JP5205631B2 - Crystal manufacturing method and crystal manufacturing apparatus - Google Patents

Description

  The present invention relates to a crystal manufacturing method and a crystal manufacturing apparatus.

  Compound semiconductors, among them Group III element nitrides such as gallium nitride (GaN) (hereinafter sometimes referred to as Group III nitrides, Group III nitride semiconductors, or GaN-based semiconductors) emit blue or ultraviolet light. It is attracting attention as a material for semiconductor elements. Blue laser diodes (LDs) are applied to high-density optical discs and displays, and blue light-emitting diodes (LEDs) are applied to displays and lighting. Further, ultraviolet LD is expected to be applied to biotechnology and the like, and ultraviolet LED is expected to be an ultraviolet source of fluorescent lamps.

  A group III nitride semiconductor (for example, GaN) substrate for an LD or LED is usually formed by heteroepitaxially growing a group III nitride single crystal on a sapphire substrate using a vapor phase epitaxial growth method. . Examples of the vapor deposition method include a metal organic chemical vapor deposition method (MOCVD method), a hydride vapor deposition method (HVPE method), a molecular beam epitaxy method (MBE method), and the like.

On the other hand, a method of performing crystal growth in a liquid phase instead of vapor phase epitaxial growth has been studied. Since the equilibrium vapor pressure of nitrogen at the melting point of a group III nitride single crystal such as GaN or AlN is 10,000 atmospheres or more, conventionally, gallium nitride is grown at 1200 ° C. at 8000 atmospheres (8000 × 1) in the liquid phase. .01325 × 10 ⁵ Pa) has been required. On the other hand, in recent years, it has been clarified that GaN can be synthesized at a relatively low temperature and low pressure of 750 ° C. and 50 atm (50 × 1.01325 × 10 ⁵ Pa) by using an alkali metal such as Na.

Recently, a mixture of Ga and Na was melted at 800 ° C. and 50 atm (50 × 1.01325 × 10 ⁵ Pa) in a nitrogen gas atmosphere containing ammonia, and this melt was used for a growth time of 96 hours. A single crystal having a maximum crystal size of about 1.2 mm is obtained (for example, see Patent Document 1).

  FIG. 6 shows a conventional group III element nitride crystal manufacturing apparatus by liquid phase growth. For the sake of explanation, the case of producing a GaN crystal is taken as an example. 13 is a raw material gas supply device for supplying nitrogen gas, which is a raw material gas, 14 is a hermetic crystal growth vessel for crystal growth, 15 is a connecting pipe for connecting the raw material gas supply device 13 and the crystal growth vessel 14, 23 is a growth furnace equipped with a heating means. The connection pipe 15 includes a pressure regulator 16, a stop valve 17, a leak valve 18, and a disconnecting portion 19. The growth furnace 23 is configured as an electric furnace including a heat insulating material 20 and a heater 21. The temperature of the growth furnace 23 is controlled by a thermocouple 22 and the whole can be swung.

  In the manufacturing apparatus having such a configuration, the seed substrate 2 is set in the crucible 1. This seed substrate 2 is arranged in a direction parallel to the bottom surface of the crucible 1. Further, a predetermined amount of metal gallium and Na as raw materials are weighed and set in the crucible 1.

Then, the crucible 1 is inserted into the crystal growth vessel 15, and this crystal growth vessel 14 is set in the growth furnace 23 and connected to the source gas supply device via the connection pipe 15, and the growth temperature is 850 ° C. and the nitrogen atmosphere. A pressure of 50 atm (50 × 1.01325 × 10 ⁵ Pa) is applied, nitrogen gas is dissolved in a Ga / Na melt (hereinafter referred to as a raw material solution), and a GaN single crystal is grown on the seed substrate 2.

  Since the produced GaN single crystal is in the crucible together with the solidified raw material solution, the GaN single crystal must be taken out from this state.

  7 to 8 show a method for taking out a GaN single crystal manufactured by the manufacturing apparatus of FIG. In a state where the crucible 1 is taken out from the crystal growth vessel 14 at room temperature, the raw material liquid is a solid raw material 4, and the GaN single crystal grown on the seed substrate 2 cannot be taken out as it is. Therefore, as shown in FIG. 7, the crucible 1 is placed in a processing vessel 8 filled with the solid raw material treatment liquid 9, and the solid raw material treatment liquid 9 and the solid raw material 4 are chemically reacted to dissolve the solid raw material 4 from the upper surface. Go. Here, when a Ga / Na treatment liquid is used as a raw material, it is possible to dissolve the solid raw material 4 while generating hydrogen as the reaction gas 10 by using ethanol as the solid raw material treatment liquid 9.

  Further, the raw material liquid enters between the bottom surface of the crucible 1 and the seed substrate 2, and the solid raw material 4 exists in a thin layer shape. As shown in FIG. 8, after the solid raw material 4 above the GaN single crystal is processed, the solid raw material treatment liquid 9 circulates from the outer peripheral side of the seed substrate 2, and between the bottom surface of the crucible 1 and the GaN single crystal 2. The existing solid raw material 4 is melted. When all the solid raw materials 4 are processed, the GaN single crystal 2 and the crucible 1 are separated, and the GaN single crystal 2 can be taken out from the crucible 1.

JP 2002-293696 A

  However, in the conventional configuration, when the GaN single crystal is removed from the crucible, the solidified solid material is removed by treatment with a solid raw material treatment liquid such as ethanol. Needed. In particular, since the solid raw material formed in the gap between the seed substrate formed on the bottom surface of the seed substrate and the bottom surface of the crucible is in a state where the entire bottom surface of the seed substrate is in contact with the inner bottom surface of the crucible, Since the surface range of the solid raw material in contact with the solid raw material treatment liquid is limited to a narrow range in the vertical direction of this gap, the processing takes time. Furthermore, since the area of the solid raw material in contact with the inner bottom surface of the crucible is large, it took several days to dissolve the solid raw material in this range, and there was a problem that productivity was poor.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a crystal production method and an apparatus thereof with high productivity capable of taking out crystals from a solid raw material in a short time.

  And in order to achieve this object, the present invention, before putting the crucible into the processing vessel, or after putting the crucible into the processing vessel, let the solid raw material processing liquid flow, into the crucible, The crystal substrate generated on this seed substrate and the seed substrate and the solid raw material covering the crystal substrate are stored, and at least one or more holes are provided on the bottom surface or side surface of the crucible. did.

  This achieves the intended purpose.

  As described above, the present invention allows the solid raw material treatment liquid to flow into the processing container before or after the crucible is placed in the processing container, and the seed crucible and the seed substrate are placed in the crucible. And the seed substrate and the solid material covering the crystal substrate are accommodated, and at least one or more holes are provided in the bottom or side surface of the crucible. Therefore, productivity can be increased.

  That is, since at least one or more holes are provided in the bottom surface or bottom surface of the crucible, the solid raw material treatment liquid can flow in from the holes, so that the range in which the solid raw material treatment liquid is in contact with the solid raw material is widened. It can be dissolved quickly.

  In addition, when a hole is made in the bottom surface, the solid material existing between the seed substrate and the bottom surface in the crucible that can take the longest can be dissolved from the beginning, so that the seed substrate can be taken out in a few hours. Thus, productivity can be increased.

Sectional drawing of a part of the crystal manufacturing apparatus of Embodiment 1 Initial solid raw material treatment process using the crystal production apparatus of the first embodiment Slope / cross-sectional view of crucible fixing base of Embodiment 1 Late solid raw material treatment process using the crystal production apparatus of the first embodiment Partial sectional view of the crystal manufacturing apparatus of the second embodiment Schematic configuration cross-sectional view of an apparatus for performing a general group III nitride single crystal manufacturing method Conventional initial solid raw material treatment process diagram Conventional late-stage solid material treatment process diagram

  Embodiments of the method and apparatus for producing a product crystal of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a part of a crystal manufacturing apparatus according to an embodiment of the present invention. As shown in FIG. 1, a cup-shaped crucible 1 made of a heat-resistant material such as alumina, a seed substrate positioning jig 5 similarly made of a heat-resistant material, and a seed substrate 2 for growing a nitride crystal on the surface It is configured. A seed substrate positioning jig 5 is installed on the crucible inner bottom surface 7 of the crucible 1, and the seed substrate positioning jig 5 holds the seed substrate 2 at a predetermined position on the crucible inner bottom surface 7.

  Next, a method for producing a crystal will be described. First, a crystal element material (for example, gallium, aluminum, indium) and an alkali metal (for example, lithium, sodium, potassium) or an alkaline earth metal (for example, calcium, strontium, barium, Supply radium, beryllium, magnesium). These alkali metals and alkaline earth metals may be used alone or in combination of two or more. The weighing and handling of the crystal element material and the alkali metal are preferably performed in a glove box substituted with nitrogen gas, argon gas, neon gas or the like in order to avoid oxidation of the alkali metal and moisture adsorption.

  Next, the crucible 1 is inserted into the crystal growth vessel 14 shown in FIG. 8, taken out from the glove box in a sealed state, and the crystal growth vessel 14 is fixed in the growth furnace 23. Thereafter, the crystal growth vessel 14 and the connecting pipe 15 are connected, the stop valve 17 is opened, and the source gas is injected from the source gas supply device 13 into the crystal growth vessel 14.

  Then, pressurization and heating are performed by controlling the temperature of the growth furnace 23 and the pressure of the growth atmosphere by the thermocouple 22 and the pressure regulator 16. The conditions for melting and growing the raw material for generating crystals depend on the raw crystal material and the alkali metal component, the raw material gas component and the pressure thereof. For example, the temperature is 700 ° C. to 1100 ° C. Preferably, a low temperature of 700 ° C. to 900 ° C. is used. The pressure is 20 atmospheres (20 × 1.01325 × 105 Pa) or more, preferably 30 atmospheres (5 × 1.01325 × 105 Pa) to 100 atmospheres (100 × 1.01325 × 105 Pa).

  In this way, by raising the temperature to the growth temperature, a crystal element material / alkali metal melt, that is, a raw material liquid is formed in the crucible 1, and the raw material gas is dissolved in the raw material liquid. A crystal substrate is grown on the seed substrate 2 by reacting with the gas.

  After a predetermined time has elapsed and the growth of the group III element nitride single crystal is completed, the growth furnace 23 is returned to normal pressure and room temperature, the crystal growth vessel 14 and the connecting pipe 15 are removed, and the crystal growth vessel 23 is removed from the growth furnace 23. 14 is taken out. Further, the crucible 1 is taken out from the crystal growth vessel 23.

  Here, only about 5 to 30% of the crystal element material remains in the raw material liquid in the crucible 1 after crystal growth shown in FIG. 2, and most of them are alkali metals. Further, the raw material liquid exists as a solid raw material 4 at room temperature, and covers the seed substrate 2 and the seed substrate positioning jig 5 on which the crystal substrate 3 is integrally formed. The crucible hole 6 is opened on the side and bottom of the crucible 1 using a drill or the like. At this time, since the seed substrate 2 is positioned by the seed substrate positioning jig 5, the positions of the seed substrate 2 and the crystal substrate 3 in the crucible can be grasped, and when the crucible hole 6 is opened, the seed substrate 2 and the crystal are mistakenly formed. There is no fear of damaging the substrate 3. In particular, when the seed substrate 2 is positioned at the center of the crucible inner bottom surface 7 by the seed substrate positioning jig 5, the size of the gap between the crucible inner peripheral surface and the seed substrate outer periphery no matter what position on the side of the crucible is drilled. Therefore, it is only necessary to control the amount of movement of the drill. Moreover, what is necessary is just to open a hole in the position of the seed substrate positioning jig 5 when opening a hole in a crucible inner bottom face with a drill.

  Next, in order to take out the seed substrate 2 on which the crystal substrate 3 is integrally formed, the solid raw material 4 is processed. The cut crucible 1 is fixed to a crucible fixing base 11 installed in a processing vessel 8, and an arbitrary solid raw material treatment liquid 9 containing a hydroxyl group (-OH), for example, alcohols such as ethanol, methanol, isopropyl alcohol, or water is injected. To do. By immersing the solid raw material 4 in the solid raw material treatment liquid 9, a metal alkoxide (a metal hydroxide in the case of using water) and hydrogen as the reaction gas 10 are generated in the treatment liquid, and the solid raw material 4 is obtained. To process. Since the crucible hole 6 is formed in the crucible 1, not only the upper surface of the solid raw material 4 but also the portion of the crucible hole 6 is in contact with the solid raw material processing liquid 8, so that the processing time can be shortened.

  As shown in FIG. 2, a crucible fixing base 11 that supports the crucible with respect to the inner bottom surface of the processing vessel 8 is provided, and the crucible fixing base 11 has a plurality of support portions arranged at predetermined intervals. ing.

  The support portions of these crucible fixing bases 11 can be formed by partially cutting the crucible fixing base 11 or can be formed by dividing the crucible fixing base 11 into a plurality of parts.

  More specifically, FIG. 3 shows the crucible fixing base 11 partially cut. From this cutting part, it is possible to supply the solid raw material processing liquid 9 to the crucible hole 6 formed in the crucible inner bottom surface 7. In FIG. 3, the crucible fixing base 11 is formed by one component. However, even when a plurality of crucible fixing bases 11 are used, the crucible fixing base 11 is formed on the bottom surface 7 in the crucible from between the support portions of the respective crucible fixing bases 11. It is possible to supply the solid raw material treatment liquid 9 to the crucible hole 6.

  As the processing of the solid material 4 proceeds, the solid material 4 remains in the gap between the seed substrate 2 and the seed substrate support 3 as shown in FIG. 4, but when the crucible hole 6 is formed in the bottom surface 7 of the crucible, Since the solid raw material treatment liquid 9 is immersed in the solid raw material 4 in the gap immediately after the start, the processing time can be further shortened.

  When the processing of the solid raw material 4 is completed, the seed substrate 2 on which the crystal substrate 3 is integrally formed, the crucible 1 and the seed substrate support 4 are separated, so that the crystal substrate 10 and the seed substrate 2 are removed from the crucible 1. It can be taken out.

  A seed substrate 2 having a diameter of 50 mm is placed in a crucible 1 having an inner diameter of 90 mm, a GaN single crystal is grown using gallium and sodium as raw materials, and a solid raw material in which the distance between the upper surface of the solid raw material 4 and the upper surface of the crystal substrate 10 is 10 mm An experiment was conducted in which 4 was treated with ethanol. In the conventional example, the time for processing the solid material 4 around the seed substrate 2 and the crystal substrate 10 (the time from FIG. 7 to FIG. 8) is 4 hours, and the solid material existing in the gap between the crucible inner bottom surface 7 and the seed substrate 2. It takes about 50 hours to process 4. On the other hand, in this embodiment, when four crucible holes 6 each having a diameter of 10 mm are formed on the side surface of the crucible and the bottom surface in the crucible, the time for processing the solid raw material 4 around the seed substrate 2 (time from FIG. 2 to FIG. 4) However, it took about 30 hours to process the solid raw material 4 existing in the gap between the bottom surface 15 of the crucible 1 and the seed substrate support 3 for 3 hours, and the time was significantly reduced.

(Embodiment 2)
A crystal manufacturing apparatus according to Embodiment 2 of the present invention is shown in FIG. In FIG. 5, the difference from the configuration of the first embodiment is that the bottom surface 7 in the crucible 1 of the crucible 1 is processed and the seed substrate positioning portion 12 is formed integrally with the crucible 1. Thus, even if the seed substrate positioning part 12 is integrally formed with the crucible 1 and the seed substrate positioning jig is eliminated, the same effect as in the first embodiment can be obtained, and the crystal substrate 3 and the seed substrate 2 can be quickly mounted. You can take it out. Furthermore, since it is integrally formed with the crucible, the number of parts can be reduced and the productivity can be increased.

  The crystal manufacturing method and apparatus according to the present invention have an effect of taking out a group III element nitride crystal such as a GaN single crystal formed by liquid phase growth from a raw material solution in a short time, It is useful for manufacturing a substrate of a semiconductor element used for a blue light emitting diode or the like.

1 crucible 2 seed substrate 3 crystal substrate 4 solid raw material 5 seed substrate positioning jig 6 crucible hole 7 bottom surface of crucible 8 processing vessel 9 solid raw material processing liquid 10 reaction gas 11 crucible fixing base 12 seed substrate positioning unit 13 source gas supply device 14 crystal Growth vessel 15 Connection pipe 16 Pressure regulator 17 Stop valve 18 Leak valve 19 Separation part 20 Heat insulating material 21 Heater 22 Thermocouple 23 Growth furnace

Claims (8)

A method for producing a crystal in which a crystal substrate grown in a crucible is taken out of a solid material,
Before or after putting the crucible into the processing container, the solid raw material processing liquid is allowed to flow into the processing container, and in the crucible, a seed substrate, a crystal substrate generated on the seed substrate, and A crystal manufacturing method in which these seed substrate and solid raw material covering the crystal substrate are stored, and at least one or more holes are provided on the bottom surface or side surface of the crucible. A crucible fixing base that supports the crucible with respect to the inner bottom surface of the processing container,
The crystal manufacturing method according to claim 1, further comprising a plurality of support portions arranged at predetermined intervals. The crystal manufacturing method according to claim 2, wherein the support portion of the crucible fixing base is formed by partially cutting the crucible fixing base. The crystal manufacturing method according to claim 2, wherein the support portion of the crucible fixing base is formed by dividing the crucible fixing base into a plurality of parts. The crystal manufacturing method according to claim 1, wherein the seed substrate is positioned by a seed substrate positioning jig. The crystal manufacturing method according to claim 1, wherein the seed substrate is positioned by a seed substrate positioning portion formed in the bottom surface of the crucible. The crystal manufacturing method according to claim 1, wherein the seed substrate is a gallium nitride substrate. A crystal substrate manufacturing apparatus used in the method for manufacturing a crystal substrate according to claim 1, wherein the processing vessel table, an inflow means for allowing the solid raw material processing liquid to flow into the processing vessel, and the crucible And a take-out means for taking out the crystal substrate and the seed substrate from the processing container after the solid raw material is dissolved in the solid raw material treatment liquid.

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