JP4335717B2 - Group III nitride crystal manufacturing method - Google Patents

Description

The present invention relates to crystal manufacturing how the III-nitride.

Conventionally, as shown, for example, in Patent Document 1, a Group III nitride crystal manufacturing method in which a Group III metal and nitrogen are reacted in a melt containing an alkali metal to grow a Group III nitride crystal (that is, Flux method) is known.

FIG. 7 is a diagram illustrating a configuration example of the crystal manufacturing apparatus disclosed in Patent Document 1. In FIG. Referring to FIG. 7, a mixed melt 102 of a group III metal (for example, Ga (gallium)) and a flux (for example, metal Na or a compound containing Na (such as sodium azide)) is contained in the reaction vessel 101. Contained. The reaction vessel 101 is provided with a heating device 105 that can be controlled to a temperature at which crystals can be grown.

  Further, a seed crystal (for example, GaN crystal) 103 is provided so as to be in contact with a gas-liquid interface 113 which is a boundary region between the gas in the reaction vessel 101 and the melt 102.

  Further, nitrogen gas is used as the nitrogen raw material, and a first gas supply device 120 is provided outside the reaction vessel 101 in order to supply the nitrogen gas into the reaction vessel 101. Here, the first gas supply device 120 includes a first cylinder 110 for storing a gaseous nitrogen raw material, and a first valve 111. Thereby, nitrogen gas can be supplied from outside the reaction vessel 101 into the reaction vessel 101 through the nitrogen supply pipe 106 from the first cylinder 110 of the first gas supply device 120 filled with nitrogen gas. Yes.

  In order to adjust the nitrogen pressure, a pressure adjusting mechanism is provided in the middle of the nitrogen supply pipe 106. This pressure adjustment mechanism for nitrogen gas includes a pressure sensor 107 and a pressure adjustment valve 108, and pressure information measured by the pressure sensor 107 is transmitted to the pressure adjustment valve 108 via the cable 109, and the pressure adjustment valve 108 The pressure is adjusted, and the nitrogen pressure in the reaction vessel 101 is set to a desired value.

  The nitrogen gas pressure in the first cylinder 110 filled with nitrogen gas is equal to or higher than the pressure in the reaction vessel 101 generated when a group III nitride (eg, GaN) crystal grows. Filled.

  Therefore, the nitrogen gas as the nitrogen source is supplied from the first cylinder 110, the gas pressure of the nitrogen source is adjusted by the pressure adjustment mechanism, and is supplied into the reaction vessel 101.

Using the crystal manufacturing apparatus having such a configuration, a group III nitride crystal (for example, a GaN crystal) grows using the seed crystal 103 as a nucleus under conditions of a growth temperature at which crystal growth is possible, a nitrogen pressure, and an amount of Na. Using a melt 102 containing an alkali metal (for example, Na) and a group III metal (for example, Ga (gallium)) and a nitrogen gas supplied from outside, the size of the group III nitride crystal increases with time. To go.

As described above, in the invention of Patent Document 1, in a state where there is sufficient Group III metal and alkali metal (for example, Na), nitrogen gas as a nitrogen source is supplied from the outside, so that a Group III nitride crystal ( GaN crystal) can be grown, and a group III nitride crystal (GaN crystal) can be grown to a desired size.
JP 2001-64097 A

In the conventional crystal manufacturing method, a mixed melt containing an alkali metal and a group III metal is held in a melt holding container, and nitrogen is dissolved from the gas phase to perform crystal growth.

  Therefore, when the distance from the gas-liquid interface of the melt to the crystal surface is long, the time required for nitrogen to diffuse from the gas-liquid interface to the crystal becomes long, and the growth rate is not necessarily high because the growth rate is limited. It was.

  For this reason, in Patent Document 1, the seed crystal is held near the gas-liquid interface, the nitrogen diffusion distance is shortened, and crystal growth is performed in a region where the growth rate is high. However, in order to increase the size of the crystal, a means for moving the crystal up or down in accordance with the growth of the seed crystal is required, which causes a problem that the apparatus configuration is complicated.

  In addition, the growth of minute scrap crystals on the inner wall of the melt holding container often occurs at the same time, and the raw material is consumed by these scrap crystals, and the supply of raw materials to seed crystals or specific crystals is insufficient. Is one of the reasons for slowing down. Insufficient supply of these raw materials is a factor for lowering crystal quality such as generation of nitrogen defects.

  In the conventional method, since crystal growth is performed in the mixed melt held in the melt holding container, it is difficult to grow the crystal only in a specific region on the substrate. In this case, a complicated process such as forming a mask pattern on the substrate and growing the crystal is required.

According to the present invention, when a group III nitride crystal is grown, the growth rate can be increased without complicating the apparatus configuration, and a high-quality group III nitride crystal can be produced. and its object is to provide a crystalline Manufacturing method nitride.

Furthermore, an object of the present invention is to provide a group III nitride crystal manufacturing method capable of growing a group III nitride crystal in an arbitrary pattern shape and crystal size at a specific position.

To achieve the above object, a first aspect of the present invention, the crystal surface of the substrate or the group III nitride crystal was dropped or placed droplets of melt containing a group III metal, care melting liquid A mixed melt is formed by supplying an alkali metal and nitrogen from the phase and dissolving, and a group III nitride composed of nitrogen and a group III metal is crystal-grown.

The invention according to claim 2 is the method for producing a group III nitride crystal according to claim 1 , wherein a predetermined pattern is formed with a melt on the substrate or the crystal surface of the group III nitride crystal, It is characterized in that a group III nitride crystal is grown thereon.

According to the first aspect of the present invention, a droplet of a melt containing a group III metal is dropped or placed on the crystal surface of a substrate or a group III nitride crystal, and alkali metal and nitrogen are introduced into the melt from the gas phase. To form a mixed melt by growing and crystal growth of group III nitride composed of nitrogen and group III metal, so that when the alkali metal melts from the melt surface, nitrogen penetration occurs, Nitrogen supply from the gas-liquid interface increases. As a result, the growth rate is increased, nitrogen deficiency is reduced, and a high-quality crystal can be grown.

Further, according to the second aspect of the present invention, in the crystal production method according to claim 1 III nitride described, on the crystal surface of the substrate or the group III-nitride crystal to form a predetermined pattern in the melt By growing a group III nitride crystal on the pattern, a group III nitride crystal can be grown at a specific position. Specifically, for example, a group III nitride crystal can be arranged in an arbitrary shape, or an arbitrary pattern shape can be produced with a group III nitride crystal.

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

( First reference example )
In a first reference example of the present invention, a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed on a substrate, and the group III is removed from the droplet of the mixed melt. It is characterized by growing a nitride crystal.

FIG. 1 is a diagram for explaining a first reference example . In the example of FIG. 1, Na (sodium) is used as the alkali metal and Ga is used as the group III metal. That is, in the example of FIG. 1, a Ga—Na—N mixed melt is formed to grow GaN crystals.

According to the first reference example , a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed on a substrate, and a group III nitridation is performed from the droplet of the mixed melt. Since the crystal is grown, the distance between the gas-liquid interface and the growth region can be shortened, thereby increasing the supply of nitrogen (N2) from the gas-liquid interface and increasing the growth rate of the group III nitride crystal. Can be increased. Further, nitrogen deficiency is reduced, and a high-quality group III nitride crystal can be grown.

( Second reference example )
In a second reference example of the present invention, a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed on a substrate, and the group III is removed from the droplet of the mixed melt. After growing the nitride crystal, the mixed melt is removed, and a droplet of the mixed melt is dropped or placed again on the crystal surface of the grown group III nitride crystal to grow the group III nitride. Is repeated a plurality of times to grow a group III nitride crystal.

FIG. 2 is a diagram for explaining a second reference example . In the example of FIG. 2, Na (sodium) is used as the alkali metal and Ga is used as the group III metal. That is, in the example of FIG. 2, first, GaN crystal grows in a mixed melt of Ga, Na, and N (step S1). When GaN crystal grows, Ga disappears, the growth ends, and only Na is in the melt (step S2). Then, Na of the melt is evaporated (step S3), and only the GaN crystal remains (step S4). Then, the process returns to step S1 again, and the GaN growth step (S1 to S4) is repeated.

According to the second reference example , a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed on a substrate, and a group III nitride crystal is formed from the mixed melt. After the growth, the mixed melt is removed, and the droplet of the mixed melt is dropped or placed again on the surface of the grown group III nitride crystal, and the group III nitride is repeatedly grown several times. Thus, the group III nitride crystal is grown, and the melt is removed after the crystal growth. Therefore, the crystal composition can always be controlled by controlling the melt composition.

( First form )
According to a first aspect of the present invention, a droplet of a melt containing a group III metal is dropped or placed on a crystal surface of a substrate or a group III nitride crystal, and alkali metal and nitrogen are added to the melt from a gas phase. A mixed melt is formed by supplying and dissolving, and a group III nitride composed of nitrogen and a group III metal is crystal-grown.

FIG. 3 is a diagram for explaining the first embodiment . In the example of FIG. 3, Na (sodium) is used as the alkali metal and Ga is used as the group III metal. That is, in the example of FIG. 3, Na and N are supplied from the gas phase, and Na and N are dissolved in the Ga melt to grow GaN crystals.

Thus, according to the first embodiment , a droplet of a melt containing a group III metal is dropped or placed on the crystal surface of a substrate or a group III nitride crystal, and an alkali metal from the gas phase is placed on the melt. And nitrogen is supplied and dissolved to form a mixed melt, and a group III nitride composed of nitrogen and a group III metal is crystal-grown. An alkali metal and nitrogen are added to the group III metal melt. Since it melt | dissolves, when an alkali metal melt | dissolves from a melt surface, nitrogen melt | dissolution occurs and the supply of nitrogen from a gas-liquid interface increases. As a result, the growth rate is increased, nitrogen deficiency is reduced, and a high-quality crystal can be grown.

( Third reference example )
In the third reference example of the present invention, a droplet of a melt containing a group III metal and an alkali metal is dropped or placed on a substrate or a crystal surface of a group III nitride crystal, and nitrogen is dissolved in the melt. Thus, a mixed melt is formed, and a group III nitride composed of nitrogen and a group III metal is crystal-grown.

FIG. 4 is a diagram for explaining a third reference example . In the example of FIG. 4, Na (sodium) is used as the alkali metal and Ga is used as the group III metal. That is, in the example of FIG. 4, N is supplied from the gas phase, N is dissolved in the Ga—Na melt, and GaN is crystal-grown.

Thus, according to the third reference example , a droplet of a melt containing a group III metal and an alkali metal is dropped or placed on the crystal surface of a substrate or a group III nitride crystal, and nitrogen is added to the melt. In order to grow a group III nitride composed of nitrogen and a group III metal, the nitrogen is dissolved in the group III metal and alkali metal mixed melt. The amount ratio of the group III metal to the alkali metal in the melt can be controlled, and the crystal growth can be performed by always controlling the growth conditions.

( Second form )
Second embodiment of the present invention, in the crystal production method of a group III nitride of the first form state is characterized by specifying the position to form a melt.

In the second embodiment , a group III nitride crystal can be grown at a specific position by forming the melt at a specific position. Specifically, for example, a group III nitride crystal can be arranged in an arbitrary shape, or an arbitrary pattern shape can be produced with a group III nitride crystal. FIG. 5 shows an example in which group III nitride crystals are arranged in a predetermined shape.

The group III nitride crystal growth method according to the second aspect is characterized in that a predetermined pattern is formed with a melt, and a group III nitride crystal is grown on the pattern.

  FIG. 6 shows, as an example, an example in which a predetermined pattern P is formed with a Ga melt. Na and N are dissolved in a Ga melt having the shape of this pattern P, and GaN having a pattern P's shape. Can be grown (produced).

Thus, in this embodiment, an arbitrary pattern shape can be produced with a group III nitride crystal.

( Fourth reference example )
In a fourth reference example of the present invention, a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed on a seed crystal placed on a substrate, and the mixture is mixed. It is characterized by growing group III nitride crystals from melt droplets.

According to the fourth reference example , on the seed crystal placed on the substrate, a droplet of a mixed melt in which at least an alkali metal, a group III metal, and nitrogen are dissolved is dropped or placed, and the mixed melt is added. A group III nitride crystal is grown from the liquid droplets, and a group III nitride crystal having a desired plane orientation can be grown by using a seed crystal.

In the group III nitride crystal manufactured by the crystal production method of the present invention, it is possible to provide a nitrogen deficiency is less high-quality group III-nitride crystal.

In a semiconductor device manufactured using a group II nitride crystal manufactured according to the embodiment of the present invention, a high-quality group III nitride crystal is used. Can be provided.

  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 for demonstrating the 1st reference example . It is a figure for demonstrating the 2nd reference example . It is a figure for demonstrating a 1st form . It is a figure for demonstrating the 3rd reference example . It is a figure which shows the example which arranged the group III nitride crystal in the predetermined shape. It is a figure which shows the example which formed the predetermined pattern P with Ga melt. It is a figure which shows the structural example of the crystal growth apparatus of patent document 1. FIG.

Claims (2)

Dropping or placing a droplet of a melt containing a group III metal on the surface of a substrate or a group III nitride crystal, and supplying the alkali metal and nitrogen from the gas phase to the melt to dissolve the melt. A method for producing a Group III nitride crystal comprising forming a liquid and growing a Group III nitride comprising nitrogen and a Group III metal . 2. The method for producing a group III nitride crystal according to claim 1, wherein a predetermined pattern is formed with a melt on the substrate or the crystal surface of the group III nitride crystal, and the group III nitride is grown on the pattern. A method for producing a group III nitride crystal, comprising:

Images