JP4560310B2 - Method for manufacturing substrate of group III nitride crystal - Google Patents

Description

The present invention relates to the production how the substrate of the Group III nitride.

Conventionally, as shown in, for example, Patent Document 1, a group III nitride crystal growth method for growing a group III nitride crystal by reacting a group III metal and nitrogen in a melt containing an alkali metal (that is, Flux method) is known.
JP-A-2003-292400

However, in the conventional flux method, there is a problem that the low III-nitride crystal dislocation density have difficulty be grown.

  Specifically, for example, when a group III nitride crystal is grown using a seed crystal, the group III nitride crystal that can be used for the seed crystal is not always low in dislocation density.

Further, even when using a seed crystal dislocation density is not lower, it was not difficult to crystal growth with low III-nitride crystal dislocation density.

The present invention aims at providing a method for manufacturing a substrate for crystals of possible III-nitride of making a low quality Group III nitride crystal substrate dislocation density.

In order to achieve the above object, the invention according to claim 1 is a method for producing a group III nitride crystal substrate, wherein at least an alkali metal, a group III metal and nitrogen are dissolved in a group III nitride crystal. Growing a group III nitride crystal while forming a {10-11} plane that is not the main surface of the substrate as a growth surface with respect to the seed crystal, and among the group III nitride crystals, it is characterized by a step of preparing a substrate to the main surface of the specified crystal plane be processed portions that are low dislocation density than the seed crystal.

According to a second aspect of the present invention, in the method for manufacturing a group III nitride crystal substrate according to the first aspect , the seed crystal is a hexagonal crystal .

According to a third aspect of the present invention, in the method for producing a group III nitride crystal substrate according to the first aspect , the seed crystal is a plate crystal .

According to the first aspect of the present invention, there is provided a method for producing a group III nitride crystal substrate, wherein seeds are grown when a group III nitride crystal is grown from a melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved. A step of growing a group III nitride crystal while forming a {10-11} plane which is not the main surface of the substrate as a growth surface with respect to the crystal, and the group III nitride crystal is lower than the seed crystal. since a specific crystal plane by processing the portion which is dislocation density and a step of preparing a substrate for said main surface, a group III nitride while forming a {10-11} plane in the seed crystal as the growth surface By growing the crystal, even when the dislocation density of the seed crystal is large, the crystal can be grown while suppressing the propagation of the dislocation to the crystal plane other than the {10-11} plane. Therefore, even if a seed crystal having a high dislocation density is used, for example, a crystal having a (0001) plane with a low dislocation density can be easily produced. And since it is a board | substrate which makes the principal surface the specific crystal plane (for example, (0001) plane) produced by processing a group III nitride crystal, penetration of the desired specific crystal plane (for example, (0001) plane) It is possible to provide a high-quality group III nitride crystal substrate having a low dislocation density.

  Hereinafter, the best mode for carrying out the present invention will be described.

This onset Ming, grown in at least an alkali metal and the group III metal and the crystal growth method of the nitrogen from the dissolved melt for growing the Group III nitride crystal, the crystal plane other than the specific crystal plane (e.g., (0001)) It is characterized by crystal growth while forming as a plane.

According to the above configuration, in a crystal growth method for growing a group III nitride crystal from a melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved, a crystal plane other than a specific crystal plane (for example, (0001) plane) Since the crystal is grown while forming as a growth surface, a high-quality group III nitride crystal having a low dislocation density can be produced.

  In other words, since dislocations tend to propagate toward the growth plane, when growing while forming a crystal plane other than the desired specific crystal plane (for example, (0001) plane) as the growth plane, a specific crystal plane (for example, Dislocations hardly propagate to (0001) plane. Therefore, in the first embodiment, it is possible to produce a crystal whose desired specific crystal plane (for example, (0001) plane) has a low dislocation density.

Further, the present invention is characterized in that, in the above configuration, the group III nitride is crystal-grown while forming a {10-11} plane as a growth plane as a crystal plane other than the specific crystal plane.

According to the above, since the group III nitride crystal is grown while forming the {10-11} plane as a growth plane as a crystal plane other than the specific crystal plane, the crystal plane other than the {10-11} plane is grown. Crystal growth can be easily performed while suppressing the propagation of dislocations. Therefore, for example, a crystal having a (0001) plane with a low dislocation density can be easily produced.

  Here, the {10-11} plane can be easily formed by appropriately selecting the conditions of the flux method.

  When crystal growth is performed while forming this {10-11} plane as a growth plane, crystal growth can be easily performed while suppressing the propagation of dislocations to crystal planes other than the {10-11} plane. Therefore, for example, a crystal having a (0001) plane with a low dislocation density can be easily produced.

Further, the present invention is characterized in that, in the above-described configuration , the group III nitride is crystal-grown while forming a {10-11} plane as a growth surface in the seed crystal.

According to this configuration, since the group III nitride crystal is grown while forming the {10-11} plane as a growth surface in the seed crystal, even if the dislocation density of the seed crystal is high, other than the {10-11} plane Crystal growth can be achieved while suppressing the propagation of dislocations to the crystal plane. Therefore, even if a seed crystal having a high dislocation density is used, for example, a crystal having a (0001) plane with a low dislocation density can be easily produced.

  1 and 2 show a case where a group III nitride crystal is grown using a hexagonal pyramid crystal 1 having a {10-11} plane as a seed crystal. 2 is a cross-sectional view of FIG.

  FIG. 3 shows a case where a group III nitride crystal is grown using a plate crystal 2 having a (0001) plane as a main surface as a seed crystal.

  In both cases of FIGS. 2 and 3, the crystal tops A and B of the grown group III nitride crystal are less likely to propagate dislocations and have a low dislocation density (low dislocation density).

A group III nitride crystal produced by any of the above-described crystal production methods is obtained.

Further, if the above Symbol of crystal manufacturing method III nitride made with crystals, a specific crystal plane (e.g. (0001) plane) of the threading dislocation density is less high-quality group III-nitride crystal to a desired Can be provided.

  Specifically, a group III nitride crystal grown using a hexagonal pyramid crystal 1 having a {10-11} plane as a seed crystal has a low dislocation density in the upper portion A of the crystal as shown in FIG. Yes. In addition, as shown in FIG. 3, a group III nitride crystal grown using a plate-like crystal 2 having a (0001) plane as a main surface as a seed crystal has a low dislocation density in the upper part B of the crystal. .

The present invention is characterized in that it is a substrate whose principal surface is a specific crystal plane (for example, (0001) plane) produced by processing a group III nitride crystal obtained as described above .

Further, according to the present invention, since the substrate has a specific crystal plane (for example, (0001) plane) produced by processing the group II / II nitride crystal as described above, the specific crystal plane desired A high-quality group III nitride crystal substrate having a low threading dislocation density (for example, (0001) plane) can be provided.

  Specifically, for example, a group III nitride crystal grown as shown in FIG. 2 is shown in a portion indicated by a broken line C as shown in FIG. 4 (in the example of FIG. 4, it passes through the vicinity of the upper part A of the crystal (0001) plane). This can be cut into a substrate (low dislocation density substrate) having a specific crystal plane ((0001) plane) as a main surface as shown in FIG.

A semiconductor device can be manufactured on a specific crystal plane (for example, (0001) plane) of the group III nitride crystal obtained by the present invention or on a substrate .

According to the above configuration, since the semiconductor device is manufactured on a specific crystal plane (for example, (0001) plane) of a group III nitride crystal or on a substrate, a high-performance and high-reliability semiconductor device can be obtained. Can be provided.

  FIG. 6 shows an example of a device fabricated on a low dislocation density (0001) plane substrate (substrate of FIG. 5) formed by cutting and polishing the group III nitride crystal of FIG. Has been. Since this device is fabricated on a (0001) plane substrate (substrate in FIG. 5) having a low dislocation density, it has high performance and high reliability.

  In Example 1, Na (sodium) is used as an alkali metal, Ga (gallium) is used as a Group III metal raw material, nitrogen gas is used as a nitrogen raw material, and a GaN seed crystal having a (0001) plane as a main surface, GaN was grown as a group III nitride. Here, Na and Ga were previously held in a melt holding container as a mixed melt, and nitrogen was dissolved from the gas phase into the melt to grow GaN crystals.

FIG. 7 is a diagram illustrating a configuration example of the crystal manufacturing apparatus used in the first embodiment.

The crystal manufacturing apparatus of FIG. 7 is provided with a melt holding vessel 12 for holding a melt 22 containing an alkali metal and a group III metal in a closed reaction vessel 11 made of stainless steel and performing crystal growth. ing.

  The melt holding container 12 can be removed from the reaction container 11. The material of the melt holding container 12 is BN.

Also, nitrogen (N ₂₎ as a nitrogen source in the interior space 19 of the reaction vessel 11 is filled with gas, and nitrogen in the reaction vessel 11 (N ₂₎ gas supply pipe 14 which allows to adjust the pressure reaction The container 11 is mounted through.

  The pressure of the nitrogen gas can be adjusted by the pressure control device 16.

  The total pressure in the reaction vessel 11 is monitored with a pressure gauge 18.

  A heater 13 is installed outside the reaction vessel 11.

  The reaction vessel 11 can be removed from the crystal growth apparatus at the valve 21 portion, and only the reaction vessel 11 portion can be put into the glove box for operation.

Below, the crystal growth method of GaN in Example 1 using the crystal manufacturing apparatus of FIG. 7 is demonstrated.

  First, the reaction vessel 11 is separated from the crystal growth apparatus at the valve 21 and placed in a glove box in an Ar atmosphere.

  Next, a GaN seed crystal 24 having a (0001) plane as a main surface, gallium (Ga), and sodium (Na) are placed in the melt holding container 12 made of BN.

  Next, the melt holding container 12 is placed on the melt holding container holding stand 20 and installed in the reaction container 11.

  Next, the reaction vessel 11 is sealed, the valve 21 is closed, and the inside of the reaction vessel 11 is shut off from the external atmosphere.

  Next, the reaction vessel 11 is taken out of the glove box and incorporated in the crystal growth apparatus.

  That is, the reaction vessel 11 is installed at a predetermined position with the heater 13 and connected to the nitrogen gas supply line 14 at the valve 21 portion.

  Next, the valves 15 and 21 are opened, and nitrogen gas is introduced into the reaction vessel 11. At this time, the nitrogen pressure was set to 1 MPa by the pressure control device 16. This pressure is a pressure at which the total pressure in the reaction vessel 11 becomes 1.5 MPa when the temperature is raised to the crystal growth temperature (775 ° C.) in the apparatus used in Example 1.

  Next, the valve 15 and the valve 21 are closed. Thereby, the reaction container 11 is sealed.

  Next, the heater 13 is energized to raise the temperature of the melt 22 from room temperature (27 ° C.) to the crystal growth temperature in one hour. The crystal growth temperature was 775 ° C.

  The pressure in the sealed reaction vessel 11 increased following the temperature increase, and the total pressure in the reaction vessel 11 when the crystal growth temperature reached 775 ° C. became 1.5 MPa.

  After holding in this state for 500 hours, the temperature is lowered to room temperature.

When the reaction vessel 11 was opened after the completion of crystal growth, hexagonal pyramid-shaped GaN 23 formed on the {10-11} plane was growing on the seed crystal 24.

GaN crystal 23 was grown, the defect density of the crystal top was ¹⁰ 6 ^{cm -2} or less in the etch pit density evaluation.

  The present invention can be used for a blue-violet light source for optical disks, an ultraviolet light source (entire surface), a blue-violet light source for electrophotography, a group III nitride electronic device, and the like.

It is a figure which shows the case where a group III nitride crystal is crystal-grown using the hexagonal pyramid crystal which has a {10-11} plane as a seed crystal. It is a figure which shows the case where a group III nitride crystal is crystal-grown using the hexagonal pyramid crystal which has a {10-11} plane as a seed crystal. It is a figure which shows the case where a group III nitride crystal is crystal-grown using the plate-like crystal which makes (0001) plane the main surface as a seed crystal. It is a figure which shows the position C which cut | disconnects the crystal | crystallization of FIG. FIG. 5 is a diagram showing a substrate manufactured by cutting the crystal of FIG. 2 at a position C in FIG. 4. It is a figure which shows the semiconductor device produced on the board | substrate of FIG. 1 is a diagram illustrating a configuration example of a crystal manufacturing apparatus used in Example 1. FIG.

1, 2 Seed crystal 11 Reaction vessel 12 Melt holding vessel 13 Heater 14 Gas supply pipe 15, 21 Valve 16 Pressure control device 18 Pressure gauge 23 GaN
24 seed crystals

Claims (3)

A method for producing a group III nitride crystal substrate, comprising:
When a group III nitride crystal is grown from a melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved, a {10-11} plane that is not the main surface of the substrate is formed as a growth surface with respect to the seed crystal. While growing a group III nitride crystal,
III-nitride, which comprises a step of preparing a substrate for said group III said major surface a specific crystal plane be processed portions that are low dislocation density than the seed crystal of the nitride crystal Method for manufacturing a crystal substrate.   2. The method for manufacturing a group III nitride crystal substrate according to claim 1, wherein the seed crystal is a hexagonal crystal.   2. The method for producing a group III nitride crystal substrate according to claim 1, wherein the seed crystal is a plate crystal.

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