar transistor, a field effect transistor, or a HEMT (High Electron Mobility Transistor). Element, temperature sensor, pressure sensor, radiation sensor, semiconductor sensor such as visible-ultraviolet light detector, SAW device (Surface Acoustic Wave Device), vibrator, resonator, oscillator, MEMS (Micro Electro Mechanical System) ) Widely used as a substrate for devices such as parts or piezoelectric actuators.

  In the above description, the facing surface 3 and the side surface 4 are integrally formed, and an example in which no gap exists between the facing surface 3 and the side surface 4 has been described. There may be a gap between the facing surface 3 and the side surface 4.

  In the above description, an example in which a gap is provided between the main surface 2 and the side surface 4 of the susceptor 5 and the gap is used as the exhaust port 7 has been described. An exhaust port may be provided in another part of the growth chamber 1 without providing a gap between the main surface 2 and the side surface 4, and an exhaust port that is a gap between the one main surface 2 and the side surface 4 of the susceptor 5. 7 and an exhaust port may be provided in another part of the growth chamber 1.

  In the above, the gas introduction pipe 10 for introducing the group III chloride gas and the gas introduction pipe 11 for introducing the ammonia gas are arranged side by side. However, in the present invention, the group III is not necessarily limited. It is not necessary to arrange the gas introduction pipe 10 for introducing the chloride gas and the gas introduction pipe 11 for introducing the ammonia gas side by side.

  In the above description, the surface of the substrate 6 is oriented sideways. However, in the present invention, the surface is not limited to the sideways orientation, and may be downward or upward.

Example 1
A GaN crystal was grown at normal pressure by the HVPE method using a crystal growth furnace 300 whose outline is shown in FIG.

The crystal growth furnace 300 includes a growth chamber 1 surrounded by a principal surface 2 (area S = 38.465 cm ² ), a facing surface 3 and a side surface 4 of a disc-shaped susceptor 5 having a diameter of 7 cm. Here, the opposed surface 3 is provided with a gas introduction pipe 10 for introducing a group III chloride gas and a gas introduction pipe 11 for introducing ammonia gas below the gas introduction pipe 10. Further, the facing surface 3 and the side surface 4 are formed integrally, and no gap exists between the facing surface 3 and the side surface 4. Further, a gap is formed between the susceptor 5 and the side surface 4, and this gap serves as an exhaust port 7. In the present embodiment, the distance L between the one principal surface 2 of the susceptor 5 and the group 8 chloride gas ejection port 8 was set to 15 cm. The susceptor 5 has a circular flat main surface 2 having a diameter of 7 cm, and members for holding the substrate are attached to both ends of the main surface 2.

  The crystal growth furnace 300 also introduces a synthesis chamber 20 for synthesizing gallium chloride gas, a gas introduction pipe 21 for introducing hydrogen chloride gas into the synthesis chamber 20, and an ammonia gas outside the growth chamber 1. And a gas introduction pipe 19 for the purpose. A Ga boat 16 containing Ga is installed in the synthesis chamber 20, and a heater 17 is installed around the growth chamber 1, the synthesis chamber 20, and the gas introduction pipes 10, 11, 19, and 21. Has been. The susceptor 5 is provided with a rotating shaft 18.

  Further, the facing surface 3 and the side surface 4 constituting the growth chamber 1 are each composed of ceramics incorporating a carbon heater (in FIG. 8, detailed description of a power supply line and a thermocouple to the carbon heater is omitted). The opposing surface 3 and the side surface 4 can be heated separately from the susceptor 5.

  In the crystal growth furnace 300 having such a configuration, first, a sapphire substrate 6 a having a diameter of 2 inches was installed in the center of the surface of the susceptor 5. Next, the sapphire substrate 6a is heated to maintain the surface temperature of the sapphire substrate 6a at 1050 ° C., and a first perpendicular that is a perpendicular to the surface of the sapphire substrate 6a and passes through the center of the surface of the sapphire substrate 6a. A GaN crystal is grown on the surface of the sapphire substrate 6a by introducing gallium chloride gas and ammonia gas into the growth chamber 1 in a state where the sapphire substrate 6a is rotated at a speed of 60 rpm by the rotating shaft 18 with the axis as the axis. It was.

  Here, the GaN crystal was grown in each case where the facing surface 3 and the side surface 4 were heated or not. The temperature in the growth chamber 1 when the opposing surface 3 and the side surface 4 were not heated was 1050 ° C. Further, when the opposing surface 3 and the side surface 4 were heated, the temperature of the opposing surface 3 and the side surface 4 was set to 1300 ° C., respectively. Therefore, the temperature in the vicinity of the Group 8 chloride gas outlet 8 when the facing surface 3 and the side surface 4 are heated is also heated to 1300 ° C.

Further, gallium chloride gas having a flow rate of 200 sccm is introduced into the growth chamber 1 together with hydrogen gas having a flow rate of 200 sccm as a dilution gas, and ammonia gas having a flow rate of 500 sccm is combined with hydrogen gas having a flow rate of 500 sccm as dilution gas. Was introduced. Accordingly, in this embodiment, the total amount V in the standard state of the gas introduced into the growth chamber 1 is 1400 sccm, i.e., had a ^{1400/60 (cm 3 / s} ). The gallium chloride gas heats the Ga boat 16 installed in the synthesis chamber 20, introduces hydrogen chloride gas into the synthesis chamber 20 through the gas introduction pipe 21, and Ga and hydrogen chloride in the Ga boat 16 are introduced. It was produced by reacting with gas. Here, the hydrogen chloride gas was introduced into the synthesis chamber 20 together with the hydrogen gas as the dilution gas.

  In addition, ammonia gas (purity: 100%) having a flow rate of 500 sccm was supplied from the gas introduction pipe 19 to the outside of the growth chamber 1. This is to suppress the exhaust of ammonia gas due to diffusion from the exhaust port 7 of the growth chamber 1.

  In addition, the second perpendicular, which is a perpendicular to the group III chloride gas jet 8 and passes through the center of the group III chloride gas jet 8, is located 2 cm above the first perpendicular. The third perpendicular, which is a perpendicular to the ammonia gas jet 9 and passes through the center of the ammonia gas jet 9, was located 2 cm above the first perpendicular. Accordingly, in this embodiment, the sapphire substrate 6a is installed at a position eccentric from the group 8 chloride gas jet 8 and the sapphire substrate 6a is centered on the axis 8 that is eccentric from the group III chloride gas jet 8. The GaN crystal was grown while rotating. Here, the ammonia gas jet port 9 is installed below the group III chloride gas jet port 8, and this is because a heavy gas (gallium chloride gas) is introduced from above, and a light gas (ammonia gas) ) Is introduced from below, the gas concentration in the growth chamber 1 is likely to be uniform.

  The growth mass (g) and growth rate (μm / h) of the GaN crystal grown as described above were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example. Here, the growth rate is a value obtained by dividing the thickness of the finally grown GaN crystal by the total growth time of the GaN crystal, and shows an average growth rate of the GaN crystal.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 6.4 (g), and the growth rate of the GaN crystal is 27.05 (μm / h). )Met. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 5.4 (g), and the growth rate of the GaN crystal is 22.83 ( μm / h).

(Example 2)
A GaN crystal was grown by the same method and the same conditions as in Example 1 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas ejection port 8 was set to 10 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 9.2 (g), and the growth rate of the GaN crystal is 38.89 (μm / h). )Met. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 6.4 (g), and the growth rate of the GaN crystal is 27.05 ( μm / h).

(Example 3)
A GaN crystal was grown by the same method and the same conditions as in Example 1 except that the distance L between the one principal surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 was set to 5 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 12.6 (g), and the growth rate of the GaN crystal is 53.26 (μm / h). )Met. Further, as shown in Table 1, when the opposed surface 3 and the side surface 4 were not heated, the growth mass of the GaN crystal was 9.2 (g), and the growth rate of the GaN crystal was 38.89 ( μm / h).

Example 4
A GaN crystal was grown by the same method and the same conditions as in Example 3 except that the flow rate of hydrogen gas introduced together with gallium chloride gas and the flow rate of hydrogen gas introduced together with ammonia gas were each halved. . Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 15.6 (g), and the growth rate of the GaN crystal is 65.95 (μm / h). )Met. Further, as shown in Table 1, when the opposed surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 11.4 (g), and the growth rate of the GaN crystal is 48.19 ( μm / h).

(Example 5)
A GaN crystal was grown by the same method and the same conditions as in Example 4 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas jet 8 was set to 4 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 19.4 (g), and the growth rate of the GaN crystal is 82.01 (μm / h). )Met. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 13.6 (g), and the growth rate of the GaN crystal is 57.49 ( μm / h).

(Example 6)
A GaN crystal was grown by the same method and the same conditions as in Example 4 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas ejection port 8 was set to 3 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 22.2 (g), and the growth rate of the GaN crystal is 93.85 (μm / h). )Met. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 13.4 (g), and the growth rate of the GaN crystal is 56.65 ( μm / h).

(Example 7)
A GaN crystal was grown by the same method and the same conditions as in Example 4 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas jetting port 8 was set to 2 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 26 (g), and the growth rate of the GaN crystal is 109.91 (μm / h). there were. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 were not heated, the growth mass of the GaN crystal was 10.4 (g), and the growth rate of the GaN crystal was 43.96 ( μm / h).

(Example 8)
A GaN crystal was grown by the same method and the same conditions as in Example 4 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas jetting port 8 was set to 1 cm. Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 26.6 (g), and the growth rate of the GaN crystal is 112.45 (μm / h). )Met. Further, as shown in Table 1, when the opposed surface 3 and the side surface 4 were not heated, the growth mass of the GaN crystal was 6.5 (g), and the growth rate of the GaN crystal was 27.48 ( μm / h).

Example 9
A heater was incorporated in the susceptor 5 of the crystal growth furnace shown in FIG. 8, and piping for circulating a cooling gas was incorporated in the opposing surface 3 and the side surface 4. A thermocouple was incorporated on the central axis of the growth chamber 1 in order to measure the temperature of the susceptor 5 and the facing surface 3.

  The gas conditions and the dimensional conditions of the individual members of the crystal growth furnace are the same as those in the fourth embodiment. Regarding the temperature conditions, the heating temperature of the growth chamber 1 by the heater 17 is set to 800 ° C. and incorporated in the susceptor 5. The surface temperature of the sapphire substrate 6a was heated to 1050 ° C. by the heater.

  A GaN crystal was grown under the same conditions as in Example 4. In this embodiment, the cooling gas is not circulated, and the temperature of the facing surface 3 when the cooling gas is not circulated is 830 ° C. (that is, at the group 8 chloride gas jet port 8. A GaN crystal was grown under conditions of a temperature of 830 ° C. Although the heating temperature by the heater 17 was 800 ° C., the counter surface 3 was heated to 830 ° C. by the heater incorporated in the susceptor 5.

  Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 2 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 2, the growth mass of the GaN crystal in Example 9 was 15.1 (g), and the growth rate of the GaN crystal was 63.84 (μm / h). The growth rate of the GaN crystal in Example 9 was almost the same as the growth rate of the GaN crystal when the facing surface 3 and the side surface 4 were heated in Example 4.

(Example 10)
The crystal growth furnace having the same configuration as that of Example 9 was used, and the temperature of the opposing surface 3 was controlled to 750 ° C. by circulating a cooling gas inside the opposing surface 3 and the side surface 4 (that is, group III chloride). The GaN crystal was grown while controlling the temperature of the product gas outlet 8 at 750 ° C. Other growth conditions were the same as in Example 9.

  Then, in the same manner as in Example 1, the growth mass (g) and the growth rate (μm / h) of the grown GaN crystal were investigated. Table 2 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 2, the growth mass of the GaN crystal in Example 10 was 16.8 (g), and the growth rate of the GaN crystal was 71.06 (μm / h). The growth rate of the GaN crystal in Example 10 was slightly higher than the growth rate of the GaN crystal in the case where the facing surface 3 and the side surface 4 were heated in Example 4.

(Comparative Example 1)
The distance L between the main surface 2 of the susceptor 5 and the group III chloride gas ejection port 8 was set to 20 cm, and the flow rate of ammonia gas and the flow rate of hydrogen gas as a dilution gas of ammonia gas were each doubled. Except for this, a GaN crystal was grown by the same method and the same conditions as in Example 1. In the same manner as in Example 1, the growth mass (g) and growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 0.2 (g), and the growth rate of the GaN crystal is 0.85 (μm / h). )Met. In addition, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 0.2 (g), and the growth rate of the GaN crystal is 0.85 ( μm / h).

(Comparative Example 2)
A GaN crystal was grown by the same method and the same conditions as in Comparative Example 1 except that the distance L between the main surface 2 of the susceptor 5 and the group 8 chloride gas jetting port 8 was set to 15 cm. In the same manner as in Example 1, the growth mass (g) and growth rate (μm / h) of the grown GaN crystal were investigated. Table 1 shows the results of the growth mass and growth rate of the GaN crystal in this example.

  As shown in Table 1, when the facing surface 3 and the side surface 4 are heated, the growth mass of the GaN crystal is 0.4 (g), and the growth rate of the GaN crystal is 1.69 (μm / h). )Met. Further, as shown in Table 1, when the opposing surface 3 and the side surface 4 are not heated, the growth mass of the GaN crystal is 0.4 (g), and the growth rate of the GaN crystal is 1.69 ( μm / h).

(Evaluation)
As is apparent from Table 1, the S / L / V value is 0.1 both in the case where the facing surface 3 and the side surface 4 are heated and in the case where the facing surface 3 and the side surface 4 are not heated. In Examples 1 to 8 which are (s / cm ² ) or more, compared to Comparative Examples 1 to 2 in which the value of S / L / V is less than 0.1 (s / cm ² ), the growth of the GaN crystal Mass increased greatly. Here, in Examples 1 to 8 and Comparative Examples 1 and 2, since the introduction amounts of gallium chloride gas are all the same, the yield of Ga is improved as the growth mass of the GaN crystal is increased. Will be shown. Therefore, in Examples 1-8, both the case where the opposing surface 3 and the side surface 4 are heated and the case where the opposing surface 3 and the side surface 4 are not heated are compared with Comparative Examples 1 and 2, It was confirmed that the yield of Ga was improved.

  Further, as apparent from Table 1, in Examples 1 to 8, when the facing surface 3 and the side surface 4 were heated, the GaN crystal was compared with the case where the facing surface 3 and the side surface 4 were not heated. It has been confirmed that the growth mass of is increased and the yield of Ga is improved.

  FIG. 9 shows Examples 1 to 8 and Comparative Examples 1 to 2 and Example 9 shown in Table 1 when the facing surface 3 and the side surface 4 are heated and when the facing surface 3 and the side surface 4 are not heated. The figure which put together the relationship between the value of S / L / V of -10 and the growth mass of a GaN crystal is shown. In FIG. 9, the horizontal axis indicates the value of S / L / V, and the vertical axis indicates the growth mass of the GaN crystal.

As shown in FIG. 9, when the facing surface 3 and the side surface 4 are heated, when the value of S / L / V is less than 0.1 (s / cm ² ), the GaN crystal almost grows. However, it can be seen that the GaN crystal grows greatly when it becomes 0.1 (s / cm ² ) or more. It can also be seen that the growth mass of the GaN crystal increases as the value of S / L / V increases. This indicates that the yield of Ga improves with an increase in the value of S / L / V.

Further, as shown in FIG. 9, even when the facing surface 3 and the side surface 4 are not heated, if the value of S / L / V is less than 0.1 (s / cm ² ), the GaN crystal is Although it has hardly grown, it turns out that the GaN crystal has grown greatly when it becomes 0.1 (s / cm ² ) or more. However, until the value of S / L / V reaches 0.5 (s / cm ² ), the growth mass of the GaN crystal increases as the value of S / L / V increases. When the value exceeds 0.55 (s / cm ² ), the growth mass of the GaN crystal decreases. This is considered due to an increase in the number of GaN crystals grown on the opposite surface side.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the growth method of the group III nitride crystal which can improve the yield of Ga, and the GaN crystal obtained by the method can be provided.

It is typical sectional drawing of a preferable example of the growth chamber used for this invention. It is typical sectional drawing of another preferable example of the growth chamber used for this invention. It is typical sectional drawing of another preferable example of the growth chamber used for this invention. It is typical sectional drawing of another preferable example of the growth chamber used for this invention. It is typical sectional drawing of another preferable example of the growth chamber used for this invention. It is a typical top perspective view of another preferable example of the growth chamber used for the present invention. It is a typical sectional view for illustrating eccentricity in the present invention. It is the schematic of an example of the crystal growth furnace used for this invention. S / L / V of Examples 1 to 8 and Comparative Examples 1 to 2 and Examples 9 to 10 shown in Table 1 when the facing surface and the side surface are heated and when the facing surface and the side surface are not heated It is a figure which shows the relationship between the value of and the growth mass of GaN crystal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Growth chamber, 2 main surface, 3 opposing surface, 4 side surface, 5 susceptor, 6 board | substrate, 6a sapphire substrate, 7 exhaust port, 8 group III chloride gas jet port, 9 ammonia gas jet port, 10, 11, 19, 21 Gas introduction pipe, 14 1st perpendicular line, 15 2nd perpendicular line, 16 Ga boat, 17 heater, 18 rotating shaft, 20 synthesis chamber, 300 crystal growth furnace.

Claims (10)

One main surface of the susceptor for installing the substrate, a facing surface facing the one main surface of the susceptor with a space therebetween, and a side surface that partitions a space between the one main surface of the susceptor and the facing surface And introducing a gallium nitride crystal on a substrate placed on one main surface of the susceptor by introducing ammonia gas into a growth chamber surrounded by gallium chloride gas from a group III chloride gas outlet. When growing, the area of one principal surface of the susceptor is Scm ² , the distance between the one principal surface of the susceptor and the group III chloride gas outlet is Lcm, and the gas introduced into the growth chamber A method for growing a gallium nitride crystal, wherein a value of S / L / V is set to 0.11 s / cm ² or more when a total amount in a standard state is Vcm ³ / s. 2. The method for growing a gallium nitride crystal according to claim 1, wherein the growth rate of the gallium nitride crystal is 10 [mu] m / h or more. 3. The method for growing a gallium nitride crystal according to claim 1, wherein the value of S / L / V is 0.5 s / cm ² or more. The gallium nitride crystal growth method according to claim 1, wherein the value of S / L / V is 1 s / cm ² or more. The nitriding according to any one of claims 1 to 4, wherein the temperature of the group III chloride gas ejection port is 1150 ° C or higher and 50 ° C or higher than the surface temperature of the substrate. A method for growing gallium crystals. The nitriding according to any one of claims 1 to 4, wherein the temperature of the group III chloride gas jetting port is 1250 ° C or higher and 50 ° C or higher than the surface temperature of the substrate. A method for growing gallium crystals. The method for growing a gallium nitride crystal according to any one of claims 1 to 4, wherein the temperature of the Group III chloride gas ejection port is 900 ° C or lower. The method for growing a gallium nitride crystal according to any one of claims 1 to 4, wherein a temperature of the group III chloride gas jetting port is 800 ° C or lower. The method for growing a gallium nitride crystal according to any one of claims 1 to 8, wherein the surface area of the substrate is 10 cm ² or more. The substrate is placed at a position eccentric from the group III chloride gas ejection port, and a gallium nitride crystal is grown while the substrate is rotated about an axis eccentric with the group III chloride gas ejection port. The method for growing a gallium nitride crystal according to any one of claims 1 to 9, wherein

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