阅读说明：本技术 Iii族氮化物基板的制造装置和制造方法 (Apparatus and method for manufacturing group III nitride substrate ) 是由 久保田芳宏 永田和寿 于 2020-03-24 设计创作，主要内容包括：本发明的III族氮化物基板的制造装置具备：在反应容器(1)内保持晶种(2)并旋转的自转基座(3),对晶种(2)进行加热的加热工具(9),配置收纳自转基座(2)并旋转的公转基座(4),相对于公转基座(4)的旋转轴的轴方向以规定的倾斜度喷出III族元素的氯化物气体的第一气体喷出口(6)、喷出含氮气体的第二气体喷出口(7)以及从第一气体喷出口(6)和第二气体喷出口(7)之间喷出惰性气体的第三气体喷出口(8),和排出气体的排气工具(5)。根据本发明,可提供可得到均匀且良好的III族氮化物结晶基板的制造装置和制造方法。(The apparatus for manufacturing a group III nitride substrate according to the present invention includes: a rotation base (3) which holds and rotates a seed crystal (2) in a reaction vessel (1), a heating tool (9) which heats the seed crystal (2), a revolution base (4) which accommodates and rotates the rotation base (2), a first gas ejection port (6) which ejects a chloride gas of a group III element at a predetermined inclination with respect to the axial direction of the rotation axis of the revolution base (4), a second gas ejection port (7) which ejects a nitrogen-containing gas, a third gas ejection port (8) which ejects an inert gas from between the first gas ejection port (6) and the second gas ejection port (7), and an exhaust tool (5) which exhausts the gas. According to the present invention, a manufacturing apparatus and a manufacturing method capable of obtaining a uniform and good group III nitride crystal substrate can be provided.)

1. An apparatus for manufacturing a group III nitride substrate, comprising

A self-rotating susceptor for holding a seed crystal and rotating in the reaction vessel,

a heating means for heating the seed crystal,

a revolution base for accommodating the rotation base and rotating,

a first gas ejection port for ejecting a chloride gas of a group III element at a predetermined inclination with respect to an axial direction of a rotation axis of the revolving susceptor, a second gas ejection port for ejecting a nitrogen-containing gas, and a third gas ejection port for ejecting an inert gas from between the first gas ejection port and the second gas ejection port, and

an exhaust tool for exhausting gas.

2. The apparatus for manufacturing a group III nitride substrate according to claim 1, wherein the third gas ejection port surrounds the first gas ejection port, and the second gas ejection port surrounds the third gas ejection port and is formed as a concentric multi-tube.

3. The apparatus for manufacturing a group III nitride substrate according to claim 1 or 2, wherein the inclination is selected from a range of 5 ° or more and 85 ° or less.

4. The apparatus for producing a group III nitride substrate according to any one of claims 1 to 3, wherein an inner wall of the reaction vessel is coated with a material that does not react with the gases or reaction products of the gases ejected from the first gas ejection port, the second gas ejection port, and the third gas ejection port.

5. The apparatus for manufacturing a group III nitride substrate according to any one of claims 1 to 4, further comprising a pressure adjusting means for adjusting the inside of the reaction vessel to a negative pressure that is lower than the atmospheric pressure.

6. A method for producing a group III nitride substrate, characterized by holding a seed crystal on a spin susceptor rotating in a reaction vessel,

the seed crystal is heated by a heating means,

the revolution base is configured to receive the rotation base and rotate the revolution base,

a chloride gas of a group III element is ejected from a first gas ejection port of a gas supply tool, a nitrogen-containing gas is ejected from a second gas ejection port, and an inert gas is ejected from a third gas ejection port, respectively, at a predetermined inclination with respect to an axial direction of a rotation shaft of the revolving base,

the gas is exhausted through an exhaust means.

7. The method of manufacturing a group III nitride substrate according to claim 6, wherein the third gas ejection port surrounds the first gas ejection port, and the second gas ejection port surrounds the third gas ejection port and is formed of a plurality of concentric pipes.

8. The method for manufacturing a group III nitride substrate according to claim 6 or 7, wherein the inclination is selected from a range of 5 ° or more and 85 ° or less.

9. The method for producing a group III nitride substrate according to any one of claims 6 to 8, wherein the inside of the reaction vessel is adjusted to a negative pressure that is lower than the atmospheric pressure by a pressure adjusting tool.

10. The method for producing a group III nitride substrate according to any one of claims 6 to 9, wherein the group III nitride is gallium nitride,

the seed crystal is a SCAM substrate or a gallium nitride substrate manufactured by a manufacturing method selected from the group consisting of MOCVD method, Na flux method, liquid ammonia method and hydride vapor phase growth method,

the chloride gas of the group III element is gallium trichloride or gallium chloride,

the nitrogen-containing gas is ammonia and is,

the inert gas is argon or nitrogen.

Technical Field

The present invention relates to an apparatus and a method for manufacturing a low-cost and high-quality group III nitride substrate such as AIN or GaN, and more particularly to an apparatus and a method for manufacturing a GaN crystal substrate.

Background

Crystalline AIN substrates or crystalline GaN substrates have a wide band gap, have a very short wavelength emission property or a high withstand voltage, and have excellent high-frequency characteristics, and are expected to be used for laser devices, power devices, or high-frequency devices. However, it is difficult to grow AIN or GaN crystals at present, and it is difficult to obtain a crystalline AIN substrate or a crystalline GaN substrate having high characteristics and low cost.

For example, in the case of GaN substrates, although a bulk GaN substrate obtained by growing GaN crystals in a liquid such as liquid ammonia (liquid ammonia process) or Na flux has high characteristics, it is still possible to produce a small diameter of 2 to 4 inches, and is extremely expensive and limited in use. In contrast, the Metal Organic Chemical Vapor Deposition (MOCVD) or hydride vapor deposition (HVPE, THVPE, etc.) which are crystal grown in a gas atmosphere, performs heteroepitaxial GaN growth on a sapphire substrate or an AIN substrate, thereby obtaining a GaN thin film having a relatively large diameter at a relatively low cost. However, a high-quality product cannot be obtained, and improvement thereof is desired. In particular, the hydride vapor phase epitaxy method (HVPE method, thwpe method) is expected to have high characteristics and high productivity because of the characteristics of the source gas, and thus carbon contamination is less, and the film formation rate is higher by one order of magnitude or more than that of the MOCVD method using an organic metal. However, since the gas ejection port or the interior of the reaction vessel is conventionally formedGaN as a product or NH as a by-product₄Cl and the like, so that the reaction can not be continued stably, and it is difficult to increase the size, at most, the reaction can be put into practical use on a small scale of laboratory scale not exceeding the range of a small quartz glass tube. Further, the obtained GaN crystal substrate has large variations in film quality, film thickness, and the like, and is poor in reproducibility and extremely poor in mass productivity. Therefore, it is desired to establish a novel method which can perform a uniform reaction and has no variation in quality, is large in size, and has mass productivity.

As a conventional hydride vapor phase growth method, for example, a method described in patent document 1 is known. In the method described in patent document 1, in the reaction of the HVPE method using GaCl as a Ga source, a double tube is used as a supply tube for a halogen gas (GaCl) and a seal gas (inert gas), the halogen gas is flowed through a central tube of the double tube, the seal gas is supplied from an outer tube, and ammonia gas is supplied from a gap between the double tube and a growth chamber (reaction tube), thereby obtaining a GaN crystal or the like. In the method described in patent document 1, a halogen gas is enclosed by a sealing gas using a double tube, thereby preventing premature reaction and accumulation of a reactant, and preventing a decrease in the crystal growth rate and clogging of a reaction system. However, this method is effective only in a very small device at a laboratory level, and is limited to a case where the gap between the double tube and the growth chamber (reaction tube) is very small. That is, in the method described in patent document 1, since ammonia gas is directly supplied from the gap between the double tube and the growth chamber (reaction tube) onto the crystal growth substrate, the flow path cross-sectional area of the ammonia flowing space, that is, the gap between the double tube and the growth chamber (reaction tube), becomes extremely large when the apparatus is increased in size in view of mass production. As a result, the flow rate of the ammonia gas becomes extremely low, and the ammonia gas in a sufficient amount required for the reaction does not reach the crystal growth substrate and a normal reaction or a heterogeneous reaction due to heterogeneous mixing is likely to occur, unlike the flow rate of the other gas supplied from the double pipe.

Patent document 2 also describes an invention related to the HVPE method, similar to patent document 1. The invention is designed particularly for the preparation of AIN series with a faster reaction speed than GaN. The object of the invention is to prevent the nozzle tip of the reaction gas outlet especiallyClogging of the end. That is, AlCl is applied to a substrate held in a reaction zone₃Isohaloaluminum gas and NH₃In a method for producing an aluminum nitride such as AlN by reacting an iso-nitrogen source gas, a barrier gas such as argon is interposed between a halogenated gas and the nitrogen source gas, two reaction gases are flowed out of a reaction region, and then the two reaction gases are brought into contact with each other on a substrate to carry out a reaction. More specifically, a double tube is provided in the chamber of the quartz reaction tube, so that for example AlCl is provided₃Passing an aluminum halide gas through the central tube to make NH₃While flowing the nitrogen source gas through a gap between the double tube and the chamber (quartz reaction tube) or through a different tube, for example, N is introduced₂Flows through the outer tube of the double tube and intervenes therein as a barrier gas between the aluminum halide gas and the nitrogen source gas, thereby preventing clogging of the tip of the double tube to which the reaction raw material gas is supplied. The invention described in patent document 2 is slightly different from the method described in patent document 1, and when the nitrogen source gas is caused to flow from the gap between the double tube and the chamber (quartz reaction tube) to the outside of the reaction gas ejection port for supplying the halogenated gas, it is feasible on a small-scale and small-scale for the same reason as described above, but is not suitable for a large-scale apparatus of a mass production level. In addition, in the reaction of NH₃When the nitrogen source gas flows through different tubes, the halogenated gas and the nitrogen source gas tend to form parallel flows, the reaction gas tends to be unevenly mixed, and it is difficult to obtain a uniform product.

The method described in patent document 3 is an HVPE method similar to the methods described in patent documents 1 and 2. However, the method described in patent document 3 is considered as follows: the nitrogen source gas is supplied from different supply pipes, and the barrier gas is also divided into two parts and the flow pattern and linear velocity are changed above and below the base substrate to prevent clogging and improve the reaction yield. However, this method has a drawback that it is difficult to uniformly supply the halogenated gas and the nitrogen source gas to the base substrate, and as a result, the two reaction gases are not uniformly mixed on the base substrate, and the film quality and the film thickness of the obtained GaN crystal are likely to be non-uniform. In any case, although patent documents 1 to 3 including this patent have some differences in purpose, the reaction system is basically of a small scale, and is not suitable for mass production.

On the other hand, patent document 4 describes the use of GaCl₃Although not specifically shown, the THVPE method as a Ga source is described in the description thereof, in fig. 10 and 11 of patent document 4, a gas outlet may be configured in a double-tube structure, and a gallium chloride gas is discharged from an inner tube and a barrier gas is discharged from an outer tube (reaction tube) in order to surround a gallium chloride gas flow coming out from the gas outlet with the barrier gas flow and prevent gallium chloride and NH before reaching a growth region₃And (4) reacting. However, this method is not suitable for mass production requiring a larger reaction, although it is sufficient if the scale is small, as in the above patent documents 1 to 3. That is, in the method described in patent document 4, since the reaction tube constituting the reaction chamber also serves as a part of the double tube, gallium chloride and NH are prevented from being contained in the barrier gas for the same reason as in patent documents 1 to 3 described above₃The reaction takes place before the zone is reached, and a sufficient gas flow rate is required, for which a large amount of barrier gas is required. As a result, the reaction gas is greatly diluted to an extremely low concentration state by a large amount of the barrier gas, resulting in a great decrease in the reaction rate. Conversely, if the barrier gas is reduced, then the gallium chloride and NH are added₃Interdiffusion occurs, barrier function is insufficient, and reaction products are in gallium chloride or NH₃The gas tube outlet(s) of (2) grow to cause clogging or unevenness or abnormal reaction, making it difficult to continue the reaction for a long time.

In any case, it has been shown in the methods described in the patent documents so far that the halogen gas (GaCl ) is prevented₃) And nitrogen source gas (NH)₃) For example, clogging of a reaction system such as a raw material gas pipe, an outlet of a reaction pipe (reaction chamber), a wall surface, or the like, and reduction in yield due to defects or unbalanced reaction of a reaction raw material gas, and a method of coating one of the reaction gases with a sealing gas, and using a double pipe and a barrier gas as a specific method have been proposed. However, the methods described in these patent documents still have the above-mentioned drawbacks, and a method for producing a group III nitride substrate having high characteristics is not yet established, which hinders mass production and mass reduction of the substrateThe cost is reduced.

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication No. 2002-542142

Patent document 2: japanese patent laid-open No. 2006 and 114845

Patent document 3: japanese patent laid-open No. 2014-69987

Patent document 4: international publication No. 2017/159311.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a manufacturing apparatus and a manufacturing method that can obtain a uniform and good group III nitride crystal substrate.

Means for solving the problems

In order to achieve the above object, the present invention provides the following apparatus and method for manufacturing a group III nitride substrate.

[1] An apparatus for manufacturing a group III nitride substrate, comprising: the reactor comprises a rotating susceptor for holding a seed crystal and rotating in a reaction vessel, a heating tool for heating the seed crystal, a revolving susceptor for accommodating the rotating susceptor and rotating, a first gas ejection port for ejecting a chloride gas of a group III element at a predetermined inclination with respect to an axial direction of a rotation axis of the revolving susceptor, a second gas ejection port for ejecting a nitrogen-containing gas, a third gas ejection port for ejecting an inert gas from between the first gas ejection port and the second gas ejection port, and an exhaust tool for exhausting a gas.

[2] The apparatus for producing a group III nitride substrate according to [1], wherein the third gas ejection port surrounds the first gas ejection port, and the second gas ejection port surrounds the third gas ejection port.

[3] The apparatus for producing a group III nitride substrate according to [1] or [2], wherein the inclination is selected from a range of 5 ° or more and 85 ° or less.

[4] The apparatus for manufacturing a group III nitride substrate according to any one of the above items [1] to [3], wherein an inner wall of the reaction vessel is coated with a material that does not react with the gases or reaction products of the gases ejected from the first gas ejection port, the second gas ejection port, and the third gas ejection port.

[5] The apparatus for manufacturing a group III nitride substrate according to any one of the above items [1] to [4], further comprising a pressure adjusting means for adjusting the inside of the reaction vessel to a negative pressure that is lower than the atmospheric pressure.

[6] A method for producing a group III nitride substrate, characterized in that a seed crystal is held on a rotation susceptor rotating in a reaction vessel, the seed crystal is heated by a heating tool, the rotation susceptor is placed on a revolution susceptor and housed therein, the revolution susceptor is rotated, a chloride gas of a group III element is ejected from a first gas ejection port of a gas supply tool, a nitrogen-containing gas is ejected from a second gas ejection port, an inert gas is ejected from a third gas ejection port, and the gases are exhausted by an exhaust tool, respectively, at a predetermined inclination with respect to the axial direction of the rotation axis of the revolution susceptor.

[7] The method for producing a group III nitride substrate according to [6], wherein the third port surrounds the first gas ejection port, and the second gas ejection port surrounds the third gas ejection port and is formed as a concentric multi-tube.

[8] The method for producing a group III nitride substrate according to any one of [6] and [7], wherein the inclination is selected from a range of 5 ° or more and 85 ° or less.

[9] The method for producing a group III nitride substrate according to any one of the above items [6] to [8], wherein the inside of the reaction vessel is adjusted to a negative pressure that is lower than the atmospheric pressure by a pressure adjusting tool.

[10] The method for producing a group III nitride substrate according to any one of the above items [6] to [9], wherein the group III nitride is gallium nitride, the seed crystal is an SCAM substrate or a gallium nitride substrate produced by a production method selected from the group consisting of an MOCVD method, a Na flux method, a liquid ammonia method and a hydride vapor phase growth method, the chloride gas of the group III element is gallium trichloride or gallium chloride, the nitrogen-containing gas is ammonia, and the inert gas is argon or nitrogen.

Effects of the invention

According to the present invention, a uniform and good group III nitride crystal substrate can be obtained.

Drawings

Fig. 1 is a schematic view of an apparatus for manufacturing a group III nitride substrate according to an embodiment of the present invention.

Fig. 2 is a schematic view of the apparatus for manufacturing a group III nitride substrate shown in fig. 1, as viewed from the direction of the rotation axis of the revolving susceptor.

FIG. 3 is a view showing a cross section of a first gas ejection port, a second gas ejection port and a third gas ejection port.

Fig. 4 is a diagram showing the arrangement of the spin base in embodiment 1.

Detailed Description

[ apparatus for producing group III nitride substrates ]

The following describes an apparatus for manufacturing a group III nitride substrate according to an embodiment of the present invention, but the apparatus for manufacturing a group III nitride substrate according to the present invention is not limited thereto.

Fig. 1 and 2 show an apparatus for manufacturing a group III nitride substrate according to an embodiment of the present invention. Fig. 1 is a schematic view of an apparatus for manufacturing a group III nitride substrate according to an embodiment of the present invention, and fig. 2 is a schematic view of the apparatus for manufacturing a group III nitride substrate shown in fig. 1, as viewed from a direction of a rotation axis of a revolving susceptor.

An apparatus for manufacturing a group III nitride substrate according to an embodiment of the present invention includes: a rotation susceptor 3 for holding and rotating the seed crystal 2 in the reaction vessel 1, a heating tool 9 for heating the seed crystal 2, a revolution susceptor 4 for accommodating and rotating the rotation susceptor 3, a first gas ejection port 6 for ejecting a chloride gas of a group III element at a predetermined inclination θ with respect to an axial direction of a rotation axis of the revolution susceptor 4, a second gas ejection port 7 for ejecting a nitrogen-containing gas, a third gas ejection port 8 for ejecting an inert gas from between the first gas ejection port 6 and the second gas ejection port 7, and an exhaust tool 5 for exhausting the gas are arranged. With the above configuration, the manufacturing apparatus for a group III nitride substrate according to one embodiment of the present invention can manufacture a large group III nitride substrate of high quality at low cost.

(seed crystal)

The seed crystal 2 is not particularly limited as long as it is a crystal that can grow a group III nitride film by a hydride vapor phase growth method (for example, HVPE method, THVPE method, or the like). As the group III nitride, AIN, GaN, and the like are exemplified. For example, when the group III nitride is GaN, it is preferable to use ScAlMgO₄A (SCAM) substrate or a GaN substrate manufactured by a method selected from MOCVD, Na flux, liquid ammonia, and hydride vapor phase growth is used as a seed substrate. The seed crystal is usually carried on the spin base 3 by a heat-resistant adhesive such as alumina or in an embedded manner. Then, at least GaCl is added₃And/or GaCl and N₂Isoinert gas and NH₃Supplied to the seed crystal, and a reaction for thickening the GaN crystal is carried out on the seed crystal.

Note that, if hydride vapor phase growth is performed without using a seed crystal, a GaN crystal cannot be obtained. In addition, when Si, SiC, AlN, GaAs, sapphire or the like is used as the seed crystal, the obtained GaN crystal may have many defects and poor characteristics or may have only a large warpage because of a significant difference in lattice constant or thermal expansion coefficient from the GaN crystal. Therefore, in the case where the group III nitride is GaN, the seed crystal 2 is preferably ScAlMgO, for example₄Like the (SCAM) substrate or the GaN substrate, the lattice constant or thermal expansion coefficient is substantially close to or equal to the crystal of the GaN substrate. By using such seed crystal 2, the obtained GaN crystal is free from warpage and few defects even when it has a large diameter, and a GaN crystal having high characteristics can be obtained.

(autorotation base)

The rotation susceptor 3 rotates while holding the seed crystal 2. The spin base 3 is made of heat-resistant ceramics such as PBN and corundum. The seed crystal 2 is held on the spin base 3 by using a heat-resistant adhesive such as alumina. The rotation speed of the spin base 3 is not particularly limited, but is preferably 10 to 40 rpm. When the rotation speed of the spin susceptor 3 is 10 to 40rpm, the uniformity of the obtained group III nitride crystal substrate becomes better and the rotation of the spin susceptor 3 can be stabilized more.

(heating tool)

The heating tool 9 heats the seed crystal 2. Thereby promoting the growth of the group III nitride on the seed crystal 2. The heating temperature of the seed crystal 2 is preferably 900-1400 ℃. When the heating temperature of the seed crystal 2 is 900 to 1400 ℃, the growth rate of the group III nitride crystal can be increased and the decomposition of the grown group III nitride crystal can be suppressed.

(revolution base)

The revolution base 4 rotates while being arranged to accommodate the rotation base 3. Heat-resistant ceramics such as PBN and corundum are also used for the revolving base 4. The revolution base 4 may be configured to accommodate one rotation base 3, or may be configured to accommodate two or more rotation bases 3. When the revolving base 4 rotates, the revolving base 3 revolves. By combining the rotation of the rotation susceptor 3 and the revolution of the rotation susceptor 3 by the rotation of the revolution susceptor 4, a uniform group III nitride film can be grown on the seed crystal 2. The rotation speed of the revolving base 4 is not particularly limited, but is preferably about half the rotation speed of the rotation base 3, and is preferably 5 to 20 rpm. If the revolution base 4 rotates at a speed about half that of the rotation base 3, the revolution base 4 can be rotated more stably. The revolving bed 4 may be rotated in the same direction as the rotating bed 3, or in a different direction. However, the revolving base 4 preferably rotates in the same direction as the rotating base 3.

(gas outlet)

As described above, the apparatus for manufacturing a group III nitride substrate according to one embodiment of the present invention includes the first gas ejection port 6, the second gas ejection port 7, and the third gas ejection port 8. The first gas ejection port 6 ejects a chloride gas of a group III element at a predetermined inclination θ with respect to the axial direction of the rotation axis of the revolving susceptor 4. As the chloride gas of the group III element, for example, AlCl is exemplified₃Gas, GaCl₃Gases, and the like. The second gas ejection port 7 ejects the nitrogen-containing gas at a predetermined inclination θ with respect to the axial direction of the rotation axis of the revolving susceptor 4. As the nitrogen-containing gas, for example, N is mentionedH₃Gases, and the like. Note that, N is₂The gas contains nitrogen, but is not a nitrogen-containing gas, and is included in the scope of the inert gas in the present specification. The third gas ejection port 8 ejects the inert gas from between the first gas ejection port 6 and the second gas ejection port 7 at a predetermined inclination θ with respect to the axial direction of the rotation axis of the revolving base 4. As the inert gas, for example, N is cited₂Gas, argon, and the like. Due to the inert gas, the chloride gas of the group III element ejected from the first gas ejection port 6 and the nitrogen-containing gas ejected from the second gas ejection port 7 can be prevented from reacting immediately after ejection. This prevents the first gas ejection ports 6 and the second gas ejection ports 7 from being blocked. From the viewpoint of more reliably preventing the chloride gas of the group III element ejected from the first gas ejection port 6 and the nitrogen-containing gas ejected from the second gas ejection port 7 from reacting immediately after ejection, as shown in fig. 3, it is preferable that the first gas ejection port 6 is surrounded by the third gas ejection port 8, and the second gas ejection port 7 is formed by a concentric multi-tube structure in which the third gas ejection port 8 is surrounded by the second gas ejection port 7. In particular, if the gas ejection ports are formed as a plurality of concentric pipes each composed of a dedicated pipe for each gas, the ejection angles of the respective gases can be made uniform, and a symmetrical reaction field can be formed. In addition, for adjustment of the size of the apparatus or the gas flow, a multiple tube (e.g., a quadruple tube to a sextuple tube) of three or more tubes may be used. For example, because of NH in the triple tube described above₃If the flow of (2) is too wide, the reaction product tends to deposit on the reaction vessel wall, so that in order to prevent this, N may be further used on the outer side₂Etc. inert gas flows through the quadruple pipe.

The first gas ejection port 6, the second gas ejection port 7, and the third gas ejection port 8 eject the respective gases at a predetermined inclination θ with respect to the axial direction of the rotation axis of the revolving susceptor 4, whereby a uniform group III nitride film can be grown on the seed crystal 2. From such a viewpoint, the predetermined inclination θ is preferably selected from a range of 5 ° or more and 85 ° or less. When the inclination θ is 5 ° or more, the reaction gas can be uniformly supplied to the surface of the rotation susceptor, and the thickness and properties of the group III nitride crystal to be produced can be made uniform. When the inclination θ is 85 ° or less, the group III nitride crystal can be prevented from being deposited and fixed on the shaft other than the surface of the rotation susceptor 3, the revolution susceptor 4, or the like, and not being reacted on the surface, and the occurrence of rotation failure such as rotation and revolution can be prevented. The inclination θ may be selected appropriately from the range in consideration of the number and arrangement of the rotation susceptors 3 on the revolution susceptor 4, the linear velocity of the supplied gas, the rotation speed and revolution speed of the rotation and revolution, the exhaust speed, and the like. From the above viewpoint, the predetermined inclination θ is more preferably 10 ° or more and 60 ° or less, and still more preferably 20 ° or more and 45 ° or less.

The gas ejection at the predetermined inclination θ is combined with the rotation and revolution of the rotating susceptor 3, and the gas can be very uniformly dispersed and mixed on the respective rotating susceptors 3 by their synergistic effect. As a result, when a plurality of spin susceptors 3 are arranged, a uniform crystal growth reaction can be performed on any spin susceptor 3 with high yield. In addition, the trouble of other apparatus parts which have been troubled by the accumulation or clogging of the reaction product in the past is solved in addition to the gas ejection port, and the reaction can be continued for a long time to obtain a group III nitride crystal having excellent characteristics.

In the hydride vapor phase growth, since the target group III nitride substrate is used as a semiconductor substrate, various metal impurities must be avoided as much as possible. For hydride vapor phase growth, since GaCl and/or GaCl are typical₃And NH, which is hygroscopic and is produced in large amounts as a by-product of the reaction, since ammonia is used as a reaction raw material₄Cl is easily attached to the inner wall of the reaction vessel, etc. The attached NH₄When the reaction vessel is opened or closed, chlorine ions are generated due to moisture in the air, and when the reaction vessel is made of metal, metal corrosion occurs, and metal contamination of the group III nitride crystal is likely to occur. Therefore, the inner wall of the reaction container 1 is preferably coated with a material that does not react with the gases ejected from the first gas ejection port 6, the second gas ejection port 7, and the third gas ejection port 8 or the reaction products of these gases. Specifically, it is preferable to preliminarily prepare the inner wall or member of the apparatus involved in the reactionEtc. are coated with a material that is not substantially reactive with the reactive gas and then reacted, such as quartz glass or zirconia ceramics and/or high melting point metals such as Mo, W, etc., thermal spraying is suitable for coating. The group III nitride substrate thus obtained is free from metal contamination and exhibits high characteristics in the production of a device. In the vapor phase growth reaction, it is preferable that the inner wall from the reaction vessel to the exhaust means is kept at a temperature of 500 ℃ or higher by using the heating means 9, for example, to reduce the adhesion of the reaction by-products. In addition, from the viewpoint of keeping the inner wall of the reaction vessel 1 warm, the outside of the heating tool 9 is preferably covered with the heat insulating material 10.

(exhaust tool)

The gas exhausting means 5 exhausts the gas in the reaction vessel. This makes it possible to discharge unnecessary gas from the reaction vessel and to maintain the pressure in the reaction vessel constant.

(pressure adjusting means)

The apparatus for producing a group III nitride substrate according to one embodiment of the present invention preferably includes a pressure adjustment means for adjusting the interior of the reaction vessel 1 to a negative pressure that is lower than the atmospheric pressure. The pressure in the reaction vessel 1 is preferably 200 to 600 Torr. When the pressure in the reaction vessel 1 is 200 to 600 torr, a group III nitride substrate having a more favorable film thickness distribution and no characteristic variation can be obtained. Conventional hydride vapor phase growth is generally carried out under a positive pressure slightly higher than atmospheric pressure in order to increase the reaction rate as much as possible, but has a disadvantage of poor film thickness uniformity. The apparatus for manufacturing a group III nitride substrate according to one embodiment of the present invention supplies a gas at a constant inclination with respect to the axial direction of the rotation axis of the revolving susceptor, and simultaneously, in conjunction with planetary motion by rotation and revolution of the rotation susceptor and the revolving susceptor, the reaction gas is mixed very uniformly on the rotation susceptor, and as a result, the reaction efficiency is high and the reaction speed is also very high. Although the obtained group III nitride crystal can be substantially satisfactory in terms of film thickness, variation in characteristics, and the like, it is preferable to maintain the reaction vessel at a slightly negative pressure compared with the atmospheric pressure in order to further reduce flatness and variation, thereby obtaining a group III nitride substrate having a more favorable film thickness distribution or no variation in characteristics.

[ method for producing group III nitride substrate ]

The method for producing a group III nitride substrate of the present invention is characterized in that a seed crystal is held on a rotation susceptor rotating in a reaction vessel, the seed crystal is heated by a heating tool, the rotation susceptor is placed and housed on a revolution susceptor, the revolution susceptor is rotated, a chloride gas of a group III element is ejected from a first gas ejection port of a gas supply tool, a nitrogen-containing gas is ejected from a second gas ejection port, and an inert gas is ejected from a third gas ejection port at a predetermined inclination with respect to the axial direction of the rotation axis of the revolution susceptor, and the gases are exhausted by an exhaust tool. The method for manufacturing a group III nitride substrate according to the present invention has the above-described structure, and thus a large group III nitride substrate with high quality can be manufactured at low cost.

The method for manufacturing a group III nitride substrate of the present invention can be carried out using, for example, the apparatus for manufacturing a group III nitride substrate according to one embodiment of the present invention. Specifically, the seed crystal 2 is held on the rotation susceptor 3 rotating in the reaction vessel 1, the seed crystal 2 is heated by the heating tool 9, the rotation susceptor 3 is placed on the revolution susceptor 4, the revolution susceptor 4 is rotated, the chloride gas of the group III element is discharged from the first gas discharge port 6 of the gas supply tool, the nitrogen-containing gas is discharged from the second gas discharge port 7, and the inert gas is discharged from the third gas discharge port 8 at a predetermined inclination θ with respect to the axial direction of the rotation axis of the revolution susceptor 4, respectively, and the gases are discharged by the gas discharge tool 5.

In the method for producing a group III nitride substrate of the present invention, the third gas ejection port preferably surrounds the first gas ejection port, and the second gas ejection port preferably surrounds the third gas ejection port.

In the method for producing a group III nitride substrate according to the present invention, the inclination is preferably selected from the range of 5 ° or more and 85 ° or less, as in the apparatus for producing a group III nitride substrate according to one embodiment of the present invention.

In the method for producing a group III nitride substrate of the present invention, as in the apparatus for producing a group III nitride substrate according to one embodiment of the present invention, it is also preferable that the inside of the reaction vessel is adjusted to a negative pressure that is lower than the atmospheric pressure by a pressure adjustment tool.

In the method for producing a group III nitride substrate of the present invention, the group III nitride is preferably gallium nitride, the seed crystal is preferably a SCAM substrate or a gallium nitride substrate produced by a production method selected from the group consisting of MOCVD, Na flux, liquid ammonia, and hydride vapor phase growth, the chloride gas of the group III element is preferably gallium trichloride or gallium chloride, the nitrogen-containing gas is preferably ammonia, and the inert gas is preferably argon or nitrogen.

Examples

Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

[ example 1]

A stainless steel reaction vessel 1 (inner surface coated with extra thin thermal sprayed zirconia) having an inner diameter of 1500mm × a height of 1800mm shown in FIG. 1 of the schematic drawing, which is provided with a water-cooled jacket (not shown), an exhaust port 5, and a vacuum pump (not shown) downstream of the exhaust port, and which is provided with a cylindrical and rod-shaped heater 9 (inner diameter of 1000mm × height of 1300mm) of a SiC heater and a PBN (thermally decomposed boron nitride) gas ejection port of a concentric triple tube (structure in which the inner diameter of a central tube is 30mm, the inner diameter of a second tube is 40mm, the inner diameter of the outermost tube is 50mm, and the inclination θ of the gas ejection port can be changed) is surrounded by a felt-like heat insulating material 10 of alumina. On the other hand, a revolution base 4 of PBN-coated graphite having a diameter of 520mm was prepared, and three PBN-made rotation bases 3 having a diameter of 170mm were placed on the revolution base 4 at intervals of 120 degrees as shown in FIG. 4. On the surface of this turning susceptor, a seed substrate 2 of 2-inch GaN prepared by a liquid ammonia process was processed into a tile-like seed substrate, which was bonded to a 6-inch disk shape with an alumina-based bonding material, and then heated to 1050 ℃. At the same time, the revolution base 4 revolves at 10rpm, using a revolution gearAfter the three rotation susceptors 3 were rotated at 30rpm by force and the temperature and rotation were confirmed to be stable, a vacuum pump connected to an exhaust port 5 was operated to supply GaCl from a center tube 6 (first gas discharge port) of a triple tube so as to maintain the inside of the reaction vessel at 500 torr₃Gas, NH supplied from the outermost pipe 7 (second gas ejection port)₃Gas is supplied from a pipe 8 (third gas outlet) between the center pipe and the outermost pipe to supply N₂The THVPE reaction was carried out for 95 hours while keeping the gas in order to prevent clogging, and the in-plane thickness of the GaN crystal was substantially uniform, thereby obtaining a crystal of about 30 mm. During this period, the gas outlets, the susceptor, and the like are not filled with GaN or NH as a by-product₄A gas ejection port clogging due to Cl or the like, and a trouble due to sedimentation around the susceptor. The gas ejection port in the thwpe reaction was adjusted by a variable device so as to have a constant inclination of 30 ° with respect to the axial direction of the rotation axis (revolution axis) of the revolution base. The obtained GaN crystal was processed into 6 inches in diameter by barrel grinding, and then appropriately sliced and polished to prepare a substrate 625 μm thick. For FWHM (full width at half maximum) of the X-ray rocking curve of the (100) plane of this substrate, any three points in the plane were 31 arcsec on average and 4 arcsec in deviation. In addition, as a result of observing stacking faults with a monochromatic cathodoluminescence image, almost no stacking faults were observed in the surface layer of GaN. As is apparent from the above measurement and observation, the obtained GaN crystal was a uniform and good crystal substrate with very little variation.

Comparative example 1

The reaction was carried out under exactly the same conditions except that the rotation (revolution) of the revolving susceptor was stopped in the reaction vessel of example 1, and the rotation configuration was changed so that each of the three susceptors could be directly rotated at 30 rpm. As a result, the in-plane thickness of the 6-inch GaN crystal obtained after the THVPE reaction was 5 to 18mm, and the variation was large, and the GaN yield was extremely poor. This was sliced and ground to prepare a substrate having a thickness of 625 μm, and the FWHM was measured and was 430 arc seconds on average and 120 arc seconds off-set, indicating non-uniform crystallization in the plane. In addition, many stacking faults were observed on the surface of the GaN substrate in the observation of monochromatic cathodoluminescence images. As is clear from example 1 and comparative example 1, the effect of combining the revolution of the susceptor holding jig and the rotation of each susceptor is remarkable, and the reaction gases are uniformly mixed on the susceptors due to the synergistic effect of these, and as a result, the obtained GaN crystal substrate is obtained with good yield and is uniform and good crystal without variation.

[ example 2]

GaCl was added using the reaction vessel of example 1₃The gas was changed to GaCl so that the linear velocity of the GaCl gas fed from the center tube of the triple tube was the same as that of GaCl in example 1₃The reaction by the so-called HVPE method was performed in the same manner as in the gas linear velocity of (1), by adjusting the wall thickness of the center tube to be increased. Other conditions were substantially the same as in example 1. The reaction was the same as in example 1, and clogging of the gas ejection port or production of GaN or NH did not occur₄Cl deposition around the susceptor, and the like. The in-plane thickness of the obtained GaN crystal was approximately uniform and was about 12 mm. The obtained GaN crystal was fabricated into a 5 μm substrate in the same manner as in example 1. For the FWHM of the X-ray rocking curve of the (100) plane of the substrate, any three points in the plane averaged 52 arcsec with a deviation of 5 arcsec. In addition, as a result of observing stacking faults with a monochromatic cathodoluminescence image, almost no stacking faults were observed in the surface layer of GaN. As is apparent from the above measurement and observation, the obtained GaN crystal was a uniform and good crystal substrate with very little variation.

[ example 3]

The apparatus of example 1 was rotated by 90 ° and the susceptor was arranged vertically upward. The reaction was carried out in exactly the same manner as in example 1 except that the relative positional relationship among the gas ejection port, the rotation susceptor, the revolution susceptor, the exhaust port, and the like was not changed by adjusting the variable device so that the gas ejection port was inclined downward at a constant inclination of 15 ° with respect to the axial direction of the rotation shaft of the revolution susceptor. As a result, the in-plane thickness of the obtained GaN was substantially uniform, and a crystal of about 35mm was obtained. During the reaction, GaN or NH as a by-product does not occur around the gas ejection port or the susceptor₄A blockage of the gas ejection port due to Cl or the like, and a deposition around the susceptor. The obtained GaN crystal was evaluated in the same manner as in example 1, and the evaluation was made for the GaN crystalThe FWHM of the X-ray rocking curve of the (100) plane of the substrate was 48 arcsec on average at any three points in the plane with a deviation of 7 arcsec. In addition, as a result of observing stacking faults with a monochromatic cathodoluminescence image, almost no stacking faults were observed in the surface layer of GaN. As is apparent from the above measurement and observation, the obtained GaN crystal was a uniform and good crystal substrate with very little variation.

[ example 4]

The reaction was carried out under exactly the same conditions as in example 1, except that the vacuum pump was not operated but was carried out under atmospheric pressure. As a result, the obtained GaN crystal has an in-plane thickness of 20 to 35mm and a large variation. Further, the same measurement and evaluation as in example 1 were carried out, and the FWHM was measured and found to be 185 arcsec on average, and the variation was 20 arcsec, slightly larger, but showed uniform crystals in the plane. In addition, in the observation of the monochromatic cathodoluminescence image, almost no stacking fault was observed on the surface of the GaN substrate.

Description of the marks

1 reaction vessel

2 seed crystal

3 self-rotating base

4 revolution base

5 exhaust port

6 first gas ejection port

7 second gas outlet

8 third gas outlet

9 heating tool

10 insulating material.