JP2020001950A - Vapor phase growth apparatus - Google Patents

Abstract

To remove easily a seed substrate from a tray.SOLUTION: A vapor phase growth apparatus includes a tray loading a seed substrate, and arranging the seed substrate on a position opposite to an inflow direction of raw material gas, and a susceptor loading the tray. The tray has a substrate loading part where the seed substrate is loaded, and a holding part for holding the substrate loading part at a prescribed distance from the susceptor, and the holding part has a taper part whose outer periphery is reduced gradually from the substrate loading part toward the susceptor side.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a vapor phase growth apparatus.

  A GaN substrate, which is an example of a group III nitride semiconductor substrate, is manufactured by processing a GaN bulk single crystal mainly manufactured using a hydride vapor phase epitaxy (HVPE) method. The HVPE method has an advantage that the growth rate is higher than that of the metal organic chemical vapor deposition method (MOCVD method), and a thick GaN bulk crystal can be obtained in a relatively short time. In the HVPE method, a thick substrate GaN bulk crystal is formed on a seed substrate by heating a seed substrate positioned on a substrate mounting portion of a tray with a heater and blowing a source gas onto the heated seed substrate. (Patent Document 1).

JP 2007-320849 A

  However, in the HVPE method, a large amount of polycrystals may be continuously generated from near the tray to the susceptor simultaneously with the formation of crystals. In some cases, the generated polycrystalline body connects the seed substrate, the tray, and the susceptor, making it difficult to remove the seed substrate.

  The present disclosure is a means for solving the above problems, and has as its object to provide a vapor phase growth apparatus that can easily remove a seed substrate from a tray.

  In order to solve the above problems, the vapor phase growth apparatus of the present invention is mounted with a seed substrate, a tray for arranging the seed substrate at a position facing the inflow direction of the source gas, and a susceptor for mounting the tray, Is provided. The tray has a substrate mounting portion on which the seed substrate is mounted, and a holding portion for holding the substrate mounting portion at a predetermined distance from the susceptor, wherein the holding portion is configured to move the susceptor from the substrate mounting portion. It has a tapered portion whose outer circumference decreases toward the side.

  According to the present invention, there is provided a vapor phase growth apparatus capable of easily removing a seed substrate from a tray.

FIG. 1 is a schematic diagram showing a schematic configuration of a vapor phase growth apparatus according to an embodiment of the present invention. FIG. 2A is a schematic cross-sectional view showing a configuration example of a conventional tray and susceptor provided in the vapor phase growth apparatus, and FIG. 2B is a diagram illustrating a crystal growth using the vapor phase growth apparatus including the tray and susceptor shown in FIG. 2A. It is a schematic cross section which shows a state of a tray and a susceptor after. FIG. 3 is a schematic cross-sectional view showing a configuration example of a tray and a susceptor provided in the vapor phase growth apparatus according to one embodiment of the present invention. FIG. 4A shows a crystal growth using a vapor phase growth apparatus including a tray in which the distance between the surface of the susceptor on the substrate mounting portion side and the surface of the tapered portion on the substrate mounting portion side is less than the thickness of the crystal to be grown. FIG. 4B is a schematic cross-sectional view showing the state of the tray after the growth, and FIG. 4B is a crystal film in which the distance between the surface of the substrate mounting portion of the susceptor and the surface of the taper portion on the substrate mounting portion side is grown. FIG. 4 is a schematic cross-sectional view showing a state of a tray after crystal growth using a vapor phase growth apparatus including a tray having a thickness of not less than thickness.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of a vapor phase growth apparatus 100 which is a vertical HVPE apparatus in the present embodiment.

  The vapor phase growth apparatus 100 includes a reactor 110, a heater 120 provided around the reactor 110, a tray 130 provided in the reactor 110, a susceptor 140 on which the tray 130 is mounted, and a tray of the susceptor 140. A heater 151 disposed on the side opposite to 130, a support shaft 152 having a rotation function, and a pipe 161, a pipe 162, a pipe 163, a pipe 164, and a pipe 165 are provided.

  The reactor 110 is a container for performing a vapor phase growth method such as an HVPE method. The reaction furnace 110 is formed of a material such as quartz, which has high heat resistance and hardly causes an unnecessary reaction with an introduced gas.

  The heater 120 heats the inside of the reaction furnace 110 to a temperature suitable for crystal growth by a vapor phase growth method, and maintains the heated temperature. The temperature for heating and maintaining may be set according to the type of crystal to be grown.

  The tray 130 is a pedestal for mounting a seed substrate and growing a crystal from the seed substrate. In the present embodiment, the seed substrate is disposed on the tray 130 at a position facing the inflow direction of the source gas from the pipes 161 and 162 described later. The tray 130 is formed of a material such as quartz, carbon, silicon carbide, and boron nitride that has high heat resistance and hardly causes an unnecessary reaction with an introduced gas.

  The susceptor 140 is a pedestal on which the tray 130 is mounted.

  The heater 151 heats the tray 130 via the susceptor 140, heats the seed substrate mounted on the tray 130 to a temperature suitable for crystal growth by vapor phase epitaxy, and maintains the heated temperature. The temperature for heating and maintaining may be set according to the type of crystal to be grown.

  The support shaft 152 rotates the susceptor 140 and the tray 130 mounted on the susceptor 140. The support shaft 152 rotates the tray 130 to suppress the bias of crystal growth on the tray 130.

The piping 161 and the piping 162 allow the source gas containing the source material of the crystal to be grown to flow into the reactor 110. In this embodiment, the pipe 161 contains a group III element chloride (such as gallium chloride (GaCl _x )), and the pipe 162 contains a group V element hydride (such as AsH ₃ , NH ₃ (ammonia) and PH ₃ ). It flows into the reactor 110.

  In the present embodiment, the pipe 161 communicates the raw material box 166 with the inside of the reaction furnace 110. A group III element (Ga or the like) is charged inside the raw material box 166, and gallium chloride generated by the reaction of Ga and hydrogen chloride gas introduced from the outside through the pipe 167 into the raw material box 166 is produced. Flows into the reaction furnace 110 from the pipe 161.

  The piping 163 and the piping 164 allow the carrier gas to flow into the reaction furnace 110. In the present embodiment, the pipe 163 allows hydrogen gas to flow, and the pipe 164 allows nitrogen gas to flow into the reactor 110.

  The pipe 165 discharges a carrier gas or the like that has flowed into the reaction furnace 110 to the outside of the reaction furnace 110.

  When crystal growth is performed using the vapor phase growth apparatus 100, after the seed substrate is mounted on the tray 130, the inside of the reaction furnace 110 is sufficiently purged with nitrogen gas introduced from the pipe 163, and Remove any remaining oxygen. Thereafter, the inside of the reaction furnace 110 and the seed substrate are heated to the crystal growth temperature by the heater 120 and the heater 151, and the temperature is maintained. After that, a source gas containing a source material of a crystal to be grown flows into the reaction furnace 110 from the pipe 161 and the pipe 162. At this time, the carrier gas flows into the reaction furnace 110 from the pipe 164 and the pipe 164 as necessary. The raw material contained in the raw material gas reacts on the seed substrate, and a crystal (for example, a GaN bulk single crystal) grows.

The seed substrate can be a metal oxide crystal or a group III nitride semiconductor crystal. Examples of the metal oxide crystals, sapphire, silicon carbide, silicon include gallium arsenide, and ScMgAlO _4. Examples of the group III nitride crystal include GaN.

  According to the HVPE method, the growth time can be reduced to about 1/50 to 1/400 as compared with the MOCVD method. Generally, a GaN bulk single crystal for the purpose of manufacturing a GaN substrate requires a film thickness of 1 mm or more. Therefore, the HVPE method, which has a high crystal growth rate and can form a thick film in a short time, is a method suitable for growing a GaN bulk single crystal.

  By the way, in the above-mentioned HVPE method, after the crystal growth is completed and the temperature of the reactor 110 is cooled to room temperature, the tray 130 is removed from the reactor 110, and the crystal formed on the tray 130 is removed from the tray 130. Obtain a crystalline film. At this time, it is known that a polycrystal is parasitically attached to the tray 130 in connection with a target crystal. Therefore, the target polycrystal is obtained by removing the connected polycrystal by polishing and processing.

  FIG. 2A is a schematic cross-sectional view showing a configuration example of a conventional tray 230 and a susceptor 240 provided in the above-described vapor phase growth apparatus, and FIG. 2B is a vapor phase growth including the tray 230 and the susceptor 240 shown in FIG. 2A. FIG. 4 is a schematic cross-sectional view showing a state of a tray 230 and a susceptor 240 after crystal growth using the apparatus. When the vapor phase growth is performed using the tray 230 as shown in FIG. 2A, as shown in FIG. 2B, the polycrystal 280 is continuously generated from the tray 230 onto the susceptor 240, and the seed substrate 270 and the tray Since seed 230 and susceptor 240 are connected, seed substrate 270 is firmly fixed to tray 230 and susceptor 240, and it is difficult to remove seed substrate 270 from tray 230.

  FIG. 3 is a schematic cross-sectional view illustrating a configuration example of the tray 130 and the susceptor 140 included in the vapor phase growth apparatus 100 according to the present embodiment. The tray 130 has a substrate mounting part 132 on which the seed substrate is mounted, and a holding part 134 for holding the substrate mounting part 132.

  The substrate mounting section 132 is a stage on which a seed substrate is mounted.

  The holding section 134 is a pedestal that holds the board mounting section 132 at a predetermined distance from the susceptor 140. In the present embodiment, the holding portion 134 is a cylindrical pedestal having a hollow interior to enhance thermal conductivity, and has a tapered portion 134a formed to extend to the outside at an end on the substrate mounting portion 132 side.

  The upper surface of the tapered portion 134a is a surface that continuously extends to the outside from the surface of the substrate mounting portion 132 on which the seed substrate is mounted, and the outer periphery of the side surface is reduced along the flow direction of the source gas. Having a tapered shape. On the upper surface of the tapered portion 134a, the polycrystal grown around the seed substrate can grow along the substrate mounting portion 132 to the end of the tapered portion 134a. However, on the side surface of the tapered portion 134a, the source gas flowing from the pipe 161 and the pipe 162 is unlikely to reach the side surface, so that the growth of polycrystal is suppressed. That is, the polycrystal grown on the tray 130 is prevented from growing in the direction of the susceptor 140 by the tapered portion 134a. Therefore, the tapered portion 134a makes it difficult for the holding portion 134 of the tray 130 and the susceptor 140 to be continuously covered with the grown polycrystal, and the tray 130 and the susceptor 140 can be easily removed.

  Further, in the present embodiment, the holding portion 134 is disposed closer to the susceptor 140 than the tapered portion 134a, and is formed continuously with the end of the tapered portion 134a on the susceptor 140 side, which is parallel to the flow direction of the source gas. And a facing portion 134b having

  As will be described later, the taper portion 134a preferably has a more acute taper angle θ between the plane on which the seed substrate of the substrate mounting portion 132 is mounted and the tapered side surface. On the other hand, the holding unit 134 is required to hold the seed substrate at a predetermined distance from the susceptor 140. The facing portion 134b moves the seed substrate from the susceptor 140 even when the taper angle θ of the tapered portion 134a is made more acute by making the end of the tapered portion 134a on the susceptor 140 side farther away from the susceptor 140. By separating, the distance between the seed substrate and the susceptor 140 can be secured.

  At this time, it is preferable that the facing portion 134b has an outer periphery that extends outside the outer periphery of the substrate mounting portion 132. Thereby, the cross-sectional area of the hollow space formed inside the facing portion 134b can be increased, and the heat transfer efficiency can be further increased. Also, at this time, the side surface of the facing portion 134b formed in the holding portion 134 on the outer side in parallel with the flow direction of the raw material gas is likely to come into contact with the heated raw material gas flowing from the pipes 161 and 162. Therefore, a decrease in heat transfer efficiency due to the cooling of the facing portion 134b can be suppressed.

  In this embodiment, the distance between the surface of the substrate mounting portion 132 of the susceptor 140 and the surface of the tapered portion 134a on the substrate mounting portion is equal to or more than the thickness of the crystal to be grown (for example, 1 mm or more). Preferably, there is.

  FIG. 4A shows a vapor phase growth including a tray 130 in which the distance between the surface of the susceptor 140 on the substrate mounting portion 132 side and the surface of the tapered portion 134a on the substrate mounting portion 132 side is less than the thickness of the crystal to be grown. FIG. 4 is a schematic cross-sectional view showing a state of a tray 130 after crystal growth from a seed substrate 170 using the apparatus. At this time, the polycrystal 180a that is parasitically attached to the tray 130 and grows to the end of the upper surface of the tapered portion 134a (in this embodiment, the same plane as the surface of the tapered portion 134a on the substrate mounting portion 132 side). And the polycrystal 180b grown on the surface of the susceptor 140 on the substrate mounting portion 132 side may be connected, and it may be difficult to remove the tray 130 and the susceptor 140.

  FIG. 4B shows a vapor phase growth apparatus including a tray 130 in which the distance between the surface of the substrate mounting portion 132 of the susceptor 140 and the surface of the tapered portion 134a on the substrate mounting portion 132 is equal to or larger than the thickness of the crystal to be grown. FIG. 4 is a schematic cross-sectional view showing a state of a tray 130 after crystal growth from a seed substrate 170 using the method shown in FIG. At this time, the polycrystal 180a that is parasitically attached to the tray 130 and grows to the end of the upper surface of the tapered portion 134a (in this embodiment, the same plane as the surface of the tapered portion 134a on the substrate mounting portion 132 side). And the polycrystal 180b grown on the surface of the susceptor 140 on the substrate mounting portion 132 side is difficult to connect, so that the tray 130 and the susceptor 140 can be easily removed.

(Verification on taper angle θ)
The film is formed by HVPE using the vapor phase growth apparatus according to the present embodiment, which includes a tray having a distance of 5 mm between the surface of the substrate mounting portion of the susceptor and the surface of the substrate mounting portion of the taper portion. A GaN bulk single crystal was formed on a seed substrate with a thickness of 5 mm. The taper angle θ formed between the plane on which the seed substrate of the substrate mounting portion 132 is mounted and the tapered side surface is changed in three stages of 45 °, 60 °, and 90 °, and the flow rate of the source gas is The seed substrate is changed in three stages: a reference flow rate at which a GaN crystal can be easily formed, a reference flow rate × 0.5 times the flow rate, and a reference flow rate × 0.1 times the flow rate. We verified whether it could be easily removed from the tray.

  Table 1 shows the results.

  According to the results shown in Table 1, when the taper angle θ was 45 ° to 60 ° when the flow rate was × 0.5 times the reference flow rate, the seed substrate could be easily removed from the tray. However, when the taper angle θ is 45 °, the seed substrate can be easily removed from the tray at the reference flow rate × 0.1, but when the taper angle θ is 60 °, the seed substrate can be easily removed from the tray. I couldn't do that.

  From this result, it is understood that the taper angle is preferably an acute angle. The taper angle is preferably an acute angle from the viewpoint of making it difficult for the raw material gas to enter the side surface of the tray and forming a polycrystal on the side surface of the tapered portion. For example, the taper angle can be 60 ° or less, and preferably 45 ° or less. The minimum value of the taper angle is not particularly limited, but may be 10 ° or more.

  Further, the cover having the tapered portion or the straight wall portion described above may be covered with a conventional tray to form a tray having the shape of the present embodiment.

  It can be used for manufacturing a group III nitride semiconductor base substrate or a group III nitride semiconductor free-standing substrate used as a substrate for epitaxial growth in an optical device such as a light emitting diode for lighting and a vehicle, and a high frequency electronic device. .

Reference Signs List 100 vapor growth apparatus 110 reaction furnace 120 heater 130 tray 132 substrate mounting part 134 holding part 134a taper part 134b face part 140 susceptor 151 heater 152 support shaft 161 pipe 162 pipe 163 pipe 164 pipe 165 pipe 166 source box 167 pipe 170 types 180a, 180b Polycrystalline 230 Tray 240 Susceptor 270 Seed substrate 280 Polycrystalline

Claims (7)

A tray on which a seed substrate is mounted and the seed substrate is arranged at a position facing the inflow direction of the source gas,
A susceptor for mounting the tray,
The tray is
A substrate mounting unit on which the seed substrate is mounted,
A holding unit for holding the substrate mounting unit at a predetermined distance from the susceptor,
The holding portion has a tapered portion whose outer circumference decreases from the substrate mounting portion toward the susceptor.
Vapor growth equipment.   2. The vapor phase growth apparatus according to claim 1, wherein the holding unit has a facing portion that is disposed closer to the susceptor than the tapered portion and has a side surface that is parallel to an inflow direction of the source gas.   The vapor phase growth apparatus according to claim 2, wherein the facing portion has an outer periphery that extends outside an outer periphery of the substrate mounting portion.   The vapor phase growth apparatus according to claim 1, wherein a taper angle of the tapered portion is equal to or less than 60 °.   The distance between the surface of the susceptor on the substrate mounting portion side and the surface of the tapered portion on the substrate mounting portion side is equal to or greater than the thickness of the crystal to be grown. Item 10. The vapor phase growth apparatus according to Item 1.   The air gap according to any one of claims 1 to 5, wherein a distance between a surface of the susceptor on the substrate mounting portion side and a surface of the tapered portion on the substrate mounting portion side is 1 mm or more. Phase growth equipment.   The vapor phase growth apparatus according to any one of claims 1 to 6, capable of growing GaN.

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