JP4921855B2 - Production method - Google Patents

Description

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

  At present, most of InGaAlN (group III nitride semiconductor) -based devices used as ultraviolet, violet to blue to green light sources have sapphire and silicon carbide (SiC) as substrates, and MOCVD (organometallic) is formed on the substrate. Chemical vapor deposition) and MBE (molecular beam crystal growth) are used.

  Thus, when sapphire and silicon carbide are used as the substrate, the thermal expansion coefficient and the lattice constant are greatly different between the substrate and the group III nitride semiconductor, so that many crystal defects are present in the group III nitride semiconductor. Will be included. This crystal defect degrades device characteristics, and is directly related to defects such as short lifetime and high operating power in a light emitting device, for example.

  Further, since the sapphire substrate is an insulator, it has been impossible to take out the electrode from the substrate side like a conventional light emitting device. Thereby, it is necessary to take out the electrode from the group III nitride semiconductor side. As a result, there is a disadvantage that the area of the device is increased and the cost is increased. And when the area of a device becomes large, the new problem of the curvature of a board | substrate accompanying the combination of a dissimilar material called a sapphire substrate and a group III nitride semiconductor will generate | occur | produce.

  Further, the group III nitride semiconductor device fabricated on the sapphire substrate is difficult to separate by chip cleavage, and it is not easy to obtain a resonator end face required in a laser diode (LD). Therefore, at present, the end face of the resonator is formed by dry etching or separating the sapphire substrate into a shape close to cleavage after polishing to a thickness of 100 μm or less. Therefore, unlike the conventional LD, it is difficult to perform the formation of the resonator end face and the chip separation in a single process, resulting in high costs due to the complicated process.

  In order to solve these problems, it has been proposed to reduce crystal defects by devising such as selectively growing a group III nitride semiconductor in a lateral direction on a sapphire substrate. This makes it possible to reduce crystal defects, but the problems relating to the insulating properties of the sapphire substrate and the aforementioned difficulty of cleavage still remain.

  In order to solve these problems, a gallium nitride (GaN) substrate that is the same as the material for crystal growth on the substrate is optimal. Therefore, various methods for crystal growth of bulk GaN by vapor phase growth and melt growth have been proposed. However, a GaN substrate having a high quality and a practical size has not been realized yet.

As one method for realizing a GaN substrate, a GaN crystal growth method using sodium (Na) as a flux has been proposed (Patent Document 1). In this method, sodium azide (NaN ₃ ) and metallic Ga are used as raw materials, and NaN ₃ and metallic Ga are placed in a nitrogen atmosphere in a stainless steel reaction vessel (inner dimensions: inner diameter = 7.5 mm, length = 100 mm). The GaN crystal grows by encapsulating the reaction vessel and holding the reaction vessel at a temperature of 600 to 800 ° C. for 24 to 100 hours.

This method is characterized in that crystal growth is possible at a relatively low temperature of 600 to 800 ° C., and the pressure in the container is relatively low at about 100 kg / cm ² at most, which is a practical growth condition.

  Recently, a high-quality group III nitride crystal has been realized by reacting a mixed melt of an alkali metal and a group III metal with a group V raw material containing nitrogen (Patent Document 2).

Further, a mixed melt containing metal Na and metal Ga is put in a crucible, the crucible is placed in a reaction vessel, and the metal Na melt is held outside the crucible in the reaction vessel, and vapor of metal Na A method of growing a GaN crystal by increasing the pressure is also known (Patent Document 3).
US Pat. No. 5,868,837 JP 2001-58900 A JP 2005-263571 A

  However, in the conventional crystal manufacturing apparatus for growing a GaN crystal, it is difficult to keep the mixing ratio of metal Na and metal Ga in the mixed melt substantially constant during the growth of the GaN crystal. There is. That is, metal Na has a high vapor pressure and may diffuse from the mixed melt to the outside, or conversely, from the outside to the mixed melt. Further, the metal Ga is consumed from the mixed melt as the crystal growth proceeds. As a result, it becomes difficult to suppress fluctuations in the mixing ratio of metal Na and metal Ga in the mixed melt.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a crystal manufacturing apparatus for manufacturing a group III nitride crystal by suppressing a variation in the mixing ratio between an alkali metal and a group III metal. Is to provide.

  Another object of the present invention is to provide a production method for producing a group III nitride crystal while suppressing fluctuations in the mixing ratio between an alkali metal and a group III metal.

According to the present invention, there is provided a manufacturing method for manufacturing a group III nitride crystal using a mixed melt containing an alkali metal and a group III metal and held in a crucible in a container, and a nitrogen source gas. A first step in which the alkali metal and the group III metal are set in the crucible in an active gas or nitrogen gas atmosphere; and the nitrogen source gas is in the container space in the inert gas or nitrogen gas atmosphere. A second step of setting the alkali metal in at least one of a first region existing on a path supplied to the container and a second region communicating with the container space and different from the first region; A third step of supplying a nitrogen source gas to the vessel space, a fourth step of heating the crucible to the crystal growth temperature, and setting the temperature of the alkali metal melt present in the first region to the condensation temperature. Control And a fifth step of controlling the temperature of the alkali metal present in the second region to the evaporation restraining temperature, the evaporation restraining temperature, the alkali metal melt and a second is present in said first region The vapor pressure of the alkali metal evaporating from at least one of the alkali metal melts existing in the region is substantially the same as the vapor pressure of the alkali metal evaporating from the mixed melt, and the condensation temperature is It is the temperature that accumulates in the first region as a metal melt .

Preferably, in the manufacturing method, the temperature of the crucible is heated to the crystal growth temperature for a predetermined period, the temperature of the alkali metal melt existing in the first region is controlled to the condensation temperature, and the first And a sixth step of controlling the temperature of the alkali metal melt existing in the region 2 to the evaporation suppression temperature.

Preferably, in the manufacturing method, when the predetermined period has elapsed, the temperature of the alkali metal melt existing in the first region is controlled to an evaporation promoting temperature, and the alkali metal melt present in the second region is controlled. A seventh step of controlling to the condensation temperature is further provided, and the evaporation promotion temperature is a temperature at which the alkali metal melt moves to another part by gas phase transport.

  Preferably, the manufacturing method further includes a sixth step in which a seed crystal is held so as to be in contact with an interface between the mixed melt and the container space or soaked in the mixed melt. In the third step, the nitrogen source gas is supplied to the container space so that the pressure in the container space is set to a seed crystal growth pressure at which a group III nitride crystal grows from the seed crystal, In the step, the crucible is heated so that the temperature of the crucible is set to a seed crystal growth temperature at which a group III nitride crystal grows from the seed crystal.

  Preferably, in the third step, the nitrogen source gas is supplied to the container space so that the pressure in the container space is set to a nucleation pressure at which multinucleation occurs from the interface between the mixed melt and the crucible, In the fourth step, the crucible is heated so that the temperature of the crucible is set to a nucleation temperature at which multinucleation occurs from the interface between the mixed melt and the crucible.

  In this invention, the alkali metal vapor from the mixed melt containing the alkali metal and the group III metal is suppressed by the alkali metal melt of at least one of the first and second alkali metal melts, and the group III nitride Crystals are grown.

  Therefore, according to the present invention, it is possible to produce a group III nitride crystal while suppressing a variation in the mixing ratio between the alkali metal and the group III metal in the mixed melt.

  Further, according to the present invention, the vapor pressure of the alkali metal evaporated from the mixed melt containing the alkali metal and the group III metal and the evaporation from at least one alkali metal melt of the first and second alkali metal melts. The group III nitride crystal is grown with substantially the same vapor pressure of the alkali metal. In this case, during the growth of the group III nitride crystal, the movement of the alkali metal from the mixed melt to the alkali metal melt and the movement of the alkali metal from the alkali metal melt to the mixed melt are balanced.

  Therefore, according to the present invention, it is possible to produce a group III nitride crystal while suppressing a variation in the mixing ratio between the alkali metal and the group III metal in the mixed melt.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a schematic cross-sectional view of a crystal manufacturing apparatus according to Embodiment 1 of the present invention. Referring to FIG. 1, a crystal manufacturing apparatus 100 according to Embodiment 1 of the present invention includes a crucible 10, a reaction vessel 20, a bellows 30, a support device 40, heating devices 50 and 60, a temperature sensor 51, 61, 71, 81, heating / cooling devices 70, 80, gas supply pipes 90, 200, valves 110, 150, pressure regulator 120, gas cylinders 130, 220, exhaust pipe 140, vacuum pump 160 A pressure sensor 170, a pipe 180, a thermocouple 190, a flow meter 210, a vibration applying device 230, a vertical mechanism 240, a vibration detecting device 250, a temperature control device 260, an alkali metal melt 280, 290.

  The crucible 10 has a substantially cylindrical shape and is made of boron nitride (BN) or SUS316L. The reaction vessel 20 is arranged around the crucible 10 with a predetermined distance from the crucible 10. That is, the reaction vessel 20 includes the crucible 10 inside. The reaction vessel 20 includes a main body portion 21, a lid portion 22, and a melt reservoir portion 23. Each of the main body 21, the lid 22, and the melt reservoir 23 is made of SUS316L, and the space between the main body 21 and the lid 22 is sealed with a metal O-ring. In addition, the melt reservoir 23 is provided on the bottom surface of the main body 21.

  The bellows 30 is connected to the reaction vessel 20 on the upper side of the crucible 10 in the gravity direction DR1. The support device 40 has a hollow cylindrical shape, and a part thereof is inserted into the space 24 in the reaction vessel 20 through the bellows 30.

  The heating device 50 is disposed so as to surround the outer peripheral surface 20 </ b> A of the reaction vessel 20. The heating device 60 is disposed to face the bottom surface 20B of the reaction vessel 20. The temperature sensors 51 and 61 are disposed close to the heating devices 50 and 60, respectively.

The heating / cooling device 70 is arranged so as to surround the melt reservoir 23, and the heating / cooling device 80 is arranged so as to surround the melt condensing unit 90 </ b> A in the gas supply pipe 90. The temperature sensors 71 and 81 are arranged close to the heating / cooling devices 70 and 80, respectively.

The gas supply pipe 90 includes gas introduction pipes 91 and 92. The gas supply pipe 91 has a melt condensing unit 90 </ b> A, one end connected to the bellows 30, and the other end connected to the valve 110. The gas supply pipe 92 has one end connected to the valve 110 and the other end connected to the gas cylinder 130 via the pressure regulator 120. The valve 110 is attached to the gas supply pipe 90 and connects the gas supply pipe 91 and the gas supply pipe 92.

  The pressure regulator 120 is attached to the gas supply pipe 90 (gas supply pipe 92) in the vicinity of the gas cylinder 130. The gas cylinder 130 is connected to a gas supply pipe 90 (gas supply pipe 92).

  One end of the exhaust pipe 140 is connected to the reaction vessel 20 via the valve 150, and the other end is connected to the vacuum pump 160. The valve 150 is attached to the exhaust pipe 140 in the vicinity of the reaction vessel 20. The vacuum pump 160 is connected to the other end of the exhaust pipe 140.

  The pressure sensor 170 is attached to the reaction vessel 20. The pipe 180 and the thermocouple 190 are inserted into the support device 40. The gas supply pipe 200 has one end connected to the pipe 180 and the other end connected to the gas cylinder 220 via the flow meter 210. The flow meter 210 is attached to the gas supply pipe 200 in the vicinity of the gas cylinder 220. The gas cylinder 220 is connected to the other end of the gas supply pipe 200. The vertical mechanism 240 is attached to the support device 40 on the upper side of the bellows 30.

The alkali metal melt 280 is made of a metal sodium (metal Na) melt and is held in the melt reservoir 23. The alkali metal melt 290 is made of a metal Na melt and is held in the melt condensing unit 90 </ b> A of the gas supply pipe 90.

  The crucible 10 holds a mixed melt 270 containing metal Na and metal gallium (metal Ga). The reaction vessel 20 covers the periphery of the crucible 10. The melt reservoir 23 stores the alkali metal melt 280. The bellows 30 holds the support device 40 and blocks the inside and outside of the reaction vessel 20. The bellows 30 expands and contracts in the gravity direction DR1 as the support device 40 moves in the gravity direction DR1. The support device 40 supports the seed crystal 5 made of a GaN crystal at one end inserted into the reaction vessel 20.

  The heating device 50 includes a heater and a current source. Then, the heating device 50 supplies a current to the heater with a current source in accordance with the control signal CTL1 from the temperature control device 260, and heats the crucible 10 and the reaction vessel 20 from the outer peripheral surface 20A of the reaction vessel 20 to the crystal growth temperature. The temperature sensor 51 detects the temperature T1 of the heater of the heating device 50, and outputs the detected temperature T1 to the temperature control device 260.

  The heating device 60 also includes a heater and a current source. Then, the heating device 60 causes the current to flow through the heater with a current source in accordance with the control signal CTL2 from the temperature control device 260, and heats the crucible 10 and the reaction vessel 20 from the bottom surface 20B of the reaction vessel 20 to the crystal growth temperature. The temperature sensor 61 detects the temperature T2 of the heater of the heating device 60 and outputs the detected temperature T2 to the temperature control device 260.

The heating / cooling device 70 includes a heating unit and a cooling unit. The heating unit includes a heater and a current source, and heats the melt reservoir 23 by causing a current to flow through the heater by the current source. The cooling unit cools the melt reservoir 23 by blowing cool air to the melt reservoir 23. The heating / cooling device 70 heats the temperature of the melt reservoir 23 to the evaporation suppression temperature or cools the temperature of the melt reservoir 23 to the condensation temperature in accordance with the control signal CTL3 from the temperature control device 260. Here, the evaporation suppression temperature is substantially equal to the vapor pressure P _Na of the alkali metal (metal Na) vaporized from the alkali metal melt 280 by the vapor pressure P _{Na-Ga of} the alkali metal (metal Na) evaporated from the mixed melt 270. Matching temperature. The condensation temperature is a temperature at which alkali metal vapor (metal Na vapor) accumulates as a metal melt.

  The temperature sensor 71 detects the temperature T3 of the heating part or the cooling part of the heating / cooling device 70, and outputs the detected temperature T3 to the temperature control device 260.

The heating / cooling device 80 has the same structure as the heating / cooling device 70. Then, the heater / cooler 80 sets the temperature of the melt condensing unit 90A to the condensing temperature or heats the temperature of the melt condensing unit 90A to the evaporation promoting temperature in accordance with the control signal CTL4 from the temperature control device 260. To do. Here, the evaporation promotion temperature is a temperature at which the alkali metal moves to another part by vapor transport.

  The temperature sensor 81 detects the temperature T4 of the heating unit or the cooling unit of the heating / cooling device 80, and outputs the detected temperature T4 to the temperature control device 260.

  The gas supply pipe 90 supplies nitrogen gas supplied from the gas cylinder 130 via the pressure regulator 120 into the reaction vessel 20 via the alkali metal melt 290. The valve 110 supplies nitrogen gas in the gas supply pipe 90 into the reaction vessel 20 or stops supply of nitrogen gas into the reaction vessel 20. The valve 110 separates the gas supply pipe 90 into the gas supply pipes 91 and 92 or connects the gas supply pipes 91 and 92 to each other. The pressure regulator 120 supplies nitrogen gas from the gas cylinder 130 to the gas supply pipe 90 at a predetermined pressure.

  The gas cylinder 130 holds nitrogen gas. The exhaust pipe 140 allows the gas in the reaction vessel 20 to pass through the vacuum pump 160. The valve 150 spatially connects the inside of the reaction vessel 20 and the exhaust pipe 140 or spatially blocks the inside of the reaction vessel 20 and the exhaust pipe 140. The vacuum pump 160 evacuates the reaction vessel 20 through the exhaust pipe 140 and the valve 150.

  The pressure sensor 170 detects the pressure in the reaction vessel 20. The pipe 180 cools the seed crystal 5 by releasing the nitrogen gas supplied from the gas supply pipe 200 into the support device 40 from one end. The thermocouple 190 detects the temperature T5 of the seed crystal 5 and outputs the detected temperature T5 to the temperature control device 260. Note that the nitrogen gas released into the support device 40 is released outside the crystal manufacturing apparatus 100 through an opening (not shown) of the support device 40.

  The gas supply pipe 200 supplies the nitrogen gas supplied from the gas cylinder 220 via the flow meter 210 to the pipe 180. The flow meter 210 adjusts the flow rate of the nitrogen gas supplied from the gas cylinder 220 in accordance with the control signal CTL5 from the temperature control device 260 and supplies it to the gas supply pipe 200. The gas cylinder 220 holds nitrogen gas.

  The vibration applying device 230 is made of, for example, a piezoelectric element, and applies vibration having a predetermined frequency to the support device 40. The vertical mechanism 240 moves the support device 40 up and down so that the seed crystal 5 comes into contact with the gas-liquid interface 2 between the space 24 and the mixed melt 270 by a method described later in accordance with the vibration detection signal BDS from the vibration detection device 250. To do.

  The vibration detection device 250 includes, for example, an acceleration pickup, detects vibration of the support device 40, and outputs a vibration detection signal BDS indicating the vibration of the support device 40 to the vertical mechanism 240.

The temperature control device 260 receives the temperatures T1 to T5 from the temperature sensors 51, 61, 71, 81 and the thermocouple 190, respectively, and generates control signals CTL1 to CTL5 based on the received temperatures T1 to T5. More specifically, the temperature control device 260 generates a control signal CTL1 for heating the crucible 10 and the reaction vessel 20 to the crystal growth temperature based on the temperature T1 from the temperature sensor 51, and outputs the control signal CTL1 from the temperature sensor 61. Based on the temperature T2, a control signal CTL2 for heating the crucible 10 and the reaction vessel 20 to the crystal growth temperature is generated. Further, the temperature control device 260 generates a control signal CTL3 for controlling the temperature of the melt reservoir 23 to the evaporation suppression temperature Tevc based on the temperature T3 from the temperature sensor 71 or the melt reservoir 23 A control signal CTL3 for controlling the temperature to the condensation temperature Tcoh is generated. Further, the temperature control device 260 generates a control signal CTL4 for controlling the temperature of the melt condensing unit 90A to the condensing temperature Tcoh based on the temperature T4 from the temperature sensor 81, or the temperature of the melt condensing unit 90A. A control signal CTL4 for controlling the temperature to the evaporation promotion temperature Tev is generated. Furthermore, the temperature control device 260 generates a control signal CTL5 for flowing nitrogen gas having a flow rate that sets the temperature T5 of the seed crystal 5 to a temperature lower than the crystal growth temperature, based on the temperature T5 from the thermocouple 190. To do.

  Then, the temperature control device 260 outputs the generated control signals CTL1 and CTL2 to the heating devices 50 and 60, outputs the control signals CTL3 and CTL4 to the heating / coolers 70 and 80, respectively, and outputs the control signal CTL5 as a flow rate. Output to total 210.

  FIG. 2 is an enlarged view of the support device 40, the pipe 180, and the thermocouple 190 shown in FIG. Referring to FIG. 2, support device 40 includes a cylindrical member 41 and fixing members 42 and 43. The cylindrical member 41 has a substantially circular cross-sectional shape. The fixing member 42 has a substantially L-shaped cross-sectional shape, and is fixed to the outer peripheral surface 41 </ b> A and the bottom surface 41 </ b> B of the cylindrical member 41 on the one end 411 side of the cylindrical member 41. The fixing member 43 has a substantially L-shaped cross-sectional shape, and the outer peripheral surface 41 </ b> A and the bottom surface 41 </ b> B of the cylindrical member 41 are arranged symmetrically with the fixing member 42 on the one end 411 side of the cylindrical member 41. Fixed to. As a result, a space 44 is formed in a region surrounded by the tubular member 41 and the fixing members 42 and 43.

  The pipe 180 has a substantially circular cross-sectional shape and is disposed inside the tubular member 41. In this case, the bottom surface 180 </ b> A of the pipe 180 is disposed so as to face the bottom surface 41 </ b> B of the tubular member 41. A plurality of holes 181 are formed in the bottom surface 180 </ b> A of the pipe 180. Nitrogen gas supplied into the pipe 180 is blown to the bottom surface 41 </ b> B of the tubular member 41 through the plurality of holes 181.

  The thermocouple 190 is disposed inside the tubular member 41 so that one end 190A is in contact with the bottom surface 41B of the tubular member 41 (see FIG. 2A).

  The seed crystal 5 has a shape that fits into the space 44 and is supported by the support device 40 by fitting into the space 44. In this case, the seed crystal 5 is in contact with the bottom surface 41B of the cylindrical member 41 (see FIG. 2B).

  Therefore, the thermal conductivity between the seed crystal 5 and the cylindrical member 41 is increased. As a result, the temperature T5 of the seed crystal 5 can be detected by the thermocouple 190, and the seed crystal 5 can be easily cooled by the nitrogen gas blown from the pipe 180 to the bottom surface 41B of the cylindrical member 41. In the first embodiment, the seed crystal itself has a shape that can be fitted to the support device 40 like the seed crystal 5. However, the seed crystal 5 has the shape of the seed crystal 5 as long as it is in contact with the support device 40. A hexagonal columnar seed crystal may be held via an adapter.

  FIG. 3 is a schematic diagram showing the configuration of the vertical mechanism 240 shown in FIG. Referring to FIG. 3, the vertical mechanism 240 includes an uneven member 241, a gear 242, a shaft member 243, a motor 244, and a control unit 245.

  The concavo-convex member 241 has a substantially triangular cross-sectional shape and is fixed to the outer peripheral surface 41 </ b> A of the tubular member 41. The gear 242 is fixed to one end of the shaft member 243 and meshes with the concavo-convex member 241. The shaft member 243 has one end connected to the gear 242 and the other end connected to a shaft (not shown) of the motor 244.

  The motor 244 rotates the gear 242 in the direction of the arrow 246 or 247 according to the control from the control unit 245. Based on the vibration detection signal BDS from the vibration detection device 250, the control unit 245 controls the motor 244 to rotate the gear 242 in the direction of the arrow 246 or 247.

  If the gear 242 rotates in the direction of the arrow 246, the support device 40 moves upward in the direction of gravity DR1, and if the gear 242 rotates in the direction of the arrow 247, the support device 40 moves downward in the direction of gravity DR1. Move to.

  Therefore, rotating the gear 242 in the direction of the arrow 246 or 247 corresponds to moving the support device 40 up and down in the gravity direction DR1. The length of the concavo-convex member 241 in the gravitational direction DR1 is a length corresponding to the distance that the support device 40 moves the seed crystal 5 up and down.

  FIG. 4 is a timing chart of the vibration detection signal BDS. Referring to FIG. 4, vibration detection signal BDS detected by vibration detection device 250 includes signal component SS1 when seed crystal 5 is not in contact with mixed melt 270, and seed crystal 5 is mixed with mixed melt 270. When in contact, it consists of the signal component SS2, and when the seed crystal 5 is immersed in the mixed melt 270, it consists of the signal component SS3.

  When the seed crystal 5 is not in contact with the mixed melt 270, the seed crystal 5 vibrates greatly due to the vibration applied by the vibration applying device 230. Therefore, the vibration detection signal BDS is generated from the signal component SS1 having a relatively large amplitude. Become. On the other hand, when the seed crystal 5 is in contact with the mixed melt 270, the seed crystal 5 cannot vibrate greatly due to the viscosity of the mixed melt 270 even when vibration is applied from the vibration applying device 230. Therefore, the vibration detection signal BDS is The signal component SS2 has a relatively small amplitude. Further, when the seed crystal 5 is immersed in the mixed melt 270, the seed crystal 5 is more difficult to vibrate due to the viscosity of the mixed melt 270 even when vibration is applied from the vibration applying device 230. The signal BDS includes a signal component SS3 having an amplitude smaller than that of the signal component SS2.

  Referring to FIG. 3 again, when control unit 245 receives vibration detection signal BDS from vibration detection device 250, control unit 245 detects the signal component of vibration detection signal BDS. Then, when the detected signal component is the signal component SS1, the control unit 245 moves the motor 40 so that the support device 40 is lowered in the gravity direction DR1 until the signal component of the vibration detection signal BDS becomes the signal component SS2 or SS3. 244 is controlled.

  More specifically, the control unit 245 controls the motor 244 to rotate the gear 242 in the direction of the arrow 247, and the motor 244 moves the gear 242 through the shaft member 243 according to the control from the control unit 245. Rotate in the direction of 247. Thereby, the support device 40 moves downward in the gravity direction DR1.

  Then, the control unit 245 controls the motor 244 to stop the rotation of the gear 242 when the signal component of the vibration detection signal BDS received from the vibration detection device 250 is switched from the signal component SS1 to the signal component SS2 or SS3. The motor 244 stops the rotation of the gear 242 according to the control from the control unit 245. As a result, the support device 40 stops moving and holds the seed crystal 5 at the gas-liquid interface 2 or holds the seed crystal 5 in the mixed melt 270. On the other hand, the control unit 245 controls the motor 244 to stop the movement of the support device 40 when the vibration detection signal BDS including the signal component SS2 or SS3 is received from the vibration detection device 250.

  As described above, the vertical mechanism 240 is based on the vibration detection signal BDS detected by the vibration detection device 250 so that the seed crystal 5 comes into contact with the mixed melt 270 or the seed crystal 5 is immersed in the mixed melt 270. In this way, the support device 40 is moved in the gravity direction DR1.

FIG. 5 is a timing chart of the temperatures of the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A shown in FIG. FIG. 6 is a schematic diagram showing a state change in the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A between the timings t1 and t3 shown in FIG. Further, FIG. 7 is a schematic diagram showing the state in the crucible 10 and the reaction vessel 20 at the timing t3 shown in FIG. Further, FIG. 8 is a diagram showing the relationship between the temperature of the seed crystal 5 and the flow rate of nitrogen gas.

In FIG. 5, a straight line k1 indicates the temperature of the crucible 10 and the reaction vessel 20, a curved line k2 and a straight line k3 indicate the temperature of the seed crystal 5, a curved line k4 indicates the temperature of the melt reservoir 23, A curve k5 indicates the temperature of the melt condensing unit 90A.

Referring to FIG. 5, heating devices 50 and 60 heat crucible 10 and reaction vessel 20 so that the temperature rises according to straight line k1 and is maintained at 800 ° C. during the period up to timing t5. Further, the heater / cooler 70 heats the melt reservoir 23 so that the temperature rises according to the curve k4 and is maintained at the evaporation suppression temperature Tevc during the period up to the timing t5. Further, the heating / cooling device 80 heats the melt condensing unit 90A so that the temperature rises according to the curve k5 and is maintained at the condensing temperature Tcoh during the period up to timing t5.

When the heating devices 50, 60 start to heat the crucible 10 and the reaction vessel 20, there are metal Na6 and metal Ga7 in the crucible 10, and the heating / cooling unit 70 begins to heat the melt reservoir 23, Further, when the heating / cooling unit 80 starts to heat the melt condensing unit 90A, metal Na6 is present in the melt reservoir 23, and metal Na is not present in the melt condensing unit 90A (FIG. 6). (See (a)).

  When the temperature of the crucible 10 and the reaction vessel 20 reaches 98 ° C. at the timing t1, the metal Na 6 in the crucible 10 is melted and mixed with the metal Ga 7 already melted at about 30 ° C. Thereafter, an intermetallic compound of Ga and Na is generated, and this intermetallic compound becomes the mixed melt 270 in the crucible 10 at a temperature of 560 ° C. or higher. And the temperature of the crucible 10 and the reaction container 20 reaches 800 degreeC in the timing t3.

When the temperature of the melt reservoir 23 reaches 98 ° C. at timing t 2, the metal Na 6 in the melt reservoir 23 is melted and an alkali metal melt 280 is generated in the melt reservoir 23. Thereafter, the temperature of the melt reservoir 23 reaches the evaporation suppression temperature Tevc at timing t3. Further, the temperature of the melt condensing unit 90A reaches the condensing temperature Tcoh at the timing t3.

Then, in the process in which the crucible 10 and the reaction vessel 20 are heated to 800 ° C. and the melt reservoir 23 is heated to the evaporation suppression temperature Tevc, the vapor pressure P _Na of the metal Na evaporated from the alkali metal melt 280 gradually increases. The vapor pressure P _{Na-Ga of} the metal Na evaporating from the mixed melt 270 gradually increases. Then, the metal Na evaporated from the melt mixture 270 and / or the alkali metal melt 280, the crucible 10, the melt condensation held in the condensation temperature Tcoh is lower than the temperature of the reaction vessel 20 and the melt reservoir 23 Condensed to part 90A. As a result, an alkali metal melt 290 is generated in the melt condensing unit 90A.

At timing t3, the vapor pressure P _Na-Ga of the alkali metal evaporated from the mixed melt 270 substantially matches the vapor pressure P _Na of the alkali metal evaporated from the alkali metal melt 280. That is, the evaporation of the metal Na from the mixed melt 270 and the evaporation of the metal Na from the alkali metal melt 280 are substantially equilibrated (see FIG. 6B).

  Therefore, the vapor phase transport of metal Na from the mixed melt 270 to the alkali metal melt 280 and the vapor phase transport of metal Na from the alkali metal melt 280 to the mixed melt 270 are substantially in equilibrium. The movement of the metal Na is stopped between the mixed melt 270 and the alkali metal melt 280. As a result, fluctuations in the mixing ratio of metal Na and metal Ga in mixed melt 270 due to evaporation of metal Na from mixed melt 270 and alkali metal melt 280 are suppressed.

At this time, if the temperature of the melt condensing unit 90A is equal to or higher than the melting point of the metal Na and the temperature at which the Na does not substantially evaporate, the diffusion of the metal Na toward the valve 110 in the gas supply pipe 90 is ignored. It is possible to further suppress the fluctuation of the mixing ratio of metal Na and metal Ga in the mixed melt 270. The temperature at which Na does not substantially evaporate is 200 to 300 ° C., for example. The vapor pressure of Na at 200 ° C. is about 1.8 × 10 ⁻² Pa, and the vapor pressure of Na at 300 ° C. is about 1.8 Pa. Although there is diffusion, fluctuations in the mixing ratio of metal Na and metal Ga in the mixed melt 270 can be suppressed. Therefore, the condensation temperature Tcoh is preferably set in a range of 200 to 300 ° C.

  The pressure of the nitrogen gas is adjusted by the pressure regulator 120, and the space 24 is filled through the gas supply pipe 90 (see FIG. 7).

  Further, at the timing t3 when the temperatures of the crucible 10 and the reaction vessel 20 reach 800 ° C., the vertical mechanism 240 moves the support device 40 up and down by the above-described method based on the vibration detection signal BDS from the vibration detection device 250, The crystal 5 is brought into contact with the mixed melt 270.

In a high temperature state where the temperature of the crucible 10 and the reaction vessel 20 is about 800 ° C., the nitrogen gas 4 in the space 24 is taken into the mixed melt 270 through the metal Na. In this case, the concentration of nitrogen or Ga _x N _y (x and y are real numbers) in the mixed melt 270 is the highest in the vicinity of the gas-liquid interface 2 between the space 24 and the mixed melt 270, so The growth starts from the seed crystal 5 in contact with the liquid interface 2. In the present invention, Ga _x N _{y is referred} to as “Group III nitride”, and the Ga _x N _y concentration is referred to as “Group III nitride concentration”.

  When nitrogen gas is not supplied into the pipe 180, the temperature T5 of the seed crystal 5 is 800 ° C., which is the same as the temperature of the mixed melt 270. In the present invention, the nitrogen in the mixed melt 270 near the seed crystal 5 is used. Alternatively, in order to increase the degree of supersaturation of the group III nitride, nitrogen gas is supplied into the pipe 180 to cool the seed crystal 5, and the temperature T 5 of the seed crystal 5 is made lower than the temperature of the mixed melt 270.

  More specifically, the temperature T5 of the seed crystal 5 is set to a temperature Ts1 lower than 800 ° C. according to the curve k2 after the timing t3. This temperature Ts1 is, for example, 790 ° C. A method for setting the temperature T5 of the seed crystal 5 to the temperature Ts1 will be described.

  In the temperature control device 260, the temperatures T1 and T2 received from the temperature sensors 51 and 61 are 800 + α ° C. (= the temperature of the heaters included in the heating devices 50 and 60 when the crucible 10 and the reaction vessel 20 are set to 800 ° C.). , The control signal CTL5 for flowing nitrogen gas having a flow rate that sets the temperature T5 of the seed crystal 5 to the temperature Ts1 is generated and output to the flow meter 210.

  Then, according to the control signal CTL5, the flow meter 210 causes nitrogen gas having a flow rate that sets the temperature T5 to the temperature Ts1 to flow into the pipe 180 from the gas cylinder 220 through the gas supply pipe 200. The temperature of the seed crystal 5 decreases from 800 ° C. in proportion to the flow rate of the nitrogen gas, and when the flow rate of the nitrogen gas reaches the flow rate fr1 (sccm), the temperature T5 of the seed crystal 5 is set to the temperature Ts1 ( (See FIG. 8).

  Therefore, the flow meter 210 allows the nitrogen gas having the flow rate fr1 to flow into the pipe 180. The nitrogen gas supplied into the pipe 180 is sprayed from the plurality of holes 181 of the pipe 180 to the bottom surface 41B of the tubular member 41.

  As a result, the seed crystal 5 is cooled via the bottom surface 41B of the cylindrical member 41, and the temperature T5 of the seed crystal 5 is lowered to the temperature Ts1 at the timing t4, and thereafter is held at the temperature Ts1 until the timing t5.

  Since the temperature T1 and T2 of the heaters of the heating devices 50 and 60 have a predetermined temperature difference α with the temperature of the mixed melt 270, the temperature control device 260 starts to decrease the temperature T5 of the seed crystal 5 from 800 ° C. The heating devices 50 and 60 are controlled by the control signals CTL1 and 2, respectively, so that the temperatures T1 and T2 received from the temperature sensors 51 and 61 are set to 800 + α ° C., respectively.

  In the present invention, preferably, the temperature T5 of the seed crystal 5 is controlled so as to decrease according to the straight line k3 after the timing t3. That is, the temperature T5 of the seed crystal 5 is decreased from 800 ° C. to the temperature Ts2 (<Ts1) between the timing t3 and the timing t5. In this case, the flow meter 210 increases the flow rate of nitrogen gas flowing into the pipe 180 from 0 to the flow rate fr2 (> fr1) according to the straight line k6 based on the control signal CTL5 from the temperature control device 260. When the flow rate of the nitrogen gas becomes the flow rate fr2, the temperature T5 of the seed crystal 5 is set to a temperature Ts2 that is lower than the temperature Ts1. And temperature Ts2 is 750 degreeC, for example.

  In this way, by gradually increasing the difference between the temperature (= 800 ° C.) of the mixed melt 270 and the temperature T5 of the seed crystal 5, nitrogen or group III nitride in the mixed melt 270 near the seed crystal 5 is obtained. The degree of supersaturation of GaN gradually increases, and at least GaN crystal growth can be continued.

  When the GaN crystal is grown in the crystal manufacturing apparatus 100, the seed crystal 5 is composed of a GaN crystal that is crystal-grown without using the seed crystal 5 in the crystal manufacturing apparatus 100. FIG. 9 is a diagram showing the relationship between the nitrogen gas pressure and the crystal growth temperature when a GaN crystal is grown. In FIG. 9, the horizontal axis represents the crystal growth temperature, and the vertical axis represents the nitrogen gas pressure. In addition, the region REG1 is a region where the GaN crystal is dissolved, and in the region REG2, many nuclei are spontaneously generated on the bottom surface and the side surface in contact with the mixed melt 270 of the crucible 10, and the c-axis (<0001>) direction. The region REG3 is a region where the GaN crystal grows from the seed crystal.

  Therefore, when producing the seed crystal 5, a GaN crystal is grown using the nitrogen gas pressure and the crystal growth temperature in the region REG2. In this case, many nuclei are generated on the bottom and side walls in the crucible 10, and a columnar GaN crystal grown in the c-axis direction is manufactured.

  Then, the GaN crystal having the shape shown in FIG. 2 is cut out from the many grown GaN crystals to produce the seed crystal 5. Therefore, the protrusion 5A (see FIG. 2B) of the seed crystal 5 is made of a GaN crystal grown in the c-axis (<0001>) direction.

  The produced seed crystal 5 is fitted into the space 44 of the support device 40 by the method described above and fixed to the support device 40.

  Referring to FIG. 5 again, when the crystal growth of the GaN crystal ends at timing t5, the heating devices 50 and 60 stop heating the crucible 10 and the reaction vessel 20, and the temperatures of the crucible 10 and the reaction vessel 20 are The temperature decreases from 800 ° C. according to the curve k1, and the temperature T5 of the seed crystal 5 decreases from the temperature Ts1 (or the temperature Ts2).

On the other hand, the heating / cooling device 70 cools the melt reservoir 23 according to the curve k4, and the temperature of the melt reservoir 23 is maintained at the condensation temperature Tcoh from timing t6 to timing t7. The heating / cooling device 80 heats the melt condensing unit 90A according to the curve k5, and the melt condensing unit 90A is held at the evaporation promotion temperature Tev from timing t6 to timing t7. Here, the evaporation promotion temperature Tev is a temperature at which the alkali metal melt 290 moves from the melt condensing part 90A to another part by vapor transport.

From timing t6 to timing t7, the temperature of the melt reservoir 23 is maintained at the condensation temperature Tcoh, and the temperature of the melt condensing unit 90A is maintained at the evaporation promoting temperature Tev. As a result, the alkali metal melt 290 is Then, it evaporates and is vapor-phase transported to the melt reservoir 23. At timing t7, the alkali metal melt 290 does not exist in the melt condensing unit 90A. When the alkali metal melt 290 is vapor-phase transported from the melt condensing unit 90A to the melt reservoir 23, the valve 110 is closed, so that the vapor of the metal Na evaporated from the alkali metal melt 290 is pressurized. It does not diffuse toward the regulator 120 side.

At timing t7, when the vapor phase transport of the alkali metal melt 290 from the melt condensing part 90A to the melt reservoir 23 is completed, the heating / cooling device 70 cools the melt reservoir 23, and the heating / cooling device 80 cools the melt condensing unit 90A. As a result, the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A are cooled toward room temperature after the timing t7.

  FIG. 10 is a flowchart in the first embodiment for explaining a method of manufacturing a GaN crystal. Referring to FIG. 10, when a series of operations is started, gas supply pipe 90 is separated into gas supply pipes 91 and 92 by valve 110, and crucible 10 and reaction vessel 20 are put into a glove box filled with Ar gas. And a gas supply pipe 91 is inserted. Then, metal Na is put into the melt reservoir 23 of the reaction vessel 20 in an Ar gas atmosphere (step S1). The Ar gas is an Ar gas having a water content of 1 ppm or less and an oxygen content of 1 ppm or less (hereinafter the same). Thereafter, metal Na and metal Ga are put into the crucible 10 in an Ar gas atmosphere (step S2). In this case, metal Na and metal Ga are put into the crucible 10 at a mixing ratio of 5: 5. Then, a crucible 10 containing metal Na and metal Ga is placed in the reaction vessel 20.

  Thereafter, seed crystal 5 is placed on top of metal Na and metal Ga in crucible 10 in an Ar gas atmosphere (step S3). More specifically, by fitting the seed crystal 5 into a space 44 formed on the one end 411 side of the support device 40 (see FIG. 2B), the seed crystal 5 is placed in the metal in the crucible 10. Installed above Na and metal Ga.

  Subsequently, the crucible 10, the reaction vessel 20 and the gas supply pipe 91 are taken out from the glove box, and the crucible 10, the reaction vessel 20 and the gas supply are supplied in a state where the crucible 10, the reaction vessel 20 and the gas supply pipe 91 are filled with Ar gas. The tube 91 is set in the crystal manufacturing apparatus 100.

  The gas supply pipe 92 is connected to the valve 110, the valve 150 is opened with the valve 110 closed, and the Ar gas filled in the crucible 10, the reaction vessel 20 and the gas supply pipe 91 is exhausted by the vacuum pump 160. . The inside of the crucible 10, the reaction vessel 20, and the gas supply pipe 91 is evacuated to a predetermined pressure (0.133 Pa or less) by the vacuum pump 160, and then the valve 150 is closed and the valve 110 is opened to supply nitrogen gas from the gas cylinder 130. The crucible 10 and the reaction vessel 20 are filled through the tube 90. In this case, nitrogen gas is supplied into the crucible 10 and the reaction container 20 by the pressure regulator 120 so that the pressure in the crucible 10 and the reaction container 20 is about 0.1 MPa.

  When the pressure in the reaction vessel 20 detected by the pressure sensor 170 reaches about 0.1 MPa, the valve 110 is closed, the valve 150 is opened, and the vacuum pump 160 fills the crucible 10, the reaction vessel 20, and the gas supply pipe 91. Exhausted nitrogen gas. Also in this case, the vacuum pump 160 evacuates the crucible 10, the reaction vessel 20, and the gas supply pipe 91 to a predetermined pressure (0.133 Pa or less).

  The evacuation of the crucible 10, the reaction vessel 20 and the gas supply pipe 91 and the filling of the nitrogen gas into the crucible 10, the reaction vessel 20 and the gas supply pipe 91 are repeated several times.

  Thereafter, the inside of the crucible 10, the reaction vessel 20 and the gas supply pipe 91 is evacuated to a predetermined pressure by the vacuum pump 160, the valve 150 is closed, the valve 110 is opened, and the pressure regulator 120 is used to close the crucible 10, the reaction vessel 20 and Nitrogen gas is filled into the crucible 10, the reaction vessel 20, and the gas supply pipe 91 so that the pressure in the gas supply pipe 91 is in the range of 1.01 MPa (step S4).

Thereafter, the crucible 10 and the reaction vessel 20 are heated to 800 ° C. by the heating devices 50 and 60 (step S5), and the vapor pressure P _{Na of} metal Na evaporating from the alkali metal melt 280 is mixed and melted by the heating / cooling device 70. The temperature of the alkali metal melt 280 is controlled to an evaporation suppression temperature Tvc that substantially matches the vapor pressure PNa _-Ga of the metal Na evaporating from the liquid 270 (step S6).

Moreover, the temperature of the region (= melt condensing part 90A) near the space 24 of the crucible 10 and the reaction vessel 20 in the gas supply pipe 90 for supplying nitrogen gas is controlled by the heating / cooling device 80 to the condensation temperature Tcoh. (Step S7).

  In this case, since the melting point of the metal Na held in the melt reservoir 23 is about 98 ° C., the metal Na is melted in the process where the melt reservoir 23 is heated to the evaporation suppression temperature Tevc, and the alkali metal melt 280 is melted. Become. And the gas-liquid interface 1 generate | occur | produces (refer FIG. 1). The gas-liquid interface 1 is located at the interface between the alkali metal melt 280 and the space 24 in the reaction vessel 20.

  Further, in the process in which the crucible 10 and the reaction vessel 20 are heated to 800 ° C., the metal Na and metal Ga in the crucible 10 also become liquid, and a mixed melt 270 of metal Na and metal Ga is generated in the crucible 10. .

Then, as the temperature of the melt reservoir 23 approaches the evaporation suppression temperature Tevc and the temperature of the crucible 10 approaches 800 ° C., the vapor pressure P _Na of the metal Na evaporating from the alkali metal melt 280 and the mixed melt 270 are mixed. The vapor pressure P _Na-Ga of the metal Na evaporating from the gas gradually increases, and the metal Na vapor existing in the space 24 in the reaction vessel 20 increases. Part of the metal Na vapor present in the space 24 diffuses into the melt condensation section 90A is lower than the temperature of the crucible 10 and the reaction vessel 20, to condense the alkali metal melt 290 in the melt condensation part 90A. Then, the vapor pressure _{P Na} is substantially equal to the vapor pressure _{P Na-Ga.}

  Thereafter, the vertical mechanism 240 brings the seed crystal 5 into contact with the mixed melt 270 by the method described above (step S8). In a high temperature state where the temperature of the crucible 10 and the reaction vessel 20 is about 800 ° C., the nitrogen gas in the space 24 is taken into the mixed melt 270 through the metal Na, so that the GaN crystal is transformed from the seed crystal 5. Begins to grow. At this time, the temperatures of the crucible 10 and the reaction vessel 20 and the nitrogen gas pressure in the reaction vessel 20 are in the region REG3 shown in FIG.

Thereafter, the temperature of the crucible 10 and the reaction vessel 20 is maintained at 800 ° C. for a predetermined time (several tens to several hundreds of hours), and the temperature of the alkali metal melt 280 in the melt reservoir 23 is maintained at the evaporation suppression temperature Tevc. Then, the temperature of the melt condensing unit 90A is maintained at the condensing temperature Tcoh (step S9). Further, the temperature T5 of the seed crystal 5 is set to a temperature Ts1 or Ts2 lower than the temperature (= 800 ° C.) of the mixed melt 270 by the above-described method (step S10).

  As the growth of the GaN crystal proceeds, the nitrogen gas in the space 24 is consumed and the nitrogen gas in the space 24 decreases. Then, the pressure P1 in the space 24 becomes lower than the pressure P2 in the gas supply pipe 90 (P1 <P2), a differential pressure is generated between the space 24 and the gas supply pipe 90, and the gas supply pipe 91 The nitrogen gas is supplied into the space 24 through the alkali metal melt 290 (= metal Na melt). That is, nitrogen gas is supplied to the crucible 10 and the space 24 of the reaction vessel 20 (step S11). At this time, even if the alkali metal melt 290 is present by blocking the entire axial cross section of the gas supply pipe 91 (exists so as to partition the valve 110 side and the reaction vessel 20 side), the alkali metal melt 290 is liquid. Therefore, the nitrogen gas is introduced into the space 24 in the reaction vessel 20 so as to push the alkali metal melt 290 by the differential pressure of the nitrogen gas.

  Thereafter, the seed crystal 5 is moved by the above-described method so that the seed crystal 5 comes into contact with the mixed melt 270 (step S12). As a result, a large GaN crystal grows.

  When a predetermined time has elapsed, the temperatures of the crucible 10 and the reaction vessel 20 are lowered (step S13), and the production of the GaN crystal is completed.

In addition, after step S13, the temperature of the melt reservoir 23 is maintained at the condensation temperature Tcoh, and the temperature of the melt condensing unit 90A is maintained at the evaporation promotion temperature Tev. As a result, the alkali metal melt 290 is moved from the melt condensing unit 90 </ b> A to the melt reservoir 23 by vapor transport. Then, the next GaN crystal is manufactured according to the flowchart shown in FIG.

Thus, the raw material for manufacturing the next GaN crystal in a state where the alkali metal melt 290 accumulated in the melt condensing part 90A in the gas supply pipe 90 is moved to the melt reservoir 23 in the reaction vessel 20. Is charged.

As described above, in the present invention, by substantially matching the vapor pressure _{P Na-Ga} of the metal Na to evaporate the vapor pressure _{P Na} metal Na evaporated from the alkali metal melt 280 from the melt mixture 270 is GaN crystal Manufactured. Then, it is substantially matched to the vapor pressure _{P Na} in vapor pressure _{P Na-Ga} is heated / cooler 70 is achieved by heating the melt reservoir 23 to the evaporation suppression temperature TEVC.

  Therefore, as described above, the movement of the metal Na between the alkali metal melt 280 and the mixed melt 270 apparently disappears, and the fluctuation of the mixing ratio of the metal Na and the metal Ga in the mixed melt 270 does not occur. It is suppressed. As a result, it is possible to manufacture a GaN crystal while suppressing fluctuations in the mixing ratio of metal Na and metal Ga.

Further, the melt condensing unit 90A of the gas supply pipe 90 that supplies nitrogen gas into the reaction vessel 20 is maintained at the condensation temperature Tcoh where the alkali metal vapor is accumulated as the alkali metal melt, and the GaN crystal is manufactured. Then, keeping the temperature of the melt condensation part 90A to the condensation temperature Tcoh, the heating / cooling device 80 is realized by a melt condensation section 90A controls the condensation temperature Tcoh (heating / cooling).

Therefore, even if the metal Na vapor diffuses from the space 24 in the reaction vessel 20 into the gas supply pipe 90, the diffused metal Na accumulates in the melt condensing unit 90 </ b> A as the alkali metal melt 290. And the spreading | diffusion to the exterior of the metal Na which exists in the space 24 in the reaction container 20 is suppressed. As a result, the fluctuation of the mixing ratio of metal Na and metal Ga in the mixed melt 270 is suppressed, and the GaN crystal can be manufactured while suppressing the fluctuation of the mixing ratio of metal Na and metal Ga.

In the above, the alkali metal melts 280 and 290 are held in the melt reservoir 23 and the melt condensing unit 90A, respectively, without adding metal Na to the melt condensing unit 90A in the gas supply pipe 90 to crystallize the GaN crystal. In the first embodiment, the growth is described, but the present invention is not limited to this. Metal Na is charged into both the melt reservoir 23 and the melt condensing unit 90A, and the alkali metal melts 280 and 290 are respectively melted. You may make it hold | maintain in the reservoir part 23 and the melt condensing part 90A.

FIG. 11 is another schematic diagram showing a state change in the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A between the timings t1 and t3 shown in FIG. Referring to FIG. 11, metal Na6 is charged into both melt reservoir 23 and melt condensing unit 90A (see FIG. 11 (a)). The heating devices 50 and 60 heat the crucible 10 and the reaction vessel 20 to 800 ° C., the heating / cooling device 70 heats the melt reservoir 23 to the evaporation suppression temperature Tevc, and the heating / cooling device 80 The melt condensing unit 90A is heated to the condensing temperature Tcoh. As a result, the metal Na6 charged in the melt reservoir 23 is melted to become the alkali metal melt 280, and the metal Na6 charged in the melt condensing portion 90A is melted to become the alkali metal melt 290, and the crucible. The metal Na 6 and the metal Ga 7 charged in 10 are melted to become a mixed melt 270. Then, the crystal growth of a GaN crystal in a state that substantially corresponds to the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} metal Na evaporated from the alkali metal melt 280 is evaporated from the melt mixture 270 is performed.

FIG. 12 is another flowchart in the first embodiment for explaining a method of manufacturing a GaN crystal. When the metal Na6 is charged into both the melt reservoir 23 and the melt condensing unit 90A, crystal growth of the GaN crystal is performed according to the flowchart shown in FIG.

  The flowchart shown in FIG. 12 is the same as the flowchart shown in FIG. 10 except that step S1 of the flowchart shown in FIG. 10 is replaced with step S1A.

Referring to FIG. 12, when a series of operations is started, gas supply pipe 90 is separated into gas supply pipes 91 and 92 by valve 110, and crucible 10 and reaction vessel 20 are put into a glove box filled with Ar gas. And a gas supply pipe 91 is inserted. Then, in the Ar gas atmosphere, metal Na is put into the melt reservoir 23 of the reaction vessel 20 and the melt condensing unit 90A in the gas supply pipe 91 (step S1A). In addition, when charging the metal Na6 into the melt condensing unit 90A, the valve 110 is opened in the Ar gas atmosphere, the metal Na6 is charged into the melt condensing unit 90A from the valve 110 side, and then the valve 110 is closed.

  Then, Steps S2 to S13 described above are sequentially performed, and the crystal growth of the GaN crystal is completed.

Even when the GaN crystal is manufactured according to the flowchart shown in FIG. 12, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing part 90A is obtained by the above-described method. It is moved to the melt reservoir 23 by vapor transport.

By preparing the metal Na6 in both the melt reservoir 23 and the melt condensing unit 90A, the mixed melt 270 is heated to 800 ° C., and the alkali metal melt 280 is heated to the evaporation suppression temperature Tevc. In the process, the amount of metal Na evaporated from the mixed melt 270 and / or the alkali metal melt 280 and accumulated as the alkali metal melt 290 in the melt condensing part 90A can be reduced, and the metal in the mixed melt 270 can be reduced. Variations in the mixing ratio of Na and metal Ga can be further suppressed.

Further, in the above, metal Na is charged only in the melt reservoir 23 of the reaction vessel 20 or in both the melt reservoir 23 and the melt condensing unit 90A, and the alkali metal melts 280 and 290 are respectively stored in the melt reservoirs. 23 and the melt condensing unit 90A are described above. However, in the first embodiment, the present invention is not limited to this, and only the melt condensing unit 90A is charged with metal Na so that the alkali metal melts 280 and 290 are respectively melted. You may make it hold | maintain in the reservoir part 23 and the melt condensing part 90A.

FIG. 13 is still another schematic diagram showing a state change in the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A between the timings t1 and t3 shown in FIG. Referring to FIG. 13, metal Na6 for generating alkali metal melt 290 is charged only into melt condensing unit 90A (see FIG. 13A). The heating devices 50 and 60 heat the crucible 10 and the reaction vessel 20 to 800 ° C., the heating / cooling device 70 heats the melt reservoir 23 to the evaporation suppression temperature Tevc, and the heating / cooling device 80 The melt condensing unit 90A is heated to the condensing temperature Tcoh. As a result, the metal Na6 charged in the melt condensing unit 90A is melted to become the alkali metal melt 290, and the metal Na6 and metal Ga7 charged in the crucible 10 are melted to become the mixed melt 270. As the temperature of the crucible 10 approaches 800 ° C., the vapor pressure P _Na—Ga of the metal Na evaporating from the mixed melt 270 gradually increases, and the metal Na evaporated from the mixed melt 270 becomes the melt reservoir 23. In the form of an alkali metal melt 280. Thereafter, until substantially corresponds to the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} metal Na evaporated from the alkali metal melt 280 is evaporated from the melt mixture 270, the metal Na is mixed melt by vapor transport The liquid 270 moves to the alkali metal melt 280. When substantially match the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} metal Na evaporated from the alkali metal melt 280 is evaporated from the melt mixture 270, the alkali metal melt from the melt mixture 270 of metal Na The vapor phase transport to the liquid 280 is stopped, and crystal growth of the GaN crystal is performed in this state.

FIG. 14 is still another flowchart in the first embodiment for explaining a method of manufacturing a GaN crystal. When the metal Na6 is charged only in the melt condensing unit 90A, the crystal growth of the GaN crystal is performed according to the flowchart shown in FIG.

  The flowchart shown in FIG. 14 is the same as the flowchart shown in FIG. 10 except that step S1 of the flowchart shown in FIG. 10 is replaced with step S1B.

Referring to FIG. 14, when a series of operations is started, gas supply pipe 90 is separated into gas supply pipes 91 and 92 by valve 110, and crucible 10 and reaction vessel 20 are put into a glove box filled with Ar gas. And a gas supply pipe 91 is inserted. And metal Na is put into the melt condensing part 90A in the gas supply pipe 91 in Ar gas atmosphere (step S1B). In addition, when charging the metal Na6 into the melt condensing unit 90A, the valve 110 is opened in the Ar gas atmosphere, the metal Na6 is charged into the melt condensing unit 90A from the valve 110 side, and then the valve 110 is closed.

  Then, Steps S2 to S13 described above are sequentially performed, and the crystal growth of the GaN crystal is completed.

Even when the GaN crystal is manufactured according to the flowchart shown in FIG. 14, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 collected in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

  The crystal manufacturing apparatus according to Embodiment 1 may be a crystal manufacturing apparatus 100A shown in FIG. FIG. 15 is another schematic cross-sectional view of the crystal manufacturing apparatus according to the first embodiment. Referring to FIG. 15, crystal manufacturing apparatus 100A replaces reaction vessel 20 of crystal manufacturing apparatus 100 shown in FIG. 1 with reaction vessel 300, replaces heating / cooling device 70 with heating / cooling device 70A, and provides temperature sensor 71. Instead of the temperature sensor 71A, the temperature control device 260 is replaced with the temperature control device 260A, and a pipe 310, a container 320, a heating device 330, and a temperature sensor 331 are added. The rest is the same as the crystal manufacturing apparatus 100.

  The reaction vessel 300 is the same as the reaction vessel 20 except that the main body portion 21 of the reaction vessel 20 shown in FIG. The main body 301 is the same as the main body 21 except that the melt reservoir 23 of the main body 21 shown in FIG.

  In the crystal manufacturing apparatus 100 </ b> A, the heating device 50 is arranged so as to cover the periphery of the outer peripheral surface 300 </ b> A of the reaction vessel 300, and the heating device 60 is arranged to face the bottom surface 300 </ b> B of the reaction vessel 300.

  One end of the pipe 310 is connected to the reaction vessel 300. The container 320 is connected to the other end side of the pipe 310. The heating / cooling device 70 </ b> A is disposed to face the side surface and the bottom surface of the container 320. The temperature sensor 71A is disposed close to the heating / cooling device 70A. The heating device 330 is disposed to face the pipe 310. The temperature sensor 331 is disposed in the vicinity of the heating device 330.

The heating / cooling device 70A heats the container 320 to the evaporation suppression temperature Tecc or cools the container 320 to the condensation temperature Tcoh according to the control signal CTL3 from the temperature control device 260A. The temperature sensor 71A detects the temperature T3 of the heating part or the cooling part of the heating / cooling device 70A and outputs it to the temperature control device 260A.

  The pipe 310 communicates the space 24 of the reaction vessel 300 with the space in the vessel 320. The container 320 holds the alkali metal melt 280.

  The heating device 330 includes a heater and a current source. In response to a control signal CTL6 from the temperature control device 260A, a current is supplied to the heater by the current source to heat the pipe 310 to 800 ° C. (= crystal growth temperature). . The temperature sensor 331 detects the temperature T6 of the heater of the heating device 330, and outputs the detected temperature T6 to the temperature control device 260A. The temperature controller 260A receives the temperature T6 from the temperature sensor 331, generates a control signal CTL6 for setting the temperature of the pipe 310 to 800 ° C. (= crystal growth temperature) based on the received temperature T6, and heats it. Output to the device 330. The temperature control device 260A performs the same functions as the temperature control device 260 in other respects.

When crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100A, 1) metal Na for generating the alkali metal melt 280, 290 is charged only in the container 320, and 2) the alkali metal melt 280, 290 is generated. One of the following is used: charging metal Na into the melt condensing unit 90A and the container 320; 3) charging metal Na to generate the alkali metal melts 280 and 290 only into the melt condensing unit 90A.

When the above 1) is used, crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100A according to the flowchart shown in FIG. When the above 2) is used, GaN crystals are grown in the crystal manufacturing apparatus 100A according to the flowchart shown in FIG. Further, when the above 3) is used, crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100A according to the flowchart shown in FIG. When the GaN crystal is grown according to any one of the flowchart shown in FIG. 10, the flowchart shown in FIG. 12, and the flowchart shown in FIG. 14, the metal Na that evaporates from the alkali metal melt 280 held in the container 320. so as to be substantially coincident to the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} evaporates from the melt mixture 270, the heating / cooling device 70A heats the container 320 to the evaporation inhibitor temperature TEVC.

As described above, in the first embodiment, the alkali metal melt 280 having the vapor pressure P _Na that substantially matches the vapor pressure P _Na—Ga of the metal Na evaporated from the mixed melt 270 is held in the reaction vessel 300. It is not necessary to be carried out and may be held outside the reaction vessel 300. In this case, the pipe 310 communicating the space 24 of the reaction vessel 300 and the space of the vessel 320 is heated by the heating device 330 to a crystal growth temperature, generally a temperature at which the metal Na vapor is not condensed . When the temperature of the pipe 310 is set to a temperature at which the metal Na vapor is condensed , the metal Na in the space 24 is condensed on the inner wall of the pipe 310, and the evaporation of the metal Na from the mixed melt 270 increases and mixing. Since the fluctuation of the mixing ratio of metal Na and metal Ga in the melt 270 becomes large, in order to prevent this, the temperature of the pipe 310 is set to a temperature at which the metal Na vapor is not condensed .

In the case of producing a GaN crystal using the crystal production apparatus 100A, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 held in the melt condensing unit 90A is stored in the container 320 by the above-described method. Vaporized to the gas phase.

  Others are the same as the crystal manufacturing apparatus 100.

  In the above description, the GaN crystal is grown by bringing the seed crystal 5 into contact with the gas-liquid interface 2 between the mixed melt 270 and the space 24. However, the present invention is not limited to this, and the seed crystal is not limited thereto. 5 may be immersed in the mixed melt 270 to grow a GaN crystal. In this case, in step S8 of the flowchart shown in FIG. 10, the flowchart shown in FIG. 12, and the flowchart shown in FIG. 14, the seed crystal 5 is immersed in the mixed melt 270 by the up-and-down mechanism 240. Is moved by the vertical mechanism 240 so as to be immersed in the mixed melt 270.

In the above, the temperature of the alkali metal melt 280 held in the melt reservoir 23 of the reaction vessel 20 or the vessel 320 out of the two alkali metal melts 280 and 290 is controlled to the evaporation suppression temperature Tevc. Although it has been described that the GaN crystal is manufactured, the first embodiment is not limited to this, and the GaN crystal is manufactured by controlling the temperatures of the two alkali metal melts 280 and 290 to the evaporation suppression temperature Tevc. It may be. In this case, the heating / cooling device 80 sets the temperature of the melt condensing unit 90A to the evaporation suppression temperature Tev from the timing t3 to the timing t5 in accordance with the control signal CTL4 from the temperature control device 260 or 260A. Between t6 and timing t7, the temperature of the melt condensing unit 90A is set to the evaporation promotion temperature Tev.

  In the first embodiment, the heating / cooling devices 70 and 80 and the temperature control device 260 constitute “control means”.

  The heating / cooling device 70 constitutes a “first heating / cooling device”, and the heating / cooling device 80 constitutes a “second heating / cooling device”. The temperature control device 260 to be controlled constitutes a “control device”.

  Furthermore, the heating / cooling devices 70A and 80 and the temperature control device 260A constitute “control means”.

  Furthermore, the heating / cooling device 70A constitutes a “first heating / cooling device”, and the heating / cooling device 80 constitutes a “second heating / cooling device”, and the heating / cooling devices 70A, 80 are arranged. The temperature control device 260A to be controlled constitutes a “control device”.

  Further, the gas supply pipe 90 constitutes a “gas introduction pipe”, and the container 320 constitutes a “melt holding container”.

  Furthermore, the alkali metal melt 290 constitutes a “first alkali metal melt”, and the alkali metal melt 280 constitutes a “second alkali metal melt”.

  Furthermore, the gas supply pipe 90, the valve 110, the pressure regulator 120, and the gas cylinder 130 constitute a “gas supply device”.

  Further, the support device 40, the vibration applying device 230, the vertical mechanism 240 and the vibration detecting device 250 constitute a “holding unit” that holds the seed crystal 5.

[Embodiment 2]
FIG. 16 is a schematic cross-sectional view of the crystal manufacturing apparatus according to the second embodiment. Referring to FIG. 16, crystal manufacturing apparatus 100B according to the second embodiment is configured by replacing heating / cooling devices 70 and 80 of crystal manufacturing apparatus 100 shown in FIG. 1 with heating / cooling devices 70B and 80A, respectively. Others are the same as the crystal manufacturing apparatus 100.

The heating / cooling device 70B heats the melt reservoir 23 to the evaporation promoting temperature Tev or cools the melt reservoir 23 to the condensation temperature Tcoh. The heating / cooling device 80A heats the melt condensing unit 90A to the evaporation suppression temperature Tev, or heats the melt condensing unit 90A to the evaporation promoting temperature Tev.

FIG. 17 is a timing chart of the temperatures of the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A shown in FIG. Referring to FIG. 17, the temperature control of crucible 10 and reaction vessel 20 is performed according to curve k1 described above, and the temperature control of seed crystal 5 is performed according to curve k2 or straight line k3 described above.

In the crystal manufacturing apparatus 100B, the heating / cooling device 70B heats the melt reservoir 23 to the evaporation promoting temperature Tev at the timing t8 according to the curve k9, and then opens the melt reservoir 23 from the timing t8 to the timing t5. The evaporation promoting temperature Tev is maintained, and the melt reservoir 23 is cooled to the condensation temperature Tcoh from timing t6 to timing t7.

The crystal in the production apparatus 100B, a heating / cooling device 80A in accordance with the curve k8, the melt condensation section 90A is heated to the evaporation inhibitor temperature Tevc at timing t3, the period from timing t3 to timing t5, the melt condensation unit 90A is held at the evaporation suppression temperature Tvc, and the melt condensing unit 90A is heated to the evaporation promotion temperature Tev from timing t6 to timing t7.

FIG. 18 is a schematic diagram showing a state change in the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A between the timings t1 and t3 shown in FIG.

Referring to FIG. 18, when heating devices 50 and 60 begin to heat crucible 10 and reaction vessel 20, metal Na 6 and metal Ga 7 exist in crucible 10, and heating / cooling unit 70 B stores the melt. When the part 23 starts to be heated and the heating / cooling part 80A starts to heat the melt condensing part 90A, the melt reservoir 23 contains metal Na6, and the melt condensing part 90A has a metal Na is not present (see FIG. 18A).

  When the temperature of the crucible 10 and the reaction vessel 20 reaches 98 ° C. at the timing t1, the metal Na 6 in the crucible 10 is melted and mixed with the metal Ga 7 already melted at about 30 ° C. Thereafter, an intermetallic compound of Ga and Na is generated, and this intermetallic compound becomes the mixed melt 270 in the crucible 10 at a temperature of 560 ° C. or higher. And the temperature of the crucible 10 and the reaction container 20 reaches 800 degreeC in the timing t3.

When the temperature of the melt reservoir 23 reaches 98 ° C. or higher, the metal Na 6 in the melt reservoir 23 is melted and an alkali metal melt is generated in the melt reservoir 23. Thereafter, the temperature of the melt reservoir 23 reaches the evaporation promotion temperature Tev at the timing t8, and is maintained at the evaporation promotion temperature Tev from the timing t8 to the timing t3. Further, the temperature of the melt condensing unit 90A reaches the evaporation suppression temperature Tvc at the timing t3.

Then, during a period in which the temperature of the melt reservoir 23 is maintained at the evaporation promotion temperature Tev (a period from timing t8 to timing t3), the metal Na evaporates from the alkali metal melt generated in the melt reservoir 23. , the evaporated metal Na vapor condenses as the alkali metal melt 290 in the melt condensation section 90A of the gas supply pipe 90 is cold portion than the crucible 10 and the reaction vessel 20. At timing t3, all of the alkali metal melt generated in the melt reservoir 23 moves to the melt condensing unit 90A by vapor transport. At the timing t3, the temperature of the melt condensing unit 90A is set to the evaporation suppression temperature Tevc, so that the vapor pressure P _Na of the metal Na evaporating from the alkali metal melt 290 is the metal evaporating from the mixed melt 270. This substantially corresponds to the vapor pressure P _Na-Ga of _Na . That is, the evaporation of the metal Na from the mixed melt 270 and the evaporation of the metal Na from the alkali metal melt 290 are substantially balanced (see FIG. 18B).

  Therefore, the vapor phase transport of metal Na from the mixed melt 270 to the alkali metal melt 290 and the vapor phase transport of metal Na from the alkali metal melt 290 to the mixed melt 270 are substantially in equilibrium. The movement of metal Na is stopped between the mixed melt 270 and the alkali metal melt 290. As a result, fluctuations in the mixing ratio of metal Na and metal Ga in the mixed melt 270 due to evaporation of metal Na from the mixed melt 270 and the alkali metal melt 290 are suppressed.

  FIG. 19 is a flowchart in the second embodiment for explaining a GaN crystal manufacturing method. The flowchart shown in FIG. 19 is the same as the flowchart shown in FIG. 10 except that step S6, step S7, and step 9 in the flowchart shown in FIG. 10 are replaced with step S6A, step S7A, and step 9A, respectively. .

Referring to FIG. 19, when a series of operations are started, the above-described steps S1 to S5 are sequentially executed. After step S 5, the heating / cooling device 80 A evaporates from the mixed melt 270 the vapor pressure P _{Na of} metal Na that evaporates the temperature of the melt condensing unit 90 A of the gas supply pipe 90 from the alkali metal melt 290. Control is performed to an evaporation suppression temperature Tvc substantially equal to the vapor pressure PNa _-Ga of metal Na (step S6A).

Then, the heater / cooler 70B heats the melt reservoir 23 to the evaporation promotion temperature Tev (step S7A). As a result, the alkali metal melt generated in the melt reservoir 23 is evaporated and accumulated as an alkali metal melt 290 in the melt condensing part 90A in the gas supply pipe 90 by vapor transport. Then, the vapor pressure P _Na of metal Na evaporating from the alkali metal melt 290 is substantially in equilibrium with the vapor pressure P _{Na-Ga of} metal Na evaporating from the mixed melt 270.

Thereafter, step S8 described above is executed, and the crucible 10 and the reaction vessel 20 are held at 800 ° C. (= crystal growth temperature) for a predetermined time, and the melt reservoir 23 of the reaction vessel 20 is set to the evaporation promotion temperature Tev. The melt condensing unit 90A of the gas supply pipe 90 is held at the evaporation suppression temperature Tvc (step S9A).

  And step S10-step S13 mentioned above are performed sequentially, and a series of operation | movement is complete | finished.

Even when the GaN crystal is manufactured according to the flowchart shown in FIG. 19, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport. Alternatively, when the same crystal growth is performed next, the alkali metal melt 290 may be left as it is in the melt condensing unit 90A.

As described above, the vapor pressure P _Na of the metal Na evaporating from the alkali metal melt 290 held in the melt condensing part 90A in the gas supply pipe 90 for supplying nitrogen gas into the reaction vessel 20 and the mixed melt 270 are mixed. By substantially equilibrating the vapor pressure P _Na-Ga of the metal Na evaporating from the metal Na, the evaporation of the metal Na from the mixed melt 270 is substantially suppressed, and the metal Na and the metal Ga in the mixed melt 270 are The fluctuation of the mixing ratio can be suppressed.

In the above description, it has been described that the alkali metal melt 290 is held in the melt condensing unit 90A without adding metal Na to the melt condensing unit 90A in the gas supply pipe 90, and the GaN crystal is grown. in the second embodiment, not limited thereto, the alkali metal melt 290 may be held in the melt condensation section 90A were charged metal Na only in the melt condensation section 90A.

FIG. 20 is another schematic diagram showing a state change in the crucible 10, the reaction vessel 20, the melt reservoir 23, and the melt condensing unit 90A between the timings t1 and t3 shown in FIG. Referring to FIG. 20, metal Na6 for generating alkali metal melt 290 is charged only into melt condensing unit 90A (see FIG. 20 (a)). The heating devices 50 and 60 heat the crucible 10 and the reaction vessel 20 to 800 ° C., the heating / cooling device 70B heats the melt reservoir 23 to the evaporation promoting temperature Tev, and the heating / cooling device 80A The melt condensing unit 90A is heated to the evaporation suppression temperature Tvc. As a result, the metal Na6 charged in the melt condensing unit 90A is melted to become the alkali metal melt 290, and the metal Na6 and metal Ga7 charged in the crucible 10 are melted to become the mixed melt 270. Then, the crystal growth of a GaN crystal in a state that substantially corresponds to the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} metal Na evaporated from the alkali metal melt 290 is evaporated from the melt mixture 270 is performed. In this case, the alkali metal melt does not accumulate in the melt reservoir 23.

FIG. 21 is another flowchart in the second embodiment for explaining a method of manufacturing a GaN crystal. When the metal Na6 for generating the alkali metal melt 290 is charged only into the melt condensing unit 90A, the crystal growth of the GaN crystal is performed according to the flowchart shown in FIG.

  The flowchart shown in FIG. 21 is the same as the flowchart shown in FIG. 19 except that step S1 of the flowchart shown in FIG. 19 is replaced with step S1A.

Referring to FIG. 21, when a series of operations is started, gas supply pipe 90 is separated into gas supply pipes 91 and 92 by valve 110, and crucible 10 and reaction vessel 20 are put into a glove box filled with Ar gas. And a gas supply pipe 91 is inserted. And metal Na is put into the melt condensing part 90A in the gas supply pipe 91 in Ar gas atmosphere (step S1A). In addition, when charging the metal Na6 into the melt condensing unit 90A, the valve 110 is opened in the Ar gas atmosphere, the metal Na6 is charged into the melt condensing unit 90A from the valve 110 side, and then the valve 110 is closed.

  And step S2-5, S6A, S7A, S8, S9A, S10-S13 mentioned above are performed sequentially, and the crystal growth of a GaN crystal is complete | finished.

Even when the GaN crystal is manufactured in accordance with the flowchart shown in FIG. 21, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing part 90A is obtained by the above-described method. It is moved to the melt reservoir 23 by vapor transport. Alternatively, when the same crystal growth is performed next, the alkali metal melt 290 may be left as it is in the melt condensing unit 90A.

By preparing only the melt condensing part 90A with metal Na6 for generating the alkali metal melt 290, the mixed melt 270 is heated to 800 ° C., and the alkali metal melt 290 is raised to the evaporation suppression temperature Tevc. In the process in which the melt reservoir 23 is heated to the evaporation promotion temperature Tev, the amount of metal Na that evaporates from the mixed melt 270 and accumulates in the other portion as an alkali metal melt can be reduced. Variations in the mixing ratio of metal Na and metal Ga in the mixed melt 270 can be further suppressed.

In the second embodiment, the same change as the change from the crystal manufacturing apparatus 100 to the crystal manufacturing apparatus 100A may be added to the crystal manufacturing apparatus 100B. In this case, a GaN crystal is manufactured by the following two patterns. In the first pattern, metal Na6 is charged into the container 320, the container 320 is heated to the evaporation promotion temperature Tev by the heating / cooling device 70A, and the melt condensing unit 90A is heated to the evaporation suppression temperature Tev by the heating / cooling device 80A. The metal Na6 charged in the container 320 is vapor transported to the melt condensing unit 90A of the gas supply pipe 90 to produce a GaN crystal. After the GaN crystal is produced, the container 320 is brought to the condensation temperature Tcoh by the heating / cooling device 70A. In this pattern, the melt condensing unit 90A is heated to the evaporation promotion temperature Tev by the heating / cooling device 80A, and the alkali metal melt 290 is vapor-phase transported to the container 320 to prepare for the next GaN crystal production. . In the second pattern, metal Na6 is charged into the melt condensing unit 90A of the gas supply pipe 90, the container 320 is heated to the evaporation promotion temperature Tev by the heating / cooling device 70A, and the melt is condensed by the heating / cooling device 80A. 90A is heated to the evaporation suppression temperature Tevc to produce a GaN crystal. After the GaN crystal is produced, the container 320 is cooled to the condensation temperature Tcoh by the heating / cooling device 70A, and the melt condensing portion 90A is heated by the heating / cooling device 80A. Is heated to the evaporation promotion temperature Tev, and the alkali metal melt 290 is vapor-phase transported to the container 320 to prepare for the production of the next GaN crystal.

  The heating / cooling devices 70B and 80A and the temperature control device 260 constitute “control means”.

  The heating / cooling device 80A constitutes a “heating / cooling device”, and the heating / cooling device 70B constitutes “another heating / cooling device”, and controls the heating / cooling devices 70B and 80A. The control device 260 constitutes a “control device”.

Further, the melt condensing unit 90A constitutes a “melt reservoir”, and the melt reservoir 23 constitutes a “melt condensing unit”.

  Others are the same as in the first embodiment.

[Embodiment 3]
FIG. 22 is a schematic cross-sectional view of the crystal manufacturing apparatus according to the third embodiment. Referring to FIG. 22, the crystal manufacturing apparatus 100C according to the third embodiment includes a bellows 30, a support device 40, a pipe 180, a thermocouple 190, a gas supply pipe 200, a flow meter 210, a flow meter 210 of the crystal manufacturing apparatus 100 illustrated in FIG. The gas cylinder 220, the vibration application device 230, the vertical mechanism 240, and the vibration detection device 250 are deleted, and the temperature control device 260 is replaced with the temperature control device 260B. The rest is the same as the crystal manufacturing device 100.

  In the crystal manufacturing apparatus 100 </ b> C, one end of the gas supply pipe 90 is connected to the lid portion 22 of the reaction vessel 20.

  The temperature control device 260B is a function obtained by deleting the function of receiving the temperature T5 from the thermocouple 190 and generating the control signal CTL5 based on the received temperature T5 and outputting the control signal CTL5 to the flow meter 210 among the functions of the temperature control device 260. Have

  As described above, the crystal manufacturing apparatus 100C is a crystal manufacturing apparatus in which the function of cooling the seed crystal 5 and the function of moving the seed crystal 5 up and down so that the seed crystal 5 is brought into contact with the gas-liquid interface 2 are omitted from the crystal manufacturing apparatus 100. Equivalent to. That is, the crystal manufacturing apparatus 100 </ b> C is a crystal manufacturing apparatus that manufactures a GaN crystal without using the seed crystal 5. Therefore, in crystal manufacturing apparatus 100C, a GaN crystal is manufactured using the crystal growth temperature and nitrogen gas pressure included in region REG2 shown in FIG.

  When manufacturing a GaN crystal in the crystal manufacturing apparatus 100C, any of the charging method of metal Na6 shown in FIG. 6, the charging method of metal Na6 shown in FIG. 11, and the charging method of metal Na6 shown in FIG. 13 is used. It is done.

  FIG. 23 to FIG. 25 are first to third flowcharts in the third embodiment for explaining the method of manufacturing a GaN crystal, respectively.

When the preparation method of metal Na6 shown in FIG. 6 is used, a GaN crystal is manufactured according to the flowchart shown in FIG. The flowchart shown in FIG. 23 is the same as the flowchart shown in FIG. 10 except that steps S3, S8, S10, and S12 of the flowchart shown in FIG. 10 are deleted. In this case, in step S4, nitrogen gas is charged into the crucible 10 and the space 24 of the reaction vessel 20 so that the nitrogen gas pressure contained in the region REG2 shown in FIG. In addition, even when the GaN crystal is manufactured according to the flowchart shown in FIG. 23, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

When the preparation method of metal Na6 shown in FIG. 11 is used, a GaN crystal is manufactured according to the flowchart shown in FIG. The flowchart shown in FIG. 24 is the same as the flowchart shown in FIG. 12 except that steps S3, S8, S10, and S12 in the flowchart shown in FIG. 12 are deleted. In this case, in step S4, nitrogen gas is charged into the crucible 10 and the space 24 of the reaction vessel 20 so that the nitrogen gas pressure contained in the region REG2 shown in FIG. Also, when the GaN crystal is manufactured according to the flowchart shown in FIG. 24, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

When the preparation method of metal Na6 shown in FIG. 13 is used, a GaN crystal is manufactured according to the flowchart shown in FIG. The flowchart shown in FIG. 25 is the same as the flowchart shown in FIG. 14 except that steps S3, S8, S10, and S12 of the flowchart shown in FIG. 14 are deleted. In this case, in step S4, nitrogen gas is charged into the crucible 10 and the space 24 of the reaction vessel 20 so that the nitrogen gas pressure contained in the region REG2 shown in FIG. Also, when the GaN crystal is manufactured according to the flowchart shown in FIG. 25, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

  The crystal manufacturing apparatus according to Embodiment 3 may be a crystal manufacturing apparatus 100D shown in FIG. FIG. 26 is another schematic cross-sectional view of the crystal manufacturing apparatus according to the third embodiment. Referring to FIG. 26, crystal manufacturing apparatus 100D replaces reaction vessel 20 of crystal manufacturing apparatus 100C shown in FIG. 22 with reaction vessel 300, replaces heating / cooling device 70 with heating / cooling device 70A, and provides temperature sensor 71. Instead of the temperature sensor 71A, the temperature control device 260B is replaced with the temperature control device 260C, and a pipe 310, a container 320, a heating device 330, and a temperature sensor 331 are added, and the others are the same as the crystal manufacturing apparatus 100C.

  The reaction vessel 300, the heating / cooling device 70A, the temperature sensor 71A, the pipe 310, the vessel 320, the heating device 330, and the temperature sensor 331 are as described above.

  The temperature control device 260C receives the temperature T6 from the temperature sensor 331, generates a control signal CTL6 for setting the temperature of the pipe 310 to 800 ° C. (= crystal growth temperature) based on the received temperature T6, and heats it. Output to the device 330. In addition, the temperature control device 260C performs the same function as the temperature control device 260B.

When crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100D, 1) metal Na for generating the alkali metal melt 280, 290 is charged only in the container 320, and 2) the alkali metal melt 280, 290 is generated. One of the following is used: charging metal Na into the melt condensing unit 90A and the container 320; 3) charging metal Na to generate the alkali metal melts 280 and 290 only into the melt condensing unit 90A.

When the above 1) is used, crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100D according to the flowchart shown in FIG. When the above 2) is used, GaN crystals are grown in the crystal manufacturing apparatus 100D according to the flowchart shown in FIG. Furthermore, when the above 3) is used, crystal growth of a GaN crystal is performed in the crystal manufacturing apparatus 100D according to the flowchart shown in FIG. When the GaN crystal is grown according to any one of the flowchart shown in FIG. 23, the flowchart shown in FIG. 24, and the flowchart shown in FIG. 25, the metal Na evaporated from the alkali metal melt 280 held in the container 320 is obtained. so as to be substantially coincident to the vapor pressure _{P Na-Ga} of the metal Na vapor pressure _{P Na} evaporates from the melt mixture 270, the heating / cooling device 70A heats the container 320 to the evaporation inhibitor temperature TEVC.

Thus, in the third embodiment, the alkali metal melt 280 having the vapor pressure P _Na that substantially matches the vapor pressure P _Na—Ga of the metal Na evaporated from the mixed melt 270 is held in the reaction vessel 300. It is not necessary to be carried out and may be held outside the reaction vessel 300. In this case, the pipe 310 communicating the space 24 of the reaction vessel 300 and the space of the vessel 320 is heated by the heating device 330 to a crystal growth temperature, generally a temperature at which the metal Na vapor is not condensed . When the temperature of the pipe 310 is set to a temperature at which the metal Na vapor is condensed , the metal Na in the space 24 is condensed on the inner wall of the pipe 310, and the evaporation of the metal Na from the mixed melt 270 increases and mixing. Since the fluctuation of the mixing ratio of metal Na and metal Ga in the melt 270 becomes large, in order to prevent this, the temperature of the pipe 310 is set to a temperature at which the metal Na vapor is not condensed .

In addition, when a GaN crystal is manufactured using the crystal manufacturing apparatus 100D, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 held in the melt condensing unit 90A is stored in the container 320 by the above-described method. Vaporized to the gas phase.

  Others are the same as the crystal manufacturing apparatus 100C.

As described above, in the third embodiment, the vapor pressure P _Na-Ga of the metal Na evaporating from the mixed melt 270 is made substantially equal to the vapor pressure P _Na of the metal Na evaporating from the alkali metal melt 280. A GaN crystal is produced by nucleation.

  Therefore, according to the third embodiment, a GaN crystal can be produced by generating spontaneous nuclei while suppressing fluctuations in the mixing ratio of metal Na and metal Ga in the mixed melt 270.

  The heating / cooling devices 70 and 80 and the temperature control device 260B constitute “control means”.

  Further, the temperature control device 260B for controlling the heating / cooling devices 70 and 80 constitutes a “control device”.

  Furthermore, the heating / cooling devices 70A and 80 and the temperature control device 260C constitute “control means”.

  Furthermore, the temperature control device 260C that controls the heating / cooling devices 70A and 80 constitutes a “control device”.

  Others are the same as in the first embodiment.

[Embodiment 4]
FIG. 27 is a schematic cross-sectional view of the crystal manufacturing apparatus according to the fourth embodiment. Referring to FIG. 27, a crystal manufacturing apparatus 100E according to the fourth embodiment is obtained by replacing heating / cooling devices 70 and 80 of crystal manufacturing apparatus 100C shown in FIG. 22 with heating / cooling devices 70B and 80A, respectively. Others are the same as the crystal manufacturing apparatus 100C.

  The heating / cooling devices 70B and 80A are as described in the second embodiment.

  When a GaN crystal is manufactured using the crystal manufacturing apparatus 100E, any one of the charging method of metal Na6 shown in FIG. 18 and the charging method of metal Na6 shown in FIG. 20 is used.

  FIG. 28 and FIG. 29 are first and second flowcharts, respectively, in the fourth embodiment for explaining the method of manufacturing a GaN crystal.

When the preparation method of metal Na6 shown in FIG. 18 is used, a GaN crystal is manufactured according to the flowchart shown in FIG. The flowchart shown in FIG. 28 is the same as the flowchart shown in FIG. 19 except that steps S3, S8, S10, and S12 of the flowchart shown in FIG. 19 are deleted. In this case, in step S4, nitrogen gas is charged into the crucible 10 and the space 24 of the reaction vessel 20 so that the nitrogen gas pressure contained in the region REG2 shown in FIG. Also, when the GaN crystal is manufactured according to the flowchart shown in FIG. 28, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

When the preparation method of metal Na6 shown in FIG. 20 is used, a GaN crystal is manufactured according to the flowchart shown in FIG. The flowchart shown in FIG. 29 is the same as the flowchart shown in FIG. 21 except that steps S3, S8, S10, and S12 in the flowchart shown in FIG. 21 are deleted. In this case, in step S4, nitrogen gas is charged into the crucible 10 and the space 24 of the reaction vessel 20 so that the nitrogen gas pressure contained in the region REG2 shown in FIG. In addition, even when the GaN crystal is manufactured according to the flowchart shown in FIG. 29, when the crystal growth of the GaN crystal is completed, the alkali metal melt 290 accumulated in the melt condensing unit 90A is It is moved to the melt reservoir 23 by vapor transport.

By supplying the metal Na6 only to the melt condensing unit 90A, the mixed melt 270 is heated to 800 ° C., the alkali metal melt 290 is heated to the evaporation suppression temperature Tevc, and the melt reservoir 23 is evaporated. In the process of raising the temperature to the accelerating temperature Tev, the amount of metal Na that evaporates from the mixed melt 270 and accumulates in the other portion as an alkali metal melt can be reduced, and the metal Na and metal in the mixed melt 270 can be reduced. Variations in the mixing ratio with Ga can be further suppressed.

In the fourth embodiment, the same change as the change from the crystal manufacturing apparatus 100 to the crystal manufacturing apparatus 100A may be added to the crystal manufacturing apparatus 100E. In this case, a GaN crystal is manufactured by the following two patterns. In the first pattern, metal Na6 is charged into the container 320, the container 320 is heated to the evaporation promotion temperature Tev by the heating / cooling device 70A, and the melt condensing unit 90A is heated to the evaporation suppression temperature Tev by the heating / cooling device 80A. The metal Na6 charged in the container 320 is vapor transported to the melt condensing unit 90A of the gas supply pipe 90 to produce a GaN crystal. After the GaN crystal is produced, the container 320 is brought to the condensation temperature Tcoh by the heating / cooling device 70A. In this pattern, the melt condensing unit 90A is heated to the evaporation promotion temperature Tev by the heating / cooling device 80A, and the alkali metal melt 290 is vapor-phase transported to the container 320 to prepare for the next GaN crystal production. . In the second pattern, metal Na6 is charged into the melt condensing unit 90A of the gas supply pipe 90, the container 320 is heated to the evaporation promotion temperature Tev by the heating / cooling device 70A, and the melt is condensed by the heating / cooling device 80A. 90A is heated to the evaporation suppression temperature Tevc to produce a GaN crystal. After the GaN crystal is produced, the container 320 is cooled to the condensation temperature Tcoh by the heating / cooling device 70A, and the melt condensing portion 90A is heated by the heating / cooling device 80A. Is heated to the evaporation promotion temperature Tev, and the alkali metal melt 290 is vapor-phase transported to the container 320 to prepare for the production of the next GaN crystal.

  The rest is the same as in the first and third embodiments.

In the first to fourth embodiments described above, the temperature of the alkali metal melt 280 held in the melt reservoir 23 of the reaction vessel 20 and / or the melt condensing unit 90A of the gas supply pipe 90 are held. The vapor pressure P _{Na of} the metal Na evaporated from the alkali metal melt 280 and / or the alkali metal melt 290 by the heating / cooling devices 70, 70B and / or the heating / cooling devices 80, 80A. Suppresses the fluctuation of the mixing ratio of metal Na and metal Ga in the mixed melt 270 by controlling the evaporation suppression temperature Tevc to substantially coincide with the vapor pressure P _Na-Ga of the metal Na evaporating from the mixed melt 270 I explained that.

In the first to fourth embodiments described above, the temperature of the alkali metal melt 280 held in the vessel 320 outside the reaction vessel 300 and / or the melt condensing unit 90A of the gas supply pipe 90 are held. The temperature of the alkali metal melt 290 is mixed with the vapor pressure P _Na of the metal Na evaporating from the alkali metal melt 280 and / or the alkali metal melt 290 by the heating / cooling device 70A and / or the heating / cooling devices 80, 80A. By controlling the evaporation suppression temperature Tevc to substantially coincide with the vapor pressure P _Na-Ga of the metal Na evaporating from the melt 270, it is possible to suppress fluctuations in the mixing ratio of metal Na and metal Ga in the mixed melt 270. explained.

  In the crystal manufacturing apparatus according to the present invention, the temperature of the alkali metal melt of at least one of the two alkali metal melts 280 and 290 described above is the alkali metal vapor pressure that evaporates from the alkali metal. In general, it is not limited to the production of GaN crystals by controlling to an evaporation suppression temperature that substantially matches the vapor pressure, and in general, the evaporation of alkali metal from a mixed melt containing an alkali metal and a group III metal is suppressed. And a control means for controlling the temperature of the first alkali metal melt and / or the temperature of the second alkali metal melt to produce a group III nitride crystal.

  In the first to fourth embodiments described above, the crystal growth temperature is described as being 800 ° C. However, in the present invention, the crystal growth temperature is not limited to this, and the crystal growth temperature is not limited to that in the first embodiment. 2 may be the crystal growth temperature included in the region REG3 illustrated in FIG. 9, and may be any crystal growth temperature included in the region REG2 illustrated in FIG. 9 in the third and fourth embodiments. In the first and second embodiments, the nitrogen gas pressure may be any pressure included in the region REG3 shown in FIG. 9, and in the third and fourth embodiments, the pressure included in the region REG2 shown in FIG. If it is.

  Furthermore, the crystal manufacturing apparatus according to the first embodiment or the second embodiment may be one in which the vibration applying device 230, the vertical mechanism 240, and the vibration detecting device 250 are deleted from the crystal manufacturing apparatuses 100, 100A, 100B. In this case, the seed crystal 5 is not moved in the vertical direction, but is supported by the support device 40 so as to come into contact with the mixed melt 270 in a state where the metal Na and metal Ga put in the crucible 10 are melted. Therefore, the GaN crystal grows from the seed crystal 5 in a state in which the fluctuation of the mixing ratio between the metal Na and the metal Ga in the mixed melt 270 is suppressed. As a result, a large GaN crystal can be manufactured.

  Furthermore, the crystal manufacturing apparatus according to the first embodiment or the second embodiment is obtained by deleting the pipe 180, the thermocouple 190, the gas supply pipe 200, the flow meter 210, and the gas cylinder 220 from the crystal manufacturing apparatuses 100, 100A, and 100B. May be. In this case, the temperature T5 of the seed crystal 5 is not controlled to be lower than the temperature of the mixed melt 270 during crystal growth of the GaN crystal, but the seed crystal 5 is brought into contact with the mixed melt 270 by the support device 40. The GaN crystal grows from the seed crystal 5 in a state where the fluctuation of the mixing ratio of the metal Na and the metal Ga in the mixed melt 270 is suppressed. As a result, a large GaN crystal can be manufactured.

  Furthermore, the crystal manufacturing apparatus according to the first or second embodiment includes the pipe 180, the thermocouple 190, the gas supply pipe 200, the flow meter 210, the gas cylinder 220, the vibration applying apparatus 230, the crystal manufacturing apparatuses 100, 100A, and 100B. The vertical mechanism 240 and the vibration detection device 250 may be omitted. In this case, the seed crystal 5 is not moved in the vertical direction, and the temperature T5 of the seed crystal 5 is not controlled to a temperature lower than the temperature of the mixed melt 270, but the metal Na and the metal Ga contained in the crucible 10 Is supported by the support device 40 so as to contact the mixed melt 270 in a melted state. Therefore, the GaN crystal grows from the seed crystal 5 in a state in which the fluctuation of the mixing ratio between the metal Na and the metal Ga in the mixed melt 270 is suppressed. As a result, a large GaN crystal can be manufactured.

Further, in the above description, it has been described that metal Na and metal Ga are put in the crucible 10 in an Ar gas atmosphere, and metal Na is put in the melt reservoir 23 and / or the melt condensing unit 90A in the Ar gas atmosphere. In the present invention, not limited to this, metal Na and metal Ga are put in the crucible 10 in a gas atmosphere other than Ar gas such as He, Ne and Kr or in a nitrogen gas atmosphere, and the metal Na is stored in the melt reservoir 23 and / or. It may be put into the melt condensing part 90A, and generally, metal Na and metal Ga are put into the crucible 10 in an inert gas or nitrogen gas atmosphere, and the metal Na is put into the melt reservoir part 23 and / or melt condensed. What is necessary is just to put in the part 90A. In this case, the inert gas or nitrogen gas has a moisture content of 1 ppm or less and an oxygen content of 1 ppm or less.

  Furthermore, although it has been described that the metal mixed with the metal Ga is Na, in the present invention, the present invention is not limited to this, and alkali metals such as lithium (Li) and potassium (K), or magnesium (Mg), calcium ( Alkaline earth metals such as Ca) and strontium (Sr) may be mixed with metal Ga to form mixed melt 270. And those in which these alkali metals are dissolved constitute an alkali metal melt, and those in which these alkaline earth metals are dissolved constitute an alkaline earth metal melt.

  Furthermore, instead of nitrogen gas, a compound containing nitrogen as a constituent element such as sodium azide and ammonia may be used. These compounds constitute nitrogen source gas.

  Further, a group III metal such as boron (B), aluminum (Al), and indium (In) may be used instead of Ga.

  Therefore, the crystal manufacturing apparatus or manufacturing method according to the present invention generally manufactures a group III nitride crystal using a mixed melt of an alkali metal or alkaline earth metal and a group III metal (including boron). Anything is acceptable.

  The group III nitride crystal manufactured using the crystal manufacturing apparatus or method according to the present invention is used for manufacturing a group III nitride semiconductor device such as a light emitting diode, a semiconductor laser, a photodiode, and a transistor.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a crystal manufacturing apparatus that manufactures a group III nitride crystal while suppressing a variation in the mixing ratio between an alkali metal and a group III metal. In addition, the present invention is applied to a manufacturing method for manufacturing a group III nitride crystal while suppressing a variation in the mixing ratio between an alkali metal and a group III metal.

It is a schematic sectional drawing of the crystal manufacturing apparatus by Embodiment 1 of this invention. It is an enlarged view of the support apparatus, piping, and thermocouple shown in FIG. It is the schematic which shows the structure of the up-and-down mechanism shown in FIG. It is a timing chart of a vibration detection signal. It is a timing chart of the temperature of a crucible, a reaction container, a melt reservoir part, and a melt condensation part shown in FIG. It is a schematic diagram which shows the state change in a crucible, a reaction container, a melt reservoir part, and a melt condensation part between the timings t1 and t3 shown in FIG. It is a schematic diagram which shows the state in the crucible and reaction container in the timing t3 shown in FIG. It is a figure which shows the relationship between the temperature of a seed crystal, and the flow volume of nitrogen gas. It is a figure which shows the relationship between the nitrogen gas pressure in the case of growing a GaN crystal, and crystal growth temperature. 4 is a flowchart in the first embodiment for explaining a method of manufacturing a GaN crystal. FIG. 6 is another schematic diagram showing state changes in the crucible, the reaction vessel, the melt reservoir, and the melt condensing unit between the timings t1 and t3 shown in FIG. 6 is another flowchart in the first embodiment for explaining a method of producing a GaN crystal. FIG. 6 is still another schematic diagram illustrating a state change in the crucible, the reaction vessel, the melt reservoir, and the melt condensing unit between the timings t1 and t3 illustrated in FIG. 5. 12 is still another flowchart in the first embodiment for explaining a method for producing a GaN crystal. 4 is another schematic cross-sectional view of the crystal manufacturing apparatus according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a crystal manufacturing apparatus according to Embodiment 2. FIG. It is a timing chart of the temperature of a crucible, a reaction container, a melt reservoir part, and a melt condensing part shown in FIG. It is a schematic diagram which shows the state change in a crucible, a reaction container, a melt reservoir part, and a melt condensation part between the timings t1 and t3 shown in FIG. It is a flowchart in Embodiment 2 for demonstrating the manufacturing method of a GaN crystal. FIG. 18 is another schematic diagram showing state changes in the crucible, the reaction vessel, the melt reservoir, and the melt condensing unit between the timings t1 and t3 shown in FIG. It is another flowchart in Embodiment 2 for demonstrating the manufacturing method of a GaN crystal. 6 is a schematic cross-sectional view of a crystal manufacturing apparatus according to Embodiment 3. FIG. It is a 1st flowchart in Embodiment 3 for demonstrating the manufacturing method of a GaN crystal. It is a 2nd flowchart in Embodiment 3 for demonstrating the manufacturing method of a GaN crystal. It is a 3rd flowchart in Embodiment 3 for demonstrating the manufacturing method of a GaN crystal. 6 is another schematic cross-sectional view of a crystal manufacturing apparatus according to Embodiment 3. FIG. 6 is a schematic cross-sectional view of a crystal manufacturing apparatus according to Embodiment 4. FIG. It is a 1st flowchart in Embodiment 4 for demonstrating the manufacturing method of a GaN crystal. It is a 2nd flowchart in Embodiment 4 for demonstrating the manufacturing method of a GaN crystal.

1, 2, gas-liquid interface, 4 nitrogen gas, 5 seed crystal, 10 crucible, 20,300 reaction vessel, 20A, 41A outer peripheral surface, 20B, 41B, 180A bottom surface, 21,301 body portion, 22 lid portion, 23 melt Reservoir, 24 spaces, 30 bellows, 40 support device, 41 cylindrical member, 42, 43 fixing member, 44 space portion, 50, 60, 330 heating device, 51, 61, 71, 71A, 81, 331 temperature sensor, 70, 70A, 70B, 80, 80A Heating / cooling device, 90, 91, 92, 200 Gas supply pipe, 90A Melt condensing section, 100, 100A, 100B, 100C, 100D, 100E Crystal manufacturing apparatus, 110, 150 Valve 120 pressure regulator, 130, 220 gas cylinder, 140 exhaust pipe, 160 vacuum pump, 170 pressure sensor, 180 piping, 181 air hole, 90 thermocouple, 190A, 411 one end, 210 flow meter, 230 vibration application device, 240 vertical mechanism, 241 uneven member, 242 gear, 243 shaft member, 244 motor, 245 control unit, 246, 247 arrow, 250 vibration detection device 260, 260A, 260B, 260C Temperature control device, 270 Mixed melt, 280, 290 Alkali metal melt.

Claims (5)

A production method for producing a Group III nitride crystal using a mixed melt containing an alkali metal and a Group III metal and held in a crucible in a container, and a nitrogen source gas,
A first step in which the alkali metal and the group III metal are set in the crucible in an inert gas or nitrogen gas atmosphere;
A first region existing on a path through which the nitrogen source gas is supplied to the container space in the inert gas or the nitrogen gas atmosphere, and communicates with the container space and is different from the first region. A second step of setting the alkali metal in at least one of the second regions;
A third step of supplying a nitrogen source gas to the container space;
A fourth step of heating the crucible to a crystal growth temperature;
A fifth step of controlling the temperature of the alkali metal melt present in the first region to a condensation temperature and controlling the temperature of the alkali metal present in the second region to an evaporation suppression temperature ,
The evaporation suppression temperature is an alkali in which the vapor pressure of alkali metal evaporating from at least one of the alkali metal melt existing in the first region and the alkali metal melt existing in the second region evaporates from the mixed melt. The manufacturing method , wherein the temperature is substantially equal to a vapor pressure of the metal, and the condensation temperature is a temperature at which alkali metal vapor is accumulated in the first region as a metal melt . The temperature of the crucible is heated to the crystal growth temperature for a predetermined period, the temperature of the alkali metal melt present in the first region is controlled to the condensation temperature, and the alkali present in the second region The manufacturing method according to claim 1 , further comprising a sixth step of controlling the temperature of the metal melt to the evaporation suppression temperature. When the predetermined period has elapsed, the temperature of the alkali metal melt existing in the first region is controlled to the evaporation promoting temperature, and the alkali metal melt existing in the second region is controlled to the condensation temperature. 7 steps are further provided,
The said evaporation promotion temperature is a manufacturing method of Claim 2 which is the temperature at which the said alkali metal melt moves to another part by vapor-phase transport. A sixth step in which a seed crystal is held so as to be in contact with an interface between the mixed melt and the container space or soaked in the mixed melt;
In the third step, the nitrogen source gas is supplied to the container space so that the pressure in the container space is set to a seed crystal growth pressure at which a group III nitride crystal grows from the seed crystal,
The manufacturing method according to claim 1 , wherein in the fourth step, the crucible is heated so that the temperature of the crucible is set to a seed crystal growth temperature at which a group III nitride crystal grows from the seed crystal. In the third step, the nitrogen source gas is supplied to the container space so that the pressure in the container space is set to a nucleation pressure at which multinucleation occurs from the interface between the mixed melt and the crucible,
In the fourth step, the crucible is heated so as to set the temperature of the crucible to nucleation temperature polynuclear generated from the interface occurs between the crucible and the molten mixture, either of claims 1 to 3 The production method according to claim 1.

Images