JPH08151299A - Methods for synthesizing compound semiconductor and growing single crystal and apparatuses for synthesizing compound semiconductor and growing single crystal - Google Patents

Abstract

PURPOSE: To provide apparatuses for carrying out the synthesis and growth of a single crystal of a III-V compound semiconductor in a stable thermal environment with a slight fluctuation in the height of a liquid surface of a raw material melt in a crucible. CONSTITUTION: A nonvolatile component raw material is placed in a crucible 2 and converted into a raw material melt 3. The lower bottom 41 of a top and bottom bisected type hermetically sealed container 4 having the opened bottom is inserted into the crucible 2 to thereby bisect the raw material melt 3 into the inside and outside. The raw material melt in an outside region is covered with a liquid encapsulating agent 5. The melt can be made to flow through a gap 42 or a communication hole at the lower end 41 of the hermetically sealed container 4 to the inside and outside. A reservoir part 8 for a volatile component is provided in the upper part of the hermetically sealed container 4. The vapor of the volatile component is introduced from the reservoir part 8 on the upper side into the hermetically sealed container 4. A connecting part of the upper to the lower containers is sealed with a liquid encapsulating agent 48. The volatile component gas fed from the upper side is combined with the nonvolatile component melt in the crucible to afford a melt of a group III-V compound, which is then grown into a single crystal according to a pulling up method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for synthesizing a compound semiconductor such as GaAs and InP, a method for growing a single crystal, a synthesizing apparatus,
The present invention relates to a single crystal growth apparatus.

[0002]

2. Description of the Related Art Group 3 raw materials (nonvolatile components, Ga, In)
Compounding the group 5 raw materials (volatile components As, P, Sb) with each other to produce a compound is referred to as the synthesis of the group 3-5 compound.
Pulling a single crystal of a Group 3-5 compound is called growing or growing a single crystal. The present invention relates to the synthesis of Group 3-5 materials and the growth of Group 3-5 single crystals. The synthesis is not explained because the definition is clear. A little about single crystal growth. There are roughly two methods for obtaining a single crystal of a Group 3-5 semiconductor. Here, the indirect synthesis method and the direct synthesis method are assumed.

Indirect synthesis is a process in which raw material synthesis and single crystal growth are separated. The Group 3 raw material and the Group 5 raw material are heated and reacted in advance to synthesize a compound of the Group 3-5. The raw material solid of this compound is put into a crucible in a crystal growth apparatus, sealed with a liquid sealant, heated to form a melt, and a seed crystal is attached to the upper shaft and immersed in the melt to form a single crystal. Pull up. Synthesis and crystal growth are different processes. That is why it is called indirect synthesis. On the other hand, the combination of the Group 3 raw material and the Group 5 raw material and the crystal pulling by the same apparatus is called direct synthesis. This is because the raw materials are directly synthesized by the crystal pulling device.

The present invention is directed to the synthesis of materials in indirect synthesis and the growth of single crystals by direct synthesis. The purpose is different, but the place of creativity is the same. Some of the prior art regarding these methods will be described. G for simplicity
Although aAs is often mentioned, the same applies to other 3-5 groups.

[Conventional Example (High Pressure Synthesis Method)] The most common method for synthesizing a Group 3-5 compound semiconductor material is a high pressure synthesis method. Put As, Ga and B ₂ O ₃ solids in the crucible,
Ga + As in the crucible is heated as a melt by applying high pressure.
→ This is a method of causing a reaction called GaAs. That is, volatile components (As, P), non-volatile components (Ga, I)
n), the liquid sealant (B ₂ O ₃ ) is put together in a crucible and heated to melt and react. The liquid sealant covers the melt surface. Due to the high pressure, the liquid sealant prevents the Group 5 escape. However, this has a drawback that a high pressure must be applied and the loss of As is large.

[Conventional Example (Group 5 injection synthesis method)] A volatile component vapor is continuously supplied to the non-volatile component melt in the crucible separately from the volatile component and the non-volatile component. A group 5 injection method for synthesizing Put the tribe into the crucible and melt it. A group 5 reservoir is provided above the crucible, and a supply pipe is hung from this reservoir and inserted into the melt of the crucible. Since Group 5 vapor enters the Group 3 melt, a Group 3-5 compound is produced. This is because the supply pipe of the 5th group (As, P) is 3
Since it is inserted into the group melt (Ga, In), a 3-5 group compound is formed at the lower end, which may clog the supply pipe. Since Group 5 is supplied through a thin supply pipe, there is a drawback that the chemical reaction is slow and the synthesis efficiency is poor.

[Conventional Example (Double Columnar Tube Synthesis Method)] This is proposed in, for example, JP-A-61-174105.
FIG. 4 shows an outline of this device. This does not show an external pressure vessel. In reality, these are all surrounded by a pressure chamber. A crucible 71 supported by the lower shaft 70 contains a melt 24 of a non-volatile raw material of a Group 3 element (Ga, In, etc.). The heater 72 is heating the melt. Into the Group 3 melt 24, the open ends of the double columnar tubes 23, which are inner and outer double tubes, are inserted. The open end divides the non-volatile component (Group 3) melt into two parts.
The upper surface of the melt in the outer region Z is the liquid sealant 25 (B ₂ O ₃ ).
Covered by. The melt in the inner region M is exposed in the internal space S. This is because the volatile component must be dissolved in the melt from the interface and reacted with the non-volatile component melt.

The inner / outer double tube 23 is a combination of an inner tube 74 and an outer tube 75 of PBN. The volatile component (group 5 raw material) solid 22 is put into an outer tube having a hemispherical top, and an inner tube 74 having a flat top is inserted to fix both. A volatile component reservoir 73 is formed between the inner and outer tubes at the top.
The outer diameter of the inner pipe and the inner diameter of the outer pipe are similar, and the gap is narrow. There is a communication hole 26 in the middle of the inner pipe. Combined double columnar tube 2
Turn 3 upside down and stand in crucible 71. Then, the volatile component solid 22 is placed on the shelf at the top of the inner tube. The heater 72 heats the Group 3 (nonvolatile component) raw material in the crucible to make it a melt. The volatile component reservoir 73 is heated,
The Group 5 raw material sublimes, becomes gas, and descends. This passes through the inner and outer gaps and enters the internal space S from the communication hole 26. Since it contacts the Group 3 melt here, a chemical reaction occurs,
A melt of the Group 5 compound is formed.

Liquid sealant 25 outside the double columnar tube 23
Is for preventing the group 5 (volatile) element from coming out of the molten liquid of the group 3-5. Since the Group 5 element is extremely easy to dissociate, the liquid sealant prevents the dissociation. The liquid sealant also plays the role of preventing the entry of impurities from the outside. The melt in the crucible gradually replaces the melt of Group 5 with the melt of Group 3-5. Because of the communication hole 26, the As pressure in the volatile component reservoir 73 and the As pressure in the internal space S become equal. When all the Group 3 raw material melts replace the Group 3-5 melts, the synthesis work ends.
The solidified Group 3-5 compound semiconductor polycrystal is taken out from the crucible after cooling.

[Conventional Example (LEC Method: Indirect Synthesis Method)] 3
A conventional technique will be described with respect to the group-5 single crystal pulling method.
The most typical one is LEC method (liquid capsule method, liquid sealed Czochralski method). This is a method of pulling a single crystal by lowering and seeding a seed crystal in a Group 3-5 raw material melt covered with a liquid sealant and gradually pulling the seed crystal while rotating. This is an indirect synthetic method starting from Group 3-5 raw materials.

[Conventional example (high pressure direct synthesis pulling method)]
This is a pulling method corresponding to the conventional example. Place the Group 3 solids, Group 5 solids, and liquid sealant together in the crucible. A seed crystal is attached to the upper axis. The raw material in the crucible is heated all at once by a heater to form a melt. The liquid sealant covers the liquid surface. High pressure is applied to prevent the dissociation and escape of group 5. In the crucible, 3-5
Group compounds are synthesized. When this is over, the seed crystal is lowered. The melt is contacted, seeded and pulled up. Following the seed crystal, the single crystal pulls up. This is also a large-scale device because it requires high pressure. Further, there is a drawback that the loss of Group 5 vapor is large.

[Conventional Example (Group 5 Direct Injection Synthetic Pulling Method)] This is a crystal pulling method corresponding to the conventional example. Group 3 raw materials (Ga, In) and liquid sealant (B ₂ O ₃ ) in crucible
Place a Group 5 reservoir above the crucible and connect it to the crucible via a thin supply pipe. A seed crystal is attached to the lower end of the upper shaft. When the Group 3 raw material and the liquid sealant are heated by the heater, the melt of the Group 3 is covered with the liquid sealant in the crucible. The Group 5 reservoir is also heated to inject Group 5 vapor into the Group 3 melt. Group 3-5 compounds are synthesized in the crucible. Thereafter, the seed crystal is brought into contact with the Group 3-5 melt and seeded to pull up the single crystal. This is likely to cause clogging of thin supply pipes during the synthesis stage. Also, high pressure is required to hold down the liquid sealant. It has the drawback of low synthesis efficiency.

[Conventional Example (Internal and External Double Crucible Single Crystal Pulling Method)] This is a method in which the crucible is divided into the inner and outer parts and the crystal is pulled from the inner portion. This is a method that can utilize both indirect synthetic growth and direct synthetic growth. The structure of the crucible will be described with reference to FIG. This is disclosed, for example, in JP-A-60-176.
No. 995. Direct synthesis single crystal growth method also has 3
It can also be used in a single crystal growth method from a Group-5 raw material.
The outer wall of the furnace and the heater are not shown. The temperature of the Group 5 solid is controlled in the low temperature portion of the furnace, and the vapor pressure of the Group 5 is controlled. Since the pressure of group 5 is controlled, it is not necessary to apply the high pressure of the inert gas. It is a vapor pressure control raising method.

The crucible 76 is divided into the inside and outside by a cylinder 77. The surface of the Group 3-5 melt 78 is also divided into two. The inner surface 79 of the melt 78 exposes the melt. Only the outer surface 80 is covered with the liquid sealant 27. The seed crystal is hung down on the inside of the melt, and the 3-5 group single crystal is pulled up from here. The liquid sealant 27 covering the outer surface 80 is for preventing impurities from entering. This is 2
It has a heavy meaning. One is to prevent impurities from falling from the external space and entering the melt. The other is to absorb and remove impurities and the like contained in the melt by the liquid sealant. The liquid sealant has a function of gettering impurities. This is being used effectively.

[Conventional Example (Continuous Charge Lifting Method)]
Put the Group 3 raw material in the crucible and combine with the Group 5 raw material,
The method of pulling the crystal from here as a Group 5 melt is
The size of the crystal is limited by the amount of the Group 3 raw material initially filled in the crucible. In order to make a large and long crystal, the crucible must be enlarged. However, the crucible itself is expensive. This is because it is made of an expensive material such as PBN.
If the crucible is large, the heater and the shaft are also large, and the amount of the liquid sealant is large. In addition, the overall size of the furnace must be increased. Therefore, an improvement was made in which the Group 3 raw material was stored in a different place in the furnace and the Group 3 raw material was added to the crucible from here as needed.

This is called a continuous charge raising method. This is because the raw material is fed into the crucible from the reservoir of the raw material of Group 3 and Group 5 by a thin supply pipe, so that there is a problem of clogging of the supply pipe. There are various proposals, but here, JP-A-4-154 is used.
No. 689 will be described. This is shown in FIG.

There is a large closed container 29 which covers the whole. Of course, there is a large furnace body outside the closed container 29. This is not shown. The closed container 29 is formed by combining a bottomed cylindrical lower container 81 and a heavenly cylindrical upper container 82 at an intermediate joint portion 101. Closed container 2
A lower shaft 83 is vertically provided inside the unit 9. The bottomed cylindrical crucible 28 is placed on the susceptor 84 above the lower shaft 83. In the crucible 28, the raw material melt 8 of the group 3-5
5 are accommodated. There is a floating crucible 86 near the center of the upper portion of the melt 85. It has a conical cross section and floats in the melt 85 by buoyancy. A communication hole 87 is opened at the center so that the melt can flow from the inside to the outside.

The portion where the lower shaft 83 penetrates the closed container 29 is sealed with a liquid sealant. Vertical shaft 88 with lower shaft 83
Penetrate therethrough, and a liquid sealant reservoir 89 is placed on this, and the liquid sealant is contained therein. It is possible to rotate the shaft while preventing the gas inside and outside from mixing.
A main heater 90 is provided on the outer peripheral portion of the crucible 28. This is a resistance heating heater made of carbon. There is an auxiliary heater 91 on the side of the penetrating portion of the lower shaft 83. This is to heat the liquid sealant and maintain it in a liquid state. A liquid sealant heater 92 is provided on the side of the connecting portion 101 of the closed container 29.
Is provided.

Above the closed container 29, a group 5 raw material reservoir 30 and a group 3 raw material reservoir 31 are installed. Solids of volatile components such as As and P are stored in the group 5 raw material reservoir 30. The Group 3 raw material reservoir 31 stores solid raw materials such as Ga and In. The Group 3 raw material is heated by the Group 3 heater 93 to become a melt. The Group 5 raw material is heated by the Group 5 heater 94 and sublimates into a vapor state.

An upper shaft 95 penetrates the upper wall of the closed container 29. A seed crystal 96 is previously fixed to the lower end of the upper shaft 95. Following the seed crystal 96, the single crystal 97 is pulled out of the melt 85. The penetrating portion 98 of the upper shaft is also sealed by the liquid sealant. A dish-shaped container 99 is provided on the top of the upper container 82.
And the liquid sealant 100 is contained therein. The liquid sealant 100 allows the upper shaft to rotate and prevents gas from flowing in and out. A rotary seal made of a liquid sealant is used for both the upper shaft and the lower shaft.

The lower container 81 and the upper container 82 are connected at the joining portion 101 of the closed container 29. An annular groove 105 including an outer wall 102, a bottom wall 103, and an inner wall 104 is formed at the upper end of the circumference of the lower container. The upper end of the annular groove 105 is open, and the liquid sealant 106 is contained therein. The lower end 107 of the upper container 82 is inserted into the liquid sealant 106 in the annular groove 105. Liquid sealant 10
6 prevents the gas in the external space W from entering the internal space S. Impurities do not enter inside, so the melt inside is not contaminated. On the contrary, it also prevents the internal gas (As, P) from escaping to the outside. However, when the pressure in the internal space becomes too large, the gas escapes through the liquid sealant, so that the pressure difference between the inside and the outside is kept within a certain range.

In the upper group 3 reservoir 31, there is a melt 108 of the group 3 raw material. A supply pipe 33 having a curved portion 109 at the upper side stores the reservoir portion 31 in the crucible 28 inside the closed container 29.
Connected to. The supply pipe 33 is a thin pipe, and the reservoir 3
It penetrates the upper wall of the closed container from 1, and descends further, and is immersed in the melt 85 in the crucible 28. The lower end 110 of the supply pipe 33 opens into the melt 85.

In the group 5 reservoir 30, vapors of As or P and solids coexist. From the outlet 111, the group 5 vapor flows down the supply pipe 32 and is blown into the melt from the lower end 112. It is important that the Group 5 supply pipe 32 is open inside the melt. If this is not the case, the Group 5 vapor does not come into sufficient contact and is difficult to react with the Group 3 melt. Airtight container 29
At the bottom of the group 5, there is a Group 5 solid 113, and the Group 5 vapor pressure in the closed container can be controlled by adjusting the temperature of the solid. The temperature can be controlled by the heater 91. This apparatus pulls a single crystal out of a crucible and stores new raw material in a portion 30 corresponding to the decrease in raw material.
Since additional supply can be made from 31, a long crystal can be pulled up.

[0024]

The methods for producing a compound semiconductor single crystal described above have their respective advantages. However, these still have drawbacks. Conventional example ...
As for, the drawbacks have already been explained. Describe the difficulties with ,.

[Problems of Conventional Example] Japanese Unexamined Patent Application Publication No. 6-63 shown in FIG.
The synthesis technique of No. 1-174105 has the following problems. A pressure difference may occur between the inside S and the outside W of the closed container (double columnar tube 23). There is no means to eliminate the pressure difference. When there is a pressure difference, the melt surface fluctuates significantly up and down. If the liquid level changes, the height with respect to the heater changes,
The temperature distribution in the melt changes. Therefore, it was difficult to synthesize a single crystal in a stable thermal environment. When the pressure difference further increases, the melt may be sucked into the double columnar tube 23 or may be discharged to the outside. This is because the inside and the outside of the hermetically sealed container are completely cut off at a portion other than the melt, and the pressure difference directly causes a difference in the height of the melt.

In order to suppress such a phenomenon, the temperature of the ampoule filled with the volatile component raw material and the pressure inside the furnace must be strictly controlled so that no pressure difference occurs between the inside and the outside. But this is difficult. There are further procedural problems. The double columnar tube is actually fixed to the upper shaft so that it can move up and down. After the non-volatile component raw material (group 3) and the liquid sealant (B ₂ O ₃ ) thereon are melted, the double columnar tube 23 is lowered and its opening is inserted into the melt 24. A part of the liquid sealant remains in the inner region. The residual liquid sealant sometimes obstructs the reaction between the volatile gas entering the internal space S and the non-volatile component melt M.

[Problems of Conventional Example] The vapor pressure control raising technique (Japanese Patent Laid-Open No. 176995/1985) shown in FIG. 5 has the following drawbacks. A large crucible partitioned inside and outside is housed inside a sealed container. The temperature of the Group 5 solid is controlled in a closed container to control the vapor pressure of Group 5 inside the container. It is necessary to store the entire crucible that can be separated into the inside and the outside in a closed container. The sealed container becomes large. The furnace body surrounding all of them also needs to be larger. For this reason, the device becomes large in size and has a complicated structure. In principle, there should be no need for a liquid sealant over the melt as it controls the vapor pressure. However, in practice, it is not possible to prevent contamination of the raw material melt from the upper space, so it was necessary to divide the crucible into two parts, inside and outside, and cover one melt with the liquid sealant.

[Problems of Conventional Example] The one shown in FIG. 6 (Japanese Patent Laid-Open No. 4-154689) has a volatile component raw material,
A non-volatile component raw material is continuously supplied to the crucible. While supplying the raw materials, a Group 3-5 single crystal is grown. Nonvolatile component raw materials (Ga, In) are supplied through a thin supply pipe 33 inside the closed container 29 in an atmosphere of volatile components (As, P). At the tip of the Group 3 supply pipe 33, the Group 3 and Group 5 raw materials are reacted and solidified, and the supply pipe 33
Sometimes clogged.

Furthermore, volatile component gases (As, P)
The tip of the supply pipe 32 is inserted into the melt 85. When the internal pressure of the volatile component raw material reservoir 30 decreases, the supply pipe 3
2 sucks up the melt 85. Supply pipes for Group 5 and Group 3 materials
In some cases, the reaction may occur in the inside of 2 and solidify to clog the supply pipe 32.

Closed container 2 with vapor of Group 5 solid 113
Since it is necessary to control the group 5 partial pressure inside 9, the raw material melt 8
5 cannot be covered by the liquid sealant. Since there is no protective film of the liquid sealant, the raw material melt 85 may be contaminated by impurities present in the space S. A method for solving the above-mentioned problems and for synthesizing a compound semiconductor and growing a single crystal in a more stable environment without being contaminated by impurities by a simpler device is provided. That is the object of the present invention.

[0031]

According to the method for synthesizing a compound semiconductor of the present invention, the lower end of a closed container having a reservoir for volatile component raw material at the upper portion and having an opening at the lower portion is inserted into a crucible, and is partially connected. Divide the crucible into an inner side and an outer side so that the non-volatile component raw material and the liquid sealant are put in the crucible, the non-volatile component raw material and the liquid sealant are melted to form a melt, and the non-volatile component raw material is stored in the outer region. It is covered with a liquid sealant so that the non-volatile components are exposed in the inner region, and the volatile component raw material is heated and introduced as vapor into the internal space of the closed container to contact the non-volatile component melt in the inner region of the crucible. The volatile component raw material and the non-volatile component raw material are combined to synthesize a compound melt.

The compound semiconductor synthesizing apparatus of the present invention comprises a crucible for holding the non-volatile component melt, a lower shaft for holding the crucible, a heater for heating the raw material inside the crucible,
A closed container in which an upper container and a lower container are combined to divide the raw material melt into an inner region and an outer region so that the inner region is hermetically closed so as to communicate only with the bottom of the crucible, and an upper container and a lower container. A heater for heating the coupling part of the container, a reservoir provided on the closed container for containing volatile components, a heater for the volatile component reservoir, and an annular groove formed on the upper end of the lower container. The annular groove of the lower container is filled with a liquid sealant, and the lower end of the upper container is inserted into the liquid sealant so that the liquid sealant can flow inside and outside the lower end of the upper container. Make sure to combine the upper and lower containers.

In the method for growing a single crystal of a compound semiconductor according to the present invention, the lower end of a closed container having a reservoir for volatile component raw material at the upper portion and having an opening at the lower portion is inserted into a crucible so that the crucible can be partially communicated. Is divided into the inner side and the outer side, the non-volatile component raw material and the liquid sealant are put in the crucible, the non-volatile component raw material and the liquid sealant are melted to form a melt, and the non-volatile component raw material is the liquid sealant in the outer region. It is covered with a non-volatile component in the inner region, and the volatile component raw material is heated and introduced as vapor into the internal space of the closed container to contact with the non-volatile component melt in the inner region of the crucible. The raw material and the non-volatile component raw material are combined to synthesize a compound melt,
The seed crystal attached to the lower end of the upper shaft is lowered while being rotated, soaked in the melt for seeding, and then the single crystal is pulled up after the seed crystal by pulling up the upper shaft.

The apparatus for growing a single crystal of a compound semiconductor according to the present invention comprises a crucible for holding a non-volatile component melt, a lower shaft for holding the crucible, a heater for heating a raw material inside the crucible, and a crucible. Of the raw material melt into an inner region and an outer region so as to communicate with each other only at the bottom of the container, and a closed container in which an upper container and a lower container are joined to form a closed state in the inner region, and an upper container and a lower container. A heater that heats the joint,
A reservoir for storing volatile components provided on the closed container, a heater for volatile component reservoir, an annular groove formed at the upper end of the lower container, a volatile component reservoir and an upper container. It has an upper shaft that is pierced through and can be rotated up and down, and the annular groove of the lower container is filled with a liquid sealant, and the lower end of the upper container is inserted into the liquid sealant, inside and outside the lower end of the upper container. The upper container and the lower container are connected so that the liquid sealant can flow therethrough.

In the continuous charge type single crystal growth method for a compound semiconductor of the present invention, the lower end of a closed container having a reservoir for volatile component raw material at the upper portion and an opening at the lower portion is inserted into a crucible, and a part thereof is inserted. The crucible is divided into the inside and the outside so that they can communicate with each other, the non-volatile component raw material and the liquid sealant are put in the crucible, the non-volatile component raw material and the liquid sealant are melted to form a melt, and the non-volatile component in the outer region. The raw material is covered with a liquid sealant so that the non-volatile components are exposed in the inner region, and the volatile component raw material is heated and introduced as vapor into the internal space of the closed container, and the non-volatile component melt in the inner region of the crucible is formed. Bring them into contact with each other to combine the volatile component raw material and the non-volatile component raw material to synthesize a compound melt, and descend while rotating the seed crystal attached to the lower end of the upper shaft to soak it in the melt for seeding. By pulling up Pulling the crystal followed by a single crystal, the non-volatile ingredient material is supplied from above the liquid sealant outer region of the crucible as a melt, pulling a single crystal continuously while replenishing nonvolatile component material.

The continuous charge type single crystal growth apparatus for a compound semiconductor according to the present invention comprises a crucible for holding a non-volatile component melt, a lower shaft for holding the crucible, and a heater for heating a raw material inside the crucible. -A closed container formed by combining an upper container and a lower container for dividing the raw material melt into an inner region and an outer region so that the inner region is sealed so that the raw material melt is communicated only with the bottom of the crucible; A heater for heating the joint between the container and the lower container, a reservoir provided on the closed container for storing volatile components, a heater for the volatile component reservoir, and formed on the upper end of the lower container Annular groove, an upper shaft rotatably and vertically pierced through the volatile component reservoir and the upper container, a non-volatile component raw material container provided outside the closed container, and a melt of the non-volatile component raw material container Of the liquid sealant in the outer area of the crucible in a closed container. A non-volatile component supply pipe dripping into the crucible leading to, the liquid sealing agent is filled in the annular groove of the lower container, the lower end of the upper container is inserted into the liquid sealing agent, The upper container and the lower container are connected so that the liquid sealant can flow inside and outside.
As a result, it is possible to automatically adjust so that there is almost no pressure difference between the inside and the outside.

In the case of the continuous charge of raw material, the supply pipe for the continuous non-volatile component may be divided into two. The first supply pipe is directly connected to the non-volatile component raw material reservoir, and the second supply pipe has an outlet above the liquid sealant in the outer region of the crucible. Since the outlet of the second supply pipe is not soaked in the melt, no reaction occurs in the pipe and the supply pipe is not clogged. The inlet of the second supply pipe may have a funnel-shaped inlet that widens upward. The raw material dropped from the outlet of the first supply pipe always enters the second supply pipe, and the non-volatile component raw material is surely introduced into the crucible.

In this case, quartz, carbon, carbon coated with PBN, carbon coated with SiC, carbon coated with AlN or the like can be used for the first supply pipe. These materials do not get wet with non-volatile components,
Since it does not chemically react with the non-volatile ingredients, it does not contaminate the ingredients. Also for the second supply pipe, any one of PBN, carbon coated with PBN, carbon coated with SiC or SiC, carbon coated with AlN or AlN 1
Seeds can be used. Since neither the first supply pipe nor the second supply pipe is wet with the non-volatile component, the pipes are not clogged due to the viscosity of the melt itself. Since it does not react chemically, the quality of raw materials is not impaired.

As the liquid sealant, B ₂ O ₃ or KC is used.
A eutectic of 1 and NaCl is used. These substances are glassy substances and soften when heated to cover the upper surface of the non-volatile component raw material. These raw materials can be protected and volatilization of volatile components can be prevented. Which is used as the liquid sealant depends on the volatile component. When As or P is a volatile component, B ₂ O ₃ is used as the liquid sealant.
That is, B ₂ O ₃ is used as a liquid sealant for growing GaAs, InP, GaP, InAs and the like. When Sb is used as a volatile component, a eutectic of KCl and NaCl is used as the liquid sealant. That is, this is used in the case of synthesis and growth of GaSb and InSb.

This is the case for liquid encapsulants that cover non-volatile components. The annular groove in the connecting portion of the upper container and the lower container and the liquid sealant for liquid sealing the upper shaft and the lower shaft do not depend on the non-volatile components as much as they cover the crucible. The liquid sealing agent for liquid sealing that does not come into contact with these melts is B ₂ O ₃ or Na.
Any eutectic of Cl and KCl may be used.

[0041]

According to the present invention, the closed container divides the melt in the crucible into the inner region and the outer region so as to partially communicate with each other. The surface of the outer region is covered with a liquid sealant. The inner region is exposed to the internal space of the closed container. The volatile component gas is introduced into the closed space, and is brought into contact with the non-volatile component melt through the exposed surface to cause a reaction. A melt of the compound is synthesized by the reaction. Since it is blocked by the closed container, the liquid sealant is trapped in the outer area and does not cover the surface of the inner area. The liquid sealant layer does not interfere with the above compounding reaction.

Further, two closed containers are used for the upper container and the lower container.
Divide and form an annular groove in the upper edge of the lower container. Put the liquid sealant in the annular groove. Insert the lower edge of the upper container into the liquid sealant and seal the liquid. A communication hole is formed near the lower end edge of the upper container, and a gap is formed between the lower end edge and the bottom of the annular groove so that the liquid sealant can flow. Even if a pressure difference occurs between the inner space and the outer space, the liquid sealant moves to allow the gas to flow, and works to cancel the pressure difference between the inside and the outside. Therefore, there is almost no pressure difference between inside and outside.
Then, the vertical movement of the liquid level of the melt inside and outside the crucible hardly occurs. Since there is no change in the melt surface, the reaction proceeds in a stable thermal environment.

This method can also be applied to a vapor pressure controlled crystal pulling technique. In this case, it is not necessary to cover the entire crucible with a closed container as in the above-mentioned conventional technique (conventional example; FIG. 5). This results in a smaller and simpler device. It can be carried out by only slightly modifying the production equipment of the liquid encapsulation pull-up method (LEC method), which is the mainstream in the production of compound semiconductors. Further, since the melt surface of the outer region Z of the crucible is covered with the liquid sealant, the melt can be prevented from being contaminated. One is that the liquid sealant blocks the arrival of impurities from the external space. The other is by positively absorbing impurities in the melt (gettering effect).

In the single crystal growth method for continuously supplying the raw material (continuous charge method), as in the prior art (FIG. 6), the tip end opening of the non-volatile component raw material supply pipe is a raw material melt containing a volatile component. It is plugged into the liquid. Alternatively, the non-volatile component raw material supply pipe is exposed to the atmosphere of volatile components. Therefore, there is a problem that the volatile component raw material reacts and solidifies with the non-volatile component raw material in the supply pipe, and the tip of the supply pipe is clogged. The present invention supplies the non-volatile ingredient material to the area covered by the liquid sealant outside the closed container. Therefore, no reaction occurs at the outlet of the supply pipe. In the present invention, the tip opening of the supply pipe has a structure in which it is held in an atmosphere in which volatile components are extremely small. Since the chemical reaction does not occur, there is almost no pipe clogging. Therefore, the raw material can be continuously supplied for a long time.

In order to further enhance this effect, the non-volatile component raw material supply pipe may be divided into two. The non-volatile component raw material is once discharged from the first supply pipe connected to the raw material reservoir into the open space. This is received at the funnel-shaped inlet of the second supply pipe. The second supply pipe passes the melt as it is and supplies it to the outer region Z of the crucible. The outlet of the second supply pipe is at a height apart from the melt. The partial pressure of the volatile component at the tip opening of the first supply pipe is negligibly small. for,
There is no possibility that GaAs will be deposited and clogged inside the first supply pipe.

The second supply pipe is made of a material which is less wetted by the non-volatile component raw material such as PBN. The non-volatile component raw material is entirely supplied to the crucible without adhering to the inside of the second supply pipe. Further, since the tip of the second supply pipe is held above the liquid sealant, there is no danger that the raw material melt enters the supply pipe and is solidified.

[0047]

【Example】

[Example (Synthesis of Polycrystal)] A first example of the present invention will be described with reference to FIG. This apparatus synthesizes GaAs polycrystals in a stainless steel closed container.
The outer wall of the furnace is not shown and only the internal structure is shown.

At the center of the lower part of the apparatus, a rotatable lower shaft 1 is vertically provided. A crucible 2 is supported on the upper end of the lower shaft 1. A raw material melt 3 of a non-volatile component (Ga melt) is housed in the crucible 2. The raw material melt 3 in the crucible 2 is separated into the inner side and the outer side by the lower end of the cylindrical closed container 4.
The two divided areas are distinguished as an inner area M and an outer area Z. The closed container 4 is divided into an upper container 40 and a lower container 41. There is a communication hole or a gap 42 at the lower end of the closed container 4 so that the raw material melt 3 can flow in and out.

The upper surface of the melt in the outer region Z of the raw material melt 3 is covered with the liquid sealant 5. Liquid sealant 5 is B
₂ O ₃ . This is to suppress the evaporation of As from the raw material melt. The upper surface of the inner region M of the raw material melt is not covered. The upper surface of the As gas needs to be exposed in order to react with the Ga raw material melt.

The closed container 4 includes an upper container 40 and a lower container 4.
It is a combination of 1. Special measures are made to the connecting portion 6 of both. An annular groove 44 composed of an annular outer wall 45, an inner wall 46 and a bottom wall 47 is formed on the cylindrical upper end of the lower container 41. The liquid sealant 48 is filled therein. The lower end 49 of the upper container 40 is also cylindrical and is immersed in the liquid sealant 48. Lower end 49 of upper container 40
Has a gap 50 between it and the bottom wall 47, and the volatile component (As gas) can flow in and out through this gap. Instead of the gap 50, a communication hole may be formed in the lower end 49. The inside of the closed container 4 is called an internal space S. The outside space inside the furnace (outer wall not shown) and outside the closed container 4 is referred to as W.

The internal space S is filled with a volatile component gas (As). The external space W is filled with a high pressure gas such as an inert gas (nitrogen, argon). The connecting portion 6 prevents the internal and external gases from being mixed with each other and prevents a large pressure difference between the inside and the outside. If there is a pressure difference between inside and outside,
Gas flows through the liquid sealant 48 to counteract the pressure differential. If the pressure difference between the inside and the outside is not canceled, the liquid surfaces in the inside and outside regions M and Z of the raw material melt 3 will be significantly imbalanced, and the thermal environment of the crystal during crystal growth will be disturbed. The liquid sealant 48 of the connecting portion 6 can prevent such a phenomenon.

It is not preferable that the gas flows from the external space W into the internal space S because impurities may be mixed. The gas may flow out from the inner space S to the outer space W. Therefore, it is desirable to maintain the pressure of the internal space S so as to be slightly higher than the pressure of the external space. Crucible 2
A first heater 9 having rotational symmetry is provided around the circumference of. This is a resistance heating heater that energizes a conductor such as a carbon to generate heat. The first heater 9 heats the raw material melt 3 and the liquid sealant 5 thereon.

Above the heater 9, there is a cylindrical second heater 10. This has the effect of heating the gas in the external space W, the internal space S, and the liquid sealant 48 above the crucible 2. As a result, the vapor pressure of As in the internal space S can be adjusted. Above the upper container 40 of the closed container 4, an As reservoir 8 containing a solid As7 is provided. Although this is a substantially closed space, it is connected to the upper container 40 by a communication pipe 51 slightly. The upper end 52 of the communication pipe 51 is open in the middle of the reservoir 8.
This is to prevent the As solid 7 from directly dropping into the raw material melt 3.

A heater 11 for heating the As reservoir 8 is installed around the As reservoir 8. The temperature of the As reservoir 8 is
It is monitored by thermocouple 12. By the As heating heater 11 and the thermocouple 12, the As vapor pressure inside the As reservoir 8 can be precisely controlled. A GaAs single crystal was synthesized by such a crystal synthesizer. Beginning upper container 4
0 has been pulled upwards. The lower end of the lower container 41 is inside the crucible 2.

The outer region Z of the PBN crucible 2 having a diameter of 185 mm was filled with 5.3 kg of solid high-purity (6N) Ga and 650 g of the liquid sealant B ₂ O ₃ . 6 kg of high-purity As solid was put into the As reservoir 8. An appropriate amount of the liquid sealant B ₂ O ₃ was also placed in the groove at the upper end of the lower container 41. The furnace was closed and the furnace was evacuated. Nitrogen gas N ₂ was introduced to adjust the nitrogen pressure in the furnace to 2 atm. The first heater 9 and the second heater 10 are energized to keep the temperature around the crucible 2 at 1240 ° C (G
The melting point of aAs was raised to 1238 ° C. Ga in the crucible 2 is melted and becomes a raw material melt. The liquid sealant also melts and covers the upper surface of the raw material melt 3 in the external region Z. The liquid sealant 48 in the annular groove 44 also melts.

After the temperature of the Ga melt in the crucible 2 is sufficiently stabilized, the upper container 40 is lowered and the lower end 49 is dipped in the liquid sealant 48 in the annular groove 44 of the lower container 41. As a result, the upper and lower containers 40 and 41 are combined to form the closed container 4. The As heating heater 11 was energized to heat the As reservoir 8. The temperature of the lowest temperature part in contact with the thermocouple 12 was set to 617 ° C. This is because the As pressure inside the As reservoir 8 is set to 1 atm. Since the partial pressure of As trapped in the container is equal to the vapor pressure of the lowest temperature part, the As partial pressure can be controlled by the lowest temperature.

While maintaining this state, a GaAs polycrystal was manufactured in the crucible. At the beginning, G is in crucible 2.
Although only a, As descends from above in a gas state, crosses the gas-liquid interface, dissolves in the melt, and combines into GaAs in the melt. Since the melting point of Ga is lower than 1238 ° C. (melting point of GaAs) and the melt temperature is kept at 1240 ° C.,
Even if it becomes aAs, it is in a molten state. That is, the melt in the crucible is a mixture of Ga melt and GaAs melt.
However, with time, the proportion of GaAs increases.

Since the internal space S and the external space W are shut off by the closed container 4, the internal space is not contaminated by impurities. The gas-liquid interface is exposed in the inner region M, but impurities are not mixed in the melt from here.
Further, since the outer region Z is covered with the liquid sealant 5, impurities are shielded by the liquid sealant and are not contaminated. Further progressing, the liquid sealant also has an effect of capturing impurities in the melt and improving the purity of the melt.

Even if a pressure difference occurs between the inner space S and the outer space W, the gas flows through the liquid sealant 48 in the joint portion 6 between the upper container 40 and the lower container 41, so that the pressure difference is canceled. Therefore, inside the crucible 2, the liquid level of the melt hardly rises and falls inside and outside. The liquid level is stable.
That is, the temperature distribution in the melt does not change. It is possible to synthesize stable compounds.

The pressure difference ΔP between the inside and the outside can be almost eliminated, but it does not become completely zero. The pressure difference is canceled by the gas flowing from the high pressure side to the low pressure side through the liquid sealant 48 of the connecting portion 6. At this time, the liquid level of the liquid sealant in one space is at the lower end 49 of the upper container 40, and the liquid level of the liquid sealant in the other space is lower than the upper edge of the lower container. The pressure difference ΔP at this time is obtained by multiplying the height difference ΔH of the liquid sealant at this time by the density ρ and the gravitational acceleration g.

ΔP = ρgΔH (1)

It is The value of ΔH when the gas flows depends on the amount of the liquid sealant initially filled in the annular groove 44. If the lower end 49 of the upper container 40 divides the annular groove 44 into two equal parts, the height when the heights of the liquid sealant inside and outside are equal is H, and the height from the bottom of the gap is F (H > F)

ΔH = 2H-2F (2)

It becomes The smaller the filling amount of the liquid sealant, the smaller (H → F) ΔH and the lower the upper limit of the pressure difference. On the other hand, the following equilibrium is established in the crucible. The height of the raw material melt from the bottom surface in the internal region M is X ₁ , and the pressure in the internal space is P ₁ . The height of the raw material melt in the outer region Z is X ₂ , and the thickness of the liquid sealant is D. If the pressure in the external space is P ₂ ,

P ₁ + ρ ₁ gX ₁ = P ₂ + ρ ₁ X ₂ g + ρDg (3)

It is The density ρ1 of the melt fluctuates as the reaction progresses, but this fluctuation occurs slowly. Also

| P ₁ −P ₂ | ≦ ΔP = ρgΔH (4)

Since the density ρ and the thickness D of the liquid sealant are invariant, the difference in height between the inside and outside of the raw material melt (X ₂ −X
It can be seen that ₁ ) hardly changes. Since the one shown in FIG. 4 does not have the constraint condition like (4), the fluctuation of the melt surface inside and outside is remarkable. In the present invention, As gas is supplied from the wide internal space S to the raw material melt through the wide gas-liquid interface. It does not add additional raw material to the melt in the crucible through a narrow feed tube, such as that shown in FIG. Therefore, the thin feed pipe is not clogged due to the formation of the compound.

Such a synthetic reaction is carried out by using As in the As reservoir 8.
I continued until 7 was gone. A melt of GaAs was obtained in the crucible. After cooling, the furnace was opened and the crucible was taken out. The solidified GaAs was taken out from the crucible and weighed. 11
kg of GaAs polycrystal was obtained. During temperature rise and synthesis,
The amount of As leaked to the outside through the joint portion of the closed container was about 5 mol%. It's just a small loss. 9 remaining
This means that 5 mol% was effectively used in the synthesis. In order to eliminate the pressure difference between the inside and the outside, the loss of As through the joint portion 6 is unavoidable to some extent. The loss of As is minimized.

[Example (Pulling of Single Crystal)] The example relates to a method for synthesizing a GaAs polycrystal. Next, an apparatus and method for pulling a GaAs single crystal will be described. The apparatus used is very similar to that shown in FIG. 1, but the mechanism necessary for pulling the single crystal is added. The structure of the single crystal pulling apparatus will be described with reference to FIG. Although there are some portions that overlap with FIG. 1, they will be described repeatedly without omission. The outer wall of the entire furnace is not shown here. A lower shaft 1 capable of rotating and ascending and descending is provided at the center of the lower side of the furnace. A bottomed cylindrical crucible 2 is mounted immediately above the lower shaft 1. Inside the crucible 2,
A Ga melt 3 which is a non-volatile component material is stored. A closed container 4 is hung from above the crucible 2.

The closed container 4 includes an upper container 40 and a lower container 41.
It is divided into two. The lower end of the lower container 41 is immersed in the melt 3. The raw material melt 3 is divided into the inside and outside by the lower end. The surface of the melt in the outer region Z has the liquid sealant 5 (B
₂ O ₃ ). The liquid surface of the inner region M is exposed. There is a gap 4 between the bottom of the lower container 41 and the bottom of the crucible.
There are two. The melt 3 can flow in and out through the gap 42. Instead of the gap, a communication hole may be formed in the wall surface of the lower container.

The upper container 40 and the lower container 41 are connected to each other by the connecting portion 6.
At, the seal is sealed by the annular groove 44 and the liquid sealant 48. This structure is similar to that of FIG. The annular groove 44 formed at the upper end of the lower container 41 includes an outer wall 45, an inner wall 46, and a bottom wall 47. There is an opening on the top. The liquid sealant 48 is placed here. Liquid sealant 48 and upper container 4
The lower end 49 of 0 is submerged. Due to the gap 50, the liquid sealant 48 can flow in and out. Instead of the gap, a communication hole may be formed near the lower end of the upper container 40. A cylindrical main heater 9 is provided outside the crucible 2 to heat the melt. Above that, there is a second heater 10 for heating the single crystal 16 to be pulled.

This embodiment also has an As reservoir 8 for containing the As solid 7. In this example, the upper container 40 of the closed container 4 and the As reservoir 8 are integrated. There is an upper shaft penetrating portion 13 at the center of the upper wall 54 of the As reservoir 8 and the upper shaft 1
4 is inserted downward. In order to seal the upper shaft 14, the upper shaft penetrating portion 13 is also specially devised. A dish-shaped portion 55 is formed in the center of the upper wall 54, and a through hole 56 is formed in the center thereof. A liquid sealant 57 is filled in the dish 55. Due to the liquid sealant, mixing of gas inside and outside through the hole of the upper shaft 14 can be prevented. Since only the liquid sealant is in contact with the upper shaft, the upward movement and rotation of the upper shaft are not hindered.

The bottom wall 59 of the As reservoir 8 also serves as the top wall of the upper container 41 of the closed container 4. Bottom wall 59
There is an opening 60 in the center of the, and a communication pipe 58 is provided upward from here. A heater 11 for As is provided so as to surround the As reservoir 8. When heated by the heater 11, As is vaporized and passes through the communication pipe 58, and steam is converted into a closed container 4.
Flows into the internal space S of. The upper shaft 14 is the upper shaft penetrating portion 13,
The internal space S of the closed container 4 passes through the communication pipe 58 and the opening 60.
Is plugged into. A seed crystal 15 is fixed to the lower end of the upper shaft 14. The seed crystal 15 is dipped in the raw material melt and seeded,
When the upper shaft 14 is rotated and pulled up, the single crystal 16 is pulled up.

This apparatus directly synthesizes a GaAs single crystal from a Ga raw material (nonvolatile component) and an As raw material (volatile component). Ga solids and a liquid sealant are placed in the outer region of the crucible 2. The As solid 7 is accommodated in the As reservoir portion 8, and the liquid sealant is also put in the upper shaft penetrating portion 13 and the upper and lower joint portions 6 of the closed container 4. A seed crystal 15 is fixed to the lower end of the upper shaft 14. After such preparation, the single crystal is pulled up. I will give an example.

A PBN crucible having a diameter of 185 mm is used.
In the outer region Z of the crucible, 5.3 kg of high-purity (6N) Ga solid and 650 g of B ₂ O ₃ are charged. 6 kg of a high-purity (7N) As solid is stored in the As reservoir 8. The furnace is closed and the heaters 9 and 10 are energized to use Ga as a melt.
The As solid is vaporized by the heater 11. As vapor enters the internal space S from the communication pipe 58, reacts with the melt, and G
It becomes an aAs melt. This is the synthesis of GaAs. After the synthesis is completed, the single crystal is pulled up.

The upper shaft 14 is rotated and lowered, and the seed crystal 15 is dipped in the raw material melt of GaAs for seeding. G by gradually pulling up the upper shaft while further rotating
Pull up the aAs single crystal. The vapor pressure of As in the internal space S is controlled by adjusting the temperature with the heater 10. Since this control is possible, the As solid is stored in the storage unit 8
Leave a little on. Crystal pulling was continuously performed, and finally a single crystal having a diameter of 4 inches and a length of 20 cm could be obtained.

In this method, due to the action of the heater 10,
As vapor pressure above the melt is controlled and pulling can be performed with a low temperature gradient. The dislocation density of the pulled single crystal was 3000 cm ^-2 or less. The crystal was a single crystal and the composition was stoichiometric. The electrical and physical properties were uniform throughout the crystal.

[Example (Continuous Charge Single Crystal Pulling)] The synthesis of GaAs polycrystal and the growth of GaAs single crystal (batch type) were described. Next, a continuous charge method for pulling a long single crystal by continuously supplying raw materials will be described. The method of FIG. 2 (Example) can only pull crystals corresponding to Ga initially contained in the crucible. The continuous charge method enables large crystal growth by successively supplying Ga.

This will be described with reference to FIG. This is a device in which a Ga continuous supply mechanism is added to the pulling device of FIG. Avoid repetition and only explain this part. A Ga raw material reservoir 18 is provided on the side of the closed container 4. This is a cylindrical closed container. Ga17 can be housed inside. At the lower bottom of the Ga raw material reservoir 18, there is a horizontally oriented first raw material supply pipe 19, through which a Ga melt can flow. A cylindrical heater 21 for Ga is provided around the Ga raw material reservoir 18. This has the function of heating the Ga solid to form a Ga melt. At the end of the raw material supply pipe 19, there is a dropping port 61, through which the Ga melt is dropped.

Immediately below it, a funnel 62 is opened. The funnel 62 is supported by the support plate 63.
Second raw material supply pipe 20 extending in the longitudinal direction following the funnel 62
There is. The lower end of this is open above the outer region Z of the crucible 2. Ga + GaAs melt in the outer region Z,
The Ga outlet 6 is provided in the upper space without coming into contact with the liquid sealant.
There are four. Since the supply tube is away from the melt, GaAs
There is no fear that the reaction that occurs will cause the supply pipe to be clogged. In this respect, it is possible to avoid the drawback of Japanese Patent Laid-Open No. 4-154689 shown in FIG.

This apparatus can load Ga raw material into both the crucible 2 and the Ga raw material reservoir 18. Ga can be added to the crucible during crystal growth. Therefore, a long crystal can be manufactured. Of course, it is necessary to store a sufficient amount of As in the As reservoir 8 in advance. An example is given. PB with a diameter of 185 mm
A crucible made of N was used. In the outer region Z of the crucible, 2 kg of high-purity (6N) Ga and 650 g of B ₂ O ₃ were put. 6 kg of high-purity (7N) As solid 7 in the upper As reservoir 8
Accommodated. High-purity Ga solid was also stored in the Ga raw material reservoir 18 and the lid was closed. A GaAs seed crystal 15 is attached to the lower end of the upper shaft 14.

In such a device, GaAs was first synthesized in the crucible as in the example. Ga in the crucible was heated by the heaters 9 and 10 to form a melt. As is heated by the heater 11 to be vaporized into vapor. This is introduced into the internal space S of the closed container 4 and combined with Ga through the exposed gas-liquid interface. G of melt in crucible
The a is gradually replaced by the GaAs melt. The synthesis of GaAs ends when all the Ga in the crucible becomes GaAs. At this time, a sufficient amount of As solid remains in the As reservoir 8. A sufficient amount of Ga melt remains in the Ga reservoir 18. The state at the end of the synthesis is like this.

Then, the pulling of the crystal is started. Upper shaft 14
To lower. Seed crystal G
The aAs melt is seeded and pulled up while rotating the upper shaft. Following the seed crystal, the single crystal is pulled up. As the single crystal is pulled up, the Ga reservoir 18 causes the Ga to enter the crucible.
Replenish the melt. It is desirable to prevent the liquid level of the GaAs melt from rising and falling by balancing the amount of replenishment with the amount of decrease by pulling.

In order to control the supply amount of Ga melt, for example, the following is performed. (1) A piston is provided in the Ga raw material reservoir 18. By pushing down the Ga melt by the piston, Ga
Is extruded from the dropping port 61 in an appropriate amount. (2) An inert gas (nitrogen, argon, etc.) is introduced into the Ga reservoir and pressure is applied to push out the Ga melt.

The Ga melt is supplied from the first raw material supply pipe 19 through the second raw material supply pipe 20 to the outer region of the crucible. The second supply pipe is made of PBN which is difficult to wet with the Ga melt. Therefore, Ga was not attached to the supply pipe and clogged. G along with crystal pulling
Give a to the crucible. This is the gap 42 (or communication hole)
And enters the inner area M. It combines with As vapor from above to form a GaAs melt. Since the GaAs melt is replenished one after another, the liquid level in the crucible is kept almost constant.

The raw material melt 3 is almost GaAs and contains a small amount of Ga. That is, crystal pulling can be performed while maintaining the same conditions. As reservoir 8, G
a The single crystal is pulled under the same conditions until the raw material in the reservoir 18 is exhausted. Thus, a diameter of 4 inches (about 10c
m), a GaAs crystal having a length of 20 cm was obtained. This confirmed that the entire length was a single crystal. In this case, too
The vapor pressure of As is controlled by the rotor 10, and the crystal can be pulled up with a low temperature gradient. The dislocation density of the obtained single crystal GaAs was 3000 cm ^-2 or less. It is a good single crystal with few defects.

Further, since Ga could be continuously supplied so that the melt of GaAs in the crucible was almost the same, a uniform resistivity characteristic was exhibited over the entire length of the crystal. It is a single crystal with excellent electrical properties.

[0089]

According to the present invention, a closed container having an open lower end is inserted into a non-volatile component melt in a crucible, the melt is divided into an inner part and an outer part, and an outer melt is covered with a liquid sealant. The closed container is divided into upper and lower halves, and the joint portion is sealed with a liquid sealant. Above the airtight container is a container for the volatile component raw material, from which the volatile component gas is supplied to the internal space of the airtight container. The melt in the internal region is combined with the volatile component gas to synthesize a melt of the 3-5 group compound.

Since the outside of the melt is covered with the liquid sealant, impurities are not mixed into the melt. The pressure difference between the inner space and the outer space is canceled by the gas flowing through the liquid sealant at the joint. Therefore, the heights of the liquid surfaces in the inner region and the outer region of the crucible hardly change. Therefore, the compound can be synthesized and the crystal can be grown in a stable thermal environment.

When the present invention is applied to the continuous charge type apparatus, the non-volatile component raw material is supplied to the outer region of the crucible. Since this is a space in which the partial pressure of volatile components is extremely low, the compound does not deposit in the supply pipe to cause clogging. Further, by forming the supply pipe with a material having low wettability with respect to Ga and In, it is possible to prevent clogging due to solidification of the nonvolatile component.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a compound semiconductor synthesizing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a batch type compound semiconductor single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a continuous charge type compound semiconductor single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a synthesizer of a Group 3-5 compound proposed by Japanese Patent Laid-Open No. 61-174105.

FIG. 5 is a cross-sectional view showing a crucible portion of a pulling device for a group 3-5 compound semiconductor proposed by JP-A-60-176995.

FIG. 6 is a schematic configuration diagram of a pulling device for a 3-5 group compound semiconductor proposed by Japanese Patent Laid-Open No. 4-154689.

[Explanation of symbols]

1 Lower Axis 2 Crucible 3 Raw Material Melt 4 Closed Container 5 Liquid Sealant 6 Bonding Part 7 As 8 As Raw Material Reservoir 9 First Heater 10 Second Heater 11 As Heater 12 Thermocouple 13 Top Shaft Penetration Part 14 Upper Axis 15 Seed Crystal 16 Single Crystal 17 Ga 18 Ga Raw Material Reservoir 19 First Raw Material Supply Pipe 20 Second Raw Material Supply Pipe 21 Ga Heater 22 Ga Volatile Component Raw Material 23 Double Columnar Tube 24 Nonvolatile Component Raw material melt 25 Liquid sealant (B ₂ O ₃ ) 26 Communication hole 27 Liquid sealant 28 Crucible 29 Closed container 30 As raw material reservoir 31 Ga raw material reservoir 32 As supply pipe 33 Ga supply pipe 40 Upper container 41 Lower container 42 Gap 44 Annular groove 45 Outer wall 46 Inner wall 47 Bottom wall 48 Liquid sealant 49 Lower end of upper container 50 Gap 51 Communication pipe 52 Upper end of communication pipe 54 Upper wall of volatile component raw material reservoir 5 Dish-shaped part 56 Through hole 57 Liquid sealant 58 Communication pipe 59 Bottom wall 60 Opening 61 Drop opening 62 Lot 63 Support plate 64 Ga outlet 70 Lower shaft 71 Crucible 72 Heater 73 Volatile component reservoir 74 Internal pipe 75 Outer Tube 76 Crucible 77 Partition Plate (Cylinder) 78 Raw Material Melt 79 Inner Area Melt Surface 80 Outer Area Melt Surface 81 Closed Container Lower Container 82 Closed Container Upper Container 83 Lower Shaft 84 Susceptor 85 Raw Material Melt 86 Floating Crucible 87 Communication hole 88 Vertical hole 89 Liquid sealant reservoir 90 Main heater 91 Auxiliary heater 92 Heater for liquid sealant 93 Group 3 heater 94 Group 5 heater 95 Upper shaft 96 Seed crystal 97 Single crystal 98 Upper shaft penetrating part 99 Dish-shaped container 100 Liquid sealant 101 Binding part 102 Outer wall 103 Bottom wall 104 Inner wall 105 Annular groove 106 Liquid sealant 107 For upper container End S inner space W external space M inner region Z outer region

Claims (11)

[Claims] 1. A crucible is provided at the lower end of a closed container which is composed of an upper container and a lower container which are connected to each other by a connecting portion sealed by a liquid sealant and which has a reservoir for a volatile component raw material above. Insert it inside, divide the crucible into the inner part and the outer part so that the melt can communicate at the bottom, put the non-volatile component raw material and liquid sealant on the outside of the crucible, melt the non-volatile component raw material and liquid sealant, and melt. As a liquid, the non-volatile component raw material is covered with a liquid sealant in the outer region, and the non-volatile component is exposed in the inner region, and the volatile component raw material is heated and led to the internal space of the closed container as vapor, A method for synthesizing a compound semiconductor, which comprises contacting a non-volatile component melt in an inner region to combine a volatile component raw material and a non-volatile component raw material to synthesize a compound melt. 2. B ₂ O ₃ or KCl and NaC as a liquid sealant on the raw material melt in the joint part of the closed container and in the crucible.
The method for synthesizing a compound semiconductor according to claim 1, wherein a eutectic of 1 is used. 3. A crucible is provided at the lower end of a closed container which is composed of an upper container and a lower container which have a reservoir for a volatile component raw material and which are connected by a joint sealed by a liquid sealant. Insert it inside, divide the crucible into the inner part and the outer part so that the melt can communicate at the bottom, put the non-volatile component raw material and liquid sealant on the outside of the crucible, melt the non-volatile component raw material and liquid sealant, and melt. As a liquid, the non-volatile component raw material is covered with a liquid sealant in the outer region, and the non-volatile component is exposed in the inner region, and the volatile component raw material is heated and led to the internal space of the closed container as vapor, Contact the non-volatile component melt in the inner region, combine the volatile component raw material and the non-volatile component raw material, synthesize the compound melt, and lower the melt while rotating the seed crystal attached to the lower end of the upper shaft. Soaked in seeds A method for growing a single crystal of a compound semiconductor, which comprises pulling an upper axis and pulling a single crystal subsequently to a seed crystal. 4. A crucible is provided at the lower end of a closed container which is composed of an upper container and a lower container which have a reservoir for the raw material of a volatile component above and which are joined by a joint sealed by a liquid sealant. Insert it inside, divide the crucible into the inner part and the outer part so that they can communicate with each other, put the non-volatile component raw material and the liquid sealant on the outer side of the crucible, melt the non-volatile component raw material and the liquid sealant to form a melt. , The non-volatile component raw material is covered by the liquid sealant in the outer region, and the non-volatile component is exposed in the inner region, and the volatile component raw material is heated and led to the internal space of the closed container as vapor, and the inner region of the crucible Contact the non-volatile component melt to combine the volatile component raw material and the non-volatile component raw material to synthesize the compound melt, lower the seed crystal attached to the lower end of the upper shaft while rotating it, and soak it in the melt. Seeds, The single crystal is pulled up after the seed crystal by pulling up the upper axis, and the non-volatile component raw material is supplied as melt from above the liquid sealant in the outer region of the crucible, and both the non-volatile component raw material and the volatile component raw material are supplied. A method for growing a single crystal of a compound semiconductor, which comprises pulling a single crystal continuously while replenishing. 5. B ₂ O ₃ or KCl and NaC as a liquid sealant on the raw material melt in the joint part of the closed container and in the crucible.
5. The method for growing a single crystal of a compound semiconductor according to claim 3, wherein a eutectic crystal of 1 is used. 6. A crucible for holding a non-volatile component melt,
The lower shaft holding the crucible, the heater for heating the raw material inside the crucible, and the raw material melt are divided into the inner region and the outer region so that they are connected only at the bottom of the crucible, and the inner region is sealed. A closed container formed by connecting an upper container and a lower container to each other, a heater for heating a joint portion between the upper container and the lower container, and a volatile component for accommodating a volatile component provided on the closed container. Component reservoir, heater for volatile component reservoir,
An annular groove formed at the upper end of the lower container, the annular groove at the upper edge of the lower container is filled with a liquid sealant, the lower end of the upper container is inserted into the liquid sealant, and the upper container An apparatus for synthesizing a compound semiconductor, characterized in that an upper container and a lower container are combined so that a liquid sealant can flow in and out of a lower end. 7. A crucible for holding a non-volatile component melt,
The lower shaft holding the crucible, the heater for heating the raw material inside the crucible, and the raw material melt are divided into the inner region and the outer region so that they are connected only at the bottom of the crucible, and the inner region is sealed. A closed container formed by connecting an upper container and a lower container to each other, a heater for heating a joint portion between the upper container and the lower container, and a volatile component for accommodating a volatile component provided on the closed container. Component reservoir, heater for volatile component reservoir,
An annular groove formed in the upper end of the lower container, a volatile component reservoir, and an upper shaft that can be rotated up and down through the upper container are provided, and the annular groove at the upper edge of the lower container is filled with a liquid sealant. The lower end of the upper container is inserted into the liquid sealant, and the upper container and the lower container are combined so that the liquid sealant can flow in and out of the lower end of the upper container. For growing single crystal of compound semiconductor. 8. A crucible for holding a non-volatile component melt,
The lower shaft holding the crucible, the heater for heating the raw material inside the crucible, and the raw material melt are divided into the inner region and the outer region so that they are connected only at the bottom of the crucible, and the inner region is sealed. A closed container formed by connecting an upper container and a lower container to each other, a heater for heating a joint portion between the upper container and the lower container, and a volatile component for accommodating a volatile component provided on the closed container. Component reservoir, heater for volatile component reservoir,
An annular groove formed at the upper end of the lower container, an upper shaft rotatably moved up and down through the volatile component reservoir and the upper container, a non-volatile component raw material container provided outside the closed container, and a non-volatile Equipped with a non-volatile component supply pipe that guides the melt of the ingredient material container above the outer region of the crucible in the closed container and drops it into the crucible that drops the open space, and liquid seals in the annular groove at the upper edge of the lower container Filled with an agent, insert the lower end of the upper container into the liquid sealant, and combine the upper container and the lower container so that the liquid sealant can flow in and out of the lower end of the upper container. An apparatus for growing a single crystal of a compound semiconductor, comprising: 9. A supply pipe for supplying a non-volatile component raw material from a non-volatile component raw material container to a crucible is divided into two supply pipes, a first supply pipe and a second supply pipe, and the first supply pipe is non-volatile. It is directly connected to the component container, the second supply pipe has a funnel at the upper part and the lower end is opened above the crucible, and the non-volatile component raw material is the first supply pipe connected to the non-volatile component raw material container. From the above, it was dropped into the funnel of the second supply pipe, passed through the second supply pipe, dropped in the open space, passed through the liquid sealant in the outer region of the crucible, and reached the melt. The single crystal growth apparatus for compound semiconductors according to claim 8. 10. Quartz, carbon, carbon coated with PBN, Si as a material of the first supply pipe for feeding the non-volatile component raw material from the non-volatile component raw material container to the second supply pipe.
10. A compound semiconductor single crystal growth apparatus according to claim 9, wherein either carbon coated with C or carbon coated with AlN is used. 11. A material for the second supply pipe for guiding the non-volatile component raw material fed from the first supply pipe onto the crucible is PB.
Carbon, SiC or Si coated with N or PBN
10. Use of carbon coated with C, AlN, or carbon coated with AlN.
A single crystal growth apparatus for a compound semiconductor according to 1.