JP2013070016A - Nitride semiconductor crystal growth device and growth method of the same - Google Patents

Abstract

A film of a group III nitride semiconductor is efficiently generated on a substrate and the uniformity of the generated film is improved.
A nitride semiconductor crystal growth apparatus includes a nitrogen-containing gas supply port, a Group 3 metal-containing gas supply port, and a catalyst material that decomposes the nitrogen-containing gas to generate active species. The catalyst material 1 is provided inside the nitrogen-containing gas supply port 8 or the like, and the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 are all facing the substrate surface.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor manufacturing apparatus for growing a compound semiconductor, and more particularly to a semiconductor manufacturing apparatus suitable for manufacturing a vapor phase epitaxial growth wafer of a group III nitride semiconductor.

  Nitride semiconductors using Group III metals such as GaN, AlN and InN have a wide band gap from 1.9 eV to 6.2 eV, so that light emitting diodes, laser diodes, etc. that cover the entire visible range from the ultraviolet region can be used. It is a promising semiconductor as a light emitting element material. In recent years, the nitride semiconductor is a material that is expected to be put to practical use in solar cells, power devices and the like in addition to light-emitting elements. In particular, a material such as GaN or InGaN has been put into practical use as a blue light-emitting element material, and development of a high-quality material and a high-efficiency growth method and growth apparatus is expected.

  As a method for growing the nitride semiconductor, a metal organic chemical vapor deposition (hereinafter referred to as “MOCVD”) is generally well known. Another name for MOCVD is MOVPE (Metal Organic Vapor Phase Epitaxy).

  An example of the configuration of a conventional vertical MOCVD apparatus used for the MOCVD method will be described as follows. In a conventional vertical MOCVD apparatus, a gas pipe for introducing a reaction gas and a carrier gas from a gas supply source to a growth chamber inside the reaction furnace is connected, and the growth chamber inside the reaction furnace is connected to the growth chamber. A gas supply mechanism provided with gas discharge holes for introducing reaction gas and carrier gas into the chamber is installed as a gas introduction part.

  In addition, a susceptor for placing a substrate is installed in the lower part of the growth chamber. The susceptor includes a heater for heating the substrate, and is rotatable about an axis of rotation by an actuator.

  Furthermore, a gas exhaust unit for exhausting the gas in the growth chamber to the outside is installed at the lower part of the reactor. The gas exhaust unit is connected to an exhaust gas treatment device for rendering the exhausted gas harmless via a purge line.

  When growing a compound semiconductor crystal in the vertical MOCVD apparatus having the above configuration, first, a substrate is placed on a susceptor, the susceptor is rotated, and the substrate is heated to a predetermined temperature by a heater. Thereafter, a reaction gas and a carrier gas (inert gas) are introduced into the growth chamber from the gas discharge holes provided in the gas supply mechanism.

  As described above, the MOCVD method is a method in which an organic metal gas is introduced into a growth chamber together with a carrier gas and heated to cause a gas phase reaction on a predetermined substrate, thereby growing a compound semiconductor crystal on the substrate. In the growth of compound semiconductor crystals using the MOCVD method, there is always a high demand for how to secure the maximum yield and production capacity while reducing costs while improving the quality of compound semiconductor crystals. ing.

When GaN or the like is grown on a substrate, ammonia gas (NH ₃ ) is generally used as a nitrogen source. However, since NH ₃ is known to be hardly decomposable, it is necessary to supply a very excessive amount of NH ₃ with respect to a Ga source (for example, trimethyl gallium) for the growth of the substrate. Efficient. Further, in order to decompose NH ₃ on the substrate surface, it is necessary to heat the substrate to a high temperature of usually about 1000 ° C. However, this heating causes a problem in the growth of GaN, InGaN, etc. that hinders the growth of the substrate such as crystallinity degradation or phase separation due to thermal desorption of nitrogen from the substrate surface.

Therefore, a method for supplying NH ₃ and reacting efficiently on the substrate under a certain low temperature condition has been studied. For example, Patent Document 1 discloses a method using a cracking cell. Patent Document 2 discloses a method of heating and heating a tungsten mesh to decompose and supply NH ₃ .

JP-A-4-74858 (published on March 10, 1992) JP 2008-56499 A (published March 13, 2008)

In Patent Document 1, in order to form a nitride film, the pressure needs to be in a vacuum state of 10 ⁻⁴ (Torr) or less. However, in the usual MOCVD, since the growth conditions of several Torr to several hundred Torr are used from the viewpoint of securing the growth rate, the above technique is difficult to put into practical use.

  On the other hand, in Patent Document 2, it is necessary to heat the tungsten mesh to 1000 ° C. or higher, and there is a concern about the temperature rise of the growth substrate. In particular, it is difficult to apply it to film formation of InGaN or the like that dislikes substrate temperature rise. In order to improve productivity, it is preferable to grow a large substrate and a plurality of substrates at the same time. However, Patent Documents 1 and 2 disclose specific methods for uniformly growing a large substrate and a plurality of substrates. Not presented. Therefore, it is difficult to put the metal nitride film formation using the above technique into practical use.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for efficiently and uniformly generating a group III nitride semiconductor film on a substrate.

  In order to solve the above-described problems, a nitride semiconductor crystal growth apparatus according to the present invention is a nitride semiconductor crystal growth apparatus for forming a group III nitride semiconductor film on a substrate, and a nitrogen-containing gas is supplied onto the substrate. A nitrogen-containing gas supply port for supplying to the substrate, a Group 3 metal-containing gas supply port for supplying a Group 3 metal-containing gas onto the substrate, and a catalyst material that decomposes the nitrogen-containing gas to generate active species. The catalyst material is provided inside or at the end of the nitrogen-containing gas supply port, and both of the nitrogen-containing gas supply port and the group 3 metal-containing gas supply port are aligned with the substrate surface of the substrate. It is characterized by being.

  According to the said structure, the catalyst material which decomposes | disassembles nitrogen-containing gas and produces | generates an active species is provided in the inside or edge part of a nitrogen-containing gas supply port. Therefore, a lot of nitrogen-containing gas can be brought into contact with the catalyst material. Since many nitrogen-containing gases are decomposed and activated, there is an effect that a group III nitride semiconductor film can be efficiently generated on the substrate.

  Furthermore, the catalyst material is provided inside or at the end of the nitrogen-containing gas supply port, and is not provided between the substrate and the nitrogen-containing gas supply port as in Patent Document 2. Therefore, even when the nitrogen-containing gas supply port and the Group 3 metal-containing gas supply port are both directly facing the substrate surface of the substrate, the Group 3 metal-containing gas supplied from the Group 3 metal-containing gas supply port is It can be configured not to touch the catalyst material. That is, since the adhesion of the Group 3 metal-containing gas to the catalyst material can be prevented, the activation of the nitrogen-containing gas by the catalyst material can be maintained, and the Group 3 nitride semiconductor film can be efficiently formed on the substrate. There is an effect that it can be generated. Furthermore, when the film is formed in a state where the Group 3 metal-containing gas does not touch the catalyst material, the Group 3 nitride semiconductor layer having high crystallinity is compared with the case where the Group 3 metal-containing gas touches the catalyst material. There exists an effect that it can form on a board | substrate.

  Since both the nitrogen-containing gas supply port and the Group 3 metal-containing gas supply port face the substrate surface of the substrate, the nitrogen-containing gas and the Group 3 metal-containing gas are uniformly supplied to the substrate. Can do. Therefore, there is an effect that the uniformity of the generated group III nitride semiconductor layer can be improved.

  In addition, by installing a catalyst material inside or at the end of the nitrogen-containing gas supply port connected to the reaction chamber, the distance that the active species move after the generation of the active species is shortened, so that more nitrogen-containing gas can be stored. It can be supplied to the substrate in an active state. At this time, the Group 3 metal-containing gas is supplied into the reaction chamber from a supply port different from the nitrogen-containing gas. Therefore, it is possible to avoid a problem that a film forming reaction occurs in the supply port or on the catalyst material before the gas reaches the substrate. Thereby, consumption of the material which does not contribute to the film-forming on a board | substrate, and attenuation | damping of the catalyst effect resulting from the film-forming on a catalyst material can be prevented.

  As described above, according to the above configuration, a group III nitride semiconductor film can be efficiently and uniformly formed on a substrate.

  The nitride semiconductor crystal growth apparatus according to the present invention preferably includes a catalyst heating means for heating the catalyst material.

  According to the above configuration, since the catalyst material is heated, the catalyst material is more activated. Therefore, there is an effect that the active species can be efficiently generated by bringing the nitrogen-containing gas into contact with the more activated catalyst material. Thus, for example, even when the substrate temperature is set to a low temperature, the catalyst material efficiently decomposes and activates the nitrogen-containing gas, so that a group III nitride semiconductor layer having excellent crystallinity is grown on the substrate. There is an effect that can be.

  The nitride semiconductor crystal growth apparatus according to the present invention preferably includes a cooling means for cooling the group III metal-containing gas supply port.

  In the case where the nitride semiconductor growth apparatus is provided with catalyst overheating means, the Group 3 metal-containing gas supply port and the Group 3 metal-containing gas may be heated by heat from the catalyst heating means. At this time, the Group 3 metal may be deposited in the Group 3 metal-containing gas supply port due to heat.

  However, according to said structure, since the group 3 metal containing gas supply port is cooled using the cooling means, the group 3 metal containing gas is not heated more than necessary by the heat of the catalyst heating means. Therefore, the Group 3 metal-containing gas is not heated by the heat of the catalyst heating means, and it is possible to prevent the Group 3 metal from being deposited at the Group 3 metal-containing gas supply port.

  The nitride semiconductor crystal growth apparatus according to the present invention preferably includes a plurality of the nitrogen-containing gas supply ports and the group III metal-containing gas supply ports.

  According to the above configuration, since the Group 3 metal-containing gas supplied from the Group 3 metal-containing gas supply port can be configured not to touch the catalyst material, the plurality of supply ports are all connected to the substrate surface of the substrate. Can be paired. By providing a plurality of supply ports, each source gas can be supplied over a wide range and evenly. Therefore, when processing a large area substrate or a plurality of substrates, an effect is obtained that the group III nitride semiconductor layer can be formed more uniformly.

  In the nitride semiconductor crystal growth apparatus according to the present invention, the nitrogen-containing gas supply port and the Group 3 metal-containing gas supply port face the substrate and are adjacent to each other in a plane having a larger area than the substrate. It is preferable that it is disposed.

  According to the above configuration, the nitrogen-containing gas and the Group 3 metal-containing gas can be discharged uniformly to the substrate. Therefore, even when the apparatus is enlarged so as to be compatible with a large substrate or a plurality of substrates, the uniformity of the group III nitride semiconductor layer to be formed can be ensured over a wide range.

  The nitride semiconductor crystal growth apparatus according to the present invention is arranged such that the nitrogen-containing gas supply port and the Group 3 metal-containing gas supply port discharge the nitrogen-containing gas and the Group 3 metal-containing gas in a shower shape. More preferably.

  According to the above configuration, the nitrogen-containing gas and the Group 3 metal-containing gas can be discharged in a shower shape. Therefore, substantially the same amount of source gas can be uniformly discharged from the plurality of nitrogen-containing gas supply ports and the plurality of Group 3 metal-containing gas supply ports facing the substrate. Therefore, there is an effect that the in-plane composition distribution of the group III nitride semiconductor layer can be made more uniform even in a large area.

  In the nitride semiconductor crystal growth apparatus according to the present invention, the pressure in the reaction chamber in which the substrate is stored is preferably 10 Torr or more and 760 Torr.

  According to the said structure, there exists an effect that the crystallinity of a group III nitride semiconductor layer can be improved.

According to the above configuration, it is not necessary to set the pressure in a vacuum state (about 10 ⁻⁴ Torr), and therefore, there is an effect that it is suitable for practical use from the viewpoint of the growth rate.

  The nitride semiconductor crystal growth apparatus according to the present invention preferably further includes a rotating means for rotating the substrate.

  According to the above configuration, since the substrate can be rotated, there is an effect that a uniform group III nitride semiconductor layer can be formed.

  In the nitride semiconductor crystal growth apparatus according to the present invention, the nitrogen-containing gas preferably contains ammonia.

  According to the said structure, there exists an effect that the hardly decomposable gas like ammonia can also be efficiently decomposed | disassembled and activated. Therefore, ammonia can be used as a nitrogen source for forming the group III nitride semiconductor layer on the substrate.

  The nitride semiconductor crystal growth apparatus according to the present invention preferably further includes a substrate heating means for heating the substrate to 400 ° C. or higher and 950 ° C. or lower.

  According to the said structure, there exists an effect that the nitrogen containing gas which is not activated by heating a board | substrate can be decomposed | disassembled activated on a board | substrate.

  Moreover, since radiant heat is generated when the substrate heating means heats the substrate, the radiant heat can heat the catalyst material. That is, since the catalyst material is heated and activated by radiant heat, there is an effect that the nitrogen-containing gas can be decomposed and activated more efficiently.

  In the nitride semiconductor crystal growth apparatus according to the present invention, the catalyst material is selected from a group consisting of Pt, W, Mo, Ni and Fe, or a group consisting of Pt, W, Mo, Ni and Fe. It is preferable that the material contains at least one of the above.

  According to the said structure, there exists an effect that nitrogen-containing gas can be decompose | disassembled efficiently by using catalyst materials, such as Pt, W, Mo, Ni, and Fe.

  In the nitride semiconductor crystal growth apparatus according to the present invention, the group III nitride semiconductor is preferably a group III nitride semiconductor selected from the group consisting of GaN, AlN, InN, InGaN, AlGaN, and InAlGaN.

  According to the above configuration, a substrate having a group III nitride semiconductor layer such as GaN, AlN, InN, InGaN, AlGaN, InAlGaN or the like having few nitrogen vacancies and crystal defects can be obtained. Therefore, the effect that a higher quality semiconductor material can be obtained is produced.

  The nitride semiconductor crystal growth reaction according to the present invention is a nitride semiconductor crystal growth method for forming a group III nitride semiconductor film on a substrate, the nitrogen-containing gas supply port facing the substrate surface of the substrate A gas supply step of supplying a nitrogen-containing gas onto the substrate through the substrate and supplying a group III metal-containing gas onto the substrate through a group III metal-containing gas supply port facing the substrate surface of the substrate And a catalyst material for decomposing the nitrogen-containing gas to generate active species is installed inside or at the end of the nitrogen-containing gas supply port.

  According to said method, there exists an effect equivalent to the nitride semiconductor crystal growth apparatus concerning this invention.

  In the nitride semiconductor crystal growth reaction according to the present invention, in the gas supply step, it is preferable to heat the catalyst material and cool the group III metal-containing gas supply port.

  According to the above method, since the catalyst material is heated, the catalyst material is more activated. Therefore, there is an effect that the active species can be efficiently generated by bringing the nitrogen-containing gas into contact with the more activated catalyst material. Thus, for example, even when the substrate temperature is set to a low temperature, the catalyst material efficiently decomposes and activates the nitrogen-containing gas, so that a group III nitride semiconductor layer having excellent crystallinity is grown on the substrate. There is an effect that can be.

  Furthermore, since the group 3 metal-containing gas supply port is cooled using the cooling means, the group 3 metal-containing gas is not heated more than necessary. Therefore, even when the catalyst material is heated, the Group 3 metal-containing gas is not heated, and the Group 3 metal can be prevented from being deposited at the Group 3 metal-containing gas supply port.

  A nitride semiconductor crystal growth apparatus according to the present invention is a nitride semiconductor crystal growth apparatus for forming a group III nitride semiconductor film on a substrate, and supplies a nitrogen-containing gas onto the substrate. And a Group 3 metal-containing gas supply port for supplying the Group 3 metal-containing gas onto the substrate, and a catalytic material that decomposes the nitrogen-containing gas to generate active species, the catalyst material comprising: The nitrogen-containing gas supply port is provided inside or at the end, and both the nitrogen-containing gas supply port and the Group 3 metal-containing gas supply port are directly facing the substrate surface of the substrate. Since it is a nitride semiconductor crystal growth apparatus, it is possible to generate a group III nitride semiconductor film efficiently and uniformly on a substrate.

  The nitride semiconductor crystal growth method according to the present invention is a nitride semiconductor crystal growth method for forming a group III nitride semiconductor film on a substrate, the nitrogen-containing gas facing the substrate surface of the substrate. A gas that supplies a nitrogen-containing gas onto the substrate through a supply port, and supplies a Group 3 metal-containing gas onto the substrate through a Group 3 metal-containing gas supply port that faces the substrate surface of the substrate. A nitride semiconductor comprising a supply step, wherein a catalyst material that decomposes the nitrogen-containing gas to generate active species is installed in or at the end of the nitrogen-containing gas supply port Since it is a crystal growth method, it is possible to efficiently and uniformly generate a group III nitride semiconductor film on the substrate.

1 is a schematic diagram of a nitride semiconductor crystal growth apparatus according to an embodiment of the present invention. It is sectional drawing which shows the variation of a structure of a catalyst material and a nitrogen-containing gas supply port. 1 is a schematic diagram of a nitride semiconductor crystal growth apparatus according to an embodiment of the present invention. 1 is a schematic diagram of a nitride semiconductor crystal growth apparatus according to an embodiment of the present invention. It is the schematic diagram which expanded a part of nitride semiconductor crystal growth apparatus concerning one embodiment of the present invention. It is a schematic diagram which shows the variation of arrangement | positioning of a nitrogen containing gas supply port and a group 3 metal containing gas supply port. It is a graph which shows the result of the ammonia decomposition | disassembly effect experiment by a catalyst material. It is the schematic diagram which expanded a part of nitride semiconductor crystal growth apparatus concerning one embodiment of the present invention.

[First Embodiment]
(Nitride semiconductor crystal growth equipment)
FIG. 1 shows a nitride semiconductor crystal growth apparatus 100 according to an embodiment (first embodiment) of the present invention. As shown in FIG. 1, the nitride semiconductor crystal growth apparatus 100 includes a catalyst material 1, a heater (catalyst heating means) 2, a susceptor 4, a substrate heater (substrate heating means) 5, a plurality of nitrogen-containing gas supply ports 8, A plurality of Group 3 metal-containing gas supply ports 9, exhaust ports 12 and a rotation mechanism (rotation means) 13 are provided.

  The nitride semiconductor crystal growth apparatus 100 is an apparatus for forming a group III nitride semiconductor film on a substrate. A group III nitride semiconductor is a metal nitride formed from a group III metal (Al, Ga, In, etc.) and nitrogen. Examples of the group III nitride semiconductor include metal nitrides such as GaN, AlN, InN, InGaN, AlGaN, and InAlGaN.

(substrate)
The substrate 3 is a substrate for forming a group III nitride semiconductor film.

(Susceptor)
The susceptor 4 is a table for placing the substrate 3 thereon.

(Reaction room)
The reaction chamber refers to the inside of the nitride semiconductor crystal growth apparatus 100. Further, it refers to a place where a group III nitride semiconductor film is formed.

(Nitrogen-containing gas)
The nitrogen-containing gas 6 is a source gas that becomes a nitrogen source of the group III nitride semiconductor. The nitrogen-containing gas 6 only needs to contain a gas containing nitrogen atoms. For example, the nitrogen-containing gas 6 may contain a nitrogen compound such as NH ₃ or N ₂ . Further, the nitrogen-containing gas 6 may further contain a gas other than the nitrogen compound, for example, H ₂ or the like.

(Nitrogen-containing gas supply port)
The nitrogen-containing gas supply port 8 is a gas supply means for discharging the nitrogen-containing gas 6 into the reaction chamber. A plurality of nitrogen-containing gas supply ports 8 are installed. Each nitrogen-containing gas supply port 8 faces the substrate 3. Thus, the nitrogen-containing gas 6 can be discharged from the direction perpendicular to the substrate surface with respect to the substrate 3.

(Catalyst material)
The catalyst material 1 is a catalyst for decomposing and activating the nitrogen-containing gas 6 to generate active species (radicals). The catalyst material 1 is attached to the inside of the nitrogen-containing gas supply port 8 or the end on the outlet side.

The nitrogen-containing gas 6 is decomposed and activated by contacting the catalyst material 1 attached to the nitrogen-containing gas supply port 8. For example, when NH ₃ is decomposed by the catalyst material 1, active species containing nitrogen such as NH ₂ , NH, and N are generated.

  The catalyst material 1 is not limited as long as it can decompose and activate the nitrogen-containing gas 6, but for example, simple substance such as Pt, W, Mo, Ni, Fe or the like, or Pt, W, Mo, Ni, Fe, etc. A material (alloy) containing at least one of Pt, W or Mo is preferable, and a material containing at least one of Pt, W or Mo is more preferable. Moreover, when the catalyst material 1 contains Fe, it is preferable to contain at least one of Pt, W, Mo, etc. in addition. Further, the activation effect increases as the installation area of the catalyst material 1 increases.

  FIGS. 2A to 2F are cross-sectional views showing variations in the configuration of the catalyst material 1 and the nitrogen-containing gas supply port 8. The catalyst material 1 and the nitrogen-containing gas supply port 8 can take any configuration as shown in the figure, for example. In addition, in FIG. 2, the heater 2 is abbreviate | omitted for description.

  In one example, as shown in FIG. 2A, a mesh-like catalyst material 1a can be installed inside the nitrogen-containing gas supply port 8 (a portion surrounded by the inner wall 8b). At this time, the catalyst material 1a is not particularly limited, but it is more preferable that the catalyst material 1a is disposed near the outlet of the nitrogen-containing gas supply port 8.

  In one example, as shown in FIG. 2B, a porous catalyst material 1 b may be installed inside the nitrogen-containing gas supply port 8. As the porous catalyst material 1b, for example, a honeycomb structure or the like can be taken. Further, the catalyst material 1 may be installed so that a porous structure is formed inside the nitrogen-containing gas supply port 8. For example, the catalyst material 1 may be formed and filled into the nitrogen-containing gas supply port 8 in a granular form, or the catalyst material 1 may be formed and filled in a metal wool shape such as steel wool. As in the example of FIG. 2A, the catalyst material 1 b is not particularly limited, but is preferably disposed near the outlet of the nitrogen-containing gas supply port 8.

  In one example, as shown in FIG. 2C, at least a part of the inner wall 8b of the nitrogen-containing gas supply port 8 may be coated with the catalyst material 1c.

  In one example, as shown in FIG. 2 (d), a mesh-shaped catalyst material 1 d may be installed at the end of the nitrogen-containing gas supply port 8 on the outlet side.

  In one example, as shown in FIG. 2 (e), a porous catalyst material 1 e may be provided at the end of the nitrogen-containing gas supply port 8 on the outlet side.

  In one example, as shown in FIG. 2F, the inner wall 8b of the nitrogen-containing gas supply port 8 may be formed of the catalyst material 1f.

  As described above, by installing the catalyst materials 1a to 1f in the nitrogen-containing gas supply port 8 or at the end on the outlet side, the catalyst materials 1a to 1f are supplied from the nitrogen-containing gas supply port 8. 6 can be efficiently decomposed and activated.

(Group 3 metal-containing gas)
The group 3 metal-containing gas 7 is a source gas that becomes a group 3 metal source of the group 3 nitride semiconductor. The group 3 metal-containing gas 7 is not limited as long as it contains a compound that is a gas at a relatively low temperature and contains a group 3 metal. For example, organic metals such as trimethylgallium (TMG) and trimethylindium (TMI) are used. It is preferable that gas is included. Further, N ₂ , H ₂ or the like may be contained as a carrier gas.

(Group 3 metal-containing gas supply port)
The group 3 metal-containing gas supply port 9 is a gas supply means for discharging the group 3 metal-containing gas 7 to the reaction chamber. The group 3 metal-containing gas supply port 9 is arranged so that the discharged group 3 metal-containing gas 7 does not touch the catalyst material 1. A plurality of Group 3 metal-containing gas supply ports 9 are provided.

  The group 3 metal-containing gas supply port 9 faces the substrate 3 in the same manner as the nitrogen-containing gas supply port 8. Thereby, the group 3 metal-containing gas 7 can be discharged from the direction perpendicular to the substrate surface to the substrate 3.

  Further, the plurality of nitrogen-containing gas supply ports 8 and the plurality of group III metal-containing gas supply ports 9 may be arranged alternately or may be arranged coaxially. In one embodiment, it is preferable that at least one group 3 metal-containing gas supply port 9 is arranged next to an arbitrary nitrogen-containing gas supply port 8.

  Further, a plurality of nitrogen-containing gas supply ports 8 and a plurality of group III metal-containing gas supply ports 9 may be arranged so as to discharge a source gas such as the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 in a shower shape. “Discharging the source gas in the form of a shower” means that the source gas discharged from each supply port is substantially the same amount, and that each source gas is discharged evenly to the substrate 3 facing to each other. . In order to uniformly discharge the source gas onto the substrate 3, it is preferable to keep the distance between the discharge ports constant.

(exhaust port)
The exhaust port 12 is for exhausting gases unnecessary for the reaction (for example, desorbed CH ₄ , carrier gas, unreacted nitrogen-containing gas, etc.). The exhaust port 12 is installed on the opposite side of each gas supply port with the susceptor 4 interposed therebetween.

(heater)
The heater 2 is a heating unit that heats the catalyst material 1. The heater 2 is attached inside or outside the nitrogen-containing gas supply port 8 so as to heat the catalyst material 1.

(Substrate heater)
The substrate heater 5 is a heating unit that heats the substrate 3. The substrate heater 5 is disposed inside the susceptor 4.

(Rotating mechanism)
The rotation mechanism 13 is for rotating the substrate 3 placed on the susceptor 4 when forming a group III nitride semiconductor film on the substrate 3. The rotation mechanism 13 is connected to the lower part of the susceptor 4.

(Growth method using nitride semiconductor crystal growth equipment)
Hereinafter, a method for growing a group III nitride semiconductor on the substrate 3 using the nitride semiconductor crystal growth apparatus 100 will be described.

  First, the substrate 3 is placed on the susceptor 4. Next, the substrate 3 is heated to a predetermined temperature by the substrate heater 5. Further, the pressure in the reaction chamber is set to a predetermined value.

  The pressure condition is preferably 0.1 Torr or more and 1520 Torr or less, and more preferably 10 Torr or more and 760 Torr or less, in order to improve the crystallinity of the group III nitride semiconductor layer. If it is 0.1 Torr or more, the reactivity is not significantly lowered and the crystal growth is not slowed, and if it is 1520 Torr or less, the safety of the apparatus is not impaired.

The temperature condition of the substrate 3 will be described. Since the catalyst material 1 efficiently decomposes and activates the nitrogen-containing gas 6, it is not necessary to raise the temperature of the substrate 3 in order to decompose the nitrogen-containing gas 6. For example, it is possible to grow a crystal such as InGaN on the substrate 3 at a low temperature of about 400 ° C. to 950 ° C. In particular, by heating the catalyst material 1 to 600 ° C. or higher, NH _{3 and the} like can be efficiently decomposed, so that the substrate temperature can be lowered. Further, the nitrogen-containing gas 6 that is not activated can be decomposed and activated by heating the substrate 3. Further, since the substrate heater 5 heats the substrate 3 and the susceptor 4 to generate radiant heat, the radiant heat can assist the heating and activation of the catalyst material 1 by the heater 2.

  When the group III nitride semiconductor is grown on the substrate 3, it is preferable to rotate the substrate 3 by the rotation mechanism 13. Moreover, as a preferable rotational speed, it is preferable that it is more than 0 rpm and 1500 rpm or less, and it is more preferable that they are 1 rpm or more and 300 rpm or less.

(Generation of active species)
First, the nitrogen-containing gas 6 supplied from a gas source (not shown) is discharged from the nitrogen-containing gas supply port 8 to the reaction chamber.

Then, by contacting the catalyst material 1 attached to the nitrogen-containing gas supply port 8, the nitrogen-containing gas 6 is decomposed and activated to generate active species. Hereinafter, the case where NH ₃ is contained in the nitrogen-containing gas 6 and NH ₃ is decomposed and activated will be described.

At this time, since the catalyst material 1 is heated by the heater 2, the decomposition reaction of NH ₃ on the catalyst material 1 is promoted. Further, the amount of decomposition of NH ₃ in the above catalyst material 1, in order to increase than the decomposition of NH ₃ in on substrate 3, the catalyst material 1 is preferably heated above 600 ° C.. On the other hand, the amount of decomposition of NH ₃ in the upper substrate 3 is made larger than the amount of decomposition of the NH ₃ in the above catalyst material 1, when the role of the catalyst material 1 to the auxiliary ones, the catalyst material 1 The heating may be about 100 ° C.

When NH ₃ is decomposed and activated as described above, active species containing nitrogen such as NH ₂ , NH, and N are generated.

(Reaction between active species and Group 3 metal-containing gas)
The Group 3 metal-containing gas 7 supplied from a gas source (not shown) is discharged from the Group 3 metal-containing gas supply port 9 to the reaction chamber. The group 3 metal-containing gas 7 finally forms a group III nitride semiconductor by reacting with the active species.

For example, when the group 3 metal-containing gas 7 contains an organometallic gas such as trimethylgallium (TMG) or trimethylindium (TMI), it reacts with an active species such as NH ₂ or NH, thereby producing TMG-NH _2. , TMG-NH, TMI-NH ₂ or TMI-NH.

In the generated compound, CH ₄ is desorbed, and finally nitrides such as GaN, InN, and InGaN are formed.

(Nitride semiconductor is formed on the substrate)
The compounds such as TMG-NH ₂ , TMG-NH, TMI-NH ₂ , and TMI-NH generated as described above can be separated from CH ₄ to reach the substrate 3 by GaN, InN. , Such as InGaN, and grows on the substrate 3.

(Effect of this embodiment)
In the present embodiment, since the catalyst material 1 is attached to the inside of the nitrogen-containing gas supply port 8 or the end portion on the outlet side, an effect that the hardly decomposable gas such as NH ₃ can be efficiently decomposed is obtained. . In the invention according to Patent Document 1, the pressure needs to be in a vacuum state (about 10 ⁻⁴ Torr), but in this embodiment, for example, a crystal can be grown on the substrate at a pressure of about 10 to 760 Torr. . Therefore, it is suitable for practical use from the viewpoint of growth rate. Further, in the invention according to Patent Document 2, it is necessary to heat the substrate surface at a high temperature of 1000 ° C. or higher, but in this embodiment, for example, crystals are formed on the substrate even at a low temperature of about 400 to 950 ° C. Can be grown. Therefore, problems such as crystallinity degradation and phase separation due to thermal desorption of nitrogen from the growth surface of the substrate are unlikely to occur.

In particular, when the catalyst material 1 is heated to 600 ° C. or higher, the effect of efficiently decomposing NH ₃ or the like and generating more active species is obtained. As a result, since nitrogen can be taken into the growth surface of the substrate 3 with high efficiency, nitrogen vacancies, crystal defects, and the like can be reduced.

In the present embodiment, since the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 are discharged only from the direction facing the substrate surface, the uniformity of the generated group III nitride semiconductor layer is improved. Can do. On the other hand, as disclosed in Patent Document 2, since active species such as NH ₂ , NH, and N that have been decomposed have a lifetime, if a gas is supplied from the lateral direction to the substrate 3, a large-area substrate or a plurality of substrates In-plane distribution occurs when processing the substrate. In the present embodiment, the catalyst material 1 is provided at the inside of the nitrogen-containing gas supply port 8 or at the end on the outlet side. For example, even if a plurality of supply ports are provided, nitrogen is contained only from the direction facing the substrate surface. The gas 6 and the Group 3 metal-containing gas 7 can be discharged.

  In addition, even when a plurality of supply ports are provided in this way, the Group 3 metal-containing gas 7 does not touch the catalyst material 1. That is, since the adhesion of the Group 3 metal-containing gas to the catalyst material can be prevented, the activation of the nitrogen-containing gas by the catalyst material can be maintained, and the Group 3 nitride semiconductor film can be efficiently formed on the substrate. Can be generated. Further, when the film is formed in a state in which the Group 3 metal-containing gas 7 does not touch the catalyst material 1, the Group 3 nitridation having higher crystallinity than the case where the Group 3 metal-containing gas 7 contacts the catalyst material 1. A physical semiconductor layer can be formed on the substrate.

  Further, by providing a plurality of supply ports, it is possible to more uniformly form the group III nitride semiconductor layer when processing a large area substrate or a plurality of substrates. In particular, since each supply port is arranged so as to discharge the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 in a shower shape, the same amount of the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 are obtained. It is possible to obtain an effect that the particles can be dispersed evenly. Therefore, the in-plane composition distribution of the group III nitride semiconductor layer can be made more uniform even in a large area.

  By arranging the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 alternately or coaxially, each source gas can be supplied uniformly, and a group III nitride semiconductor layer can be formed more uniformly. The effect that it can be obtained.

  By heating the substrate 3 with the substrate heater 5, the nitrogen-containing gas 6 can be decomposed also on the substrate 3. Further, the radiant heat generated by the heating of the substrate heater 5 can assist the heating and activation of the catalyst material 1 by the heater 2.

  In addition, by having a configuration in which the substrate 3 is rotated by the rotation mechanism 13, an effect that a uniform group III nitride semiconductor layer can be formed is obtained.

(Modification)
The nitride semiconductor crystal growth apparatus 100 according to the present embodiment may have a configuration in which the heater 2 is not provided, for example, as shown in FIG. Thus, the catalyst material 1 is heated by the radiant heat from the substrate 3 and the susceptor 4 even if no heating means for heating the catalyst material 1 is provided. Therefore, even when the heater 2 is not attached, the catalyst material 1 can be activated by radiant heat, so that a hardly decomposable gas such as NH ₃ can be efficiently decomposed. Radiant heat is generated when the substrate heater 5 heats the substrate 3 and the susceptor 4.

[Second Embodiment]
A second embodiment of the present invention will be described. The nitride semiconductor crystal growth apparatus according to this embodiment is different from the nitride semiconductor crystal growth apparatus according to the first embodiment in that it mainly includes a cooling means for cooling the Group 3 metal-containing gas supply port. . The nitride semiconductor crystal growth apparatus according to the present embodiment includes the cooling means, so that the Group 3 metal is precipitated in the Group 3 metal-containing gas supply port by the heat from the heater for heating the catalyst. Can be avoided successfully. Hereinafter, the details of the second embodiment will be described with reference to FIGS. Note that the same reference numerals as those in the first embodiment denote the same or corresponding parts.

  FIG. 4 is a diagram schematically showing a schematic configuration of the nitride semiconductor crystal growth apparatus 200 according to the present embodiment. As shown in FIG. 4, the nitride semiconductor crystal growth apparatus 200 includes a reaction furnace 20 that isolates the inside from the atmosphere side, and a reaction chamber 30 is provided inside the reaction furnace 20. The reaction chamber 30 includes a susceptor (substrate holding unit) 4 on which a substrate (substrate to be processed) 3 is placed.

  The susceptor 4 is provided at one end of a rotation transmitting portion of the rotation mechanism (rotating means) 13 and is rotatable. A substrate heater (substrate heating means) 5 for heating the substrate 3 is provided below the susceptor 4.

  A gas supply mechanism 10 is disposed at the top of the reaction furnace 20. The gas supply mechanism 10 includes a plurality of nitrogen-containing gas supply ports 8 for supplying the nitrogen-containing gas 6 and a plurality of group III metal-containing gas supply ports 9 for supplying the group III metal-containing gas 7. The nitrogen-containing gas supply port 8 and the Group 3 metal-containing gas supply port 9 are disposed adjacent to each other in a plane facing the substrate. The gas supply mechanism 10 also includes a catalyst material 1, a heater (catalyst heating means) 2, a nitrogen-containing gas supply source 14, a group 3 metal-containing gas supply source 15, a cooling mechanism (cooling means) 17, and a heat insulating material 18. ing.

  The nitrogen-containing gas 6 and the Group 3 metal-containing gas 7 can be the same as those in the first embodiment. When the nitride semiconductor crystal is formed on the substrate 3, the nitrogen-containing gas 6 supplied from the nitrogen-containing gas supply source 14 reacts from a plurality of nitrogen-containing gas supply ports 8 provided in the gas supply mechanism 10. A plurality of Group 3 metal-containing gas supply ports, which are supplied into the chamber 30 and supplied from the Group 3 metal-containing gas supply source 15, are arranged in the gas supply mechanism 10. 9 is fed into the reaction chamber 30. The catalyst material 1 heated by the heater 2 is provided inside the nitrogen-containing gas supply port 8, and the nitrogen-containing gas 6 passing through the nitrogen-containing gas supply port 8 is activated by the catalyst material 1. Is introduced into the reaction chamber 30.

  Here, the structure in which the nitrogen-containing gas 6 and the Group 3 metal-containing gas 7 are supplied from different supply ports to the reaction chamber 30 is such that the nitrogen-containing gas 6 activated by the catalyst material 1 is in the gas supply mechanism 10 or the catalyst material. It is also important for preventing unintended gas phase reactions from occurring on the top of 1 and the like. However, since the nitrogen-containing gas 6 and the Group 3 metal-containing gas 7 are introduced from different supply ports 8 and 9, there is a possibility that the gas reaching the substrate 3 is unevenly distributed. Therefore, it is preferable that the rotation mechanism 13 rotates the substrate 3 (or the susceptor 4) during the film forming process. In this case, the rotation speed of the substrate 3 is preferably more than 0 rpm and not more than 1500 rpm.

  The substrate 3 held on the susceptor 4 is heated to a high temperature by the substrate heater 6. When the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 introduced into the reaction chamber 30 reach the high temperature substrate 3, the gas phase reaction is promoted, and a nitride semiconductor thin film is formed on the substrate 3. The nitride semiconductor thin film to be formed is the same as in the first embodiment.

  The reaction gas that has passed over the substrate to be processed 3 is discharged from the exhaust port 7 provided in the reaction furnace 20, and is rendered harmless by an exhaust gas treatment apparatus (not shown).

  The pressure condition during film formation is preferably 0.1 Torr or more and 1520 Torr or less. If it is 0.1 Torr or more, the reactivity is not significantly lowered and the crystal growth is not slowed, and if it is 760 Torr or less, the safety of the apparatus is not impaired.

  Next, a detailed configuration of the gas supply mechanism 10 will be described. FIG. 8 is a cross-sectional view schematically showing the configuration of the gas supply mechanism 10, enlarging the portion A of FIG. 4.

  The plurality of nitrogen-containing gas supply ports 8 and the plurality of group III metal-containing gas supply ports 9 are arranged adjacent to each other and alternately arranged. At this time, the distance between the two is preferably as short as possible. Further, it is preferable that the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 appear alternately with respect to the rotation direction of the substrate 3. That is, it is preferable that when the substrate 3 is rotated, the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 appear alternately right above an arbitrary position of the substrate 3. This is because the nitrogen-containing gas 6 and the group 3 metal-containing gas 7 are caused when the distance between the two supply ports is too large, or when the nitrogen-containing gas supply ports 8 or the group 3 metal-containing gas supply ports 9 are partially concentrated. This is because the mixing of the above becomes insufficient, which may adversely affect the composition and uniformity of the produced nitride semiconductor.

  The shapes of the nitrogen-containing gas supply port 8 and the Group 3 metal-containing gas supply port 9 are not particularly limited, and may be various shapes such as a slit shape, a shower shape, or a combination thereof. 6A to 6D show schematic configuration examples of the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 provided in the gas supply mechanism 10 as viewed from the substrate 3 side. Note that FIG. 6 is merely a configuration example of the supply mechanism, and the configurations of the nitrogen-containing gas supply port 8 and the Group 3 metal-containing gas supply port 9 are not limited to those of FIG. The configuration in which the plurality of nitrogen-containing gas supply ports 8 and the plurality of Group 3 metal-containing gas supply ports 9 are alternately arranged adjacent to each other and the configurations shown in FIGS. The embodiment can also be suitably employed.

  The nitrogen-containing gas supply port 8 and the Group 3 metal-containing gas supply port 9 have an area larger than that of the substrate 3 and are disposed in a plane facing the substrate 3, and from a direction perpendicular to the surface of the substrate 3. Each source gas is discharged. Thereby, the nitrogen-containing gas supply port 8 and the group 3 metal-containing gas supply port 9 can be supplied uniformly to the substrate 3.

  The catalyst material 1 and the heater 2 can be provided similarly to the first embodiment. 4 and 5, the catalyst material 1 is coated on the inside of the outlet side of the nitrogen-containing gas supply port 8. Further, as shown in FIG. 8, the catalyst material 1 may be installed in a mesh shape inside the nitrogen-containing gas supply port 8. By installing the catalyst material 1 as shown in FIG. 8, the installation surface area of the catalyst material 1 is increased compared to the case where the catalyst material 1 is arranged as shown in FIGS. 4 and 5, and a greater activation effect can be expected. Further, as another variation that can be expected to have the same effect, a method in which the catalyst material 1 having a porous shape is installed inside is also conceivable. As the catalyst material having a porous shape here, for example, a catalyst material having a honeycomb structure, a method of filling a plurality of granular catalyst materials, a catalyst material formed in a wool shape such as steel wool, etc. Can be considered. Further, the catalyst material 1 may be provided inside the nitrogen-containing gas supply port 8 or may be provided at the outlet end. However, since it is possible to prevent the activation ability of the nitrogen-containing gas from decreasing due to the adhesion of the group 3 metal-containing gas without touching the group 3 metal-containing gas, a catalyst material is placed inside the nitrogen-containing gas supply port 8. It is preferable to arrange.

(Cooling mechanism)
A cooling mechanism 17 is disposed around the group 3 metal-containing gas supply port 9. The cooling mechanism 17 may be any mechanism that can cool the Group 3 metal-containing gas supply port 9, and a known cooling mechanism can be used. For example, as shown in FIG. 4, a vaporization compression type or vaporization absorption type cooling mechanism that circulates a refrigerant around the group 3 metal-containing gas supply port 9 can be used. A cooling mechanism using the Peltier effect may be used.

  Here, when there is no cooling mechanism 17, the heating of the heater 2 that heats the catalyst material 1 heats the Group 3 metal-containing gas flowing in the adjacent Group 3 metal-containing gas supply port 9, and supplies the Group 3 metal-containing gas. It is assumed that the Group 3 metal-containing gas 7 is decomposed in the port 9 and in the Group 3 metal-containing gas supply pipe, and the Group 3 metal is deposited in the Group 3 metal-containing gas supply port 9 and the supply pipe. The cooling mechanism 17 cools the group 3 metal-containing gas supply port 9 to reduce the influence of heating of the heater 2 on the group 3 metal-containing gas 7 flowing in the adjacent group 3 metal-containing gas supply port 9. .

  In addition, it is preferable to provide a heat insulating material 18 between the heater 2 and the cooling mechanism 17 so that the heater 2 and the cooling mechanism 17 influence each other and do not adversely affect each other's ability. A known heat insulating material can be used as the heat insulating material 18.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

The experimental results regarding the catalytic effect are shown in FIG. In this experiment, a nitrogen-containing gas (NH ₃ + H ₂ , N ₂ ) was introduced onto the sapphire substrate through a nozzle provided with a catalyst material or a nozzle not provided with a catalyst material, and the amounts of nitriding on the substrate surface were compared. Pt was used as the catalyst material. The amount of nitriding was measured using XPS (X-ray photoelectron spectroscopy). In this experiment, the distribution of the nitrogen content in the depth direction was measured from the relationship between the number of sputterings and the nitriding amount. As shown in FIG. 7, when a nitrogen-containing gas is introduced using a nozzle provided with a Pt catalyst material, the amount of nitridation on the substrate surface is increased as compared with the case where a nozzle not provided with a Pt catalyst material is used. That is, it was found that more activated nitrogen source reached the substrate surface. From this, it was confirmed that the decomposition of the nitrogen-containing gas was promoted by the catalyst material provided in the nozzle (nitrogen-containing gas supply port).

  The present invention can be used in the field of manufacturing semiconductor materials, in particular, light emitting element materials such as light emitting diodes and laser diodes.

1 catalyst material 2 heater (catalyst heating means)
3 Substrate 4 Susceptor 5 Substrate heater (Substrate heating means)
6 Nitrogen-containing gas 7 Group 3 metal-containing gas 8 Nitrogen-containing gas supply port 9 Group 3 metal-containing gas supply port 10 Gas supply mechanism 12 Exhaust port 13 Rotating mechanism (rotating means)
14 Nitrogen-containing gas supply source 15 Group 3 metal-containing gas supply source 17 Cooling mechanism (cooling means)
18 Heat insulating material 20 Reactor 30 Reaction chamber 100, 200 Nitride semiconductor crystal growth apparatus

Claims (14)

A nitride semiconductor crystal growth apparatus for forming a group III nitride semiconductor film on a substrate,
A nitrogen-containing gas supply port for supplying a nitrogen-containing gas onto the substrate;
A Group 3 metal-containing gas supply port for supplying a Group 3 metal-containing gas onto the substrate;
A catalytic material that decomposes the nitrogen-containing gas to generate active species, and
The catalyst material is provided inside or at the end of the nitrogen-containing gas supply port,
The nitrogen-containing gas supply port and the group III metal-containing gas supply port both face the substrate surface of the substrate.   2. The nitride semiconductor crystal growth apparatus according to claim 1, further comprising catalyst heating means for heating the catalyst material.   The nitride semiconductor crystal growth apparatus according to claim 2, further comprising a cooling unit that cools the Group 3 metal-containing gas supply port.   4. The nitride semiconductor crystal growth apparatus according to claim 1, further comprising a plurality of the nitrogen-containing gas supply ports and the group 3 metal-containing gas supply ports. 5.   The nitrogen-containing gas supply port and the group III metal-containing gas supply port are arranged to face each other and to be adjacent to each other in a plane having an area larger than that of the substrate. 4. The nitride semiconductor crystal growth apparatus according to 4.   6. The nitrogen-containing gas supply port and the group III metal-containing gas supply port are arranged so as to discharge the nitrogen-containing gas and the group III metal-containing gas in a shower shape. The nitride semiconductor crystal growth apparatus described in 1.   7. The nitride semiconductor crystal growth apparatus according to claim 1, wherein a pressure of a reaction chamber in which the substrate is stored is 10 Torr or more and 760 Torr or less.   The nitride semiconductor crystal growth apparatus according to claim 1, further comprising a rotating unit that rotates the substrate.   The nitride semiconductor crystal growth apparatus according to claim 1, wherein the nitrogen-containing gas contains ammonia.   The nitride semiconductor crystal growth apparatus according to claim 1, further comprising substrate heating means for heating the substrate to 400 ° C. or more and 950 ° C. or less.   The catalyst material is a material containing at least one selected from the group consisting of Pt, W, Mo, Ni and Fe, or the group consisting of Pt, W, Mo, Ni and Fe. The nitride semiconductor crystal growth apparatus according to any one of claims 1 to 10.   12. The group III nitride semiconductor according to claim 1, wherein the group III nitride semiconductor is a group III nitride semiconductor selected from the group consisting of GaN, AlN, InN, InGaN, AlGaN, and InAlGaN. Nitride semiconductor crystal growth equipment. A nitride semiconductor crystal growth method for forming a group III nitride semiconductor film on a substrate,
A nitrogen-containing gas is supplied onto the substrate via a nitrogen-containing gas supply port facing the substrate surface of the substrate, and via a Group III metal-containing gas supply port facing the substrate surface of the substrate. Including a gas supply step of supplying a Group 3 metal-containing gas onto the substrate;
A nitride semiconductor crystal growth method, characterized in that a catalyst material that decomposes the nitrogen-containing gas to generate active species is installed inside or at the end of the nitrogen-containing gas supply port.   The nitride semiconductor crystal growth method according to claim 13, wherein, in the gas supply step, the catalyst material is heated and the group III metal-containing gas supply port is cooled.